Sound Practices Mailing List Files - Volume 1
=========================================================================
From: "Bottlehead" <Bottlehead@prodigy.net>
Subject: B-52s and Lowthers (long)
Date: Wed, 26 Nov 1997 09:06:24 -0800
Source: Sound Digest Archive v01.n120
>
> I had a pretty fair weekend myself. Took my 6SL7/46/VV52 amps over to a
> friend's house and hooked them up to a pair of ProAc Response 3s (!),
with
> a little help from his dedicated subwoofers. They didn't do badly at
all.
> Maxed out on Prokofiev, but of course I'm still only running the 52s at
80
> ma to accomodate the FS030s. Gotta get me some of Mikey's big fellas!
:-)
>
Yeah, Grover, burn them suckers, at least 450V 120 mA, more is probably
better. They should give you gobs of bottom end, like no other tube. I
thought that maybe the 52s could be run the same way as the 32s when I got
them (say 350V 70 mA), but they want to burn. They work wonders on my PM2As
on the bottom.
Mike says the RS-520 should be a killer OT, having been designed for the
52s, but I'm so hung up on parafeed that I haven't tried the combo yet.
Speaking of the Lowthers, some minor miracles took place this week.
Firstly I'd like to thank Mr. Uchida of Sun Audio for finally breaking them
PM2As in during VSAC. Secondly, here's my current recipe for PM2As in
Medallion cabs-
a) loan your drivers to someone else for 6 months. This will help you avoid
any (additional ) brain damage during the painful breakin period. The most
important thing about Lowthers is not to listen to them until they are
broken in. This may take up to a year. If you slip up and listen to them
during this period, don't blame me if you decide to sell them.
b) listen to the method, but not the madness, of other Lowther owners. By
this I mean, try general approaches, but ignore the exact details of how
much damping, where it goes, etc. This held me back for a year. My dear
friend Tony G. is as guilty of this as anyone. Ignore the phrase "It works
in my room."
c) through much diddling, here is my recipe. *Only consider this as a
starting point for your own situation, and remember that breakin is the
most important step*
Line the driver chamber back wall. Try either a Deflex pad or 1/4 to 3/8"
felt. I am using felt right now because I gave away the Deflex panels Jon
Ver Halen sent me, in a fit of compassion for another Lowther owner.
Line the bottom and rear angled baffle of the Medallion mouth with felt
too. This kills some standing wave biz, I think I measured 70, 140, 280 Hz
at some point in the past. Now, take 12, not 1, not "three, gently teased
out", not 1/2" weatherstrip foam, but 12 small cotton balls, and stuff that
goddamn gap between the whizzer and the main cone, so that the balls are
about 1/3 exposed. Don't tell me I'm killing the midrange, you bet I am,
with extreme prejudice. It needs the shit beat out of it, twice. Not only
does this cotton stuff the "horn" between the whizzer and cone that makes
the 2 khz peak, it damps the edge of the whizzer, which rings like a bell.
To do this right maybe you need to string the balls on thread, like Xmas
popcorn, but I just put the grill back on and the cloth does a fair job of
holding the balls in place, unless you pull out them drum CDs and run at
6-8 watts (my ears were ringing for a full day after that stupidity). As
far as I'm concerned, no clarity is lost in this operation. If you are a
long time Lowther owner you will possibly disagree that this gives flatter
midrange response, but I submit that your brain is fooling you. I get
tenacious headaches whenever I listen to Lowthers that are not damped in
some way.
After all this I ran a test record sweep, and I'll be damned if it didn't
sound very respectably flat from say 12 Khz to 100 Hz, with a minor peak
somewhere around 8 kHz. I was frankly amazed.
By the way that parafeed 45 amp shines with the Lowthers, but I am using
the 52 amp, while I revel in Way Too Loud for a while.
d) Many Lowther owners will say I am lying, no Lowther starts to roll of at
100Hz. And besides all that bass in other speakers is fake.
Are you people feeling OK? Go the the symphony once in a while! Listen to a
real tympani, tuba, double bass.
Yes a Lowther makes a little noise at 50 Hz, but who cares? It is many dB
down from the rest of the curve. Let's get real here folks.
d)Subwoofer.
Ok, so I have the Whamo bandpass box. Not quite as efficient, maybe 2-3 db
down, but good for 35 -100 Hz, no crossover.
So I put a pair of 25W 211 amps on the 96 dB subs, and about 10W of VV52 on
each Medallion.
Hey not perfect, the 211 amps are a bit mushy in the bass, and I'm not real
big on the out of phase back wave from the horn, a wee bit slow and hollow,
and yes the sub is wired out of phase to match. But this is pretty effing
good. Vocals are quite realistic on the 2As for the first time, the classic
Lowther mid and treble clarity is retained without the deadly peaks.
Saxophone is marvelous.
The presentation is good enough that this system will spell the Hyperwhamos
for a while, being cleaner in the mid and top, although not as clean in the
midbass and a bit less extended on top. It has also inspired some soon to
be done eXperimentation with PM2As and a not ready yet to be revealed
woofer combo, in new cabinets.
Let me finish here by saying that 35 wpc on this system (96-99 dB) is
almost enough....
Doc B., saying "Huh?"
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: Re: B-52s and Lowthers (long)
Date: Wed, 26 Nov 1997 21:38:11 -0600
Source: Sound Digest Archive v01.n120
At 9:06 AM -0800 11/26/97, Bottlehead wrote:
>>
>> I had a pretty fair weekend myself. Took my 6SL7/46/VV52 amps over to a
>> friend's house and hooked them up to a pair of ProAc Response 3s (!),
>with
>> a little help from his dedicated subwoofers. They didn't do badly at
>all.
>> Maxed out on Prokofiev, but of course I'm still only running the 52s at
>80
>> ma to accomodate the FS030s. Gotta get me some of Mikey's big fellas!
>:-)
>>
>Yeah, Grover, burn them suckers, at least 450V 120 mA, more is probably
>better. They should give you gobs of bottom end, like no other tube. I
>thought that maybe the 52s could be run the same way as the 32s when I got
>them (say 350V 70 mA), but they want to burn. They work wonders on my PM2As
>on the bottom.
>Mike says the RS-520 should be a killer OT, having been designed for the
>52s, but I'm so hung up on parafeed that I haven't tried the combo yet.
Well, yeah! Get him to loosen up, fer chrissakes, and send me a pair for
free, huh? :-) Or get him to do a nice plate choke at 150ma/20H. Heck, at
600 Rp that's all the inductance I need, eh? Then I can keep my 030s!
Don't you love being talked about in the third person, Mike?! :-)
Seriously, I can't *wait* to get these guys up to speed, but even at 80ma
they are still sounding awfully good.
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: "Henry Pasternack" <hap@nortel.ca>
Subject: Baby Ongaku criticism.
Date: 21 Jan 1998 15:12 EST
Source: Sound Digest Archive v01.n167
A couple of people have written to me in private email and it seems
that my coments on Reichert's "It's not my amp" philosophy have been
mixed up with my feelings about the Wavelength Audio 2A3 amp. Let me
set the two issues straight.
With regard to the amplifiers I built, obviously they are not "Baby
Ongakus" in the strictest sense because I made some changes in parts
selection, power supply topology and layout. I'm aware that this kind
of amplifier is sensitive to all of these things and it's not my intent
to criticize Rankin, Garber, or Reps on the basis of the results I have
had with my own project. I was simply reporting for the interest of the
group's readers how I went about building my amps and how they sounded
to me in one particular listening test.
I realize that Reichert had nothing to do with the "Baby Ongaku"
design. I wished to address his remarks in the "Flesh and Blood"
article. Let me express myself a different way. These circuits
being so simple, it seems to me that people like Herb Reichert are
calling themselves designers and innovators on the basis of their
experiments with parts selection in implementations of classic
circuits. I find this to be overly prideful and disrespectful to
the truly brilliant and original engineers who actually dreamt up
and realized the technology decades ago.
As well, I would like to see some consistency if I am to take
these people as reliable sources of practical information. It is
no great thing to be changing one's mind all of time time. I do
not see the flavor-of-the-month phenomenon as evolution as much
as aimless wandering. For the past five years, I have tried to
put together a cohesive picture of how all of these tweaks fit
together, and I'm still largely in the dark. The bottom line:
I took Reichert's comments to mean, "You can build it your way,
but you'd be a fool not to do it my way." I didn't like that,
and felt he could have phrased himself differently. After all,
experimentation is part of the fun.
Finally, I can't seem to avoid controversy whenever I subscribe
to this list. I guess it's because I bottle up a lot of frustration
with all the silly bickering that goes on in audiophile circles.
And I have no discipline. Well, I'm not going to gang up on
anyone this time.
Meanwhile, what I really wanted was comments and criticisms on
the Nardi preamp circuit. Surely someone read the article...?
- -Henry
=========================================================================
From: dslagle@earthlink.net
Subject: Re: Baby Ongaku criticism.
Date: Wed, 21 Jan 1998 18:16:28 -0800 (PST)
Source: Sound Digest Archive v01.n167
>Henry opined as follows:
>
>>These circuits being so simple, it seems to me that people like Herb
>>Reichert >are calling themselves designers and innovators on the basis of
>>their
>>experiments with parts selection in implementations of classic
>>circuits. I find this to be overly prideful and disrespectful to
>>the truly brilliant and original engineers who actually dreamt up
>>and realized the technology decades ago.
>
I see it a bit diffrently.... are there any new circuits out there?? are
there any truly brilliant engineers out there designing completely original
tube circuits???
Take any brilliant amp out there, and break it apart, and i bet somewhere
someone has already done it.... i guess thats the rub working with 70 year
old technology.
I see a lot of people taking 3-4 old ideas and glueing them together to
make their new one.... but what is new??? and where the hell does one come
up with the idea that newer is better, or something needs to be engineered
to be better... better is better thats it.
there are a large # of people here who gladly take their old technology
since to us is sounds better than 99.9% of the wonderful engineering out
there today..
as for the whole voodoo thing, I see it a bit differently....
take an amp with a low part count such as the reichert flesh and blood it
is actually conceivable to go through part by part make swaps and learn,
and come up with opinions on what a particular part sounds like in that
circuit, so even if you don't like it the way herb designed it, you are
allowed to disagree...
get even simpler to the potato amp... it can be built with 10 parts,
including the PS... any swap you can hear... I guess its a poorly designed
circuit????
granted, certain parts will show a bigger difference than other when
swapped, but what are we taking about here??? take output transformers....
will a well designed circut make all outputs sound the same??? how about
the more complex the circuit?? In the case of the potato, it was the first
time i heard the difference between CC and metal film resistors (100 ohm
grid stopper) now the same swap (MF for CC) in the same position of a ST-70
(1K before the EL-34's) showed me no difference... so i guess the ST-70 is
a better design??? Geee could it be that the more parts there are, the
less each individual part matters?
herb is no engineer, rather an artist.... art can be anything... it makes
it oh sooo simple... engineers can argue anything to death and win on
paper... its their job.... an artist has one job... get a response ... it
can be good bad or indifferent, but it is based on emotion and nothing
else... how do you measure emotion??? I don't much care to measure
anything... engineering will show us functionality... and is great to tell
us if something will work, but beyond that???
I love voodoo... its something someone who barely knows ohms law can use
against the big bad engineers... herb gives all of us poor wannabees the
faith that it doesn't take a genius to build a good amp... he lays the
foundation with what he did... and tells us exactly how to do it... then
like a good mother... pushes us out of the nest and forces us to fly....
when given the option of the intimidating audio engineer who hawks his
product with tons of specs, or the voodoo artist, i'll take voodoo... it
gives me hope and lets me believe in my own opinions... the engineer gives
me reasons to look up the recommended components list.
i'm sure someday there will be a p-spice for audio with *voodoo* parts
selection, and what will that tell us??? nothing more than herb did in his
flesh & blood article... this is what I like!
dave
=========================================================================
From: tubesguy@mail.execpc.com (Patrick Currie)
Subject: Re: Baby Ongaku criticism.
Date: Wed, 21 Jan 1998 19:56:52 -0500
Source: Sound Digest Archive v01.n167
Henry opined as follows:
>These circuits being so simple, it seems to me that people like Herb
>Reichert >are calling themselves designers and innovators on the basis of
>their
>experiments with parts selection in implementations of classic
>circuits. I find this to be overly prideful and disrespectful to
>the truly brilliant and original engineers who actually dreamt up
>and realized the technology decades ago.
Well, yow. I don't know that Herb called himself either a designer or an
innovator. My read on the article, and, admittedly, I read at only the
32nd grade level, is that he presented an amplifier that he was fairly
happy with, and told everyone exactly how to build it to exactly duplicate
its sound. Just a guess, but a cascaded 6SN7 into a 300B, as simple as the
notion is, probably wasn't dreamt up and realized decades ago, or, if it
was, it was never made known to the world. SE triode amps for high-end
audio is, as Herb himself has pointed out, a relatively recent phenomenon,
and owes less to brilliant and original engineers than it does to
fun-loving experimenters, mostly from Japan.
> Finally, I can't seem to avoid controversy whenever I subscribe
>to this list. I guess it's because I bottle up a lot of frustration
>with all the silly bickering that goes on in audiophile circles.
Hmm, hasn't been much bickering here until the last few days. Of course,
this is anything but an "audiophile circle." :-) - Pat
Pat Currie (tubesguy@execpc.com)
=========================================================================
From: "Henry Pasternack" <hap@nortel.ca>
Subject: re:Re: Baby Ongaku criticism.
Date: 22 Jan 1998 12:53 EST
Source: Sound Digest Archive v01.n168
Pat Currie writes:
>Well, yow. I don't know that Herb called himself either a designer or an
>innovator. My read on the article, and, admittedly, I read at only the
>32nd grade level, is that he presented an amplifier that he was fairly
>happy with, and told everyone exactly how to build it to exactly duplicate
>its sound. Just a guess, but a cascaded 6SN7 into a 300B, as simple as the
>notion is, probably wasn't dreamt up and realized decades ago, or, if it
>was, it was never made known to the world. SE triode amps for high-end
>audio is, as Herb himself has pointed out, a relatively recent phenomenon,
>and owes less to brilliant and original engineers than it does to
>fun-loving experimenters, mostly from Japan.
Hmmm. Well, Herb Reichert has written a lot more than just that
one article. His letter to the Editor of "Stereophile" attacking
Scott Frankland was a good summary of his position, and revealing
of Herb's many misconceptions about the history of amplifier design
and his place in that history. It was also silly. As for RC coupled
single-ended hi-fi amplifiers, they certainly have been around for
decades, and well-known to the world. Finally, as clever as our
friends in Japan are, true brilliance was what it took to develop
the thermionic valve in the first place, and figure out the circuits
that are the basis of all contemporary tube amplifiers. That happened
long before many of us were born.
As someone wrote to me this morning in personal email, you don't
take a dyna amp, change out the resistors and capacitors, and claim
it's your design and not Hafler's. This isn't art. It's skilled
craftsmanship. I happen to agree twith Michael LaFevre that there
is great honor in being a craftsman. You just have to understand
that there is a difference between a master artist and a proficient
student. I understand that art students learn their craft by
copying the works of the masters. I imagine they also become
adept at varying the elements in order to render individualized
impressions of pre-existing works. But what is artistic genius?
I suppose it's coming up with a whole new way of expressing
subjective perception. I'm sorry, this is not what Herb Reichert
is doing.
Anyway, I do apologize for all this criticism. In terms of
keeping the technology and craft alive, and finding ways to
improve classic circuits with modern components, the work all
of you folks are doing is invaluable as well as great fun to
read about.
- -Henry
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: Baby Ongaku criticism.
Date: Fri, 23 Jan 98 08:32:23 -0500
Source: Sound Digest Archive v01.n168
Henry,
I am sorry to hear that your out was not consistent with the others who
have built and enjoyed the Baby-O, MQ2A3, Trumpet design. Even reviews
that appeared in Absolute Sound.
I classify any amplifier into thirds as design, part quality and
construction. Lets assume that your build quality was ok, this is only
one third the design for which was published.
If you read the Bugle article I am not too found of the 2A3, finding the
45 much better sonically matched to acceptable speakers. First though
lower wattage amplifiers require a choke loaded power supply because they
need the self regulation properties to function into complex loads in the
lower frequencies.
Three clairifactions on the circuit publised:
1) Don layout does not include the the resistor divider that puts the
filament voltage for the 12AT7 at the right point.
2) The power supply inductor that I have used for this design is a 15H
hammond unit at 75ma.
3) For the capacitor after the choke in the power supply I use a
100uF*2/500V Cerafine in parallel with a 20uF SCR across it making a
total effective cap of 220uF after the choke.
Henry, why not try it this way before you give up on it.
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: William Eckle <wmeckle@uswest.net>
Subject: Bach's speakers ?
Date: Thu, 29 Oct 1998 11:10:41 -0700
Source: Sound Digest Archive v01.n473
At 08:09 PM 10/28/98 GMT, David Barnett wrote:
>
>>What kind of monitors do you think Bach had in his own studio?
>
>I think she used Altecs. Oh, wait, that's Wendy Carlos, nee
>Walter....
Little known sidebar:
Bach used to spend most all his time composing in his second story
room. His wife
repeatedly called him downstairs for his meals. He ignored her calls and
continued composing.
His wife, worried about his health, because of his missing so many
meals, fixed a hot
meal and took it up to his composing room.
This practice has survived to this day, only we call it:
|
|
|
Hot Bach's lunch !
=========================================================================
From: Eric Weitzman <eweitzman@acm.org>
Subject: RE: Bach's speakers ?
Date: Thu, 29 Oct 1998 12:32:11 -0800
Source: Sound Digest Archive v01.n473
This may not be true, but someone once told me that the
first Brandenburg Concerto was written with bach-loaded
horns in mind.
- - Eric
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: Bach's speakers ?
Date: Fri, 30 Oct 1998 02:37:45 -0800
Source: Sound Digest Archive v01.n473
Eric Weitzman wrote:
> This may not be true, but someone once told me that the
> first Brandenburg Concerto was written with bach-loaded
> horns in mind.
>
> - Eric
That would be the Second Brandenburg Concerto, but very funny none the
less!
dbk
=========================================================================
From: Joe Pledger <doodle@navicom.com>
Subject: Back!
Date: Mon, 10 Nov 1997 21:42:01 -0800
Source: Sound Digest Archive v01.n104
Hi Gang,
Just couldn't stand it! Waved my towel in the air, and flagged a passing
Vorlon Cruiser. Really missed being on the list!
Joe pledger
=========================================================================
From: davidbarnett@aristotle.net (David N. Barnett)
Subject: Re: Back!
Date: Tue, 11 Nov 1997 07:37:33 GMT
Source: Sound Digest Archive v01.n104
On Mon, 10 Nov 1997 21:42:01 -0800, Joe Pledger <doodle@navicom.com>
wrote:
>Just couldn't stand it! Waved my towel in the air, and flagged a passing
>Vorlon Cruiser. Really missed being on the list!
Don't you mean "Vogon?" If so, I hope you weren't subjected to any of
their poetry.
- --dnb
=========================================================================
From: STEVE CORNETT <SCORNETT@usagroup.com>
Subject: Re: Back!
Date: Tue, 11 Nov 1997 08:16:27 -0600
Source: Sound Digest Archive v01.n105
Joe Pledger wrote:
"Just couldn't stand it! Waved my towel in the air, and flagged a passing
Vorlon Cruiser. Really missed being on the list!"
To which dnb replied:
"Don't you mean "Vogon?" If so, I hope you weren't subjected to any of
their poetry."
Yes, I'm afraid Joe mixed his (Sci-Fi) metaphors. The Vorlons are part of
the Babylon 5 Universe.
Steve (Deep Thought) C.
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: Re: Back!
Date: Tue, 11 Nov 1997 08:33:30 -0600
Source: Sound Digest Archive v01.n105
At 9:42 PM -0800 11/10/97, Joe Pledger wrote:
>Hi Gang,
>
>Just couldn't stand it! Waved my towel in the air, and flagged a passing
>Vorlon Cruiser. Really missed being on the list!
>
>Joe pledger
Yeah!
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: Marc Elmlund <marc@wineasy.se>
Subject: Re: Back!
Date: Tue, 11 Nov 1997 09:58:46 +0100
Source: Sound Digest Archive v01.n105
At 21.42 -0800 97-11-10, Joe Pledger wrote:
>Hi Gang,
>
>Just couldn't stand it! Waved my towel in the air, and flagged a passing
>Vorlon Cruiser. Really missed being on the list!
WB. I hope they didn't make you listen to any poetry.
Regards
Marc Elmlund
Stockholm, Sweden
aka marc@wineasy.se
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: Back!
Date: Wed, 12 Nov 1997 10:16:52 +0100 (MET)
Source: Sound Digest Archive v01.n106
At 21:42 10/11/1997 -0800, Joe pledger wrote:
>Just couldn't stand it! Waved my towel in the air, and flagged a passing
>Vorlon Cruiser. Really missed being on the list!
That's a good thing!
Going out of the list you nearly made the mean age of the list members
became less than 40!
Best regards,
Jean-Michel Le Cleac'h
=========================================================================
From: Johari Yip <hfyip@pacific.net.sg>
Subject: Re: Back!
Date: Thu, 13 Nov 1997 07:12:52 +0800
Source: Sound Digest Archive v01.n106
Le Cleac'h J.-M. wrote:
>
> At 21:42 10/11/1997 -0800, Joe pledger wrote:
>
> >Just couldn't stand it! Waved my towel in the air, and flagged a passing
> >Vorlon Cruiser. Really missed being on the list!
>
> That's a good thing!
>
> Going out of the list you nearly made the mean age of the list members
> became less than 40!
>
> Best regards,
>
> Jean-Michel Le Cleac'h
Hi everyone,
Due to my overseas attachment, I'll have to unsubscribe from the joelist
for the moment. Can someone show me what I should do?
Thanks in advance and see you soon!
Regards,
Johari
=========================================================================
From: pitaro@ozemail.com.au
Subject: Re: Back!
Date: Thu, 13 Nov 1997 15:02:30 EST
Source: Sound Digest Archive v01.n107
** Reply to note from davidbarnett@aristotle.net (David N. Barnett) Tue, 11 Nov 1997 07:37:33 GMT
>
> On Mon, 10 Nov 1997 21:42:01 -0800, Joe Pledger <doodle@navicom.com>
> wrote:
>
> >Just couldn't stand it! Waved my towel in the air, and flagged a passing
> >Vorlon Cruiser. Really missed being on the list!
>
> Don't you mean "Vogon?" If so, I hope you weren't subjected to any of
> their poetry.
>
I don't know what all the fuss is about.
Vogon poetry is quite pleasing! :)
Regards,
Harry Pitaro
+-----------------------+---------------------------------------------+
| Melbourne, Australia | A good discussion is like a miniskirt; |
| | Short enough to retain interest |
| pitaro@ozemail.com.au | and long enough to cover the subject. |
+-----------------------+---------------------------------------------+
=========================================================================
From: "Lohse, Guenther VIM37" <Lohse.Guenther@dornier.dasa.de>
Subject: back horn chamber
Date: Thu, 18 Sep 97 08:29:00 PDT
Source: Sound Digest Archive v01.n029
hey all,
hey bert, robert, dave
there are some discussions on back chambers of backloaded horns I've heard
(between above list members). Because I am recently offline I could not
follow the discussion. Please can anyone mail me the discussion details.
g}nther
lohse.guenther@dornier.dasa.de
=========================================================================
From: Edgar Faulkner <efaulkne@wsunix.wsu.edu>
Subject: back horns
Date: Wed, 17 Sep 1997 15:05:25 -0700 (PDT)
Source: Sound Digest Archive v01.n028
All the interest in this type of enclosure has me wanting to start
another project, just for fun.
I have two pair of Audax HM130ZO drivers and would be interested in trying
them in this type of enclosure. How do I determin the parameters of such a
box? These drivers are not currently in use and I am willing to try almost
anything to get some 2way system they might work in.
Any refrences for additional information will be appreciated. Even if the
idea doesn't hold water please explain why.
______________________________
Ed Faulkner \ through a child's eyes
Instructional Support Services \ sky is blue
Washington State University \ grass is green
Pullman, WA 99164 \ I want to see again
(509) 335-7566 \
efaulkne@wsu.edu. \_________________________________
=========================================================================
From: tubesguy@execpc.com (Patrick Currie)
Subject: Back horns - New Lowther prices
Date: Wed, 17 Sep 1997 20:19:15 -0500
Source: Sound Digest Archive v01.n028
Please pardon the blatantly commercial content, but there is new Lowther
Club pricing intended to encourage folks to deal with the Club rather than
anyone in, say, Missouri. The new prices are:
PM6C - $420/pr (all prices are per pair, not including shipping)
7C - 490
2C - 640
PM6A - 649
7A - 1090
2A - 1150
5A - 1500
4A - 1800
DX2 - 650
3 - 725
The Lowther Club of America is also apparently going to some type of
internet/web site/some guy in northern California/based sales system, so if
you or anyone else is interested in Lowthers, please contact Tom Ronan or
me while we're still involved, which I suspect will not be long. You may
be able to save a buck, or even a couple. - Pat
Pat Currie, Lowther Club of America Upper Midwest Representative
(608)233-8956, 266-9290 (Madison, WI)
=========================================================================
From: darmah@goodnet.com
Subject: Re: backhorns PAUL AND GORDON ARE RIGHT!!!
Date: Sat, 28 Mar 1998 09:47:50 +0000
Source: Sound Digest Archive v01.n234
Hi Paul and Gordon:
Congrats on the following conclusion. I've been preaching what you
said below for a long time with regards to horn design.
> What I mean is that so many of these designs are full of $%#@. The
> longer the better, yea right then you have this midbass drop out.
I agree 100% with you. That's why I always call the Mau horn the
"Mau-PIPE" myself. And I don't mean this as a crtisism.
> Anyhow, I conclude that back-loading can be made to work well if you
> know what you are doing. I don't think that I do;
WRONG!!!!!!!!!!!!! If you've realized this then you're much closer to
knowing what you're doing than most others. You will have also have
realized (I think) that small horns are a lot more like pipes than is
generally excepted.
< I did some simulations of the Acousta a while back that suggested
<it should have good strong bass, louder than the mids, down to 40Hz
<or so - but that sure ain't what I hear!
And it isn't what most other people hear either.
I'm seriously thinking of getting myself into big trouble by adding a
"mini horn primer" to my web page.
But then I'll probably have to got into hiding.
Best Redards
Marc S. Wauters
darmah@goodnet.com
Internet Paging: "http://wwp.mirabilis.com/544722"
My Home Page: "http://www.goodnet.com/~darmah/"
=========================================================================
From: Yip Hin Fai Johari <hfyip@pacific.net.sg>
Subject: Re: backhorns PAUL AND GORDON ARE RIGHT!!!
Date: Sun, 29 Mar 1998 11:28:29 +0800
Source: Sound Digest Archive v01.n235
>< I did some simulations of the Acousta a while back that suggested
><it should have good strong bass, louder than the mids, down to 40Hz
><or so - but that sure ain't what I hear!
>
>And it isn't what most other people hear either.
I agree that the Acousta, to certain extent, outperforms the Mauhorn in the
Mid
but you can't deny the fact that it(Acousta) doesn't go down low enough to
really give you satisfying sound. So naturally, going for a longer horn to
go down lower
in the frequencies is the best way but it brings along with it a new sets
of problem.
Johari
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: backhorns PAUL AND GORDON ARE RIGHT!!!
Date: Mon, 30 Mar 98 11:08:47 -0500
Source: Sound Digest Archive v01.n237
Johari
As far as I know the Acousta was not really a design of Lowther and that
it has serious problems in itself.
My point is that not enough thought is going into these designs except
for the though of ultimate bass output. Instead someone should realize
that the throat has much to do with the amout of output needed and at
what freq you need it at.
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "P.A. & M. Almeflo" <sd@ljusdal.se>
Subject: backhorns (was: Why we use permaalloy)
Date: Thu, 26 Mar 1998 22:28:30 +0100
Source: Sound Digest Archive v01.n231
Gordon wrote:
> I would say that I think those that are designing the backhorns need to
> go back to school. Robert Lamarre is on the right track.
What track is that, is he leaving back loaded horns?
Best regards,
Per Arne Almeflo
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: backhorns (was: Why we use permaalloy)
Date: Fri, 27 Mar 1998 16:52:56 -0800
Source: Sound Digest Archive v01.n233
J. Gordon Rankin wrote:
>
> >What track is that, is he leaving back loaded horns?
>
> What I mean is that so many of these designs are full of $%#@. The longer
> the better, yea right then you have this midbass drop out.
Probably should have chimed in here earlier. I had the chance last
year to visit Kevin Scott of Living Voice in Nottingham (UK). He makes
the Air Partner and Air Scout speakers (was recommended to me by Simon
Shilton by email). I heard the Air Scout (his 16 cubic foot
minimonitor!) and it was a mind-blowing experience, easily the best
I'd heard. He uses a back-horn on a 12" driver, but the horn is fairly
short and does not try to go lower than 60Hz or so. Acoustic crossover
to direct radiation must have been around 200 Hz or so; the midrange
kicks in at 500 - so very narrow bandwidths in the bass. (There was a
dual-12 front-horn-loaded subwoofer also in the system).
Anyhow, I conclude that back-loading can be made to work well if you
know what you are doing. I don't think that I do; I did some
simulations of the Acousta a while back that suggested it should have
good strong bass, louder than the mids, down to 40Hz or so - but that
sure ain't what I hear!
- -Paul Joppa
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: backhorns (was: Why we use permaalloy)
Date: Fri, 27 Mar 98 16:56:47 -0500
Source: Sound Digest Archive v01.n233
>What track is that, is he leaving back loaded horns?
What I mean is that so many of these designs are full of $%#@. The longer
the better, yea right then you have this midbass drop out.
I have a customer who built the BelCante Lowther design, from plans
supplied by Lowther with a PM5A. First thing I asked if he noticed the
drop out (See this is a 3M horn). The same is true with the Mauhorn.
Listen here is some simple info for back horn loading:
1) Determine the -3dB point of the driver in free space or better yet
loaded in a enclosure with a throat close to what you need.
2) Design a horn that the top freq is -3dB at the same point as 1
3) Live with the lowend not going down as far as you would like.
What has happened is that these so called designers are trying to reach
20Hz with a Lowther, well good luck! Reps yea maybe, Lowther no way. So
live with a 50Hz system and forget going any lower.
FYI, the customer above bought a pair of Reps1 put them in his BelCante
and well, WOW came to mind.
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "P.A. & M. Almeflo" <sd@ljusdal.se>
Subject: RE: backhorns (was: Why we use permaalloy)
Date: Sun, 29 Mar 1998 19:23:04 +0200
Source: Sound Digest Archive v01.n235
J. Gordon Rankin wrote:
> 1) Determine the -3dB point of the driver in free space or better yet
> loaded in a enclosure with a throat close to what you need.
>2) Design a horn that the top freq is -3dB at the same point as 1
What is top freq? Do you mean lowpass cutoff or highpass cutoff?
>Lowther no way. So live with a 50Hz system and forget going
>any lower.
Do you say that a Lowther has its -3dB point at 50Hz in free space?
Best regards,
Per Arne Almeflo
=========================================================================
From: "P.A. & M. Almeflo" <sd@ljusdal.se>
Subject: RE: backhorns (was: Why we use permaalloy)
Date: Sun, 29 Mar 1998 19:23:04 +0200
Source: Sound Digest Archive v01.n238
J. Gordon Rankin wrote:
> 1) Determine the -3dB point of the driver in free space or better yet
> loaded in a enclosure with a throat close to what you need.
>2) Design a horn that the top freq is -3dB at the same point as 1
What is top freq? Do you mean lowpass cutoff or highpass cutoff?
>Lowther no way. So live with a 50Hz system and forget going
>any lower.
Do you say that a Lowther has its -3dB point at 50Hz in free space?
Best regards,
Per Arne Almeflo
=========================================================================
From: Thomas Eberhard <Thomas.Eberhard@labmed.ki.se>
Subject: Re: backhorns (was: Why we use permaalloy)
Date: Tue, 31 Mar 1998 06:53:51 +0100
Source: Sound Digest Archive v01.n238
>Anyhow, I conclude that back-loading can be made to work well if you
>know what you are doing. I don't think that I do; I did some
>simulations of the Acousta a while back that suggested it should have
>good strong bass, louder than the mids, down to 40Hz or so - but that
>sure ain't what I hear!
>
>-Paul Joppa
sure ain't what I measure either.
Measured in center of horn opening using a Philips 9710 as a driver.
Hz dB (rellative at 200 Hz)
400 -18
315 -6
250 0
200 0
160 +2
125 0
100 -2
80 -10
63 -16
50 -18
Thomas H Eberhard
Clinical Microbiology VOX 08-5177 49 72
Karolinska Institute FAX 08-5177 58 50
S 171 76 Stockholm E-M Thomas.Eberhard@labmed.ki.se
"The higher we soar the smaller we appear to
those who cannot fly." Friedrich Wilhelm Nietzsche
=========================================================================
From: "P.A. & M. Almeflo" <sd@ljusdal.se>
Subject: RE: backhorns (was: Why we use permaalloy)
Date: Tue, 31 Mar 1998 19:13:25 +0200
Source: Sound Digest Archive v01.n239
J. Gordon Rankin wrote:
> FYI my Spike Fostex 168 Sigma horn info in response relative to 90Hz,
> Tractix 40Hz
>
> Freq Horn Combined
> 200 -8db 0
> 150 -6db 0
> 100 -3dB 2
> 90 0 1
> 80 1dB -1
> 70 2dB -2
> 50 6dB 0
> 40 9dB -2
> 30 2dB -5
> 20 -7dB -12
That looks really great; +/-2dB combined from 40-200Hz.
How did you measure the combined SPL?
Is the horn designed for 1/1, 1/2, 1/4 or 1/8 space?
What is the size of the horn mouth?
Do you feel you would gain from a subwoofer?
Are you satisfied with this driver and horn design?
With kindest regards,
Per Arne Almeflo
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: RE: backhorns (was: Why we use permaalloy)
Date: Tue, 31 Mar 98 10:32:06 -0500
Source: Sound Digest Archive v01.n239
Per Arne Almeflo,
>What is top freq? Do you mean lowpass cutoff or highpass cutoff?
Sorry for the use of non technical terms, the top frequency or highpass
cutoff. But even more than that anyone who has made a Backhorn realizes
that they will keep going because information into the horn such as
higher bidbass and even midrange info is passed.
>>Lowther no way. So live with a 50Hz system and forget going
>>any lower.
>
>Do you say that a Lowther has its -3dB point at 50Hz in free space?
No that 50Hz is about the best you are going to do from the back horn.
FYI my Spike Fostex 168 Sigma horn info in response relative to 90Hz,
Tractix 40Hz
Freq Horn Combined
200 -8db 0
150 -6db 0
100 -3dB 2
90 0 1
80 1dB -1
70 2dB -2
50 6dB 0
40 9dB -2
30 2dB -5
20 -7dB -12
This only took about 2 solid months to get it that good, the second one
took 3 days.
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: Thomas Eberhard <Thomas.Eberhard@labmed.ki.se>
Subject: Re: backhorns (was: Why we use permaalloy) part2
Date: Wed, 1 Apr 1998 07:09:46 +0100
Source: Sound Digest Archive v01.n240
>What did you use to measure with? I feel that I have good bass but now you
>got me wondering. But I have two Lowthers in one common backhorn and I would
>think that would make a big difference. Move your speakers side by side
>and put >them in the corner of your room you may like what you hear.If you
>toe them out >a little you will retain some if not most of your imaging.
I used a Technics Audio Frequency Analyser SH-8000. It is a sine wave
generator 20-20 000 Hz in 1/3 octave intervals with 8 Hz warble on top and
it have a microphone and a dB meter as well.
I later found out that the Philips was a bad choise of driver as it had a
Qt close to 1. I breifly tried a pair of Hokutone 8" drivers and they gave
better bass but I wanted to keep the fullrange concept. My conclusion is
that the Accousta size horn really is to small to work as a horn below 80
Hz and that the pipe like behaviour dominates below this frequency. An
option would be to have a big bass chamber giving a 12 dB cutof above 50 Hz
but then the advantage of high radiation resistance of a horn is lost. (If
we simplify the horn to a 12dB/ oct fall below 100 Hz and a 12dB/oct above
200 Hz the introduction of the bass chamber gives a system flat betwen
50-100 Hz with a 12 dB/oct fall below that and and a 12 db/oct above 100 hz
that increase to 24dB/oct above 200 Hz, this feature is present in some of
the Accousta variants).
Thomas
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: backhorns (was: Why we use permaalloy) part2
Date: Thu, 2 Apr 98 11:27:20 -0500
Source: Sound Digest Archive v01.n242
>I later found out that the Philips was a bad choise of driver as it had a
>Qt close to 1. I breifly tried a pair of Hokutone 8" drivers and they gave
>better bass but I wanted to keep the fullrange concept. My conclusion is
>that the Accousta size horn really is to small to work as a horn below 80
>Hz and that the pipe like behaviour dominates below this frequency. An
>option would be to have a big bass chamber giving a 12 dB cutof above 50 Hz
>but then the advantage of high radiation resistance of a horn is lost. (If
>we simplify the horn to a 12dB/ oct fall below 100 Hz and a 12dB/oct above
>200 Hz the introduction of the bass chamber gives a system flat betwen
>50-100 Hz with a 12 dB/oct fall below that and and a 12 db/oct above 100 hz
>that increase to 24dB/oct above 200 Hz, this feature is present in some of
>the Accousta variants).
Tom,
What is with the small mouth Lowther enclosures, are they just cutting
the horn off at say 30%? The mouth on my horn was 36" high...
I believe that more driver->horn reseach is needed in this area. You just
can't stick any old driver in a backhorn and expect it to work (unless
you are looking just to get sound out the other end). I believe that the
A and C drivers of Lowther fame should not be used in the same horns as
well as 6&7 should not be used in the same designs as 2&5's.
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: Robert Peterson <rpeterso@arthur.avalon.net>
Subject: backhorn tips wanted
Date: Wed, 7 Oct 1998 20:16:03 -0500 (CDT)
Source: Sound Digest Archive v01.n445
I'm just finishing up my back loaded horns and thought I'd seek out some
tips on how to treat the back chamber. Mainly I'm concerned about mid
colorations from sound reflecting back into the driver. Some materials I
am considering are Deflex panels and modeling clay which seems like a very
dead and easy to use material. Any other notions... or should I leave it
clean?
Thanks,
Robert
=========================================================================
From: Robert Lamarre <rlamarre@rlacoustique.com>
Subject: Re: backhorn tips wanted
Date: Wed, 7 Oct 1998 23:25:25 -0400
Source: Sound Digest Archive v01.n445
At 08:16 PM 10/7/98 -0500, you wrote:
>I'm just finishing up my back loaded horns and thought I'd seek out some
>tips on how to treat the back chamber. Mainly I'm concerned about mid
>colorations from sound reflecting back into the driver. Some materials I
>am considering are Deflex panels and modeling clay which seems like a very
>dead and easy to use material. Any other notions... or should I leave it
>clean?
>Thanks,
>Robert
>
>
Hi Robert,
I have tried many back chamber treatment materials.
In all fairness, it depends on so many variables that your best bet is to try
Deflex, wool, clay, etc.... and choose the method YOU prefer the most.
Cheers,
========== Robert Lamarre ===========
RL Acoustique, Creator of The Lamhorn
rlamarre@rlacoustique.com------------
www.rlacoustique.com-----------------
ph./fax: 450-653-3461 Canada---------
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: backhorn tips wanted
Date: Thu, 08 Oct 1998 20:21:37 -0700
Source: Sound Digest Archive v01.n447
Robert Peterson wrote:
>
> I'm just finishing up my back loaded horns and thought I'd seek out some
> tips on how to treat the back chamber. Mainly I'm concerned about mid
> colorations from sound reflecting back into the driver. ...snip...
Check out Speaker Builder last month - there are some actual
measurements of sound-absorbent materials at close to normal
incidence. This assumes of course that you really want to reduce
reflections, and not to tune them to a pleasing characteristic
instead. Which is often done while pretending that it's eliminating
reflections.
To significantly reduce the reflection at the first front-back
resonance frequency needs a near-optimum material whose thickness is
1/2 the cavity depth. Sonex foam for example (with the wedge-shaped
surface like in anechoic chambers) exists in 2", 3", and 4" depths,
suitable for 4", 6", and 8" cavities. Be warned though - this is not
"politically-correct" material, it's only scientific. Many audiophiles
will likely tell you to use something else that is technically a worse
absorber. And I'm not being entirely cynical here - it has often
happened that a scientifically-correct approach is not the best
sounding one, and the pseudo-scientific explanation may be bogus but
the sound is not!
hth,
- -Paul Joppa
=========================================================================
From: "Ken Dangerfield" <bpyakd@mail.island.net>
Subject: Backloaded horns
Date: Fri, 26 Sep 1997 15:11:58 -0800
Source: Sound Digest Archive v01.n045
For front loaded horns, one of the important factors in determining
low end cut off is the area of the mouth.
However, in many of the currently popular back loaded horns (e.g.
Medallion and the Lowther bicors) the mouth only flares vertically in
the last leg, whereas the horizontal dimension is maintained at the
same (relatively narrow) width for the full height of the enclosure.
If the last leg of the horn, starting from the last bend and
continuing to the mouth, employed the tractrix expansion in both the
horizontal and vertical planes (without increasing the height of the
mouth), one could increase the area of the mouth substantially,
thereby potentially improving the low end cut off, while at the same
time preserving the narrow baffle above the mouth to minimize
difraction of mids and highs.
I recognize that there are many other factors at work in determining
the overall performance of a back loaded horn. This just seems like
a relatively easy modification to an existing design which wouldn't
interfere with any of the other dimensions or parameters but might
aid the low end.
If someone has experimented with this or can point out the fallacy of
my question, I would be most interested in your comments. TIA
Regards,
Ken Dangerfield
=========================================================================
From: Thomas.Eberhard@labmed.ki.se (Thomas Eberhard)
Subject: RE:Backloaded horns
Date: Mon, 29 Sep 1997 19:44:37 +0200
Source: Sound Digest Archive v01.n048
>For front loaded horns, one of the important factors in determining
>low end cut off is the area of the mouth.
snip
>If the last leg of the horn, starting from the last bend and
>continuing to the mouth, employed the tractrix expansion in both the
>horizontal and vertical planes (without increasing the height of the
>mouth), one could increase the area of the mouth substantially,
>thereby potentially improving the low end cut off, while at the same
>time preserving the narrow baffle above the mouth to minimize
>difraction of mids and highs.
snip
>Regards,
>Ken Dangerfield
In the German journal Klang & Ton 5/96 they have the construction "Cheap
Trick 164" were they have a backloadad horn for the Fostex FE 103 Sigma.
They have a very narrow front, 15 cm but the horn opening flares to twise
that with.
They get a good response, measured in the horn mouth, down to 65-70 Hz.
With the back chamber undamped they got a uneven peaky response from the
horn and the waterfall plot showed some nasty ridges in the 1-8 kHz range.
Filling the chamber with cotton eliminated the peaks and ridges but also
attenuated the bass horn by 5 dB. Covering the walls with BoFoam eliminated
the ridges in the waterfall diagrams and reduced the peakyness with minimal
attenuation of the bass horn. They used a foldning with the horn moth
backwards so by having the opening close to the backwall it can be further
extended.
Thomas H Eberhard
Klinisk Mikrobiologi VOX 08-5177 49 72
Karolinska Sjukhuset FAX 08-5177 58 50
S 171 76 Stockholm E-M thomas@labmed.ki.se
The great tragedy of Science - the slaying of a beautiful hypothesis
by an ugly fact. - Thomas Henry Huxley
=========================================================================
From: Bastien Bouchard <bastien.bouchard@sympatico.ca>
Subject: Re: Backloaded horns
Date: Tue, 30 Sep 1997 09:56:26 -0400
Source: Sound Digest Archive v01.n049
Thomas Eberhard wrote:
Covering the walls with BoFoam eliminated
> the ridges in the waterfall diagrams and reduced the peakyness with minimal
> attenuation of the bass horn.
Thomas,
What is Bofoam? I can't figure exactly.
Bastien
=========================================================================
From: "Mark Donen" <soledadd@worldnet.att.net>
Subject: Back loaded horns
Date: Wed, 7 Jan 1998 12:12:30 -0500
Source: Sound Digest Archive v01.n155
Anyone have plans for backloaded horns. I have seen photos of two JBL cabs
that look good. C55 & C43. They are for double and single 15" respectively.
Does anyone know em?
TIA
Mark
=========================================================================
From: "Ken Dangerfield" <bpyakd@mail.island.net>
Subject: Backloaded horns and Reactance Annulling
Date: Tue, 30 Sep 1997 11:42:06 -0800
Source: Sound Digest Archive v01.n049
In his "Showhorn" article in Speaker Builder 2/90, Dr. Edgar observes
that throat reactance (which rises as the flare frequency is
approached) will choke off the low end response of a horn before the
flare frequency is reached. However, this throat reactance can be
"annulled" by use of a sealed back chamber of appropriate volume. He
then presents formulae for calculating the theoretical optimum throat
size and back chamber volume for a given driver/horn combination.
In a typical backloaded horn, what is considered to be the throat?
Also, the back chamber (if there is one at all) is not sealed and is
simply a direct extension of the horn itself. In some designs (some
Lowthers for example) the driver fires back directly into the
uppermost part of the horn and there is no additional volume behind
the driver which could be regarded as a "back chamber".
So with this in mind:
1. By what means is reactance annulling accomplished in a
backloaded horn ?
2. Are there formulae adapted to calculating for backloaded horns
the values which are analagous to throat size and back chamber volume
in a frontloaded horn so that the appropriate amount of "annulling"
can be accomplished? If so, where can I find them?
TIA
Regards,
Ken Dangerfield
=========================================================================
From: Michel Paquette <paqm01@GEL.USherb.CA>
Subject: Re: Backloaded horns and Reactance Annulling
Date: Tue, 30 Sep 1997 18:29:20 -0400
Source: Sound Digest Archive v01.n050
Hello Ken,
I can look in Beranek's book on Acoustics here at the library. I doubt
that you would be able to do some reactance annulling with a horn on both
sides of the driver. In fact, I wonder if the having two horns worsens
the problem by have the same reactance problem on both sides of the driver
(supposing similart types of horns on the front and the rear). OTOH, it
could be that since that the horns are driven out of phase it does act like
reactance annulling but I doubt that also. You can always phone Dr Edgar.
I did once and he was very nice person to talk to.
best regards,
Michel
>In his "Showhorn" article in Speaker Builder 2/90, Dr. Edgar observes
>that throat reactance (which rises as the flare frequency is
>approached) will choke off the low end response of a horn before the
>flare frequency is reached. However, this throat reactance can be
>"annulled" by use of a sealed back chamber of appropriate volume. He
>then presents formulae for calculating the theoretical optimum throat
>size and back chamber volume for a given driver/horn combination.
>
>In a typical backloaded horn, what is considered to be the throat?
>Also, the back chamber (if there is one at all) is not sealed and is
>simply a direct extension of the horn itself. In some designs (some
>Lowthers for example) the driver fires back directly into the
>uppermost part of the horn and there is no additional volume behind
>the driver which could be regarded as a "back chamber".
>
>So with this in mind:
>
>1. By what means is reactance annulling accomplished in a
>backloaded horn ?
>
>2. Are there formulae adapted to calculating for backloaded horns
>the values which are analagous to throat size and back chamber volume
>in a frontloaded horn so that the appropriate amount of "annulling"
>can be accomplished? If so, where can I find them?
>
>TIA
>Regards,
>Ken Dangerfield
=========================================================================
From: cjg2@concentric.net
Subject: Backloaded horns, full-range driver ???s
Date: Tue, 27 Oct 1998 22:37:40 -0500
Source: Sound Digest Archive v01.n471
Could anyone point me to some references on design+construction of rear
loaded horns? I have read several SP and 'net articles on enclosures
designed specifically for Lowthers, but I'd like to build something a la
Diatones and some other fullranges I've got around (Altec 755Es and Stephens
FR80s). I assume the horn calculations are the same for backloaded as for
frontloaded, but am guessing there are some special design considerations
(like the recently mentioned compression chamber size, etc.) Anything from
Speaker Builder, AES journals, or other?
The practicality (read--simplicity in design and sound!) of fullrangers is
just what the doctor ordered for me...limited space and finances.
Admittedly, I'd love to have horns from 20hz on up, but that will have to
wait. In the meantime, midrange magic, absence of HF nastiness, and
reasonable LF to 50hz is just fine.
BTW, anybody know anything about 755Es, like what makes them different from
Cs (the magnet is definitely not alnico)? I haven't had them in cabinets
yet, but they make nice sound from about 45hz to 17kHz (amazed I can hear
that high) on the oscillator.
Best wishes--Chris
=========================================================================
From: Martin Needleman <mrndlmn@bayserve.net>
Subject: Re: Backloaded horns, full-range driver ???s
Date: Tue, 27 Oct 1998 23:04:15 -0500 (EST)
Source: Sound Digest Archive v01.n471
Hey Chris,
Your 80FRs and 755s will drop into an unaltered Lowther backhorn cabinet
without a fuss. Try it and be prepared for magic.
Say Goodnight Gracie.
mrn
On Tue, 27 Oct 1998 cjg2@concentric.net wrote:
> Could anyone point me to some references on design+construction of rear
> loaded horns? I have read several SP and 'net articles on enclosures
> designed specifically for Lowthers, but I'd like to build something a la
> Diatones and some other fullranges I've got around (Altec 755Es and Stephens
> FR80s). I assume the horn calculations are the same for backloaded as for
> frontloaded, but am guessing there are some special design considerations
> (like the recently mentioned compression chamber size, etc.) Anything from
> Speaker Builder, AES journals, or other?
>
> The practicality (read--simplicity in design and sound!) of fullrangers is
> just what the doctor ordered for me...limited space and finances.
> Admittedly, I'd love to have horns from 20hz on up, but that will have to
> wait. In the meantime, midrange magic, absence of HF nastiness, and
> reasonable LF to 50hz is just fine.
>
> BTW, anybody know anything about 755Es, like what makes them different from
> Cs (the magnet is definitely not alnico)? I haven't had them in cabinets
> yet, but they make nice sound from about 45hz to 17kHz (amazed I can hear
> that high) on the oscillator.
>
> Best wishes--Chris
>
=========================================================================
From: Martin Needleman <mrndlmn@bayserve.net>
Subject: Re: Backloaded horns, full-range driver ???s
Date: Wed, 28 Oct 1998 18:47:38 -0500 (EST)
Source: Sound Digest Archive v01.n472
Hey Gordon,
Speaking from current experience, dropping the 755A into a backhorn is
anything but a waste of time. Fitting them into a Lowther Acousta 115
cabinet absolutely transformed my 1957 Altec 755A's (thanks Robert
Root!). I hated these things in the recommended 2 cubic foot box. Liked
them much better in a largish open baffle but the backhorn finally allows
me to understand that the reputation of these silly little puppies is
justified - glorious quick mids and a lower register that drops to 70Hz
tunefully with impact and authority. Voices so real that, at times,
guests have looked around trying to find the speaker/singer. Treble is
more than adequate for my faltering 65 year old ears.
We're not talking theory here. We're not talking T/S parameters. We're
talking music. We're talking cleaning the wax out of our ears and
listening.
On Wed, 28 Oct 1998, J. Gordon Rankin wrote:
> Chris,
>
> Pick your drivers well, both the 755 and Diatone are not good picks for
> backhorns. The 755 was made for sealed and the P610MB for ported. Using
> them in a backhorn would be a waste of time.
<================ snip =====================>
>
> Have fun, hope you have a lot of patients.
>
> Gordon
Golly, gosh Mr. Peabody. I didn't know Chris was a doctor.
mrn
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: Backloaded horns, full-range driver ???s
Date: Wed, 28 Oct 1998 21:51:42 -0800
Source: Sound Digest Archive v01.n472
J. Gordon Rankin wrote:
> ...snip...
> As far as info use the expansion type that you are interested in
> (Tractix, Expontial). Treat the horn as though you were designing a
> straight horn, do not consider this a bass horn with a sealed back area.
> Determine the lowend cutoff and throat size and length. Most people agree
> the length should be more than 50% of the needed length. Also horns with
> very long lengths (over 2M) tend to be very poor preformers. Also
> cornering at less than 120 degrees is a must, stay away from the horns
> that have 180 degree bends as the response is very irratic.
...snip...
Great post, Gordon - thanks!
One other point - backhorns usually have a small back chamber between
the driver and the horn proper. This volume acts as a lowpass filter
so the horn only operates at low frequencies, usually below 200 Hz or
less. Sort of an acoustic subwoofer crossover. All the usual articles
on horn design mention this (as a front chamber of course!). With
low-mass cones, the acoustic resonances of this small box are audible
through the cone, so it is somewhat important at higher frequencies
also.
- -Paul Joppa
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: Backloaded horns, full-range driver ???s
Date: Wed, 28 Oct 98 11:10:54 -0500
Source: Sound Digest Archive v01.n472
>Could anyone point me to some references on design+construction of rear
>loaded horns? I have read several SP and 'net articles on enclosures
>designed specifically for Lowthers, but I'd like to build something a la
>Diatones and some other fullranges I've got around (Altec 755Es and Stephens
>FR80s). I assume the horn calculations are the same for backloaded as for
>frontloaded, but am guessing there are some special design considerations
>(like the recently mentioned compression chamber size, etc.) Anything from
>Speaker Builder, AES journals, or other?
Chris,
Pick your drivers well, both the 755 and Diatone are not good picks for
backhorns. The 755 was made for sealed and the P610MB for ported. Using
them in a backhorn would be a waste of time.
The drivers that work (or require) the back horn have low Qt and high Fs.
For these the only way to get bass is by backloading (amplifing) that
little bit available at lower frequencies. Fostex, Lowther, Reps etc...
~~~~~~~~~~
As far as info use the expansion type that you are interested in
(Tractix, Expontial). Treat the horn as though you were designing a
straight horn, do not consider this a bass horn with a sealed back area.
Determine the lowend cutoff and throat size and length. Most people agree
the length should be more than 50% of the needed length. Also horns with
very long lengths (over 2M) tend to be very poor preformers. Also
cornering at less than 120 degrees is a must, stay away from the horns
that have 180 degree bends as the response is very irratic.
Have fun, hope you have a lot of patients.
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: Backloaded horns, full-range driver ???s
Date: Thu, 29 Oct 98 11:26:05 -0500
Source: Sound Digest Archive v01.n473
Paul, Martin etc...
>One other point - backhorns usually have a small back chamber between
>the driver and the horn proper. This volume acts as a lowpass filter
>so the horn only operates at low frequencies, usually below 200 Hz or
>less. Sort of an acoustic subwoofer crossover. All the usual articles
>on horn design mention this (as a front chamber of course!). With
>low-mass cones, the acoustic resonances of this small box are audible
>through the cone, so it is somewhat important at higher frequencies
>also.
There is some calculations on this volume and the upper point in the
response of the horn, but I have found that even more monkeying around is
required to make sure the higher freq. do not come through the horn.
Martin, I was not claiming that 755's would not sound good in backhorns,
maybe not needed. You could get better response out of the 755's using a
1.5CU ported enclosure down -3dB at (if my memory is correct) like 35Hz.
This is of course much easier and much less expensive than a horn to
recreate bass to 35Hz. I think the driver should be taken into context
when designing any type of enclosre. Just shoehorning (SP????) a speaker
into a cabinet would be silly. Many drivers fit only into one or maybe
two types of enclosures for the best results.
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "Moore, Larry Dean" <l-moore@onu.edu>
Subject: Back on line!
Date: Tue, 25 Aug 1998 09:58:34 -0400
Source: Sound Digest Archive v01.n400
Well gang, I'm back on line. I have taken a leave of absences from Lucent
Technologies and am now attending law school at Ohio Northern University.
If anyone wishes to contact me my new e-mail is l-moore@onu.edu I doubt
that I will have as much time as I had in the past; but, I will make an
effort to contribute to the list as time allows.
Currently, I am tweeking the Montford amplifiers which I spoke about prior
to leaving. Last night I ran across some bogus 5687s and faught with them
for about 3 hours before I discovered that one was the major source of my
problems sonically. Now, I have some 7119 in place and I'll really
starting to like them. In fact, this pushed me back to messing with the
crossover for the petite onken altec 511B/802 combo which I am now using.
Take care,
L.D. Moore
=========================================================================
From: tubesguy@mail.execpc.com (Patrick Currie)
Subject: Back online, w/ a pentode query
Date: Sun, 15 Feb 1998 16:16:35 -0500
Source: Sound Digest Archive v01.n193
Whew! The recent fix to keep spammers out inadvertently, perhaps, had
prevented me from posting to the list until I un- and then re-subscribed.
Thanks to Tom Ronan for the advice. Imagine how frustrating it was to have
people asking about how humans can generate a vacuum and not being able to
suggest seeking advice from Monica Lewinsky.
But on to matters audio. I am doing an amp using the 6AC7 as a driver, and
I need a screen supply. I would like to use one OD3 for both channels. Good
idea, or should the supplies be kept separate?
If I use the OD3, even for both channels, I am at the absolute lower limit
for current draw, since each of the screens draws only 2.5ma. Can I just
hang a bleeder resistor on the output of the OD3 to draw a little more
current through it?
I want to power the screens from a B+ supply of about 400v. Any
suggestions for the limiting resistor R if I draw a total of 20ma from the
OD3?
Any other suggestions for screen strategies also appreciated. I asked a
few days ago about SS current-regulator diodes, but got no takers.
TIA - Pat
Pat Currie (tubesguy@execpc.com)
=========================================================================
From: Hugh Dean <aspen@alphalink.com.au>
Subject: Re: Back online, w/ a pentode query
Date: Mon, 16 Feb 1998 09:22:33 +1100
Source: Sound Digest Archive v01.n193
Hi Patrick, you wrote:
>
> Whew! The recent fix to keep spammers out inadvertently, perhaps, had
> prevented me from posting to the list until I un- and then re-subscribed.
> Thanks to Tom Ronan for the advice. Imagine how frustrating it was to have
> people asking about how humans can generate a vacuum and not being able to
> suggest seeking advice from Monica Lewinsky.
A wonderful joke. Reminds of the one about Titanic...
> But on to matters audio. I am doing an amp using the 6AC7 as a driver, and
> I need a screen supply. I would like to use one OD3 for both channels. Good
> idea, or should the supplies be kept separate?
NO, keep them separate because the B+, where you support the OD3, will
be slightly modulated by the audio signal and thus you will suffer
crosstalk.
> If I use the OD3, even for both channels, I am at the absolute lower limit
> for current draw, since each of the screens draws only 2.5ma. Can I just
> hang a bleeder resistor on the output of the OD3 to draw a little more
> current through it?
Bleeder resistors are fine. However, the screen current is the go, and
according to Jean-Michel, varies almost linearly with plate current;
the voltage is not so important. So you would need to ensure that the
screen current can vary readily with the plate current, albeit with 150V
or so between them at all times.
> I want to power the screens from a B+ supply of about 400v. Any
> suggestions for the limiting resistor R if I draw a total of 20ma from the
> OD3?
Is the OD3 about 150V? I believe so. 400 - 150 is 250V, which is
dropped across the limiting resistor to ground. This would give you
12K5, rated at 5W. So choose about a 12W resistor for reasonable safety
margin.
Cheers,
Hugh R. Dean
Melbourne, Australia
> Any other suggestions for screen strategies also appreciated. I asked a
> few days ago about SS current-regulator diodes, but got no takers.
>
> TIA - Pat
>
> Pat Currie (tubesguy@execpc.com)
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: Back online, w/ a pentode query
Date: Mon, 16 Feb 1998 14:07:48 +0100 (MET)
Source: Sound Digest Archive v01.n197
At 09:22 16/02/1998 +1100, you wrote:
>Hi Patrick, you wrote:
>>
>> Whew! The recent fix to keep spammers out inadvertently, perhaps, had
>> prevented me from posting to the list until I un- and then re-subscribed.
>> Thanks to Tom Ronan for the advice. Imagine how frustrating it was to have
>> people asking about how humans can generate a vacuum and not being able to
>> suggest seeking advice from Monica Lewinsky.
>
>A wonderful joke. Reminds of the one about Titanic...
Let's come back to tube amp please! I give the example:
Let's take a classical single end plugged with buggle boys, let's call it Paula.
Then take a parallel feed working the tubes hot, call it Monica.
Then, let's take a powerfull push-pull, no Sovtek allowed there, but it
possess a weird kinked tube, call it William .
Which one is the most mellow sounding when playing?
(a really bad joke, I know...)
Best regards
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: "Frank Deutschmann" <fdeutsch@blackrock.com>
Subject: Re: Back online, w/ a pentode query
Date: Fri, 20 Feb 1998 12:39:49 -0500
Source: Sound Digest Archive v01.n197
On Feb 20, 6:23pm, Le Cleac'h J.-M. wrote:
> Hey, here comes the lost message!
> 5 days between the moment I send it and the moment it appears on the list,
> not bad! (The speed of electrons or is it the speed of electromagnetic
waves
> slow down a lot those days...)
The JoeNet is, it would seem, a rather poor filter; so much noise and ripple
in the passband, in both amplitude and phase response. But we love it
anyway....
Hey, would a thread about skiing at the Olympics be on topic? They did,
after all, have a vacuum tube in the downhill! (Their tube had lots of
compression, though.)
- -frank
=========================================================================
From: "Frank Deutschmann" <fdeutsch@blackrock.com>
Subject: Re: Back online, w/ a pentode query
Date: Fri, 20 Feb 1998 15:38:21 -0500
Source: Sound Digest Archive v01.n197
On Feb 20, 7:09pm, Le Cleac'h J.-M. wrote:
> >Hey, would a thread about skiing at the Olympics be on topic? They did,
> >after all, have a vacuum tube in the downhill! (Their tube had lots of
> >compression, though.)
>
> Sorry, this one is too tough for me...
I suppose your sports coverage is a little different, and perhaps there is a
translation aspect too. Anyway, in the American (CBS) (really pretty crappy)
coverage of the Downhill, the anouncer kept saying, "and there he goes, into
the Vacuum Tube...." What they were talking about is a section of the course
where the course has a fairly tight, banked turn (compression turn) into a
narrow section named the "vacuum tube". Searching on the web, I finally came
up with this site: http://www.shinmai.co.jp/oly-eng/kaijo/happo.htm (for all
the hyped IBM coverage, the best IBM and CBS can do is some basic stats on
the course). So I guess it was a bit obscure -- but its pretty funny that
the Japanese named a section of the Olympic downhill a "vacuum tube"!
- -frank
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: Back online, w/ a pentode query
Date: Fri, 20 Feb 1998 18:23:07 +0100 (MET)
Source: Sound Digest Archive v01.n197
At 14:07 16/02/1998 +0100, you wrote:
>Let's come back to tube amp please! I give the example:
<CUT>
Hey, here comes the lost message!
5 days between the moment I send it and the moment it appears on the list,
not bad! (The speed of electrons or is it the speed of electromagnetic waves
slow down a lot those days...)
Best regards,
Jean Michel Le Cleac'h
=========================================================================
From: davidbarnett@aristotle.net (David N. Barnett)
Subject: Re: Back online, w/ a pentode query
Date: Fri, 20 Feb 1998 18:49:19 GMT
Source: Sound Digest Archive v01.n197
On Mon, 16 Feb 1998 14:07:48 +0100 (MET), "Le Cleac'h J.-M."
<lecleach@cgi.ensmp.fr> wrote:
>Then take a parallel feed working the tubes hot, call it Monica.
I think this amp has a hum problem....
- --dnb
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: Back online, w/ a pentode query
Date: Fri, 20 Feb 1998 19:09:25 +0100 (MET)
Source: Sound Digest Archive v01.n197
At 12:39 20/02/1998 -0500, you wrote:
>On Feb 20, 6:23pm, Le Cleac'h J.-M. wrote:
>> Hey, here comes the lost message!
>> 5 days between the moment I send it and the moment it appears on the list,
>> not bad! (The speed of electrons or is it the speed of electromagnetic
>waves
>> slow down a lot those days...)
>
>The JoeNet is, it would seem, a rather poor filter; so much noise and ripple
>in the passband, in both amplitude and phase response.
Nice joke too!
>Hey, would a thread about skiing at the Olympics be on topic? They did,
>after all, have a vacuum tube in the downhill! (Their tube had lots of
>compression, though.)
Sorry, this one is too tough for me...
Best regards,
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: Stuart Williams <stuart@titus.u-strasbg.fr>
Subject: RE: Back online, w/ a pentode query
Date: Sat, 21 Feb 1998 09:38:03 +0100 (MET)
Source: Sound Digest Archive v01.n198
On Sat, 21 Feb 1998, Sellek, Grant (TSA) wrote:
> >From: Frank Deutschmann[SMTP:fdeutsch@blackrock.com]
> >a section of the course
> >where the course has a fairly tight, banked turn (compression turn) into a
> >narrow section named the "vacuum tube".... -- but its pretty funny that
> >the Japanese named a section of the Olympic downhill a "vacuum tube"!
>
> maybe they just got "venturi tube" wrong in naming it?
>
yeah, but if you hit a compression wrong in a tuck, you will find yourself
with a vacuum in your lungs.
Stuart
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@roads.sa.gov.au>
Subject: RE: Back online, w/ a pentode query
Date: Sat, 21 Feb 1998 14:53:57 +1030
Source: Sound Digest Archive v01.n198
>From: Frank Deutschmann[SMTP:fdeutsch@blackrock.com]
>a section of the course
>where the course has a fairly tight, banked turn (compression turn) into a
>narrow section named the "vacuum tube".... -- but its pretty funny that
>the Japanese named a section of the Olympic downhill a "vacuum tube"!
maybe they just got "venturi tube" wrong in naming it?
Grant Sellek
Adelaide, Australia
grant.sellek@roads.sa.gov.au
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: Back online, w/ a pentode query
Date: Mon, 23 Feb 1998 09:10:21 +0100 (MET)
Source: Sound Digest Archive v01.n198
At 15:38 20/02/1998 -0500, Frank Deutschmann wrote:
>On Feb 20, 7:09pm, Le Cleac'h J.-M. wrote:
>> Sorry, this one is too tough for me...
>I suppose your sports coverage is a little different, and perhaps there is a
>translation aspect too. Anyway, in the American (CBS) (really pretty crappy)
>coverage of the Downhill, the anouncer kept saying, "and there he goes, into
>the Vacuum Tube...."
OK, I get it now! (I knew "the tube" in waves surfing not that one)
Thanks for my vocabulary enrichment.
Best regards,
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: tubesguy@mail.chorus.net (Patrick Currie)
Subject: Back on the Joenet
Date: Tue, 3 Nov 1998 17:41:56 -0600
Source: Sound Digest Archive v01.n479
Phew, that was tough. A whole day off the list, due to a provider switch.
Did I miss anything?
My new email address should be in the header. If not, it is: tubesguy@chorus.net
- - Pat
=========================================================================
From: Joe Pledger <doodle@navicom.com>
Subject: Back & Thanks.
Date: Tue, 11 Nov 1997 08:53:23 -0800
Source: Sound Digest Archive v01.n105
Thanks Gang,
I stand corrected, must have been the Vogon...but without a fish in my
ear, I couldn't understand anything! ;-)
Good to be back!
Joe Pledger
=========================================================================
From: Jeremy Epstein <70664.154@compuserve.com>
Subject: Back To Mono!
Date: Tue, 21 Oct 1997 12:56:40 -0400
Source: Sound Digest Archive v01.n078
*NOTE : THIS POST HAS **NOTHING** TO DO WITH
NATURAL-SOUNDING RECORDINGS OF ACOUSTIC INSTRUMENTS*
I listen in mono all the time, much of my favorite music was recorded that way. I just flick the mon
o switch on my preamp, I have
a mono feed into a conventional stereo playback setup.
Last night I was enjoying my Japanese Chess Chuck Berry box set, "Very Good"
and I was fascinated by detail I heard in the mix - these records usually had a lead guitar and voca
l overdubbed on a backing track, and
some at-times-severe tape echo also mixed in. It was very easy to hear
which elements were on which generation, where the tape echo was
being manipulated (Oh Carol!) and what the drummer had for breakfast (Wheaties and bourbon.)
Apart from these records, there is a LOT of spatial info on mono discs -
and you don't have to be Phil or Brian to hear it!
Back to Mono!
- -j
=========================================================================
From: dball@esper.com (David Ball)
Subject: Re: Back To Mono!
Date: Tue, 21 Oct 1997 15:30:02 -0400
Source: Sound Digest Archive v01.n078
At 12:56 PM 10/21/97 -0400, Jeremy Epstein wrote:
>*NOTE : THIS POST HAS **NOTHING** TO DO WITH
>NATURAL-SOUNDING RECORDINGS OF ACOUSTIC INSTRUMENTS*
>
>I listen in mono all the time, much of my favorite music was recorded that
way. I just flick the mono switch on my preamp, I have
>a mono feed into a conventional stereo playback setup.
Darn near everything I listen to was originally recorded mono. I've got a
dedicated mono/78 rig in my upstairs where space is limited due to a large
number of 78s lining my walls--this is an old Fisher 500 mono receiver
playing through a Bozak kettle drum. Mono LPs and CDs play on my stereo rig
downstairs (mono switch flipped on the preamp) through the 2a3/Altec horn
rig. I like 'em both--they're just good for different things. The Fisher
is like a really really good radio with a turntable on it, and the 2A3/horn
setup has a more detailed and dynamic sound. But I have to admit that what
determines whether I listen in stereo or mono has a lot more to do with what
music I like than any internal philosophical struggle over "which is the
better way to listen."
Dave
=========================================================================
From: Dave Stagner <dstagner@icarus.net>
Subject: Bad 83?
Date: Mon, 23 Feb 1998 15:57:25 -0600 (CST)
Source: Sound Digest Archive v01.n199
How does one spot a bad 83 rectifier tube? I just got a tube tester that
uses one, and i think it's gone bad. When i turn it on, i can see the
purple glow through one of the test sockets, but it flickers irregularly,
and finally dies down to just a small spot of purple. I can't get good
test readings, either. When i put in a tube and press the test buttons, i
can see the rectifier flash, and sometimes go out completely. :(
I'm assuming i need a new tube here... does this sound right?
- -dave
Practice beautiful randomness and act kind of senseless.
<dstagner@icarus.net>
=========================================================================
From: Jeremy Epstein <jepstein@shwd.com>
Subject: Bad Playback
Date: Mon, 14 Dec 1998 10:01:20 -0500
Source: Sound Digest Archive v01.n537
I had the worst sound reproduction experience I can remember on Saturday
night. I went to a local production of Tchaikovsky's "Nutcracker Suite"
ballet, the dancers performed to a pre-recorded playback.
Ouch. First off, the level in the house was way beyond rock-concert,
totally overamped. Second, the playback system was not up to that level
of dynamics. Either something in the playback chain was overloaded,
playback was from a tape that had been made pinned into the red, or I
don't know what, anyway, every time there was a forte, didn't matter
which instrument, my ears bled. It could have been a harsh resonance in
the hall, too : the louder flute passages were particularly awful.
Such beautiful music, too, what a pity.
- -j
- --
=====================================
Jeremy Epstein .... jepstein@shwd.com
=====================================
=========================================================================
From: "Ken Dangerfield" <bpyakd@mail.island.net>
Subject: Re: Bad Playback
Date: Mon, 14 Dec 1998 13:23:14 -0800
Source: Sound Digest Archive v01.n538
On 14 Dec 98 Jeremy Epstein said:
> My five year old daughter was rapt (through the middle of the second
> act, when most grownups got fidgety too) so I consider it a
> successful evening. Decent punch, and very good cookies, at the
> reception.
Which is wonderful and makes the rest of it pale by comparison.
Regards,
Ken Dangerfield
=========================================================================
From: AnnaLogg@aol.com
Subject: Re: Bad Playback
Date: Mon, 14 Dec 1998 15:19:48 EST
Source: Sound Digest Archive v01.n538
In a message dated 98-12-14 10:24:31 EST, jepstein@shwd.com writes:
> I had the worst sound reproduction experience I can remember on Saturday
> night. I went to a local production of Tchaikovsky's "Nutcracker Suite"
> ballet, the dancers performed to a pre-recorded playback.
Actually, the *ballet* is called "The Nutcracker." The Nutcracker *Suite* is
just that -- a suite of excerpts from the complete ballet performed in concert
(actually, primarily on recordings) and just about every major orchestra has
at least 2 or 3 recordings of these excerpts (the "suite") to their credit.
But, on to the main topic:
>
> Ouch. First off, the level in the house was way beyond rock-concert,
> totally overamped. Second, the playback system was not up to that level
> of dynamics. Either something in the playback chain was overloaded,
> playback was from a tape that had been made pinned into the red, or I
> don't know what, anyway, every time there was a forte, didn't matter
> which instrument, my ears bled. It could have been a harsh resonance in
> the hall, too : the louder flute passages were particularly awful.
>
> Such beautiful music, too, what a pity.
>
Is this the first time you've heard it???? If so, may I suggest you continue
on down this road -- there are untold musical wonders awaiting you if you do.
But back to reality -- this is typical of the result we have come to in the
current cost of the arts. Most local ballet schools will mount a holiday
production of The Nutcracker because it is such popular fare at this time of
year, the kids love it, it gives the young dancers something to shine in and
it helps to promote their dance businesses. Yet unless possessing extensive
grant funding to foot the costs, few can afford a live orchestra. And, the
taped copies are usually an amateur effort administered by people who know
less than nothing about sound systems, much less about good sound. In other
words, they can't afford professional sound technicians either (even assuming
they could find one who wasn't stone deaf, anyway). I speak from personal
experience when I tell you that these productions are largely the work of
volunteers, and the artistic directors have to pretty much work with what they
have given to them.
So, Jeremy, since you undoubtedly found other pleasurable merit in the event,
why don't you volunteer to assist with next year's production and see to it
that the music reproduction is worthy of the effort? It might be fun, not to
mention very rewarding as well as enlightening!
Happy holidays,
Anna
=========================================================================
From: Jeremy Epstein <jepstein@shwd.com>
Subject: Re: Bad Playback
Date: Mon, 14 Dec 1998 15:43:41 -0500
Source: Sound Digest Archive v01.n538
AnnaLogg@aol.com wrote:
>
> In a message dated 98-12-14 10:24:31 EST, jepstein@shwd.com writes:
>
> > I had the worst sound reproduction experience I can remember on Saturday
> > night. I went to a local production of Tchaikovsky's "Nutcracker Suite"
> > ballet, the dancers performed to a pre-recorded playback.
>
> Actually, the *ballet* is called "The Nutcracker."
N.B.
> But, on to the main topic:
> > Such beautiful music, too, what a pity.
> >
> Is this the first time you've heard it???? If so, may I suggest you continue
> on down this road -- there are untold musical wonders awaiting you if you do.
Oh, no, one could hardly have missed the more familiar melodies from
this ballet, but as you indirectly pointed out, the full ballet has more
music than is commonly heard, and I found the variety of themes (and
their beauty) remarkable. It was a nice (taped) performance, too, don't
know whose.
Which road are you suggesting, Anna? Music for ballet? Tchaikovsky?
Local productions of famous Christmas works?
I must confess my favorite music composed for dance is probably "The
Catherine Wheel," David Byrne for Twyla Tharp, but that's sorta by
default. Not a big classical ballet fan, I'm afraid! More reason why I
was disappointed in the music on Saturday - I wasn't loving the dance
that much.
> But back to reality -- this is typical of the result we have come to in the
> current cost of the arts. Most local ballet schools will mount a holiday
> production of The Nutcracker because it is such popular fare at this time of
> year, the kids love it, it gives the young dancers something to shine in and
> it helps to promote their dance businesses. Yet unless possessing extensive
> grant funding to foot the costs, few can afford a live orchestra.
This was the case : it was a local ballet, many strudents were onstage
and performed wonderfully.
> And, the
> taped copies are usually an amateur effort administered by people who know
> less than nothing about sound systems, much less about good sound. In other
> words, they can't afford professional sound technicians either (even assuming
> they could find one who wasn't stone deaf, anyway).
I think the latter was the case : Someone from Something Studio got
program credit.
> I speak from personal
> experience when I tell you that these productions are largely the work of
> volunteers, and the artistic directors have to pretty much work with what they
> have given to them.
>
> So, Jeremy, since you undoubtedly found other pleasurable merit in the event,
Well, see my food review below.
> why don't you volunteer to assist with next year's production and see to it
> that the music reproduction is worthy of the effort? It might be fun, not to
> mention very rewarding as well as enlightening!
Good suggestion BUT : it was presented at a college auditorium, I expect
that I'd be impinging on someones turf or worse, acing a student worker
out of a job if I did so. Also why I didn't try to complain to someone :
they'd either be a volunteer doing the best they can, or a fixture who
does it the way he always does it.
Weak excuses perhaps. I'll mull it over.
My five year old daughter was rapt (through the middle of the second
act, when most grownups got fidgety too) so I consider it a successful
evening. Decent punch, and very good cookies, at the reception.
- -j
- --
=====================================
Jeremy Epstein .... jepstein@shwd.com
=====================================
=========================================================================
From: Dave Stagner <dstagner@icarus.net>
Subject: Re: Bad Playback
Date: Mon, 14 Dec 1998 16:52:54 -0600 (CST)
Source: Sound Digest Archive v01.n538
On Mon, 14 Dec 1998, Ken Dangerfield wrote:
> On 14 Dec 98 Jeremy Epstein said:
>
> > My five year old daughter was rapt (through the middle of the second
> > act, when most grownups got fidgety too) so I consider it a
> > successful evening. Decent punch, and very good cookies, at the
> > reception.
>
> Which is wonderful and makes the rest of it pale by comparison.
Heh. The other day (after getting my system in fairly decent shape again,
thanks to a new power supply for the DAC), i put on "The Magic Flute" for
the kids. My daughter the audiophile loved it. Her brother hated it, and
kept demanding to listen to Sesame Street. Eventually, he fell asleep
during an aria. Typical. :}
- -dave
Practice beautiful randomness and act kind of senseless.
<dstagner@icarus.net>
=========================================================================
From: AnnaLogg@aol.com
Subject: Re: Bad Playback
Date: Mon, 14 Dec 1998 16:58:45 EST
Source: Sound Digest Archive v01.n538
In a message dated 98-12-14 15:53:35 EST, jepstein@shwd.com writes:
> Oh, no, one could hardly have missed the more familiar melodies from
> this ballet, but as you indirectly pointed out, the full ballet has more
> music than is commonly heard, and I found the variety of themes (and
> their beauty) remarkable. It was a nice (taped) performance, too, don't
> know whose.
>
> Which road are you suggesting, Anna? Music for ballet? Tchaikovsky?
> Local productions of famous Christmas works?
Music for classical ballet in general, but specifically Tchaikovsky -- that
is, if you have not heard the full scores for Sleeping Beauty and/or Swan
Lake, for example. Also not to be left out, but of a much different flavor,
are the big Stravinsky works, "The Firebird" and "Rite Of Spring." (Try
*those* on your Wurlitzers, guys!) There is much, much more in the ballet
realm, and it is usually well-recorded and orchestrally both lush and
viscerally dynamic in a way that no other music quite matches, with the
possible exception of grand opera.
As for The Nutcracker, growing up I too heard only the suite, on records,
until I attended my first production by the New York City Ballet under the
direction of George Balanchine back in the early '60's. I recall being
especially bowled over by the music of the christmas tree scene (not to
mention the scenery effects) and then smitten by the Waltz of the Snowflakes
with it's hauntingly beautiful choral overlay (which so magically suggests the
soughing of the wind through the pine trees!), together with the whirling snow
that proceeded to fall more and more heavily as the dance progressed. It was,
to me, the ultimate in fantasy. No amount of filmed "special effects" can
quite compare to the magical impact of a well-done stage production.
For nearly 20 years after that, I never missed a NYC Ballet season, and
enjoyed watching costume and choreographic changes and refinements over the
ensuing years. It never failed to work it's magic on the child within.
If you can find an LP of it (and it's fairly common) I recommend the
Ansermet/Suisse Romande on London, a 2-record set, which I think has a special
theatricality. Otherwise, Dorati did it for Mercury, which would be my second
choice. But there are many others, and none really bad.
>
> I must confess my favorite music composed for dance is probably "The
> Catherine Wheel," David Byrne for Twyla Tharp, but that's sorta by
> default. Not a big classical ballet fan, I'm afraid! More reason why I
> was disappointed in the music on Saturday - I wasn't loving the dance
> that much.
>
Well, beauty is in the eye of the beholder. Just remember that contemporary
dance has its roots in classical movement and training. It is perhaps the most
interesting art form because prior to the advent of film, it survived via
tradition and legacy. Imagine, these great huge ballets being preserved only
through direct handing down from dancer to dancer as they evolved from
performer to teacher. If only we had a film record of that first Swan Lake or
that first Rite Of Spring (both of which were horrendously castigated by the
critics of the day)! If only we had a film record of the original choreography
of these 19th century masterpieces, for as you might expect, much has been
lost through the reliance on memory. Indeed, this is why the defection of
Nureyev was of such cultural importance to western dance -- he brought with
him a wealth of schooling and knowledge of classical choreographic tradition
that had not been seen outside Russia for many decades.
Getting back to Piotr Ilyitch for just a moment, it might interest you to know
that all that glorious music was composed to fit the choreography already
devised by the reigning choreographer, Petipa, not the other way around!
Yes, dance -- all of dance -- has a colorful and interesting history . . .
Well, forgive me my passion here. (Just don't anybody mention *opera*
<gasp!!>)
Happy holidays,
Valerie Ann(a)
=========================================================================
From: Kalman Rubinson <kr4@is2.nyu.edu>
Subject: Re: Bad Playback
Date: Mon, 14 Dec 1998 17:49:45 -0500 (EST)
Source: Sound Digest Archive v01.n538
On Mon, 14 Dec 1998 AnnaLogg@aol.com wrote:
> Music for classical ballet in general, but specifically Tchaikovsky -- that
> is, if you have not heard the full scores for Sleeping Beauty and/or Swan
> Lake, for example. Also not to be left out, but of a much different flavor,
> are the big Stravinsky works, "The Firebird" and "Rite Of Spring." (Try
> *those* on your Wurlitzers, guys!) There is much, much more in the ballet
> realm, and it is usually well-recorded and orchestrally both lush and
> viscerally dynamic in a way that no other music quite matches, with the
> possible exception of grand opera.
OK. Let me put in a suggestion for Prokofiev's Romeo and
Juliet (Maazel, Cleveland).
Kal
=========================================================================
From: AnnaLogg@aol.com
Subject: Re: Bad Playback
Date: Mon, 14 Dec 1998 18:25:39 EST
Source: Sound Digest Archive v01.n538
In a message dated 98-12-14 17:49:52 EST, kr4@is2.nyu.edu writes:
> OK. Let me put in a suggestion for Prokofiev's Romeo and
> Juliet (Maazel, Cleveland).
>
Yes!!! Breathtaking dramatic imagery and the same kind of evocative orchestral
depth and color as, say, Scheherezade. Plus melodies to tear your heart out .
. .
Happy holidays,
Valerie Ann(a)
=========================================================================
From: rlahlum@juno.com (Ross J Lahlum)
Subject: Re: Bad Playback
Date: Mon, 14 Dec 1998 22:37:33 -0600
Source: Sound Digest Archive v01.n539
That reminds me of my first recording of the Nutcracker -
William Steinberg & Pittsburgh on Command Classics
(1967 "audiophile" 35 mm recording). Finally found it & gave it
a relisten after many years. Kind of disappointing compared to
the records I think sound good now, since I must have worn it
out the first year on my kid-hi-fi BSR. Wish I could find a really good
copy.
But for me the magic of the piece was planted in my soul
at the tempos Steinberg chose, and any other version I hear (and I've
gathered 5 or 6 other interpretations over the years of binges at used
record stores, garage sales & friends of the library sales) no matter how
good, leaves me wishing it had been done Steinberg's way because that's
the way my mind plays it back to me. Even if it's not the critics'
definitive
version, it's the quickest route for me to get to feeling like a kid at
Christmas.
- -RL
On Mon, 14 Dec 1998 13:23:14 -0800 "Ken Dangerfield"
<bpyakd@mail.island.net> writes:
>On 14 Dec 98 Jeremy Epstein said:
>
>> My five year old daughter was rapt (through the middle of the
>second
>> act, when most grownups got fidgety too) so I consider it a
>> successful evening. Decent punch, and very good cookies, at the
>> reception.
>
>Which is wonderful and makes the rest of it pale by comparison.
>
>Regards,
>Ken Dangerfield
>
___________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
or call Juno at (800) 654-JUNO [654-5866]
=========================================================================
From: Kalman Rubinson <kr4@is2.nyu.edu>
Subject: Re: Bad Playback
Date: Tue, 15 Dec 1998 09:17:40 -0500 (EST)
Source: Sound Digest Archive v01.n539
On Mon, 14 Dec 1998, Ross J Lahlum wrote:
> But for me the magic of the piece was planted in my soul
> at the tempos Steinberg chose, and any other version I hear (and I've
> gathered 5 or 6 other interpretations over the years of binges at used
> record stores, garage sales & friends of the library sales) no matter how
> good, leaves me wishing it had been done Steinberg's way because that's
> the way my mind plays it back to me. Even if it's not the critics'
> definitive
> version, it's the quickest route for me to get to feeling like a kid at
> Christmas.
Isn't it amazing how we are imprinted by an early exposure?
I have many such connections to performances that I now
accept as far from optimum but which, nonetheless, are among
my favorites because they are the way I learned the piece.
Kal
=========================================================================
From: "Eric Weitzman" <eweitzman@acm.org>
Subject: balance pot for PP amp with shared cathode resistor?
Date: Sun, 11 Oct 1998 21:56:54 -0700
Source: Sound Digest Archive v01.n450
I have a PP 6BQ5 amp that uses cathode bias. It has a tertiary winding
on the OPT in the cathode circuit providing feedback, and a 130 ohm (3
watt) cathode resistor bypassed by a 25uF cap on the center tap of
this winding providing the bias.
+----------Cathode of tube 1
|
+-)||
130 )||
GND-+--R--+-----)||
| | )||
+--C--+ +-)||
25 |
+----------Cathode of tube 2
How can I modify this circuit so that I can adjust the bias
of both tubes with a single pot? I bet it can't be done...
If I was to remove the tertiary winding from the circuit (and provide
feedback off of the secondary winding) and put a balance pot as shown
below, how would I calculate the bypass cap(s)? 25uF? 50uF? 12.5uF?
GND----C------+----------Cathode of tube 1
|
\
120 /
GND----R----->\ 20 ohm pot
/
\
|
GND----C------+----------Cathode of tube 2
Finally, if I keep the R of the pot low, I can use a cheap cermet
trimmer with a low power rating. Is using such a device going to
hurt the sound? I have four of these output stages and so I'd like
to keep the number and cost of the pots down.
Thanks,
- -Eric
=========================================================================
From: peterca@ento.csiro.au
Subject: Re: balance pot for PP amp with shared cathode resistor?
Date: Tue, 13 Oct 1998 10:14:52 +1000 (EST)
Source: Sound Digest Archive v01.n451
>I have a PP 6BQ5 amp that uses cathode bias. It has a tertiary winding
>on the OPT in the cathode circuit providing feedback, and a 130 ohm (3
>watt) cathode resistor bypassed by a 25uF cap on the center tap of
>this winding providing the bias.
>
>
> +----------Cathode of tube 1
> |
> +-)||
> 130 )||
>GND-+--R--+-----)||
> | | )||
> +--C--+ +-)||
> 25 |
> +----------Cathode of tube 2
>
>How can I modify this circuit so that I can adjust the bias
>of both tubes with a single pot? I bet it can't be done...
If the center tap of the actual tertiary winding is accessable (ie. you
have a loop of the wire or two wires coming out of the transformer) I would
cut the wire to get the two halves of the winding separate. Then I would
put a 260 ohm/2W resistor (IE 2x130ohm) from each one to ground and bypass
both with caps. With no other changes to the circuit you will get
automatic self bias. DC feedback will keep the DC balanced in the
transformer. This might be an improvement in itself if there are any
significant differences between the PP pairs now. This keeps your
modifications simple and cheap because the biasing, B+ and feedback
arrangements are unaltered, just better balanced for DC. The only hitch
would be whether you have room to accomodate two resistors and caps rather
than one of each.
Dr. Peter Campbell (peterca@ento.csiro.au)
Div. Entomology, C.S.I.R.O. Ph.61-2-62464053 or -62464158 (w)
Box 1700 Canberra A.C.T. 2601 61-2-62516213 (h)
Australia 61-2-62464173 (fax)
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: balance pot for PP amp with shared cathode resistor?
Date: Mon, 12 Oct 1998 21:25:52 -0700
Source: Sound Digest Archive v01.n452
Can't pass this one up; I've fooled with a few PP BQ5s in the old
days...
Eric Weitzman wrote:
>
> I have a PP 6BQ5 amp that uses cathode bias. It has a tertiary winding
> on the OPT in the cathode circuit providing feedback, and a 130 ohm (3
> watt) cathode resistor bypassed by a 25uF cap on the center tap of
> this winding providing the bias.
>
> +----------Cathode of tube 1
> |
> +-)||
> 130 )||
> GND-+--R--+-----)||
> | | )||
> +--C--+ +-)||
> 25 |
> +----------Cathode of tube 2
>
> How can I modify this circuit so that I can adjust the bias
> of both tubes with a single pot? I bet it can't be done...
Step one: before you do anything else, replace that wimpy 3-w
resistor. Every 6BQ5 amp I've ever seen that was not working, was not
working because the cheap low-wattage cathode resistor had fried
itself. SE, PP, low-fi, hi-fi, or guitar, doesn't matter - it was a
cheap tube, made for cheap circuits and they used cheap parts. (OK, I
exaggerate a little - but I've seen it an awful lot of times!)
Step two: Look at a Williamson circuit. The original, I mean. It shows
you how to do this. Don't know what you were betting, but you lost!
:^) The Williamson also offers a separate adjustment for total
current as well as current balance.
> If I was to remove the tertiary winding from the circuit (and provide
> feedback off of the secondary winding) and put a balance pot as shown
> below, how would I calculate the bypass cap(s)? 25uF? 50uF? 12.5uF?
>
> GND----C------+----------Cathode of tube 1
> |
> \
> 120 /
> GND----R----->\ 20 ohm pot
> /
> \
> |
> GND----C------+----------Cathode of tube 2
Is this in pentode mode or triode mode? RDH4 has a method for
calculating cathode bypass, but it depends on the circuit. Triode caps
are always pretty close to twice what you'd think from the cathode
resistor alone, but pentodes are as much as 13 times I think (didn't
check - too lazy tonight). In either case, I doubt that the 25uF job
did much at low frequencies ... speaking of which, George Wright has
suggested in a similar situation that the two cathodes could be tied
together with a small cap - 1 uF or so - to improve balance at high
frequencies where the 'lytics are likely not performing well.
> Finally, if I keep the R of the pot low, I can use a cheap cermet
> trimmer with a low power rating. Is using such a device going to
> hurt the sound? I have four of these output stages and so I'd like
> to keep the number and cost of the pots down.
See above comments about power ratings.
- -Paul Joppa
=========================================================================
From: Ishmael349@aol.com
Subject: Re: Ban drinking in public places?
Date: Tue, 12 Jan 1999 09:31:16 EST
Source: Sound Digest Archive v01.n570
Thank you. The real issue here is too many people seem anxious to force other
people to suffer as long as they do not have to. I say you guys have
seriously limited my personal pleasure by allowing smoking to banned in
restaurants and airplanes but are not willing to give up dring in public
places to cut down on the national death toll. If that ain't hipocracy -
what is?
HR
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: Ban drinking in public places?
Date: Tue, 12 Jan 1999 16:18:36
Source: Sound Digest Archive v01.n570
A 09:31 AM 1/12/99 EST, Ishmael349@aol.com a écrit :
>Thank you. The real issue here is too many people seem anxious to force
other
>people to suffer as long as they do not have to. I say you guys have
>seriously limited my personal pleasure by allowing smoking to banned in
>restaurants and airplanes but are not willing to give up dring in public
>places to cut down on the national death toll. If that ain't hipocracy -
>what is?
>
>HR
>
>
One important difference between tobacco and alcohol is that moderate
alcohol use is beneficial, whereas no amount of tobacco use confers
benefits. Moderate drinkers outlive teetotallers, whereas any amount of
smoking reduces life expectancy. Regarding public drinking leading to road
accidents, the analogy is a poor one. There are blood alcohol limits for
drivers, and sanctions against those who are caught violating these.
Another important difference is that moderate drinking in a public place
does not infringe on my rights, whereas smoking does. There is no "passive
drinking" that corresponds to "passive smoking."
dbk
=========================================================================
From: Joe Pledger <doodle@navicom.com>
Subject: Re: Ban drinking in public places?
Date: Tue, 12 Jan 1999 23:38:09 -0800
Source: Sound Digest Archive v01.n571
Sellek, Grant (TSA) wrote:
>
> Date: Tue, 12 Jan 1999 16:18:36
> From: "David B. Klein" <dklein@microtec.net>
> Subject: Re: Ban drinking in public places?
>
> Moderate drinkers outlive teetotallers, whereas any amount of
> smoking reduces life expectancy.
>
> --------end quote-----------
>
> As I recall, the studies that came to the above conclusion about alcohol
> were widely publicised for years (need I mention by whom?), before follow-up
> studies showed that the "teetotaller" group included reformed alcoholics,
> which totally biased the result. When the AA types were taken out of the
> teetotaller groups, the result was reversed.
>
> Further studies have since been undertaken to demonstrate that moderate
> drinking has no effect on health (need I mention by whom?).
>
> At some point I start to walk away from arguments (and that is what they
> are, not discussions) about statistical studies.
>
> Grant
>
> Grant Sellek
> Adelaide, Australia
> grant.sellek@roads.sa.gov.au
Well,
The last time I was in Spain, entered a resturant and they plunked down
an unmarked btl of red (no water) without asking, and gave me a menu!
One glass of red per day is fine! Trouble is one tends to do that and go
on...and on..Ah! Spain!
Regards,
M513S
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: Ban drinking in public places?
Date: Wed, 13 Jan 1999 04:20:20 -0500
Source: Sound Digest Archive v01.n571
David Barnett wrote:
>
> On Wed, 13 Jan 1999 07:50:20 +0000 (BST), Simon Busbridge
> <S.C.Busbridge@bton.ac.uk> wrote:
>
> >What has this got to do with hi-fi?
>
> That one's easy -- smoking will damage the panels in my old QUAD
> Electrostatic Loudspeakers, but I can drink in the same room with them
> and they'll be safe unless I trip over them.... <G>
>
From another perspective, the ESLs will probably precipitate smoke
particles out of the air (to their detriment, however).
Cheers,
David
=========================================================================
From: Simon Busbridge <S.C.Busbridge@bton.ac.uk>
Subject: Re: Ban drinking in public places?
Date: Wed, 13 Jan 1999 07:50:20 +0000 (BST)
Source: Sound Digest Archive v01.n571
What has this got to do with hi-fi?
Dr Simon Busbridge
School of Engineering
University of Brighton
Lewes Road
Moulsecoomb
Brighton BN2 4GJ
UNITED KINGDOM
Tel: 0044 (0)1273 642542
Fax: 0044 (0)1273 642327/642301
e-mail: s.c.busbridge@bton.ac.uk, scbusbridge@hotmail.com
On Tue, 12 Jan 1999 Ishmael349@aol.com wrote:
> Thank you. The real issue here is too many people seem anxious to force other
> people to suffer as long as they do not have to. I say you guys have
> seriously limited my personal pleasure by allowing smoking to banned in
> restaurants and airplanes but are not willing to give up dring in public
> places to cut down on the national death toll. If that ain't hipocracy -
> what is?
>
> HR
>
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: Ban drinking in public places?
Date: Wed, 13 Jan 1999 08:14:20 GMT
Source: Sound Digest Archive v01.n571
On Wed, 13 Jan 1999 07:50:20 +0000 (BST), Simon Busbridge
<S.C.Busbridge@bton.ac.uk> wrote:
>What has this got to do with hi-fi?
That one's easy -- smoking will damage the panels in my old QUAD
Electrostatic Loudspeakers, but I can drink in the same room with them
and they'll be safe unless I trip over them.... <G>
- --dnb
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@roads.sa.gov.au>
Subject: Ban drinking in public places?
Date: Wed, 13 Jan 1999 16:31:49 +1030
Source: Sound Digest Archive v01.n571
Date: Tue, 12 Jan 1999 16:18:36
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: Ban drinking in public places?
Moderate drinkers outlive teetotallers, whereas any amount of
smoking reduces life expectancy.
- --------end quote-----------
As I recall, the studies that came to the above conclusion about alcohol
were widely publicised for years (need I mention by whom?), before follow-up
studies showed that the "teetotaller" group included reformed alcoholics,
which totally biased the result. When the AA types were taken out of the
teetotaller groups, the result was reversed.
Further studies have since been undertaken to demonstrate that moderate
drinking has no effect on health (need I mention by whom?).
At some point I start to walk away from arguments (and that is what they
are, not discussions) about statistical studies.
Grant
Grant Sellek
Adelaide, Australia
grant.sellek@roads.sa.gov.au
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: Ban drinking in public places?
Date: Wed, 13 Jan 1999 17:01:27 +0100
Source: Sound Digest Archive v01.n572
please discuss without involving joes
Guido
At 09:31 12-1-99 EST, Ishmael349@aol.com wrote:
>Thank you. The real issue here is too many people seem anxious to force
other
>people to suffer as long as they do not have to. I say you guys have
>seriously limited my personal pleasure by allowing smoking to banned in
>restaurants and airplanes but are not willing to give up dring in public
>places to cut down on the national death toll. If that ain't hipocracy -
>what is?
>
>HR
>
>
=========================================================================
From: Ishmael349@aol.com
Subject: Re: Ban drinking in restaurants?
Date: Mon, 11 Jan 1999 15:47:06 EST
Source: Sound Digest Archive v01.n567
If I smoke a cigerette after dinner it will not be the cause of me hitting a
school child with my car on the way home? The wine I had with dinner will.
Which of you non-smokers are ready to ban drinking in restaurants? I
personally would prefer to not smell alcohol while I eat. Is that reason
enough for you to not have wine with your meal? Please, tell me your concern
for the national health and welfare is great enough for you to give up
alcohol.
HR
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: Ban drinking in restaurants?
Date: Tue, 12 Jan 1999 19:53:11 GMT
Source: Sound Digest Archive v01.n570
On Mon, 11 Jan 1999 15:47:06 EST, Ishmael349@aol.com wrote:
>If I smoke a cigerette after dinner it will not be the cause of me hitting a
>school child with my car on the way home?
Most people can take one drink and stop. No one smokes one cigarette.
Alcoholics are a minority of the total number of people who drink, all
cigarette smokers are addicts.
- --dnb
=========================================================================
From: Jeremy Epstein <jepstein@shwd.com>
Subject: Bantying About Opinion Etc.
Date: Mon, 30 Nov 1998 15:56:52 -0500
Source: Sound Digest Archive v01.n510
Without entering into a whole lotta debate over pseudoscience,
charlatanism, shamanism and the like, I _would_ like to discuss the
place I see for "I like this better than that" types of debate.
I'm a busy guy when I'm at home. I've got a wife (talk about a full-time
job!) and a kid, and they both get a little huffy when I hide in the
basement sniffing solder fumes for hours on end, all weekend, every
night. Trust me, I know this from experience. So I have to leave SOME of
the xPerimentation to my esteemed collegues. I try to hold up my end by
being as helpful as I can around here, but as a general rule, I owe you
one. And I will probably never catch up.
Now take a guy like Slagle, who tries more tweaks in a day than I do in
a year. He has a setup whereby he can try this, that or the other thing
just by twisting a Variac and moving a clip lead. (I will point out that
he has learned nothing whatsoever about shielding or layout or UL
approval, those of you who have visited him will know what I'm talking
about.)
A guy like me has no choice but to listen to a guy like him. He says,
"low DCR in the power supply," or "try the mercury rectifiers, at worst
they look tres cool, at best they sound great," and he has been there
and done that. Is he oversimplifying? Most likely. Will I have fun
building and listening to equipment using his design principles and
prejudices? Definitely. Will I ever design and build gear for a living?
Will I discover the Rosetta Stone of Audio Reproduction? Um, doubtful.
I still think all the Joes are really cool, though. Myself included.
Even if some of us are totally FOS, myself included.
- -j
- --
=====================================
Jeremy Epstein .... jepstein@shwd.com
=====================================
=========================================================================
From: "Doc B." <bottlehead@silverlink.net>
Subject: Bantying about opinion instead of listening and learning for ourselves
Date: Mon, 30 Nov 1998 09:15:46 -0800
Source: Sound Digest Archive v01.n509
The very best reason to buy Magnaquest is that they are
>cheaper than Tango or Tamura, certainly not better. Just look at the band
width
>for starters.
The fact that MagneQuest products are less expensive for equal or better
performance than the two very good, quite different competitive products
mentioned here is indeed a very good reason to consider their purchase, but
hardly the only one.
Do, look at the bandwidth, the power bandwidth. It will become apparent that
the MagneQuest transformers exhibit excellent performance at low
frequencies.
It's very interesting to attend one of Mike L.'s talks at VSAC. The question
always comes up "What about the importance of frequency response
measurements? "
As Mike points out, this is really about item number 20 on the list for
determination of the best transformer for a given application.
It is much more likely that measured inductance at low frequencies and
higher power levels will come to play. If you must buy based on what are, as
Lynn points out, basically rather gross measurements, then at least use as
many different specifications as possible to make a decision, with
inductance as one of the more important factors.
Also, consider the manufacturer's rationale in their selection of materials.
Is it best to use permalloy in a conventional airgapped transformer,
allowing direct coupling to the plate of the output tube, but where where
its high permeability is hampered by the problem of saturation from DC, or
in an interleaved transformer designed for parallel feed, where the tube is
cap coupled, but the permalloy is used to its best advantage?
Is it better to pot a transformer, which is indeed quite attractive and may
help to reduce "singing", at the expense of risking distortion of the
laminations by the use of potting material that does not penetrate as well
as some waxes and varnishes, and adds more insulating materials of perhaps
questionable DA and DF to potentially color the sound?
And if you must use frequency response as a factor in your choice of
transformers, perhaps because this is a measurement easily understood not
only by experienced designers, but also by the cool new folks who are
swelling the bottlehead ranks lately, please do consider that manufacturers
published response figures vary from +- 1 dB to +- 3 dB, which makes side by
side comparisons of these figures fairly useless.
I agree that the idea of Mike feeling the need to redesign any competitor's
current production is indeed quite silly, and I suggest that Lynn's point
that designers would be compelled to charge for their time if asked to work
on an existing design was pulled quite far out of context here.
And as always, I suggest that using your own ears is the only true way to
determine what works for you.
Doc B.
=========================================================================
From: "Doc B." <bottlehead@silverlink.net>
Subject: Re: Bantying about opinion instead of listening and learning for ourselves
Date: Mon, 30 Nov 1998 12:48:52 -0800
Source: Sound Digest Archive v01.n510
>Hi Doc,
>
>I agree absolutely that we should choose on the basis of our experince
which is
>exactly what I did, and chose Tangos.
This is excellent, you have listened and made a choice that pleases you. But
why the knee jerk reaction to the supposition posted by Lynn? He did not say
that either of those products *needed* to be redesigned, he was just using
them for the sake of example to make a different point, suggesting that
anyone who would ask for one manufacturer to modify another manufacturer's
product should be prepared to pay for the designer's time.
He obviously made a choice of brands which rubbed you the wrong way. Why you
feel compelled to turn this into your own partisan diatribe is your own
business, I guess.
But hell, don't be surprised that I defend my turf, that's my job.
>
>There are let's face it partisans on this list of manufacturers who
disguise
>their partisanship in supposedly objective language.
My post was certainly not objective. I can't imagine why you took it that
way. I am the largest MagneQuest distributor because I believe it is an
excellent product, and I have never disguised this fact. If I posted in such
a manner as to make it appear objective, perhaps you have mistaken my
concern to not bash a competitive product in a crude manner for some sort of
patronizing tone.
Also some of these
>partisans on this list manufacture amplifiers for commerical sale using one
>brand of transformer or another. So, I hardly think it is objective to say
that
>Tango or Tamura transformers are in need of redesign by Mr LeFevre who by
all
>accounts has only been making transformeres for a few years whereas the
Japanse
>brands have been at it for many decades!
To begin with Mike's archives go back to 1934 and includes designs from
WE,Peerless, Acrosound,Dynaco, Freed, Triad, etc.
Secondly, Mike's capabilities show in his product and innovation. Take
parallel feed as a single example of a very creative, informed approach to
Mike's design qualifications.
Thirdly, every transformer that leaves MagneQuest has been handled by Mike
personally, a level of personalized quality control which is probably not
approached by the manufacturers you mention.
Lastly, nobody said Mike needed to redesign any competitor's product except
you.
>
>While I may have suggested bandwidth is a starting point for comparison, I
did
>not suggest in any way that it was the end of the story. On the other hand
you
>point to bass response amongst other supposed criteria in which Magnaquest
>transformers are supposed to exceed the capacities of the sorry Tango or
>Tamuras. Surely in itself bass is not even a particularly important
criterion? I
>say HF extension, you say bass. I know what I choose and why.
>
>My own opinion is that as a inbuilt crowd pleaser for audio illiterates,
bass
>response is a very successful selling point.
So now you are attempting to insult my customers? How childish! This kind of
opinionated blanket statement after suggesting that people compare technical
specs is evasive.
We're talking about a broad product line. There are MagneQuest transformers
that are -1dB at 140kHz. The RS series certainly matches the Tango products
in terms of top end response, and the small EXO series parallel feed
transformers are -1dB at 47 kHz and possess bass articulation superior to
any conventional air gapped SE transformers to boot.
Bass performance is indeed an important criteria, but not only in terms of
frequency response. The primary L of the transformer is critical to the
phase response of the bass. It is not a quantity issue, but rather an issue
of quality. It may well be that this is why Stereo Sound chose MagneQuest SE
and push pull transformers over the brands you have mentioned in their
subjective listening tests.
By the way, if you are using the response figures published in the
MagneQuest product literature as your guide, they are much more conservative
than what is actually measured. This is largely for the reason stated
before, Mike feels that frequency response specs are a small contributor to
what makes a transformer sound good.
But I suppose we are talking
>American "taste" (?)
I think here you have pretty much completely embarrased yourself. That is a
counterproductive way to make a point.
I would be interested in continuing this discussion on a technical level,
because I am quite confident it would be useful to joelist members. If you
would be interested in a competent technical discussion of useful criteria
for the selection of output transformers, please let me know, and I will ask
some of my associates to contribute to the discussion.
Doc B.
=========================================================================
From: "Doc B." <bottlehead@silverlink.net>
Subject: Re: Bantying about opinion instead of listening and learning for ourselves
Date: Mon, 30 Nov 1998 12:55:39 -0800
Source: Sound Digest Archive v01.n510
Why have you directed this to me?
Lynn is exceedingly competent, and able to answer your questions if you are
having trouble grasping any of his thoughts.
Doc B.
www.bottlehead.com
- -----Original Message-----
From: Mark Donen <soledadd@worldnet.att.net>
To: Doc B. <bottlehead@silverlink.net>
Cc: sound@deliverator.io.com <sound@deliverator.io.com>
Date: Monday, November 30, 1998 10:49 AM
Subject: Re: Bantying about opinion instead of listening and learning for
ourselves
>Dear Doc,
>
>I also note with interest how Mr. Olson has changed his views on horn
speakers
>since a long series of posts about a year ago. Naturally, I think it is
salutary
>that he has changed his mind, awakening so to speak from his dogmatic
slumber. I
>recall how it was argued at great length why horns cannot work well, by any
>objective measured criteria. Are we to believe that Messieurs Exemplar have
>overcome these problems, or that Mr. Olson has heard some good horns. My
>suspicion is that the measured problems Mr. Olson refers to persist and
that
>their horns just sound good. Bollocks to "objective" criteria!
>
>You have to correlate data to taste and measure the right thing. I am sure
Mr.
>Olson Ariel's measure great, but since he's enamored of the BBC house sound
I
>guess they wouldn't disturb a Brit granny slumping slowly sideways in a
>semiconscious stupor on her sofa listening to the Proms on Radio 3! There
are
>those who think Quad ESLs and LS3/5A are the greatest speakers in the world
and
>they are welcome. Just don't tell me there is no other way to build a
speaker.
>Let's not forget that only first order xo have a chance at passing a square
>wave, a criteria that has important subjective benefits, yet one that Mr.
Olson
>resolutely rejects on "objective" grounds in favor of higher order slopes.
>
>Mark
>
>
>
=========================================================================
From: Mark Donen <soledadd@worldnet.att.net>
Subject: Re: Bantying about opinion instead of listening and learning for ourselves
Date: Mon, 30 Nov 1998 13:14:20 -0500
Source: Sound Digest Archive v01.n510
Hi Doc,
I agree absolutely that we should choose on the basis of our experince which is
exactly what I did, and chose Tangos.
There are let's face it partisans on this list of manufacturers who disguise
their partisanship in supposedly objective language. Also some of these
partisans on this list manufacture amplifiers for commerical sale using one
brand of transformer or another. So, I hardly think it is objective to say that
Tango or Tamura transformers are in need of redesign by Mr LeFevre who by all
accounts has only been making transformeres for a few years whereas the Japanse
brands have been at it for many decades!
While I may have suggested bandwidth is a starting point for comparison, I did
not suggest in any way that it was the end of the story. On the other hand you
point to bass response amongst other supposed criteria in which Magnaquest
transformers are supposed to exceed the capacities of the sorry Tango or
Tamuras. Surely in itself bass is not even a particularly important criterion? I
say HF extension, you say bass. I know what I choose and why.
My own opinion is that as a inbuilt crowd pleaser for audio illiterates, bass
response is a very successful selling point. But I suppose we are talking
American "taste" (?) here, so bass always has priority over everything else. If
you want bass buy a Sunfire sub, but then anyone too cheap to buy Japanese
trannies would hardly be ready to shell out a grand for a sub now would they?
Mark
=========================================================================
From: Mark Donen <soledadd@worldnet.att.net>
Subject: Re: Bantying about opinion instead of listening and learning for ourselves
Date: Mon, 30 Nov 1998 13:45:32 -0500
Source: Sound Digest Archive v01.n510
Dear Doc,
I also note with interest how Mr. Olson has changed his views on horn speakers
since a long series of posts about a year ago. Naturally, I think it is salutary
that he has changed his mind, awakening so to speak from his dogmatic slumber. I
recall how it was argued at great length why horns cannot work well, by any
objective measured criteria. Are we to believe that Messieurs Exemplar have
overcome these problems, or that Mr. Olson has heard some good horns. My
suspicion is that the measured problems Mr. Olson refers to persist and that
their horns just sound good. Bollocks to "objective" criteria!
You have to correlate data to taste and measure the right thing. I am sure Mr.
Olson Ariel's measure great, but since he's enamored of the BBC house sound I
guess they wouldn't disturb a Brit granny slumping slowly sideways in a
semiconscious stupor on her sofa listening to the Proms on Radio 3! There are
those who think Quad ESLs and LS3/5A are the greatest speakers in the world and
they are welcome. Just don't tell me there is no other way to build a speaker.
Let's not forget that only first order xo have a chance at passing a square
wave, a criteria that has important subjective benefits, yet one that Mr. Olson
resolutely rejects on "objective" grounds in favor of higher order slopes.
Mark
=========================================================================
From: "Lynn T. Olson" <lynno@teleport.com>
Subject: Re: Bantying about opinion instead of listening and learning for ourselves
Date: Mon, 30 Nov 1998 15:32:59 -0800
Source: Sound Digest Archive v01.n510
>Dear Doc,
>
>I also note with interest how Mr. Olson has changed his views on horn speakers
>since a long series of posts about a year ago. Naturally, I think it is
>salutary
>that he has changed his mind, awakening so to speak from his dogmatic
>slumber. I
>recall how it was argued at great length why horns cannot work well, by any
>objective measured criteria. Are we to believe that Messieurs Exemplar have
>overcome these problems, or that Mr. Olson has heard some good horns. My
>suspicion is that the measured problems Mr. Olson refers to persist and that
>their horns just sound good. Bollocks to "objective" criteria!
>
>You have to correlate data to taste and measure the right thing. I am sure Mr.
>Olson Ariel's measure great, but since he's enamored of the BBC house sound I
>guess they wouldn't disturb a Brit granny slumping slowly sideways in a
>semiconscious stupor on her sofa listening to the Proms on Radio 3! There are
>those who think Quad ESLs and LS3/5A are the greatest speakers in the
>world and
>they are welcome. Just don't tell me there is no other way to build a speaker.
>Let's not forget that only first order xo have a chance at passing a square
>wave, a criteria that has important subjective benefits, yet one that Mr.
>Olson
>resolutely rejects on "objective" grounds in favor of higher order slopes.
>
>Mark
Well, the tone of the above letter speaks for itself. No comment.
As for background, I started designing commercial speakers for Audionics
from 1974 to 1979, and designed the TLM-200, M-30B, M-32, M-33, T-52, and
LO-2. The last system was a linear-phase speaker akin to the Spica TC-50,
except designed a year earlier, and using the Audax 6.5" bextrene
cast-frame midbass, and the Audax 1.25" tweeter. It reproduced square waves
very nicely, and the response was flat from about 70Hz to 18kHz within a
+/- 2dB window. This, along with a matching Bessel-alignment subwoofer, was
the system I listened to from 1979 to 1992.
The Ariel was originally intended to get the triode guys to stop pestering
me, so I wrote the first article for Positive Feedback. It also gave me a
chance to wake up MLSSA from its slumber, and get into the field again. I
never planned on replacing the LO-2 with the Ariels ... after all, as far
measurements and bandwidth were concerned, there was no contest, especially
the linear-phase aspect. It was meant as a just-for-fun quick project.
That changed once I did all of the tedious fine-tuning with pink-noise,
music, measurements, etc etc. Suddenly the ugly-duckling prototype was the
speaker I wanted to hear, and the LO-2 got retired to the garage (where
they stay today).
After a while I got tired with all the people hassling me about free copies
of Positive Feedback so they could build the speaker. Others even wanted me
to fax them the plans ... overseas! That gets expensive real quick. So my
sweetie, Karna, taught me how to write a Web page in 1995. Another year
passed, and the sheer volume of e-mail got to be too much, so I started the
Ariel Builder's Club, so these folks could get in touch with each other and
not bother me as much. Have I made any money on the Ariel? Not a nickel. If
I finally get the cabinets in production, wonderful, until then the Ariel
only makes money for Scan-Speak, Vifa, Madisound and North Creek Music
Systems.
The Ariels are a long way from perfect ... I'm as aware as anyone of that
... but nobody makes a perfect speaker that I know of. All speakers without
exception are horribly colored and unnatural compared to the real thing.
It's really a matter of finding something that gives pleasure, and people's
tastes are as different in speakers as they are in food preferences or
finding a mate.
>Just don't tell me there is no other way to build a speaker.
That's news to me. Has anyone in the Joelist ever made that claim at any time?
Lynn Olson
Editor, Valve & Tube News
E-mail: lynno@teleport.com
Ariel Speaker Page: http://www.teleport.com/~lynno/Ariel.htm
=========================================================================
From: "Fred Volz" <fcv@emotiveaudio.com>
Subject: Re: Bantying about opinion instead of listening and learning for ourselves
Date: Mon, 30 Nov 1998 23:15:22 -0500
Source: Sound Digest Archive v01.n511
- -----Original Message-----
From: Doc B. <bottlehead@silverlink.net>
Cc: sound@deliverator.io.com <sound@deliverator.io.com>
Date: Monday, November 30, 1998 12:54 PM
Subject: Bantying about opinion instead of listening and learning for
ourselves
>And as always, I suggest that using your own ears is the only true way to
>determine what works for you.
>
>Doc B.
>
I concur. I use my ears and they tell me that Mike's push-pull outputs are
transparent and have great bass. There are probably other fine transformers
out there, but, over and over, many of the very best sounding amps seem to
use his iron (my opinion). So, yeah, I care about specs and quality of
design. But, within a certain range of construction quality and price,
choosing an output transformer based on anything other than sound quality
would seem, to me at least, to represent misguided logic.
Fred Volz
=========================================================================
From: "Fred Volz" <fcv@emotiveaudio.com>
Subject: Re: Bantying about opinion instead of listening and learning for ourselves
Date: Tue, 1 Dec 1998 00:55:06 -0500
Source: Sound Digest Archive v01.n511
- -----Original Message-----
From: Mark Donen <soledadd@worldnet.att.net>
To: Doc B. <bottlehead@silverlink.net>
Cc: sound@deliverator.io.com <sound@deliverator.io.com>
Date: Monday, November 30, 1998 1:38 PM
Subject: Re: Bantying about opinion instead of listening and learning for
ourselves
>There are let's face it partisans on this list of manufacturers who
disguise
>their partisanship in supposedly objective language. Also some of these
>partisans on this list manufacture amplifiers for commerical sale using one
>brand of transformer or another.
The choice of which output transformer to use is but one of the hard choices
manufacturers must face. But, your assertion that this precludes
manufacturers (at least the ones on this list) from commenting on other
brands in an objective manner is without merit. I have used Mike's
transformers before and I like them very much. I am not alone. My choice was
based on sound quality. As a manufacturer, should my observations be
discounted because I wish to make a profit selling a product that is the
physical manifestation of my collected observations? Are all brands other
than Tango or Tamura lacking in merit?
Mr LeFevre who by all
>accounts has only been making transformeres for a few years whereas the
Japanse
>brands have been at it for many decades!
First off, Mike may have more experience than you are giving him credit for.
And with all do respect to the above mentioned brands, your logic here
cannot be supported. If years of experience necessarily relates to superior
products, explain why so many of the best sounding audio products are being
made by the youngest companies. This list is a veritable who's who of the
finest designers in the industry--or for that matter, NOT in the industry.
And, many of them are younger than the tubes they use in their designs.
On the other hand you
>point to bass response amongst other supposed criteria in which Magnaquest
>transformers are supposed to exceed the capacities of the sorry Tango or
>Tamuras. Surely in itself bass is not even a particularly important
criterion? I
>say HF extension, you say bass. I know what I choose and why.
>
>My own opinion is that as a inbuilt crowd pleaser for audio illiterates,
bass
>response is a very successful selling point. But I suppose we are talking
>American "taste" (?) here, so bass always has priority over everything
else. If
>you want bass buy a Sunfire sub, but then anyone too cheap to buy Japanese
>trannies would hardly be ready to shell out a grand for a sub now would
they?
>
>Mark
>
Yikes! Where does one begin? You seem to be arguing for your particular
taste rather than some point of quality. Regarding your views on Americans
and bass, you just plain sound angry. I'll admit that I like a system that
can reproduce clean pitch-accurate bass. Perhaps this is a weakness on my
part. But, it seems like something else is bothering you. Why not share with
the group?
By the way, the two amps I am working on now will probably use supped up
Hammond's. Believe it or not, there are actually some people in the world
that don't build there own stuff and are also on a budget. And, guess what?
They like music too.
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: Bantying about opinion instead of listening and learning for ourselves
Date: Tue, 01 Dec 1998 08:40:42 GMT
Source: Sound Digest Archive v01.n511
On Tue, 1 Dec 1998 00:55:06 -0500, "Fred Volz" <fcv@emotiveaudio.com>
wrote:
>By the way, the two amps I am working on now will probably use supped up
>Hammond's.
What does this mean in English?
- --dnb
=========================================================================
From: "Fred Volz" <fcv@emotiveaudio.com>
Subject: Re: Bantying about opinion instead of listening and learning for ourselves
Date: Tue, 1 Dec 1998 09:08:17 -0500
Source: Sound Digest Archive v01.n511
- -----Original Message-----
From: David Barnett <davidbarnett@aristotle.net>
To: sound@lists.io.com <sound@lists.io.com>
Date: Tuesday, December 01, 1998 4:25 AM
Subject: Re: Bantying about opinion instead of listening and learning for
ourselves
>On Tue, 1 Dec 1998 00:55:06 -0500, "Fred Volz" <fcv@emotiveaudio.com>
>wrote:
>
>>By the way, the two amps I am working on now will probably use supped up
>>Hammond's.
>
>What does this mean in English?
>
>--dnb
Err... I should have said "souped-up" Hammond. While some might suggest that
poor spelling is another American trait, I would guess that it's just me.
By souped-up, I mean that we will take a standard Hammond transformer and
have it manufactured using higher quality laminations and lead wires.
=========================================================================
From: Rick Francis <rfranci@uoft03.utoledo.edu>
Subject: Barbour's "Spectrum" (IEEE journal) tube article URL
Date: Fri, 04 Sep 1998 12:31:35 -0400 (EDT)
Source: Sound Digest Archive v01.n412
This is "The Cool Sound of Tubes", mentioned a few times here. Now you
can read it yourself without getting out of your chair:
http://www.spectrum.ieee.org/select/0898/tube.html
Sorry if someone already posted this.
Rick Francis, rfranci@uoft03.utoledo.edu
=========================================================================
From: tronan@orion.it.luc.edu (Thomas Ronan)
Subject: Bargain scope, anyone?
Date: Fri, 8 May 1998 14:48:29 -0500
Source: Sound Digest Archive v01.n273
Does anyone happen to have a little dual trace solid state 10-15MHz scope
lying around they'd part with for around $50 or so? Something that doesn't
weigh more than me, in other words.
I just missed out on one on the internet, for $25. It would have been
perfect, was dual trace and came with probes.
Oh well.
Thanks,
Tom
- ------
Thomas Ronan tronan@orion.it.luc.edu
1045 W. Montana, Chicago, IL 60614 773.528.0882
Lowther-America, Chicago Representative
=========================================================================
From: "Nilson, Bruce" <NilsonBruce@FCB.COM>
Subject: Bart: Hexfreds
Date: Mon, 29 Sep 1997 15:20:00 -0400
Source: Sound Digest Archive v01.n047
Bart,
Up until two months ago I was using 6DW4 tv damper diodes for
rectification.
The filaments were voltage and current regulated (try this on your IDHT
for a
quieter sound). They sounded better than a list of the usual rectifiers.
Then I tried hexfreds. Much better sound. The amp sounds less like a
tube
amp, more neutral and musical sounding simply because more music comes
through. Sort of like my VV52B output tube. More music, less crap in the
way
of the sound.
Bruce Nilson
=========================================================================
From: Guido Tent <gtent@ehv.sc.philips.com>
Subject: Re: Bart: Hexfreds
Date: Tue, 30 Sep 1997 09:31:49 +0200
Source: Sound Digest Archive v01.n048
At 15:20 29-09-97 -0400, Nilson, Bruce wrote:
>Bart,
>
>Up until two months ago I was using 6DW4 tv damper diodes for
>rectification.
>The filaments were voltage and current regulated (try this on your IDHT
>for a quieter sound).
Bruce,
I am always happy with better sound, but I do not understand "voltage and
current regulated". Either you put a voltage across the heater, and a
current starts flowing, or you force a current through the heater, and a
voltage arises
>They sounded better than a list of the usual rectifiers.
>
>Then I tried hexfreds. Much better sound. The amp sounds less like a
>tube amp, more neutral and musical sounding simply because more music comes
>through. Sort of like my VV52B output tube. More music, less crap in the way
>of the sound.
I think that is what I call "less mechanical"
Can you describe the type of diode ? Is it Schttky barrier, or what ? Can
you give a type number ? I would be happy to know, in order to understand
more of what is going on. I use SB 350 SB diodes, not bad to my experience.
Guido
>Bruce Nilson
>
>
" 640K ought to be enough for anybody" , Bill Gates, 1981
Disclaimer: The opinions expressed herin are my personal ones and do not in
any way reflect opinions or policies of my employer.
Guido Tent
Engineer Electro Magnetic Compatibility
Philips Semiconductors Systems Laboratory Eindhoven (PS-SLE)
Building BE303, (Hurksestraat 19)
P.O.Box 218, 5600MD Eindhoven, The Netherlands
Phone: +31-40-27 24553
fax : +31-40-27 22764
- - Let's make things better ! -
E-mail: guido.tent@ehv. sc.philips.com
Seri : gtent@nlsce1
=========================================================================
From: "Nilson, Bruce" <NilsonBruce@FCB.COM>
Subject: Re: Bart: Hexfreds
Date: Tue, 30 Sep 1997 11:02:00 -0400
Source: Sound Digest Archive v01.n049
Bart,
I use 2 with a CT trannie. I got 'em from Michael Percy 415 669 7181.
Can't
remember the exact International Rectifier specs, something like 1200v @
8A.
I've heard from some more knowledgable than I that Schottky aren't as
good.
Low voltage, 200v, Gallium Aresinide(?) rectifiers from Motorola are the
best, for now. I'd love to try these in a DHT filament for lower noise.
In my earlier post saying the filaments were "current regulated" was
incorrect, this should have been a constant current source.
Doc,
I just direct coupled my VV52B to a 7119 (you'll never get these back
from me
Dave!). Definitely the way to go. It lacks a little gain, and sounds
sooo
clear. And I thought teflon coupling caps sounded good!
I'll be doing active loading again in the next few thanks to Johnny C.
But first I'll try a few of the tricks on an active low pass filter I'm
building.
Bruce Nilson
=========================================================================
From: ROBERT ROSENTHAL <RBTR@mail.rkd.snds.com>
Subject: Bart: Hexfreds -Reply
Date: Mon, 29 Sep 1997 17:20:59 -0500
Source: Sound Digest Archive v01.n048
I've used hexfreds w/good success in a coupla amps,
too!
Robert RBTR@SNDS.COM
=========================================================================
From: dslagle@earthlink.net (Dave Slagle)
Subject: ?BAsis is AB?
Date: Fri, 23 Oct 1998 20:18:28 -0700 (PDT)
Source: Sound Digest Archive v01.n466
sorry for the palindrome title and renaming of a topic...but it does sorta
make sense doesn't it???
please note 3 lines of quoted text... the rest thought...
>>The fact that you didn't like a pair of Ariels (which I've heard and
>>liked)
>>makes me think that we have significantly different listening biases.
wrong!
you had significantly different listening situations... now if we broke out
those blindfolds.. oh sorry wrong fourum...
as lynn pointed out... there is sooo much that effects the sound we get
from any system... basing your opinions on only one sample (or mis-sample)
seems idiotic.
a system with synergy is what we are about... and any sort of show has to
have compromise...
krell amps are etched... pair them with dull speakers... viola
lowthers are bright... use a dull amp and again you have balance.
none of us will object to a balanced system... as long as the music comes
though... its that last step of improving on a balanced system where
opinions com into play... this is our downfall... we go beyond the music
and look for something better... speaking for myself this has taken me in
one direction based on certain factors... but I have learned... and can
then use that info to assist me in the future...
gettng back to a show or an audio salon... you don't have a chance... I am
barely into my journey... and still learning what I like... to expect
someone to pachwork together a system with your dream speaker at a show an
have you like it...seems like a pipe dream...(with a 2A3)
there is a huge assumption that the person setting up the system wants what
you want, and if they don't you blame the equipment...
BLAME THE PERSON... and for us thats easy... just look in the mirror.
give me your favorite pair of speakers an I will build an amp that will
make them sound awful... yet that same amp... oops system in front of the
those pesky transducers... will make my lowthers sing...
who is right??? who is wrong???
YOU ARE
=========================================================================
From: "Thom Mackris" <tmackris@earthlink.net>
Subject: Re: ?BAsis is AB?
Date: Mon, 26 Oct 1998 00:57:22 -0700
Source: Sound Digest Archive v01.n468
Hi Dave,
I thought my Lowther/VSAC post was stretching the bandwidth envelope as
it was and I didn't want to get into the area you covered in your post.
In general, I agree with your comments, but the point I was trying to
make was that Eric heard 2 different Lowther based systems and one Ariel
based system. He put all three of them in the same general sonic
universe (muffled sound). I think the smart money would say that we
have different taste. Having heard privately about VSAC from a couple
of individuals over the last couple of months, I suspect that the
Lowthers were set up well enough (and with a competent signal chain) to
let their basic character come through. Optimum? Probably not, but
enough to reveal their basic nature.
Ron W. made some interesting observations about why this might have been
the case, as did you and Lynn. Lynn described the Ariel setup and the
effects that close proximity to a wall had on the Ariels' bass response.
Having the disadvantage of not having been there, I had to extrapolate
from three different setups in unknown rooms with unknown signal paths.
One intent of my post (as I stated early on) was to better understand
Eric's biases for future reference. If ever I need his opinion on
something, I can factor in his sonic universe and make better use of the
information he gives me.
Oh well, I think I've beaten this dead horse sufficiently, although I
will pass along Tony Glynn's thoughts on the matter when/if he gets back
to me.
Regards,
Thom
>------------------------------
>
>Date: Fri, 23 Oct 1998 20:18:28 -0700 (PDT)
>From: dslagle@earthlink.net (Dave Slagle)
>Subject: ?BAsis is AB?
>
>sorry for the palindrome title and renaming of a topic...but it does
sorta
>make sense doesn't it???
>
>please note 3 lines of quoted text... the rest thought...
>
Thom said ...
>>>The fact that you didn't like a pair of Ariels (which I've heard and
>>>liked)
>>>makes me think that we have significantly different listening biases.
Dave said .....
>wrong!
>
>you had significantly different listening situations... now if we broke
out
>those blindfolds.. oh sorry wrong fourum...
>
>as lynn pointed out... there is sooo much that effects the sound we get
>from any system... basing your opinions on only one sample (or
mis-sample)
>seems idiotic.
>
>a system with synergy is what we are about... and any sort of show has
to
>have compromise...
>
>krell amps are etched... pair them with dull speakers... viola
<< BIG SNIP >>
=========================================================================
From: "william gaw." <whg@tiac.net>
Subject: bass horn
Date: Mon, 13 Oct 1997 09:50:12 -0400
Source: Sound Digest Archive v01.n066
Has anyone had a chance to hear Bruce Edgar's new bass horn? It's about 6
ft tall, looks like the monolith but goes down to about 30 hz. Bill G.
=========================================================================
From: "Bottlehead" <Bottlehead@prodigy.net>
Subject: Re: Basshorn design
Date: Tue, 30 Dec 1997 09:43:50 -0800
Source: Sound Digest Archive v01.n147
> Vas 76 dm3
>
Yeow! Could somebody convert that to teaspoons for me, so I can use it in
the new Lowther Cookbook CD rom I got for Xmas?
Doc B.
=========================================================================
From: "Bastien Bouchard" <bastienb@microtec.net>
Subject: Re: Basshorn design
Date: Tue, 30 Dec 1997 11:20:57 -0500
Source: Sound Digest Archive v01.n147
> Anybody knows what they should be for a Lowther PM6A? I can't seem to
find
> it anywhere, not even in the enclosed literature or Lowther's web site.
David,
From Hormal mag (sorry, no data for the PM6A):
PM6C PM2A
RDC: 6,78 ohm 6,93 ohm
fs: 41 Hz 39,8 Hz
Vas: 88,68 L 107,46 L
Qt: 0,24 0,15
Qe: 0,29 0,18
Qm: 1,28 0,83
Spl: 95 dB 97,7 dB
SD: 206 qcm 206 qcm
Le: 0,35 mH 0,16 mH
BL: 7,77 Tm 9,32 Tm
Cms: 1,49 mm/N 1,80 mm/N
BTW, don't expect serious data from Lowther themself...
Bastien
=========================================================================
From: Bert Doppenberg <lowther@wxs.nl>
Subject: Re: Basshorn design
Date: Tue, 30 Dec 1997 17:07:09 +0000
Source: Sound Digest Archive v01.n147
Hell David,
> I'm thinking of building a corner basshorn using the formulae as supplied
> by Bert Doppenberg. In his web page, the formula calls for knowing the
> driver's Fs, Qts and Vas.
> Anybody knows what they should be for a Lowther PM6A? I can't seem to find
> it anywhere, not even in the enclosed literature or Lowther's web site.
According to Klang und Ton:
Fs 45Hz (depending on temperature and age!)
Qts 0.22
Vas 76 dm3
> I'm picking up on Bert's idea of building it vertically along the corner of
> the room. Does it matter if the mouth is pointing up, down or towards you?
> I should think that if the crossover point is low enough (say 80hz or
> below), it wouldn't matter. Any opinion on this?
When you are planning to use ONLY the PM6A then the crossover can't be
set at 80Hz, unless you mean that Fg - 80Hz. When the PM6A only should
be used in the range <80 Hz then it's possible (but beware of the
maximum cone movement!)
> Secondly, I'm still undecided whether to make this a compound horn with one
> driver ( which would make it harder to design/build having an acoustical
> X-over to consider) or go the way of 2 horns/ 2 drivers with either passive
> or active X-overs. Any suggestions would be greatly appreciated.
For frequency's < 150Hz it doesn't matter where the hornmouth ends.....
Higher frequencies should be pointed at your direction!
- --
Greetings,
Bert Doppenberg -> lowther@wxs.nl ->
http://home.wxs.nl/~lowther/home.htm
=========================================================================
From: "David Tan" <dtkky@singnet.com.sg>
Subject: Basshorn design
Date: Tue, 30 Dec 1997 22:45:48 -0700
Source: Sound Digest Archive v01.n147
Hi joenetters,
I'm thinking of building a corner basshorn using the formulae as supplied
by Bert Doppenberg. In his web page, the formula calls for knowing the
driver's Fs, Qts and Vas.
Anybody knows what they should be for a Lowther PM6A? I can't seem to find
it anywhere, not even in the enclosed literature or Lowther's web site.
I'm picking up on Bert's idea of building it vertically along the corner of
the room. Does it matter if the mouth is pointing up, down or towards you?
I should think that if the crossover point is low enough (say 80hz or
below), it wouldn't matter. Any opinion on this?
Secondly, I'm still undecided whether to make this a compound horn with one
driver ( which would make it harder to design/build having an acoustical
X-over to consider) or go the way of 2 horns/ 2 drivers with either passive
or active X-overs. Any suggestions would be greatly appreciated.
David Tan
dtkky@singnet.com.sg
=========================================================================
From: MHuber@t-online.de (Manfred Huber)
Subject: Re: Basshorn design
Date: Wed, 31 Dec 97 10:03:01 -0100
Source: Sound Digest Archive v01.n147
Doc,
>Yeow! Could somebody convert that to teaspoons for me
1dm (dezimeter) = 0.1 meter => 1dm^3 = 1 liter = 0.035311 ft^3
I guess you can do the conversion to teaspoons on your own now <g>
Regards
Manfred
- ------------------
Manfred Huber
MHuber@t-online.de
- ------------------
=========================================================================
From: Jeroen Euwe <jeroen.euwe@let.ruu.nl>
Subject: Basshorn length
Date: Tue, 09 Dec 1997 12:37:59 +0000
Source: Sound Digest Archive v01.n129
Hi all,
Lately I have been fooling around with some basshorn designs using
the Altec 416-8A. Any throat size between 0.5 and optimum turns out
to be less than 1/4 wavelength long using a Fco of 40-45Hz.
I really really really like the 416-8A, but it looks like it may not
be suitable for a basshorn.
Does anybody have any suggestions/advice?
TIA
Jeroen
Jeroen.Euwe@let.ruu.nl
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: Basshorn length
Date: Tue, 9 Dec 1997 15:06:38 +0100 (MET)
Source: Sound Digest Archive v01.n129
At 12:37 09/12/1997 +0000, Jeroen wrote:
>Lately I have been fooling around with some basshorn designs using
>the Altec 416-8A. Any throat size between 0.5 and optimum turns out
>to be less than 1/4 wavelength long using a Fco of 40-45Hz.
>I really really really like the 416-8A, but it looks like it may not
>be suitable for a basshorn.
>Does anybody have any suggestions/advice?
Put 4 x 416.8A in your basshorns!
Best regards,
Jean-Michel Le Cleac'h, Paris, France.
=========================================================================
From: Thomas Danley <tom@ppci.com>
Subject: Re: Basshorn length
Date: Tue, 09 Dec 1997 11:15:11 -0600
Source: Sound Digest Archive v01.n130
Jeroen Euwe wrote:
>
> Hi all,
> Lately I have been fooling around with some basshorn designs using
> the Altec 416-8A. Any throat size between 0.5 and optimum turns out
> to be less than 1/4 wavelength long using a Fco of 40-45Hz.
> I really really really like the 416-8A, but it looks like it may not
> be suitable for a basshorn.
> Does anybody have any suggestions/advice?
> TIA
> Jeroen
> Jeroen.Euwe@let.ruu.nl
Hi
The electroacoustic efficiency gain of a horn is only realized when a
horn is about 1/2 wl or longer, this is the region where the impedance
is raised by the acoustic loading produced by the horn. A horn can be
used to 1/4 wl as the system is then a damped 1/4 wl resonator and that
resonance can extend the bw down to that point with the magnitude of the
ripple governed by the mouth size. At the 1/4 wl resonant point the
impedance will be lowered nearly to Rdc by the loading and between the
1/4 and 1/2 wl points there is 90 degree phase shift reflecting the
change from a reactive to resistive load. Fundimentally a larger problem
exists and that is that voice coil drivers do not have enough moving
mass nor a strong enough motor to be good horn drivers at subwoofer
frequencies. This means that they will have a low compression ratio (the
difference between throat and mouth area). You may want to look at a
more powerfull driver as well, I have had good luck with the RCF
L15p200ak in mid bass applications having a low cutoff between 50 - 70
HZ, you could probably use it lower with less efficiency and output.
You may want to consider a compound loaded driver to increase both the
motor strength and mass, when you plug those numbers into the design
formula's you will see it calls for both a smaller throat area and
produces a higher acoustic output. The problem with this though is often
one can't get the front volume small enough.
Don't worry about throat distortion either, the nonlinearity of air is
not a problem until the throat pressure is over about 155 dB, one bass
horn system I designed (Bass Tech 7) can produce 200 acoustic watts from
30 to 125 HZ with less than 2% distortion. It has a cone area of 266 sq
ins and a throat area of 78 sq/ins so the compression rato is 3.4:1.
A good design paper on low frequency horns and driver relationships can
be found in the Audio Engineering Society's Loudspeaker anthology #2
Called "On the specification of moving coil drivers for low frequency
horn loaded loudspeakers by Marshall Leach. A later addition was the
calculation for an appropriate hyperbolic flare which improves the
response near the low cutoff and increases the length for a given throat
and mouth area.
I have designed and built a number of commercial (Pro-Sound) mid bass
and bass subwoofers using most of the formula's in that paper (the
Intersonics TPL-1,2,3, MB-1, the SDL-4,5 and Bass Tech 7) most of which
use a low inertia servo-motor driver instead of a voice coil driver and
the last 2 go down to 30 HZ, all of which came out very close to the
predicted efficiency. You may wish to get a copy of several of the AES
papers dealing with predicting the output of horns that have smaller
than optimum mouth areas. You can get more info on the Bass Tech 7 from
the Servo-Drive corp, 847-724-5500 and the servo-motor drivers from
Contra Corner at http://www.mindspring.com/~sdinc/pages/contra.html
Have fun and deep bass.
Thomas Danley
Intersonics Technology Corp
=========================================================================
From: Bert Doppenberg <lowther@wxs.nl>
Subject: Re: Basshorn length
Date: Tue, 09 Dec 1997 19:09:01 +0000
Source: Sound Digest Archive v01.n130
Jeroen Euwe wrote:
>
> Hi all,
> Lately I have been fooling around with some basshorn designs using
> the Altec 416-8A. Any throat size between 0.5 and optimum turns out
> to be less than 1/4 wavelength long using a Fco of 40-45Hz.
> I really really really like the 416-8A, but it looks like it may not
> be suitable for a basshorn.
> Does anybody have any suggestions/advice?
> TIA
> Jeroen
> Jeroen.Euwe@let.ruu.nl
In the early days I have built a horn with a fc of 27Hz with two tiny 4"
units. They still play the lower frequencies very nicely. Why not making
the throat 0.3 Sd? For frequencies up to 150Hz, every (8") unit is
capable to do the trick (taking the quality of the unit in mind....).
What type of horn do you want to calculate? Tractrix, hyperbolic,
exponential.........?
- --
Greetings,
Bert Doppenberg -> lowther@wxs.nl ->
http://home.wxs.nl/~lowther/home.htm
=========================================================================
From: "Mark K. Long" <long@robby.caltech.edu>
Subject: Re: Basshorn length
Date: Wed, 10 Dec 1997 18:11:22 -0800
Source: Sound Digest Archive v01.n131
All right guys, there is some momentum here, let's get some candidate
designs going.....
Thomas Danley <tom@ppci.com> wrote:
> The electroacoustic efficiency gain of a horn is only realized when a
> horn is about 1/2 wl or longer, this is the region where the impedance
> is raised by the acoustic loading produced by the horn. A horn can be
> used to 1/4 wl as the system is then a damped 1/4 wl resonator and that
> resonance can extend the bw down to that point with the magnitude of the
> ripple governed by the mouth size. At the 1/4 wl resonant point the
> impedance will be lowered nearly to Rdc by the loading and between the
> 1/4 and 1/2 wl points there is 90 degree phase shift reflecting the
> change from a reactive to resistive load. Fundimentally a larger problem
Tom and guys, this is great stuff, thanks!! I've been struggling for
the last couple months with various comprimises for low frequency
enclosure design. I can handle the mid horn down to 200 hz (, but
below that's when the trouble starts. I'd love to have the dedicated
space that Bert has (http://home.wxs.nl/~lowther/oris1.jpg
http://home.wxs.nl/~lowther/concreet.jpg ), someday maybe.
My original irrational exuberance with regard to physical size has got
a hefty reality slap. Now I'm considering dipoles. and little down
firing cubes.....help!
As others have suggested, it seems that the only practical solution is
some sort of corner horn, such that the room is an extension of the
horn to provide the length needed to get to 1/2 wavelength. The
problem is that the folded corner horns are damn complicated to build.
What I'm trying to understand is the continuum between the infinite
baffle and a horn so that I can devise a more intelligent comprimise
for a reasonable sized room. At one end of the spectrum is a speaker
in a wall where the the horn is 180 degrees, or a speaker in a sealed
pyramid in the corner (speaker in bottom, point of pyramid into
corner, speaker facing out), so the only "horn" is the 3 walls in the
room (less than 1:1 compression ratio, probably 1:0.5 ). Is there
some intermediate solution that provides some benefits of horn
loading, but is more manageble than folded horns, or whole wall/floor
devices?
The audio technik kit (http://www.goodnet.com/~audiotk/subwoof.html)
maybe one option. the web page is short on details, but it appears
that the smaller system (ATS) has only one fold where the sound hits
the room corner. They don't provide any response numbers but it seems
that the driver requires a relatively small backchamber to make the
overall size reasonable. The new Audio Physic Terra? subwoofer shows a
vague resemblance, uses 2 8's? firing into the corner in a triangular
box, no compression throat though. Haven't heard it, big $$$.
Tom, I'm not familiar with the "Intersonics TPL-1,2,3, MB-1, the
SDL-4,5". Would appreciate any ideas for designs for 20-300hz horns
for in room use. I guess 30-150 would be ok but that's a minimum,
otherwise the mid horn gets comprimised.. Is it even reasonable to
span that freq range with a single enclosure? or is it better to go
16-60 and 60-200? the trouble always comes down to the transition
between the usually flabby woofer with the clean mid-horn. this is
what users of horns and electrostats have been fighting for a long time.
Tom brings up a good point about the driver, that begs the question:
what is it about horns that we like so much? (in terms of performance
numbers, and I'm not talking efficiency). Perhaps if we focus on that
target, we may have a chance of making some headway.
Thanks for any ideas!
Mark
long@caltech.edu
=========================================================================
From: Thomas Danley <tom@ppci.com>
Subject: Re: Basshorn length
Date: Wed, 10 Dec 1997 22:15:42 -0600
Source: Sound Digest Archive v01.n131
Mark K. Long wrote:
>
big snip>
>
> Tom brings up a good point about the driver, that begs the question:
> what is it about horns that we like so much? (in terms of performance
> numbers, and I'm not talking efficiency). Perhaps if we focus on that
> target, we may have a chance of making some headway.
>
> Thanks for any ideas!
>
Yes, for one, efficient horns have a different phase response than
direct radiators, they are nominally at zero degrees because of there
resistive loading. Direct radiators at low frequencies are generally
point sources IE: the diameter of the piston is a small fraction of a
wavelength in size and as a result in order to have flat response must
operate as a constant acceleration device. The result of this is that
the phase response (above resonance) is nominally -90 deg (in theory)
which means that it is incapable of reproducing an acoustic replica of a
complex electrical input signal. Put a square wave in and you don't get
anything like a square wave out because the different frequency
components are mis-aligned in phase and don't reassemble into a square
wave (not to say that at a particular frequency one couldn't find a
location where it does look like a square wave though nor to pass
judgement on the importance of this to ones ears).
It's just that, like an electrostatic speaker, an efficient horn can do
this and it may sound more realistic to ones ears. One of the best mid
speakers I ever measured with the TEF machine was a JBL375 on a big
slant plate lense horn, in the operating band it was very good in every
respect.
For low bass (16HZ to 80hz) you might want to look at the contra bass
which at 16 HZ has 40X the acoustic power of an 18" Velo and is only a
little bigger. It has 2, 15" driven (by a motor) cones and 2, 18"
passive radiators in an 7 cu/ft box. The guy (an old friend) that owns
Servo Drive now is offering a DIY kit.
http://www.mindspring.com/~sdinc/pages/contra.html
Best Regards,
Thomas Danley
Intersonics Technology Corp.
=========================================================================
From: peterca@ento.csiro.au
Subject: Re: Basshorn length
Date: Thu, 11 Dec 97 14:42:42 EST
Source: Sound Digest Archive v01.n131
>Tom and guys, this is great stuff, thanks!! I've been struggling for
>the last couple months with various comprimises for low frequency
>enclosure design. I can handle the mid horn down to 200 hz........
..........
>What I'm trying to understand is the continuum between the infinite
>baffle and a horn so that I can devise a more intelligent comprimise
>for a reasonable sized room. At one end of the spectrum is a speaker
>in a wall where the the horn is 180 degrees, or a speaker in a sealed
>pyramid in the corner (speaker in bottom, point of pyramid into
>corner, speaker facing out), so the only "horn" is the 3 walls in the
>room........
...............
>Thanks for any ideas!
>
>Mark
>long@caltech.edu
My reaction is that perhaps the solution is to abandon a horn for
sub-200Hz. If you feel competent to make >200Hz horns then perhaps a
direct radiator radiating into 1/8 space (the corner) can have matching
efficiency in the range up to 200Hz due to the 9db corner boost. At 200Hz
half a wavelength is just over 2.5 foot so a driver close to the floor in a
triangular footprint box mounted across the corner should remain loaded
throughout that sub-200Hz range. A corner mounting box can have a much
bigger internal volume than one out in the room without seeming to hog too
much real estate. The corner-fitting sealed or reflex box should provide a
handy top to put the mid-range horn on.
Dr. Peter Campbell (peterca@ento.csiro.au)
Div. Entomology, C.S.I.R.O. Ph.61-2-62464053 or -62464158 (w)
Box 1700 Canberra A.C.T. 2601 61-2-62516213 (h)
Australia 61-2-62464173 (fax)
=========================================================================
From: Bert Doppenberg <"Bert Doppenberg<lowther"@wxs.nl>
Subject: Re: Basshorn length
Date: Fri, 12 Dec 1997 14:36:12 +0000
Source: Sound Digest Archive v01.n133
Hello Mark,
> As others have suggested, it seems that the only practical solution is
> some sort of corner horn, such that the room is an extension of the
> horn to provide the length needed to get to 1/2 wavelength. The
> problem is that the folded corner horns are damn complicated to build.
Why not building a straight horn? If you have two corners, one solution
could be building the horn from the seeling down to the floor with a
bend at the end.........
- --
Greetings,
Bert Doppenberg -> lowther@wxs.nl ->
http://home.wxs.nl/~lowther/home.htm
=========================================================================
From: "Ken Dangerfield" <bpyakd@mail.island.net>
Subject: Bass Horn Questions (long)
Date: Mon, 9 Nov 1998 15:19:33 -0800
Source: Sound Digest Archive v01.n485
In my (seemingly) never ending quest for a bass horn design that will
fit in my listening room, I have been modelling a design using some
CAD and horn calculation software that I have. The design is
inspired by/modelled loosely after the Altec and Exemplar compromise
of using a smaller horn and obtaining the extreme low end by porting
the cabinet that holds the horn. I'm using the T/S parameters of
some JBL 12 inch woofers that I have on hand.
I have a few questions that I hope someone can help with:
1. To improve the bass reflex part of the design, I would like to
use 2 drivers on each side, mounted on the same horn, a la Altec 211
(although my design is nowhere near the size of a 211 !). Using
formulae from Leach, Edgar, etc. I can calculate the theoretical
optimum area of the throat opening for each driver. But in
positioning 2 drivers on the throat end of the same horn, there is
some additional space required in addition to the actual throat
openings to each driver. You can see this by looking at a picture of
an Altec 211. What effect, if any, is this going to have on the
performance of the horn? If there is likely to be a noticeable,
detrimental effect, any suggestions on how to ameliorate it, given
the preference to use 2 drivers?
2. Because space is at a premium in my listening room, I designed
the ports to fire forward like Altec, rather than to the rear like
the Exemplar. My thinking is that this will make them slightly less
sensitive to proximity to the front and side walls of the room.
What, if any, other difference will it make to have them firing
forward?
3. On his midrange horns, Edgar found that the actual high end
cutoff of the horn was substantially higher than was predicted by the
theoretical mass rolloff of the driver. Is this likely also to be
true on a bass horn? Recall that Edgar's mid driver was rear
firing into free space, whereas mine are rear firing into a bass
reflex volume which is much greater than the theoretical rear
chamber volume of a pure horn. The calculated mass rolloff of each
of my drivers is about 175Hz, but I would like the horn to reach
300Hz if possible.
4. Any opinions on the optimum way to control the high end of
the range of frequencies passing through the ports without unduly
muffling and affecting the perceived speed of the bass? As I
understand it, Deflex et al. will help to control standing waves but
not the range of information exiting through the ports.
5. At these frequencies, does the shape of the ports make any
significant difference (square, round, rectangle)?
Any thoughts, opinions, insights would be greatly appreciated.
Regards,
Ken Dangerfield
=========================================================================
From: Robert Jorgensen <robert.jorgensen@advalvas.be>
Subject: Re: Bass Horn Questions (long)
Date: Tue, 10 Nov 1998 08:30:00 +0100
Source: Sound Digest Archive v01.n485
At 15:19 09/11/98 -0800, you wrote:
>In my (seemingly) never ending quest for a bass horn design that will
>fit in my listening room, I have been modelling a design using some
>CAD and horn calculation software that I have. The design is
>inspired by/modelled loosely after the Altec and Exemplar compromise
>of using a smaller horn and obtaining the extreme low end by porting
>the cabinet that holds the horn. I'm using the T/S parameters of
>some JBL 12 inch woofers that I have on hand.
>
>I have a few questions that I hope someone can help with:
>
>1. To improve the bass reflex part of the design, I would like to
>use 2 drivers on each side, mounted on the same horn, a la Altec 211
>(although my design is nowhere near the size of a 211 !). Using
>formulae from Leach, Edgar, etc. I can calculate the theoretical
>optimum area of the throat opening for each driver. But in
>positioning 2 drivers on the throat end of the same horn, there is
>some additional space required in addition to the actual throat
>openings to each driver. You can see this by looking at a picture of
>an Altec 211. What effect, if any, is this going to have on the
>performance of the horn? If there is likely to be a noticeable,
>detrimental effect, any suggestions on how to ameliorate it, given
>the preference to use 2 drivers?
>
>Any thoughts, opinions, insights would be greatly appreciated.
>
>Regards,
>Ken Dangerfield
>
Hi Ken,
Have you checked Bert Doppenburgs Construction. That looked pretty good.
I think there were pictures on Mathijs De Vries' home page. Perhaps they
will give you a link and some more concrete info.
Greetings from Brussels
Robert
=========================================================================
From: Thomas Danley <Tom@ppci.com>
Subject: Re: Bass Horn Questions (long)
Date: Tue, 10 Nov 1998 09:47:59 -0600
Source: Sound Digest Archive v01.n485
Ken Dangerfield wrote:
> In my (seemingly) never ending quest for a bass horn design that will
> fit in my listening room, I have been modelling a design using some
> CAD and horn calculation software that I have. The design is
> inspired by/modelled loosely after the Altec and Exemplar compromise
> of using a smaller horn and obtaining the extreme low end by porting
> the cabinet that holds the horn. I'm using the T/S parameters of
> some JBL 12 inch woofers that I have on hand.
>
> I have a few questions that I hope someone can help with:
>
> 1. To improve the bass reflex part of the design, I would like to
> use 2 drivers on each side, mounted on the same horn, a la Altec 211
> (although my design is nowhere near the size of a 211 !). Using
> formulae from Leach, Edgar, etc. I can calculate the theoretical
> optimum area of the throat opening for each driver. But in
> positioning 2 drivers on the throat end of the same horn, there is
> some additional space required in addition to the actual throat
> openings to each driver. You can see this by looking at a picture of
> an Altec 211. What effect, if any, is this going to have on the
> performance of the horn? If there is likely to be a noticeable,
> detrimental effect, any suggestions on how to ameliorate it, given
> the preference to use 2 drivers?
>
> 2. Because space is at a premium in my listening room, I designed
> the ports to fire forward like Altec, rather than to the rear like
> the Exemplar. My thinking is that this will make them slightly less
> sensitive to proximity to the front and side walls of the room.
> What, if any, other difference will it make to have them firing
> forward?
>
> 3. On his midrange horns, Edgar found that the actual high end
> cutoff of the horn was substantially higher than was predicted by the
> theoretical mass rolloff of the driver. Is this likely also to be
> true on a bass horn? Recall that Edgar's mid driver was rear
> firing into free space, whereas mine are rear firing into a bass
> reflex volume which is much greater than the theoretical rear
> chamber volume of a pure horn. The calculated mass rolloff of each
> of my drivers is about 175Hz, but I would like the horn to reach
> 300Hz if possible.
>
> 4. Any opinions on the optimum way to control the high end of
> the range of frequencies passing through the ports without unduly
> muffling and affecting the perceived speed of the bass? As I
> understand it, Deflex et al. will help to control standing waves but
> not the range of information exiting through the ports.
>
> 5. At these frequencies, does the shape of the ports make any
> significant difference (square, round, rectangle)?
>
> Any thoughts, opinions, insights would be greatly appreciated.
>
> Regards,
> Ken Dangerfield
HiI can certainly relate to the quest for the ultimate bass horn,
although the mixed radiator variety (horn and vented) systems cannot
achieve the same level of performance of a purpose built, proper bass
horn.
Unfortunately the "mixed" radiation systems must be "hand tuned" if there
is any hope of matching the horn and vent radiation. The first question
you need to ask is if you have enough space to actually have a real bass
horn? Like many other examples of horn lore, the size of the mouth does
not have to be prohibitive if you can put the horn mouth in a corner. The
horn's job is primarily to transform the impedance of the radiation into
the room to that of the driver (both the horn flare rate and compression
ratio are the transformer)
which reduces the radiator motion for a given acoustic power and
increases the radiation efficiency (proportional to the amount the
resistive portion of the impedance is raised. A %50 efficient horn will
then have a resistive impedance approximately 2X the drivers Rdc.
I have found, in practice that the mouth area can be reduced by half from
the "ideal" is and still get very nice results, including wall effects it
is even smaller.
For example a 25 HZ horn "ideally" needs a mouth about 14 feet in
diameter. (the normal free space model everyone uses)
In practice about half the area still gives good results = 9.9 feet in
diameter.
If placed on the ground, the area is cut in half again =7 feet in
diameter.
If against a wall and ground = 4.9 feet in diameter
And in a corner on the ground = 3.5 feet in diameter (37" square).
Unfortunately the horn must still be 1/4 wl or longer which means finding
the proper driver is difficult.
I have horn design computer programs which can :
1 design the optimum horn for a given driver and hi-lo cut off's.
2 design the optimum driver for a given horn & hi-lo freq.'s
3 calculate the frequency response given driver parameters and
dimensions of a "real world" horn, (front volume, rear volume, throat
area, mouth area, length, flare rate and "t").
If you would like, send me your T&S parameters and desired BW and I'll
punch out a horn design.
The programs are proprietary and I use them frequently in my work so I
can't send copies out but I would be happy to do a few models when I have
spare time.
Here is a bass horn that has been in production for 6 years designed with
the software although it is too much for in a house.
http://servodrive.com/pages/bt7_spec.shtml
Best Regards,
Tom Danley
ITC
=========================================================================
From: "Ken Dangerfield" <bpyakd@mail.island.net>
Subject: Re: Bass Horn Questions (long)
Date: Tue, 10 Nov 1998 17:44:56 -0800
Source: Sound Digest Archive v01.n486
Tom:
As usual, a very informative and helpful reply. Thank you.
You previously calculated a horn design for my drivers (JBL 128H)
but the horn was 14 feet long. I can easily accomodate the 1/4 size
mouth in a corner but I still haven't figured out how to fold the 14
feet into a manageable size without a lot of 180 degree turns (which
I understand are a definite no no in horns).
Also, with the bass horns limited to corner placement and expected to
function up to ~300Hz, I have some concerns about the ability to
position the mid horn and tweeter for optimum imaging while still
maintaining physical proximity to the bass horn.
Any further thoughts or suggestions greatly appreciated.
Regards and thank you
Ken Dangerfield
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: Bass Horn Questions (long)
Date: Tue, 10 Nov 1998 18:42:19 -0800
Source: Sound Digest Archive v01.n486
Ken Dangerfield wrote:
> ...snip...
> 3. On his midrange horns, Edgar found that the actual high end
> cutoff of the horn was substantially higher than was predicted by the
> theoretical mass rolloff of the driver. Is this likely also to be
> true on a bass horn? Recall that Edgar's mid driver was rear
> firing into free space, whereas mine are rear firing into a bass
> reflex volume which is much greater than the theoretical rear
> chamber volume of a pure horn. The calculated mass rolloff of each
> of my drivers is about 175Hz, but I would like the horn to reach
> 300Hz if possible. ...rest snipped...
I've said this here before, but one more time shoudn't hurt ... and
btw, I got this from Dr. Edgar's talk at VSAC'97, which I think was
pretty much his usual presentation. There are two effects that
increase level with frequency above the usual mass rolloff
calculation. First, with a plain exponential or tractrix profile, the
directivity increases with frequency so that while the total radiated
power is constant, the on-axis SPL increases at about 3dB per octave
in the passband. Above the mass rolloff, the on-axis SPL falls at 3dB
per octave and the power at 6dB per octave. Second, some drivers have
a rising frequency response due to carefully managed cone vibration
patterns. The Altec A-7 drivers and the JBL LE-5 midrange are
examples. I would expect that many of the lead-guitar type speakers do
also. If this rise is another 3 dB per octave, then the on-axis result
is flat above the mass rolloff frequency. Very convenient, and if done
right it can be very good sounding.
- -Paul Joppa
=========================================================================
From: "Bill Gaw" <whg@tiac.net>
Subject: Re: Bass Horn Questions (long)
Date: Wed, 11 Nov 1998 08:18:03 -0500
Source: Sound Digest Archive v01.n486
Tom:
What's the speaker in the middle ogf the specs page for Servo-Drive with the
question mark, and what are it's specs. Bill
- -----Original Message-----
From: Thomas Danley <Tom@ppci.com>
To: Ken Dangerfield <bpyakd@mail.island.net>
Cc: sound@deliverator.io.com <sound@deliverator.io.com>
Date: Tuesday, November 10, 1998 1:08 PM
Subject: Re: Bass Horn Questions (long)
>
>
>
=========================================================================
From: Thomas Danley <Tom@ppci.com>
Subject: Re: Bass Horn Questions (long)
Date: Wed, 11 Nov 1998 11:18:14 -0600
Source: Sound Digest Archive v01.n486
Bill Gaw wrote:
> Tom:
> What's the speaker in the middle ogf the specs page for Servo-Drive with the
> question mark, and what are it's specs. Bill
It was a more or less full range (150 - 18 kHz) line source (called a Focussed
Field) which was part of the product line from the company before Servo Drive.
It used a rotary motor and radiator and had no crossover or phase shift
(nominally zero degrees above 200 HZ, like a horn) As you may have noticed many
of my driver designs (like the Servo Drive, the full range driver and Phoenix
Cyclone) use rotary motion in the motor and in some cases the radiator also
instead of the normal "in and out" motion of piston drivers. Rotary systems
obey an entirely different set of physical rules which govern the distribution
of force and mass. While impractical with a normal driver, the Phoenix Cyclone
has a moving magnet motor on a substantial shaft but has in effect, little
moving mass, this is only possible because of the different rules, the weight of
the parts can be several pounds but acoustically be an ounce or less in driver
MMS. The different rules can also apply to acoustic radiation and so,(if done
properly) one can have a large radiating area without a narrow pencil beam
radiation pattern.
I urged Brad at Servo Drive not to continue that product and I am working on a
replacement for it
and thus cannot speak of it much further right now.
A similar, wider band Hi Fi prototype can be seen at Rudi Blondia's web site
(still looking) in the spring's bass BBQ pictures. That was also a line source,
the driver is 48" long and is flat (+-2) from about 65 to 24 kHz.
Best Regards,
Tom
ITC
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@roads.sa.gov.au>
Subject: RE: Bass Horn Questions (long)
Date: Wed, 11 Nov 1998 20:32:14 +1030
Source: Sound Digest Archive v01.n486
> -----Original Message-----
> From: Ken Dangerfield [mailto:bpyakd@mail.island.net]
>
> 2. Because space is at a premium in my listening room, I designed
> the ports to fire forward like Altec, rather than to the rear like
> the Exemplar. My thinking is that this will make them slightly less
> sensitive to proximity to the front and side walls of the room.
> What, if any, other difference will it make to have them firing
> forward?
I expect that the ports will have a much lower output efficiency than the
horn. So firing them back to a wall would provide valuable boost. OTOH, your
Exemplar-like horn is, I think, only very slightly horn-like, so the
efficiency mismatch will be nothing like as large as it would have been if
you built a fully developed horn on the front of the driver.
This is why you will probably get messages from others saying that much
trial and much error will be an essential part of getting this speaker to
work. And THAT is why I lost my initial enthusiasm to develop an
Exemplar-like speaker around my JBL 2220's.
>
> 3. On his midrange horns, Edgar found that the actual high end
> cut-off of the horn was substantially higher than was predicted by the
> theoretical mass rolloff of the driver. Is this likely also to be
> true on a bass horn? Recall that Edgar's mid driver was rear
> firing into free space, whereas mine are rear firing into a bass
> reflex volume which is much greater than the theoretical rear
> chamber volume of a pure horn. The calculated mass rolloff of each
> of my drivers is about 175Hz, but I would like the horn to reach
> 300Hz if possible.
On his bass horns, Edgar found that the actual high end cut-off of the horn
was substantially correct as predicted by the theoretical mass rolloff of
the driver.
The higher results for midrange horns only applied to designs where the
throat size equals the piston area, i.e. a large throat. Which is the case
for your bass 'horn'. I think your result will depend on whether your
drivers have a 6dB/octave rising radiation resistance between 175 Hz and
300 Hz. If so, maybe it will work out.
In other words, both the low-end coupling to the reflex ports, and the
high-end coupling to the 300 Hz midrange speaker, are going to be
suck-it-and-see propositions. I would see this concept design as a
high-risk, learning-by-doing exercise. Yep, I think it qualifies for true
Joenetter status. After looking into it, I decided not to travel this path.
But don't despair: Exemplar proves the potential of this approach, and if it
suits your temperament better than mine, I am sure it could be very
rewarding.
I will also add that Edgar found his eighth-space horn (corner horn) designs
only worked as predicted at the low end if they fired *into* the corner. It
took him some years to conclude that if the horn mouth was exiting forwards
into the room, you really need a quarter-space horn to avoid bass
disappointment. This is why his recent designs like the Edgar 50 2-way horn
use a quarter-space bass horn design. I think you need to consider a
quarter-space horn. (Sorry)
Grant
Grant Sellek
Adelaide, Australia
grant.sellek@roads.sa.gov.au
=========================================================================
From: Thomas Danley <Tom@ppci.com>
Subject: Re: Bass Horn Questions (painting in a corner)
Date: Wed, 11 Nov 1998 11:18:07 -0600
Source: Sound Digest Archive v01.n486
Ken Dangerfield wrote:
> Tom:
>
> As usual, a very informative and helpful reply. Thank you.
>
> You previously calculated a horn design for my drivers (JBL 128H)
> but the horn was 14 feet long. I can easily accomodate the 1/4 size
> mouth in a corner but I still haven't figured out how to fold the 14
> feet into a manageable size without a lot of 180 degree turns (which
> I understand are a definite no no in horns).
HiWell the length is a problem, it MUST be at least a quarter WL at the
low cutoff and best efficiency results when it is at least 1/2 WL at the
low cutoff.
Folds can be a problem acoustically and do deserve a place in book of
"horn lore".
The problem with folds is actually two problems which can appear similar
in effect.
Problem one is that when the path length difference between the inside
and outside of the bend equals 1 or more (odd number) half wavelengths,
there will be a notch in the response. When the path length difference
equals 1 wavelength or more (even number), there will be a peak in the
response.
Also, folding a horn poses a logistical question, how do you decide how
to fold the horn, an incorrect fold which represents a change in
acoustical impedance (by changing area in appropriately one way or the
other) which causes reflections and the corresponding dips and peaks in
the response. A rule of thumb I use is to think of the horn as being
full of sand or other incompressible fluid. The horn when bent, MUST
contain the same volume it did before being bent (typically people seem
to shorten the horn and reduce the volume due to the folds).
Bottom line, keep the path length differences in the bends to less than
1/4 wl at the highest frequency you will need to operate (bend the horn
where its small) and keep an eye on the volume at the folds. I generally
cut out a straight version of the horn on paper and snip it apart to fold
and keep the total area on the paper the same as when straight. .
>
>
> Also, with the bass horns limited to corner placement and expected to
> function up to ~300Hz, I have some concerns about the ability to
> position the mid horn and tweeter for optimum imaging while still
> maintaining physical proximity to the bass horn.
>
> Any further thoughts or suggestions greatly appreciated.
Corners are interesting acoustically and if used properly can actually
be part of the horn allowing a further reduction in mouth size.If you
were an ant in the corner looking out into the room, you would be at the
tip of a horn who's surface area increases at 1.57 X distance^2. One
would plot this curve out, find the point that the expansion is at a
similar rate to that of the desired lf corner and up to that point is all
of the horn you need construct.
The issue of time delay and matching the upper/lower horns is the one
problem stopping me from having a horn system currently. Certainly one
could use a digital delay and perhaps it might be transparent enough but
I can't afford to buy a decent one and the focus of my work is currently
a very wide band horn driver.
So far as what to do, it is a compromise best judged by your ears so if
you can, make things so that you can move them around before making it
permanent.
Good luck
Tom Danley
>
=========================================================================
From: "Ken Dangerfield" <bpyakd@mail.island.net>
Subject: Bass Horn - Thanks
Date: Wed, 11 Nov 1998 20:22:30 -0800
Source: Sound Digest Archive v01.n487
Many thanks to everyone who took the time to reply to my post. After
considering some of the issues revealed to me, I now see why it took
Tucker and Markwart umpteen iterations to get it right (and they
actually knew what they were doing).
However, I am not completely deterred - only temporarily perplexed
(which I find is not an uncommon state of mind for me lately).
Regards,
Ken Dangerfield
=========================================================================
From: "Doc B." <bottlehead@silverlink.net>
Subject: Re: Bass/lower-mid PP tube amp with 2A3's
Date: Sun, 24 May 1998 11:09:14 -0700
Source: Sound Digest Archive v01.n290
I sat down and wrote this long answer to Torbjorn, which basically said
that, as usual, I don't know if it will work, I am trying to get folks to
eXperiment, there may be benefits to PP parafeed we won't know bout until
somebody tries it, blah, blah, and talked about a very simple parafeed PP
arrangement, then I started thinking about the many possibilities involved
in wiring a PP parafeed-
At that point my feeble brain went on holiday, and I blew away the post, as
I started wrestling with this idea:
What if we use the PP trans as our plate choke? Hook it to each plate and
feed it B+ from the center as usual. Leave the secondary disconnected.
We now have a plate choke with super high inductance and balanced out DC,
right?
Now, what if we consider each output tube as an opposed SE amp, along the
lines of the eXperiment tried by Bascom King a while back, where he inverted
the phase of a signal into one amp of a matched pair of SE amps, and
paralleled the outputs of the two amps (back in phase), getting easily
measurable PP level output power and 2nd harmonic reduction without any
crossover distortion. Don't ask me the details, he describes how to make a
simple rig to flip the phase of the signal from his preamp to one amp in his
article in VALVE. The test results seem to indicate it works very well.
So, in this wierd new scheme we send out of phase signal to the input of one
driver/output tube, in phase to the other.
Now we cap couple a nickel parafeed SE OT with super high inductance to each
plate (or couple the OTs directly to the plates and put the caps between the
other end of the para OT and ground, which always sounds better), and
parallel the outputs, being careful to wire the outputs back in phase.
Do the out of phase signals get cancelled by the PP plate choke in this
scheme, and do I really need two plate chokes, e.g., do I need two isolated
plate chokes? Or would this fly? I keep stumping myself on this one.
Am I really full of shit here? Wouldn't be the first time, huh.
Help me, folks, it's probably obvious, but it's been a long month,
Doc B.
=========================================================================
From: "=?ISO-8859-1?Q?Torbj=F8rn_Lien?=" <mdrivekl@online.no>
Subject: Re: Bass/lower-mid PP tube amp with 2A3's
Date: Sun, 24 May 1998 17:08:31 +0200
Source: Sound Digest Archive v01.n290
Hello Doc, Grant and the rest of you:
Maybee I'm dumb, but I really don't understand this:
Doc wrote:
> Gut the sucker for its power trans and OT's. The OT's will probably
be 6-9K.
That's ok. Get it for the output iron,-
> Get some chokes, 30H minimum......... Find some cheap oil
> poly motor start caps, at least 4 mfd.
> Build a PP 2A3 parafeed.
> A bunch of people will say PP parafeed has no advantage,
>I say build it, find out that it probably sounds better -
>........I bet the parafeed gives great resolution.
So, If I've got it right, your suggesting this: The output
stage shall consist of 2 times the 2A3 pr. amp. These shall
be choke loaded.One choke pr. tube, 2 chokes in total pr. amp. Then you
are cap coupling the output AC to the cheapskated X-former by the means
of one (two?) capasitors.
Once upon a time the push-pull circuit were invented
because, amongst others it took care of the unbalanced DC
through the primary of the output x-former. You are suggesting to put
an unspecified 2.order high-pass filter in the signal chain of this
bass/mid amp,and to remove harmless balanced-out DC from the output
x-former.The inductance on output pp x-formers are usually several
hundred Hy's, loading chokes with unbalanced DC far less and in
paralell with the output x-formers, reducing it even further.Also, as
this is suggested to be a class"A" amplifier, the coupling between
primaries shouldn't be an issue ,-
So I wonder: What is the philosophy behind this?
> Drive those 2A3s with a simple direct coupled differential > circuit,
with active loads.
> The active loads should balance the drive stage like > nobody's
business.......
Here is again something I'd like to be educated in. In my
book the load resistances in a differential stage has to
be of a *finite* values, just to make it work as a reasonably
balanced phase splitter.Im thinking of active loads here to be constant
current sources in the anodes, but that won't work, so the loads you're
talking of has to be something else.Would you elaborate?
:TL
=========================================================================
From: "Lynn T. Olson" <lynno@teleport.com>
Subject: Re: Bass/lower-mid PP tube amp with 2A3's
Date: Mon, 25 May 1998 03:18:01 -0700
Source: Sound Digest Archive v01.n291
>What if we use the PP trans as our plate choke? Hook it to each plate and
>feed it B+ from the center as usual. Leave the secondary disconnected.
>We now have a plate choke with super high inductance and balanced out DC,
>right?
>
>Do the out of phase signals get cancelled by the PP plate choke in this
>scheme, and do I really need two plate chokes, e.g., do I need two isolated
>plate chokes? Or would this fly? I keep stumping myself on this one.
>Am I really full of shit here? Wouldn't be the first time, huh.
>
>Help me, folks, it's probably obvious, but it's been a long month,
>
>Doc B.
The CT choke (or PP OPT) do not behave like a pair of chokes tied to the PP
plates. The difference is the autoformer action of the CT iron, which is
not present in the paired but isolated chokes.
Here's a little thought-experiment:
A) CT choke or PP OPT, and parafeed OPT. Run one side of the circuit
normally, but shut off the heater or filament of the other power tube, so
we get a kind of half-assed SE amp. Lo and behold, when we swing the plate
of the working side 100 volts above normal, the plate of the shut-off tube
swings down 100 volts, despite the fact the tube is stone cold and off.
This is the autoformer action of the CT iron doing the swing in the
opposite direction. Indeed, way back when, some radios even used a CT choke
as a cheapo phase inverter.
As far as impedances are concerned, our 6K trans is only half-connected, so
it looks like the circuit has a 1.5K primary when only one tube is working.
B) Paired chokes, no CT connection, and a parafeed PP OPT. Run one side of
the circuit normally, but shut off the heater or filament of the other
power tube, so we get a different kind of half-assed SE amp. No autoformer
action is present, the plate of the "off" tube just sits there at B+, and
looks like an open circuit at audio frequencies.
Since our OPT, like any transformer, is only sensitive to *current flows*
across the primary, we get zero output from the secondary ... it's like
leaving the one end of the primary disconnected as far as the AC signal is
concerned.
Circuit (B) is equivalent to a mirrored pair of parafeed SE amps, while the
more conventional PP OPT is not, thanks to the autoformer action. This
makes a difference as far as clipping and onset of Class B operation is
concerned ... I'm not too sure the (B) circuit is even capable of Class B
operation, I think it would just start clipping, like a SE amp.
Just to twist your heads around a bit more, I once saw an article in some
obscure 1950's magazine that proposed putting a big audio choke directly in
series with the B+ connection of the PP OPT. This essentially forces the PP
tubes into Class A at all times, and removes the autoformer action of the
OPT by forcing the CT to a very high impedance, instead of the low
impedance of the normal CT connection (low because the CT is usually
connected to 100uF going right to ground as part of the PS filtering).
So we have *three* circuits of interest: conventional PP with CT to low AC
impedance, weird PP with CT going to a high AC impedance, and the full-kink
option of dual AF chokes, a single blocking cap for the OPT, and a PP OPT
running in parafeed. The blocking cap might even be optional, depending on
how much DC offset the OPT can tolerate, and whether the DC offset has an
easier path thru the OPT or the paired chokes. Fun math here for the geeks,
plus the whoopee option of nickel iron for PP fans like me.
Lynn T. Olson
E-mail: lynno@teleport.com
Ariel Speaker Page: http://www.teleport.com/~lynno/Ariel.htm
=========================================================================
From: Tim Reese <reese@nmr.MGH.harvard.EDU>
Subject: Re: Bass/lower-mid PP tube amp with 2A3's
Date: Mon, 25 May 1998 10:03:15 -0400 (EDT)
Source: Sound Digest Archive v01.n291
Lynn Olson wrote
>Just to twist your heads around a bit more, I once saw an article in some
>obscure 1950's magazine that proposed putting a big audio choke directly in
>series with the B+ connection of the PP OPT. This essentially forces the PP
>tubes into Class A at all times, and removes the autoformer action of the
>OPT by forcing the CT to a very high impedance, instead of the low
>impedance of the normal CT connection (low because the CT is usually
>connected to 100uF going right to ground as part of the PS filtering).
This came up more recently in a Glass Audio article from 1994, "The
Importance of Balance in Push-Pull Amplifiers" by Joeseph Marshall, V6 #4.
Marshall recommends 15-25H, a big choke indeed. regards tr
- ----------------------------------------------------------------------
Tim Reese, MGH NMR Center reese@nmr.MGH.harvard.edu
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: Re: Bass/lower-mid PP tube amp with 2A3's
Date: Mon, 25 May 1998 10:48:31 -0700
Source: Sound Digest Archive v01.n291
Hi All,
Wouldn't an unbypassed cathode resistor (assuming cathode bias)
accomplish essentially the same thing as an unbypassed choke in the B+,
or at least a very similar thing, i. e., more nearly force full class A
operation.
Dan Marshall
Tim Reese wrote:
>
> Lynn Olson wrote
>
> >Just to twist your heads around a bit more, I once saw an article in some
> >obscure 1950's magazine that proposed putting a big audio choke directly in
> >series with the B+ connection of the PP OPT. This essentially forces the PP
> >tubes into Class A at all times, and removes the autoformer action of the
> >OPT by forcing the CT to a very high impedance, instead of the low
> >impedance of the normal CT connection (low because the CT is usually
> >connected to 100uF going right to ground as part of the PS filtering).
>
> This came up more recently in a Glass Audio article from 1994, "The
> Importance of Balance in Push-Pull Amplifiers" by Joeseph Marshall, V6 #4.
> Marshall recommends 15-25H, a big choke indeed. regards tr
> ----------------------------------------------------------------------
> Tim Reese, MGH NMR Center reese@nmr.MGH.harvard.edu
=========================================================================
From: "=?ISO-8859-1?Q?Torbj=F8rn_Lien?=" <mdrivekl@online.no>
Subject: Re: Bass/lower-mid tube amp for Quality not Quantity?
Date: Sat, 23 May 1998 15:12:50 +0200
Source: Sound Digest Archive v01.n289
Hello Grant,-
I'm a bit puzzeled by your posting. IMHO there is no
hyper musical economic bass tube, although obviously a
2A3 might work better,or atleast easier in this regard
than ex. an 801A. (Or,- I've found the 6550 to be wastly superior to
any EL34...But that was on my ongoing quest to make a killer
bass-guitar rig!)
It's more like how you do it than *what* to use. Meaning you just have
to try to build an amp and get some knowledge out of it. Any amp, cause
the only one that might approve/ disapprove on it is yourselves. And
you learn a lot on the way. But, since bass and musicality is the issue
here, limit yourselves to class "A" PP with triodes.
Ģf economics is in the way of this approach, try devellop
it. I know I use a lot of money on this hobby but atleast
it don't feels that way. As I have develloped a dumpster-divin' tech.
and also have managed to get different sources for old parts. So I only
have to use money on output x-formers and tubes.
But ok,- here's my 2 cent for gettin a good, musical,
el-cheapo bass amp :
Find and buy/get/steal etc. a cheap integrated stereo/mono, anything
with "decent" sized iron and a pair o'EL84's or 6V6 will work.I
understand it's a lot of these 12-15 W amps around, that can be had for
little or nothing if you're lucky. Save the X-formers and throw the
rest away. Then, buy some 6BL7's,or 6BX7's and rebuild yourselves a
4-5W PP class "A" amp, using 2 of the BL/BX -types pr. output
paralelled..
Use your favorite voltage tubes upstream or some SL/SN7's.
That's all. If you collect the parts, and manage to get a weekend
entirely for yourselves thats all you need for making
a finished, or atleast working unit.(Huh,-I'm alone right now
myselves,-should know better than to vaste my time in front
of this screen! Better close off and ,-..)
:TL
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@roads.sa.gov.au>
Subject: Bass/lower-mid tube amp for Quality not Quantity?
Date: Sat, 23 May 1998 19:44:52 +0930
Source: Sound Digest Archive v01.n289
Dear all,
this is a semi-hypothetical, so feel free to make wild suggestions as
well as relate any practical experience. ;-)
For biamping a sensitive bass speaker, crossing over say 500-1000hz,
what options are there for a **fairly economical** DIY amp that has
really good sound quality (or potential)? Watts are not an issue. The
range this amp will handle includes a fair amount of vocal and
instrumental reproduction, so tonal balance and accuracy are important
(so please don't mistake it for a subwoofer amp which brings to mind
kick drums and bass guitars).
The treble would be handled by a small class A DHT. I don't know if this
is an important point.
I am half expecting a response that, if a bigger SE DHT is too pricey,
which it is (especially with an HV supply, or a $$$ airgapped
high-current OPT with strong bass performance), then all else is
gaslight. But is there any sort of hierarchy of preference below this,
or do we jump straight to Class B 6550's? (I doubt).
So with sound quality in mind, maybe we can start with a tube that
sounds good in the bass and lower mid and is quite readily available
(new or NOS). Suggestions? I don't want to lead discussion here, lacking
any experience, but maybe the options include:
a) DHT like Chinese 2A3, or the Svetlana SV811-3 or 811-10 (Bob D? - and
I am aware that some don't much like this tube's treble, but we are not
talking treble), or...... what else?
b) Triode-wired or screen-driven pentodes, like (right out of my depth)
maybe EL34, EL509, EL84.....?
c) Straight pentode operated tube candidates, maybe 6550, 807, 5881,
6V6, 6L6 (hey, jc picked 'em for his latest SP article!), the sky's the
limit, but I don't know what has good lower mids, (I don't know anything
actually).
Then there is the choice of topologies: SE, para-SE, Class A PP, Class B
PP. Now, we are talking bass and lower mids. And affordable tonal
accuracy that invites listeners into the music. Maybe the generalities
that we hear about full-range amps (many like SE, everyone likes Class
A, nobody wants parallel tubes or feedback) need to be changed for this
limited-bandwidth amp? For a "different" example, I once saw a 16W PP
amp with class B 46 output tubes driven by a class A 46 into a step-down
IT. Hmm, low-mu driver, high-mu output tube, DHT's (albeit double-grid),
no NFB. Interesting combination of desirable and suspect features. Maybe
a good-sounding tube, but can we live with class B in the low mids?
Anyway, that's enough of me leading thoughts, talk about the blind
leading the sighted! Any suggestions?
Remember: quality, quality! not so much quantity. Right up to middle C
or so. C'mon Doc, you used to champion affordable quality before you got
into VV52's and hand built chokes by the dozen!
Thanks in advance,
Grant
Grant Sellek
Adelaide, Australia
grant.sellek@roads.sa.gov.au
=========================================================================
From: "Doc B." <bottlehead@silverlink.net>
Subject: Re: Bass/lower-mid tube amp for Quality not Quantity?
Date: Sat, 23 May 1998 09:10:28 -0700
Source: Sound Digest Archive v01.n290
>
>Remember: quality, quality! not so much quantity. Right up to middle C
>or so. C'mon Doc, you used to champion affordable quality before you got
>into VV52's and hand built chokes by the dozen!
>
OK, wise guy.
The smug answer is build the treble amp so it can play full range and save
yourself a bunch of trouble....
But if you must:
First off, you're running that poor woofer so high that you'll need an amp
that integrates tonally with your treble amp. It will be a midrange/bass
amp, not a bass amp.
Second, If you want cheap bass drive, and you don't have a tube stash (211,
845, 300B), PP is probably a good approach, but it ain't gonna be as good as
SE because you're running the woofer so high.
You mention IT coupled 46 class B blah blah exotica amps, but that fact that
you're looking for guidance instead of building every possible iteration of
an amp and listening to it, then deciding for yourself, indicates you
probably want something a little less tweaky.
Here's something to try.
First dig up an old receiver. I assume you do not have old iron on hand, so
a receiver will give you a good supply of iron for cheap. Fisher, Scott,
Eico, Dynaco, Sansui, Kenwood (the Japanese power trannies are pretty
worthless though), whatever.
Gut the sucker for its power trans and OT's. The OT's will probably be 6-9K.
Close enough for jazz.
Now accept the fact that a good cheap tube is a Chinese 2A3. If that is too
pedestrian, you'll want to learn all there is to know about the 6CK4. Forget
the Svetlana's, they have too high a plate resistance to be easy to find
iron for.
Build this amp on a piece of wood. No sense wasting good chassis until you
get what you want.
Pick a standard Class A operating point like 250V and 60mA.
Get some chokes, 30H minimum. Don't forget, a decent SE OT that you may have
on hand makes a good plate loading choke if it has decent inductance,
usually a lot better than some surplus filter choke. Find some cheap oil
poly motor start caps, at least 4 mfd.
Build a PP 2A3 parafeed. A bunch of people will say PP parafeed has no
advantage, I say build it, find out that it probably sounds better - anyway,
decide for yourself, and smile smugly, knowing that you *know* and they just
*babble*, as they probably haven't even tried it, and are talking through
their hat, much like I am right now.
The parafeed wiring is no big deal, treat it like two opposed parafeed SE
amps circuit-wise. Cathode bias, please.
Drive those 2A3s with a simple direct coupled differential circuit, with
active loads. 5670s are .50 each at AES and sound great, have plenty of
gain, and can run decent current, like 150V at 8-9 mA. You could buy our
boards, but if you're going on the cheap, just steal the schemo for the load
from the Blues Master. If you don't have the B+ to direct couple (around
450V), well, don't. Cap couple it and call it good.
The active loads should balance the drive stage like nobody's business, and
I bet the parafeed gives great resolution.
PS? Choose your poison. Use the tube rectifier from the receiver, if it came
with one, or use the cheap and effective 1N4948 fast recovery diode. You
will soon have a bunch of nice filter caps, eh? If the supply was cap input
and the rectifier was full wave and the current rating was beefy, consider a
fullwave bridge with choke input. That may put you in the ballpark for a
direct coupled amp.
See, I can still cheap out with the best of 'em.
Doc B.
=========================================================================
From: Tim Reese <reese@nmr.MGH.harvard.EDU>
Subject: RE: Bass/lower-mid tube amp for Quality not Quantity?
Date: Sat, 23 May 1998 20:09:06 -0400 (EDT)
Source: Sound Digest Archive v01.n290
Grant asked
>And if I do try to get "decent sized iron" for this task from an unused
>old amp, how do I gauge "feeble" from "well-proportioned"?
Ok, I have a few around - I'd guess that my Sansui 1000A and Fisher 400
outputs are "well proportioned". No scale on hand, but their iron is
2.85x3.35x2.1 = 20 in^3 and 2.5x3x2.1 -15.75 in^3
respectively. From the density of iron, thats 2500g or 5.6lb and 2000g or
4.4lb. Guessing from the appearance of some other amps I have on hand, EICOs
and 6BQ5 Sansui look like about 3.5lb, Scotts about 6 or 6.5lb.
I think when the others are refering to "feeble" outputs, they mean like my
Lafayette 6BQ5 amp, 2.25x1.15x2 = 5.1in^3, 661gm or 1.4lb. A lot smaller.
This is similar to the size of, say, a 6.3V 3A filament transformer.
Hope this is helpful. cheers tr
- ----------------------------------------------------------------------
Tim Reese, MGH NMR Center reese@nmr.MGH.harvard.edu
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@roads.sa.gov.au>
Subject: RE: Bass/lower-mid tube amp for Quality not Quantity?
Date: Sat, 23 May 1998 23:50:52 +0930
Source: Sound Digest Archive v01.n290
Thanks Torbjorn. That looks like a really neat idea. There certainly
isn't much money involved!
Although I didn't have in mind to absolutely cheapskate the amp, this
idea might take some beating. It's triode, it's class A, it's no
feedback, and its power is about the level I was thinking of, certainly
no less.
Anyone want to try and beat this?
To spend a little more on it, the obvious first step would be to
purchase quality OPT's. Or is that not so important with this type of
amp?
BTW, if we're into triode PP, just where do you get good OPT's? (OK, I
know one source: Lundahl). Any others?
And if I do try to get "decent sized iron" for this task from an unused
old amp, how do I gauge "feeble" from "well-proportioned"?
Grant Sellek
Adelaide, Australia
grant.sellek@roads.sa.gov.au
> -----Original Message-----
> From: Torbjųrn Lien [mailto:mdrivekl@online.no]
>.... since bass and musicality is
> the issue
> here, limit yourselves to class "A" PP with triodes.
>
> Find and buy/get/steal etc. a cheap integrated
> with "decent" sized iron. Save the X-formers and throw the
> rest away. Then, buy some 6BL7's,or 6BX7's and rebuild yourselves a
> 4-5W PP class "A" amp, using 2 of the BL/BX -types pr. output
> paralelled..
> Use your favorite voltage tubes upstream or some SL/SN7's.
=========================================================================
From: "Doc B." <bottlehead@silverlink.net>
Subject: Re: Bass/lower-mid tube amp for Quality not Quantity?
Date: Sun, 24 May 1998 09:43:47 -0700
Source: Sound Digest Archive v01.n290
>
>Hi Doc, I appreciate you coming in on my cheeky invite. That's right,
>low-mid/bass. Imagine you wanted an amp for the bass unit of an
>Exemplar. (Ahem)
>
Now this is a whole different animal. Why would you want to build two amps
for a 103 dB speak?
Build our 45 parafeed amp from Nov 97 VALVE, using a 6CK4 if you can't find
45's, and be very happy. You will spend so much effort getting the crossover
right that you won't have a lot of energy left for amp tweaking ;^)>.
I haven't really been blowing a horn about that amp, because I use the
Whamos, but if you only need a couple watts for a horn speak, it is a
fabulous amp. In fact, Tucker and I have been taking orders for some custom
built units, using this basic design with a few proprietary tweaks. They are
tremendous with the eXemplars and with Lowther Medallions, and they even ran
the Ariels!
>Integrates tonally? Good point. I assumed, perhaps wrongly, that tonal
>differences between a 2" Ti diaphragm and a 15" paper cone (it's been
>done before; ask Mr Tucker) would swamp the integration issues between
>amps.
Actually the eXemplars have quite high enough resolution to show very small
differences in amplifiers, as do Ariels, Medallions and Whamos. *Everything*
matters, from the front end quality to the humidity on a given day (but
that's a whole 'nother subject).
>OK, so SE's musical strengths become evident by 500Hz. Good input. I
>didn't know that. Would I be drawing too long a bow to conclude from
>your choice that PP vices are less of an issue in the lower mids than in
>the upper mids/treble? Particularly vices relating to the phase
>splitter?
I was taking this approach to be agreeable, and assumed less than 100+ dB
efficiency levels. Also it's easier to scrounge a PP amp than an SE in a lot
of ways. I am actually in the small camp who thinks SE bass can be much
better than PP bass with some care in design (and a dose of parafeed!)
>
>> Here's something to try.
>> First dig up an old receiver. I assume you do not have old
>> iron on hand,
>
>Correct. The junkers I have include iron that is officially 'feeble' by
>the Tim Reese Calculation.
I don't know how much help I was, as I realize that Fishers and Eicos aren't
that common in Oz, but I assume there must be some sort of old stuff about.
I also hear there are some damned good iron winders downunda.
>
> so
>> a receiver will give you a good supply of iron for cheap.
>> Gut the sucker for its power trans and OT's.
>> Close enough for jazz.
>
>Er, what does that last sentence mean?
Oh nothing. Just a Yank slang phrase, referenced to a musician blowing the
wrong note. I meant the iron won't be optimal, but it will serve the purpose
of eXperiment.
>> Pick a standard Class A operating point like 250V and 60mA.
>> ....Get some chokes, 30H minimum... Find some cheap oil
>> poly motor start caps, at least 4 mfd.
>> Build a PP 2A3 parafeed.
>
>Wow! OK! Any reason not to use the active load circuit? Otherwise I'd be
>getting the retard coil made for me.
I would like to see someone do this. We keep talking about it, but to my
knowledge the only output tube it's been done with is the 417A in the Potato
amp.
Bear in mind you need about two times the plate to filament voltage above
the load, so you're looking at a much higher B+, particularly if you direct
couple the whole amp (700V). You will need to heatsink the MJE 350. You
don't need this with a choke.
So whether it's cheaper to get a plate choke made (make damned sure your
winder understands this is a retard coil, not a filter choke) or come up
with a higher voltage supply would be the determining economic factor. The
loads are very inexpensive.
>> You could buy our boards,
>
>Emma Chissett? Obviously, I'm at least up for a VALVE issue or two...
$25 the pair, a bargain considering it comes with a 30 page manual by Buddha
Camille.
>If I got this circuit working, would it be worth building on? Like,
>better OPT? Changing to IT phase splitter one day?
Yes, you would hear improvements with better iron, no doubt. Wouldn't a
nickel Brooklyn B-14 with 6CK4s be cool? My choice would be to stick with
direct coupled differential driver, but you could certainly play, that's the
main idea.
>
>I get the impression that you have provided me with the "next step up"
>option, quality-wise, compared to the 12BX7 PP that Torbjorn very
>helpfully suggested.
Don't discount Torbjorn's idea. His point that a person needs to push
themselves from designing on paper all the time to trying some circuits for
real is terribly important. As we say around these parts -- "go build
somethin!"
You can't judge whether his idea will work better than mine in your
particular application unless you build them and listen to them both.
Doc B.
=========================================================================
From: "=?ISO-8859-1?Q?Torbj=F8rn_Lien?=" <mdrivekl@online.no>
Subject: Re: Bass/lower-mid tube amp for Quality not Quantity?
Date: Sun, 24 May 1998 17:08:37 +0200
Source: Sound Digest Archive v01.n290
Hello Grant,-
You wrote:
...........
> I get the impression that you have provided me with the "next > step
up" option, quality-wise, compared to the 12BX7 PP that > Torbjorn very
helpfully suggested.
>
> Grant
If you re-read my letter, you'll find that my m a i n point is: It
matters more h o w you do it, than what you do it with.Let me add,-it
matters the most that you get started
on something.Anything.Again: Nothing is more valuable and educating
than real life experience.....
So, now you have got two approaches, and I bet you can think of one or
two more yourselves. Just go ahead. I can assure you that it takes some
labour-hours and some trial'n error
before you get satisfied,-maybe working yourselves through "some" amps
too. But why hesitate,-construction and building
amps has only limited value on paper. You has to start some
sound practices (Uh,-bad pun!) to know.
:TL
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@roads.sa.gov.au>
Subject: RE: Bass/lower-mid tube amp for Quality not Quantity?
Date: Sun, 24 May 1998 22:03:12 +0930
Source: Sound Digest Archive v01.n290
> -----Original Message-----
> From: Doc B. [mailto:bottlehead@silverlink.net]
>
> First off, you're running that poor woofer so high that
> you'll need an amp
> that integrates tonally with your treble amp. It will be a
> midrange/bass amp, not a bass amp.
Hi Doc, I appreciate you coming in on my cheeky invite. That's right,
low-mid/bass. Imagine you wanted an amp for the bass unit of an
Exemplar. (Ahem)
Integrates tonally? Good point. I assumed, perhaps wrongly, that tonal
differences between a 2" Ti diaphragm and a 15" paper cone (it's been
done before; ask Mr Tucker) would swamp the integration issues between
amps. I only mentioned that 'exotic' 46 class B with integration in
mind, because possible treble amps include 45 and 46, SE. So it has
crossed my mind, but something (other than experience) told me that
integrating amp tone is not the weak link in the integration chain,
compared to speaker driver tone. So your experienced perspective is very
useful news to me.
> Second, If you want cheap bass drive, and you don't have a
> tube stash (211,
> 845, 300B),
nothing could be truer (sigh)
> PP is probably a good approach, but it ain't
> gonna be as good as
> SE because you're running the woofer so high.
OK, so SE's musical strengths become evident by 500Hz. Good input. I
didn't know that. Would I be drawing too long a bow to conclude from
your choice that PP vices are less of an issue in the lower mids than in
the upper mids/treble? Particularly vices relating to the phase
splitter?
> Here's something to try.
> First dig up an old receiver. I assume you do not have old
> iron on hand,
Correct. The junkers I have include iron that is officially 'feeble' by
the Tim Reese Calculation.
so
> a receiver will give you a good supply of iron for cheap.
> Gut the sucker for its power trans and OT's.
> Close enough for jazz.
Er, what does that last sentence mean?
> Now accept the fact that a good cheap tube is a Chinese 2A3.
OK. Who was it that got so excited about this tube in a PP amp recently?
I think he had it ITC to a 5842.
> If that is too pedestrian,.. the 6CK4. Forget
> the Svetlana's,
OK. Yes, I've had a good hard look at the 6CK4 recently as a driver tube
option. And seen the 6CK4 PP five-watter in jcm's Fi Primer. And Grover
was quite impressed with its sound when he popped it into his best amp a
while back.
> Pick a standard Class A operating point like 250V and 60mA.
> ....Get some chokes, 30H minimum... Find some cheap oil
> poly motor start caps, at least 4 mfd.
> Build a PP 2A3 parafeed.
Wow! OK! Any reason not to use the active load circuit? Otherwise I'd be
getting the retard coil made for me.
> ...Cathode bias, please.
> Drive those 2A3s with a simple direct coupled differential
> circuit, with
> active loads...
> You could buy our boards,
Emma Chissett? Obviously, I'm at least up for a VALVE issue or two...
> ... the B+ to direct couple (around 450V)...
> PS? Choose your poison. ...If the supply was cap input, consider a
> fullwave bridge with choke input. That may put you in the
> ballpark for a direct coupled amp.
>
> See, I can still cheap out with the best of 'em.
>
> Doc B.
>
Thanks a lot Doc! This is a really interesting lead. I'm going to try
and draw out what you wrote.
If I got this circuit working, would it be worth building on? Like,
better OPT? Changing to IT phase splitter one day?
I get the impression that you have provided me with the "next step up"
option, quality-wise, compared to the 12BX7 PP that Torbjorn very
helpfully suggested.
Grant
Grant Sellek
Adelaide, Australia
grant.sellek@roads.sa.gov.au
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: Bass/lower-mid tube amp for Quality not Quantity?
Date: Sun, 24 May 1998 20:40:10 GMT
Source: Sound Digest Archive v01.n291
On Sun, 24 May 1998 09:43:47 -0700, "Doc B."
<bottlehead@silverlink.net> wrote:
>*Everything*
>matters, from the front end quality to the humidity on a given day (but
>that's a whole 'nother subject).
Don't get me started on that one. The live sound rig I work with is
very susceptible to changes caused by humidity, temperature, and
barometric pressure. It sounds best when the humidity (in Little
Rock) reaches New Orleans levels of steaminess, 'cause that seems to
damp the top end some (no pun intended...). When it's dry, or cold, I
spend all night playing with the graphic EQ chasing annoying HF
thingies.
I think I'm getting a triple-shot of this, 'cause the weather affects
not only the sound in the room, but also the performance of the
microphones and speakers. It all adds up.
- --dnb
=========================================================================
From: "Lynn T. Olson" <lynno@teleport.com>
Subject: Re: Bass/lower-mid tube amp for Quality not Quantity?
Date: Mon, 25 May 1998 02:47:42 -0700
Source: Sound Digest Archive v01.n291
>I haven't really been blowing a horn about that amp, because I use the
>Whamos, but if you only need a couple watts for a horn speak, it is a
>fabulous amp. In fact, Tucker and I have been taking orders for some custom
>built units, using this basic design with a few proprietary tweaks. They are
>tremendous with the eXemplars and with Lowther Medallions, and they even ran
>the Ariels!
>
>Doc B.
Yup, I agree. No way should a 1.56 watt amp "drive" a 92dB/metre 4 ohm
speaker in a 17 by 27 by 11 foot room. But it did a pretty impressive job,
at least on female vocals. No tube sounds like a 45, especially in parafeed
...
Lynn T. Olson
E-mail: lynno@teleport.com
Ariel Speaker Page: http://www.teleport.com/~lynno/Ariel.htm
=========================================================================
From: "Conrad Drake" <conrad.drake@intellect.com.au>
Subject: Re: Bass/lower-mid tube amp for Quality not Quantity?
Date: Mon, 25 May 1998 08:59:17 +0800
Source: Sound Digest Archive v01.n291
I have to agree with Grant - at least out here in West Oz. Old stuff is rare & expen$ive.
There is good new iron available, but like all good new iron it ain't cheap. Especially if you've s
till got to freight it!
Add to this that local* intro kits are, AFAIK, unavailable and it all makes entry level (me)/experim
entation(grant) a bit daunting.
The only commonly available power audio iron is that used for 100V and 70V PA work. Which has to be
parafed.
(Although I did find a tranny with dual HT windings which I could PP, I think - any opinions?)
Conrad D
* US kits are right out - if I want delivery & customs clearance this year it's got to be airfreight
. Plus our $ has just slipped gracefully from 84c US to 63c US :-( :-( :-( :-( :-( :-( :-(
"Doc B." <bottlehead@silverlink.net> 05/25 12:43 am >>>
>> Here's something to try.
>> First dig up an old receiver. I assume you do not have old
>> iron on hand,
>
>Correct. The junkers I have include iron that is officially 'feeble' by
>the Tim Reese Calculation.
I don't know how much help I was, as I realize that Fishers and Eicos aren't
that common in Oz, but I assume there must be some sort of old stuff about.
I also hear there are some damned good iron winders downunda.
=========================================================================
From: "Johari Yip" <hfyip@pacific.net.sg>
Subject: Re: Bass/lower-mid tube amp for Quality not Quantity?
Date: Mon, 25 May 1998 13:14:33 +0800
Source: Sound Digest Archive v01.n291
- ----------
> From: Conrad Drake <conrad.drake@intellect.com.au>
> To: sound@deliverator.io.com
> Subject: Re: Bass/lower-mid tube amp for Quality not Quantity?
> Date: Monday, May 25, 1998 8:59 AM
> I don't know how much help I was, as I realize that Fishers and Eicos
aren't
> that common in Oz, but I assume there must be some sort of old stuff
about.
> I also hear there are some damned good iron winders downunda.
Lucas Cant of Black Art for one.
Johari
=========================================================================
From: pitaro@ozemail.com.au
Subject: Re: Bass/lower-mid tube amp for Quality not Quantity?
Date: Wed, 27 May 1998 12:24:11 EST
Source: Sound Digest Archive v01.n293
** Reply to note from "Sellek, Grant (TSA)" <Grant.Sellek@roads.sa.gov.au> Sat, 23 May 1998 19:44:52
+0930
>
> Dear all,
>
> this is a semi-hypothetical, so feel free to make wild suggestions as
> well as relate any practical experience. ;-)
>
> For biamping a sensitive bass speaker, crossing over say 500-1000hz,
> what options are there for a **fairly economical** DIY amp that has
> really good sound quality (or potential)? Watts are not an issue. The
> range this amp will handle includes a fair amount of vocal and
> instrumental reproduction, so tonal balance and accuracy are important
> (so please don't mistake it for a subwoofer amp which brings to mind
> kick drums and bass guitars).
(snip)
Hi Grant,
Maybe if I tell you what I'm planning, it might spur some ideas for you. I
currently have a pair of VOT's driven by a Reichert 300B amp through an
Altec crossover.
I also have a old pair of Leak TL12 "point one" amps. These are triode
connected PP KT66 amps using Partridge transformers. They produce 12 Watts
but have 20dB of feedback to reduce distortion to 0.1%. They produce
really strong tight bass on the VOTS and are more extended than the 300B
amps in both extremes, but just don't have the detail and delicacy of a
300B.
I intend to bi-amp using the TL12's on the 416 and the 300B on the
908/511B horn. I'll be paralleling the output from the preamp I'm working
on, and filter the frequencies to each amp at the input of each amp.
Hopefully the capicitor required to do that will be quite small (I haven't
worked it out yet).
Hopefully this is food for thought.
Regards,
Harry Pitaro
+-----------------------+---------------------------------------------+
| Melbourne, Australia | A good discussion is like a miniskirt; |
| | Short enough to retain interest |
| pitaro@ozemail.com.au | and long enough to cover the subject. |
+-----------------------+---------------------------------------------+
=========================================================================
From: Finn Hammer <f-hammer@post5.tele.dk>
Subject: Bass, midrange and treble
Date: Wed, 25 Feb 1998 07:27:51 +0100
Source: Sound Digest Archive v01.n200
Speaking of speakers, in reviews and elsewhere, the frequency range is
often divided into Bass, Midrange and Treble.
Some inspired reviewer sometimed tries to make more sence by speaking
about low, or even _lower_ midrange etc.
It has often struck me as an inaccurate way of trying to make a point.
So the question goes like this: is there consensus on where the one
stops, and the other takes over?
I downloaded the function generator from the marchand site, It is nice
to have this reference handy at the PC, everybody should have one.
http://www.marchandelec.com/articles.htm
Thanks to Mark for this lead.
Finn
- --
HOME OF
Tractrix Horns, Tube Amps,
Fieldcoil Loudspeakers and Computer Graphics
http://home5.inet.tele.dk/f-hammer/
=========================================================================
From: "PEARL Cust Serv" <custserv@pearl-hifi.com>
Subject: Bass Qualities
Date: Tue, 08 Dec 1998 00:01:27 -0700
Source: Sound Digest Archive v01.n527
Dear David:
Would you care to expand that last paragraph somewhat. I don't think
that I agree with you what you've said and would appreciate more
information. Thanks..
Bill Perkins, PEARL Inc.
2528 19 St. S.W., Calgary, Ab.,
Canada T2T 4X3
Ph. 1 403 244 4434 Fx. 1 403 244 9026
- ----------
>From: "David B. Klein" <dklein@microtec.net>
>To: davidbarnett@aristotle.net (David Barnett), Kalman Rubinson
<kr4@is2.nyu.edu>, sound@lists.io.com
>Subject: Re: ContraBass kits CHEAP; Bass qualities
>Date: Tue, Dec 8, 1998, 12:04 AM
>
>A 04:22 AM 12/8/98 GMT, David Barnett a écrit :
>>On Mon, 7 Dec 1998 22:01:52 -0500 (EST), Kalman Rubinson
>><kr4@is2.nyu.edu> wrote:
>>
>>>This is confusing unless you assume that all music consists
>>>of sine waves.
>>
>>Isn't that what Mr. Fourier said? <G>
>>
>>--dnb
>>
>>
>
>A wave can be pure sinusoidal fundamental yet be distorted in the time
>domain if there is group delay. This can also take the form of amplitude
>hysteresis in which the initial cycle(s) of the tone are compressed
>although they arrive at the correct time. They can also continue to
>oscillate after being excited. All of these forms of distortion can occur
>without the existence of spurious harmonics.
>
>dbk
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: Bass Qualities
Date: Tue, 08 Dec 1998 02:06:23
Source: Sound Digest Archive v01.n527
A 12:01 AM 12/8/98 -0700, PEARL Cust Serv a écrit :
> Dear David:
> Would you care to expand that last paragraph somewhat. I don't think
>that I agree with you what you've said and would appreciate more
>information. Thanks..
>
>
> Bill Perkins, PEARL Inc.
> 2528 19 St. S.W., Calgary, Ab.,
> Canada T2T 4X3
> Ph. 1 403 244 4434 Fx. 1 403 244 9026
>
>----------
>>From: "David B. Klein" <dklein@microtec.net>
>>To: davidbarnett@aristotle.net (David Barnett), Kalman Rubinson
><kr4@is2.nyu.edu>, sound@lists.io.com
>>Subject: Re: ContraBass kits CHEAP; Bass qualities
>>Date: Tue, Dec 8, 1998, 12:04 AM
>>
>
>>A 04:22 AM 12/8/98 GMT, David Barnett a écrit :
>>>On Mon, 7 Dec 1998 22:01:52 -0500 (EST), Kalman Rubinson
>>><kr4@is2.nyu.edu> wrote:
>>>
>>>>This is confusing unless you assume that all music consists
>>>>of sine waves.
>>>
>>>Isn't that what Mr. Fourier said? <G>
>>>
>>>--dnb
>>>
>>>
>>
>>A wave can be pure sinusoidal fundamental yet be distorted in the time
>>domain if there is group delay. This can also take the form of amplitude
>>hysteresis in which the initial cycle(s) of the tone are compressed
>>although they arrive at the correct time. They can also continue to
>>oscillate after being excited. All of these forms of distortion can occur
>>without the existence of spurious harmonics.
>>
>>dbk
>
I'm not sure what you find unclear about this. Could you be more specific?
dbk
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: Bass qualities - was ContraBass kits CHEAP
Date: Tue, 08 Dec 1998 18:42:25 -0800
Source: Sound Digest Archive v01.n529
Bert Doppenberg wrote:
> > Fast bass in my opinion are bass speakers who are capable to produce the
> > harmonics of the low frequencies accurate. This is mostly the problem with
> > bass speakers with a high moving mass and/or a weak magnet.
then Douglas Purl wrote:
> This is intuitively correct, but absolutely categorically incorrect.
> Increasing the moving mass reduces sensitivity. It does not alter
> bandwidth. Repeat after me: Increased mass does not alter bandwidth. I
> would wager 99.9% of audiophiles harbor this misconception.
...
Just to be clear, Bert did not say that high moving mass alters
bandwidth. At most he implied that high mass is *associated with*
altered bandwidth and/or distortion and/or other effects on harmonics
of LF signals. This is reasonable; increased mass is usually in the
form of thicker cones which implies a host of effects - wavespeed,
impedance ratio between cone and surround, stiffness, damping, etc ad
inf. Increased mass also means smaller boxes for the same frequency
response, and less propagation of box resonances through the cone for
example. And lower efficiency, which means the amplifier operates in a
different regime. And...
OK, I'll quit now. But the observation that high cone mass is
associated with different sound is surely plausible?
- -Paul Joppa
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: Bass qualities; was .. ContraBass kits CHEAP
Date: Tue, 08 Dec 1998 19:12:38 -0800
Source: Sound Digest Archive v01.n529
Greg Monfort wrote:
>
> Has the definition for transient response changed over the years?
Yes indeed.
> It used to be defined as the driver's ability to faithfully follow
> the attack (rise time) of a signal and let it go once it stopped
> (decay time). ...snip...
In the '50s, speakers (and probably other components) often had severe
resonances, much greater than anyone today would tolerate. Woofer
resonance at 60 Hz with a QT greater than 2 was not uncommon; bass
reflex designs with such woofers split the peak leaving two resonances
which one hoped were smaller. Transient response then referred to the
envelope of the signal, not the waveform. Envelope startup and decay
can take enough time (many milliseconds) to be perceptable even
according to the measurements of psychoacousticians. The confusion
between envolope and waveform persists today, a significant source of
the confusion in this thread, IMHO. While the old meaning is more
amorphous, it does correlate better with perception, again IMHO. For
the most part, we perceive an "attack" which integrates the signal
properties over some milliseconds. The leading edge of the waveform,
say of a drum, has an effect in perception of phase relations and
absolute phase, but it is very far from the whole story of attack
"transient" perception.
- -Paul Joppa
=========================================================================
From: "Mark Donen" <soledadd@worldnet.att.net>
Subject: Bass reflex/Jensen/Onken
Date: Sun, 8 Feb 1998 10:23:58 -0500
Source: Sound Digest Archive v01.n186
Hi,
What is the difference in a bass reflex and a Jensen/Onken style enclosure?
Does the Onken do something that a good ole reflex can't?
Secondly, in discussing this with Dan Marshall, it seems that an Altec
414-8c woofer, although 8ohm rated, has a impedance curve that goes way up.
I'm not sure but maybe as high as 50ohms or so. I am intending to use a
414-8c in a 4 cubic foot bass reflex enclosure driven by a sand 200 watter.
What happens to most ss amps when they see 50 ohms? Is the effective power
reduced by almost a factor of 3? That will not be a problem for my sandy
amp given the efficiency of this driver, but it seems to use a tube amp
with less than 50 watts would indeed be problematic (assuming effective
power is halved for every doubling of impedance).
Thanks a lot,
Mark
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: Re: Bass reflex/Jensen/Onken
Date: Sun, 08 Feb 1998 11:19:02 -0800
Source: Sound Digest Archive v01.n186
Mark Donen wrote:
>
> Hi,
>
> What is the difference in a bass reflex and a Jensen/Onken style enclosure?
> Does the Onken do something that a good ole reflex can't?
They are basically variations on the same theme. The Onken reportedly
has "faster" bass than a standard duct loaded design. Since I have not
built an Onken, I will leave opinions to others who have compared the
two.
>
> Secondly, in discussing this with Dan Marshall, it seems that an Altec
> 414-8c woofer, although 8ohm rated, has a impedance curve that goes way up.
> I'm not sure but maybe as high as 50ohms or so.
I don't remember discussing this aspect. However, this is the case with
all cone-type bass drivers, as well as with duct loaded designs. For
the majority of TS alignments there is an impedance peak above and
another below the box frequency and the box frequency is somewhere
around fs (i. e., for most designs). Here are some random things that
may be helpful in a better understanding of duct loaded systems. (As
an aside, the impedance of a typical 12 inch speaker start to rise
somewhere around 500 Hz and can go up to a fairly high value at higher
frequencies. Zobel networks are designed to break in at this higher
frequency where the impedance starts to rise again. This provides a
better behaved impedance for passive crossover designs). The impedance
at box frequency is low, being very near the VC dc resistance, whereas,
the free-air resonant frequency impedance of bass drivers rise to fairly
high impedance levels at resonance. In most designs the box is tuned
somewhere in the neighborhood of fs and box tuning dominates the overall
impedance. Consider the cone/suspension as a parallel tuned circuit
with its Q determined by suspension losses, VC dc resistance, magnetic
motor strength, etc., and consider the box as a series tuned circuit.
It also has a Q associated with it, but lets not go into that here. For
maximally-flat fourth order Butterworth alignment, the box is tuned to
fs. This produces an overall impedance curve that dips to near the VC
dc resistance at fs/box freq and exhibits impedance peaks on either
side.
I am intending to use a
> 414-8c in a 4 cubic foot bass reflex enclosure driven by a sand 200 watter.
> What happens to most ss amps when they see 50 ohms? Is the effective power
> reduced by almost a factor of 3? That will not be a problem for my sandy
> amp given the efficiency of this driver, but it seems to use a tube amp
> with less than 50 watts would indeed be problematic (assuming effective
> power is halved for every doubling of impedance).
This is not anything you have to be concerned with in duct loaded
designs driven by SS amps, which have very low output impedances. The
design takes the impedance variation into account.
Here is a better way of looking at it. It is possible to take the
amplifier's output impedance into account in the enclosure design. (If
the amplifier has a good damping factor, say better than 10, then it
will not likely be much of a problem). The output impedance of the
amplifier will effectively increase the Qts of the speaker, which, in
some cases, is a good thing. This is equivalent to increasing the VC dc
resistance, which is a component affecting the Qts. However, such a
speaker design will perform at its best only with an amplifier
exhibiting a similar damping factor (or with a SS amo with a little
series resistance to lower its damping factor to the value used in the
original design).
Unfortunately (in your case only), the Qts of the 414 is not as low as
many speakers of that vintage, being somewhere around 0.36. That was
the measured value of the units I previously had. A Qts value of 0.383
is the optimum value for maximally flat, fourth order Butterworth
alignment. If you drive a speaker exhibiting a Qts in this optimal
range with a tube amplifier exhibiting considerable output impedance it
will raise the effective Qts of the speaker up into a region that will
call for a Tchebychev alignment. Such an alignment implies a larger
enclosure tuned to a box frequency below fs. Thusly tuned, it is
possible to get the f3 below the speaker fs. Unfortunately, in your
case, four cu. ft. is already too small to achieve fourth order,
maximally-flat Butterworth alignment for a 414, which means that you
cannot expect bass response to 30 Hz. Therefore, an amplifier with
considerable output impedance would be counter productive for your
specific application. If you do want to drive it with a tube amp, I
would recommend that you stay with a good, beefy PP design and maybe use
SE on the top end, if so inclined. With a four cu ft enclosure, you
will have to settle for response maybe somewhere in the 40-50 Hz range,
give or take a bit. This is by guestimate, so don't hold me to precise
numbers here. I forget the VAS of those units. If I find it I will
plug the values int the SS and have a look. In fact I think I saved
them in a parameter file, come to think of it. Another way of saying
it is, don't worry about impedance variations and the power delivered at
the impedance variations which occur at various frequencies, rather,
look at it as a fourth-order, high-pass filter alignement, then satisfy
the TS design parameters and the impedance variations will take care of
themselves. Sorry if this is a bit rambling, but I went back and edited
and expanded it several times and need to move on. As the saying goes,
I'm sorry this is so long, but I didn't have time to make it shorter.
Dan Marshall
>
> Thanks a lot,
>
> Mark
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: Re: Bass reflex/Jensen/Onken
Date: Sun, 08 Feb 1998 14:18:19 -0800
Source: Sound Digest Archive v01.n186
Mark Donen wrote:
>
> Dear Dan,
>
> Thank as always for your conscientious and useful answer. I will have to
> look back to find your exact wording but you said something like the 414s
> can make many amplifiers sound as if they are overloaded.
Yes, indeed, that I did say, but I never determined precisely to what to
attribute this characteristic. I would not relate it to any high
impedance peaks, though. Perhaps it is related to something like the
Xmax capability of the cone suspension being greater than that of the
linear travel capability of the voice coil, or something like that,
though this is only wild speculation.
DM
I guess I'll have
> to try both my JBL 123as and the Altec 414s to see which works out better.
> As you have already explained the JBLs are almost perfectly suited to the
> enclosures I have as far as the potential for the cabinets' and drivers'
> bass extension is concerned. However, I think as you said elsewhere the
> 414s seem to have a better midrange, and a punchier sound in general (5-6dB
> more efficient!). Oh well I guess somewhere down the line I could build
> some petite Onkens for the Altecs! (You don't have the specs do you?) If
> there wasn't a project on the horizon and discontent with what we have we
> would be happy, right?! By the way I have been in contact with Kent Elliott
> about Emilars but have not heard back from him about them --- I asked if
> they had made 500Hz models. On the other hand seems like some people think
> the Altec 805 horn is pretty good (it's 500Hz horn) and I guess this can be
> adapted to 1" drivers. So if the 511s seem to blarey, the 805s are faily
> easy to find -- just got to pay for 'em!
>
> Regards,
>
> Mark
=========================================================================
From: "Mark Donen" <soledadd@worldnet.att.net>
Subject: Re: Bass reflex/Jensen/Onken
Date: Sun, 8 Feb 1998 16:10:04 -0500
Source: Sound Digest Archive v01.n186
Dear Dan,
Thank as always for your conscientious and useful answer. I will have to
look back to find your exact wording but you said something like the 414s
can make many amplifiers sound as if they are overloaded. I guess I'll have
to try both my JBL 123as and the Altec 414s to see which works out better.
As you have already explained the JBLs are almost perfectly suited to the
enclosures I have as far as the potential for the cabinets' and drivers'
bass extension is concerned. However, I think as you said elsewhere the
414s seem to have a better midrange, and a punchier sound in general (5-6dB
more efficient!). Oh well I guess somewhere down the line I could build
some petite Onkens for the Altecs! (You don't have the specs do you?) If
there wasn't a project on the horizon and discontent with what we have we
would be happy, right?! By the way I have been in contact with Kent Elliott
about Emilars but have not heard back from him about them --- I asked if
they had made 500Hz models. On the other hand seems like some people think
the Altec 805 horn is pretty good (it's 500Hz horn) and I guess this can be
adapted to 1" drivers. So if the 511s seem to blarey, the 805s are faily
easy to find -- just got to pay for 'em!
Regards,
Mark
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: Bass reflex/Jensen/Onken
Date: Mon, 9 Feb 1998 09:27:46 +0100 (MET)
Source: Sound Digest Archive v01.n186
At 10:23 08/02/1998 -0500, Mark Donen wrote:
>What is the difference in a bass reflex and a Jensen/Onken style enclosure?
>Does the Onken do something that a good ole reflex can't?
The Onken/Jensen (Grande and Petite) can be calculated as true bass-reflex
(Butterworth 4th order) with an alignment coefficient n = 6.34
The coefficient n is the one in the expression:
Vb = n . Vas . (Qts^2)
The other rule with an Onken/Jensen is that the vents section should have an
area equal to the area of the loudspeaker membrane (in my modified cabinet
it is only 3/4 of that area). The vents have to be also vertical and
symmetrical versus the loudspeaker position. The loudspeaker position have
to be 40 to 54 cm from the floor.
The optimisation of the vents length can be performed tracing the impedance
curve between 10 and 100Hz. The 2 peaks should be of equal height. In fact
as measured on the petite Onken of La Maison de l'Audiophile the peak at
22.5 Hz was at 116 ohms and the one at 60 Hz was at 88 ohms.
Best regards,
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: "P.A. & M. Almeflo" <sd@ljusdal.se>
Subject: RE: Bass reflex/Jensen/Onken
Date: Mon, 9 Feb 1998 17:14:18 +0100
Source: Sound Digest Archive v01.n187
Le Cleac'h J.-M. wrote regarding Onken style enclosures:
>The vents have to be also vertical and
> symmetrical versus the loudspeaker position.
What is the purpose of this arrangement?
Best regards,
Per Arne
=========================================================================
From: Steve Van Osdell <svanos@toast.net>
Subject: Bass Reflex Project
Date: Fri, 10 Apr 1998 18:32:37 -0500
Source: Sound Digest Archive v01.n249
FYI...
I'm about to build a pair of large bass reflex enclosures for my Altec
515-8G's. They'll be finished by next weekend.
They will be from 3/4" Baltic Birch Ply and will be 58" tall, 25" deep, and
30" wide for about 22ft3. I will place the speaker cutout and the port so
that I can add another pair to them later if I chose.
Cabinet will be well braced inside, and will be veneered on the outside.
Decided against HDF for weight reasons.
Total cost of plywood - $168 and a cabinet guy is helping me (or me helping
him) for $150 labor.
I'll let y'all know how they sound.
RCA World's Fair Horns will sit on top crossed at 650 12DB passive.
Steve
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: Re: Bass speaker placement
Date: Thu, 26 Mar 1998 14:14:40 -0800
Source: Sound Digest Archive v01.n231
Joėl NOIROT wrote:
>
> Hi gang,
>
> My wife kindly sent me in the basement with all my stuff with the
> spiders. The good point is that I can do what I want now.
> I want to put a pair of JBL 2245 in a wall which separates two rooms in
> my basement (infinite baffle).
> I have two concerns:
>
> 1) the power handling of the speakers (no load so maybe cone excursion
> problems). Am I right?
>
> 2) the place where to do the holes. Depending on the location of the
> speakers I'll have different bass response in my room. Any opinion on
> that subject?
>
> Thanks in advance
>
> Joel
Hi Joel,
My limited experience with mounting speakers in walls or ceilings is
that you can expect gobs of good, extended bass. I doubt that you need
be concerned with excursion limitations with those speakers unless you
really crank it beyond reason. I have also found that some large
speakers (especially Altecs) like to be driven by a very sturdy
amplifiers and will sometimes sound as though they are being overdriven
when it is the amp going into current limiting. I have not confirmed
this on JBLs but have observed it with Altecs.
As far as speaker placement, of course, in the following order, the side
wall, the floor-wall or ceiling wall and them a full corner placement
will give increasing amounts of bass. If I were you, I would try the
old trick of placing a good subwoofer in the preferred listening spot,
then stroll about the room and note positions where the bass response is
most pleasing and well balanced then place the woofers there. There is
supposed to be a reciprocal relationship in the speaker-listener
positions. It may be a bit more complex with two woofers at different
locations, but I suspect that it may work if you can find two acceptable
locations. Putting a moose of a speaker like the 2245s in a corner may
give you more bass than you care for, or of a different character than
you prefer. Sounds like a fun project.
Dan Marshall
=========================================================================
From: Joėl NOIROT <jnoirot@club-internet.fr>
Subject: Bass speaker placement
Date: Thu, 26 Mar 1998 15:55:33 -0500
Source: Sound Digest Archive v01.n231
Hi gang,
My wife kindly sent me in the basement with all my stuff with the
spiders. The good point is that I can do what I want now.
I want to put a pair of JBL 2245 in a wall which separates two rooms in
my basement (infinite baffle).
I have two concerns:
1) the power handling of the speakers (no load so maybe cone excursion
problems). Am I right?
2) the place where to do the holes. Depending on the location of the
speakers I'll have different bass response in my room. Any opinion on
that subject?
Thanks in advance
Joel
=========================================================================
From: Dave Davenport <dadio@mindspring.com>
Subject: Battery Bias
Date: Wed, 30 Sep 1998 16:22:12 -0400
Source: Sound Digest Archive v01.n434
I am looking at the schematic for Arthur Loesch's phono preamp in SP-3 pg.
26. I notice that he uses batteries to bias his second and third stages,
and see that he puts them in the grid circuit rather than in the cathode
circuit as has been discussed here recently. Can someone help me
understand the trade-offs in locating the batteries in the grid circuit
versus in the cathode circuit?
Thanks, Dave
PS I originally posted this last night, but since it didn't appear by this
evening, I reposted it.
=========================================================================
From: Scott Grammer <tubedude@cdc.net>
Subject: Re: Battery Bias
Date: Wed, 30 Sep 1998 17:46:12 -0400
Source: Sound Digest Archive v01.n434
Dave Davenport wrote:
> (snip) Can someone help me
> understand the trade-offs in locating the batteries in the grid circuit
> versus in the cathode circuit?
>
> Thanks, Dave
>
> (snip)
Dave:
Whenever a battery is placed in the cathode circuit for bias purposes, the
battery is being charged by the cathode current of the tube. This may be good
or bad depending on the battery, charging current, temperature of the battery,
etc. Further, the impedance of the battery is interposed in series with the
plate circuit. The grid is left at essentially zero volts dc which makes for
easier coupling. An equivalent circuit (of the battery) might be a resistor,
zener diode, and large capacitor all in parallel, with a small series
resistance in series with the zener. It is a constant voltage form of
self-bias.
When the battery is in the grid circuit there is no charging current, and the
impedance of the battery is not in the plate circuit. The grid is biased
negative with respect to ground, and some form of coupling circuit (tranny,
capacitor) is necessary. It is the common garden variety grid bias, but with a
totally clean grid voltage supply.
In both forms of bias the battery voltage is critical, and must be matched by
some means with the tube and circuit in question in order to achieve the
desired operating point.
True self-bias (with a resistor in the cathode circuit) tends to stabilize
itself throughout large variations in tube gain. A higher plate current will
result in higher bias voltage, which lowers the current. Lower current will
reduce the bias voltage, raising the current.
Hope this helps!
S.G.
- --
Check out TubeDude's Webpage of Vacuum Tube Lore! at
http://www.cdc.net/~tubedude/
Also see my new website, Smoke Free Youth! at
http://www.cdc.net/~tubedude/smokefreeyouth.html
=========================================================================
From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: RE: Battery Bias
Date: Wed, 30 Sep 1998 19:21:09 -0400
Source: Sound Digest Archive v01.n434
this is more of a test than an excuse to picking on scott... :)
we'll see if it gets thru...
see comments below:
> ----------
> From: Scott Grammer[SMTP:tubedude@cdc.net]
> Sent: Wednesday, September 30, 1998 5:46 PM
> To: Dave Davenport
> Cc: sound@lists.io.com
> Subject: Re: Battery Bias
>
>
>
> Dave Davenport wrote:
>
> > (snip) Can someone help me
> > understand the trade-offs in locating the batteries in the grid circuit
> > versus in the cathode circuit?
> >
> > Thanks, Dave
> >
> > (snip)
>
> Dave:
>
> Whenever a battery is placed in the cathode circuit for bias purposes, the
> battery is being charged by the cathode current of the tube. This may be
> good
> or bad depending on the battery, charging current, temperature of the
> battery,
> etc. Further, the impedance of the battery is interposed in series with
> the
> plate circuit. The grid is left at essentially zero volts dc which makes
> for
> easier coupling. An equivalent circuit (of the battery) might be a
> resistor,
> zener diode, and large capacitor all in parallel, with a small series
> resistance in series with the zener. It is a constant voltage form of
> self-bias.
>
actually, it's more like an ideal *voltage source* with small (except
when near-flat or overcharged) series resistance,
small (but apreciable) series inductance.
this makes it superior to a zener because it can source or sink
current on demand.
whether this nuance is terribly important to this discussion ....
maybe we can talk some more...
> When the battery is in the grid circuit there is no charging current,
>
oh, you don't think so....? ;)
ask dave slagle what blown battery goo smells like.
we can't neglect the influences of grid emission current
which can become appreciable when a tube is driven
(or even idles) hard -i.e., highish dissipation.
there may be other effects such as the ac modulation of this current,
especially into clipping, and/or class A2/positive grid current.
in dave's set-up this current was not limited to any great extent because
of his tranny coupling. the low DCR allowed this to happen.
consequently, dave, this might also explain why i haven't seen the effects
of the plate-grid shorts you were seeing in similar tubes....
> and the
> impedance of the battery is not in the plate circuit. The grid is biased
> negative with respect to ground, and some form of coupling circuit
> (tranny,
> capacitor) is necessary. It is the common garden variety grid bias, but
> with a
> totally clean grid voltage supply.
>
> In both forms of bias the battery voltage is critical, and must be matched
> by
> some means with the tube and circuit in question in order to achieve the
> desired operating point.
>
also, as the battery dies, it's terminal voltage drops, which increases
plate current/ plate dissipation.
if you're not careful, the thing could run away on you.
this was also a factor in dave's problem, i think...
> True self-bias (with a resistor in the cathode circuit) tends to stabilize
> itself throughout large variations in tube gain. A higher plate current
> will
> result in higher bias voltage, which lowers the current. Lower current
> will
> reduce the bias voltage, raising the current.
>
right. constant voltage bias does not self correct to the same extent.
bottom-line is that cathode battery bias allows one to keep a pseudo-
cathode-bias arrangement without the need for a bypass capacitor.
the theory is that the battery is a perfect ac short over a wider frequency
range than a resistor/capacitor
i.e. at the low end - where it counts.
not sure about HF though.
i've done impedance tests on various types of batteries (at work, not play)
and they really tend to take off at relatively low frequencies
1K to 10Khz
bob.d.
=========================================================================
From: dslagle@earthlink.net (Dave Slagle)
Subject: RE: Battery Bias
Date: Wed, 30 Sep 1998 20:16:09 -0700 (PDT)
Source: Sound Digest Archive v01.n434
>this is more of a test than an excuse to picking on scott... :)
yo big boy... pick on me....
>this makes it superior to a zener because it can source or sink
>current on demand.
someone else piped in that the cathode battery would never source
current...i dunno... could it be measured??? it seems like a neat thing to
look for... if ya had the technology.
>ask dave slagle what blown battery goo smells like.
the runaway you mention later is worse! thank god those 45's and 50's are
built tough!... I've yet to kill one!
>we can't neglect the influences of grid emission current
>which can become appreciable when a tube is driven
>(or even idles) hard -i.e., highish dissipation.
even at idle is the key here!.... this is in the grid circuit of an output
tube being driven hard!... I think fellow Packer pat... did well with lead
acid cells in the grid of an 845... I was too cheap to try batteris that
like to be charged in a grid circuit... but please note this is NOT how the
loesch circuit is biased!
this is the use of just a battery on an output grid with no current
limiting resistor! the loesch is well protected against such problems...
the voltage divider used to set bias guarentees that....
I could guarentee you a 1K resistor in series would stop any grid current
in the situations when I popped a cell, but that would mess up a lot more
than it would solve.
>in dave's set-up this current was not limited to any great extent because
>of his tranny coupling. the low DCR allowed this to happen.
see above :-)
>also, as the battery dies, it's terminal voltage drops, which increases
>plate current/ plate dissipation.
>if you're not careful, the thing could run away on you.
take note of this with any fixed grid supply!
>this was also a factor in dave's problem, i think...
yeah... I heard a pop... lost 1.5V bias.... heard another pop... another
1.5V gone... it is a runaway... but with warning... not like that poor sap
who fired up his VV30's without bias current and fried a thyratron.... the
tube took 2A of current... the $10 tube died... toooo bad...
fixed bias has to be protected in any form... unless your outputs are tough!
>bottom-line is that cathode battery bias allows one to keep a pseudo-
>cathode-bias arrangement without the need for a bypass capacitor.
a good thought!
>the theory is that the battery is a perfect ac short over a wider frequency
>range than a resistor/capacitor
>i.e. at the low end - where it counts.
this is where I hear it.... but the bypass cap is heard in the hf... Its a
sound, and I am gettng better at hearing it..
>not sure about HF though.
jc are you there??? you have mentioned this problem before...
>i've done impedance tests on various types of batteries (at work, not play)
>and they really tend to take off at relatively low frequencies
>1K to 10Khz
yeah... but what is worse??? what the nicad does or what the cap
does???...to our ears that is...
dave
=========================================================================
From: Scott Grammer <tubedude@cdc.net>
Subject: Re: Battery Bias
Date: Wed, 30 Sep 1998 21:35:23 -0400
Source: Sound Digest Archive v01.n434
Danielak, Robert M wrote:
> this is more of a test than an excuse to picking on scott... :)
Aw c'mon. You guys love to pick on me! (It's ok, I couldn't think of a better
group of folks to be picked on by.)
>
>
> we'll see if it gets thru...
>
> see comments below:
> (snip)
> An equivalent circuit (of the battery) might be a
> > resistor,
> > zener diode, and large capacitor all in parallel, with a small series
> > resistance in series with the zener. It is a constant voltage form of
> > self-bias.
> >
> actually, it's more like an ideal *voltage source* with small (except
> when near-flat or overcharged) series resistance,
> small (but apreciable) series inductance.
>
> this makes it superior to a zener because it can source or sink
> current on demand.
>
> whether this nuance is terribly important to this discussion ....
>
> maybe we can talk some more...
I don't see the battery ever sourcing current because to do so it would have to
overcome the reverse biased resistance of the cathode-grid diode, nominally many
millions, maybe even billions of ohms. Not to mention that in a cathode bias
circuit the plate current would have to cease totally before the battery could
source any current, and event then there's that diode in the way again.
In any case a battery is superior to a zener from a noise standpoint. Also it's
simpler, and I am all for simple elegant circuits.
>
>
> > When the battery is in the grid circuit there is no charging current,
> >
> oh, you don't think so....? ;)
>
> ask dave slagle what blown battery goo smells like.
>
> we can't neglect the influences of grid emission current
> which can become appreciable when a tube is driven
> (or even idles) hard -i.e., highish dissipation.
You are correct.
>
>
> there may be other effects such as the ac modulation of this current,
> especially into clipping, and/or class A2/positive grid current.
Also true. When driven into class A2 (grid positive with respect to cathode)
grid current flows. In fact it can flow just before the zero crossing...
I should have thought of that......Can't.....Think..... Too.....
Much......T...V......
>
>
> in dave's set-up this current was not limited to any great extent because
> of his tranny coupling. the low DCR allowed this to happen.
>
> consequently, dave, this might also explain why i haven't seen the effects
> of the plate-grid shorts you were seeing in similar tubes....
>
> > and the
> > impedance of the battery is not in the plate circuit. The grid is biased
> > negative with respect to ground, and some form of coupling circuit
> > (tranny,
> > capacitor) is necessary. It is the common garden variety grid bias, but
> > with a
> > totally clean grid voltage supply.
> >
> > In both forms of bias the battery voltage is critical, and must be matched
> > by
> > some means with the tube and circuit in question in order to achieve the
> > desired operating point.
> >
> also, as the battery dies, it's terminal voltage drops, which increases
> plate current/ plate dissipation.
> if you're not careful, the thing could run away on you.
>
> this was also a factor in dave's problem, i think...
>
> > True self-bias (with a resistor in the cathode circuit) tends to stabilize
> > itself throughout large variations in tube gain. A higher plate current
> > will
> > result in higher bias voltage, which lowers the current. Lower current
> > will
> > reduce the bias voltage, raising the current.
> >
> right. constant voltage bias does not self correct to the same extent.
>
> bottom-line is that cathode battery bias allows one to keep a pseudo-
> cathode-bias arrangement without the need for a bypass capacitor.
> the theory is that the battery is a perfect ac short over a wider frequency
> range than a resistor/capacitor
> i.e. at the low end - where it counts.
>
> not sure about HF though.
> i've done impedance tests on various types of batteries (at work, not play)
> and they really tend to take off at relatively low frequencies
> 1K to 10Khz
>
> bob.d.
Interesting. I suppose it might be that the "capacitance" at low frequencies is
actually the charging/discharging of the electrolyte, which has a very high
dissipation factor. At high frequencies the dielectric simply can't charge and
discharge fast enough, (it's a chemical reaction that takes time, as opposed to
an electrostatic phenomenon as in a true capacitor) and the impedance rises. I
also imagine that at some higher-still frequency the true capacitance of the
anode and cathode would take over and the impedance would drop again...
Or not...
Always happy to be corrected by someone more knowlegeable... :-)
Cheers!
S.G.
- --
Check out TubeDude's Webpage of Vacuum Tube Lore! at
http://www.cdc.net/~tubedude/
Also see my new website, Smoke Free Youth! at
http://www.cdc.net/~tubedude/smokefreeyouth.html
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: Battery Bias
Date: Thu, 01 Oct 1998 08:35:37 -0400
Source: Sound Digest Archive v01.n435
Dave Davenport wrote:
> I am looking at the schematic for Arthur Loesch's phono preamp in SP-3 pg.
> 26. I notice that he uses batteries to bias his second and third stages,
> and see that he puts them in the grid circuit rather than in the cathode
> circuit as has been discussed here recently. Can someone help me
> understand the trade-offs in locating the batteries in the grid circuit
> versus in the cathode circuit?
It's an opportunity to show how cool you are for using teflon coupling caps.
JL
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: Battery Bias
Date: Wed, 30 Sep 1998 21:37:56 -0700
Source: Sound Digest Archive v01.n436
A few notes below...
Scott Grammer wrote:
...snip...
> Whenever a battery is placed in the cathode circuit for bias purposes, the
> battery is being charged by the cathode current of the tube.
Hence NiCd batteries are often used, as they will take a modest
charging current continuously, dissipating it as heat without damage.
...more snip...
> When the battery is in the grid circuit there is no charging current, and the
> impedance of the battery is not in the plate circuit. The grid is biased
> negative with respect to ground, and some form of coupling circuit (tranny,
> capacitor) is necessary.
What's being described here is the usual approach - the battery
negative terminal is isolated from the grid at AC by a resistor or an
inductance (transformer secondary usually, though a choke would work).
The grid is at a negative voltage and must be coupled by a capacitor.
There is an alternative - the battery can be in the grid circuit
directly, between the input (at ground DC potential) and the grid
itself. The "grid wire" is now large, and might have some
electrostatic pickup and/or capacitance to ground, but both cathode
and input can be referred to ground. Haven't tried this, just seen it
in a book from the 40s.
In either case, alkaline batteries are the logical candidates in
low-level (non-grid-current) circuits; they won't tolerate much
charging, but hold their voltage for years unlike NiCds which lose
about 10% per month. Also in either case, grid current from positive
grid voltage will charge the battery I think (I get confused with the
topology, anyone please correct me if I'm wrong here!) - not a good
idea with alkalines, but I don't know any battery that tolerates
trickle charging without losing charge in storage - does anyone else?
...more snip...
> True self-bias (with a resistor in the cathode circuit) tends to stabilize
> itself throughout large variations in tube gain. A higher plate current will
> result in higher bias voltage, which lowers the current. Lower current will
> reduce the bias voltage, raising the current.
Sometimes called "automatic bias" for this reason.
- -Paul Joppa
=========================================================================
From: Dave Stagner <dstagner@icarus.net>
Subject: Re: Battery Bias
Date: Fri, 2 Oct 1998 10:59:58 -0500 (CDT)
Source: Sound Digest Archive v01.n436
On Wed, 30 Sep 1998, Paul Joppa wrote:
> In either case, alkaline batteries are the logical candidates in
> low-level (non-grid-current) circuits; they won't tolerate much
> charging, but hold their voltage for years unlike NiCds which lose
> about 10% per month. Also in either case, grid current from positive
> grid voltage will charge the battery I think (I get confused with the
> topology, anyone please correct me if I'm wrong here!) - not a good
> idea with alkalines, but I don't know any battery that tolerates
> trickle charging without losing charge in storage - does anyone else?
How about plain old carbon batteries? They take trickle charge EXTREMELY
well... i've had the same carbon batteries in my alarm clock for years,
and it's always up and running for our charming Iowa power outages from
thunderstorms.
- -dave
Practice beautiful randomness and act kind of senseless.
<dstagner@icarus.net>
=========================================================================
From: Alex Mitaru <alexmi@omneon.com>
Subject: battery bias?
Date: Wed, 25 Nov 1998 13:33:12 -0800
Source: Sound Digest Archive v01.n504
Could someone please explain how the battery bias works? If I need 8.5V of
bias
for a 6SN7, can I just use a 9V NiCad? How do I connect it? Is the battery
constantly charging? Sorry for the novice questions...
thanks, alex
Alex Mitaru
- ------------------------------------------------------------------
Principal Engineer (503) 533-0621 ext 228
Omneon Video Networks alexmi@omneon.com
=========================================================================
From: David Home <DHome@creo.com>
Subject: RE: battery bias?
Date: Wed, 25 Nov 1998 16:25:15 -0800
Source: Sound Digest Archive v01.n504
Yes Alex, the battery is constantly charging, positive pole to the cathode.
A 9V NiCd is not actually 9V but around 7.9V. Sure use it in place of your
cathode bias resistor/bypass capacitor that sets a bias of 8.5V, the tube
will hardly know the difference. Do charge the battery before putting it in
the circuit. What is important though is the capacity of the battery. It
should be at least 20X the ideal current of your 6SN7 circuit. So ifyour
tube draws 10ma, then a cell of 0.2AH would be the minimum. I suggest
spending the money and getting high density NiCds from Sylvania or
Panasonic.
Regards, David
-----Original Message-----
From: Alex Mitaru [mailto:alexmi@omneon.com]
Sent: Wednesday, November 25, 1998 1:33 PM
To: sound@lists.io.com
Subject: battery bias?
Could someone please explain how the battery bias works? If
I need 8.5V of
bias
for a 6SN7, can I just use a 9V NiCad? How do I connect it?
Is the battery
constantly charging? Sorry for the novice questions...
thanks, alex
Alex Mitaru
- ------------------------------------------------------------------
Principal Engineer (503) 533-0621
ext 228
Omneon Video Networks
alexmi@omneon.com
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: RE: battery bias?
Date: Wed, 25 Nov 1998 19:57:01
Source: Sound Digest Archive v01.n504
A 04:25 PM 11/25/98 -0800, David Home a écrit :
>Yes Alex, the battery is constantly charging, positive pole to the cathode.
>A 9V NiCd is not actually 9V but around 7.9V. Sure use it in place of your
>cathode bias resistor/bypass capacitor that sets a bias of 8.5V, the tube
>will hardly know the difference. Do charge the battery before putting it in
>the circuit. What is important though is the capacity of the battery. It
>should be at least 20X the ideal current of your 6SN7 circuit. So ifyour
>tube draws 10ma, then a cell of 0.2AH would be the minimum. I suggest
>spending the money and getting high density NiCds from Sylvania or
>Panasonic.
>
>Regards, David
>
> -----Original Message-----
> From: Alex Mitaru [mailto:alexmi@omneon.com]
> Sent: Wednesday, November 25, 1998 1:33 PM
> To: sound@lists.io.com
> Subject: battery bias?
>
>
> Could someone please explain how the battery bias works? If
>I need 8.5V of
> bias
> for a 6SN7, can I just use a 9V NiCad? How do I connect it?
>Is the battery
> constantly charging? Sorry for the novice questions...
>
> thanks, alex
>
> Alex Mitaru
>
>------------------------------------------------------------------
> Principal Engineer (503) 533-0621
>ext 228
> Omneon Video Networks
>alexmi@omneon.com
>
Why not use a Zener reference and an op amp? They would never go bad, as a
batter would.
dbk
=========================================================================
From: peterca@ento.csiro.au
Subject: RE: battery bias?
Date: Thu, 26 Nov 1998 17:04:43 +1100 (EST)
Source: Sound Digest Archive v01.n504
>Why not use a Zener reference and an op amp? They would never go bad, as a
>batter would.
>
>dbk
I'm not sure what the opamp would be for. You could just use a zener of
the appropriate voltage. I only tried that one in a power amp circtuit
with a power zener and didn't particularly like the result although it
wasn't very different from the resistor/cap arrangement.
A friend of mine of swears by LEDs in this application. I can't recall the
details of selecting the right ones etc.
Dr. Peter Campbell (Peter.Campbell@ento.csiro.au)
Div. Entomology, C.S.I.R.O. Ph.61-2-62464053 or -62464158 (w)
Box 1700 Canberra A.C.T. 2601 61-2-62516213 (h)
Australia 61-2-62464173 (fax)
=========================================================================
From: David Home <DHome@creo.com>
Subject: RE: battery bias?
Date: Thu, 26 Nov 1998 08:59:59 -0800
Source: Sound Digest Archive v01.n505
Interesting thoughts Jean-Michel. I have had no problems with battery
heating in my phono amp or line amp, but in both the ratio of capacity to
current is closer to 50X rather then the 20X often quoted. Maybe I saved
myself some grief by buying the high density $$ NiCds. Regards, David
-----Original Message-----
From: Le Cleac'h J.-M. [mailto:lecleach@cgi.ensmp.fr]
Sent: Thursday, November 26, 1998 12:52 AM
To: David Home; 'Alex Mitaru'; sound@lists.io.com
Subject: Re: battery bias?
----------
> De : David Home <DHome@creo.com>
> A : 'Alex Mitaru' <alexmi@omneon.com>; sound@lists.io.com
> Objet : RE: battery bias?
> Date : jeudi 26 novembre 1998 01:25
>
> Yes Alex, the battery is constantly charging, positive
pole to the
cathode.
> A 9V NiCd is not actually 9V but around 7.9V. Sure use it
in place of
your
> cathode bias resistor/bypass capacitor that sets a bias of
8.5V, the tube
> will hardly know the difference. Do charge the battery
before putting it
in
> the circuit. What is important though is the capacity of
the battery. It
> should be at least 20X the ideal current of your 6SN7
circuit. So ifyour
> tube draws 10ma, then a cell of 0.2AH would be the
minimum. I suggest
> spending the money and getting high density NiCds from
Sylvania or
> Panasonic.
An important thing for safety but also for the sound is that
you have to
test that the battery after some hours of use doesn't heat.
This can
happens, even with a large capacity battery if it is fully
charged.
Also you have to know that Ni Cd battery's life is reduced
when the battery
is overcharged.
On my Minor Swing amplifier that use a single WE437, I use a
NiCd battery
(1.6 or 1.8V I don't remember exactly). The first week I use
the cathod
biasing batteriesI was disappointed, the sound was allways
changing.
I noticed that the 750 mAH batteries were hot (the cathod
current is around
30mA).
I have the idea to derive some current. A resistor in
parallel gave bad
results, no stability of the sound.
Then I have the idea to use in parallel on the battery 2 x
1N4004 silicon
rectifiers in series.
Due to the low current through the rectifiers they operate
in the zone
where the slope of the I_V curve chnages.This introduce a
very simple and
good stabilization of the battery voltage.
If the battery discharge (state 1), there is less current
through the
rectifiers, so the battery charges.
If the battery is fully charged (state 2), there is more
current through
the rectifiers. As the change of slope is in fact a zone of
high curvature
there is not kink passing from state (1) to state (2) in
fact I think the
battery is never lowcharged nor overcharged.
I add also an excellent little unpolarized capacitor in
parallel on the
rectifiers.
Now I am very happy with the sound, allways the same, even
in the 1st
minute ( I use that amplifier as an headphone amplifier for
my excellent
Sony CDR 3000 headphone and also as a tweeter amplifier with
my Onken
tweeters).
Best regards,
Jean-Michel Le Cleac'h.
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: battery bias?
Date: Thu, 26 Nov 1998 09:52:29 +0100
Source: Sound Digest Archive v01.n505
- ----------
> De : David Home <DHome@creo.com>
> A : 'Alex Mitaru' <alexmi@omneon.com>; sound@lists.io.com
> Objet : RE: battery bias?
> Date : jeudi 26 novembre 1998 01:25
>
> Yes Alex, the battery is constantly charging, positive pole to the
cathode.
> A 9V NiCd is not actually 9V but around 7.9V. Sure use it in place of
your
> cathode bias resistor/bypass capacitor that sets a bias of 8.5V, the tube
> will hardly know the difference. Do charge the battery before putting it
in
> the circuit. What is important though is the capacity of the battery. It
> should be at least 20X the ideal current of your 6SN7 circuit. So ifyour
> tube draws 10ma, then a cell of 0.2AH would be the minimum. I suggest
> spending the money and getting high density NiCds from Sylvania or
> Panasonic.
An important thing for safety but also for the sound is that you have to
test that the battery after some hours of use doesn't heat. This can
happens, even with a large capacity battery if it is fully charged.
Also you have to know that Ni Cd battery's life is reduced when the battery
is overcharged.
On my Minor Swing amplifier that use a single WE437, I use a NiCd battery
(1.6 or 1.8V I don't remember exactly). The first week I use the cathod
biasing batteriesI was disappointed, the sound was allways changing.
I noticed that the 750 mAH batteries were hot (the cathod current is around
30mA).
I have the idea to derive some current. A resistor in parallel gave bad
results, no stability of the sound.
Then I have the idea to use in parallel on the battery 2 x 1N4004 silicon
rectifiers in series.
Due to the low current through the rectifiers they operate in the zone
where the slope of the I_V curve chnages.This introduce a very simple and
good stabilization of the battery voltage.
If the battery discharge (state 1), there is less current through the
rectifiers, so the battery charges.
If the battery is fully charged (state 2), there is more current through
the rectifiers. As the change of slope is in fact a zone of high curvature
there is not kink passing from state (1) to state (2) in fact I think the
battery is never lowcharged nor overcharged.
I add also an excellent little unpolarized capacitor in parallel on the
rectifiers.
Now I am very happy with the sound, allways the same, even in the 1st
minute ( I use that amplifier as an headphone amplifier for my excellent
Sony CDR 3000 headphone and also as a tweeter amplifier with my Onken
tweeters).
Best regards,
Jean-Michel Le Cleac'h.
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: battery bias?
Date: Sat, 28 Nov 1998 13:05:17 -0800
Source: Sound Digest Archive v01.n507
David B. Klein wrote:
>
> Why not use a Zener reference and an op amp? They would never go bad, as a
> batter would.
Two reasons: zeners are noisy, and opamps have global negative
feedback.
- -Paul Joppa
=========================================================================
From: Scott Grammer <tubedude@cdc.net>
Subject: Re: Battery Bias -NiMH cells & (no) thanks for the memory
Date: Fri, 02 Oct 1998 14:53:01 -0400
Source: Sound Digest Archive v01.n436
trs@carlsmith.com wrote:(snip)
> Recently nickel-metal-hydride cells have begun appearing
> on the hobby market; these cells supposedly do not have a
> memory problem, have a higher power density that nicads
> and last longer. If anyone wants a mail-order source for
> NiMH cells, please post me.
NMH cells also are more suited for low current long duration use, but on
the down side they have a higher ESR.
Cheers!
S.G.
- --
Check out TubeDude's Webpage of Vacuum Tube Lore! at
http://www.cdc.net/~tubedude/
Also see my new website, Smoke Free Youth! at
http://www.cdc.net/~tubedude/smokefreeyouth.html
=========================================================================
From: trs@carlsmith.com
Subject: Re: Battery Bias -NiMH cells & (no) thanks for the memory
Date: Fri, 2 Oct 1998 7:56:07 -1000
Source: Sound Digest Archive v01.n436
Those of us that race radio-controlled cars as a hobby
(actually, I only do it for my kid. . . ) know that there are
some very sophisticated low-impedance "sub-C" nicad cells
available now at low prices, but all generally remain plagued
by "memory" - the tendency of a nicad cell, when repeatedly
discharged only partially, to act as if its capacity is limited to
the range between full charge and that partial discharge
point. Regular, complete discharge ("cycling") is believed to
be important to avoid nicad memory, and is practiced
religiously by racers, whose cars can draw sustained
currents of 20-30 amps from a 7.2 volt pack (six sub-C cells).
I recognize that this is at the opposite end of the scale from
typical current draws in a battery-biased tube circuit, but the
charge/discharge cycling presumably still occurs.
Recently nickel-metal-hydride cells have begun appearing
on the hobby market; these cells supposedly do not have a
memory problem, have a higher power density that nicads
and last longer. If anyone wants a mail-order source for
NiMH cells, please post me.
=========================================================================
From: Paulo Avelino <avelino@ibm.net>
Subject: Re: Battery Bias -NiMH cells & (no) thanks for the memory
Date: Fri, 02 Oct 1998 19:48:41 -0300
Source: Sound Digest Archive v01.n438
Would love to have addresses for any kind of battery supplier. Just
bought a Japanese amplifier that runs on batteries (the Final Music 6 -
see HiFiNews Oct 98 pg. 79). Actually 36 C-cells that are supposed to
last for one and a half months with two hour daily sessions. I might
just have bought the radio controlled cars anxiety.
trs@carlsmith.com wrote:
> Those of us that race radio-controlled cars as a hobby
> (actually, I only do it for my kid. . . ) know that there are
> some very sophisticated low-impedance "sub-C" nicad cells
> available now at low prices, but all generally remain plagued
> by "memory" - the tendency of a nicad cell, when repeatedly
> discharged only partially, to act as if its capacity is limited to
> the range between full charge and that partial discharge
> point. Regular, complete discharge ("cycling") is believed to
> be important to avoid nicad memory, and is practiced
> religiously by racers, whose cars can draw sustained
> currents of 20-30 amps from a 7.2 volt pack (six sub-C cells).
> I recognize that this is at the opposite end of the scale from
> typical current draws in a battery-biased tube circuit, but the
> charge/discharge cycling presumably still occurs.
> Recently nickel-metal-hydride cells have begun appearing
> on the hobby market; these cells supposedly do not have a
> memory problem, have a higher power density that nicads
> and last longer. If anyone wants a mail-order source for
> NiMH cells, please post me.
=========================================================================
From: Kurt Steffensen <solvin-aurum@get2net.dk>
Subject: Re: Battery Bias -NiMH cells & (no) thanks for the memory
Date: Fri, 02 Oct 1998 23:40:47 +0200
Source: Sound Digest Archive v01.n438
Gentlemen.
For what it is worth, I have used NiMH batteries as Anode supply
in a MC amplifier.
I choosed them for two reasons:
They are supposed to care little about the charging/discharging cycles.
They were those that had the lowest noise in this circuit of mine.
I have made less than 20 pcs, but they are all still out there,
working with no problems.
And the users do not care at all, about how to charge them.
I told them that was no problem. (So says the factory)
I sold the first pieces 3-4 years ago.
- - Sincerely Kurt Steffensen
=========================================================================
From: Dan Kerl <dlkerl@ro.com>
Subject: Re: Battery Bias -NiMH cells & (no) thanks for the memory
Date: Mon, 05 Oct 1998 10:04:35 -0500
Source: Sound Digest Archive v01.n441
Paulo Avelino wrote:
>
> Would love to have addresses for any kind of battery supplier.
Here's a few from flyers that I picked up at a hamfest last
August. Mainly dealing in battery packs, they also appear to
have individual cells available. I've had no experience with
these outfits, so YMMV:
E.H Yost & Co.
2211 D Parview Rd.
Middleton WI 53562
phone: 608 831 3443
fax: 608 831 1082
ehyost@midplains.net
Battery-Tech inc.
800 South Broadway
Hicksville NY 11801-5017
phone: 516-496-9520
fax: 516-496-9523
The Battery Station, inc.
620 N. Court
Ottumwa Iowa 52501
phone: 515-683-7621
fax: 515-683-7631
info@batterystation.com
http://www.batterystation.com
HTH
- --
Dan Kerl
dlkerl@ro.com
=========================================================================
From: trs@carlsmith.com
Subject: Re: Battery Bias -NiMH cells & (no) thanks for the memory -Reply
Date: Tue, 6 Oct 1998 11:31:03 -1000
Source: Sound Digest Archive v01.n443
Here's the info on a source for NiMH batteries:
Source: Tower Hobbies [http://www.towerhobbies.com/]
P.O. Box 9078
Champaign, IL 61826-9078
1-800-637-4989
Product: HydriMax Nickel-Metal Hydride Batteries
Examples (individual cells - they have packs too):
Stock No. Description Price
HCAP6320 1.2 AH 1.2 volt w/o tab $5.49/cell
HCAP6321 1.2 AH 1.2 volt w/tab $5.79/cell
HCAP6341 1.8 AH 1.2 volt w/tab $7.49/cell
Regards, Tom Sylvester trs@carlsmith.com
=========================================================================
From: David Home <tubehead@vcn.bc.ca>
Subject: Battery bias question
Date: Sat, 7 Feb 1998 23:19:14 -0800 (PST)
Source: Sound Digest Archive v01.n185
I'm trying out a simple 6SN7 plate follower which I have working at the
right current with -2.4V bias. Why not try out battery bias(2Cs in
series) in the cathode?, I say. Question: As the battery itself has
next to nothing impedance, could I connect both section cathodes
together off of the same battery? Each section is in a diiferent
channel. Save some valuable realestate in my enclosure if it works.
Will there be cross-talk between channels?
Regards, David
=========================================================================
From: MHuber@t-online.de (Manfred Huber)
Subject: Re: Battery bias question
Date: Sun, 08 Feb 98 10:16:19 -0100
Source: Sound Digest Archive v01.n186
David,
>Question: As the battery itself has next to nothing impedance,
>could I connect both section cathodes together off of the same battery?
This is what I'm doing in my preamp. No problem with crosstalk. I had to
go with one shared NiCd battery for both channels because I'm using a 3A5 dual
DHT which shares a common filament pin between both sections.
Regards
Manfred
- ------------------
Manfred Huber
MHuber@t-online.de
- ------------------
=========================================================================
From: MHuber@t-online.de (Manfred Huber)
Subject: Re: Battery bias question
Date: Wed, 22 Apr 1998 15:56:16 +0100
Source: Sound Digest Archive v01.n259
David,
>Question: As the battery itself has next to nothing impedance, could I connect both section cathode
s
>together off of the same battery?
I do this in my DHT-preamp and experienced no problems.
>Will there be cross-talk between channels?
I have som crosstalk from the switches and attenuators but not from
the common NiCd cells.
Regards
Manfred
- ------------------
Manfred Huber
MHuber@t-online.de
- ------------------
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Battery Info and Charging needed
Date: Mon, 8 Sep 97 09:46:07 -0000
Source: Sound Digest Archive v01.n015
Gang,
If anyone knows were I can get info on battery charging I would
appreciate it? Also anyone know of standard cells for LI-Ion types?
Thanks in advance!
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "Peter Clark" <ReverendClark@worldnet.att.net>
Subject: Battery Powered or LV Amps
Date: Sun, 13 Sep 1998 18:52:12 -0700
Source: Sound Digest Archive v01.n422
I came across some low volt filament output tubes the other day which I
just couldn't resist. I was put in mind of an article in Glass Audio #3,
1998, "Try Battery Tubes" which was intriguing. The author cited "most
liquid and natural sounding," which will get my attention every time.
I have zero experience with battery power. Do any listees have any
resources for this endeavor and probably more importantly, comments about
the overall desirability of even trying this? My speakers are plenty
efficient, so very low output power hold no terrors... TIA
Peter Clark
=========================================================================
From: jc morrison <jcm@eclipse.net>
Subject: Re: Battery powered solid-state preamp...
Date: Tue, 26 May 1998 00:28:47 -0700
Source: Sound Digest Archive v01.n293
peter sikking wrote:
>
> Hi jc.
>
> Sorry to disturb you by writing you directly, I hope you have time to
> answer my quetion.
>
> On the Joenet you wrote that you and dick sequerra `built a battery
> powered solid-state preamp (no power supply capacitors at all).'
> The recent discussion on powering DAC's from batteries has got me
> thinking again on powering everything SS in my set-up from batteries.
>
> Now some people have told me that batteries are _slow_, but you seem
> to have found a way of avoiding local decoupling capacitors. Can you
> disclose what the trick is?
>
> PS: If you think that your answer is going to be interresting for other
> Joester, please feel free to crosspost to the joenet.
>
> Thanks,
>
> --Peter
>
the impedance of batteries, and here we are talking about lead acid or
"gel cell" (still lead acid), is super low, but still amounts to
something in the vicinity of .05 ohms per 2 volt 4 AmpHour cell
(standard). a 6 volt battery will series connect 3 cells, so the total
average z will be 3 x .05 ohms, or .15 ohms. not bad! but series connect
three 6 volt batteries and you now have .45 ohms and so on. one obvious
solution is to parallel cells, or use larger AH rated batteries. slow?
not slower than a choke input or pi filtered unregulated supply of any
type (*MUCH* higher impedance). smaller batteries will have to be
bypassed with a 1 uf film cap because of the rise in impedance at higher
frequencies (of demand). hope this helps.
jc
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: Battery powered solid-state preamp...
Date: Wed, 27 May 1998 08:44:34 +0200
Source: Sound Digest Archive v01.n293
>the impedance of batteries, and here we are talking about lead acid or
>"gel cell" (still lead acid), is super low, but still amounts to
>something in the vicinity of .05 ohms per 2 volt 4 AmpHour cell
>(standard). a 6 volt battery will series connect 3 cells, so the total
>average z will be 3 x .05 ohms, or .15 ohms. not bad! but series connect
>three 6 volt batteries and you now have .45 ohms and so on. one obvious
>solution is to parallel cells, or use larger AH rated batteries. slow?
>not slower than a choke input or pi filtered unregulated supply of any
>type (*MUCH* higher impedance). smaller batteries will have to be
>bypassed with a 1 uf film cap because of the rise in impedance at higher
>frequencies (of demand). hope this helps.
>jc
The series inductance detrmines the RF cut of. That means that wiring from
the battery should be lo-inducatnce (screened caox....)
The chemical process is a slow one, to my opinion
All depends again as well on the current demand of the circuit
Remember ECL coupled logic, beautifully balanced
But yes, balance requires phase splitting and.....
What a hobby
Guido
=========================================================================
From: Simon Busbridge <S.C.Busbridge@bton.ac.uk>
Subject: Battery Vavles in Audio
Date: Wed, 5 Nov 1997 07:54:30 +0000 (GMT)
Source: Sound Digest Archive v01.n100
Hello All,
I wonder if someone could give me some advice as to the use of battery
valves in audio. I know that Mattijs uses a 1G4 in his system, but I
have always thought that the 1.4 V valves generally have a low g and high
ra, and tend to be microphonic, but I'd be interested to hear from anyone
who has used them and the sonic benefits, if any. The "peanut" valves
seem to be correctly biassed at vg = 0 V, which may give a grid current
problem. On the other had perhaps they are quiter than mains valves?
If I had to guess about their sonics (dangerous!) then I would say that
perhaps their presentation would be very clean, but maybe thin. As a
friend of mine once put it, lacking "balls". But please correct me if
I've got it all wrong.
The 2 V valves have higher g and lower ra, but are much older and
therefore rarer.
TIA
Simon
Dr Simon Busbridge
University of Brighton
Lewes Road
Moulsecoomb
Brighton BN2 4GJ
UNITED KINGDOM
Tel: 0044 (0)1273 642542
Fax: 0044 (0)1273 642327
e-mail: s.c.busbridge@bton.ac.uk
"..biology is what you do when you don't have the maths for real
science.." (sliders)
=========================================================================
From: "Johannes S. Chiu" <jschiu@ctr.columbia.edu>
Subject: BAT Volume control: How they may have done it
Date: Sat, 4 Apr 1998 00:31:03 -0500 (EST)
Source: Sound Digest Archive v01.n244
Hi all,
I looked at the BAT web site and studied the CS3310
data sheet. I think this is how they COULD have done it.
Pure speculation though, but it would reflect everything
in the marketing literature.
Take the CS3310, a Vishay 90K resistor, and a 6922 diff. amp
stage. Put the resistor in series with the CS3310 input, like a grid
stop resistor. Take the CS3310 input to the diff. amp + terminal,
take the output of the CS3310 to the - terminal of the
diff. amp. Since the diff. amp take a differential signal, the volume
is increased not by increasing the + terminal voltage, but by reducing
the - terminal voltage. If one considers the + terminal as the
"signal" path, the it would be input->90k->diff. amp->output. Ok, I'm
pushing it, but it is possible that some would market it in this way.
This scheme does have a little advantage than cascading the CS3310
and diff. amp. In this scheme, the IC is basically out of the circuit
at max. volume, since this occurs when CS3310 output is zero. The CS3310
will have more contribution at low volume levels, which makes it distortion
less audible. Also note that input impedance is constant. Someone
should ask BAT if the input impedance changes, which would be another proof
whether they use this scheme or not. Of course, since the amp is all
balanced, the signal mixing scheme is more complicated. Maybe this is
why they use ten tubes, while at the smae time claiming pure signal paths?
Perhaps someone can think of a scheme where the output of the CS3310
output is somehow directly connected to its own input, so that it
shorts out part of the shunt.
- --
Johannes S. Chiu
jschiu@ctr.columbia.edu
Columbia University
New York City
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: BAT Volume control: How they may have done it
Date: Mon, 6 Apr 98 09:46:38 -0500
Source: Sound Digest Archive v01.n246
Johannes,
>I looked at the BAT web site and studied the CS3310
>data sheet. I think this is how they COULD have done it.
>Pure speculation though, but it would reflect everything
>in the marketing literature.
Actually you may have something there, but what about the differential
inputs on the preamp? I think they are using this as a buzz word as they
do their VK60 which they claim to be SE but it is really an autoformer
OTL.
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: Rick Francis <rfranci@uoft03.UTOLEDO.EDU>
Subject: Bay Area Tube Enthusiasts Weekend Feb. 6 & 7, 1998 (fwd)
Date: Sun, 23 Nov 1997 21:56:17 -0500 (EST)
Source: Sound Digest Archive v01.n118
Sharing information here...
Rick Francis, rfranci@uoft03.utoledo.edu
- ---------- Forwarded message ----------
From: Charlie Kittleson <triode@vacuumtube.com>
Newsgroups: rec.audio.tubes
Subject: Bay Area Tube Enthusiasts Weekend Feb. 6 & 7, 1998
Vacuum Tube Valley is sponsoring an all-tube weekend in the Bay Area
on February 6 & 7, 1998 with several events including two swap meets,
a free seminar featuring Dr. Bruce Edgar (loudspeaker designer), VTV
Tube School for Hi Fi and Guitar Amps, plus a vacuum tube mini-trade
show.
For more information and a look at our latest FAQ Bulletin
go to: www.vacuumtube.com
Thanks
Charlie Kittleson
Editor, VTV
- ------- End of Forwarded Message
=========================================================================
From: Joseph Lowe <jlowe@cdc.net>
Subject: BBC Hammers Sony/Phillips "super CD"
Date: Wed, 18 Feb 1998 15:42:22 -0500 (EST)
Source: Sound Digest Archive v01.n196
Today's BBC Real Audio Business report gave a very negative review to the
new Sony/Phillips "Super CD" based on DVD. The demo was held at Abby road
studios. Hear the review for yourself at:
http://www.bbc.co.uk/worldservice/worldbusinessreport/
The review is the second or third story in the report.
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: BBC sound: JBL (humorous)
Date: Wed, 02 Dec 1998 13:22:01
Source: Sound Digest Archive v01.n514
A 08:51 AM 12/2/98 -0500, Mark Donen a écrit :
>Press Release:
>
>JBL today rejected a generous offer of a free redesign program. The
>proposed program was offered by Mr. Olson. "How could we do anything
>else?" JBL spokesmen explained. "Our monitors can handle produce a
>continuous 120 dB with very high sensitivity. We found the prototypes
>Mr. Olson offered us blew up almost immediately with anemic bass output.
>Our products serve the needs of our customers. Mr. Olson's speakers are
>simply addressed to a different clientele". Mr. Olson offered the
>following remark: "The BBC have determined in objective research that no
>monitor loudspeaker shall be capable of more than 95 dB continuous
>maximum sound pressure or have low frequency output below 60 cycles. JBL
>would benefit from recognizing this truth."
As the owner of two pairs of Quad 57s, KEF 104s, and KEF 103s, I feel like
I ought to take your little diatribes personally. The U.K. sound works
exceptionally well for classical music in small-to-medium sized rooms, not
in anechoic chambers. I listen to classical music in a condo flat of
moderate dimensions. I biamplify my Quads, using puny, anemic little Kef
B-139s as subs, and my hi-fi rig can reproduce Bach organ fugues with a
realism of timbre that is astonishing. I don't presently have double Quads
set up, despite owning four of them, nor do I feel the need at the moment,
as the SPLs obtainable with this system are ample for my musical tastes.
If one wants more bass from the British sound, one adds subwoofers. When
BBC-type speakers fail to produce adequate SPLs in a given room, one adds
more of them. Surely this is a more musical solution than bringing public
address equipment into one's home.
Cheers,
Auntie
=========================================================================
From: bill gardner <wg44929@navix.net>
Subject: Re: BBC sound: JBL (humorous)
Date: Wed, 02 Dec 1998 21:13:32 -0600
Source: Sound Digest Archive v01.n515
At 01:22 PM 12/2/98, David B. Klein wrote:
>A 08:51 AM 12/2/98 -0500, Mark Donen a écrit :
>>Press Release:
."
>>If one wants more bass from the British sound, one adds subwoofers. When
>BBC-type speakers fail to produce adequate SPLs in a given room, one adds
>more of them. Surely this is a more musical solution than bringing public
>address equipment into one's home.
>
>Cheers,
>
>Auntie
>
Tell this to Jean Hiraga ....... perhaps he's not aware that altec stuff
can't be tamed ..........
best to you also Bill Gardner
=========================================================================
From: "Johari Yip" <hfyip@pacific.net.sg>
Subject: Re: BBC sound: JBL (humorous)
Date: Thu, 3 Dec 1998 15:22:43 +0800
Source: Sound Digest Archive v01.n516
- ----------
From: Bart Shepherd <bart.shepherd@ttm.com.sg>
To: David B. Klein <dklein@microtec.net>; Mark Donen
<soledadd@worldnet.att.net>; Joenet <sound@deliverator.io.com>; bill
gardner <wg44929@navix.net>
Subject: Re: BBC sound: JBL (humorous)
Date: Thursday, December 03, 1998 1:24 PM
The main reason a lot of professional equipment is not brought into homes
is
cost. Most of this equipment is far superior to so called "British" Hi-Fi.
That's why they're called "Pro gears".
My recollection of the "British" sound is an over-polite (read compressed
and frequency limited) sound with rolled off highs and a plummy or puddeny
mid-bass plus rolled off lower bass. This is exemplified by the myriad of
ported two way boxes with 20 cm drivers. One rolls the top when one has no
bottom. ( I include highly touted but ultimately disappointing Spendors and
Celestions here and even Quads - transparency notwithstanding (the later
good mid-range panel only - not puddeny - if you can stand the lack of
dynamic range)).
In general, yes.
Dont get me wrong, I am not anti British but if you want British give me a
38 cm Tannoy Dual Concentric "PA" driver any day. Those with tiny rooms can
only read and weep.
Don't forget the highly criticized Lowther, they are not your everyday
"British" speakers. Not neccessary to have big rooms.
Not knocking BBC type monitors either but wasn't intended use of some of
the
most famous a near field voice monitor! Exactly what they are suited to.
Agree with you here. Voicing is OK, Music reproduction? Not really.
Bart (donning asbestos suit) :-0
Cheers,
Johari
=========================================================================
From: "Bart Shepherd" <bart.shepherd@ttm.com.sg>
Subject: Re: BBC sound: JBL (humorous)
Date: Thu, 3 Dec 1998 16:24:01 +1100
Source: Sound Digest Archive v01.n516
The main reason a lot of professional equipment is not brought into homes is
cost. Most of this equipment is far superior to so called "British" Hi-Fi.
My recollection of the "British" sound is an over-polite (read compressed
and frequency limited) sound with rolled off highs and a plummy or puddeny
mid-bass plus rolled off lower bass. This is exemplified by the myriad of
ported two way boxes with 20 cm drivers. One rolls the top when one has no
bottom. ( I include highly touted but ultimately disappointing Spendors and
Celestions here and even Quads - transparency notwithstanding (the later
good mid-range panel only - not puddeny - if you can stand the lack of
dynamic range)).
Dont get me wrong, I am not anti British but if you want British give me a
38 cm Tannoy Dual Concentric "PA" driver any day. Those with tiny rooms can
only read and weep.
Not knocking BBC type monitors either but wasn't intended use of some of the
most famous a near field voice monitor! Exactly what they are suited to.
Bart (donning asbestos suit) :-0
- -----Original Message-----
From: bill gardner <wg44929@navix.net>
To: David B. Klein <dklein@microtec.net>; Mark Donen
<soledadd@worldnet.att.net>; Joenet <sound@deliverator.io.com>
Date: Thursday, December 03, 1998 3:15 PM
Subject: Re: BBC sound: JBL (humorous)
>At 01:22 PM 12/2/98, David B. Klein wrote:
>>A 08:51 AM 12/2/98 -0500, Mark Donen a écrit :
>>>Press Release:
>."
>
>>>If one wants more bass from the British sound, one adds subwoofers. When
>>BBC-type speakers fail to produce adequate SPLs in a given room, one adds
>>more of them. Surely this is a more musical solution than bringing public
>>address equipment into one's home.
>>
>>Cheers,
>>
>>Auntie
>>
>Tell this to Jean Hiraga ....... perhaps he's not aware that altec stuff
>can't be tamed ..........
> best to you also Bill Gardner
=========================================================================
From: wmeckle@primenet.com (William Eckle)
Subject: BBQ
Date: Sat, 20 Jun 1998 19:48:36 GMT
Source: Sound Digest Archive v01.n317
From: Thomas Danley
Subject: BBQ in 1 week
Hi All June 20th
Well were one week away from the BBQ so I thought I would try to do a
couple things related to preparations.
First, I need to know about how many of you are comming.
I have invited some additional speaker industry and reviewer types
so there should be even more/better discussions than last year but since
there are several different companies represented lets keep it to DIY
rather than buisness stuff.
I have a BBQ pit and I'll fill the cooler with ice.
You all should bring some picnic type food and/or beverages for a "pot
luck" sort of thing. That was the arangement Last year and that seemed
to work well, several people brought wonderfull stuff like ribs and
killer cheese cake. It worked well as after listening to music outside
for a while you get hungry.
Several people have offered to give me money for the trouble but I
would rather you bring things to share with everyone.
Some of you are comming in on the train or airplane so let me or John
Halliburton know your schedule and we will try to arrange rides.
Several people have asked where they should stay. If you have a tent,
you could camp in the back yard or you could stay at a motel. The
closest one is the Shoreline Lodge at 3330 Skokie vally rd, Highland
Park Il. There are also Marriot hotels fairly close in
Deerfield and Lincolnshire, there # are 847-405-9666 and 847-634-0100.
Like last time, I will have the TEF measuring system set up with a
printer so if you have a speaker you want measured bring it although I
don't want to do measurments ALL day. Also I hope to have a Hyperception
DSP demo set up (assuming that all comes together this week)
Seperate from that will be a listening area in the back yard, I'll
have one Contra-bass open to look at and 4 to listen too.
Brad from ServoDrive will likely be there too.
Several people are bringing speakers to listen to and I will have the
full range rotary drivers out again.
Bring a couple of your BEST sounding CD's. If you are driving up and
have have a couple lawn chairs and room in the car, bring those too.
I figure we could start at 9:30-10:00 in the morning and go until about
10 or 11pm. One thing that is cool is listening to Dark side of the Moon
at night outside.
We can also fire up some antique engines if theres interest although the
biggest one needs a little work (a 620 cubic inch one cylinder diesel
that weighs 5800 lb and makes 15hp) .
So far as getting here, here is 2345 Shady Lane Highland Park IL.
I'm not great with maps but leave it to the internet to solve the
problem. Go to mapquest at
http://www.mapquest.com/
and get a personalised driving map. Look for loudspeaker "clues" at the
end of the driveway.
Be sure to let me know your plans.
I hope every one has a good time,it should be fun again, see you there.
Tom Danley
Intersonics Technology Corp
*************************Comming Soon************************
2nd annual Chi-area DIY BBQ June 27th 1998, Highland Park IL
=========================================================================
From: wmeckle@primenet.com (William Eckle)
Subject: BBQ
Date: Tue, 23 Jun 1998 21:51:28 GMT
Source: Sound Digest Archive v01.n319
>From Tom@ppci.com Tue Jun 23 14:15:59 1998
Reply-To: Tom@ppci.com
Hi all
The 2nd DIY Bass BBQ Saturday the 27th and the weather looks better than
last year (except it is going to be hot) to whatever extent you can
trust the weather guys.
Ron Peterson has again kinly offered to help with transportation from
Airport/train etc. He can be reached until thurs afternoon at
rpeterse@wirenut.com and then on at rpeterse@wwa.com
John Halliburton is bringing over a couple of Webbers so we won't have
the grill space problem of last year. Also Watts will not be a problem
this year, I have a Crown Delta omega (2KW) waiting for the 4 Contra's
Brad is bringing.
There will be some people other than Bass-lister's this time, Tom
Nousain, Mike Sims and a couple of there Prarie States Audio
Construction Society (PSACS) will be there, Earl Geddes is comming, Dick
Olsher can't come this time but will be at the next one, several others
are pending.
Several people from the "Joe List" are also comming as there is
aparently some degree of cross posting.
Ron Erickson brought some killer homemade cheese cake last time
that was supurb and has offered to bring them again this year.
I don't know what others are bringing but remember it is "pot luck" so
bring some thing to pass.
I was trying to have a second mini contra (.7 cu/ft) up and running,
It won't be but you can see the guts etc along with a regular unit.
Also, I will set up one of the Acoustic Levitators I used to work on.
These have a sound source which produces up to about 168 dB at 22KHZ
which is sufficient to "levitate" a small object (<1/4 wl across) in mid
air. Several (6) of these sources can be arrayed to make a 3 axis
levitator which can produce about 172 dB at the center, which is enough
intensity to light a cigarette with acoustic friction or position an IR
laser heated molten glob of ceramic at 2500 deg C..
Saturday we might try to levitate an ant or sow bug instead.
If you are comming and havn't let me know, please do so.
Beast Regards,
Be sure to let me know your plans.
I hope every one has a good time,it should be fun again, see you there.
Tom Danley
Intersonics Technology Corp
*************************Comming Soon************************
2nd annual Chi-area DIY BBQ June 27th 1998, Highland Park IL
=========================================================================
From: Daniel Normolle <monk@umich.edu>
Subject: BBQ
Date: Wed, 24 Jun 1998 08:45:46 -0400
Source: Sound Digest Archive v01.n319
You guys attending the BBQ need to be aware of the most
impressive grill-lighter on the planet:
http://ghg.ecn.purdue.edu/
George can get forty pounds of charcoal ready to cook in
3 seconds. See how. dpn
=========================================================================
From: William Eckle <wmeckle@primenet.com>
Subject: BBQ
Date: Thu, 02 Jul 1998 04:48:51 -0700
Source: Sound Digest Archive v01.n330
Understand a couple Joeneters went to Tom Danley's BBQ, how about a report ?
<bold><underline>-=<color><param>ffff,0000,0000</param>Bill
Eckle</color>=-
</underline></bold>wmeckle@primenet.com
<italic><color><param>0000,0000,ffff</param> Phoenix, Arizona
USA</color></italic>
=========================================================================
From: Thomas Danley <Tom@ppci.com>
Subject: Re: BBQ
Date: Thu, 02 Jul 1998 09:17:23 -0500
Source: Sound Digest Archive v01.n330
William Eckle wrote:
>
> Understand a couple Joeneters went to Tom Danley's BBQ, how about a
> report ?
>
> -=Bill Eckle=-
> wmeckle@primenet.com
> Phoenix, Arizona USA
Hi
Well I had sort of a summary on the diy-list so I'll send it here too,
I'm sure I have left things out though. Matbe Tom B. can "fill in" a
bit.
> Hi all
>
> I wanted to thank the members who made it to the 2nd Speaker BBQ on the
> 27th. Attendance was about 60-70 people during the course of the day.
> This year, in addition to list members, I had invited some additional
> people. Mike Sims, Tom Parazella and several other of
> Tom Nousain's group came (Tom had a last second problem and couldn't
> make it) as well as a couple people from the "joe-list".
> Also, people from ServoDrive, Jensen, Eminance, AIT and other speaker
> companies were there as well as Earl Geddes and his family.
> A good mix, all speaker people :-)
> The weather could have been worse, but it could have been better too, it
> was very hot, like the "dog days of August" but humid too.
> Fortunatly my neighbor/friend/ISP Bill brought over 3 fans for personal
> cooling. ServoDrive provided 4 Contra's for bass which acording to one
> neighbor was sufficient low end to be felt about 500 feet away, inside,
> with a room airconditioner running full blast (must have been the radial
> aircraft recording that Mike Sims was playing). Good thing she is used
> to being my neighbor :-) Among the things people brought, Doug S brought
> his "rear channels" a pair of good sized ribbons to hear and Nick M
> brought a pile of driver parts to look at. Charlie R, my boss brought
> over an acoustic levitator to float things, I miss working on that
> stuff. I had the rotary full range drivers I had made last year > operating most of the time. The
y operate from 75HZ to 25KHZ with out a > crossover or eq etc.
>
> Like last year the food was great, Brian B brought some really good
> (from Boston) Boston clam chowder, Ron brought his killer home made
> cheese cake, Earl brought a great fruit salad and a fellow who's name I
> forget brought some Very tastey and very hot chicken wings..
> John H. brought over a pair of Webbers to cook in which easily handled
> the crowd. The food was great, thank you all.
>
> I have to apoligize to the people that wanted to measure drivers, the
> day just flew by and if I was smart I would have gone inside where the
> TEF machine (and AIR CONDITIONING) was. Next time I am going to get some
> additional help so I don't have to make so many trips to the kitchen
> etc. too.
>
> I'm sure I am leaving things out, some of the list-ers that went can
> better fill in more of the details.
> Best Regards,
>
> Tom Danley
> ITC
>
=========================================================================
From: Martin Needleman <mrndlmn@beast.toad.net>
Subject: Beaming Quads (was Quads, Dynamics.etc.)
Date: Tue, 3 Feb 1998 10:31:22 -0500 (EST)
Source: Sound Digest Archive v01.n180
On Mon, 2 Feb 1998, Mark K. Long wrote:
<===================== giant snip ======================>
> a TAD compression driver. Sure would be nice to solve the high freq
> beaming of the Quad.
>
O.K. Mark (and others) it's time to pass on the secret of non-beaming
Quads. Just rotate the firescreens 90 degrees. From top to bottom you then
have horizontally oriented panels in the following order - Bass, Midrange,
Treble, Midrange, Bass. This orientation pretty well eliminates the
horizontal beaming problem and introduces a couple of new problems which,
fortunately, can generally (not always!) be solved by careful attention to
speaker positioning within the room.
Experiment. Report results. YMMV
mrn
=========================================================================
From: Guido Tent <gtent@ehv.sc.philips.com>
Subject: Re: beating EMI (?)
Date: Fri, 3 Oct 1997 10:11:38 +0200
Source: Sound Digest Archive v01.n055
Peter,
At 17:16 3-10-97 +1000, Peter Allen wrote:
>Guido,
>I saw an article in HiFi News
I did not yet, 'll have a look this weekend
>this year that looked convincing to me, but
>then my judgment is always whispy. In the ongoing flame wars, I always
>think the person who wrote last won the argument.
That's not always true
>Anyway, the article gave a convincing (to me) argument that each piece of
>hifi equipment (because of their power supply topping up for only part of
>the ac cycle) injects noise back into the power line.
That is correct
>He then gave a solution: make an ac mains cable from Kimber cable, the
>braided configuration. Of course this could be dangerous if not done
>competently, but here we will assume it's safe.
OK, why kimber ?
>Does this make sense to you?
>Where would it have most effect?
As long as their is copper between equipment, the problem remains,
regardless of the quality of the cables. The problems are due to common mode
currents, and no mains cable changes that whatever material you use
As long as equipment is interconnected, and in the vicinity of each other,
the problmens remain
>If we have separate mains circuits at home, how should components best be
>connected? ...keep everything digital together, for example.
Mmmh. There are other cables inbetween your equipment, so the effect of
separating mainscables will be very small
>I ask these things knowing it's your specialty, and that it could be a
>matter of national importance. OK maybe just to all the list members.
Equipment should be made intrinsically good, with EMC in mind. those who
tell you that cables or few ferrites solve your problem do not know what
they are talking about
I am writing an article in a Dutch magazine about this subject. Once there
is time, I'll make a translation, publish it in SP or whatever
>Regards to the Koreans, but it's not compulsory for foreigners to eat Kim
>Chee for breakfast.
Thanks for the advice, but what is Kim Chee ? I am in a Hotel, I suppose
they have "european" breakfast too
Guido
>-peter
>_____________________________________________________________
>Peter Allen ptrallen@melbpc.org.au ( 8*{)
>Editor, Melbourne Audio Club http://www.vicnet.net.au/~macinc
> ask for a free e-copy of our magazine FAX +61 3 9431-2044
>
>
>
" 640K ought to be enough for anybody" , Bill Gates, 1981
Disclaimer: The opinions expressed herin are my personal ones and do not in
any way reflect opinions or policies of my employer.
Guido Tent
Engineer Electro Magnetic Compatibility
Philips Semiconductors Systems Laboratory Eindhoven (PS-SLE)
Building BE303, (Hurksestraat 19)
P.O.Box 218, 5600MD Eindhoven, The Netherlands
Phone: +31-40-27 24553
fax : +31-40-27 22764
- - Let's make things better ! -
E-mail: guido.tent@ehv. sc.philips.com
Seri : gtent@nlsce1
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: becomming long - Re: 5687 linestage - now WOT
Date: Sun, 03 Jan 1999 14:21:54 +0100
Source: Sound Digest Archive v01.n555
dear Bill, others,
To maintain insight, I copied all text. Please forgive me.
I could only agree with your (Bills') reply, but would like to add:
1-CF - The cathode only "follows" if:
A-the current through the CF tube is held constant (independant of signal)
B-the voltage across the CF tube is held constant (independant of signal)
I implemented this a year gao in my 300b and I was surprised. At first I
had a CF in the system that was transparant. Please refer to Allen Wright,
for example. Current sources and cascoding do the job.
2-Harmonic cancelation
I do not agree with this principle. Two cascaded inverting gain stages give
a mess of harmonics (I both calculated and measured on this subject for my
graduation, years ago), unless the first has significant lower distortion
than the latter. If this is the case the latter defines the distortion, and
as such no cancelation is present. I found this solution sound better.
Anyhow, we are not yet finished and keep Bills' experiment in mind
Guido
At 00:49 3-1-99 -0700, PEARL Cust Serv wrote:
> Johari Yip wrote:
>>Hi everyone,
>>
>>Thanks Guido, you've listed a whole list of "pros" to why IT coupling is,
>>in fact, far superior to R-C coupling in amps but at a much higher cost.
>>Now, having said all the advantages of IT coupling, Am I correct to say
>>that there would be further improvement if the linestage is also OPTX
>>coupled?
>>On a different note, I know with IT coupling, we can bias the output tube
>>for Class A2 operation for some transmitter tubes like the 211, 845 and the
>>recent SV572 series of tubes. What's the advantage of IT coupling in Class
>>A2 operation here as compared to, say, cathode follower coupled from a
>>power tube like 6AS7, triode-wired EL34, 6L6 etc a la "AN Ongaku"?
>>Guido or anyone?
>>
>>Thanks in advance,
>>Johari
>======================
>
> Guido wrote:
>>> Joes,
>>>
>>> Since I heard my first IT coupled amp I never want R-C coupling anymore:
>>>
>>> The technical reasons and advantages of iron
>>>
>>> 1-no series coupling cap
>>> 2-no secondary load of the IT necessary so:
>>> 3-no current through the driving tube
>>> 4-no current through the supply (except dc)
>>> 5-no waste of audio energy since transformers do not absorb
>>> 6-ease of fixed biasing to next stage, eliminating another (cathode)cap
>>> 7-lower supply voltages, or:
>>> 8-more voltage swing at even lower than original supply (remember, no
>>waste)
>>> 9-less distortion (I have 90 Vrms with only 0,2% thd)
>>>
>>> You need a good IT though
>>>
>>> regards,
>>> =
>>> Guido
>>>
>===================
>
>Dear Johari:
> Taking up first the question you posed in your last paragraph: assuming
>that you inquire about Class A2 single-ended operation, it's my thought that
>an IT used to anode load the driver stage would not perform as well on the
>test bench as a resistively loaded cathode follower. I've not yet built
>either of these stages and so cannot begin to comment on sonics.
>
> Before getting into this however it is useful to recall a few of things
>about coupling transformers:
> 1 - For the vast majority of ITs designed for power amp use, there is no
>need to
> wind anything other than a 1:1 ratio. If the IT is replacing a load
>resistor
> and the original B+ is maintained (and the driver tube can handle
>such B+/
> dissipation and is very linear) then the available output rises
> by 6dB nearly enough...
> 2 - Because a 1:1 ratio is satisfactory, it is both possible and
>practical to
> bifilarly wind the primary and secondary. This has several
>advantages:
> a - VERY tight inductive coupling
> b - NO >> effective << capacitance primary-to-secondary until the
>leakage
> reactance begins to cause the secondary voltage to roll off.
> c - easy construction, almost, there is a trick NEEDED here that
>I'll leave to
> your discovery
> 3 - 'b' above depends crucially upon adjacent ends of the pri. & sec.
>being
> connected "earthy" and "swinging".
>
> Theoretically then, the matter is that with an increasingly positive
>drive on the output tube's control grid, an increasing electron flow from
>that grid must be "sunk" by the driving stage.
> In the CF case, the cathode's voltage is VERY closely "following" (hence
>the name) the increasingly positive voltage on the control grid. The driver
>tube is being "turned on", so to speak, with the result that it's Rp
>diminishes and this enables the tube to handle the demand that it "sink"
>electron flow from the subsequent, positively driven control grid. Remember
>that the CF stage is non-inverting...
> The anode loaded IT stage is inverting so it's grid must be driven more
>negative, turning the tube "off" and increasing it's Rp. by the action of
>the transformer, this increasing Rp appears effectively in series with the
>increasing conductance (decreasing resistance) of the positively driven
>output control grid. The result is a decreased ability to sink electron flow
>from the said grid and the outcome will be dynamic compression...
> In a push-pull stage, this outcome is ideal as it fosters soft clipping,
>in an SE stage, it's a mess...
> The "obvious" solution might be to reverse the connection of either the
>primary OR the secondary but this will completely blow off the very
>agreeable condition 'b' above. I don't think I'd follow this route.
> It seems more sensible to choke load a voltage amp and cap couple it
>into a self-biased CF with the IT connected between the series,
>bias-generating resistor and ground. With 100k or less from the CF's control
>grid to the junction of the IT and resistor, it's input impedance will be
>enormous so a very small Jensen, copper-foil oiler could be used and the
>driver stage would run essentially constant current...
> Then again, I haven't built this although I'm about to...
> There are few more things I want to say, but somehow it got to be
>midnight!! ...
> How'd THAT happen??
>
>
> Happy Trails,
> Bill Perkins, PEARL Inc.
> 2528 19 St. S.W., Calgary, Ab.,
> Canada T2T 4X3
> Ph. 1 403 244 4434 Fx. 1 403 244 9026
>
>P.S.
> As I proof read this a thought occurred: it's possible to reduce the
>distortion of the SE amp, end-to-end, if the last inverting-stage before the
>final is loaded so as to produce a transfer curve that is the inverse of the
>final. This is called Complementary Distortion Reduction and the notion has
>been around for 40 years at least.
> In terms of distortion reduction, it's almost feedback but without the
>inevitable higher order non-linearities, the loop delay and the consequent
>creation of a chaotic, low-level noise "floor".
> Driving a low admittance load like a self-biased CF, a choke-loaded
>voltage amplifing stage traverses a dynamic load line is the better part of
>horizontal; triode heaven... So, how does one decrease its linearity?
> Above any rational low frequency, enough inductive reactance becomes a
>virtual current source and that HIGH impedance can be successfully
>degenerated by a parallel resistance of the desired value. Stage gain will
>be sacrificed but maximum output swing will not... bears thinking about...
>later.
>
> zzzzZZZZZzzzzzZZZZZzzzzzZZZZ........
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
=========================================================================
From: pitaro@ozemail.com.au
Subject: Beer Trivia (off topic)
Date: Tue, 26 Aug 1997 08:50:47 EST
Source: Sound Digest Archive v01.n001
Hi all,
Since the list appears to be back up, and since so many of us like
to partake in the amber fluid, I thought I'd pass this piece of info....
Dedicated to Scott!
Courtesy of Pete's Wicked Ale:
It was the accepted practice in Babylonia 4,000 years ago that for a
month after the wedding, the bride's father would supply his son-in-law
with all the mead he could drink. Mead is a honey beer, and because their
calendar was lunar based, this period was called the "honey month" or what
we know today as the "honeymoon".
Before thermometers were invented, brewers would dip a thumb or finger
into the mix to find the right temperature for adding yeast. Too cold,
and the yeast wouldn't grow. Too hot, and the yeast would die. This thumb
in the beer is where we get the phrase "rule of thumb".
In English pubs, ale is ordered by pints and quarts. so in old England,
when customers got unruly, the bartender would yell at them to mind their
own pints and quarts and settle down. It's where we get the phrase
"mind your P's and Q's".
Beer was the reason the Pilgrims landed at Plymouth Rock. It's clear
from the Mayflower's log that the crew didn't want to waste beer looking
for a better site. The log goes on to state that them passengers "were
hasted ashore and made to drink water that the seamen might have the
more beer".
After consuming a bucket or two of vibrant brew they called aul, or
ale, the Vikings would head fearlessly into battle often without armor
or even shirts. In fact, the term "berserk" means "bare shirt" in Norse,
and eventually took on the meaning of their wild battles.
In 1740, Admiral Vernon of the British fleet decided to water down the
navy's rum. Needless to say, the sailors weren't too pleased and
called Admiral Vernon, Old Grog, after the stiff wool grogram coats he
wore. The term "grog" soon began to mean the watered down drink itself.
When you were drunk on this grog, you were "groggy", a word still in use
today.
Many years ago in England, pub frequenters had a whistle baked into the
rim or handle of their ceramic cups. when they needed a refill, they
used the whistle to get some service. "Wet your whistle", is the phrase
inspired by this practice.
In the middle ages, "nunchion" was the word for liquid lunches. It was
a combination of the words "noon scheken", or noon drinking. In those
days, a large chunk of bread was called lunch. So if you ate bread
with your nunchion, you had what we still today call a luncheon.
Regards,
Harry Pitaro
+-----------------------+---------------------------------------------+
| Melbourne, Australia | A good discussion is like a miniskirt; |
| | Short enough to retain interest |
| pitaro@ozemail.com.au | and long enough to cover the subject. |
+-----------------------+---------------------------------------------+
=========================================================================
From: "Bottlehead" <Bottlehead@prodigy.net>
Subject: Before you all jump on me
Date: Wed, 4 Mar 1998 20:34:55 -0800
Source: Sound Digest Archive v01.n208
I was just informed that I left some paragraphs in the Blues Master article
about a grid resistor on the output tube of the direct coupled circuit.
No I'm not really that dumb - originally I intended a cap coupled circuit.
Forgot to cut that section from the article.
Please disregard that section.
Doc B.
=========================================================================
From: "Smith, Richard Todd" <SmithRT@lci.com>
Subject: Beginner
Date: Mon, 12 Jan 1998 10:47:00 -0500
Source: Sound Digest Archive v01.n158
I've recently become inspired by horn design. I've tried making some
small projects of my own, but have ran into trouble making the curve of
the horn with wood. The wood just doesn't bend easily. Can someone
help me? Is there another material I can use to build the horn? Can
any one give me some help in beginning a easy yet worth wild project?
Help, it's frustrating!
Rick
=========================================================================
From: Steven S <stevensl@mindspring.net>
Subject: Re: Beginner
Date: Mon, 12 Jan 1998 11:57:34 -0500
Source: Sound Digest Archive v01.n158
KERF Cuts
basically on the back side of the wood (the side that you wont see) make
cuts on a table saw with a extremely narrow blade about 3/4 the way thru
the piece. This will give the wood "room" to bend easier. The more cuts the
more bend.. practice on some scrap to give the "correct" amount of bend.
Once finished epoxy those cuts so it does not split the wood.
Steven
At 10:47 AM 1/12/98 -0500, Smith, Richard Todd wrote:
>I've recently become inspired by horn design. I've tried making some
>small projects of my own, but have ran into trouble making the curve of
>the horn with wood. The wood just doesn't bend easily. Can someone
>help me? Is there another material I can use to build the horn? Can
>any one give me some help in beginning a easy yet worth wild project?
>Help, it's frustrating!
>
> Rick
>
=========================================================================
From: tronan@orion.it.luc.edu (Thomas Ronan)
Subject: Re: Beginner
Date: Mon, 12 Jan 1998 12:14:38 -0600
Source: Sound Digest Archive v01.n158
>KERF Cuts
>
>basically on the back side of the wood (the side that you wont see) make
>cuts on a table saw with a extremely narrow blade about 3/4 the way thru
>the piece. This will give the wood "room" to bend easier. The more cuts the
>more bend.. practice on some scrap to give the "correct" amount of bend.
>Once finished epoxy those cuts so it does not split the wood.
>
>Steven
Steven,
I had some problems with this technique. Perhaps I was using too thick of
a saw blade...my boards always split and never bent. Do you epoxy after
bending, or before?
Any specific type of wood required for this? Will typical 3/4 ply work, or
do you need a softer wood?
Thanks for the ideas,
Tom
- ------
Thomas Ronan tronan@orion.it.luc.edu
1045 W. Montana, Chicago, IL 60614 773.528.0882
Lowther Club of America, Chicago Representative
=========================================================================
From: dball@esper.com (David Ball)
Subject: Re: Beginner
Date: Mon, 12 Jan 1998 13:37:12 -0500
Source: Sound Digest Archive v01.n158
>>KERF Cuts
>>
>>basically on the back side of the wood (the side that you wont see) make
>>cuts on a table saw with a extremely narrow blade about 3/4 the way thru
>>the piece. This will give the wood "room" to bend easier. The more cuts the
>>more bend.. practice on some scrap to give the "correct" amount of bend.
>>Once finished epoxy those cuts so it does not split the wood.
>>
Another technique that works well is to use "Italian Bending Plywood." (I
don't know if that's a universal name or not--it's what I've found it
called). This is basically a high quality poplar plywood that is very
flexible along one of its dimensions--very stiff in the other dimension. It
can be obtained in different thicknesses, but 3/8" is common, and should
work well for horns. No kerfs required. There are many sources for this
material, but I know it can be found at the Woodworkers' Store
http://woodworkerstore.com/. They aren't the cheapest in town, but they've
always been reliable.
Dave Ball
=========================================================================
From: Steven S <stevensl@mindspring.net>
Subject: Re: Beginner
Date: Mon, 12 Jan 1998 13:46:41 -0500
Source: Sound Digest Archive v01.n158
Um this technique works great for regular woodworking (where i have
experience working with it) Whats important here is reasonable bends you
can do 90 degree bends with the right thickness but its going to depends on
the wood. Thats why a little trial and error is good to tweak it. The only
actual horn i built using this technique (and i'm still building it) i used
a nice birch ply.
I cut the kerfs large where not much bending was needed but along the flare
i got the cuts quite close together. On my example i cut almost to the last
ply layer just a hair below the nice birch. maybe 1/16th below the birch or
so.. then IMPORTANT STEP: wet that puppy down.. soak it... since wood is
typically 5 -10% moisture content it will split with such little to hold it
together so wetting it down will give alot of flex.. but be careful here..
bend it nice and easy and you might opt to bend in stages to allow the wood
to relax.. once bent then fill the back side with wood filler, epoxy,
something somewhat flexable but sturdy.
Once set up this also helps keep it in place.. a bonus...
Personally this is alot of work but if you have the table saw and clamps it
does work well.
Steven
>
>
>Steven,
>
>I had some problems with this technique. Perhaps I was using too thick of
>a saw blade...my boards always split and never bent. Do you epoxy after
>bending, or before?
>
>Any specific type of wood required for this? Will typical 3/4 ply work, or
>do you need a softer wood?
>
>Thanks for the ideas,
>
>Tom
>
>------
>Thomas Ronan tronan@orion.it.luc.edu
>1045 W. Montana, Chicago, IL 60614 773.528.0882
>Lowther Club of America, Chicago Representative
>
>
>
=========================================================================
From: Richard C Nevill <rnevill@is.dal.ca>
Subject: Re: Beginner
Date: Mon, 12 Jan 1998 16:33:10 -0400 (AST)
Source: Sound Digest Archive v01.n158
On Mon, 12 Jan 1998, Thomas Ronan wrote:
> >KERF Cuts
> >
> >basically on the back side of the wood (the side that you wont see) make
> >cuts on a table saw with a extremely narrow blade about 3/4 the way thru
> >the piece. This will give the wood "room" to bend easier. The more cuts the
> >more bend.. practice on some scrap to give the "correct" amount of bend.
> >Once finished epoxy those cuts so it does not split the wood.
> >
> >Steven
>
Don't forget to soak the wood with water also. This may help a bit.
>
> Steven,
>
> I had some problems with this technique. Perhaps I was using too thick of
> a saw blade...my boards always split and never bent. Do you epoxy after
> bending, or before?
>
> Any specific type of wood required for this? Will typical 3/4 ply work, or
> do you need a softer wood?
>
> Thanks for the ideas,
>
> Tom
>
> ------
> Thomas Ronan tronan@orion.it.luc.edu
> 1045 W. Montana, Chicago, IL 60614 773.528.0882
> Lowther Club of America, Chicago Representative
>
>
>
=========================================================================
From: Larry Muirhead <larry@amelia.sp.trw.com>
Subject: Re: Beginner
Date: Tue, 13 Jan 1998 07:19:57 -0800
Source: Sound Digest Archive v01.n159
Thomas Ronan wrote:
>
> >KERF Cuts
> >
> >basically on the back side of the wood (the side that you wont see) make
> >cuts on a table saw with a extremely narrow blade about 3/4 the way thru
> >the piece. This will give the wood "room" to bend easier. The more cuts the
> >more bend.. practice on some scrap to give the "correct" amount of bend.
> >Once finished epoxy those cuts so it does not split the wood.
> >
> >Steven
>
> Steven,
>
> I had some problems with this technique. Perhaps I was using too thick of
> a saw blade...my boards always split and never bent. Do you epoxy after
> bending, or before?
>
> Any specific type of wood required for this? Will typical 3/4 ply work, or
> do you need a softer wood?
>
> Thanks for the ideas,
>
> Tom
You can probably make better curves by building up a bent lamination
out of veneer, but this is not exactly a beginner level woodworking
project. It also requires lots of clamps.
- --
Larry Muirhead larry@amelia.sp.trw.com
Computational Physicist, TRW
These are not the opinions of TRW.
=========================================================================
From: "Frank Deutschmann" <fdeutsch@blackrock.com>
Subject: Re: Beginner
Date: Tue, 13 Jan 1998 17:27:26 -0500
Source: Sound Digest Archive v01.n160
On Jan 13, 7:19am, Larry Muirhead wrote:
> You can probably make better curves by building up a bent lamination
> out of veneer, but this is not exactly a beginner level woodworking
> project. It also requires lots of clamps.
One approach to this (though again, not beginner level!) is to use vacuum
bagging; I have done quite a bit of building both wooden laminate and
composite layup structures using a home-built vacuum bagging system. Its
nothing more than some very large sheets of heavy plastic sheeting and a
ShopVac; though I can't do anything that requires an autoclave (no
heat-activated pre-peg materials), it does work for most everything else.
Positive molds work best; negative molds (concave curvature) can lead to
problems with the final shape tracking the mold.
I've never built anything audio in this arangement, but it might be
interesting to think about the ideal composite structure to use to give
maximal damping....
- -frank
=========================================================================
From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: belated widtwe (long - sorry)
Date: Fri, 01 May 1998 12:34:22 -0400
Source: Sound Digest Archive v01.n266
hi guys,
been a little swamped lately...
i haven't posted to the list as much as i would have liked.
so this report might actually cover the last few weekends
this past weekend i went to the Philly triode show in
valley forge, pa.
was good to see a few familliar faces and meet some new ones.
the show was pretty interesting.
i won't give a "review"
unless someone is actually interested in my opinion... ;)
you can get the scoop from steve rochlin at:
http://www.enjoythemusic.com/patubeshow.htm
i was busy saturday before
re-doing the dc-dc converter for my tube car stereo.
it worked well enough, but the snubbers were running a little hot.
since i originally place the supply in my glovebox
i didn't want to start a fire!
i re-designed the flyback tranny for lower leakage inductance
and that solved the problem.
i repackaged the power supply in a small plastic box i had lying around,
so i didn't need to hide it in the glovebox any more.
i put it right on top of the dash next to the tube amp.
some of the guys got a kick out of seeing the little st shaped 1626's
sticking up out of the dashboard. (looks really cool at night -
the ride home was a lot of fun)
didn't have the nerve to grab steve rochlin of harvey to show them.
but i should have... ;(
i brought my little "darling" (SE 1626) amp with me, just in case
there was some quiet time to demo it...
the whole thing, plus an extra set of tubes
fit into my laptop case
given the trouble the 2a3's were having (both the normal 2.5W 2a3 amps
and those special cary 5W 2a3 amps (sic) )
i figured that 0.7W would not cut it in this environment.
again i chickened out.
i got a pair of svetlana 300B's a few weeks ago.
but i've been too busy to do anything with them yet!!?
maybe tonight i'll cobble something together after i put the kids to bed...
i'm sorta set up to retrofit my old stereo se sv811-10 amp
http://www.geocities.com/TimesSquare/1965/se_sv811.html
picture: http://www.geocities.com/TimesSquare/1965/sv811photo3.jpg
with the 300B's.
the old driver was 6sl7/6sn7/6as7 (CF).
given the three octal sockets, i was thinking
12sl7 and two 1626 drivers.
the power supply is only about 420V @ 250mA + with SS rectifiers
so i was thinking of doing a "low&hot" on these suckers
using cathode bias.
but i might just use the built in -130 V supply for fixed bias.
hell, you know i'll do both... and i'll build in a switch to select cathode
or
fixed bias before i'm done.....
i sorta finished the pp 2a3 amp using the knight-kit power supply
and output trannies.
need some more work, though.
i need to put in a couple balance pots to even out the bias between the
differential dc-coupled 1st and 2nd stage.
it's similar to the tube-o-saur, published on steve berger's
aprilsound page:
http://home.earthlink.net/~aprilsound/PP2A3_amp.gif
except i dispensed with the higher driver supply voltage
and choke-loaded the 2nd stage...
i also picked up a pair of tango u808's from steve at the show.
i'm planning on putting these into my 45/245/2a3 amp.
i never got this amp to it's full potential. maybe the iron will do the
trick...
this way i can put the UBT-2's into the 300B amp.
since they're rated at 110ma, they'd probably do a better "low&hot"...?
how would the U808 work for 300B...? hmm.....
i also want to try the U808's in one of my 1626 amps.
these might make a nice upgrade for the 3 copies of the 1626 amp that i've
sold, so far.... ;)
well, there goes my lunch hour....
bob.d.
=========================================================================
From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: RE: belated widtwe (long - sorry)
Date: Mon, 04 May 1998 13:21:45 -0400
Source: Sound Digest Archive v01.n268
> From: dslagle@earthlink.net[SMTP:dslagle@earthlink.net]
> Sent: Friday, May 01, 1998 7:11 PM
> To: Danielak, Robert M
> Subject: Re: belated widtwe (long - sorry)
>
>
> >some of the guys got a kick out of seeing the little st shaped 1626's
> >sticking up out of the dashboard. (looks really cool at night -
> >the ride home was a lot of fun)
> >
>
> bob you are too humble,
>
> i had the chance to audition this lil beauty, when bob and i and (jc's
> friend.. i don't recall her name) went back to try to locate johannes and
> (another lost name sorry... but lost name person...email me)
>
peter rudy(sp?)
> immediately it was an eye opening experience...
>
was that the sound, or the ride?
when we drove into oncoming traffic, i CLOSED my eyes..... ;{}
> listen it was 7/10 of a
> watt and didn't play too loud, but boy it was unlike any car system i had
> ever heard before! it was just easy to listen too! one compairison
> between this and a high quality sony car deck would do more to sell people
> on tubes than any other compairison i know... it was just right! (i am
> becoming a huge fan of the $250DD 1626)
>
> the intallation made me feel like i was at home (sorry bob) butit was
> definately a sight! (how bout some pics bob)
>
yeah, i should get a few snaps of this one before i make it too
neat and pretty.
i'm thinking of just putting an X_RAY or radiation sign on the dash.
it'll be a combination stereo and theft-deterrent system ;)
actually, i've somewhat improved the amp and power supply
this past weekend.
it had a rather low input impedance (was going to drive it from
speaker outputs). but this amp had line out, and it was loading down.
changed to 270K input resistors and got at least twice the volume
and less disto.
i still cheat a little. the back speakers are powered via the car stereo's
25WPC outputs (turned fader way down, though).
the aluminum "sex" speaks in the door panel don't get much bass, otherwise.
i got pulled over this morn. on the way to work.
supposedly for not wearing my seatbelt and a headlight was out,
but i think the trooper was curious about my rig
(ya know the unibomber was from NJ....)
he didn't write me a ticket after i showed him it was just an amp...
(although he didn't seem to appreciate my comment that the tubes
we made before he was born...?)
> one humorous note:
>
> after dinner we all went out to look at the installation and bob took the
> keys and couldn't get the drivers door open, he tossed the keys over to
> the
> passenger sid and someone got the door open somehow.. crawled in and
> opened
> the door for bob... bob looked in the car... a panicked look came over his
> face.. not because someone stole his custom tube in the dash 1626 SE amp,
> but becaus he just broke into someone elses blue car!!! A short trip
> across the parking lot brought us to his car... tubes proudly perched on
> ths dash....
>
yeah, and blackie suggested that i go get my amp and put it in THAT
car. it was in much nicer shape, and it had a sunroof!
> as for my impressions of the show.... i don't know if its an attitude or
> what, but the NYTM definately took the honors in my book.
>
AB-SO-LUTELY
bob.d.
=========================================================================
From: donnak1@208.134.169.11
Subject: Belive it or not it works!!!
Date: Mon, 26 Jan 98 09:05:08 EST
Source: Sound Digest Archive v01.n171
I Never Thought I'd Be the One Telling You This...
>
> I Actually Read & Acted on a Piece of E-Mail,
> And Now I'm Going to Europe for the Holidays!
>
> Hello!
>
> My name is Karen Liddell; I'm a 35-year-old mom, wife, and part-time
> accountant. As a rule, I delete all unsolicited "junk" e-mail and use
> my
> account primarily for business. I received what I assumed was this
> same e-
> mail countless times and deleted it each time.
>
> About two months ago I received it again and, because of the catchy
> subject
> line, I finally read it. Afterwards, I thought , "OK, I give in, I'm
> going
> to try this. I can certainly afford to invest $20 and, on the other
> hand,
> there's nothing wrong with creating a little excess cash." I promptly
> mailed
> four $5 bills and, after receiving the reports, paid a friend of mine a
> small
> fee to send out some e-mail advertisements for me. After reading the
> reports,
> I also learned how easy it is to bulk e-mail for free!
>
> I was not prepared for the results. Everyday for the last six weeks,
> my P.O.
> box has been overflowing with $5 bills; many days the excess fills up
> an extra
> mail bin and I've had to upgrade to the corporate-size box! I am
> stunned by
> all the cash that keeps rolling in!
>
> My husband and I have been saving for several years to make a
> substantial
> downpayment on a house. Now, not only are we purchasing a house with
> 40%
> down, we're going to Venice, Italy for the holidays to celebrate!
>
> I promise you, if you follow the directions in this e-mail and be
> prepared to
> eventually set aside about an hour each day to follow up (and count your
> money!), you will make at least as much money as we did. You don't
> need to be
> a wiz at the computer, but I'll bet you already are. If you can open
> an
> envelope, remove the money, and send an e-mail message, then you're on
> your
> way to the bank. Take the time to read this so you'll understand how
> easy it
> is. If I can do this, so can you!
>
> GO FOR IT NOW!
> ........Karen Liddell
>
> The following is a copy of the e-mail I read:
>
> $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
>
> This is a LEGAL, LOW-COST, MONEY-MAKING PHENOMENON.
>
> PRINT this letter, read the directions, THEN GET STARTED TODAY!
>
> You are about to embark on the most profitable and unique program you
> may ever
> see. Many times over, it has demonstrated and proven its ability to
> generate
> large amounts of cash. This program is showing fantastic appeal with a
> huge
> and ever-growing on-line population desirous of additional income.
>
> This is a legitimate, LEGAL, money-making opportunity. It does not
> require
> you to come in contact with people, do any hard work, and best of all,
> you
> never have to leave the house, except to get the mail and go to the
> bank!
>
> This truly is that lucky break you've been waiting for! Simply follow
> the
> easy instructions in this letter, and your financial dreams will come
> true!
> When followed correctly, this electronic, multi-level marketing program
> works
> perfectly... 100% OF THE TIME!
>
> Thousands of people have used this program to:
>
> - Raise capital to start their own business
> - Pay off debts
> - Buy homes, cars, etc.,
> - Even retire!
>
> This is your chance, so read on and get started today!
>
> ------------------------------------------------------------------------------
> ----
> OVERVIEW OF THIS EXTRAORDINARY
> ELECTRONIC MULTI-LEVEL MARKETING PROGRAM
> ------------------------------------------------------------------------------
> ----
>
> Basically, this is what we do:
>
> We send thousands of people a product for $5.00 that costs next to
> nothing to
> produce and e-mail. As with all multi-level businesses, we build our
> business
> by recruiting new partners and selling our products. Every state in
> the U.S.
> allows you to recruit new multi- level business online (via your
> computer).
>
> The products in this program are a series of four business and financial
> reports costing $5.00 each. Each order you receive via "snail mail"
> will
> include:
>
> * $5.00 cash
> * The name and number of the report they are ordering
> * The e-mail address where you will e-mail them the
> report they ordered.
>
> To fill each order, you simply e-mail the product to the buyer. THAT'S
> IT!
> The $5.00 is yours! This is the EASIEST electronic multi-level
> marketing
> business anywhere!
>
> FOLLOW THE INSTRUCTIONS TO THE LETTER AND
> BE PREPARED TO REAP THE STAGGERING BENEFITS!
>
> ******* I N S T R U C T I O N S *******
>
> This is what you MUST do:
>
> 1. Order all 4 reports shown on the list below (you can't
>
>
> sell them if you don't order them).
>
> * For each report, send $5.00 CASH, the NAME & NUMBER OF THE
> REPORT YOU
> ARE ORDERING, YOUR E-MAIL ADDRESS, and YOUR NAME & RETURN ADDRESS (in
> case of
> a problem) to the person whose name appears on the list next to the
> report.
> MAKE SURE YOUR RETURN ADDRESS IS ON YOUR ENVELOPE IN CASE OF ANY MAIL
> PROBLEMS!
>
> * When you place your order, make sure you order each of the four
> reports. You will need all four reports so that you can save them on
> your
> computer and resell them.
>
> * Within a few days you will receive, via e-mail, each of the four
> reports. Save them on your computer so they will be accessible for you
> to send
> to the 1,000's of people who will order them from you.
>
> 2. IMPORTANT-- DO NOT alter the names of the people who are listed
> next to
> each report, or their sequence on the list, in any way other than is
> instructed below in steps "a" through "f" or you will lose out on the
> majority
> of your profits. Once you understand the way
> this works, you'll also see how it doesn't work if you change it.
> Remember, this method has been tested, and if you alter it, it
> will not
> work. ( I talked to a friend last month who has also done this
> program. He
> said he had tried "playing" with it to change the results. Bad
> idea.... he
> never got as much money as he did with
> the un-altered version. Remember, it's a proven
> method !
>
> a. Look below for the listing of available reports.
>
> b. After you've ordered the four reports, take this advertisement
> and
> remove the name and address under REPORT #4. This person has made it
> through
> the cycle and is no doubt counting their 50 grand!
>
> c. Move the name and address under REPORT #3 down to REPORT #4.
>
> d. Move the name and address under REPORT #2 down to REPORT #3.
>
> e. Move the name and address under REPORT #1 down to REPORT #2.
>
> f. Insert your name/address in the REPORT #1 position.
>
> Please make sure you copy every name and address ACCURATELY!
>
> 3. Take this entire letter, including the modified list of names, and
> save it
> to your computer. Make NO changes to the instruction portion of this
> letter.
>
> 4. Now you're ready to start an advertising campaign on the INTERNET!
> Advertising on the 'Net is very, very inexpensive, and there are
> HUNDREDS of
> FREE places to advertise. Another avenue which you could use for
> advertising
> is e-mail lists. You can buy these lists for under $20/2,000
> addresses or
> you can pay someone a minimal charge to take care of it for you.
> BE SURE TO START YOUR AD CAMPAIGN IMMEDIATELY!
>
> 5. For every $5.00 you receive, all you must do is e-mail them the
> report
> they ordered. THAT'S IT! ALWAYS PROVIDE SAME-DAY SERVICE ON ALL
> ORDERS!
> This will guarantee that the e-mail THEY send out, with YOUR name and
> address
> on it, will be prompt because they can't advertise until they receive
> the
> report!
>
> ------------------------------------------
> AVAILABLE REPORTS
> ------------------------------------------
>
> *** Order Each REPORT by NUMBER and NAME ***
>
> Notes:
>
> - ALWAYS SEND $5 CASH (U.S. CURRENCY) FOR EACH REPORT
> CHECKS NOT ACCEPTED
> - ALWAYS SEND YOUR ORDER VIA FIRST CLASS MAIL
> - Make sure the cash is concealed by wrapping it in at least two
> sheets of paper
> - On one of those sheets of paper, include: (a) the number & name
> of the report you are ordering, (b) your e-mail address, and
> (c) your name & postal address.
>
> PLACE YOUR ORDER FOR THESE REPORTS NOW:
> _______________________________________________________________
>
> REPORT #1 "HOW TO MAKE $250,000 THROUGH MULTI-LEVEL SALES"
>
> ORDER REPORT #1 FROM:
> C.C. , Inc.
> 606 Giffin Court
> Hockessin , DE 19707
> _______________________________________________________________
>
> REPORT #2 "MAJOR CORPORATIONS AND MULTI-LEVEL SALES"
>
> ORDER REPORT #2 FROM:
> CalvinPhil
> 2546 N. Morrison Road
> Muncie, IN 47304
> ____________________________________
>
> REPORT #3 "SOURCES FOR THE BEST MAILING LISTS"
>
> ORDER REPORT #3 FROM:
> Reddoggy Enterprises
> P.O. Box 14109
> Springfield, MO 65814
>
> _______________________________________________________________
>
> REPORT #4 "EVALUATING MULTI-LEVEL SALES PLANS"
>
> ORDER REPORT #4 FROM:
> JDR
> 2101 W. Chesterfield
> C-100125
> Srpingfield, MO 65807
>
> _______________________________________________________________
>
> ------------------------------------------------------------------------------
> ------------------
> HERE'S HOW THIS AMAZING PLAN WILL MAKE YOU $MONEY$
> ------------------------------------------------------------------------------
> ------------------
>
> Let's say you decide to start small just to see how well it works.
> Assume your
> goal is to get 10 people to participate on your first level. (Placing a
> lot of
> FREE ads on the internet will EASILY get a larger response.) Also
> assume that
> everyone else in YOUR ORGANIZATION gets ONLY 10 downline members.
> Follow this
> example to achieve the STAGGERING results below.
>
> 1st level--your 10 members with
> $5............................................$50
> 2nd level--10 members from those 10 ($5 x 100).....................$500
> 3rd level--10 members from those 100 ($5 x 1,000)............$5,000
> 4th level--10 members from those 1,000 ($5 x 10,000)...$50,000
> THIS TOTALS ----------->$55,550
>
> Remember friends, this assumes that the people who participate only
> recruit 10
> people each. Think for a moment what would happen if they got 20
> people to
> participate! Most people get 100's of participants! THINK ABOUT IT!
>
> Your cost to participate in this is practically nothing (surely you can
> afford
> $20). You obviously already have an Internet connection and e-mail is
> FREE!
>
> REPORT#3 shows you the most productive methods for bulk e-mailing and
> purchasing e-mail lists. Some list & bulk e-mail vendors even work on
> trade!
>
> About 50,000 new people get online every month!
>
> ******* TIPS FOR SUCCESS *******
>
> * TREAT THIS AS YOUR BUSINESS! Be prompt, professional, and
> follow the directions accurately.
>
> * Send for the four reports IMMEDIATELY so you will have them
> when the orders start coming in because:
>
> When you receive a $5 order, you MUST send out the requested
> product/report to comply with the U.S. Postal & Lottery Laws,
> Title
> 18,Sections 1302 and 1341 or Title 18, Section 3005 in the
> U.S. Code,
> also Code of Federal Regs. vol. 16, Sections 255 and 436, which
> state
> that "a product or service must be exchanged for money
> received."
>
> * ALWAYS PROVIDE SAME-DAY SERVICE ON THE ORDERS YOU RECEIVE.
>
> * Be patient and persistent with this program. If you follow the
> instructions exactly, your results WILL be SUCCESSFUL!
>
> * ABOVE ALL, HAVE FAITH IN YOURSELF AND KNOW YOU WILL
> SUCCEED!
>
> ******* YOUR SUCCESS GUIDELINES *******
>
> Follow these guidelines to guarantee your success:
>
> If you don't receive 10 to 20 orders for REPORT #1 within two weeks,
> continue
> advertising until you do. Then, a couple of weeks later you should
> receive at
> least 100 orders for REPORT #2. If you don't, continue advertising
> until you
> do.
>
> Once you have received 100 or more orders for REPORT #2, YOU CAN RELAX,
> because the system is already working for you, and the cash will
> continue to
> roll in!
>
> THIS IS IMPORTANT TO REMEMBER:
>
> Every time your name is moved down on the list, you are placed in front
> of a
> DIFFERENT report. You can KEEP TRACK of your PROGRESS by watching which
> report people are ordering from you. If you want to generate more
> income,
> send another batch of e-mails and start the whole process again! There
> is no
> limit to the income you will generate from this business!
>
> T E S T I M O N I A L S *******
>
> This program does work, but you must follow it EXACTLY!
> Especially the
> rule of not trying to place your name in a different position, it won't
> work
> and you'll lose a lot of potential income. I'm living proof that it
> works.
> It really is a great opportunity to make relatively easy money, with
> little
> cost to you. If you do choose to participate, follow the program
> exactly, and
> you'll be on your way to financial security.
> Sean McLaughlin, Jackson, MS
>
> My name is Frank. My wife, Doris, and I live in Bel-Air, MD. I am
> a cost
> accountant with a major U.S. Corporation and I make pretty good money.
> When I
> received the program I grumbled to Doris about receiving "junk mail." I
> made
> fun of the whole thing, spouting my knowledge of the population and
> percentages involved. I "knew" it wouldn't work. Doris totally ignored
> my
> supposed intelligence and jumped in with both feet. I made merciless
> fun of
> her, and was ready to lay the old "I told you so" on her when the thing
> didn't
> work... well, the laugh was on me! Within two weeks she had received
> over 50
> responses. Within 45 days she had received over $147,200 in $5 bills! I
> was
> shocked! I was sure that I had it all figured and that it wouldn't
> work. I
> AM a believer now. I have joined Doris in her "hobby." I did have
> seven more
> years until retirement, but I think of the "rat race" and it's not for
> me. We
> owe it all to MLM.
> Frank T., Bel-Air, MD
>
> I just want to pass along my best wishes and encouragement to you.
> Any
> doubts you have will vanish when your first orders come in. I even
> checked
> with the U.S. Post Office to verify that the plan was legal. It
> definitely is!
> IT WORKS!!!
> Paul Johnson, Raleigh, NC
>
> The main reason for this letter is to convince you that this system
> is
> honest, lawful, extremely profitable, and is a way to get a large
> amount of
> money in a short time. I was approached several times before I checked
> this
> out. I joined just to see what one could expect in return for the
> minimal
> effort and money required. To my astonishment, I received $36,470.00
> in the
> first 14 weeks, with money still coming in.
> Sincerely yours, Phillip A. Brown, Esq.
>
> Not being the gambling type, it took me several weeks to make up my
> mind
> to participate in this plan. But conservative that I am, I decided that
> the
> initial investment was so little that there was just no way that I
> wouldn't
> get enough orders to at least get my money back. Boy, was I surprised
> when I
> found my medium-size post office box crammed with orders! For awhile,
> it got
> so overloaded that I had to start picking up my mail at the window.
> I'll make
> more money this year than any 10 years of my life before. The nice
> thing about
> this deal is that it doesn't matter where in the U.S. the people live.
> There
> simply isn't a better investment with a faster return.
> Mary Rockland, Lansing, MI
>
> I had received this program before. I deleted it, but later I
> wondered if
> I shouldn't have given it a try. Of course, I had no idea who to
> contact to
> get another copy, so I had to wait until I was e-mailed another
> program...11
> months passed then it came...I didn't delete this one!...I made more
> than
> $41,000 on the first try!!
> D. Wilburn, Muncie, IN
>
> This is my third time to participate in this plan. We have quit
> our jobs,
> and will soon buy a home on the beach and live off the interest on our
> money.
> The only way on earth that this plan will work for you is if you do it.
> For
> your sake, and for your family's sake don't pass up this golden
> opportunity.
> Good luck and happy spending!
> Charles Fairchild, Spokane, WA
>
> ORDER YOUR REPORTS TODAY AND
> GET STARTED ON YOUR ROAD TO
> FINANCIAL FREEDOM!
>
> NOW IS THE TIME FOR YOUR TURN
>
> DECISIVE ACTION YIELDS
> POWERFUL RESULTS
>
>
=========================================================================
From: Joe Roberts <jroberts@io.com>
Subject: Bell 2145A Schemo??
Date: Wed, 15 Jul 1998 23:46:50 -0500 (CDT)
Source: Sound Digest Archive v01.n345
Hey, any of you scholars remember where the Bell 2145A schematic was
published? Think it was Radio-Electronics or Radio and TV News 1952-1954.
Got the mags but they are deep in my 120 degree oven storage locker and I
can't hang around in there too long! Maybe it's 140 degrees. Freakin hot
in Texas. Joe
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: Bell 2145A Schemo??
Date: Thu, 16 Jul 1998 18:54:04 GMT
Source: Sound Digest Archive v01.n345
On Wed, 15 Jul 1998 23:46:50 -0500 (CDT), Joe Roberts
<jroberts@io.com> wrote:
>Freakin hot in Texas.
They left that part out of the sales brochure, huh? Bet it's nice in
Philly right now....
- --dnb
=========================================================================
From: Acrosound@aol.com
Subject: Re: Re: Bell 2145A Schemo??
Date: Thu, 16 Jul 1998 18:44:21 EDT
Source: Sound Digest Archive v01.n346
Joe-pa bitched that is was:
>
>>Freakin hot in Texas.
and Mr. Barnett suggested that:
>Bet it's nice in Philly right now....
Nope. Freakin hot in Philly.
and muggy to boot. feels like someone hit ya with a baseball bat.
don't believe me, just ask Lynno about his summertime visit to Philly.
Hey, just got my tix to Seattle....can I bring my bermudas???
Mikey
=========================================================================
From: Thomas Danley <Tom@ppci.com>
Subject: Benchmark Transformer
Date: Mon, 10 Aug 1998 19:31:46 -0500
Source: Sound Digest Archive v01.n383
Hi All
I have wound a few output transformers in the past and may have stumbled
on something interesting. I have built several prototypes for the
company that hired us and the seemed to be pretty good (bandwidth etc)
however that was for a 225 watt amplifier (6, EL-34's). That job is
over and I can persue it myself.
To do that I need to have a reference standard to compare prototypes to
when
computer modeling.
What I would like to find is documentation for good quality more typical
sized device say in the 50 -75 watts range.
I need to know details like the turns and gage, stack dimensions and
inter leave pattern, also the electrical measurements for it.
If it is a simple matter to copy, I would be interested to see the same
for a good SET transformer.
If any of you guys can supply me with this I would be most gratefull.
Tom Danley
=========================================================================
From: Thomas Danley <Tom@ppci.com>
Subject: Re: Bench Safety,
Date: Sat, 25 Jul 1998 12:30:52 -0500
Source: Sound Digest Archive v01.n359
Hi
While I have been a "conductor" a number of times and "felt the power",
a good friend of mine, a former nuculear engineer on the USS Enterprize
told me of a fellow that got the nick name "Flash" for a lapse in bench
safety he had once and this really stands out in my mind.
The Enterprize has two seperate 16 megawatt steam turbines and
alternator systems to provide electrical power (this is a BIG ship, has
a crew of 5000 people). The turbines and generators are on end and
extend thru a number of deck levels (5 as I recall), these are big.
When it came time to switch between them or when both needed to be "on
line" the procedure was to increase the speed of the un powered unit so
that it was about 1/2 to 1 HZ higher in frequency than the loaded unit.
Then, by watching a phase clock on the wall, as the units are nearly in
phase, the switch is pushed to close the contactors (relays) that put
the two in parallel and the load slows down the faster unit to about the
right speed.
One day it was Flash`s turn to be at the control bench and to do a
change over and perhaps he was out in space or simply looking at his
wristwatch instead of the phase clock, but at around 120 deg, he hit the
switch.
This in effect put the two generators nearly perfectly out of phase in
opposition to each other. Like most industrial stuff there is a large
margin in the design and in this situation with the very large momentum
behind the rotating parts, was able to deliver a considerable amount of
current to the cabinet where the contactors were. This cabinet was about
the size of a large home oven and was about 4 feet off the floor.
When the contactors and circuit breakers exploded the 1/4 thick steel
door deflected most of the blast away from where flash was siting and
fortunatly no one was sitting in front of where the door then slammed
into. Shall we say it must have been an noisy and impressive shower of
sparks to be in a fairly confined space with, surprizing he was only
lightly burned.
5, aproximatly 1 lb silver contacts were totally vaporized as well as a
lot of wire etc. which coated the debris in the box and at the control
bench.
There was also a "jolt" felt tru the ship, one of the generator/turbine
sets broke all the vibration mounts on three decks.
I would have thought that they would have made the guy go start a big
solid fuel rocket by shooting a flare pistol up its rear or some other
similar punishment but all they did was named him Flash.
Tom Danley
=========================================================================
From: Michel Paquette <paqm01@GEL.USherb.CA>
Subject: Re: Bench Safety,
Date: Sat, 25 Jul 1998 17:15:29 -0400 (EDT)
Source: Sound Digest Archive v01.n360
Hi there,
Since everybody talking about cool accidents here's an account from yours
truly.
This happen during my days as a masters student at the university. I was
assisting a professor on a high powered laser system that we have built
together. Now, this laser was the most powerful in Canada at that time
(about 4 years ago) and the 6th most powerful in the world. The peak
output power was over 1 TW. This is 1 000 000 000 000 watts! The laser
system was aligned so that the laser beam would go into a high vacuum
chamber where the experiment would take place. The laser was in stanby
mode in order to prepare for an experiment. I was looking
through the window through which the beam passes through and ZAP! The
laser fired! Right on the back of my head! 1 TW is an awfull lot of power
but fortunatly the pulse length is only 400 fs (or 0.000 000 000 000 4
second) so i didn't get hurt or anything. The professor did see a blue
hue coming from head though.
Oh yeah, during my days as a PhD student, while I was fixing the 200 000
V power supply on the ion implanter....
Deafboy
On Sat, 25 Jul 1998, Thomas Danley
wrote:
> Hi
>
> While I have been a "conductor" a number of times and "felt the power",
> a good friend of mine, a former nuculear engineer on the USS Enterprize
> told me of a fellow that got the nick name "Flash" for a lapse in bench
> safety he had once and this really stands out in my mind.
>
> The Enterprize has two seperate 16 megawatt steam turbines and
> alternator systems to provide electrical power (this is a BIG ship, has
> a crew of 5000 people). The turbines and generators are on end and
> extend thru a number of deck levels (5 as I recall), these are big.
> When it came time to switch between them or when both needed to be "on
> line" the procedure was to increase the speed of the un powered unit so
> that it was about 1/2 to 1 HZ higher in frequency than the loaded unit.
> Then, by watching a phase clock on the wall, as the units are nearly in
> phase, the switch is pushed to close the contactors (relays) that put
> the two in parallel and the load slows down the faster unit to about the
> right speed.
> One day it was Flash`s turn to be at the control bench and to do a
> change over and perhaps he was out in space or simply looking at his
> wristwatch instead of the phase clock, but at around 120 deg, he hit the
> switch.
> This in effect put the two generators nearly perfectly out of phase in
> opposition to each other. Like most industrial stuff there is a large
> margin in the design and in this situation with the very large momentum
> behind the rotating parts, was able to deliver a considerable amount of
> current to the cabinet where the contactors were. This cabinet was about
> the size of a large home oven and was about 4 feet off the floor.
> When the contactors and circuit breakers exploded the 1/4 thick steel
> door deflected most of the blast away from where flash was siting and
> fortunatly no one was sitting in front of where the door then slammed
> into. Shall we say it must have been an noisy and impressive shower of
> sparks to be in a fairly confined space with, surprizing he was only
> lightly burned.
> 5, aproximatly 1 lb silver contacts were totally vaporized as well as a
> lot of wire etc. which coated the debris in the box and at the control
> bench.
> There was also a "jolt" felt tru the ship, one of the generator/turbine
> sets broke all the vibration mounts on three decks.
>
> I would have thought that they would have made the guy go start a big
> solid fuel rocket by shooting a flare pistol up its rear or some other
> similar punishment but all they did was named him Flash.
>
> Tom Danley
>
=========================================================================
From: Scott Grammer <tubedude@cdc.net>
Subject: Re:Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 12:30:31 -0400
Source: Sound Digest Archive v01.n357
Doc B. wrote:
> (snip)
>
> Careful here! 400V can kill you just as dead. (snip)
> The lowly 120V mains can put a
> lot of amps through your heart. We're talkin cardiac BBQ.
>
> Isolation transformers on the bench are a good thing, but most folks don't
> have big enough ones to work with big amps, so you have the potential (pun
> intended) to zap yourself at a variety of potentials when testing an amp
> plugged directly into the mains.
>
> Doc B.
Hear, Hear!While on the subject of safety, and considering that there are always
newbies lurking, I ask the veterans of this hobby to bear with me while I mount
my safety soapbox.
When working on ANYTHING that is powered up, first it is a great idea to use an
isolation transformer. This is a tranny with a 120V primary (240V for those with
such mains voltages) and an identical secondary. Its purpose is to isolate the
entire unit you are working on from earth ground and from the hot side of the
mains voltage. Many people have been hurt by accidentally contacting the live
mains voltage in the unit they are in, and simultaneously being grounded through
a concrete floor, a metal workbench (a bad idea in itself) or through another
grounded device such as a piece of test gear. Incidentally that isolation tranny
can in some instances protect your test gear too.
I work for Sears, Roebuck, and Co. as a Spec 4 Audio tech (I love that job!) and
we have a standardized system concerning grounding schemes. It's actually pretty
simple, and quite safe.
1. Every piece of test gear is earth grounded through the power cord. All
test gear uses 3 wire power cords.
2. The bench is wooden, and therefore does not conduct. We do have a static
drain mat on the bench in deference to the many CMOS devices we work with, but
its connection to ground is made through a 1 Meg resistor, and therefore does
not constitute much of a shock hazard.
3. Anything we work on is powered through a box containing both an isolation
transformer and a variac. This assures that the unit on the bench is isolated
from ground and from the mains.
I would add that a GFI (Ground Fault Interrupter) would be a good idea for
powering a workbench, as it provides an inexpensive extra measure of protection.
About the high AC and DC voltages present in tube gear:
As Doc found out the hard way, AC tends to hold on to you, rather than causing
a muscle contraction and making you jerk away. The muscles in our bodies respond
to electricity (No, I don't know of anybody making a muscle poweres
loudspeaker!) and DC causes them to contract, which results in the involuntary
jerking away that occurs when you accidentally play human voltmeter with your
B+. AC, on the other hand causes a paralysis of the affected muscle, because the
muscle cannot react inside of a single cycle of AC (either 1/100th or 1/120th of
a second, depending on the frequency). Further, AC voltage passes more current
through the body than an equivalent DC voltage, because the body tends to be a
combination of a capacitive and resistive load in parallel. These factors make
AC more dangerous than DC, as was argued by the Edison group, who fought
unsuccessfully for DC power grids in the US in the late 1800's. Edison and his
group unwittingly invented the electric chair when they went from town to town
demonstrating the effect of DC versus AC by electrocuting animals first with DC,
which caused injuries, but not death, and than with AC, which had predictable
effects on the unfortunate animal subject.
As for voltages, any voltage above 20V or so can cause injury, under the right
conditions. Higher voltages just require less stringent conditions to cause
harm. Once you get above 100V even casual contact can cause injury, and solid
contact can be fatal. There is one way to greatly reduce one's risk of injury
due to electrocution while in a powered-up unit, and it is this:
WORK WITH ONE HAND IN A POCKET OR BEHIND YOUR BACK!
If you must make a measurement in a powered unit, use clip leads to connect the
meter or scope before powering up the unit. If you must use a probe in your
hand, use a clip lead for ground, and use only one hand. Don't hold on to the
unit with the other hand. This is a sure way to make all your friends have to
dress in black and stand in the rain. Current passed from one finger to the next
hurts, but current passed from one hand to the other kills. This is because the
heart is in the middle of the path.
Finally, as a warning to those who think they work safely enough, a story of
another tech who thought so too. Here in Chattanooga, at a local repair shop, a
young tech straight out of a two year college went to work fixing microwave
ovens. His intent was to start there and move up. During his first week, he was
given a microwave whose power supply was apparently defective. After arriving
early the next morning, and consequently being the only person in the shop, he
proceded to try to measure the output voltage of the power transformer, using
his bench meter, which did not have a suitable probe and which could not measure
that kind of voltage anyway. His bench was not deep enough to allow him to turn
the microwave so that the power supply faced him (and so he could see what he
was doing), so he left the front of the oven facing out and proceded to lean
across the open unit to make his measurement, after setting the timer to _30
minutes_. About an hour later the secretary came in to work and found the poor
fellow burnt so badly that the paramedics had to cut him away from the
microwave. He had taken the full power of the unit (1,400VAC at 1 amp) for the
full 30 minutes the timer was set for. The paramedics said that he had been
killed almost instantly, and so felt little pain.
This poor guy made 4 fatal errors:
He did not work with one hand.
He did not make sure someone else was present to help in case he got hurt.
He did not make arrangements to work safely, like moving the unit to a bench
large enough that he did not have to lean over it.
He did not use the right test gear, I.E. a High Voltage Probe which would have
been long enough to keep his hand away from the circuitry.
I would suggest to anyone who does not have one, that they find a copy of the
Amateur Radio Relay League Handbook and study up on working safely. I don't like
funerals.
Cheers just dosen't seem right for this instance, so I'll just sign off as.....
S.G.
- --
Check out TubeDude's Webpage of vacuum Tube Lore!
http://www.cdc.net/~tubedude/
=========================================================================
From: "Doc B." <bottlehead@silverlink.net>
Subject: Re: Re:Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 10:03:40 -0700
Source: Sound Digest Archive v01.n358
>He did not make sure someone else was present to help in case he got hurt.
This is a tough one for a lot of us, working in our basement hideaways and
garage laboratories. Makes it all the more important to heed the rest of
Scott's warnings.
I might add to Scott's point of not leaning over your work, don't stick a
probe anywhere you won't be keeping your eye on. Use a clip lead at the end
of the probe if the voltage is low enough to allow this, to attach it to the
test point so you don't have to hold the probe in your shaky hand. This
saves even more circuits than circuit builders. The most common reason I've
seen for blowing components in a circuit is an errant test probe shorting
something it wasn't supposed to touch.
Doc B.
=========================================================================
From: Ed Faulkner <efaulkne@wsunix.wsu.edu>
Subject: Re:Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 11:26:29 -0700
Source: Sound Digest Archive v01.n358
At 12:30 PM 7/24/98 -0400, you wrote:
>Hear, Hear!While on the subject of safety, and considering that there are
always
>newbies lurking, I ask the veterans of this hobby to bear with me while I
mount
>my safety soapbox.
>
Your soapbox ain't nothing compaired to what Uncle Sam gave us in the Navy :-)
I have one lucky friend (still living) who caught a spark from the clystron
in our surface search radar. He flew about 10 feet and required back
surgery to walk again. Lets not forget about these CRTs either, old ones
would hold a charge for a looooong time...
=========================================================================
From: "Doc B." <bottlehead@silverlink.net>
Subject: Re: Re:Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 13:01:34 -0700
Source: Sound Digest Archive v01.n358
>And don't forget your safety glasses for next time you wire a cap
>backwards.
OK, now that you guys know I'm a walking hazard anyway-
I always wear safety glasses when drilling, sawing, etc. but never bothered
when soldering.
I was desoldering a solid core wire from a solder lug a couple weeks ago,
pulled on the wire, and as it popped free a drop of the still liquid solder
flew up and hit me right in the white of my eye.
Shit howdy! Been wearing specs for desolder work ever since.
Squintin Doc B.
=========================================================================
From: Dave Stagner <dstagner@icarus.net>
Subject: Re: Re:Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 13:49:29 -0500 (CDT)
Source: Sound Digest Archive v01.n358
And, for the rest of you longhairs out there, tie your hair back securely!
I tuck my ponytail in the back of my shirt when i'm working. This is more
important for power tools (wanna get your hair caught in a table saw?),
and even soldering (burned hair smells bad and makes for cold joints).
And don't forget your safety glasses for next time you wire a cap
backwards. And make sure you discharge caps! I was mocking up power
supplies in the living room a while back and left a photoflash cap out
with about 300v on it. I found out when i picked it up a couple days
later... ouch! And my wife was justifiably pissed at me, too.
- -dave
Practice beautiful randomness and act kind of senseless.
<dstagner@icarus.net>
=========================================================================
From: Ron Bales <rbales@gte.net>
Subject: Re: Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 14:58:26 -0400
Source: Sound Digest Archive v01.n358
Scott Grammer wrote:
>
> ... These factors make
> AC more dangerous than DC, as was argued by the Edison group, who fought
> unsuccessfully for DC power grids in the US in the late 1800's. Edison and his
> group unwittingly invented the electric chair when they went from town to town
> demonstrating the effect of DC versus AC by electrocuting animals first with DC,
> which caused injuries, but not death, and than with AC, which had predictable
> effects on the unfortunate animal subject.
Two points:
Edison's invention of the AC powered electric chair was VERY witting. He
actually suggested to writers that the word "Westinghouse" should be used
as a verb to describe the procedure; as in "The murderer was westinghoused
at dawn."
Second and more important point: much good safety advice, it doesn't take
long to do things the right way. Thanks for passing this along.
ROn
=========================================================================
From: Richard C Nevill <rnevill@is.dal.ca>
Subject: Re:Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 15:40:47 -0300 (ADT)
Source: Sound Digest Archive v01.n358
My thanks to Scott for the safety lecture on things I knew and things I
didn't. Plus tips on how to set up my bench
Cheers, from a not dead yet
Richard nevill
=========================================================================
From: Scott Grammer <tubedude@cdc.net>
Subject: Re: Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 16:45:31 -0400
Source: Sound Digest Archive v01.n358
Doc B. wrote:
> (snip)
> Shit howdy! Been wearing specs for desolder work ever since.
>
> Squintin Doc B.
I forgot to mention the safety glasses. At work, if you are caught 3 times in
a month working without them, you get a verbal dressing down. Once more, and
it's a written warning, once more and you're out on the street.
BTW, I have updated my site a bit with a page about today's battle with the
ISDN demons at BellSloth (I mean BellSouth). Check it out.
S.G.
- --
Check out TubeDude's Webpage of vacuum Tube Lore!
http://www.cdc.net/~tubedude/
=========================================================================
From: torgd@tolstoy.lerc.nasa.gov (Russell DeAnna)
Subject: Re: Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 16:49:48 -0400 (EDT)
Source: Sound Digest Archive v01.n358
Scott G. wrote:
> 1. Every piece of test gear is earth grounded through the power cord. All
> test gear uses 3 wire power cords.
Fine with me.
> 3. Anything we work on is powered through a box containing both an isolation
> transformer and a variac. This assures that the unit on the bench is isolated
> from ground and from the mains.
But now the device under work doesn't have a chassis ground? I assume the
isolation transformer doesn't have a ground wire linking primary and secondary.
Or are you using an isolation transformer with a ground wire?
Does using a ground wire with an isolation transformer defeat the purpose
of the isolation transformer? If yes, then where do you get the 3rd wire
for earth/chassis ground?
- -Russell
=========================================================================
From: Scott Grammer <tubedude@cdc.net>
Subject: Re: Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 17:05:22 -0400
Source: Sound Digest Archive v01.n358
Russell DeAnna wrote:
> Scott G. wrote:
>
> > 1. Every piece of test gear is earth grounded through the power cord. All
> > test gear uses 3 wire power cords.
>
> Fine with me.
>
> > 3. Anything we work on is powered through a box containing both an isolation
> > transformer and a variac. This assures that the unit on the bench is isolated
> > from ground and from the mains.
>
> But now the device under work doesn't have a chassis ground? I assume the
> isolation transformer doesn't have a ground wire linking primary and secondary.
> Or are you using an isolation transformer with a ground wire?
No, the unit under work is completely isolated from ground and from the mains.
>
>
> Does using a ground wire with an isolation transformer defeat the purpose
> of the isolation transformer? If yes, then where do you get the 3rd wire
> for earth/chassis ground?
>
> -Russell
A ground connection to the secondary would indeed defeat the purpose of the isolation
tranny. The idea is to separate you from the mains, in case there is a fault within
the unit involving the mains connection, or in case you yourself become the fault.
Cheers!
S.G.
- --
Check out TubeDude's Webpage of vacuum Tube Lore!
http://www.cdc.net/~tubedude/
=========================================================================
From: Ron Bales <rbales@gte.net>
Subject: Re: Bench Safety, was 211 vs. 845
Date: Fri, 24 Jul 1998 19:55:27 -0400
Source: Sound Digest Archive v01.n358
Doc B. wrote:
>
>
> I was desoldering a solid core wire from a solder lug a couple weeks ago,
> pulled on the wire, and as it popped free a drop of the still liquid solder
> flew up and hit me right in the white of my eye.
> Shit howdy! Been wearing specs for desolder work ever since.
Wear glasses nearly all my waking hours and I'll tell you, my
desolder/parts-harvesting techniques would be a LOT different if my eyes
weren't protected. How to desolder? Heat the part and then whack it
against the edge of the bench. (okay, within reason)
Now you can use this and other innovative techniques, too.
Seriously, over the years I've scraped so many blobs of solder off my
glasses I'd be afraid to do this work without eye protection.
ROn
Sign in physics lab: "Warning! Do not look at laser with remaining good
eye."
=========================================================================
From: Hartmut <Hartmut.Quaschik@mch.sni.de>
Subject: Re: Bench Safety, was 211 vs. 845
Date: Sat, 25 Jul 1998 14:26:49 +0200
Source: Sound Digest Archive v01.n359
Doc B. wrote:
> saves even more circuits than circuit builders. The most common reason I've
> seen for blowing components in a circuit is an errant test probe shorting
> something it wasn't supposed to touch.
ever saw a 2N33773 power transistor with shorted base to collector by a
probe ? glowing sand pieces all over the place ...
fortunately I am wearing glasses.
Hartmut
=========================================================================
From: Ron Bales <rbales@gte.net>
Subject: Re: Bench Safety, was 211 vs. 845
Date: Mon, 27 Jul 1998 09:16:49 -0400
Source: Sound Digest Archive v01.n360
pitaro@ozemail.com.au wrote:
>
> > I always wear safety glasses when drilling, sawing, etc. but never bothered
> > when soldering.
>
> Yeah...Me too.
>
> I'm suprised that no one has mentioned wearing hearing protection when
> using power tools. Bad mistake not to.
I will on a case by case, but not regularly. I won't tolerate discomfort,
or anything that seems loud enough to leave a hangover. I do scold my
dental tech - there really isn't much in the way of ear protection that
will help the patient, but dental techs are routinely exposed so some
terrible noise.
ROn
=========================================================================
From: pitaro@ozemail.com.au
Subject: Re: Re:Bench Safety, was 211 vs. 845
Date: Mon, 27 Jul 1998 18:26:29 EST
Source: Sound Digest Archive v01.n360
** Reply to note from "Doc B." <bottlehead@silverlink.net> Fri, 24 Jul 1998 13:01:34 -0700
(snip)
> I always wear safety glasses when drilling, sawing, etc. but never bothered
> when soldering.
Yeah...Me too.
I'm suprised that no one has mentioned wearing hearing protection when
using power tools. Bad mistake not to.
Regards,
Harry Pitaro
+-----------------------+---------------------------------------------+
| Melbourne, Australia | A good discussion is like a miniskirt; |
| | Short enough to retain interest |
| pitaro@ozemail.com.au | and long enough to cover the subject. |
+-----------------------+---------------------------------------------+
=========================================================================
From: bart <bartonw@ozemail.com.au>
Subject: RE: Bench Safety, was 211 vs. 845
Date: Thu, 30 Jul 1998 20:41:11 +1000
Source: Sound Digest Archive v01.n367
Gets hot here, so I solder sitting at a table in shorts.
Sure hurts when a big blob of molten solder falls right on your thigh and you watch it solidify by d
umping all its heat into your flesh!
Maybe a leather apron? - na too bloody hot!
Cheers,
Bart
>>
Ron Bales wrote:
pitaro@ozemail.com.au wrote:
>
> > I always wear safety glasses when drilling, sawing, etc. but never bothered
> > when soldering.
>
> Yeah...Me too.
>
> I'm suprised that no one has mentioned wearing hearing protection when
> using power tools. Bad mistake not to.
I will on a case by case, but not regularly. I won't tolerate discomfort,
or anything that seems loud enough to leave a hangover. I do scold my
dental tech - there really isn't much in the way of ear protection that
will help the patient, but dental techs are routinely exposed so some
terrible noise.
ROn
=========================================================================
From: Victor <lowther@linkline.be>
Subject: Berman preamps in S.P. 13
Date: Wed, 24 Sep 1997 08:17:19 +0200
Source: Sound Digest Archive v01.n044
HI There,
In SP 13 (?), I read the Bruce Berman brilliant article on a line preamp.
Has anyone tried it or listened at it ?
Bruce was also mentioning that he was working on a phono preamp, the kind
of beast I am desesperately hunting. Any feedback ?
Does anyone knows his Email ? Of course I do not want to interfere with
future publications in S.P.
Greetings,Victor Meurisse
Musique et Technique magazine
Editor: FINDER PoBox 182 1050 Brussels 5
URL : http://www.lowther.com
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: Re: Berman, WOT preamps
Date: Wed, 22 Oct 1997 11:47:14 -0500
Source: Sound Digest Archive v01.n079
At 11:40 PM -1200 10/22/97, Owen Young wrote:
>Chaps,
>Did someone mention building Berman's Line preamp (SP13)? I'd be keen to
>hear from anyone how it stacks up sonically.
>
>Also on the subject, has anyone tried either of the WOT line pre's in SP10?
>
>I'm thinking about building one of the above. Having some difficulty
>deciding.
>TIA
>
>Owen Young
I have heard a beautifully constructed version of the SP10 preamp. The
builder followed instructions to the letter. It was extremely good
sounding--clean, musical, excellent bass, superb imaging. A bit on the
"dry" side for my tastes, but these types of tubes always sound that way to
me, so take that with a grain of salt. I would say it's one of the better
preamps I've heard. I am about to try a DHT (26) tranny-output preamp
myself. This is another alternative, and Magnequest has some line-output
trannies for tubes of this ilk (26, 56, 76, 6SN7 etc.).
I'm not sure where I got this impression--maybe just from chatter on the
list or talking to other builders in private, but I don't think you can go
wrong with a tranny-output preamp, provided the tranny itself is up to
snuff. The low output impedance, the tranny-loaded plate of the tube, the
simplicity of the circuit all contribute to a very crisp, punchy, neutral
sound. The SP10 circuit is extremely well tested and thought-out. I would
give it a go, or at least try for something similar. I can't imagine you'd
be disappointed.
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: "Owen Young" <oyoung@clear.net.nz>
Subject: Berman, WOT preamps
Date: Wed, 22 Oct 1997 23:40:47 -1200
Source: Sound Digest Archive v01.n079
Chaps,
Did someone mention building Berman's Line preamp (SP13)? I'd be keen to
hear from anyone how it stacks up sonically.
Also on the subject, has anyone tried either of the WOT line pre's in SP10?
I'm thinking about building one of the above. Having some difficulty
deciding.
TIA
Owen Young
=========================================================================
From: "Owen Young" <oyoung@clear.net.nz>
Subject: Berman, WOT preamps
Date: Thu, 23 Oct 1997 10:22:14 -1200
Source: Sound Digest Archive v01.n080
Thanks Grover, Robert R.
Grover, were you referring to the Euridice WOT or Diego Nardi WOT
linestage, both appeared SP10?
Owen Young.
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: Re: Berman, WOT preamps
Date: Thu, 23 Oct 1997 00:30:30 -0500
Source: Sound Digest Archive v01.n081
At 10:22 AM -1200 10/23/97, Owen Young wrote:
>Thanks Grover, Robert R.
>
>Grover, were you referring to the Euridice WOT or Diego Nardi WOT
>linestage, both appeared SP10?
>
>Owen Young.
Oh, nuts, I can't remember, and I don't have my SP10 handy. I think it was
the Euridice--the one with the special-order Italian tranny--is that right??
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: Simon Busbridge <S.C.Busbridge@bton.ac.uk>
Subject: Re: Berman, WOT preamps
Date: Thu, 23 Oct 1997 07:44:21 +0100 (BST)
Source: Sound Digest Archive v01.n081
Grover,
How can I get in touch with Magnequest or find out about their products?
TIA
Simon
Dr Simon Busbridge
University of Brighton
Lewes Road
Moulsecoomb
Brighton BN2 4GJ
UNITED KINGDOM
Tel: 0044 (0)1273 642542
Fax: 0044 (0)1273 642327
e-mail: s.c.busbridge@bton.ac.uk
"..biology is what you do when you don't have the maths for real
science.."
On Wed, 22 Oct 1997, Grover Gardner wrote:
> At 11:40 PM -1200 10/22/97, Owen Young wrote:
> >Chaps,
> >Did someone mention building Berman's Line preamp (SP13)? I'd be keen to
> >hear from anyone how it stacks up sonically.
> >
> >Also on the subject, has anyone tried either of the WOT line pre's in SP10?
> >
> >I'm thinking about building one of the above. Having some difficulty
> >deciding.
> >TIA
> >
> >Owen Young
>
> I have heard a beautifully constructed version of the SP10 preamp. The
> builder followed instructions to the letter. It was extremely good
> sounding--clean, musical, excellent bass, superb imaging. A bit on the
> "dry" side for my tastes, but these types of tubes always sound that way to
> me, so take that with a grain of salt. I would say it's one of the better
> preamps I've heard. I am about to try a DHT (26) tranny-output preamp
> myself. This is another alternative, and Magnequest has some line-output
> trannies for tubes of this ilk (26, 56, 76, 6SN7 etc.).
>
> I'm not sure where I got this impression--maybe just from chatter on the
> list or talking to other builders in private, but I don't think you can go
> wrong with a tranny-output preamp, provided the tranny itself is up to
> snuff. The low output impedance, the tranny-loaded plate of the tube, the
> simplicity of the circuit all contribute to a very crisp, punchy, neutral
> sound. The SP10 circuit is extremely well tested and thought-out. I would
> give it a go, or at least try for something similar. I can't imagine you'd
> be disappointed.
>
>
> Grover Gardner
> groverg@bellatlantic.net
>
>
>
=========================================================================
From: "Owen Young" <oyoung@clear.net.nz>
Subject: Re: Berman, WOT preamps
Date: Fri, 24 Oct 1997 09:21:15 -1200
Source: Sound Digest Archive v01.n082
> From: Grover Gardner <groverg@bellatlantic.net>
> To: Owen Young <oyoung@clear.net.nz>; sound@deliverator.io.com
> Subject: Re: Berman, WOT preamps
> Date: 22 October 1997 17:30
> Oh, nuts, I can't remember, and I don't have my SP10 handy. I think it
was
> the Euridice--the one with the special-order Italian tranny--is that
right??
Grover,
Sorry to be tedious but....actually both were Italian!!
The Diego Nardi WOT used a 5687
The Euridice guys published 2 versions...using a CV5112 or a 417A/5842.
BTW thanks for your encouragement about tranny-output preamps.
Owen Young
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: Re: Berman, WOT preamps
Date: Fri, 24 Oct 1997 01:35:14 -0500
Source: Sound Digest Archive v01.n083
>Grover,
>Sorry to be tedious but....actually both were Italian!!
>The Diego Nardi WOT used a 5687
>The Euridice guys published 2 versions...using a CV5112 or a 417A/5842.
I heard the 5687 preamp.
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: Barton Shepherd <bartonw@ozemail.com.au>
Subject: RE: Berman, WOT preamps
Date: Fri, 24 Oct 1997 17:07:03 +1000
Source: Sound Digest Archive v01.n083
>
I heard the 5687 preamp.
Grover Gardner
>
Well, what was it like?
=========================================================================
From: "Owen Young" <oyoung@clear.net.nz>
Subject: Re: Berman, WOT preamps
Date: Fri, 24 Oct 1997 23:00:34 -1200
Source: Sound Digest Archive v01.n083
Grover,
You wrote:
> I heard the 5687 preamp.
Ah, great....earlier you felt that "these types of tubes" (indirectly
heated triodes?)
are a bit on the "dry" side (lacking warmth, harmonic information?)?
Would you care to expand this a little?
Owen
(p.s. Nobody out there done the Berman pre?)
=========================================================================
From: slagle@dtlweb.com (Dave Slagle)
Subject: Re: Berman, WOT preamps
Date: Fri, 24 Oct 1997 10:50:52 -0400 (EDT)
Source: Sound Digest Archive v01.n084
I have been living with a trannie out linestage of sorts for some time now
and i like it... see other rant.
anyways coming up with iron for these can be a challenge! I seem to
remeber mikey winding something at some point, and I know steve berger
constructed a linestage with a 5687 and a tango output (i think it was an
8-1 stepdown with a 600 ohm out.) anyways building one of these puppies is
simple, the only hudle is coming up with the iron.... hell use an 1:1 IT
and a low Rp power tube ala grover... it'll workas for the sound.. try it
and tell us.
me i am using a 3-2 stepdown trannie with a 5842 running stupid hot, the
trannie is not the greatest bandwidth wise, but neither are my lowthers....
it has sounded better than all the previous cap coupled/ choke loaded
combo's i have tried.
I was thinking that the secondary of these trannies are CT'ed and if i
parallel them I will get a bigger stepdown... will have to give it a try...
later
=========================================================================
From: AirGapped@aol.com
Subject: Re: Berman, WOT preamps
Date: Fri, 24 Oct 1997 12:13:57 -0400 (EDT)
Source: Sound Digest Archive v01.n084
In a message dated 97-10-24 11:53:57 EDT, Dave wrote:
<<
anyways coming up with iron for these can be a challenge! I seem to
remeber mikey winding something at some point, and I know steve berger
constructed a linestage with a 5687 and a tango output (i think it was an
8-1 stepdown with a 600 ohm out.) anyways building one of these puppies is
simple, the only hudle is coming up with the iron.... hell use an 1:1 IT
and a low Rp power tube ala grover... it'll workas for the sound.. try it
and tell us.
>>
The iron should be around a bit. Lundahl, perhaps for some apps the Jensens,
Tangos, and Tamura has a whole list of small signal tranneys at cheapo (not
many bucks) prices. For the Tamura's you might have to go through Koji.
We have several small signal outputs that we are currently making...and I
plan on expanding this lineup a bit (now to figure out what to drop so we
don't overextend ourselves)....
right now we have:
the B7----conventional air gapped single ended----15K pri-----500 ohm CT
secondary----able to handle 8 madc of unbalanced current in the
primary.....limited bass response---say fifty hertz on the bottom.
the B8-----essentially a parafeed version of the B7----same impedances----but
now hefty bass (sub 15 hertz a breeze)----this unit is available with a
permalloy core or in M4 or M6----pick your poison...
soon we will have a B8 but modified to have a 8K primary.....should make it
more suitable for some of the lower Rp tubes.
If you need more poop on these best to either call me on the phone or email
Schmalle....
Mike
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: RE: Berman, WOT preamps
Date: Sat, 25 Oct 1997 04:21:23 -0500
Source: Sound Digest Archive v01.n086
At 5:07 PM +1000 10/24/97, Barton Shepherd wrote:
>>
>I heard the 5687 preamp.
>
>Grover Gardner
>>
>
>Well, what was it like?
As I say, it was a bit on the dry side for my taste. The imaging was
intensely good, the presentation was smooth, bass really excellent and it
was notably good in the bandwidth department--it was musical enough and
very uncolored. Certainly better than your garden-variety preamp. Maybe
missing a bit of "fun"...? I happen to think 5687s are a bit on the
"serious" side. Honestly I can't offer much more than that. It wasn't my
system and it was only an hour or so of listening. I did use my own amps
and noticed the difference in sound with and without the preamp, which is
where my comments come from.
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: Re: Berman, WOT preamps
Date: Sat, 25 Oct 1997 04:31:29 -0500
Source: Sound Digest Archive v01.n086
At 11:00 PM -1200 10/24/97, Owen Young wrote:
>Grover,
>You wrote:
>> I heard the 5687 preamp.
>
>Ah, great....earlier you felt that "these types of tubes" (indirectly
>heated triodes?)
>are a bit on the "dry" side (lacking warmth, harmonic information?)?
>Would you care to expand this a little?
Just to clarify, IMHO--lacking warmth, yes. Lacking harmonic information,
no. The latter seems to be improved with this type of tube, which is why,
I guess, people use them. But my impression is that, unless handled
carefully, the 5687 has a "bite" that doesn't sit well with me.
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: Berning's Zero Hysteresis Amp
Date: Wed, 21 Oct 1998 18:36:26 +0200
Source: Sound Digest Archive v01.n462
- ----------
> De : Sellek, Grant (TSA) <Grant.Sellek@roads.sa.gov.au>
> A : 'Sound Practices' <sound@lists.io.com>
> Objet : Berning's Zero Hysteresis Amp
> Date : mercredi 21 octobre 1998 15:26
>
> Hi All,
>
> I don't recall any discussion on Joenet of David Berning's Zero
Hysteresis
> amps. Has anyone had a look at these?
> http://www.milbert.com/db/zh270.htm
> http://www.milbert.com/db/SiegBroch.htm
> http://www.milbert.com/db/dbzhas.htm
>
> The idea is to replace the OPT with a different kind of impedance
> transformer, using switching power supply technology to convert the audio
> impedance with an RF carrier. Berning's paper (the last of the three
links
> above) considers a 6L6 and concludes "In an audio application, the tube
> behaves as if it is driving a 4k ohm speaker (the impedance conversion
ratio
> goes as the square of the turns ratio), and the speaker acts and sounds
as
> if it is being driven by a 0.6 ohm triode."
> Has anybody heard these things? Has anyone tried to play with the
technology
> ideas? What stops this idea making the OPT obsolete? (again)...... Should
> the SE eXperimenter be looking into this?
> Or is there an Achilles' heel? Either technically, or sonically?
Dear Grant,
I read on that webpage:
"The Berning ZH amplifier performs the impedance matching function of the
output transformer by applying special switching power supply technology.
This technology (patent allowed) uses radio-frequency to change the tube
transfer characteristics from their normal impedance plane to one suitable
for driving a speaker. Because the audio impedance conversion is done with
an RF carrier, it is not subject to the distortions imposed by the audio
output transformer as shown in fig. 3."
The so called "new technology" used in that amplifier is used from long
times in SS audio amplifiers.
I remember a Sony TAF08 or something like that, SS amplifier that used that
technology.
I used to listen to that marvel of technology but for the benefit of the
Joelist I prefer not to give my listening impressions...
I don't remember of any application to tube amplifier but I guess that such
an application cannot benefit of the use of a tube.
In fact the amplifying active element doesn't bother with such technology.
Tube or transistor will sound the same. The sonic result is mainly related
on how the envelop recovering of the HF signal is performed. It could give
good results if this opertaion was well implemented but in that case the
cost will be, IMHO, over the cost of a conventional tube amplifier. My
opinion is that generally this technology is applied to produce low
building cost amplifiers that you could sell at the high price arguing of
the "new technology argument".
BTW It seems to me that the hysterisis argument is flawed in their text.
The hysterisis of an OPT leads mainly to a change of phase in the signal.
Nothing hurts there.
About the harmonic distortion: for sure a PP OPT will have more H3 because
it is more symetrical but a SE OPT will produce mainly the benefitial H2.
Best regards.
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@roads.sa.gov.au>
Subject: Berning's Zero Hysteresis Amp
Date: Wed, 21 Oct 1998 22:56:11 +0930
Source: Sound Digest Archive v01.n462
Hi All,
I don't recall any discussion on Joenet of David Berning's Zero Hysteresis
amps. Has anyone had a look at these?
http://www.milbert.com/db/zh270.htm
http://www.milbert.com/db/SiegBroch.htm
http://www.milbert.com/db/dbzhas.htm
The idea is to replace the OPT with a different kind of impedance
transformer, using switching power supply technology to convert the audio
impedance with an RF carrier. Berning's paper (the last of the three links
above) considers a 6L6 and concludes "In an audio application, the tube
behaves as if it is driving a 4k ohm speaker (the impedance conversion ratio
goes as the square of the turns ratio), and the speaker acts and sounds as
if it is being driven by a 0.6 ohm triode."
The curve traces on the output side of the Berning impedance transformer are
very impressive for their lack of hysteresis. The Siegfried amp is a very
impressive looking 12W SE amp with no audio NFB using the SV811-10 or
WE300B. US$6000-$7000 though.
Has anybody heard these things? Has anyone tried to play with the technology
ideas? What stops this idea making the OPT obsolete? (again)...... Should
the SE eXperimenter be looking into this?
Or is there an Achilles' heel? Either technically, or sonically?
And if anyone can explain the principle in less quasi-patent-conscious
language so even I can understand it, it would be great.
Grant
Grant Sellek
Adelaide, Australia
grant.sellek@roads.sa.gov.au
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: Berning's Zero Hysteresis Amp
Date: Wed, 21 Oct 1998 10:55:06 PDT
Source: Sound Digest Archive v01.n463
Hi all,
>I don't recall any discussion on Joenet of David Berning's
>Zero Hysteresis amps. Has anyone had a look at these?
I had a look at the Patent.
Here is a condensed and simplified description of the Principle:
It appears that Mr. Berning uses a Switched Powersupply at 200kHz
(seemingly in Push-Pull) to provide a rectified but UNSMOOTHED Supply to
the Valves in question. This Voltage is stepped up by a TRANSFORMER to
provide a HT high enough for the Valves in question.
So the Output valve is effectively fed by 200kHz Square-Waves.
The Valve(s) in turn modulate the Current Drawn by the Switched Mode
Powersupply.
By placeing the Load in the PSU's Powersupply Line the Current through
the load is modulated. The DC Content is negated by the Push-pull
arrangement of the Switched mode Powersupply.
As the current-draw of the SMPS is directly proportional to the Current
flowing through the Valve - voiala we do not have a CONVENTIONAL OUTPUT
TRANSFORMER.
We still have a Transformer in the direct audio-circuit, now aided in
it's nefarious deeds by a bunch of Silicon.
I admit to never have heard a Berning "OTL" Amplifier but I find the
marketing claims misleading.
One could argue that his Amplifier combines a Class D Solid State
Amplifier with a Vaccuum Tube Amplifier.
>Has anybody heard these things?
I remeber Lynn Olson commenting on them (and I do not rember too
flattering comments either).
>Has anyone tried to play with the technology ideas?
I looked at it as said and instantly disliked the approach.
>What stops this idea making the OPT obsolete?
Because it does not work anywhere near as good as advertised maybe?
>(again)...... Should the SE eXperimenter be looking into this?
If you are happy dealing with high-power and high frequency Switched
Mode Supplies - sure.
>Or is there an Achilles' heel? Either technically, or sonically?
Technically, I'd say it is an wafull cludge to not eliminate a Output
transformer.
It is also VERY difficult to implement such a Switched Mode PSU with
perfect Square-waves at 200kHz and perfect symetry.
Unless this is observed the "Output Transformer Switched Powersupply"
will actually intermodulate with the signal and introduce significant
distortion.
As for the sonics, 200kHz is somewhat low for my taste to avoid
Intermodulation with the Signal. The result of IM with RF is a hard
bright and gritty sound often with substantial Sibilance where non
should be.
As Lynn what he heard....
>And if anyone can explain the principle in less quasi-patent-
>conscious language so even I can understand it, it would be great.
Hope the above was reasonably clear and concise.... It's the best I can
do.
Kind regards Thorsten.
======================================
e-mail:
Thorsten@tnt-audio.com
Visit TNT-Audio on the Web - the only advertising
free audio web-zine.
http://www.tnt-audio.com
======================================
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
=========================================================================
From: "Lynn T. Olson" <lynno@teleport.com>
Subject: Re: Berning's Zero Hysteresis Amp
Date: Wed, 21 Oct 1998 15:17:36 -0700
Source: Sound Digest Archive v01.n463
>One could argue that his Amplifier combines a Class D Solid State
>Amplifier with a Vaccuum Tube Amplifier.
I had a chat with David Berning and that's exactly the impression I
received. I was surprised by the description. Class D amplifiers are
notoriously sensitive to reactive loads, and as a speaker designer, I know
speakers are real dogs as far as impedance is concerned. I now feel the
best speakers are the most reactive, and it's the *amplifiers* job to
accept this as best it can.
>I remember Lynn Olson commenting on them (and I do not remember too
>flattering comments either).
I only listened briefly at the CES in the Westrex room. The only way to
audition the new WE300B in that room was the Berning amp and a Cary amp
that used the 300B as a driver for a 211 or 845, I don't remember which.
The Berning was playing through audiophile speakers, and it sounded
audiophile, just like the EAR V20 (the one with 20 12AX7's) at the VSAC
show.
It would be interesting to compare a modern Class D like the Spectron to
the Berning amp ... both are Class D, after all, but with an admitted 20:1
power difference.
Lynn Olson
E-mail: lynno@teleport.com
Ariel Speaker Page: http://www.teleport.com/~lynno/Ariel.htm
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@roads.sa.gov.au>
Subject: RE: Berning's Zero Hysteresis Amp
Date: Thu, 22 Oct 1998 14:47:03 +0930
Source: Sound Digest Archive v01.n463
Thanks Jean-Michel, Thorsten and Lynn for all the interesting discussion.
Now that I grasp it a bit better, I have to say that it doesn't interest me
much at this stage. I am quite stretched enough with standard class A triode
stuff for now.
Grant
> ----------
> From: Le Cleac'h J.-M.[SMTP:lecleach@cgi.ensmp.fr]
<snip>
> The so called "new technology" used in that amplifier is used from long
> times in SS audio amplifiers.
> I remember a Sony TAF08 or something like that, SS amplifier that used
> that
> technology.
> I used to listen to that marvel of technology but for the benefit of the
> Joelist I prefer not to give my listening impressions...
>
> BTW It seems to me that the hysterisis argument is flawed in their text.
> The hysterisis of an OPT leads mainly to a change of phase in the signal.
> Nothing hurts there.
>
>
>
> ----------
> From: T. Loesch[SMTP:ezee_e@hotmail.com]
>
> Here is a condensed and simplified description of the Principle:
>
> It appears that Mr. Berning uses a Switched Powersupply at 200kHz
> (seemingly in Push-Pull) to provide a rectified but UNSMOOTHED Supply to
> the Valves in question. This Voltage is stepped up by a TRANSFORMER to
> provide a HT high enough for the Valves in question.
>
> So the Output valve is effectively fed by 200kHz Square-Waves.
>
> The Valve(s) in turn modulate the Current Drawn by the Switched Mode
> Powersupply.
>
> By placeing the Load in the PSU's Powersupply Line the Current through
> the load is modulated. The DC Content is negated by the Push-pull
> arrangement of the Switched mode Powersupply.
>
> As the current-draw of the SMPS is directly proportional to the Current
> flowing through the Valve - voiala we do not have a CONVENTIONAL OUTPUT
> TRANSFORMER.
>
> We still have a Transformer in the direct audio-circuit, now aided in
> it's nefarious deeds by a bunch of Silicon.
>
> I admit to never have heard a Berning "OTL" Amplifier but I find the
> marketing claims misleading.
>
> One could argue that his Amplifier combines a Class D Solid State
> Amplifier with a Vaccuum Tube Amplifier.
....I looked at it as said and instantly disliked the approach.
...Technically, I'd say it is an awfull cludge to not eliminate a
Output
> transformer.
>
> It is also VERY difficult to implement such a Switched Mode PSU with
> perfect Square-waves at 200kHz and perfect symetry.
>
>
>
>
> ----------
> From: Lynn T. Olson[SMTP:lynno@teleport.com]
>
> >One could argue that his Amplifier combines a Class D Solid State
> >Amplifier with a Vaccuum Tube Amplifier.
>
> I had a chat with David Berning and that's exactly the impression I
> received. I was surprised by the description. Class D amplifiers are
> notoriously sensitive to reactive loads, and as a speaker designer, I know
> speakers are real dogs as far as impedance is concerned. I now feel the
> best speakers are the most reactive, and it's the *amplifiers* job to
> accept this as best it can.
>
> I only listened briefly.....
The Berning was playing through audiophile speakers, and it sounded
> audiophile, just like the EAR V20 (the one with 20 12AX7's) at the VSAC
> show.
>
> It would be interesting to compare a modern Class D like the Spectron to
> the Berning amp ... both are Class D, after all, but with an admitted 20:1
> power difference.
=========================================================================
From: Thomas Danley <Tom@ppci.com>
Subject: Re: Berning's Zero Hysteresis Amp
Date: Thu, 22 Oct 1998 09:15:26 -0500
Source: Sound Digest Archive v01.n464
Hi
While PWM is the currently most popular way to have a high efficiency output
stage, it is not the only way and given the implied slew rates associated with
high voltage square waves, I would bet that is not what is being done in the
output stage.
There is/was an area where home built tube equipment was on a scale that dwarfs
audio construction, that is "Ham Radio". Many of the audio output tubes used
today started life
as transmitting tubes and it is usually no problem to operate any tube at a few
MHZ.
In a transmitter, the output device is generally on during less than half the
output wave in an operation called class "C".
A resonant tank circuit is driven by the output device and is what provides the
sine wave shape and in operation called SSB (single side band), the system must
be quite linear in order not to have an excessive harmonic spectrum, so the
tubes developed for SSB are especially linear (like 6146 etc.) and also work
well in audio.
While class "C" is less efficient than PWM can be, it is more efficient than
class A, AB, B
operation. To produce audio this way, you amplitude modulate the rf carrier with
two modulators (say 1 MHZ) and drive a pair of tank circuits which each drive an
RF step-down transformer. The output of each transformer has a very high speed
rectifier and each transformer section produces the positive or negative voltage
(the audio signal increases one polarity while reducing the other) . The raw
output voltage could be fed to a low pass filter to attenuate the 2 MHz supply
ripple. Even a simple two pole filter (12 dB/oct) would reduce the RF carrier
by 72 dB at 30 kHz. The stages could be effectively set up to be Class "A" "B"
etc. depending on the no signal current.
I don't know if this is how they did it but it is one way to do the job.
Best Regards,
Tom Danley
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: Berning's Zero Hysteresis Amp
Date: Thu, 22 Oct 1998 09:37:35 -0400
Source: Sound Digest Archive v01.n464
Lynn T. Olson wrote:
> >One could argue that his Amplifier combines a Class D Solid State
> >Amplifier with a Vaccuum Tube Amplifier.
>
> I had a chat with David Berning and that's exactly the impression I
> received. I was surprised by the description. Class D amplifiers are
> notoriously sensitive to reactive loads, and as a speaker designer, I know
> speakers are real dogs as far as impedance is concerned. I now feel the
> best speakers are the most reactive, and it's the *amplifiers* job to
> accept this as best it can.
Class-D amplifiers need not be load sensitive.
This potential problem stems from the need to have an L-C lowpass filter on
the amp output to suppress the switching waveform, which will be several
hundred kHz or higher. If this L-C filter is not terminated in its
characteristic impedance, then frequency response ripple will result. In fact,
quite a bit of high frequency peaking may be present with "most" moving coil
loudspeakers, since they're inductive at high frequencies.
It is possible, however, to enclose the L-C filter inside the feedback loop.
After all, switchmode power supply designers do this all the time. However,
you need to be very careful that the Class-D amp remains stable into an open
circuit as well as a resistive load. There are several patents discussing
state-space solutions to this problem. Personally, I just use a variant of the
"Type 3" error amplifier familiar to switching power supply designers. For
example, I'm able to get less than 1dB of response error at 20kHz when going
from open circuit to resistive load, when switching at 300kHz, using this
technique. (No flames about "needing" NFB: this is my day job.)
Note that the TacT (?) amp, being purely "digital", does not have the benefit
of such analog feedback for load stabilization, and high frequency response
peaking will result. It is possible, though, to add a Zobel network on the
output. This helps, but it's not a universal solution, and capacitor failure
can easily result. Others use techniques that push the switching frequency
higher (Crown) or allow more of the high frequency energy to get through.
JL
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: Berning's Zero Hysteresis Amp
Date: Fri, 23 Oct 1998 02:47:22 PDT
Source: Sound Digest Archive v01.n465
Hi there,
>I would bet that is not what is being done in the
>output stage.
Quite correct. The Amp is not PWM.
It is a SMPS with the Load connected into the Low-Voltage Power-Input to
the SMPS with suitable arrangements (PP) to eliminate the DC-Component.
The Voltage to the Valve(s) is rectified but not smoothed.
As a result the Current Drawn by the SMPS is directly modulated by the
Current through the valve.
Kind regards Thorsten.
======================================
e-mail:
Thorsten@tnt-audio.com
Visit TNT-Audio on the Web - the only advertising
free audio web-zine.
http://www.tnt-audio.com
======================================
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: Berning's Zero Hysteresis Amp
Date: Fri, 23 Oct 1998 10:17:10 PDT
Source: Sound Digest Archive v01.n465
Hi there,
>Since my work as an EMC engineer I focus on the combination of
>both audio and EMC (as you might notice once and a while)
Indeed, one does. How'z da trazlation of the Audio & Technik Article on
EMI and measures against it comming along? I really liked that one and
I'm sure a lot of Joe's could benefit....
>I still do not believe that an amplifier made with such high
>RF energy in its direct vicinity will produce proper sound.
I have tried to abstain mostly from judgements of the value of the
invention. I did however say that it would not be difficult for me to
build such an Amp. I have not....
I think if the HT Diodes would use suitable Schottky Stacks (to get the
Voltage) and if the Square-Waves AFTER the Transformer where REALLY
SQUARE and if they could be kept to ABSOLUTE SYMMETRICAL (1 : 10000 at
least) between the Two halves of the SMPS, THEN I would have little
qualms about the sound....
Considering the not insubstantial problems of producing real
square-waves at 200kHz, the fact the to get 500V +B from Schottkies
amkes for quite a few of the little critters and never mind getting the
thing to behave truely symmetric, I suppose the real design will have
substantial technical flaws which might or might not be audible.
I must note that Dr. Gizmo had a "print-orgasm" about the Berning Amp
and that Dick Olsher apparently likes them. I on principle do not.
If Mr. Berning would send me one to evaluate and write about and if the
Amp is anywhere near as good as he claims I might like it too....
>All amplifiers based on PWM or the above described did not
>convince me (untill now)
Agreed. I have heard the TACT and while not bad I was not very much
impressed either. Slick volume Control though....
>Why go this difficult way ?
Unique Selling Point?
Kind regards Thorsten.
======================================
e-mail:
Thorsten@tnt-audio.com
Visit TNT-Audio on the Web - the only advertising
free audio web-zine.
http://www.tnt-audio.com
======================================
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: Berning's Zero Hysteresis Amp
Date: Fri, 23 Oct 1998 18:53:18 +0200
Source: Sound Digest Archive v01.n465
Thorsen,
Thanks for nuances. Now my 2 cents
Since my work as an EMC engineer I focus on the combination of both audio
and EMC (as you might notice once and a while)
I still do not believe that an amplifier made with such high RF energy in
its direct vicinity will produce proper sound. All amplifiers based on PWM
or the above described did not convince me (untill now)
Why go this difficult way ?
Guido
At 02:47 23-10-98 PDT, T. Loesch wrote:
>Hi there,
>
>>I would bet that is not what is being done in the
>>output stage.
>
>Quite correct. The Amp is not PWM.
>
>It is a SMPS with the Load connected into the Low-Voltage Power-Input to
>the SMPS with suitable arrangements (PP) to eliminate the DC-Component.
>
>The Voltage to the Valve(s) is rectified but not smoothed.
>
>As a result the Current Drawn by the SMPS is directly modulated by the
>Current through the valve.
>
>Kind regards Thorsten.
>
>======================================
>e-mail:
>Thorsten@tnt-audio.com
>
>Visit TNT-Audio on the Web - the only advertising
>free audio web-zine.
>
>http://www.tnt-audio.com
>======================================
>
>
>______________________________________________________
>Get Your Private, Free Email at http://www.hotmail.com
>
>
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: Berning's Zero Hysteresis Amp
Date: Sat, 24 Oct 1998 18:57:20 +0200
Source: Sound Digest Archive v01.n466
At 10:17 23-10-98 PDT, T. Loesch wrote:
>Hi there,
Hi
>>Since my work as an EMC engineer I focus on the combination of
>>both audio and EMC (as you might notice once and a while)
>
>Indeed, one does. How'z da trazlation of the Audio & Technik Article on
>EMI and measures against it comming along? I really liked that one and
>I'm sure a lot of Joe's could benefit....
Well, I still intend to translate that. Lack of time is my biggest pain in
the ass. To quote someone among us: "so many tubes, so little time"
Thanks though for your kind words
>>I still do not believe that an amplifier made with such high
>>RF energy in its direct vicinity will produce proper sound.
>
>I have tried to abstain mostly from judgements of the value of the
>invention. I did however say that it would not be difficult for me to
>build such an Amp. I have not....
>
>I think if the HT Diodes would use suitable Schottky Stacks (to get the
>Voltage) and if the Square-Waves AFTER the Transformer where REALLY
>SQUARE and if they could be kept to ABSOLUTE SYMMETRICAL (1 : 10000 at
>least) between the Two halves of the SMPS, THEN I would have little
>qualms about the sound....
If......
>Considering the not insubstantial problems of producing real
>square-waves at 200kHz, the fact the to get 500V +B from Schottkies
>amkes for quite a few of the little critters and never mind getting the
>thing to behave truely symmetric, I suppose the real design will have
>substantial technical flaws which might or might not be audible.
>
>I must note that Dr. Gizmo had a "print-orgasm" about the Berning Amp
>and that Dick Olsher apparently likes them. I on principle do not.
>
>If Mr. Berning would send me one to evaluate and write about and if the
>Amp is anywhere near as good as he claims I might like it too....
>
>>All amplifiers based on PWM or the above described did not
>>convince me (untill now)
>
>Agreed. I have heard the TACT and while not bad I was not very much
>impressed either. Slick volume Control though....
>
>>Why go this difficult way ?
>
>Unique Selling Point?
Ya, but no additional value for sound. Sometimes electronics and its'
potential is used to create products that might be impressive from the
technical approac, but why turn the whole upside down ? I mean what is the
goal ?
Good sound or clever electronics ?
The latter is OK but does not guarantee good sound
The same holds for tubes. They are only means, no goals. if I understand
transistors better I'll go for transistors !
regards,
=
Guido
>Kind regards Thorsten.
>
>======================================
>e-mail:
>Thorsten@tnt-audio.com
>
>Visit TNT-Audio on the Web - the only advertising
>free audio web-zine.
>
>http://www.tnt-audio.com
>======================================
>
>
>______________________________________________________
>Get Your Private, Free Email at http://www.hotmail.com
>
>
=========================================================================
From: trs@carlsmith.com
Subject: Berning's Zero Hysteresis Amp -Reply
Date: Wed, 21 Oct 1998 9:54:27 -1000
Source: Sound Digest Archive v01.n463
Grant-
Like you, I am very interested in having some Joe with
switching power supply expertise analyze this thing and tell
us whether the apparent "free lunch" of an SE amp with no
OPT can be a reality. David Berning has done a lot of
interesting and iconoclastic tube stuff in the past, so I got a
copy of the Berning patent but quickly realized I was in way
over my head. The various iterations of the concept shown in
the patent all use typical switching power supply elements
like mosfets and a toroidal transformer, but the patent claims
themselves argue for a radical new implementation of the SE
tube amp concept by eliminating the inductance of the OPT.
The latest issue of Positive Feedback has a typically
over-the-top puff piece on the amp by Harvey Rosenberg and
some commentary by an editor who seemingly did not
understand the circuit, followed by a response from David
Berning that attempted to explain the circuit but still left me
hanging. I'll send you a copy if you give me your mailing
address, but let's hope that some of the List's high-speed ss
gurus weigh in on the subject in a manner we can all
understand.
Regards, Tom Sylvester trs@carlsmith.com
>>> "Grant.Sellek@roads.sa.gov.au" 10/21/98 04:16am >>>
Hi All,
I don't recall any discussion on Joenet of David Berning's
Zero Hysteresis
amps. Has anyone had a look at these?
http://www.milbert.com/db/zh270.htm
http://www.milbert.com/db/SiegBroch.htm
http://www.milbert.com/db/dbzhas.htm
The idea is to replace the OPT with a different kind of
impedance
transformer, using switching power supply technology to
convert the audio
impedance with an RF carrier. Berning's paper (the last of the
three links
above) considers a 6L6 and concludes "In an audio
application, the tube
behaves as if it is driving a 4k ohm speaker (the impedance
conversion ratio
goes as the square of the turns ratio), and the speaker acts
and sounds as
if it is being driven by a 0.6 ohm triode."
The curve traces on the output side of the Berning
impedance transformer are
very impressive for their lack of hysteresis. The Siegfried amp
is a very
impressive looking 12W SE amp with no audio NFB using
the SV811-10 or
WE300B. US$6000-$7000 though.
Has anybody heard these things? Has anyone tried to play
with the technology
ideas? What stops this idea making the OPT obsolete?
(again)...... Should
the SE eXperimenter be looking into this?
Or is there an Achilles' heel? Either technically, or sonically?
And if anyone can explain the principle in less
quasi-patent-conscious
language so even I can understand it, it would be great.
Grant
Grant Sellek
Adelaide, Australia
grant.sellek@roads.sa.gov.au
=========================================================================
From: "Jon Lane" <jhlane@email.msn.com>
Subject: Best amps
Date: Sat, 11 Jul 1998 16:56:38 -0700
Source: Sound Digest Archive v01.n339
> The only problem that I have in spending $900 on outputs is that, as an
> inveterate DIY-amp guy, I know I'd be wanting to build a
> different amp with
> a different tube pretty damn soon. Then the Westerns would have to go in
> the closet with the VV30s. :-) - Pat
>
> Pat Currie (tubesguy@execpc.com)
I'm about to take delivery of two matched pairs of the WE's. Having waited
for over a decade to find some, I decided to just buy them new. The point
is, I fully expect to use these for the rest of my life. Listening to
music. Sure, there will undoubtedly be a number of changes to the input and
drivers over time, and the LS57's may some day be replaced (I hear you Pat),
but the essential output amp will remain: pp 300b.
I got into DIY audio as a means to hear MUSIC. Great music on a (relative)
budget. Even with five figures in the system, I know I can't begin to find
this kind of enjoyment with three times that figure spent on commercial
alternatives.
Barring some unforeseen and uncontrollable urge to rip it all up and start
again, I have to believe that there are tried and proven Joe topologies for
driving pp 300b's that won't leave me wanting to do that. Perhaps Lynn's
latest schematic. I plan to use dedicated supplies for all stages and will
probably use a parafed transformer splitter/driver, but can anyone suggest a
95% solution for the balance of the circuit that compliments the WE tubes?
What are the best contenders?
Been on the List for a month--would appreciate it.
Jon
=========================================================================
From: "Lynn T. Olson" <lynno@teleport.com>
Subject: Re: Best amps
Date: Sat, 11 Jul 1998 17:21:49 -0700
Source: Sound Digest Archive v01.n339
>Barring some unforeseen and uncontrollable urge to rip it all up and start
>again, I have to believe that there are tried and proven Joe topologies for
>driving pp 300b's that won't leave me wanting to do that. Perhaps Lynn's
>latest schematic. I plan to use dedicated supplies for all stages and will
>probably use a parafed transformer splitter/driver, but can anyone suggest a
>95% solution for the balance of the circuit that compliments the WE tubes?
>What are the best contenders?
The latest thought-piece is at:
http://www.teleport.com/~lynno/Mark_IIB.gif
Might actually get around to building it sometime after VSAC. For those
tuning in late, the previous gedanken is at:
http://www.teleport.com/~lynno/Mark_II.gif
and the one that sits in my living room (and paid a visit to Poulsbo) is at:
http://www.teleport.com/~lynno/IT-Triode-Amp.gif
Lynn T. Olson
E-mail: lynno@teleport.com
Ariel Speaker Page: http://www.teleport.com/~lynno/Ariel.htm
=========================================================================
From: Steve Van Osdell <svanos@toast.net>
Subject: Re: Best Bookshelf Speaker
Date: Thu, 19 Feb 1998 08:02:32 -0600
Source: Sound Digest Archive v01.n196
Radio Shack has the big Lineaum bookshelf speakers on sale until the 22nd.
They are 50% off! These are the bigger ones with the 8" woofer. Reg.
$200, reduced to $100. I even used my 10% customer appreciation card I'd
been saving for even better price. Don't know what is the efficiency, but
they sound really good.
Thanks, Steve
=========================================================================
From: Chris Galbraith <chrisg@ducker.com>
Subject: Best bookshelf speak for the office?? Any advice welcome!
Date: Wed, 18 Feb 1998 17:18:52 -0500
Source: Sound Digest Archive v01.n196
Gang,
Sorry a little off topic--after cleaning 300lbs+ garbage out of my
shelves (no kidding), I want to bring in a little 6BQ5 p-p or something,
maybe even mono into my (small) office--vots or cornerhorn won't fit.
Any recommendations on 90dB or so bookshelfs? Cheap is good--thanks for
any help!
=========================================================================
From: David Home <tubehead@vcn.bc.ca>
Subject: Re: Best bookshelf speak for the office?? Any advice welcome!
Date: Wed, 18 Feb 1998 23:02:23 -0800 (PST)
Source: Sound Digest Archive v01.n196
PSB ALPHAs. Got a pair to go with the Eico HF20 I got my sister-in-law
into year. About $160US a pair, small and rated at 90 dB. Sound not too
bad as long as you don't push them really hard. I don't know how you
will get any work done once there is a tube stereo in your office.
"Hmm, should I do this sales spreadsheet or groove to some Miles for
the afternoon..."
Regards, David
On Wed, 18 Feb 1998, Chris Galbraith wrote:
> Gang,
> Sorry a little off topic--after cleaning 300lbs+ garbage out of my
> shelves (no kidding), I want to bring in a little 6BQ5 p-p or something,
> maybe even mono into my (small) office--vots or cornerhorn won't fit.
>
> Any recommendations on 90dB or so bookshelfs? Cheap is good--thanks for
> any help!
>
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: Best bookshelf speak for the office?? Any advice welcome!
Date: Thu, 19 Feb 98 11:23:56 -0500
Source: Sound Digest Archive v01.n197
Chris,
The best monitor that I have had luck with is the ProAc Tablette
Signature 50. It claims 90dB but I would say more like 88dB.
We set up our room at CES97 with a Junior and a pair of Tabs and we had
people comming in saying that it just sounded GREAT.
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: Kalman Rubinson <rubinsnk@is2.nyu.edu>
Subject: Re: Best DAC for the buck !!!!!!!!!!!!
Date: Sun, 21 Dec 1997 12:34:15 -0500 (EST)
Source: Sound Digest Archive v01.n139
On Sun, 21 Dec 1997, dror sofer wrote:
> I am looking for a $ 100 +- price (new) DAC maybe audio alchemy,
> Is there anything for this price.
>
> Any suggestions?
>
Since AA is dead, there is nothing 'new' in that price
range. Used is your best bet.
Kal
>
> D
>
=========================================================================
From: DrorS@vcon.co.il (dror sofer)
Subject: Best DAC for the buck !!!!!!!!!!!!
Date: Sun, 21 Dec 1997 15:21:57 +0200
Source: Sound Digest Archive v01.n139
Hi all
I am looking for a $ 100 +- price (new) DAC maybe audio alchemy,
Is there anything for this price.
Any suggestions?
D
=========================================================================
From: "Paul Kubicz" <pkube@umich.edu>
Subject: Best sounding 24/96 discs
Date: Tue, 15 Dec 1998 13:08:40 -0500
Source: Sound Digest Archive v01.n540
Hello,
With all of the recent talk of 24/96, I was hoping I could get suggestions
on the best-sounding discs. (I'm a new subscriber;I hope this wasn't covered
recently.) Since I'm evaluating primarily the technology, I'm more
interested in sound than performance, although I do prefer classical to
jazz.
Ideally the disc would have identical 16/44.1 performances for A/B
comparisons (though I imagine this is a format rather than a disc-to-disc
feature).
Thanks!
=========================================================================
From: Kalman Rubinson <kr4@is2.nyu.edu>
Subject: Re: Best sounding 24/96 discs
Date: Tue, 15 Dec 1998 14:13:57 -0500 (EST)
Source: Sound Digest Archive v01.n540
On Tue, 15 Dec 1998, Paul Kubicz wrote:
> With all of the recent talk of 24/96, I was hoping I could get suggestions
> on the best-sounding discs. (I'm a new subscriber;I hope this wasn't covered
> recently.) Since I'm evaluating primarily the technology, I'm more
> interested in sound than performance, although I do prefer classical to
> jazz.
>
> Ideally the disc would have identical 16/44.1 performances for A/B
> comparisons (though I imagine this is a format rather than a disc-to-disc
> feature).
The problem with A/B comparisons, you will quickly find, is
the source. Most of the Classic DADs is that, although the
CD and the 24/96 (DVD) were digitized from the same analog
master tape, they were digitized and processed on different
machines by different people. That said, the Muddy Waters
'Folk Singer,' Buddy Guy 'Mr. Lucky,' Johanos' 'Rachmaninoff
Symphonic Dances' and the 'Glory' soundtrack are pretty good.
From Chesky, try David Chesky's Three Psalms, Also the
Olatunji, the Sarah K or Livingston Taylor if you like
that sort of stuff.
OTOH, I haven't heard a really bad one yet. But, then, again
I still haven't gotten through them all.
Kal
=========================================================================
From: AnnaLogg@aol.com
Subject: Re: Best sounding 24/96 discs
Date: Tue, 15 Dec 1998 16:34:14 EST
Source: Sound Digest Archive v01.n540
Hi Paul,
You might find my article about the New Jersey Audio Society meeting where
Classic Record's Mike Hobson gave the kind of comparative demo you're
wondering about -- however this was a comparison of three media -- in addition
to the DAD and the regular CD, we also compared them against the same source
material cut on vinyl at 45 rpm. Most of it relates the members' reactions to
the three discs, and Kal is absolutely right about the fact that it is not a
"true" comparison with *all* things being equal. However, I thought it was
fair in terms of what is available to judge in the marketplace, so given this
caveat you may find the comments interesting.
http://www.tnt-audio.com/sorgenti/2496e.html
Incidentally, Mike Hobson himself also recommends the Chesky "sampler."
Best,
Valerie Ann(a)
=========================================================================
From: Kalman Rubinson <kr4@is2.nyu.edu>
Subject: Re: Best sounding 24/96 discs
Date: Tue, 15 Dec 1998 18:07:35 -0500 (EST)
Source: Sound Digest Archive v01.n540
On Tue, 15 Dec 1998 AnnaLogg@aol.com wrote:
> Incidentally, Mike Hobson himself also recommends the Chesky "sampler."
Let me point out that the Chesky sampler and individual
releases were originally recorded at 24/96 digital while the
Classic discs were transferred (very well) from analog
master tapes by Kevin Halverson of Muse. Thus, the regular
Chesky CDs are downsamples from the same source and afford a
better comparison of the media, if that's your aim. The
Classic releases have been released on CD by others and the
comparison of the media is less direct here.
Kal
=========================================================================
From: Kalman Rubinson <kr4@is2.nyu.edu>
Subject: Re: Best sounding 24/96 discs
Date: Wed, 16 Dec 1998 18:42:22 -0500 (EST)
Source: Sound Digest Archive v01.n542
On Wed, 16 Dec 1998, J. Gordon Rankin wrote:
> I have all the Cheskies and the DAD are on the way. I think what sums up
> the experience here is that with the increase in information comes
> increase levels of preformance. Either way will be a big increase in
> preformance over the std CD format. I have hardly listened to anything
> else since I got my DVD player and my 24/96 dac working.
All we need now are MORE!
Kal
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: Best sounding 24/96 discs
Date: Wed, 16 Dec 98 15:49:12 -0500
Source: Sound Digest Archive v01.n542
Paul, Kal and Anna
I have all the Cheskies and the DAD are on the way. I think what sums up
the experience here is that with the increase in information comes
increase levels of preformance. Either way will be a big increase in
preformance over the std CD format. I have hardly listened to anything
else since I got my DVD player and my 24/96 dac working.
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.wavelengthaudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "Aaron Bohnen" <bohnen@mail.unixg.ubc.ca>
Subject: Best wishes to one and all...
Date: Thu, 24 Dec 1998 12:15:24 +0000
Source: Sound Digest Archive v01.n551
Hello friends one and all,
I would like to extend my warmest and kindest greetings to all of you.
I sincerely hope this Christmas finds each of you and your families
united, happy and content.
To my SET Joenet friends, may your DHTs' golden glow warm you...
To my BMW Digest friends, may your machines run true this season...
To my Nakamichi friends, may your decks tape and play fine music...
To my Bass and DIY loudspeaker friends, may your bass be deep, your
midrange transparent and your highs clear and sparkling...
To my Heathkit friends, may your vintage equipment serve you well for
yet another year...
Blessings to each of you.
Sincerely,
Aaron
___________________________________________________________
Aaron Bohnen email: bohnen@unixg.ubc.ca
- -Ph.D. Student, Civil Engineering Department, U.B.C.
- -Technicraft Engineering Services
=========================================================================
From: Hartmut Quaschik <Hartmut.Quaschik@bku.db.de>
Subject: Betr.: Re: Fun little PP 6B4 amp
Date: 02 Dec 1998 15:55:21 +0100
Source: Sound Digest Archive v01.n514
Torbjoern,
I have seen your Kaneda power amp on Dunker's picture pages on the web and like to know
which Kaneda power amp you have built (how much power, from MJ or from L'Audiophile
magazin, which transistors, ...) and how it does compare against other power amps.
regards,
Hartmut from Munich
Hartmut Quaschik
SBS GmbH & Co OHG, München
DZP 1 / Frankfurt Projekt RPM
Tel. (DB) 069/265-27111 / (SBS) 089/636-52205/mobil:0170/2278943
=========================================================================
From: Hartmut Quaschik <Hartmut.Quaschik@bku.db.de>
Subject: Betr.: Re: Le Tube
Date: 30 Nov 1998 17:53:49 +0100
Source: Sound Digest Archive v01.n509
>> The input stage was Gnded with: 47µF in parallell with 820ohms.
>> A series 1k5 from this parallel C+R to cathode.Anode load 301k, output
>> coupled via 0,47µf to 150k leak to Gnd. From top of this one, signal
>> goes to the last tube via 20kohm. From grid to Gnd on last tube also a
>> series connection of 10nF and 1kohm.(This forms, in conjunction
>> with the feedback, the passive 2k-something hf-cutoff.)
>An interesting URL about the Hiraga tube preamp (I didn't verify if it is
>the same as the one dicussed by Torbjųrn Lien) is at:
>http://www.infomaniak.ch/~bonavolt/fr/hiraga.htm
That Marantz/McIntosh style phono preamp with three halves of an ECC83 differs a lot
from the commercialised tube preamp "Le tube".
I had the chance to listen to a "Le tube" 8 years ago at home, a friend brought it for a
listenening evening, and I wasn't impressed at all.
The Kaneda preamp (solid state) was much better that time.
regards,
Hartmut
=========================================================================
From: Hartmut Quaschik <Hartmut.Quaschik@bku.db.de>
Subject: Betr.: Re: Lowther front horns
Date: 03 Dec 1998 09:13:52 +0100
Source: Sound Digest Archive v01.n516
Gordon,
>Also what bass and treble units are you going to match with a mid that
>has some 107dB output?
you could use the Cabasse hi-end Pro-gear with front loaded
Cabasse woofers, have a look at http://www.cabasse.com
regards,
Hartmut
Hartmut Quaschik
SBS GmbH & Co OHG, München
DZP 1 / Frankfurt Projekt RPM
Tel. (DB) 069/265-27111 / (SBS) 089/636-52205/mobil:0170/2278943
=========================================================================
From: Hartmut Quaschik <Hartmut.Quaschik@bku.db.de>
Subject: Betr.: Re: Reverse RIAA
Date: 26 Nov 1998 17:57:35 +0100
Source: Sound Digest Archive v01.n505
The inverse RIAA is passive and its quality/accuracy is dependent on passive
electronic parts (only). As it consists only of the network itself, it should be not a
problem to do it right. OK, you must do use the right input/output impedance, but
that's all. But if you feed Allen Wright's inverse RIAA with a normally low output
function generator and connect the low impedance output of the network with
a 47K input impedance RIAA stage, you won't have any problem.
A RIAA phono stage normally has a lot of gain, and if you have an active equalisation,
you might not have enough gain for accurate bass frequency response, and you
may have additional effects from the active parts in the circuit, be it transistors,
be it tubes.
Even if you have a passive RIAA equalisation, load resistors and input (Miller)
capacities and output impedances between the gain stages (if split RIAA)
all do play a role and may corrupt your calculated frequency response.
regards,
Hartmut from Munich, now in Frankfurt
Kal wrote:
On Thu, 26 Nov 1998, Lance Dow wrote:
> They're not assumed to be accurate, they're made accurate.
Fine. Your procedure ensures amplitude vs. frequency
accuracy just fine.
> If you now feed this signal into your phono stage, the
> output of that should be flat with frequency. You then
> tweak the values of your phono stage network for the
> flattest possible response.
Why not simply do the same with the RIAA stage directly? It
doesn't save much time (unless you build many RIAAs) to
build a standard when you can apply the same (inverse) test
to the DUT.
> Since a square wave is the fundamental plus all the odd harmonics, this
> would be much quicker than sweeping a sine wave, provided you know how to
> recognise the changes in wave shape due to frequency response variations.
But it also assumes that the inverse RIAA is perfect in all
unmeasured ways as well.
persönliche Kategorien:
Hartmut Quaschik
SBS GmbH & Co OHG, München
DZP 1 / Frankfurt Projekt RPM
Tel. (DB) 069/265-27111 / (SBS) 089/636-52205
=========================================================================
From: Hartmut Quaschik <Hartmut.Quaschik@bku.db.de>
Subject: Betr.: Shocking MR-71 Performance
Date: 15 Dec 1998 10:27:51 +0100
Source: Sound Digest Archive v01.n539
Folks,
I had been shocked by Mac-Tuners MR71 and MR67, too. Remedy was to unsolder that cap,
that takes the capacitive half of the line voltage to chassis ground.
It is easily identifyable, as it is directly attached to the
line cord, where it comes into the chassis. It is a big ceramic cap with three legs.
Two legs go to the line voltage, one to chassis ground.
regards,
Hartmut
=========================================================================
From: Douglas Purl <dcp@selway.umt.edu>
Subject: Re: Better Lowther?
Date: Tue, 27 Oct 1998 15:35:21 -0700 (MST)
Source: Sound Digest Archive v01.n470
On Tue, 27 Oct 1998, Bert Doppenberg wrote:
> Hi all,
>
> What is this about a better Lowther? Better then wich type? Or totaly
> different speakers?
>
> Anybody who is seeking for a better Lowther, did they already listened to
> the PM5,
> PM4 or DX4 units in a suitable enclosure??
>
> Or are we talking about the C-series which should be improved?
Bert, I am trying to get a handle on this Lowther mystique, not precisely
because I am interested in Lowthers, but because I trying to understand
what comprises the constant core of qualities that draw people to this
amazingly durable ante-diluvian technology. I would much enjoy to read a
detailed discussion of the differences and variations you allude to.
The discussion has already proved valuable to me, not just for the care
with which people have chronicled their own Lowther experiences, good and
bad, but also for Tom Danley's wonderful prolegomenon to the design of a
single-driver cone loudspeaker.
Doug Purl
=========================================================================
From: "Bert Doppenberg" <lowther@wxs.nl>
Subject: Better Lowther?
Date: Tue, 27 Oct 1998 21:42:43 +0100
Source: Sound Digest Archive v01.n470
Hi all,
What is this about a better Lowther? Better then wich type? Or totaly
different speakers?
Anybody who is seeking for a better Lowther, did they already listened to
the PM5,
PM4 or DX4 units in a suitable enclosure??
Or are we talking about the C-series which should be improved?
Regards,
Bert
- ------
BD-Design -- Ontwikkeling en Distributie van geluidssytemen
E-mail: bd-design@vt52.com http://www.vt52.com/bd-design
Tel./Fax: (0341) 254500 Mobiel: (06) 51242990
Bert Doppenberg - Lowther Club Holland
E-mail: lowther@wxs.nl http://home.wxs.nl/~lowther/home.htm
=========================================================================
From: peterca@ento.csiro.au
Subject: Re: Better Lowther?
Date: Wed, 28 Oct 1998 10:22:06 +1100 (EST)
Source: Sound Digest Archive v01.n470
>On Tue, 27 Oct 1998, Bert Doppenberg wrote:
>
>> Hi all,
>>
>> What is this about a better Lowther? Better then wich type? Or totaly
>> different speakers?
>>
>> Anybody who is seeking for a better Lowther, did they already listened to
>> the PM5,
>> PM4 or DX4 units in a suitable enclosure??
>>
>> Or are we talking about the C-series which should be improved?
>
>Bert, I am trying to get a handle on this Lowther mystique, not precisely
>because I am interested in Lowthers, but because I trying to understand
>what comprises the constant core of qualities that draw people to this
>amazingly durable ante-diluvian technology. I would much enjoy to read a
>detailed discussion of the differences and variations you allude to.
.......
>Doug Purl
The main thing that differs between models is the magnet. An article in
Klang und Ton 2/1993 shows waterfall plots for the cheaper ceramic maget
version of the PM6 and the more expensive alnico magnet version. The
resonances are better damped in the alnico version and people say it sounds
smoother to them. I'd say it is likely there is a causal link in there.
The same trend continues for the even beefier PM2.
Dr. Peter Campbell (peterca@ento.csiro.au)
Div. Entomology, C.S.I.R.O. Ph.61-2-62464053 or -62464158 (w)
Box 1700 Canberra A.C.T. 2601 61-2-62516213 (h)
Australia 61-2-62464173 (fax)
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: Better Lowther?
Date: Wed, 28 Oct 1998 07:09:33 -0500 (EST)
Source: Sound Digest Archive v01.n471
At 09:42 PM 10/27/98 +0100, Bert Doppenberg wrote:
>Hi all,
>
>What is this about a better Lowther? Better then wich type? Or totaly
>different speakers?
>
>Anybody who is seeking for a better Lowther, did they already listened to
>the PM5,
>PM4 or DX4 units in a suitable enclosure??
>
>Or are we talking about the C-series which should be improved?
>
>Regards,
>
>Bert
Can Bach's Advent Cantatas be reproduced correctly on Lowthers?
Thank you in advance,
David Klein
=========================================================================
From: "Bert Doppenberg" <lowther@wxs.nl>
Subject: Re: Better Lowther?
Date: Wed, 28 Oct 1998 09:13:54 +0100
Source: Sound Digest Archive v01.n471
Hi Johari,
>Now being such a new driver, do anyone know the suitable compression volume
>to use with the DX4 when designing a back-loaded horn for it?
The new DX4 isn't gone into production yet. There are several people
experimenting with them though.....
Calculating a back chamber isn't really possible and should be experimental
judget. The volume is depending on the lenght of the horn and the throat
area!. Best is to make the chamber too large and adjust the size that suits
(sounds) best!
Best regards,
Bert
- ------
BD-Design -- Ontwikkeling en Distributie van geluidssytemen
E-mail: bd-design@vt52.com http://www.vt52.com/bd-design
Tel./Fax: (0341) 254500 Mobiel: (06) 51242990
Bert Doppenberg - Lowther Club Holland
E-mail: lowther@wxs.nl http://home.wxs.nl/~lowther/home.htm
=========================================================================
From: "Johari Yip" <hfyip@pacific.net.sg>
Subject: Re: Better Lowther?
Date: Wed, 28 Oct 1998 09:42:59 +0800
Source: Sound Digest Archive v01.n471
- ----------
> From: Bert Doppenberg <lowther@wxs.nl>
> To: Joe's Net <sound@deliverator.io.com>
> Subject: Better Lowther?
> Date: Wednesday, October 28, 1998 4:42 AM
>
>
> Anybody who is seeking for a better Lowther, did they already listened to
> the PM5,
> PM4 or DX4 units in a suitable enclosure??
Now being such a new driver, do anyone know the suitable compression volume
to use with the DX4 when designing a back-loaded horn for it?
Thanks in advance
Johari
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: Better Lowther?
Date: Wed, 28 Oct 1998 13:11:50 -0500 (EST)
Source: Sound Digest Archive v01.n472
At 07:08 PM 10/28/98 +0100, evaguido wrote:
>At 07:09 28-10-98 -0500, David B. Klein wrote:
>>At 09:42 PM 10/27/98 +0100, Bert Doppenberg wrote:
>>>Hi all,
>>>
>>>What is this about a better Lowther? Better then wich type? Or totaly
>>>different speakers?
>>>
>>>Anybody who is seeking for a better Lowther, did they already listened to
>>>the PM5,
>>>PM4 or DX4 units in a suitable enclosure??
>>>
>>>Or are we talking about the C-series which should be improved?
>>>
>>>Regards,
>>>
>>>Bert
>>
>>Can Bach's Advent Cantatas be reproduced correctly on Lowthers?
>
>What is your definition of "correctly"
>
>Guido
>
>>Thank you in advance,
>>
>>David Klein
>>
Well, it seems to me the composer wrote these cantatas to be played on
direct radiating loudspeaker systems such as the Advents, hence the title of
the works in question ...
David
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: Better Lowther?
Date: Wed, 28 Oct 1998 13:24:37 -0500 (EST)
Source: Sound Digest Archive v01.n472
At 07:22 PM 10/28/98 +0100, evaguido wrote:
>>>>Can Bach's Advent Cantatas be reproduced correctly on Lowthers?
>>>
>>>What is your definition of "correctly"
>>>
>>>Guido
>>>
>>>>Thank you in advance,
>>>>
>>>>David Klein
>>>>
>>Well, it seems to me the composer wrote these cantatas to be played on
>>direct radiating loudspeaker systems such as the Advents, hence the title of
>>the works in question ...
>
>Ah ! But will we ever know whether it will be correctly translated via
>direct radiating loudspeakers ?
>
>Guido
>
>>David
>>
>>
>
What kind of monitors do you think Bach had in his own studio?
dbk
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: Better Lowther?
Date: Wed, 28 Oct 1998 19:08:59 +0100
Source: Sound Digest Archive v01.n472
At 07:09 28-10-98 -0500, David B. Klein wrote:
>At 09:42 PM 10/27/98 +0100, Bert Doppenberg wrote:
>>Hi all,
>>
>>What is this about a better Lowther? Better then wich type? Or totaly
>>different speakers?
>>
>>Anybody who is seeking for a better Lowther, did they already listened to
>>the PM5,
>>PM4 or DX4 units in a suitable enclosure??
>>
>>Or are we talking about the C-series which should be improved?
>>
>>Regards,
>>
>>Bert
>
>Can Bach's Advent Cantatas be reproduced correctly on Lowthers?
What is your definition of "correctly"
Guido
>Thank you in advance,
>
>David Klein
>
>
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: Better Lowther?
Date: Wed, 28 Oct 1998 19:22:35 +0100
Source: Sound Digest Archive v01.n472
>>>Can Bach's Advent Cantatas be reproduced correctly on Lowthers?
>>
>>What is your definition of "correctly"
>>
>>Guido
>>
>>>Thank you in advance,
>>>
>>>David Klein
>>>
>Well, it seems to me the composer wrote these cantatas to be played on
>direct radiating loudspeaker systems such as the Advents, hence the title of
>the works in question ...
Ah ! But will we ever know whether it will be correctly translated via
direct radiating loudspeakers ?
Guido
>David
>
>
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: Re: Better Lowther?
Date: Thu, 29 Oct 1998 13:50:04 +0100
Source: Sound Digest Archive v01.n472
- ----------
> De : David B. Klein <dklein@microtec.net>
> Date : jeudi 29 octobre 1998 13:31
> Bach went blind at the very end of his life; Beethoven is the one who
> was deaf. I imagine Bach having QUAD ELSs, with tubed electronics, of
> course.
David,
Oh silly me! I remember now, yes he was blind.
But how that blind guy succeed in marrying Barbara (Bach)!
(A bad joke!)
Best regards,
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: Better Lowther?
Date: Wed, 28 Oct 1998 20:09:21 GMT
Source: Sound Digest Archive v01.n473
On Wed, 28 Oct 1998 13:24:37 -0500 (EST), "David B. Klein"
<dklein@microtec.net> wrote:
>What kind of monitors do you think Bach had in his own studio?
I think she used Altecs. Oh, wait, that's Wendy Carlos, nee
Walter....
- --dnb
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: Better Lowther?
Date: Fri, 30 Oct 1998 18:35:02 +0100
Source: Sound Digest Archive v01.n473
At 13:24 28-10-98 -0500, David B. Klein wrote:
>At 07:22 PM 10/28/98 +0100, evaguido wrote:
>>>>>Can Bach's Advent Cantatas be reproduced correctly on Lowthers?
>>>>
>>>>What is your definition of "correctly"
>>>>
>>>>Guido
>>>>
>>>>>Thank you in advance,
>>>>>
>>>>>David Klein
>>>>>
>>>Well, it seems to me the composer wrote these cantatas to be played on
>>>direct radiating loudspeaker systems such as the Advents, hence the
title of
>>>the works in question ...
>>
>>Ah ! But will we ever know whether it will be correctly translated via
>>direct radiating loudspeakers ?
>>
>>Guido
>>
>>>David
>>>
>>>
>>
>What kind of monitors do you think Bach had in his own studio?
No idea ! Don't know the man, besides from his music
Guido
>dbk
>
>
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: RE: Better Lowther?
Date: Fri, 30 Oct 1998 17:16:02 -0500 (EST)
Source: Sound Digest Archive v01.n474
At 08:55 AM 10/31/98 +1100, Bart wrote:
>
>
>
>>What kind of monitors do you think Bach had in his own studio?
>>
>
>It is a well known and documented fact that Bach used Tuned Pipes.
>>
>
>
:-) :-) :-)
=========================================================================
From: darmah@goodnet.com
Subject: Better Lowther??? the problem is....
Date: Tue, 27 Oct 1998 22:20:00 -0700
Source: Sound Digest Archive v01.n471
Hi Joes:
Well seems my favorite subject has a thread running once again.
As of late I stay out of most Lowther discussions, since all I really
am is a "Lowther basher" gone business man ( huh Pat).
Gees... business ain't too swift these days.
But seeing how todays my Birthday and I'm happy from too much
beer and not happy about getting older and all I think I'll make a few
comments:
There exist at this time several Lowther knock offs all claiming to
be what the Lowther wants to be.
While I've heard one or two of them and can say I was quite
impressed the drivers in question are usually much more expensive
than even the expensive Lowther models.
One thing often overlooked when dealing with Lowthers is that more
money may buy you what appears to be a better driver, i.e.
stronger driver, this may NOT suit the application in question and
results can be worse than with a cheaper model.
Now I will say that I have seen people choose the PM 2 C and also
even the DX 2 over my favorite PM 2 A. I don't doubt for one second
that there was good reason to do so, but I think there were other
system and or enclosure related factors involved in the "subjective"
decision making process.
The variables associated with Lowther drivers are tremendous and
it is only the clear understanding of several key characteristics and
their interactions amoung the different drivers that will lead to the
successfull application of the chosen model.
Taste not withstanding.
The PM 4 A and The PM 5 A were brought up and are a good case
in point.
Donald Chave was no dummy folks. The PM 4 A was never
intended for direct radiating applications and using it anything but
an Audiovector is sure to lead to marginal if not poor results.
The PM 5 A has PM 2 A type magnetics and the permandure pole
center of the PM 4 A. It's still too powerfull a driver for 99 % of all
direct radiating applications and only fairs well in a large horns.
People who use this driver in smaller enclosures never stop
searching for ways to improve the low end.
Not that there are not ways to get the most out even these drivers
in direct raditing applications, but things like equalization and
"artificial" reactance annulling are things triode purists surely will
not want to consider. NOT meant in any way as a critisism.
One guy wrote me that he "accidentally" put PM 6 C's in the front
position of his Academy's in place of the PM 5 A's normally used.
"It sounds so much more balanced I can't go back. What do I do
with my expensive PM 5 A's"
I'm not surpised. I've been beating the tonal balance and what to do
about it drum for ages. See my web page.
The wrong driver in the wrong enclosure in the wrong system will
make people who don't know what can be had from Lowthers look
for a better Lowther.
I tried very hard to clear some of these issues up as best I could at
the time on my Lowther enthusiasts web page. If you heven't seen
it please have a look. URL in my signature.
Is there "better" Lowther? Well maybe but if the Lowther fails to
please I would say in 80 % of the time it's a matter of using the
Lowther incorrectly.
As Dieter says: "There has never been a Fostex, in spite of thier
physical beauty and excellent craftsmanship that can outplay a
<bold><underline>properly running and set up Lowther"</underline></bold>
People have asked me: "What do you think of the REPS 1. I heard
it and was very impressed"
I also heard Lowther and didn't like too much."
Some investigation then reveals that the auditions of the indevidual
systems were several weeks apart. The Lowther in question was a
white coned, C type PM 6 of unkown vintage in a small horn as
part of a system that the listener even described as not what he
would own.
Hardly a fair comparison.
Don't get me wrong here I'm not knpocking the REPs 1. But I think
comparisons need to be fair.
I had the privilege of seeing the Reps 1 being built as well hearing it
in one of Roberts Lam Horns. Although this was well over a year
ago when Frank and I still had contact.
Frank has done an incredible job of taking the Lowther design to
what HE (hint) thinks it should be. And it just may be the best full
range driver in the universe.
BUT!!!!!!!
I myself, while quite impressed with what I heard have NEVER
heard it in a direct and FAIR comparison with a Lowther.
No offense Robert but comparing the Reps 1 in your Lam Horn to
older white coned PM2 C's in Lowther Delphics is NOT a fair
comparison.
On a prior occasion Frank wouldn't let me bring down my PM 2 A's
for a direct comparison. That in my opinion would have been fair,
since the magnetics are somewhat similar. So long as the same
enclosure were used of course.
I'd still like to hear a really fair comparison of the REPs1 or any
other better Lowther against what I have or what I know to be a
good Lowther.
Man I really hope the REPs 1 would kick my PM 2 A's ass all over
the Arizona desert. If the ass kicking were good enough I'd sell my
Darmah and buy a pair of Reps ones myself.!!!
But replacing the PM 5 A with a REPs 1 doesn't impress me.
My guess is there are other Lowther drivers that would have faired
better than the PM 5 in the systems in question.
Those that may have not yet, view my page. I'm not sure if it will be
up too much longer.
Best Regards
<nofill>
Marc S. Wauters
darmah@goodnet.com
My Lowther Enthusiasts Page:
"http://www.goodnet.com/~darmah/lowther/lowther.htm"
=========================================================================
From: Robert Lamarre <rlamarre@rlacoustique.com>
Subject: Re: Better Lowther??? the problem is....
Date: Wed, 28 Oct 1998 10:01:27 -0500
Source: Sound Digest Archive v01.n471
At 10:20 PM 10/27/98 -0700, you wrote:
>Hi Joes:
>
>Well seems my favorite subject has a thread running once again.
>
>As of late I stay out of most Lowther discussions, since all I really am
is a "Lowther basher" gone business man ( huh Pat).
>
>Gees... business ain't too swift these days.
>
>But seeing how todays my Birthday and I'm happy from too much beer and not
happy about getting older and all I think I'll make a few comments:
>
>There exist at this time several Lowther knock offs all claiming to be
what the Lowther wants to be.
>While I've heard one or two of them and can say I was quite impressed the
drivers in question are usually much more expensive than even the expensive
Lowther models.
>
>One thing often overlooked when dealing with Lowthers is that more money
may buy you what appears to be a better driver, i.e. stronger driver, this
may NOT suit the application in question and results can be worse than with
a cheaper model.
>
>Now I will say that I have seen people choose the PM 2 C and also even the
DX 2 over my favorite PM 2 A. I don't doubt for one second that there was
good reason to do so, but I think there were other system and or enclosure
related factors involved in the "subjective" decision making process.
>
>The variables associated with Lowther drivers are tremendous and it is
only the clear understanding of several key characteristics and their
interactions amoung the different drivers that will lead to the successfull
application of the chosen model.
>Taste not withstanding.
>
>The PM 4 A and The PM 5 A were brought up and are a good case in point.
>Donald Chave was no dummy folks. The PM 4 A was never intended for direct
radiating applications and using it anything but an Audiovector is sure to
lead to marginal if not poor results.
>
>The PM 5 A has PM 2 A type magnetics and the permandure pole center of the
PM 4 A. It's still too powerfull a driver for 99 % of all direct radiating
applications and only fairs well in a large horns.
>People who use this driver in smaller enclosures never stop searching for
ways to improve the low end.
>
>Not that there are not ways to get the most out even these drivers in
direct raditing applications, but things like equalization and "artificial"
reactance annulling are things triode purists surely will not want to
consider. NOT meant in any way as a critisism.
>
>One guy wrote me that he "accidentally" put PM 6 C's in the front position
of his Academy's in place of the PM 5 A's normally used.
>
>"It sounds so much more balanced I can't go back. What do I do with my
expensive PM 5 A's"
>
>I'm not surpised. I've been beating the tonal balance and what to do about
it drum for ages. See my web page.
>
>The wrong driver in the wrong enclosure in the wrong system will make
people who don't know what can be had from Lowthers look for a better Lowther.
>
>I tried very hard to clear some of these issues up as best I could at the
time on my Lowther enthusiasts web page. If you heven't seen it please have
a look. URL in my signature.
>
>Is there "better" Lowther? Well maybe but if the Lowther fails to please I
would say in 80 % of the time it's a matter of using the Lowther incorrectly.
>As Dieter says: "There has never been a Fostex, in spite of thier physical
beauty and excellent craftsmanship that can outplay a properly running and
set up Lowther"
>
>People have asked me: "What do you think of the REPS 1. I heard it and was
very impressed"
>I also heard Lowther and didn't like too much."
>
>Some investigation then reveals that the auditions of the indevidual
systems were several weeks apart. The Lowther in question was a white
coned, C type PM 6 of unkown vintage in a small horn as part of a system
that the listener even described as not what he would own.
>Hardly a fair comparison.
>
>Don't get me wrong here I'm not knpocking the REPs 1. But I think
comparisons need to be fair.
>
>I had the privilege of seeing the Reps 1 being built as well hearing it in
one of Roberts Lam Horns. Although this was well over a year ago when Frank
and I still had contact.
>
>Frank has done an incredible job of taking the Lowther design to what HE
(hint) thinks it should be. And it just may be the best full range driver
in the universe.
>BUT!!!!!!!
>I myself, while quite impressed with what I heard have NEVER heard it in a
direct and FAIR comparison with a Lowther.
>
>No offense Robert but comparing the Reps 1 in your Lam Horn to older white
coned PM2 C's in Lowther Delphics is NOT a fair comparison.
>
>On a prior occasion Frank wouldn't let me bring down my PM 2 A's for a
direct comparison. That in my opinion would have been fair, since the
magnetics are somewhat similar. So long as the same enclosure were used of
course.
>
>I'd still like to hear a really fair comparison of the REPs1 or any other
better Lowther against what I have or what I know to be a good Lowther.
>
>Man I really hope the REPs 1 would kick my PM 2 A's ass all over the
Arizona desert. If the ass kicking were good enough I'd sell my Darmah and
buy a pair of Reps ones myself.!!!
>
>But replacing the PM 5 A with a REPs 1 doesn't impress me.
>My guess is there are other Lowther drivers that would have faired better
than the PM 5 in the systems in question.
>
>Those that may have not yet, view my page. I'm not sure if it will be up
too much longer.
>
>Best Regards
>
>
>Marc S. Wauters
>darmah@goodnet.com
>
>My Lowther Enthusiasts Page:
>"http://www.goodnet.com/~darmah/lowther/lowther.htm"
>
>
Hi Marc,
Very good post, I agree with you in all areas.
The music is dependant on the enclosure as much as the driver.
When will people get this in their heads?
I will be in Vegas for the show this winter. Maybe we can set-up a fair
comparison then?
Not at the show but a couple of days before.
In any event keep in touch,
========== Robert Lamarre ===========
RL Acoustique, Creator of The Lamhorn
rlamarre@rlacoustique.com------------
www.rlacoustique.com-----------------
ph./fax: 450-653-3461 Canada---------
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@roads.sa.gov.au>
Subject: RE: Better Lowther??? the problem is....
Date: Fri, 30 Oct 1998 22:28:40 +1030
Source: Sound Digest Archive v01.n473
- -----Original Message-----
From: darmah@goodnet.com [mailto:darmah@goodnet.com]
>Man I really hope the REPs 1 would kick my PM 2 A's ass all over the
Arizona desert. If the ass >kicking were good enough I'd sell my Darmah
and buy a pair of Reps ones myself.!!!
You'd SELL your DARMAH???!!!!
=========================================================================
From: Ishmael349@aol.com
Subject: Re: Beware the brown mist!
Date: Fri, 15 Jan 1999 10:25:14 EST
Source: Sound Digest Archive v01.n577
Personaly, I think the number one public health problem is FARTING! Second
hand smoke and bad tobacco smells? How about airborne SHIT PARTICLES and
poison gas?
You can probably get HIV positive from eating and breathing wet shit and
rotting corn particles. Right? Not to mention it is my constitutional right
to eat in a environment free of noxious, smelly gas and free-floating shit.
The worse thing about public farting is the demographics. Unlike smoking
where the rich, educated, privilaged class smokes less (because they are
smarter as one of my fellow netters suggested) -- Farting knows nothing of
pecunary emulation. Actually, the fat and indolent appear to fart MORE in
public places.
The reason that farting has not been banned is purely a class issue. Unlike
smoking, where the percapita incidence of smoking increases as ones social
privilege and economic means decreases, (Smoking is a great issue because
gives the haves another stick to beat the have-nots with and keep them in
their place), farting is pan-social. "Noooo, Starvin Marvin thats' MY
four-star restaurant...YOU eat at Subway!" The pink-faced, porkers in their
Mercedes would never want to embarass themselves getting caught crapping their
shorts in at Chez Bonnet or the Union Cafe. Think about it. Why should I
have to endure the smell of liquid duky while I stand in line at the Buffet?
Let me here and now declare my god-given right to not be forced to smell other
people's airborne diarrhea! Consider the health of your loved ones - keep
your sphincter tight and:
"Beware the brown mist!!
HR
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: Beware the brown mist!
Date: Fri, 15 Jan 1999 16:16:35 -0500
Source: Sound Digest Archive v01.n578
Ishmael349@aol.com wrote:
>
> Personaly, I think the number one public health problem is FARTING! Second
> hand smoke and bad tobacco smells? How about airborne SHIT PARTICLES and
> poison gas?
>
> You can probably get HIV positive from eating and breathing wet shit and
> rotting corn particles. Right? Not to mention it is my constitutional right
> to eat in a environment free of noxious, smelly gas and free-floating shit.
> The worse thing about public farting is the demographics. Unlike smoking
> where the rich, educated, privilaged class smokes less (because they are
> smarter as one of my fellow netters suggested) -- Farting knows nothing of
> pecunary emulation. Actually, the fat and indolent appear to fart MORE in
> public places.
>
> The reason that farting has not been banned is purely a class issue. Unlike
> smoking, where the percapita incidence of smoking increases as ones social
> privilege and economic means decreases, (Smoking is a great issue because
> gives the haves another stick to beat the have-nots with and keep them in
> their place), farting is pan-social. "Noooo, Starvin Marvin thats' MY
> four-star restaurant...YOU eat at Subway!" The pink-faced, porkers in their
> Mercedes would never want to embarass themselves getting caught crapping their
> shorts in at Chez Bonnet or the Union Cafe. Think about it. Why should I
> have to endure the smell of liquid duky while I stand in line at the Buffet?
> Let me here and now declare my god-given right to not be forced to smell other
> people's airborne diarrhea! Consider the health of your loved ones - keep
> your sphincter tight and:
> "Beware the brown mist!!
>
> HR
Please ...
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: Beware the brown mist!
Date: Fri, 15 Jan 1999 19:30:51 GMT
Source: Sound Digest Archive v01.n578
On Fri, 15 Jan 1999 10:25:14 EST, Ishmael349@aol.com wrote:
> Consider the health of your loved ones - keep
>your sphincter tight and:
>"Beware the brown mist!!
Put a cork in it. <G>
- --dnb
=========================================================================
From: "PEARL Cust Serv" <custserv@pearl-hifi.com>
Subject: Re: Beware the brown mist!
Date: Fri, 15 Jan 1999 17:17:19 -0700
Source: Sound Digest Archive v01.n579
>David B. Klein" <dklein@microtec.net> wrote
>Ishmael349@aol.com wrote:
>>
>> Personaly, I think the number one public health problem is FARTING! Second
>> hand smoke and bad tobacco smells? How about airborne SHIT PARTICLES and
>> poison gas?
>>
>> You can probably get HIV positive from eating and breathing wet shit and
>> rotting corn particles. Right? Not to mention it is my constitutional right
>> to eat in a environment free of noxious, smelly gas and free-floating shit.
>> The worse thing about public farting is the demographics. Unlike smoking
>> where the rich, educated, privilaged class smokes less (because they are
>> smarter as one of my fellow netters suggested) -- Farting knows nothing of
>> pecunary emulation. Actually, the fat and indolent appear to fart MORE in
>> public places.
>>
>> The reason that farting has not been banned is purely a class issue. Unlike
>> smoking, where the percapita incidence of smoking increases as ones social
>> privilege and economic means decreases, (Smoking is a great issue because
>> gives the haves another stick to beat the have-nots with and keep them in
>> their place), farting is pan-social. "Noooo, Starvin Marvin thats' MY
>> four-star restaurant...YOU eat at Subway!" The pink-faced, porkers in their
>> Mercedes would never want to embarass themselves getting caught crapping their
>> shorts in at Chez Bonnet or the Union Cafe. Think about it. Why should I
>> have to endure the smell of liquid duky while I stand in line at the Buffet?
>> Let me here and now declare my god-given right to not be forced to smell other
>> people's airborne diarrhea! Consider the health of your loved ones - keep
>> your sphincter tight and:
>> "Beware the brown mist!!
>>
>> HR
>
>Please ...
========================
There's a very agreeable chat room in which I've spent some time over
the last year. On those very rare occasions when conversation would get to
heading in a direction that was seriously unacceptable, one had the option
of highlighting the name of the originator and selecting an option labelled
"Ignore User".
Would that such an option existed here....
BP
=========================================================================
From: Zyxtan@aol.com
Subject: Re: Beware the brown mist!
Date: Fri, 15 Jan 1999 21:16:20 EST
Source: Sound Digest Archive v01.n579
In a message dated 1/15/99 2:39:13 PM US Eastern Standard Time,
davidbarnett@aristotle.net writes:
> Put a cork in it. <G>
>
> --dnb
>
I second that, the post was repulsive,worthy of a large cork.
paul
=========================================================================
From: "Henry Platt" <hnplatt@massed.net>
Subject: Re: Beware the brown mist!
Date: Sat, 16 Jan 1999 14:31:34 -0500
Source: Sound Digest Archive v01.n580
>Ishmael349@aol.com wrote:
>>
>> Personaly, I think the number one public health problem is FARTING!
Second
>> hand smoke and bad tobacco smells? How about airborne SHIT PARTICLES and
>> poison gas?
>>
>> You can probably get HIV positive from eating and breathing wet shit and
>> rotting corn particles. Right? Not to mention it is my constitutional
right
>> to eat in a environment free of noxious, smelly gas and free-floating
shit.
>> The worse thing about public farting is the demographics. Unlike smoking
>> where the rich, educated, privilaged class smokes less (because they are
>> smarter as one of my fellow netters suggested) -- Farting knows nothing
of
>> pecunary emulation. Actually, the fat and indolent appear to fart MORE
in
>> public places.
>>
>> The reason that farting has not been banned is purely a class issue.
Unlike
>> smoking, where the percapita incidence of smoking increases as ones
social
>> privilege and economic means decreases, (Smoking is a great issue because
>> gives the haves another stick to beat the have-nots with and keep them in
>> their place), farting is pan-social. "Noooo, Starvin Marvin thats' MY
>> four-star restaurant...YOU eat at Subway!" The pink-faced, porkers in
their
>> Mercedes would never want to embarass themselves getting caught crapping
their
>> shorts in at Chez Bonnet or the Union Cafe. Think about it. Why should
I
>> have to endure the smell of liquid duky while I stand in line at the
Buffet?
>> Let me here and now declare my god-given right to not be forced to smell
other
>> people's airborne diarrhea! Consider the health of your loved ones -
keep
>> your sphincter tight and:
>> "Beware the brown mist!!
>>
>> HR
Beware the Fecal Eye.........
=========================================================================
From: Robert Jorgensen <robert.jorgensen@advalvas.be>
Subject: Re: Beware the brown mist!
Date: Sat, 16 Jan 1999 20:05:50 +0100
Source: Sound Digest Archive v01.n580
At 21:16 15/01/99 EST, you wrote:
>In a message dated 1/15/99 2:39:13 PM US Eastern Standard Time,
>davidbarnett@aristotle.net writes:
>
>> Put a cork in it. <G>
>>
>> --dnb
>>
>I second that, the post was repulsive,worthy of a large cork.
>
>paul
>
I wonder whether it's the new york artistic atmosphere that seems to drive
Herb or just a need to troll the list. Or perhaps it's just too much
flesh and blood.
Robert
=========================================================================
From: Dale.Simon@ps.net
Subject: biamped OPTs
Date: Thu, 18 Dec 1997 12:15:00 -0600
Source: Sound Digest Archive v01.n137
Hi all,
If a person were to biamp, how critical would the selection of
the OPT for the upper frequencies be? i.e. would the results be
satisfactory if the tranny rolled off at the bottom? and the
bottom frequencies were provided by a seperate amp.
Thanks,
Dale
=========================================================================
From: Dave Stagner <dstagner@icarus.net>
Subject: Bi-amping and power
Date: Thu, 13 Aug 1998 08:41:22 -0500 (CDT)
Source: Sound Digest Archive v01.n387
Just a followup on the bi-amping discussion, since i deleted the last post
on it before thinking of this...
Power is not evenly distributed across the frequency spectrum of music.
It is concentrated in the bass frequencies in a mathematical distribution.
Power distribution in sound falls into two classes - white and pink noise.
White noise distributes power equally across frequencies, and sounds
unpleasant (hiss). Pink noise weighs power to frequency, with more power
in the bass, and sounds pleasant (waterfall). Music, analyzed
statistically in terms of frequency and power, is pink noise.
Actually, "power" is misleading. Think of music in terms of stored energy
(measured in joules, not watts). It's too early in the morning for me to
remember the math, but energy is a function of power and *frequency* (just
as power is a function of force and resistance). As the frequency
increases, the amount of power required for a given energy decreases.
This is a cube relationship - the power required for a given energy level
is k/f^3, where f is the frequency.
Think about it... why are woofers huge surfaces with several mm of travel,
while tweeters are flimsy things with no visible movement? Which do you
think takes more power to move to full output?
To put this in practical terms, jc morrison once observed that 60% or so
of musical power occurs below 150hz. For bi-amping, this means a powerful
amp with large current reserves is needed for solid, well-controlled bass,
but considerably less power is required for the mids and treble.
Moreover, the ear is much more sensitive to distortion in the higher
frequencies (due to the higher energy), so more refined-sounding
amplifiers are appropriate.
It's a compelling argument. I plan on bi-amping my own system in the next
few months, with a 2A3 SE amp for the towers and a push-pull amp for the
subs.
- -dave
Practice beautiful randomness and act kind of senseless.
<dstagner@icarus.net>
=========================================================================
From: An-shyang Chu <achu@sandia.gov>
Subject: Re: Bi-amping and power
Date: 13 Aug 1998 09:00:35 -0600
Source: Sound Digest Archive v01.n387
Dave!!
Great post! I love the part about the noises. So.. 60% are below 150 Hz??? 60%
will be ~ the 1/e point of the power spectrum. This is very interesting. Maybe
this is why many have chosen the crossover f between mid and low drivers be
around 100 Hz (would be closer to the 1/e point than 150 Hz)?
hopper
_______________________________________________________________________________
<snip>.....
Power is not evenly distributed across the frequency spectrum of music.
It is concentrated in the bass frequencies in a mathematical distribution.
Power distribution in sound falls into two classes - white and pink noise.
White noise distributes power equally across frequencies, and sounds
unpleasant (hiss). Pink noise weighs power to frequency, with more power
in the bass, and sounds pleasant (waterfall). Music, analyzed
statistically in terms of frequency and power, is pink noise.
Actually, "power" is misleading. Think of music in terms of stored energy
<snip> ......
To put this in practical terms, jc morrison once observed that 60% or so
of musical power occurs below 150hz. For bi-amping, this means a powerful
amp with large current reserves is needed for solid, well-controlled bass,
but considerably less power is required for the mids and treble.
Moreover, the ear is much more sensitive to distortion in the higher
frequencies (due to the higher energy), so more refined-sounding
amplifiers are appropriate.
It's a compelling argument. I plan on bi-amping my own system in the next
few months, with a 2A3 SE amp for the towers and a push-pull amp for the
subs.
- -dave
Practice beautiful randomness and act kind of senseless.
<dstagner@icarus.net>
=========================================================================
From: Dave Stagner <dstagner@icarus.net>
Subject: Re: Bi-amping and power
Date: Thu, 13 Aug 1998 13:20:35 -0500 (CDT)
Source: Sound Digest Archive v01.n387
On 13 Aug 1998, An-shyang Chu wrote:
> Great post! I love the part about the noises. So.. 60% are below 150 Hz??? 60%
> will be ~ the 1/e point of the power spectrum. This is very interesting. Maybe
> this is why many have chosen the crossover f between mid and low drivers be
> around 100 Hz (would be closer to the 1/e point than 150 Hz)?
I doubt that speaker designers make decisions about crossover points based
on power distribution. Heck, you have to go out of your way to find a
speaker designer who isn't pretending that audio amplifiers are perfect
voltage sources with zero output impedance and no frequency-dependent
speaker interactions!
There are several practical reasons for crossing over around 150hz,
though. First, there is the popularity of bandpass subwoofers. It'd be
difficult to find a woofer with any significant bass that will bandpass
much above 150hz (interesting side note... the two bandpass types that
immediately spring to mind are the horrible little plastic shoeboxes we
see everywhere, and the Whamo subs. You could drop a pair of Bose sub-sat
systems in one chamber of a Whamo sub with room to spare. Then again, the
Whamo subs sound great, while the Bose...)
Another problem is that most woofers designed for low bass have tremendous
distortion and sound like crap at frequencies where our ears become most
sensitive. And finally, bass below 150hz or so becomes non-directional,
so in theory we can move the woofers around without affecting the stereo
image (this isn't quite so true in practice).
Think about the tube audio faves, Lowthers and Altec VOTs. Neither has
any usable output in the lowest octave, and both roll off severely in the
40-80hz octave. They sound good on a watt or two in part because they
just don't dip into the range where real power is needed.
This has interesting implications. The conventional wisdom is that
efficiency and a smooth impedance curve make speakers tube-compatible.
But good results have been reported using flea-powered 2A3 SE amps with
inefficient, weird-impedance speakers like Quad ESLs or Radio Shack LX-5s,
while efficient speakers with flat impedance like WATTs and Grand Slamms
don't work well with tube amps, even high-powered ones. Could this be
that the high power needs of the deep bass these speakers produce
overworks the amplifier? And there's the issue of impedance... while
these speakers may have flat impedances, they also have complex signal
paths, where the flat impedance is the net sum of many paralleled reactive
components. A Quad may have difficult impedance, but there's only one
source for its reactive nature. Meanwhile, we have Joenetters who are
perfectly happy listening to 90db single-driver Diatones with 3/4 watt
Spud amps...
Heck, this even sort of ties in to the ongoing debate about cathode
followers. While they may have low impedance on paper, they sound "tired"
when driving low-impedance loads, whether or not the match looks good on
paper. What i'm suggesting is that complex crossovers with impedance
correction may give a flat impedance on paper, but are still a strain for
tube amps with high output impedance. The flat impedance is really just a
sum of parallel highly reactive components, and each reactive component
causes the same sort of problems that it would if it was standing alone.
We can extend this whole idea to the drivers themselves. Speaker drivers
represent a terrible impedance mismatch. They are trying to drive