Sound Practices Mailing List Files - Volume 1
=========================================================================
From: Steve Van Osdell <svanos@toast.net>
Subject: Rabco Linear Turntable
Date: Sat, 25 Oct 1997 21:25:00 -0400
Source: Sound Digest Archive v01.n087
Does anyone here know anything about a Rabco Linear Track turntable model
SL4? I think it was made by Harmon Kardon.
Is it any good?
Thanks, Steve
=========================================================================
From: av599@lafn.org
Subject: Re: Rabco Linear Turntable
Date: Sun, 26 Oct 1997 07:25:31 -0800 (PST)
Source: Sound Digest Archive v01.n087
>Does anyone here know anything about a Rabco Linear Track turntable model
>SL4? I think it was made by Harmon Kardon.
>Is it any good?
>
>Thanks, Steve
Steve,
Rabco made two models themselves, the ST-4, which was IMHO a very nice
belt-driven, clock-motor (like the AR) turntable-arm combination, and the
SL-8E which was a servo-driven, battery-powered arm that generally was
attached to a Thorens TT. I have been using my ST-4 for about 25 years and
have not found anything I like well enough to replace it. H-K produced the
ST-7 turnrtable which was a disaster. They took the elegant simplicity of
the ST-4 and added all sorts of sliding tubes that made the arm have too
much friction. Kinda like the Forsell (sp?) air bearing without the air.
I'd leave the ST-7 alone.
Hope this helps
Doug
=========================================================================
From: Kalman Rubinson <rubinsnk@is2.nyu.edu>
Subject: Re: Rabco Linear Turntable
Date: Sun, 26 Oct 1997 18:08:19 -0500 (EST)
Source: Sound Digest Archive v01.n089
On Sun, 26 Oct 1997 av599@lafn.org wrote:
> Rabco made two models themselves, the ST-4, which was IMHO a very nice
> belt-driven, clock-motor (like the AR) turntable-arm combination, and the
> SL-8E which was a servo-driven, battery-powered arm that generally was
> attached to a Thorens TT. I have been using my ST-4 for about 25 years and
> have not found anything I like well enough to replace it. H-K produced the
> ST-7 turnrtable which was a disaster. They took the elegant simplicity of
> the ST-4 and added all sorts of sliding tubes that made the arm have too
> much friction. Kinda like the Forsell (sp?) air bearing without the air.
> I'd leave the ST-7 alone.
I beg to differ. I bought an old ST-7 about 2 years ago and the arm
was(!) a disaster. I little rebuild with HomeDepot parts resulted in a
superb tracker that sound quite good.
The sliding tubes are irrelevant since they are driven by the motor belt
and not directly involved in horizontal or vertical tracking. Besides, a
bit of cleaning keeps them running smoothly.
In general, I'd keep this one (so far, I have) over the SL-8 for use if
not for the museum. Haven't tried the ST4.
(BTW, the ST-7 used the same DC motor as did SOTA!)
Kal
=========================================================================
From: "Riesz, Ted - R&E" <Ted.Riesz@mailhost.dpie.gov.au>
Subject: Radford amp mods
Date: Tue, 28 Apr 1998 20:39:10 +1100
Source: Sound Digest Archive v01.n263
Hello
I picked one of these babies up at a local flea market.
EL 34 ultra linear PP with EF 86 and 6U8 pentode- triode splitter.
Wondering it it would be a good idea to convert to an all triode front end and triode connect the EL
34's.
Any thoughts
TIA
Ted Riesz
=========================================================================
From: "Mark Donen" <soledadd@worldnet.att.net>
Subject: Re: Radford amp mods
Date: Fri, 1 May 1998 08:12:28 -0400
Source: Sound Digest Archive v01.n265
I will keep my STA15 essentially as original. Just upgrade the power
suppy caps and go back to a GZ34 (my sample has been converted to ss
diodes). Suspect this design which relies on high gain pentode gain and
high levels of NF would not lend itself to conversion to lower gain triode
and less NF.
Hi Ted,
The Radford has a bit of value in the UK and other markets where they were
originally distributed -- I remember back in the good old 70s when LP12s
and Naim amps dominated hifi ideology, that some guy wrote in to a mag
saying "my Radford sounds better than my Naim -- I can't understand it."
Suddenly everyone was buying the exact same Radford model he had. They
thought there was something magical about that particular model -- hence
the reason why its originality is valued.
To my way of thinking, the only reason to keep it original is monetary
value. Sonically, it just isn't that interesting. From an unteary eyed pov,
it is just a chassis, a set of sockets, power tranny and opts from which
you can make decent a zero nf trioded class a pp amp, if you do it from
scratch. Pitch the circuit and all the passive components and wiring. When
you are done, it might be worth more to you as an amplifier. However, if
you are just looking old amps as a convient and cheap source of parts, you
might do better to look at some of the theater amps -- they seem to have
very little sentimental value. Dynas have been modded in a large variety of
ways too, as you say, because they don not have a lot of value.
Mark
=========================================================================
From: "Riesz, Ted - R&E" <Ted.Riesz@mailhost.dpie.gov.au>
Subject: Radford amp mods
Date: Fri, 1 May 1998 20:07:52 +1100
Source: Sound Digest Archive v01.n265
Hello
I wish to ally the concerns of a number of Joes who feel that a Radford should not be substantially
modded.
I will keep my STA15 essentially as original. Just upgrade the power suppy caps and go back to a GZ
34 (my sample has been converted to ss diodes). Suspect this design which relies on high gain pento
de gain and high levels of NF would not lend itself to conversion to lower gain triode and less NF.
However not being a sentimentalist, I am curious about the preservation value of these sorts of amp
s. I note people seem happy to mod dynas etc but not some of the classic UK amps. Is this because
there are many more dynas? . I must admit the Radford looks cool, if I may use that expression,.as
do the QUAD II's and the QUAD 22.
I will depart now for my trip to the US and Europe having raised this point.
Hope to fire up the Radford when I get back and will then report on my impression of its sound
Be back in 3 weeks.
Regards
Ted
=========================================================================
From: Grego Sanguinetti <grego@lscpdx.latticesemi.com>
Subject: radial engine amp, was: Re: what i did this weekend 8/2
Date: Wed, 5 Aug 1998 11:25:25 -0700
Source: Sound Digest Archive v01.n377
On Wed, Aug 05, 1998 at 09:52:51AM -0400, Danielak, Robert M wrote:
> been in a real grumpy mood, lately. ;(
sorry to hear about that, hope it works out...
> anyway,
>
> that radial-engine motif sounds COOL!
> for some reason i picture it with those big russian triodes 6C33, etc...
they would be ok, but the mikey mouse tubes look more like the
traditional radial engine cylinders. Also, I have a box full of
815's. The other problem is the huge filament power for the 6C33's.
By the way, in triode mode the 815's are more linear. The shiny
metal bases of the 815s are another big plus, for this look.
> i even laid out a chassis on my CAD system.
> i set the tubes and other components in the form of the
> constellation "pleiades"
>
> a co-worker remarked "looks like a subaru commercial..."
B^)
> i have been thinking of different ways of turning this audio art into
> a form of visual art...
>
> your ideas has the added appeal to the gear-head in all of us!
Or the propellor head!
One issue that sort of hung me up with this radial engine idea
was the core chassis. It needs to be round and three dimentional
to give it that engine core look. I had thought about a small
aluminum brake drum (Carter?) but then the issue is what to
do about the steel lining?
Pretty silly really, but it would look pretty cool. Make
a good conversation piece for my new office/shop!
- -grego
=========================================================================
From: Joe Pledger <doodle@navicom.com>
Subject: Re: radial engine amp, was: Re: what i did this weekend 8/2
Date: Wed, 05 Aug 1998 14:22:44 -0700
Source: Sound Digest Archive v01.n377
Grego Sanguinetti wrote:
>
> On Wed, Aug 05, 1998 at 09:52:51AM -0400, Danielak, Robert M wrote:
> > been in a real grumpy mood, lately. ;(
>
> sorry to hear about that, hope it works out...
>
> > anyway,
> >
> > that radial-engine motif sounds COOL!
> > for some reason i picture it with those big russian triodes 6C33, etc...
>
> they would be ok, but the mikey mouse tubes look more like the
> traditional radial engine cylinders. Also, I have a box full of
> 815's. The other problem is the huge filament power for the 6C33's.
> By the way, in triode mode the 815's are more linear. The shiny
> metal bases of the 815s are another big plus, for this look.
>
> > i even laid out a chassis on my CAD system.
> > i set the tubes and other components in the form of the
> > constellation "pleiades"
> >
> > a co-worker remarked "looks like a subaru commercial..."
>
> B^)
>
> > i have been thinking of different ways of turning this audio art into
> > a form of visual art...
> >
> > your ideas has the added appeal to the gear-head in all of us!
>
> Or the propellor head!
>
> One issue that sort of hung me up with this radial engine idea
> was the core chassis. It needs to be round and three dimentional
> to give it that engine core look. I had thought about a small
> aluminum brake drum (Carter?) but then the issue is what to
> do about the steel lining?
>
> Pretty silly really, but it would look pretty cool. Make
> a good conversation piece for my new office/shop!
>
> -grego
Hi grego,
As one with just a pile of parts on a bench, I shouldn't comment...but,
you might get some inspiration at one of those places that buy scrap
metal. The last time the wife needed a ride to Smith & Hawken, I
wandered next door to an Art? gallery. Someone had constructed a hugh
duck out of stainless steel scrap. An amazing example of adaptive trash!
but it was great. How about an old polished Edelbrock intake manifold?
If it was set up for dual carbs, you'd have room for 8 tubes.
Joe Pledger
=========================================================================
From: Grego Sanguinetti <grego@lscpdx.latticesemi.com>
Subject: Re: radial engine amp, was: Re: what i did this weekend 8/2
Date: Wed, 5 Aug 1998 15:33:15 -0700
Source: Sound Digest Archive v01.n378
Yes, well, I have gotten a lot of replies on the radial engine
look idea. You have provided me with a bunch of energy to
explore it, but as I said, it will have to wait a bit.
But at least I don't need electricity in the shop to scrounge
for parts. Hey Joe, got any recommendations for metal yards?
The ones I use only sell bulk aluminum and I don't remember
seeing anything that would work, short of a 25 foot long
section of huge extruded tubing! They would cut it for me
but I would have to buy the whole length, ouch.
Hey, this would be a good project for those round potted
toroidal transformers!
What I really need is a local machinist with a huge
metal lathe that loves beer B^) Or maybe I should go
looking in a Pratt & Whitney dumpster B^)
and one hell of a strong hook on the wall. Maybe I will
frame that in as we are building the shop B^)
plus I will have to build an engine stand to work on
the sucker...
Frank,
I think alot of manufacturers are in fact fully focussed
on the pure visual appeal of the tube gear, such as Wavac,
Bel-Canto, Wavestream,... In fact the (I think ugly
but interesting) Wavestream V8 amp is what originally
got me thinking about the radial amp.
- -grego (shaking his head and....)
=========================================================================
From: Grego Sanguinetti <grego@lscpdx.latticesemi.com>
Subject: Re: radial engine amp, was: Re: what i did this weekend 8/2
Date: Wed, 5 Aug 1998 15:51:31 -0700
Source: Sound Digest Archive v01.n378
On Wed, Aug 05, 1998 at 02:22:44PM -0700, Joe Pledger wrote:
> .... How about an old polished Edelbrock intake manifold?
> If it was set up for dual carbs, you'd have room for 8 tubes.
Hey there you go! One of you nut cases that are building
PP845 amps. Get a Weber manifold for vertical 40mm's and
build in the UX4 sockets into the carb seats. Way cool!
- -grego (trying to avoid doing the reports today...)
=========================================================================
From: Joe Pledger <doodle@navicom.com>
Subject: Re: radial engine amp, was: Re: what i did this weekend 8/2
Date: Wed, 05 Aug 1998 18:09:15 -0700
Source: Sound Digest Archive v01.n378
Grego Sanguinetti wrote:
>
> Yes, well, I have gotten a lot of replies on the radial engine
> look idea. You have provided me with a bunch of energy to
> explore it, but as I said, it will have to wait a bit.
>
> But at least I don't need electricity in the shop to scrounge
> for parts. Hey Joe, got any recommendations for metal yards?
-snip-
I'd check for the name on the scrap metal dumpsters you see out back
of the Tek company store. I don't have any personal experience
with any particular scrap yard except one in Salem. I could maybe get
you an old Lycoming aircraft engine...but he'd probably want a lot for
it??!! He does have a lot of weird scrap there.
> What I really need is a local machinist with a huge
> metal lathe that loves beer B^) Or maybe I should go
> looking in a Pratt & Whitney dumpster B^)
- Reminds me of that GP driver who had a Formula I car
hanging on his livingroom wall.
Regards,
Joe Pledger
> and one hell of a strong hook on the wall. Maybe I will
> frame that in as we are building the shop B^)
> plus I will have to build an engine stand to work on
> the sucker...
>
> Frank,
>
> I think alot of manufacturers are in fact fully focussed
> on the pure visual appeal of the tube gear, such as Wavac,
> Bel-Canto, Wavestream,... In fact the (I think ugly
> but interesting) Wavestream V8 amp is what originally
> got me thinking about the radial amp.
>
> -grego (shaking his head and....)
=========================================================================
From: Richard C Nevill <rnevill@is.dal.ca>
Subject: Re: radial engine amp, was: Re: what i did this weekend 8/2
Date: Thu, 6 Aug 1998 11:56:58 -0300 (ADT)
Source: Sound Digest Archive v01.n378
On Wed, 5 Aug 1998, Joe Pledger wrote:
>
> - Reminds me of that GP driver who had a Formula I car
> hanging on his livingroom wall.
>
Race cars hanging on walls is pretty standard practice in the shops of
most proffesional teams. And a bunch of those "car theme" cafe/resturant
sort of places always have cars on the walls (if I remember correctly
there is one near Detroit that has a top fueler, funny car, hydoplane,
sprint car. indy car and some others hangin' over your head while you
scarf your cheeseburger).
I've been trying for a couple of years to get the wife to let me put a '69
Charger RT on our wall. So far no go, however :-) Not alot of WAF I guess.
Cheers
Richard Nevill
> >
> > -grego (shaking his head and....)
>
=========================================================================
From: Jeremy Epstein <jepstein@shwd.com>
Subject: Radial Engine Idea
Date: Mon, 10 Aug 1998 08:50:32 -0400
Source: Sound Digest Archive v01.n382
While staring at my living room ceiling the other night I had an idea -
if you guys are serious about this radial tube engine thing.
Ceiling fans have fancy round slotted housings that might do the trick,
and I see them discarded in the trash often, sometimes made from solid
brass. There's usually even a 5uF cap inside free for the salvage!
- -j
- --
=====================================
Jeremy Epstein .... jepstein@shwd.com
=====================================
=========================================================================
From: Grego Sanguinetti <grego@latticesemi.com>
Subject: RadioCoin 6B4G, was Re: sound-digest V1 #177
Date: Mon, 2 Feb 1998 16:33:52 -0800 (PST)
Source: Sound Digest Archive v01.n180
On Sat, 31 Jan 1998 ned@triodeel.com wrote:
> At 09:38 PM 1/31/98 -0600, Jim DeKort wrote:
>
> >2x 6B4G RadioCoin (RCA) NOB 35.00
>
> RadioCoin was a company that sold coin operated
> radios for use in hotels & motels.
> Musta been a fancy hotel, if the radio had
> 6B4-G's in it! Class A triode in 1947, musta been the
> Waldorf Astoria!
Yeah, I picked up a bunch of those at a swap meet
last year. The ones I got are all the same and look
exactly like my KenRad 6B4G's. I also got two
RadioCoin boxed 45's so I guess they did make some
fancy radios.
- -grego
=========================================================================
From: Larry Van Wormer <lvw@bmts.com>
Subject: Radio Designer's Handbook
Date: Mon, 29 Dec 1997 12:52:18 -0500
Source: Sound Digest Archive v01.n146
I saw this mentioned on one of the newsgroups, as I remember, and
thought it might be of interest: The Radio Designer's Handbook, Edition
4, has been re-published. Barnes and Noble lists it for $66.95.
ISBN 0750636351
The publisher, Butterworth-Heinemann, says this is the 4th edition,
although they only list it as 1000 pages, vs about 1500 pages for the
original. I've taken a chance and ordered one, even so, since I haven't
had any luck turning up an original for a reasonable price.
I checked with Old Colony, as I'd prefer to support them, but they don't
stock it yet. They say they will sometime in the future.
Has anyone seen this book?
Larry Van Wormer
=========================================================================
From: Gab <gabitzkw@webwide.net>
Subject: Radio Designer's Handbook
Date: Wed, 07 Oct 1998 12:28:29 -0500
Source: Sound Digest Archive v01.n444
Guys - just received my copy in today's mail!
For those of you who don't yet own a copy, I got mine from:
Opamp Technical Books
Voice 1-800-468-4322 323-464-4322
Fax 323-464-0977 E-mail opamp@netcom.com
Kurt Gabitzsch
=========================================================================
From: Dale.Simon@ps.net
Subject: Re: Radio Designer's Handbook
Date: Thu, 8 Oct 1998 16:13:00 -0500
Source: Sound Digest Archive v01.n447
- ------ =_WT12671.361d1da6.0a0/dcuh029.dcu.ps.net
Content-Type: text/plain; name="Authorized by..."; charset=us-ascii
Content-Disposition: inline; filename="Authorized by..."
Message authorized by:
: gabitzkw@webwide.net%smtp at x400po
- ------ =_WT12671.361d1da6.0a0/dcuh029.dcu.ps.net
Hey thanks for the tip. Are these really new reprints?
Dale
______________________________ Reply Separator _________________________________
Subject: Radio Designer's Handbook
Author: owner-sound@lists.io.com%smtp at x400po
Date: 10/7/98 12:25 PM
Guys - just received my copy in today's mail!
For those of you who don't yet own a copy, I got mine from:
Opamp Technical Books
Voice 1-800-468-4322 323-464-4322
Fax 323-464-0977 E-mail opamp@netcom.com
Kurt Gabitzsch
- ------ =_WT12671.361d1da6.0a0/dcuh029.dcu.ps.net--
=========================================================================
From: Gab <gabitzkw@webwide.net>
Subject: Re: Radio Designer's Handbook
Date: Thu, 08 Oct 1998 19:58:56 -0500
Source: Sound Digest Archive v01.n447
Dale - yes these are the real thing - all 1498 pages. $66.95 cover reads : Radio Designers Handbook
Fourth edition 1953,
revised 1967 F Langford-Smith. Blue hardcover with gold lettering
Dale.Simon@ps.net wrote:
> Hey thanks for the tip. Are these really new reprints?
>
> Dale
=========================================================================
From: "blackie" <blackie@mail.infohouse.com>
Subject: Radio free Marshall
Date: Thu, 14 May 1998 15:50:40 +0000
Source: Sound Digest Archive v01.n281
Sorry, I replied to this post but my mail server has been "F"'d
lately...
The standard amp mechanic fix for RF in a Marshall is to shunt 100pf
between 1st gain stage plate and grid....
After checking tube and cable of course, but you knew that :)
Blackie
blackie@tubesville.com
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: Re: Radio List
Date: Fri, 03 Oct 1997 11:56:19 -0700
Source: Sound Digest Archive v01.n056
To all,
I think I might have screwed up somehow and lost a reply or two
regarding a request for the radio list. So if you have asked and didn't
receive, please ask, ask again. Also, an inquiry about the tape
recorder. Thanks.
Dan Marshall
=========================================================================
From: Mike Hathaway <triode@t-three.com>
Subject: Radio quality
Date: Fri, 21 Aug 1998 13:14:46 -0700
Source: Sound Digest Archive v01.n398
My dad is an old broadcast engineer, and its interesting to have watched
the evolution of the broadcast media. The most notable innovation is the
asynchronous limiters they've developed. The FCC monitors overmodulation
closely to avoid splattering over into adjacent channels. In response the
broadcast industry has developed numerous devices to stay within the letter
of the law, and since the FCC no longer has any real engineering talent,
nobody's in any danger of being cited. Compression is bad, but
asynchronous limiting is insideous.
Another interesting thing is the band-limiting that goes on. My dad has
spectrum analyzer data showing decent frequency response out to about 15
KHz from when he was Chief Engineer for Fisher Broadcasting, and AM in the
60's was pretty decent. Now they put a brick wall filter at 7500 Hz and
call it good enough for talk radio. Its amazing that such a small segment
of the population is even aware that it changed. We truly are on the
fringe here.
And if that wasn't enough, my new home has new "anti-scald" temperature
controls in the showers. I now have the choice of tepid through "Holy S--t
that's cold!", and I have to buy a $15.00 tool from Delta to adjust it! To
which I ask - are these things happening because we are becoming a race of
idiots, or are we becoming idiots because we aren't allowed to think for
ourselves anymore? Just a thought.
Mike Hathaway
Mad as hell, but nobody cares anymore...
=========================================================================
From: David Bardes <David_Bardes@zd.com>
Subject: Re: Radio quality
Date: Fri, 21 Aug 1998 14:42:59 -0700
Source: Sound Digest Archive v01.n398
Me thinks the CEO's who have become the victims of law suits have tried to
make things full proof (without success):
Objects in mirror are closer than they appear. Etc.
My personal favorite is the law suit by the woman whose improper use of
spermicidal jelly (she spread it on toast!!!) resulted in her unwanted
pregnancy. I can't wait for the warning label that results from this
litigation!!
Mike Hathaway wrote:
> To
> which I ask - are these things happening because we are becoming a race
of
> idiots, or are we becoming idiots because we aren't allowed to think for
> ourselves anymore? Just a thought.
I especially like the coffee cups at McDonald's.
David
=========================================================================
From: Mike Hathaway <triode@t-three.com>
Subject: Re: Radio quality
Date: Fri, 21 Aug 1998 14:52:13 -0700
Source: Sound Digest Archive v01.n398
At 04:55 PM 8/21/98 EDT, you wrote:
>In a message dated 8/21/98, 4:30:15 PM, triode@t-three.com writes:
><< Now they put a brick wall filter at 7500 Hz and >>
>
>Why?
>
><< call it good enough for talk radio. >>
Why waste effective radiated power on Rush Limbaugh?
Mike Hathaway
Don't ask me, I only work here...
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: Radio quality
Date: Fri, 21 Aug 1998 17:07:36 -0400
Source: Sound Digest Archive v01.n398
Mike Hathaway wrote:
> To
> which I ask - are these things happening because we are becoming a race of
> idiots, or are we becoming idiots because we aren't allowed to think for
> ourselves anymore? Just a thought.
I especially like the coffee cups at McDonald's.
JL
=========================================================================
From: Ron Bales <rbales@gte.net>
Subject: Re: Radio quality
Date: Fri, 21 Aug 1998 21:48:33 -0400
Source: Sound Digest Archive v01.n399
Mike Hathaway wrote:
>
>
> And if that wasn't enough, my new home has new "anti-scald" temperature
> controls in the showers. I now have the choice of tepid through "Holy S--t
> that's cold!", and I have to buy a $15.00 tool from Delta to adjust it! To
> which I ask - are these things happening because we are becoming a race of
> idiots, or are we becoming idiots because we aren't allowed to think for
> ourselves anymore? Just a thought.
I manage an apartment complex - one of my more interesting recent
adventures involved a child scalder who then tampered with the water heater
and then threatened to sue us. It almost doesn't pay to deal with the
public.
ROn
=========================================================================
From: Ron Bales <rbales@gte.net>
Subject: Re: Radio quality
Date: Fri, 21 Aug 1998 21:51:15 -0400
Source: Sound Digest Archive v01.n399
David Bardes wrote:
>
> Me thinks the CEO's who have become the victims of law suits have tried to
> make things full proof (without success):
>
> Objects in mirror are closer than they appear. Etc.
Harry Chapin. He'd just put stylish new mirrors on his Volkswagen and was
tooling down the Long Island Distressway and changed lanes into a truck....
ROn
=========================================================================
From: "Jon Lane" <jhlane@email.msn.com>
Subject: RE: Radiotron Designers Handbook
Date: Tue, 21 Jul 1998 20:22:18 -0700
Source: Sound Digest Archive v01.n352
> Gang - it appears that the 4th addition of the Radiotron Designers
> Handbook is being reprinted effective this month.
> Price: L35.00, US $66.95, AUS$125.00
Sorta blows a hole in all the guys trying to get $250US for their old
copies...paid ten bucks for mine. =o)
=========================================================================
From: Kurt Gabitzsch <gabitzkw@webwide.net>
Subject: Radiotron Designers Handbook
Date: Tue, 21 Jul 1998 21:12:36 -0500
Source: Sound Digest Archive v01.n352
Gang - it appears that the 4th addition of the Radiotron Designers
Handbook is being reprinted effective this month. The details as they
have been provided to me are:
ISBN: 0750636351
Title: Radio Designer's Handbook (I think this is a typo, leaving off
the "tron")
Org Code: MTHK
Main Author Surname: Langford-Smith
Publication Date: 30/07/1998
Country of Origin: United Kingdom
Pages: 1498
Edition: 4th
Line Illustrations: 920 line illustrations
Product Type: Paperback
Price: L35.00, US $66.95, AUS$125.00
There is then a bunch of words describing the jacket, etc. like " This
reprint of the classic fourth edition, first published by Iliffe in 1953
...." and "This book is the work of 10 authors and 23 collaborating
engineers, under the editorship of F. Langford-Smith."
I am ordering mine from the source of the above info:
Opamp Technical Books
1033 N. Sycamore Ave.
Los Angeles, CA 90038
1-800-903-4567
(ask for Gary)
Can anyone in the UK verify any of this? I guess I'm from the "if it
sounds too good to be true, it usually is" school, but then again $66
smackers for a paperback ain't exactly chicken feed either! Later
Kurt
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: Radiotron Designers Handbook
Date: Wed, 22 Jul 1998 06:42:13 GMT
Source: Sound Digest Archive v01.n352
On Tue, 21 Jul 1998 21:12:36 -0500, Kurt Gabitzsch
<gabitzkw@webwide.net> wrote:
>Title: Radio Designer's Handbook (I think this is a typo, leaving off
>the "tron")
The USA version, distributed by RCA, was titled "Radiotron Designer's
Handbook," but I think that the original Australian ones from
Amalgamated Wireless were indeed titled simply "Radio Designer's
Handbook." "Radiotron" was a trademark of RCA, and that name would
not have been used in non-USA markets.
- --dnb
=========================================================================
From: "Lance Dow" <elldee@imailbox.com>
Subject: Re: Radiotron Designers Handbook
Date: Wed, 22 Jul 1998 07:58:38 +0100
Source: Sound Digest Archive v01.n352
On 21/07/98, at 22:28, Kurt Gabitzsch wrote:
>Gang - it appears that the 4th addition of the Radiotron Designers
>Handbook is being reprinted effective this month. The details as they
>have been provided to me are:
>
>ISBN: 0750636351
>Title: Radio Designer's Handbook (I think this is a typo, leaving off
>the "tron")
The copy of the 4th edition that I have is called the Radio Designer's Handbook. According to the Fo
reward, Radiotron is the name it was published with in Australia.
I do vaguely remember it being reprinted last year, a limited edition with the price around 60UK pou
nds.
Regards
Lance
=========================================================================
From: Richard C Nevill <rnevill@is.dal.ca>
Subject: Re: Radiotron Designers Handbook
Date: Wed, 22 Jul 1998 12:08:56 -0300 (ADT)
Source: Sound Digest Archive v01.n352
On Wed, 22 Jul 1998, Lance Dow wrote:
> On 21/07/98, at 22:28, Kurt Gabitzsch wrote:
>
> I do vaguely remember it being reprinted last year, a limited edition with the price around 60UK p
ounds.
And something about the warehouse they were stored in burning or flooding
or some such disaster before they got shipped for retail.
Cheers
Richard Nevill
>
> Regards
>
> Lance
>
>
=========================================================================
From: "Hubert M. Bath" <bathh@theriver.com>
Subject: Re: Radiotron Designers Handbook
Date: Wed, 22 Jul 1998 08:23:39 -0700
Source: Sound Digest Archive v01.n353
My copy of the "Radiotron Designer's Handbook" fourth Ed, says "Reproduced
and Distributed by RCA Victor Division of Radio Corp of America, Harrison,
NJ. Original was dated 1952 and published by Wireless Press for
Amalgamated Wireless Valve Co Pty, Ltd, Sidney, Australia.
More to the point. The index has a single listing under "transistor".
This listing, in its entirely, is
"Transistors are crystal devices with three or more electrodes which are
capable of amplifying. A good introductory article is Ref 86. See also
ref .................."
[Transistors were invented/discovered on 17 December 1947.]
Regards, Hu Bath
: Kurt Gabitzsch <gabitzkw@webwide.net> worte:
> Gang - it appears that the 4th addition of the Radiotron Designers
> Handbook is being reprinted effective this month. The details as they
> have been provided to me are:
>
> ISBN: 0750636351
> Title: Radio Designer's Handbook (I think this is a typo, leaving off
> the "tron")
> Org Code: MTHK
> Main Author Surname: Langford-Smith
> Publication Date: 30/07/1998
> Country of Origin: United Kingdom
> Pages: 1498
> Edition: 4th
> Line Illustrations: 920 line illustrations
> Product Type: Paperback
> Price: L35.00, US $66.95, AUS$125.00
>
> There is then a bunch of words describing the jacket, etc. like " This
> reprint of the classic fourth edition, first published by Iliffe in 1953
> ...." and "This book is the work of 10 authors and 23 collaborating
> engineers, under the editorship of F. Langford-Smith."
>
> I am ordering mine from the source of the above info:
>
> Opamp Technical Books
> 1033 N. Sycamore Ave.
> Los Angeles, CA 90038
> 1-800-903-4567
> (ask for Gary)
>
> Can anyone in the UK verify any of this? I guess I'm from the "if it
> sounds too good to be true, it usually is" school, but then again $66
> smackers for a paperback ain't exactly chicken feed either! Later
>
> Kurt
>
=========================================================================
From: "Hubert M. Bath" <bathh@theriver.com>
Subject: Re: Radiotron Designers Handbook
Date: Wed, 22 Jul 1998 08:38:40 -0700
Source: Sound Digest Archive v01.n353
Jon Lane commented to
>
> > Gang - it appears that the 4th addition of the Radiotron Designers
> > Handbook is being reprinted effective this month.
> > Price: L35.00, US $66.95, AUS$125.00
>
> Sorta blows a hole in all the guys trying to get $250US for their old
> copies...paid ten bucks for mine. =o)
>
******************
Someone is asking for some profit on the exchange rates. L35. converts to
$US56.70 and $(Aus)91.45 at exchange rates in effect 21 July 1998
Regards, Hu Bath
=========================================================================
From: Tommy Robinson <tommy_robinson@yahoo.com>
Subject: Radiotron Designer's Handbook, Fourth Edition, I want 1
Date: Sun, 18 Oct 1998 06:11:07 -0700 (PDT)
Source: Sound Digest Archive v01.n457
I want to aquire a copy of the Radiotron Designer's Handbook, Fourth
Edition. I thought I saw a post about a reprint. Was that my
imagination? I have found several original copies at
http://www.abebooks.com/. Any other suggestions would be appreciated.
Thanks,
Tommy
_________________________________________________________
DO YOU YAHOO!?
Get your free @yahoo.com address at http://mail.yahoo.com
=========================================================================
From: "Gary Bronner" <gbron@worldnet.att.net>
Subject: Re: Radiotron Designer's Handbook, Fourth Edition, I want 1
Date: Sun, 18 Oct 1998 12:16:57 -0400
Source: Sound Digest Archive v01.n458
The reprint is available.
From the web page of the publisher, Butterworth-Heinemann
http://www.bh.com/register/us/index.htm
Radio Designer's Handbook Fritz Langford-Smith US$66.95 0 7506 3635
1
I bought one from Barnes and Noble on line at
http://www.barnesandnoble.com/ . A quick search with Langford-Smith
as author and Radiotron as the subject turned it up as in stock last
week. They sold me a copy for 30% off of the list price. Shipping
and taxes add another few dollars. I tried the same thing right now
and don't seem to find it. If you are in a hurry buy it from the
publisher. If you can wait, then a little patience can save you some
money with the online bookstores. Even it doesn't show up on their
web page, you might be able to get them to special order it.
- ---Gary
- -----Original Message-----
>
>I want to aquire a copy of the Radiotron Designer's Handbook, Fourth
>Edition. I thought I saw a post about a reprint. Was that my
>imagination? I have found several original copies at
>http://www.abebooks.com/. Any other suggestions would be
appreciated.
>
>Thanks,
>
>Tommy
=========================================================================
From: "Martin E. von Lindenberg" <mvon@pop.erols.com>
Subject: Re: Radiotron Designer's Handbook, Fourth Edition, I want 1
Date: Sun, 18 Oct 1998 16:56:51 -0400
Source: Sound Digest Archive v01.n458
At 12:16 PM 10/18/98 -0400, you wrote:
>The reprint is available.
>From the web page of the publisher, Butterworth-Heinemann
>http://www.bh.com/register/us/index.htm
>Radio Designer's Handbook Fritz Langford-Smith US$66.95 0 7506 3635
>1
>
I emailed Amazon w/ the info, and asked them if they could make it
available at a discount. I'll let you know their reply.
Martin
Mvon@erols.com
=========================================================================
From: "Riesz, Ted - PETFISH" <Ted.Riesz@mailhost.dpie.gov.au>
Subject: RE: Radiotron Designers Handbook now swap RD3
Date: Wed, 22 Jul 1998 16:11:21 +1000
Source: Sound Digest Archive v01.n352
This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.
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Content-Type: text/plain
Hi
While we are on the subject of the RD4, I have a spare copy of the
earlier RD3 in reasonable condition which I would be prepared to swap
for another book or other tube stuff.
This version predated the RD4, and while much thiner and not containing
all the info in RD4, never the less is useful in its own right
containing some SE stuff not covered in the later RD4.
Offers?
Regards
Ted Riesz
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=========================================================================
From: "Ken Dangerfield" <bpyakd@mail.island.net>
Subject: Re: Radiotron Designer's Handbook on CD-ROM??
Date: Wed, 11 Mar 1998 23:41:06 -0800
Source: Sound Digest Archive v01.n215
Available from Old Colony (custserv@audioxpress.com) or the recently
maligned Parts Connection (tpc@sonicfrontiers.com) for $69.96US.
Regards,
Ken Dangerfield
On 12 Mar 98 David Suess said:
> > Also, you might want to get a copy of "Radiotron Designers Handbook"
> > (which I understand is available on CD-Rom now), as well as lots of good
> > tube design info, it has a nice section on transformer theory and
> > design.
>
> Anybody know where this can be purchased? How much?
>
> +-------------------------------------------------------------------+
> | david suess (david.suess@medtronic.com) |
> | minneapolis, minnesota |
> +-------------------------------------------------------------------+
>
>
=========================================================================
From: Grover Gardner <groverg@postoffice.att.net>
Subject: Re: Radiotron Designer's Handbook on CD-ROM??
Date: Thu, 12 Mar 1998 12:25:55 -0600
Source: Sound Digest Archive v01.n215
At 10:49 AM -0600 3/12/98, David Suess wrote:
>As Thomas Danley writes:
>>
>> Hugh Dean wrote:
>>
>> Also, you might want to get a copy of "Radiotron Designers Handbook"
>> (which I understand is available on CD-Rom now), as well as lots of good
>> tube design info, it has a nice section on transformer theory and
>> design.
>
>Anybody know where this can be purchased? How much?
RDH #4 is also available in print for about $80, you can order from Borders
or Barnes and Noble or whatever. Personally I'd prefer this, since you can
take it to bed with you at night for "light" reading :-). I'm expecting a
copy for my birthday in May...
=========================================================================
From: David Suess <ds10760@doc.medtronic.com>
Subject: Radiotron Designer's Handbook on CD-ROM??
Date: Thu, 12 Mar 98 10:49:50 CST
Source: Sound Digest Archive v01.n215
As Thomas Danley writes:
>
> Hugh Dean wrote:
>
> Also, you might want to get a copy of "Radiotron Designers Handbook"
> (which I understand is available on CD-Rom now), as well as lots of good
> tube design info, it has a nice section on transformer theory and
> design.
Anybody know where this can be purchased? How much?
+-------------------------------------------------------------------+
| david suess (david.suess@medtronic.com) |
| minneapolis, minnesota |
+-------------------------------------------------------------------+
=========================================================================
From: Thomas Dunker <dunker@invalid.ed.unit.no>
Subject: Ragnar Lian's articles
Date: Mon, 4 Jan 1999 21:38:43 +0100 (CET)
Source: Sound Digest Archive v01.n558
Hello all joenetters, old and new. As you may know (or not, or just
sigh at) I find the subject of speaker distortion and ways to reduce it
VERY FASCINATING (more so than building and listening to tube amps, even).
A while back, I believe I shared with you some translations and/or
adaptations of some old articles written by our (Scandinavian) local
hero of speaker design/understanding, Ragnar Lian. He's inspired me
before, and he does it again these days with some very intriguing and
inspirational postings on the Norwegian newsgroup no.audio, in response to
someone's curiousity regarding current drive of speakers.
If any of you people paid attention to all my past raves on these subjects,
you will see that Ragnar sums up many of the things I've been trying to
summarize myself. He does it way better, though. But some "new" things may
be of universal interest, as when Ragnar explains "alnico sound", in the
text below (which I hastily translated from Norwegian this afternoon,
please pardon the lack of lingual refinement and listen to this aging
man instead).
I can probably not blame any of you for not knowing who Ragnar Lian is or
what he's contributed to the field of audio and speakers in partcular.
But he can look back at half a lifetime's involvement in the speaker
research and industry, having worked with Tandberg, Radionette, Seas,
Bang & Olufsen, and co-founder of Scan-speak, affiliation with Dynaco
and numerous other audio companies etc. etc. He now works designing
industrial magnetics for a Norwegian firm called Contec Design
(CT-scanners and such). It's a shame he's not a member here, really.
Personally I think the below text (directly translated from three
successive postings to no.audio) is packed full with stuff that should
send people like us scrambling to the drawing board/shop/think tank,
whatever...or at least rob us of *some* peace of mind and induce some
humbleness with respect to the goals we all pursue in some way or other.
If he repeats something, it's for a reason, so read it and THINK!
Here we go:
Oh, my - granddad Lian feels touched. Words about current-drive sound like
music to my ears, and it's about time! So...one problem will naturally
appear, the damping factor! But what IS that? It's a wool blanket we
hang in front of the speaker to obscure the mechanics. A loudspeaker is
a piece of mechanics! Those who can't picture mass and springs physically
may look at the speaker's equivalent diagram, where BxL forms a feedback
loop. It does the exact same thing as in amplifiers by producing pretty
measurement data for an unconscious pig-design. It does nothing wrong, but
it obscures a problem.
Same thing with the damping factor - it doesn't do anything wrong, but
it provides an acceptable frequency response curve for a poorly designed
bass speaker. An oscillating circuit consisting of a weight and a spring
stores energy, and if this energy is not absorbed mechanically or is
minimized in the acoustic design, it will be sent back to the amplifier
at the most bizarre points in time. Wasn't it the good old NS-1000 that
sent 40 amp spikes back to the amp, paralyzing it? I have a dim
recollection of a demo by Otala some time in the late 70's, where one of the
most respected amps was loaded by an 8 ohm resistor and an NS-1000,
respectively. The amp's output was coupled to a tape recorder. At the
demo, this tape was played back, with the recorded difference of the
two different loads. The difference was like night and day!!!!!
The moral is: A speaker should be loaded in a controlled manner,
that is, resonances and other tendencies of energy storage should be
treated where they appear, not hidden by the damping factor. When a
speaker is properly loaded, the damping factor naturally doesn't do
any harm, but doesn't improve anything either! If one is short of ideas,
examine patents from 1925 up to about 1950, back then the problems
had to be solved without the aid of damping factor, which meant that
there was no other way than fixing the problems where they originated.
Lots of more or less intelligent patents.
Ragnar Lian
Date: Thu, 22 Oct 1998 11:21:48 +0200
I have received some response to my posting on this subject a week
ago, and some questions of "how to do it? " have appeared. There is
no simple answer, it has more to do with a mindset and "programming".
Some times it may be necessary to take a step back, not to stay there,
but to get a better overview.
In the sixties, some idiot took the loudspeaker out of the radio.
Pretty smart, with regard to placement and furnishing, but with time it
led to a disaster. The disciplines of amp design and speaker design were
separated, with a minimum of communication between the two professional
groups. A voltage interface was defined, in which amp designers made amps
loaded by 8 ohm resistors and speaker designers made speakers based on a
source impedance of 0 ohms from the amplifier.
The amp designer, on his side, made a great effort to achieve marginal
figures of harmonic distortion into 8 ohms (0.0000001%), whereas the
speaker designer was so busy playing with Thiele/Small parameters and
theoretically flat frequency response that he never had the time to
philosophize on distortion, perhaps occasionally some harmonic, but
certainly not intermodulation.
A sad, but overlooked fact is that the electrodynamic speaker is
controlled by current through a voice coil, not by a voltage across
it. As voice coils are more or less filled by solid iron, this
causes a pronounced cubic current distortion, usually on the order of
0.5-5% !!!!!!
This demonstrates two things;
1: The nice distortion characteristics of the amplifiers seem wasted,
as the driving current is distorted by iron in the magnetic system,
but, 2: It can still be heard that the amplifier has been improved far
below the level masked by speaker distortion. This shows that
distortion measurements by themselves don't say everything about
sound quality, rather that it is the TYPE of distortion mechanism we hear.
This is encouraging!
But now, if we had an amplifier that provided undistorted current
rather than undistorted voltage, we would have achieved a
drastic improvement of the total distortion.
The paradox is that the loudspeaker is controlled by current, and the
amplifying elements, whether tubes or transistors, are by nature
current generators. There's ALWAYS anode CURRENT, collector CURRENT and
drain CURRENT which is being controlled. Using various components and
trick circuits this is converted to a varying voltage which is
supplied to the speaker, where the driving current is strongly distorted
by an iron filled voice coil.
Pages can be written about distortion mechanisms in loudspeakers,
this I will skip this time, instead I have a small digression about
transistors. Has anyone pondered why it's called emitter, base and
collector? See, when the transistor was developed it proved to be a
current controlled device, actually it was a diode consisting of
collector and base, and with the emitter a current was injected,
emitted into the PN layer between collector and base, and a larger current
variation ocurred between collector/base than the injected
emitter/base current. The first germanium transistors were PNP, an
amplifier was drawn with the base upwards from ground like a T,
the collector was connected to - (minus) (here, + was connected to
ground), and a - (negative) signal current was injected into the emitter,
the arrow pointing inwards.
Note that I am not saying that this is the only right hookup, but
some weakly programmed engineers should allow themselves to think
the thought, perhaps even process it. Some really fine transistors
with linear current amplification existed around 1970, wasn't it the
D44 and D45 series from General Electric, perhaps they have gone
into hibernation in some corner at HARRIS ?
You can't make current controlled speakers and current amps just like that,
and make them communicate. For 40 years we have been strictly indoctrinated
as to what was correct, and the whole design philosophy both in
speaker design and amp design is based on "the way" ! This will take time
and effort to change.
Regarding speaker design: we need some communication between disciplines.
Tor Forsman's demo at the AES meeting showed that not only the classical
radiation impedance is important, but that this can be supplemented
by aerodynamics. Isn't there an airplane designer with a passion for
loudspeakers somewhere? It's nothing mystical, just a different
discipline.
For the impatient - the introductory question - yes, it's possible to
get started. You take a super high current op-amp such as LM12, and
make a current feedback loop around it. This will not be a hi-fi amp,
but is a good start for observing effects.
Regarding current controlled speakers, there's a bunch of creative
patents from the 1925-1950 period, when practically all amps were
high impedance and thereby current generators.
And a little warning, particularly in loudspeakers there are many
distortion mechanisms at work simultaneously, which in part of the
frequency range are in opposite phase. Therefore one may experience that
when one distortion mechanism is removed or reduced, a higher total
distortion will be measured while the speaker sounds cleaner.
Is it possible to stir anyone's curiosity?
Ragnar Lian
Subject: Vårluft om høsten/current drive
Date: 26 Oct 1998 22:04:20 GMT
I'm thankful for the response which has been mixed and diverse, and which
partially calls for a little more information on the matter.
Some have also mentioned servo controlled speakers. I'll treat this first,
as it's a fairly concrete matter. I would not say that they don't work,
I struggled with them a great deal in the mid-70's. It worked nicely
at bass frequencies. If you tried to push the cone inward, it struggled
to oppose this motion, using all the power available from the amplifier.
But it had its cost: Nice deep bass, but rotten midbass. This was because of
phase shift in the servo loop, popularly speaking: the problems were
shifted upwards to a higher frequency. The conclusion back then was that
it was better to use money and resources to improve the driver units
themselves. Philips did market some motional feedback speakers, but they
sounded unmistakably like Philips!
Now, back to the real issue, current driving speaker units. I don't have
any simple recipes, for the simple reason that this has been a non-issue
the past 40 years. Current drive is not the sole solution either,
but it's practically necessary to go this way in order to understand how
a speaker works, then go on to design drivers with improved properties.
Looking at today's speaker units, one is amazed that they don't sound
a lot worse, they're packed full of mistakes.
The reason why I bring this forth on the net instead of designing and
getting rich myself is that I'm beginning to get old, and have a list that
it would take half a lifetime to follow up. And when I say "tease somebody's
curiosity" it's not because I have exciting completed stories to tell,
but because I have lists of interesting problems that should be solved
by those crazy enough to do so. Developing "canned music" requires,
apart from a certain amount of theoretical knowledge, musicality,
freedom from prejudice and a dose of insanity!
The perfect speaker is absurd, and will only be created in advertisements,
but a huge potential for improvement exists compared to what we've seen
the past 25 years. It was tremendously exciting when Benson, Thiele and
Small presented their calculation models for loudspeaker enclosures, and they
helped understanding bass reflex enclosures in particular. But at the same
time something like a blockage was introduced, as everything circled around
these transfer functions, and the computational models for the speaker were
adapted to these functions. In itself nothing wrong, but it caused
everything not described by these models to be regarded as nonexistent !!!!!!
But now back to my list of problems and paradoxes:
1: Current drive vs. voltage drive:
The force generated by the voice coil is equal to B x I x L, where B is the
magnetic field, I = voice coil current and L = effective length of wire
in the magnetic field. We struggle to make an amplifier with extremely
low distortion, and then the force from the voice coil, caused by the
current through it, is dramatically distorted (0.5-5%) because the coil
is partially filled with iron, which has eddy currents and hysteresis
losses which in turn cause distortion.
Furthermore, the coil has a self-induction that causes a slower buildup of
current and thereby a time delay or loss at higher frequencies. Furthermore
this self-inductance is dependent on the amount of iron within the coil,
and will vary when the coil moves. This causes intermodulation, as a
lower frequency that produces a fair amplitude will modulate a higher
frequency. (As far as I recall, the woofer of the AR3A modulated a 600Hz
tone by 50% (!!!!!!) when it was supplied with a 20 Hz tone at nominal power.)
Also, the voice coil gets warm, and the resistance increases by 0.4% per
degree celsius so that the current, and thereby the output drops
correspondingly. Typically this causes a compression on the order of 4-6 dB.
If the speaker is driven by a pure current rather than a pure voltage,
these effects disappear or are dramatically reduced.
(Symmetric drive, a copper cylinder long enough to short the voice coil in
all positions, was my answer to these problems associated with voltage drive,
and was used by Scanspeak from 1973 on, and by Dynaudio since 1976.
The system was not perfect, but gave an improvement by a factor of 3-10.)
If one thinks that introducing current drive fixes everything, one is
stuck in the glue. Since 1960 we have been accustomed to "pig design" a
loudspeaker's acoustic rear load, the damping factor has concealed our
lousy craftsmanship. Here I thought of the old patents from the midwar
years. Not to rehash them, but the idea was to make rear loads which
reduced or eliminated the speaker's resonance, that is, that the mechanical
system was damped in itself.
I would like to highlight a Carlisle patent from about 1930, describing
all conceivable variations of enclosures with coupling ports/slits to
free air or to one or several separate chambers - a wellspring of ideas
and a valuable aid each time one ends up in an argument with someone or
other who's reinvented something.
2: Modulation of the magnetic field.
This is a neglected area. In the 50's they philosophized a great deal
over why the voice coil was displaced in the magnetic field under
conditions of strong drive, among other things Cunningham defined
the "solenoid effect". If one takes the trouble to measure the force from
the voice coil inwards and outwards respectively, at say an applied
coil current of five amps, one will realize that there is a large
difference. The coil pushes harder outwards than it pulls inwards.
Somewhat dependent on the design, this difference will be on the order
of 5-50% (!), causing both offset and compression.
I have, just to tease, done calculations on three different magnet
systems; my old Scanspeak system with 18 mm coil, 100 windings and
a 120 mm ferrite magnet, but without SD (Symmetric Drive). Then an
imagined system with a 40mmx40mm alnico magnet, and one system with
a 40x10 neodymium magnet. These three systems have roughly the same
magnetic field, statically speaking. The ferrite system has an
asymmetry of 25%, the alnico system has 4% and the neodymium system
at about 2% ! Mysterious? Not at all! If we picture the voice coil,
18 mm long, 100 turns, at 5 amps, this produces 500 amp-turns, or
a field strength of 28000 A/m, this is a magnet "let loose" around
the air gap. It is directed with or in opposition to the main field,
depending on the direction of the current, and acts directly upon the
field in the air gap, and also shifts the operating point of the
magnet. The ferrite magnet's operating point is at about 2500 gauss,
and has an incline such that it can easily be shifted 2-300 gauss,
that's quite a few per cent! Both the alnico magnet and the neodymium
magnet have operating points up around 10-11000 gauss, and an incline
which makes them somewhat "stiffer", meaning that they can't be
moved much. Both neodymium and alnico have the property of having
a permeability close to 1, in other words the same as air, and they do not
affect the inductivity of the voice coil! Then we can go back to the
early 70's, when JBL spoke of "The Alnico Sound" - that was no lie!
3: The loudspeaker as accumulator of energy:
All reactive components, both electric and mechanic, store energy. This
energy is converted to electric or acoustic energy at a point in time
over which one has no control. The ideal speaker has neither mass nor
springs, self-induction or capacitance. Therefore the ideal speaker
doesn't exist, but we don't have to remove it as far as possible from the
ideal. Low mass, compliant suspensions and low voice coil inductance.
All of this about speakers, and I have barely touched the voice coil.
No solutions, just a lot of exciting work, for those crazy enough!
I don't have a lot of experience with amp design, but it should basically
be easier to make a current amplifier than a voltage amplifier, if we
disregard the past 40 years of programming. Even though telephone
technology is primitive with regard to distortion and frequency response,
I believe there is a great deal to learn from it in terms of methods.
It's really impressive, before satellites one could phone all across the
world over a pair of twisted wires thanks to current-based technology.
That never would have worked with voltage!
Ragnar Lian
- -- end of forwarded message --
- -------------------------------------------------------------------------
_/\_ Thomas Dunker \ The Horn Speaker Home Page:
/ \ P.O.Box 2811 \ http://invalid.ed.ntnu.no/~dunker/horns.html
| | 7002 Trondheim \
| | NORWAY \--\ "Those with head above water
\____/ dunker@omegav.ntnu.no \ see only the tip of the iceberg"
|||| phone (+47)73916898 \ (Gene Dalby)
- ------------------------------------------------------------------------
- -------------------------------------------------------------------------
_/\_ Thomas Dunker \ The Horn Speaker Home Page:
/ \ P.O.Box 2811 \ http://invalid.ed.ntnu.no/~dunker/horns.html
| | 7002 Trondheim \
| | NORWAY \--\ "Those with head above water
\____/ dunker@omegav.ntnu.no \ see only the tip of the iceberg"
|||| phone (+47)73916898 \ (Gene Dalby)
- ------------------------------------------------------------------------
=========================================================================
From: "Reid Welch" <rewelch@earthlink.net>
Subject: Random exclusions?
Date: Sun, 20 Sep 1998 21:56:52 -0400
Source: Sound Digest Archive v01.n427
I'm able to post again- without knowing what it was that kept my letters off
the list for over a week.
Now Dave Slagle reports via private mail that he now has the same trouble.
The heartbreak of *Nonpostititis*
Tomorrow it may afflict YOU.
What is the cause and cure?
in vacuo,
Reid
=========================================================================
From: sschenkel@juno.com
Subject: Raven R-2
Date: Wed, 9 Dec 1998 12:52:53 -0800
Source: Sound Digest Archive v01.n532
Mike I just spoke to Elliott. He tells me that Kemon Bellas at Orca is
having two designs worked on for the Raven R-2 tweeter. One is with the
8 inch Cabasse woofer, and the other with a Focal 7" DVC woofer. They
should be done in Janurary. This might be a food reason to pick up the
Ravens while they are on sale. I am going to post this to the list.
Steve Schenkel
=========================================================================
From: sschenkel@juno.com
Subject: Re: Raven R-2
Date: Thu, 10 Dec 1998 12:18:47 -0800
Source: Sound Digest Archive v01.n533
Zalytron. $275.00 regular $350.00 it's a factory authorized sale.
On Thu, 10 Dec 1998 12:32:21 -0600 Gab <gabitzkw@webwide.net> writes:
>Who has the R2 on sale (Zalytron?) and how much?
>
>Kurt
>
>
Steve Schenkel
=========================================================================
From: Gab <gabitzkw@webwide.net>
Subject: Re: Raven R-2
Date: Thu, 10 Dec 1998 12:32:21 -0600
Source: Sound Digest Archive v01.n533
Who has the R2 on sale (Zalytron?) and how much?
Kurt
sschenkel@juno.com wrote:
> Mike I just spoke to Elliott. He tells me that Kemon Bellas at Orca is
> having two designs worked on for the Raven R-2 tweeter. One is with the
> 8 inch Cabasse woofer, and the other with a Focal 7" DVC woofer. They
> should be done in Janurary. This might be a food reason to pick up the
> Ravens while they are on sale. I am going to post this to the list.
>
> Steve Schenkel
=========================================================================
From: Miguelito <mbarrio@midway.uchicago.edu>
Subject: Re: RB300 Rewire
Date: Fri, 20 Mar 1998 08:51:25 -0600 (CST)
Source: Sound Digest Archive v01.n223
Hi,
> Anyone know where I could find information/tips on rewiring the RB300
> tonearm? Iwas going to dive in but thought it best to seek some
> advice....I am using the Discovery cable.
I rewired my RB-250 arm and the difference in sound was staggering. I'm
including a file which has the reference to the basic article (available on
the web) as well as my own experience.
Miguel
- --
Miguel Barrio "Charm is a way of getting the
mailto:miguelito@pobox.com answer yes without asking a
http://pobox.com/~miguelito clear question." -- Albert Camus
=========================
Hi all!,
After reading the 'Hot Wired Rega' article on the net (at
http://www.hi-fi.com/diy/rega/ ) I decided to take a peek at how the wire was
connected at the base of my RB-250 tonearm. Well... my curiosity is
stronger than my common sense so I did it and busted the original
cables... duh!
Anyway, this forced me to go through the rewiring process. Instead of using
what's suggested in that article I used Cardas wiring throughout and
Vampire interconnects reducing the parts cost to $55. Pretty good, ah?!
The reason I'm posting here is because I think that the mentioned article
lacks some detail in some very important issues as well as having made a
GROSS mistake in the procedure. To be succint, the points that I consider
important are (in order of importance, 1 being VERY important):
1) DON'T throw away the circuit board that on the plastic cap. It can be
easily and cleanly taken off the cap and reused. Why? The article has the
cables sticking into the arm's base. It also says that the author could
SENSE SOME TORQUE PRODUCED BY THESE BUNCHED CABLES!!! This is BAD. Even not
'sensing' any torque with the bare hand isn't good enough (can anyone
'sense' the antiskating force???). Keeping the circuit board and using it
in the original configuration is a MUCH better idea (and it's easy
too). The finished connector looks exactly like the original Rega's with
the difference that the wiring is *so* much better (and the connection is
now balanced).
2) It's important to adjust the outgoing cable's angular position so that
one gets zero antiskating force when it's slide control is set to zero.
After finding this position one can tighten up the set screw.
3) It's easier to make a grounding contact on top of the tonearm opening
instead of the bottom. Moreover, it's better to have some wire mesh instead
of just some thin wire making the contact (you can solder the ground wire
to this wire mesh).
4) It's good to have some strain relief heat shrink covering the cartridge
clips.
These are the main points that I changed from the original procedure.
Actually, nothing is mentioned about 2), that's my own contribution :-)
If anyone is interested in details, especially for step 1), please email me
and I will post detailed instructions for doing each part.
I want to thank the guy who wrote the original article. I do think there
are some important things to be noted around it, though. I tried to post
this to the DIY Forum in this site but couldn't.
The result soundwise? The sound improved quite a bit. It might be due to the
balanced connection (compared to the single ended configuration the arm
comes with). Maybe the quality of the wire had something to do with it
too. The bottomline is that the sound improved but it was a lot of work.
Enjoy the music!
Miguel
- --------------------------------------------------
Hi all again!,
Following up my post regarding the Rega arm rewiring, I'll give some
details on the parts that I mentioned needed modification in the original
procedure for rewiring.
> Cardas wiring throughout
33 awg tonearm wire and double conductor/double shield phono lead wire.
> Van den Hul cartridge clips
the set with heat-shrink strain reliefs.
> and Vampire interconnects
the cheapest ones (which are pretty good anyway).
> 1) DON'T throw away the circuit board that on the plastic cap. It can be
> easily and cleanly taken off the cap and reused.
Cut all wires to the plastic puck. Get a sharp utility knife and try to
(gently) slice through the space between the circuit board and the plastic,
rotating the piece of plastic (thus cutting from the inside out). If you do
this carefully you'll cut the wire that's heat molded into the plastic (or
rather the plastic is heat molded over the wire). This will allow you to
get a clean circuit board as well as a cute plastic puck.
Now with a drill drill a hole through the plastic puck (it's easy). I
drilled the hole slightly off-center so that I could get rid of all the old
wire, but this is irrelevant.
Once you've got the hole pick a conical bit (they have a special name
which I can never remember). These are used to drill conical wholes on a
piece of wood when you want a wood screw to be flushed at surface
level. There are (broadly speaking) two types of these bits: some are very
sharp and some are almost not sharp at all. USED A SHARP ONE. So, with the
bit (BE CAREFUL) drill a conical hole on the inside part of the puck. Don't
go too far, leave about 1 or 2 millimeters of flat surface at the
edges. It's safer to use a vice to hold the puck. I was afraid that my puck
would crack when I hold it with the vice, but if you're gentle this won't
be a problem.
Clean up the circuit board and solder the phono lead terminals (ie, the
thick wire that'll come out of the base of the arm) to the corresponding
holes. There's a copper thingy on the board that's connected to the left
channel's ground and the arm's ground. Desolder it and connect it just to
the arms ground. Why isn't it connected to the right channel's ground? To
prevent ground loops. The people at Rega save money but are certainly not
stupid :-). BTW, this is another flaw in the original procedure (the
copper ground).
Peel the phono lead cable and make the shields and the ground wire into one
conductor. Thread it through the whole in the center and solder it to the
ground terminal on the circuit board. Solder the wires to the five contacts
on the circuit board.
Once everything is soldered together you can gently pull from the lead wire
to get the circuit board flushed over the plastic puck. The conical hole
allows you to do this :-) . Put some 5 minute epoxy around the edges and
(using some folded paper to avoid hurting the circuit board) hold the whole
thing gently with the vice so that the epoxy hardens and you get a nice
little contact puck with beautiful wires sticking out of it 8-D .
> 2) It's important to adjust the outgoing cable's angular position so that
> one gets zero antiskating force when it's slide control is set to zero.
> After finding this position one can tighten up the set screw.
Now you have to solder the tonearm wire to the terminals on the circuit
board. I suggest that you use a pair of tweezers and hold the wire very
close to the tinned end so that the heat doesn't spoil the shielding along
the wire (the tweezers act as a heat sink).
Once you did this put the arm back on the table and the table on a leveled
surface. Adjust the antiskating slider to 0 (zero) and balance the arm wait
so that it's basically horizontal. Now put the puck (with wires attached
and all) into the base of the tonearm (be careful not to get any of the
tonearm wires caught between the arm and the metal cylinder in the
process). Rotate it so that you get to a point were the arm stands still in
some mid position between the arm rest and full-swing. Once you've done
this you can tighten up the set screw and you're done.
> 3) It's easier to make a grounding contact on top of the tonearm opening
> instead of the bottom. Moreover, it's better to have some wire mesh instead
> of just some thin wire making the contact (you can solder the ground wire
> to this wire mesh).
I don't need to explain this any further (I guess). I used a round file
instead of the unnecesarilly fancy drill used in the article.
> 4) It's good to have some strain relief heat shrink covering the cartridge
> clips.
Self-explicit.
Okdokey, this took too much time already!
Hope this helps. Enjoy the music!
Miguel
- ----------------------------------
Hi!,
I think that taking the tonearm wires all the way to the phono preamp is a
very good idea. The wires (I'm thinking of the 33 awg Cardas tonearm wire
but this applies to the 28 awg Discovery wire in the article which is
actually THICKER) won't pose a problem in terms of being too fragile.
The way I would do this is the following:
1) Get wire mesh (double the length you need from the 'table to the phono
preamp). This mesh looks like a mesh tube and it looks too big (it's
diameter). This is good because you'll have to thread the tonearm wire
through it.
2) Use two runs of this mesh, one for each channel. Thread the
corresponding wires (two per mesh) through them.
3) Once you're done, stretch the mesh by pulling (carefully) from the ends.
You'll see that it shrinks.
4) The ground wire doesn't go through the mesh but rather solder it to the
mesh at the base of the tonearm. Do this BEFORE threading the cables
through the mesh!!! Otherwise the heat will destroy the shielding of the
tonearm wires. Use a separate ground wire from the base of the tonearm to
the phono preamp. Also, don't connect the mesh to the RCAs or you'll create
a ground loop.
5) Use some heat shrink over the mesh at the base of the tonearm, and once
the heat shrink is shrunk, epoxy it to the plastic puck so that it's firmly
attached to it.
Hope this helps!
Miguel
=========================================================================
From: Scott Emery <semery@ctrpoint.com>
Subject: RB300 Rewire
Date: Fri, 20 Mar 1998 09:30:50 -0500
Source: Sound Digest Archive v01.n223
Anyone know where I could find information/tips on rewiring the RB300 tonearm? Iwas going to dive in
but thought it best to seek some advice....I am using the Discovery cable.
Thanks,
Scott Emery
=========================================================================
From: Kalman Rubinson <rubinsnk@is2.nyu.edu>
Subject: Re: RB300 Rewire
Date: Fri, 20 Mar 1998 11:05:58 -0500 (EST)
Source: Sound Digest Archive v01.n223
On Fri, 20 Mar 1998, Scott Emery wrote:
> Anyone know where I could find information/tips on rewiring the RB300 tonearm? Iwas going to dive
in but thought it best to seek some advice....I am using the Discovery cable.
Try:
http://www.hi-fi.com/diy/rega/
Kal
=========================================================================
From: Grover Gardner <groverg@postoffice.att.net>
Subject: Re: RCA 845's?
Date: Tue, 6 Oct 1998 13:59:08 -0500
Source: Sound Digest Archive v01.n443
At 7:16 PM +0200 10/6/98, Kurt Steffensen wrote:
ese are not at all suitable for audio.
>
>The Chineese 845´s are really good stuff.
>So are their 211´s.
Ditto. A friend uses Chinese 845s in PP for 130 watts. He has had no
problem with them after a year and feels that the sound is comparable to
NOS. I don't think you need to derate them...
Grover Gardner
groverg@postoffice.att.net
=========================================================================
From: Kurt Steffensen <solvin-aurum@get2net.dk>
Subject: Re: RCA 845's?
Date: Tue, 06 Oct 1998 19:16:40 +0200
Source: Sound Digest Archive v01.n443
Jeff Brouwer wrote:
>
> Hi all,
>
> I just ordered some RCA 845's that, from the price, I assume are
> chinese (60 USD). Anyone heard of RCA doing this? The gentleman I
> spoke with indicated that the tubes are new--is RCA still in the
> business of supplying transmitting tubes?
>
> Anyone have any recommendations on how much to derate chinese 845's in
> order to get reasonable reliability?
>
> Thanks in advance.
>
> -jeff
Hi Jeff.
RCA is not in the tube buisness anymore.
Transmitting tubes are still being produces in the USA.
But these are not at all suitable for audio.
The Chineese 845´s are really good stuff.
So are their 211´s.
However must of the Chineese tubes are junk...
- - Kurt
=========================================================================
From: "Jeff Brouwer"<jbrouwer@mail.crc.com>
Subject: RCA 845's?
Date: Tue, 06 Oct 98 12:54:43 -0500
Source: Sound Digest Archive v01.n443
Hi all,
I just ordered some RCA 845's that, from the price, I assume are
chinese (60 USD). Anyone heard of RCA doing this? The gentleman I
spoke with indicated that the tubes are new--is RCA still in the
business of supplying transmitting tubes?
Anyone have any recommendations on how much to derate chinese 845's in
order to get reasonable reliability?
Thanks in advance.
-jeff
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: RCA 845's?
Date: Wed, 07 Oct 1998 00:15:46 +0200
Source: Sound Digest Archive v01.n443
>The Chineese 845´s are really good stuff.
>So are their 211´s.
>
>However must of the Chineese tubes are junk...
I think some relevant distinction betwen all those Cinese Manufacturers
might be in place
Golden Dragon, as an example, has a decent product range nowadays. Good
sounding tubes, with consistent sound over time. No problem like they used
to have and a rugged (and well sounding) KT88
Their 211's are pretty god as well, as are their ECC tubes and the new
"euro" EL34: Value for money !
I do not have broad experience with other manufacturers, but I here good
and bad news as well.
regards,
>- Kurt
>
>
=========================================================================
From: Ishmael349@aol.com
Subject: RCA/Ampex 300 for sale
Date: Wed, 16 Dec 1998 10:49:54 EST
Source: Sound Digest Archive v01.n541
Ampex 300, 1/2 inch, 2-track (conversion from 3-track), 15/30ips. Origional
RCA field recorder. This is THE machine used to record Elvis, Belafonte at
Carnegie Hall, Horiwitz, Weavers at Carnegie etc. Completely serviced by RCA
engineers. This unit has several RCA mods to improve its performance and ease
of handling. Very beautiful piece of industrial art. Works perfect. $2000 +
shipping
Geranium transistor electronics (2-channels) $1500 or $1000 with above
machine.
Call Herb at 718.876.9742 or e-mail: Ishmael349@aol.com I only want to sell
this machine to someone who really appreciates what this is and whata bargan
it is.
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: RCA/Ampex 300 for sale
Date: Wed, 16 Dec 1998 12:57:26
Source: Sound Digest Archive v01.n542
A 10:49 AM 12/16/98 EST, Ishmael349@aol.com a écrit :
>
>Geranium transistor electronics (2-channels) $1500 or $1000 with above
>machine.
I hope the geranium transistor circuitry is potted.
dbk
=========================================================================
From: Christian Rintelen <rintelen@datacomm.ch>
Subject: Re: RCA/Ampex 300 for sale
Date: Wed, 16 Dec 1998 19:41:22 +0100
Source: Sound Digest Archive v01.n542
Ishmael349@aol.com wrote:
> Geranium transistor electronics (2-channels) $1500 or $1000 with above
> machine.
What does a Geranium transistor produce -- flower power?? Christian ;-)
=========================================================================
From: Joseph Lowe <jlowe@cdc.net>
Subject: Re: RCA/Ampex 300 for sale
Date: Thu, 17 Dec 1998 09:32:15 -0500 (EST)
Source: Sound Digest Archive v01.n542
On Wed, 16 Dec 1998, Christian Rintelen wrote:
> Ishmael349@aol.com wrote:
>
> > Geranium transistor electronics (2-channels) $1500 or $1000 with above
> > machine.
>
> What does a Geranium transistor produce -- flower power?? Christian ;-)
>
boo - HISS
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: RCA/Ampex 300 for sale
Date: Thu, 17 Dec 1998 18:53:17 +0100
Source: Sound Digest Archive v01.n543
At 19:41 16-12-98 +0100, Christian Rintelen wrote:
>Ishmael349@aol.com wrote:
>
>> Geranium transistor electronics (2-channels) $1500 or $1000 with above
>> machine.
>
>What does a Geranium transistor produce -- flower power?? Christian ;-)
What is wrong with germanium ?
Guido
=========================================================================
From: Richard C Nevill <rnevill@is.dal.ca>
Subject: RCA Phono Preamp
Date: Thu, 18 Sep 1997 15:41:32 -0300 (ADT)
Source: Sound Digest Archive v01.n030
Hi y'all
Since there has been some talk about this circuit I'm wondering if
anyone has actually built and used it. Looks pretty simple to build but
how does it sound? Kinda a vague question I know but i'm interested in
opinions on this unit.
Cheers
Richard Nevill
=========================================================================
From: match@ee.utah.edu
Subject: Re: RCA Phono Preamp
Date: Fri, 19 Sep 1997 08:38:31 +0000
Source: Sound Digest Archive v01.n031
If you're talking about the one in the RCA tube handbook, I built it
in 1969. It was easy to get going, I used it for 2 years or so 'til I
went into the military, then a couple after. As I recall, I liked it,
but of course that was... what... 28 years ago? Am I really that
OLD???
Marvin
match@ee.utah.edu
> Hi y'all
>
> Since there has been some talk about this circuit I'm wondering if
> anyone has actually built and used it. Looks pretty simple to build but
> how does it sound? Kinda a vague question I know but i'm interested in
> opinions on this unit.
>
> Cheers
>
> Richard Nevill
>
>
>
>
>
=========================================================================
From: Richard C Nevill <rnevill@is.dal.ca>
Subject: RCA phono stage
Date: Thu, 18 Sep 1997 17:37:06 -0300 (ADT)
Source: Sound Digest Archive v01.n030
Since there has been some talk about this circuit I was wondering if
anyone has built and used this thing. How does it sound? Is it easy to
build (it does look fairly easy). Interested in some opinions to see if it
is worth collecting parts and trying this fellow
Cheers
Richard Nevill
=========================================================================
From: "Chris Beck" <cbeck@brewercompany.com>
Subject: Re: RCA Phono Stage Current Demand
Date: Tue, 20 Oct 1998 07:44:50 -0500
Source: Sound Digest Archive v01.n461
I don't have the exact numbers, but it's not more than a few milliamps per
channel. The 12AX7's run VERY cool.
Chris Beck
See my web page at: http://www.execpc.com/~n9zes/index.htm
- ----------
> From: Ang Fui Gan <ang@ermsg.com>
> To: joe <sound@deliverator.io.com>
> Subject: RCA Phono Stage Current Demand
> Date: Tuesday, October 20, 1998 2:25 AM
>
> Hi there,
> Anyone knows how much current the RCA
> phono draws?
> FG
>
=========================================================================
From: "Ang Fui Gan" <ang@ermsg.com>
Subject: RCA Phono Stage Current Demand
Date: Tue, 20 Oct 1998 15:25:47 +0800
Source: Sound Digest Archive v01.n461
Hi there,
Anyone knows how much current the RCA
phono draws?
FG
=========================================================================
From: Chris Galbraith <chrisg@ducker.com>
Subject: RCA Phono stage EQ questions...
Date: Tue, 25 Nov 1997 08:43:12 -0500
Source: Sound Digest Archive v01.n119
Gang,
I got the ol' RCA circuit together. It really does sound
wonderful--except the EQ is noticably "off" under about 70hz.
Which capacitor do I "tweak" to increase LF response (or increase HF
cut)?? Do you increase or decrease the value?
Thanks for any help! -Chris
=========================================================================
From: RALPH POWER <POWER.RALPH@epamail.epa.gov>
Subject: RCA phono stage feedback problem
Date: Wed, 10 Sep 1997 15:59:07 -0400
Source: Sound Digest Archive v01.n018
Hi all,
When I let the input and output interconnects accidently cross behind my standalone
RCA phono stage with the cathode follower output, it starts to oscillate (?)
(beep-beep-beep).
When I separate the cables, the beeping stops and the preamp behaves normally.
As long as I keep the cables apart I have no problems. But if it indicates a circuit
problem, I want to address it.
Can you tell me what causes this ?
Does this indicate a problem in my circuit ?
What are suggested fixes ?
Thanks in advance for any comments and suggestions.
- Ralph
=========================================================================
From: Bob Danielak <rdaniela@ew.lmms.lmco.com>
Subject: Re: RCA phono stage feedback problem
Date: Wed, 10 Sep 1997 17:12:44 -0400
Source: Sound Digest Archive v01.n019
RALPH POWER wrote:
>
> Hi all,
>
> When I let the input and output interconnects accidently cross behind my standalone
> RCA phono stage with the cathode follower output, it starts to oscillate (?)
> (beep-beep-beep).
>
> When I separate the cables, the beeping stops and the preamp behaves normally.
> As long as I keep the cables apart I have no problems. But if it indicates a circuit
> problem, I want to address it.
>
> Can you tell me what causes this ?
> Does this indicate a problem in my circuit ?
> What are suggested fixes ?
>
> Thanks in advance for any comments and suggestions.
>
> - Ralph
this is not uncommon for high gain stages.
what you have is
electromagnetic coupling from output back to input = positive feedback!
this causes the oscillations. there is nothing necessarily wrong with
your circuit. just probably ought to shield those interconnects.
at least the inputs.
i'd imagine that if they are picking up their own stray fields
they're bound to be picking up other crap, too.
have you had any noise problems?
either shield those lines or keep them away from each other
(and from stray fields : eg ac power lines, etc)
hth
bob.d.
=========================================================================
From: SHAMSUL Bahrin Kamarudin <shamsul.BK@innosabah.com.my>
Subject: RCA Radiotron Des. HB CD version ?
Date: Mon, 20 Jul 1998 12:11:30 +0800
Source: Sound Digest Archive v01.n349
Greetings.
Just would like to know if anyone knows where I can get a CD version of the
RCA Radiotron Designers Handbook ?
I recall someone selling it on the web but I have lost the website address ?
Regards.
::-)
\\\///
/ _ _ \
(| (.)(.) |)
|--------.OOOo--()--oOOO.----------------------------------------|
mailto:shamsul.BK@innosabah.com.my
mailto:0198107360@sms.celcom.com.my
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
_/ H/P: 019-8107360 TEL: 6088-244185 FAX: 6088-251679 _/
_/ http://www.innosabah.com.my _/
_/ ======================================================== _/
_/ TO BECOME A LEADING HI-TECH, PEOPLE ORIENTED FINANCIAL _/
_/ SERVICES COMPANY WHICH OFFERS WORLD CLASS _/
_/ INNOVATIVE PRODUCTS AND SERVICES _/
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
_/ THIS IS A | INNOSABAH SECURITIES SDN BHD (194990-K) _/
_/ COMPUTER GENERATED | 11 EQUITY HOUSE, BLOCK K, _/
_/ ELECTRONIC MAIL | SADONG JAYA, KARAMUNSING, _/
_/ AND IS DEEMED TO | 88100 KOTA KINABALU, SABAH, _/
_/ HAVE BEEN SIGNED | M A L A Y S I A _/
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
=========================================================================
From: "Johari Yip" <hfyip@pacific.net.sg>
Subject: Re: RCA Radiotron Des. HB CD version ?
Date: Mon, 20 Jul 1998 13:33:18 +0800
Source: Sound Digest Archive v01.n349
I think Antique Electronics sells they at $29.90 the last time I saw it.
Johari
- ----------
> From: SHAMSUL Bahrin Kamarudin <shamsul.BK@innosabah.com.my>
> To: 'JOE-NET Mailist' <sound@deliverator.io.com>
> Subject: RCA Radiotron Des. HB CD version ?
> Date: Monday, July 20, 1998 12:11 PM
>
> Greetings.
>
> Just would like to know if anyone knows where I can get a CD version of
the
> RCA Radiotron Designers Handbook ?
>
> I recall someone selling it on the web but I have lost the website
address ?
>
>
> Regards.
>
> ::-)
>
>
>
> \\\///
> / _ _ \
> (| (.)(.) |)
> |--------.OOOo--()--oOOO.----------------------------------------|
> mailto:shamsul.BK@innosabah.com.my
> mailto:0198107360@sms.celcom.com.my
> _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
> _/ H/P: 019-8107360 TEL: 6088-244185 FAX: 6088-251679 _/
> _/ http://www.innosabah.com.my _/
> _/ ======================================================== _/
> _/ TO BECOME A LEADING HI-TECH, PEOPLE ORIENTED FINANCIAL _/
> _/ SERVICES COMPANY WHICH OFFERS WORLD CLASS _/
> _/ INNOVATIVE PRODUCTS AND SERVICES _/
> _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
> _/ THIS IS A | INNOSABAH SECURITIES SDN BHD (194990-K) _/
> _/ COMPUTER GENERATED | 11 EQUITY HOUSE, BLOCK K, _/
> _/ ELECTRONIC MAIL | SADONG JAYA, KARAMUNSING, _/
> _/ AND IS DEEMED TO | 88100 KOTA KINABALU, SABAH, _/
> _/ HAVE BEEN SIGNED | M A L A Y S I A _/
> _/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
>
=========================================================================
From: Ed_Fausto@colpal.com (Ed Fausto)
Subject: Re: RCA Radiotron Des. HB CD version ?
Date: Mon, 20 Jul 1998 14:53:43 -0400
Source: Sound Digest Archive v01.n350
Old Colony offers the CD ROM but I can't remember how much. If you
can afford the book, it is available at Angela Instruments from $100
to $150 depending on the condition.
Ed
______________________________ Reply Separator _________________________________
Subject: RCA Radiotron Des. HB CD version ?
Author: SHAMSUL Bahrin Kamarudin <shamsul.BK@innosabah.com.my> at INTERNET
Date: 7/20/98 12:11 PM
Greetings.
Just would like to know if anyone knows where I can get a CD version of the
RCA Radiotron Designers Handbook ?
I recall someone selling it on the web but I have lost the website address ?
Regards.
::-)
\\\///
/ _ _ \
(| (.)(.) |)
|--------.OOOo--()--oOOO.----------------------------------------|
mailto:shamsul.BK@innosabah.com.my
mailto:0198107360@sms.celcom.com.my
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
_/ H/P: 019-8107360 TEL: 6088-244185 FAX: 6088-251679 _/
_/ http://www.innosabah.com.my _/
_/ ======================================================== _/
_/ TO BECOME A LEADING HI-TECH, PEOPLE ORIENTED FINANCIAL _/
_/ SERVICES COMPANY WHICH OFFERS WORLD CLASS _/
_/ INNOVATIVE PRODUCTS AND SERVICES _/
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
_/ THIS IS A | INNOSABAH SECURITIES SDN BHD (194990-K) _/
_/ COMPUTER GENERATED | 11 EQUITY HOUSE, BLOCK K, _/
_/ ELECTRONIC MAIL | SADONG JAYA, KARAMUNSING, _/
_/ AND IS DEEMED TO | 88100 KOTA KINABALU, SABAH, _/
_/ HAVE BEEN SIGNED | M A L A Y S I A _/
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
=========================================================================
From: SHAMSUL Bahrin Kamarudin <shamsul.BK@innosabah.com.my>
Subject: Ref:>Re: RCA Radiotron Des. HB CD version ?
Date: Tue, 21 Jul 1998 09:42:58 +0800
Source: Sound Digest Archive v01.n350
*** Ed Fausto on 20/07/1998 around 2:53 PM -0400 wrote ..........
- -> Old Colony offers the CD ROM but I can't remember how much. If you
- -> can afford the book, it is available at Angela Instruments from $100
- -> to $150 depending on the condition.
- ->
- -> Ed
- ->
Cool.
Thanks for the INFO.
Regards.
::-)
\\\///
/ _ _ \
(| (.)(.) |)
|--------.OOOo--()--oOOO.----------------------------------------|
mailto:shamsul.BK@innosabah.com.my
mailto:0198107360@sms.celcom.com.my
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
_/ H/P: 019-8107360 TEL: 6088-244185 FAX: 6088-251679 _/
_/ http://www.innosabah.com.my _/
_/ ======================================================== _/
_/ TO BECOME A LEADING HI-TECH, PEOPLE ORIENTED FINANCIAL _/
_/ SERVICES COMPANY WHICH OFFERS WORLD CLASS _/
_/ INNOVATIVE PRODUCTS AND SERVICES _/
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
_/ THIS IS A | INNOSABAH SECURITIES SDN BHD (194990-K) _/
_/ COMPUTER GENERATED | 11 EQUITY HOUSE, BLOCK K, _/
_/ ELECTRONIC MAIL | SADONG JAYA, KARAMUNSING, _/
_/ AND IS DEEMED TO | 88100 KOTA KINABALU, SABAH, _/
_/ HAVE BEEN SIGNED | M A L A Y S I A _/
_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/_/
=========================================================================
From: pitaro@ozemail.com.au
Subject: RCA RIAA - not minivans :-)
Date: Thu, 30 Jul 1998 18:11:39 EST
Source: Sound Digest Archive v01.n367
Hi all,
Well several weeks ago I finally got by 417A line amp using line level
transformers, up and working without any hum. It's been a great learning
experience!!! After tyring DC heaters (now I've found out for myself that
I too like AC heaters), every combination of earthing possible etc.....It
turns out that there just wasn't enough filter in the power B+ supply
which caused the hum. I've been playing with different components to tune
the preamp to my system and taste. I really like the paper and oil
capacitors in the power supply. Now that I'm happy with it, I have to say
that it really is the best line stage I've heard and I'm trying not to be
biased.
Now I want to get an RIAA circuit going. I'd love to be able to do it
passively using chokes like Tom but my knowledge is too limited at the
moment. So I've decided to build a simpler circuit. I've got all the
parts necessary to build the RCA RIAA circuit but I wanted to use the 6SL7
rather than the 12AX. My question relates to the eq'ing of the different
tubes.
I know that there is slightly less gain using the 6SL7 but I've got some
pretty good input/mic trannies with heaps of gain (about 44) to combat
this. However the plate resistance etc is different and I was wondering
what effect this would have on the RIAA? Can I build the circuit with the
octal tube and still have a reasonable approximation for the RIAA eq?
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: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: RE: RCA RIAA - not minivans :-)
Date: Thu, 30 Jul 1998 13:24:24 -0400
Source: Sound Digest Archive v01.n368
hello harry!
sorry about the mini-van thread.
seems that was all that anyone got out of my post.
i guess nobody cares about the other topics that i really wanted
to relate: 1626 & 300B SE amps, combined
choke+resistor plate loads... etc ;)
so to make up for the off-topic....
i have done quite a bit of analysis on the old RCA RIAA circuit.
as it turns out, the 6sl7 actually works better (in terms of matching
the RIAA eq,) than the 12ax7/7025.
plug-and-play. it works!
you won't really lose that much gain.
bob.d.
> ----------
> From: pitaro@ozemail.com.au[SMTP:pitaro@ozemail.com.au]
> Reply To: pitaro@ozemail.com.au
> Sent: Thursday, July 30, 1998 7:11 PM
> To: sound@deliverator.io.com
> Subject: RCA RIAA - not minivans :-)
>
> Hi all,
>
> Well several weeks ago I finally got by 417A line amp using line level
> transformers, up and working without any hum. It's been a great learning
> experience!!! After tyring DC heaters (now I've found out for myself that
> I too like AC heaters), every combination of earthing possible etc.....It
> turns out that there just wasn't enough filter in the power B+ supply
> which caused the hum. I've been playing with different components to tune
> the preamp to my system and taste. I really like the paper and oil
> capacitors in the power supply. Now that I'm happy with it, I have to say
> that it really is the best line stage I've heard and I'm trying not to be
> biased.
>
> Now I want to get an RIAA circuit going. I'd love to be able to do it
> passively using chokes like Tom but my knowledge is too limited at the
> moment. So I've decided to build a simpler circuit. I've got all the
> parts necessary to build the RCA RIAA circuit but I wanted to use the 6SL7
>
> rather than the 12AX. My question relates to the eq'ing of the different
> tubes.
>
> I know that there is slightly less gain using the 6SL7 but I've got some
> pretty good input/mic trannies with heaps of gain (about 44) to combat
> this. However the plate resistance etc is different and I was wondering
> what effect this would have on the RIAA? Can I build the circuit with the
> octal tube and still have a reasonable approximation for the RIAA eq?
>
>
>
> 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: pitaro@ozemail.com.au
Subject: RE: RCA RIAA - not minivans :-)
Date: Fri, 31 Jul 1998 12:27:39 EST
Source: Sound Digest Archive v01.n369
** Reply to note from "Danielak, Robert M" <robert.m.danielak@lmco.com> Thu, 30 Jul 1998 13:24:24 -0
400
>
> hello harry!
>
> sorry about the mini-van thread.
Hey, don't worry about it. It doesn't bother me. I like cars. Still
race them occasionally. By the way, I'm probably one of the biggest
offenders of off topic discussions anyway.
> seems that was all that anyone got out of my post.
>
> i guess nobody cares about the other topics that i really wanted
> to relate: 1626 & 300B SE amps, combined
> choke+resistor plate loads... etc ;)
>
> so to make up for the off-topic....
>
> i have done quite a bit of analysis on the old RCA RIAA circuit.
> as it turns out, the 6sl7 actually works better (in terms of matching
> the RIAA eq,) than the 12ax7/7025.
> plug-and-play. it works!
>
> you won't really lose that much gain.
>
Thanks heaps.
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: Steve Van Osdell <svanos@toast.net>
Subject: RCA transription turntable
Date: Sun, 08 Feb 1998 23:10:44 -0600
Source: Sound Digest Archive v01.n186
There is an RCA Radio Station Transcription turntable that comes mounted on
top of a gunmetal gray cabinet for auction on ebay. It closes tonight at
22:30 Pacific time, and the current bid is only $100. Comes with original
arm and cartridge. I'd bid on it if I knew something more about it.
Thought some of you out there might.
Steve
=========================================================================
From: el34@juno.com
Subject: Re: RCA transription turntable
Date: Mon, 9 Feb 1998 10:30:34 -0500
Source: Sound Digest Archive v01.n187
On Sun, 08 Feb 1998 23:10:44 -0600 Steve Van Osdell <svanos@toast.net>
writes:
>There is an RCA Radio Station Transcription turntable that comes
>mounted on top of a gunmetal gray cabinet for auction on ebay.
I'm not sure it would be something you would want in your house. They
weigh a ton, and are built like a Maytag washing machine. I'm not
kidding, they have a huge "washing machine" motor mounted in the bottom
of the cabinet coupled by a big steel shaft to the platter. I have seen a
250 pound DJ stand on the platter and spin around on it. It was a real
hoot, and did no damage at all.
If it has the original arm they were huge clunky affairs, I can't imagine
mounting a modern cartridge to one of these beasts. They were designed
for cartridges that tracked in ounces instead of grams.
_____________________________________________________________________
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
Or call Juno at (800) 654-JUNO [654-5866]
=========================================================================
From: Jeff Mai <jmai@fn.net>
Subject: RCA woofer info wanted
Date: Wed, 7 Jan 1998 01:11:08 -0600
Source: Sound Digest Archive v01.n154
Has anyone out there in Joe-land heard of RCA 15 inch woofers, model
numbers 103LX and P-52LX?
Seem to be original equipment for my RCA theatre horns. I'd like to get
some data on them so I can look for suitable substitutes. (Unless
someone's got 4 of them laying around in their garage, Ed?)
Jeff
jmai@fn.net
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: RCA Woofers
Date: Fri, 06 Feb 1998 21:05:06 -0800
Source: Sound Digest Archive v01.n185
I seem to recall someone here looking for RCA Woofers recently. Kent
Elliot has a pair of 9449s for $400.
KentElltt <kentelltt@aol.com>
Dan Marshall
=========================================================================
From: Steve Van Osdell <svanos@toast.net>
Subject: RCA 'Worlds Fair' Horns
Date: Wed, 04 Mar 1998 20:16:13 -0600
Source: Sound Digest Archive v01.n208
Does anybody know what these are worth minus drivers (bare horns) in
perfect condition. I've located some! Believe it or not.
Thanks, Steve
=========================================================================
From: Joseph Lowe <jlowe@cdc.net>
Subject: Re: RCA 'Worlds Fair' Horns
Date: Thu, 5 Mar 1998 09:24:31 -0500 (EST)
Source: Sound Digest Archive v01.n208
On Wed, 4 Mar 1998, Steve Van Osdell wrote:
> Does anybody know what these are worth minus drivers (bare horns) in
> perfect condition. I've located some! Believe it or not.
>
> Thanks, Steve
>
Steve, you are the undisputed king of the dumpster divers! Where do you
put all the stuff you find???
=========================================================================
From: Eric Weitzman <eweitzman@acm.org>
Subject: RC filter for a power supply?
Date: Mon, 16 Nov 1998 23:02:53 -0800
Source: Sound Digest Archive v01.n494
I've got 5v of ripple on a 330v LC-filtered PS using a 2.5H input
choke. Since this is a PP amp, I can probably get away with
the ripple cancellation, except in the input/phase splitter.
I've read (in the RDH and an ARRL manual) that a simple RC
filter can be used to take care of the ripple in low power
consuming input stages. Seems peachy, I don't have to shell
out a hundred or two hundred bucks to build a pair of
10H-based LCLC filters.
The catch is, I don't have the slightest idea how to design
this particular filter. I'm not even sure if I know what
they're talking about. I _assume_ they're talking about a
notch filter at 60 or 120hz that's in series with the PS. If
so, how does one pick values, power ratings, and types for
the R and C? If not, does anyone have any pointers to a
reference for me?
- - Eric
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: RC filter for a power supply?
Date: Thu, 19 Nov 1998 19:43:23 +0100
Source: Sound Digest Archive v01.n496
>The catch is, I don't have the slightest idea how to design
>this particular filter. I'm not even sure if I know what
>they're talking about. I _assume_ they're talking about a
>notch filter at 60 or 120hz that's in series with the PS.
It is not a notch, it is a lowass (cuts high, but high is relatively low
here, given the fact that you want to supress 120 Hz). Often used is 10 Hz
or ower
Th C value id defined by the impedance of the load, example:
a single triode stage with 47 k-ohm in the anode at least shows 47 k. In
practice Rp (of tube) adds another say 8 k (ECC82/12 AU7) and if the
cathode is not bypassed Rp becomes more (8 k + (mu +1)xRcathode)
Assume it is 47 k-ohm. Now you want a certain low frequency cut-off. If you
use 10 uF the cutoff becomes:
1/(2xpixRxC) = 0,33 Hz which is reaonably low...
Now the series resistor in the filter may have the same value, that gives
again 0,33 Hz, but, the dc current (assume 3 mA for the given tube) will
give a drop of 47x3 = 144 V !
A smaller value of 4,7 k will give 3,3 Hz and a drop of 14 V. Acceptable ?
The damping at becomes roughly the ratio of 4,7k to the impedance of 10 uF
at 120 Hz (1/(2xpix120)). It finally gives 4,7 k versus 132 ohm = 35 times
(also equal to 120 Hz divided by 3,3 Hz)
If 35 times is enough depends on the whole circuit, but you may repeat such
an RC filter giving you in theory 35 times 35 rejection (1225)
More than 20 uF at once will give you
Succes
Guido
>If
>so, how does one pick values, power ratings, and types for
>the R and C? If not, does anyone have any pointers to a
>reference for me?
>
>- Eric
>
><a lost soul who never took EE101>
>
>
=========================================================================
From: Christian Rintelen <rintelen@datacomm.ch>
Subject: Re: RC filter for a power supply?
Date: Fri, 20 Nov 1998 12:04:31 +0100
Source: Sound Digest Archive v01.n497
evaguido wrote:
> It is not a notch, it is a lowass (cuts high, but high is relatively low
> here, given the fact that you want to supress 120 Hz)
Lowass... Hmm. A new bike from Harley, a beefed up version of the Lowrider??
(Kinda liked that typo!)
Christian B^)
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: RC filter for a power supply?
Date: Fri, 20 Nov 1998 20:54:12 +0100
Source: Sound Digest Archive v01.n497
At 12:04 20-11-98 +0100, Christian Rintelen wrote:
>
>
>evaguido wrote:
>
>> It is not a notch, it is a lowass (cuts high, but high is relatively low
>> here, given the fact that you want to supress 120 Hz)
>
>Lowass... Hmm. A new bike from Harley, a beefed up version of the Lowrider??
>(Kinda liked that typo!)
Shouldn't be a highass or :-)
Guido
>Christian B^)
>
>
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: RDH and choke-loading
Date: Mon, 27 Oct 1997 10:15:57 -0600
Source: Sound Digest Archive v01.n090
Looking at my little RDH 3, I notice the sample schematics for
choke-loading a triode plate include a cap and resistor (marked R sub L)
going from plate to ground, between the plate and the choke. Is this a way
of representing the following grid resistor, or something else? Are they
suggesting that one load the tube in addition to using a choke?
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: Ron Bales <rbales@mail.gte.net>
Subject: Re: RDH and choke-loading
Date: Mon, 27 Oct 1997 12:50:58 -0500
Source: Sound Digest Archive v01.n090
Grover Gardner wrote:
>
> Looking at my little RDH 3, I notice the sample schematics for
> choke-loading a triode plate include a cap and resistor (marked R sub L)
> going from plate to ground, between the plate and the choke. Is this a way
> of representing the following grid resistor, or something else? Are they
> suggesting that one load the tube in addition to using a choke?
Hi Grove, RsubL is the load to be driven. Haven't seen the particular
drawing but that is the standard nomenclature. The cap in this case is
the coupling cap which keeps the B+ voltage off the load, as you guessed
often the grid R (or RsubG) of the next stage. The coupling cap and RL
do form part of the AC load that the tube sees. The impedence of this
load is in parallel with the impedence of the loading choke.
Hope this helps
ROn
=========================================================================
From: Ron Bales <rbales@mail.gte.net>
Subject: Re: RDH and choke-loading
Date: Mon, 27 Oct 1997 12:50:58 -0500
Source: Sound Digest Archive v01.n091
Grover Gardner wrote:
>
> Looking at my little RDH 3, I notice the sample schematics for
> choke-loading a triode plate include a cap and resistor (marked R sub L)
> going from plate to ground, between the plate and the choke. Is this a way
> of representing the following grid resistor, or something else? Are they
> suggesting that one load the tube in addition to using a choke?
Hi Grove, RsubL is the load to be driven. Haven't seen the particular
drawing but that is the standard nomenclature. The cap in this case is
the coupling cap which keeps the B+ voltage off the load, as you guessed
often the grid R (or RsubG) of the next stage. The coupling cap and RL
do form part of the AC load that the tube sees. The impedence of this
load is in parallel with the impedence of the loading choke.
Hope this helps
ROn
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: Re: RDH and choke-loading
Date: Mon, 27 Oct 1997 21:21:17 -0600
Source: Sound Digest Archive v01.n091
At 12:50 PM -0500 10/27/97, Ron Bales wrote:
>Grover Gardner wrote:
>>
>> Looking at my little RDH 3, I notice the sample schematics for
>> choke-loading a triode plate include a cap and resistor (marked R sub L)
>> going from plate to ground, between the plate and the choke. Is this a way
>> of representing the following grid resistor, or something else? Are they
>> suggesting that one load the tube in addition to using a choke?
>
>
>Hi Grove, RsubL is the load to be driven. Haven't seen the particular
>drawing but that is the standard nomenclature. The cap in this case is
>the coupling cap which keeps the B+ voltage off the load, as you guessed
>often the grid R (or RsubG) of the next stage. The coupling cap and RL
>do form part of the AC load that the tube sees. The impedence of this
>load is in parallel with the impedence of the loading choke.
>
>Hope this helps
>
>ROn
I think that's it. Thanks, Ron.
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: Tim Reese <reese@nmr.MGH.harvard.EDU>
Subject: Re: RDH on CD rom
Date: Thu, 12 Mar 1998 12:28:12 -0500 (EST)
Source: Sound Digest Archive v01.n215
>As Thomas Danley writes:
>>
>> Hugh Dean wrote:
>>
>> Also, you might want to get a copy of "Radiotron Designers Handbook"
>> (which I understand is available on CD-Rom now), as well as lots of good
>> tube design info, it has a nice section on transformer theory and
>> design.
>
>Anybody know where this can be purchased? How much?
Try Old COlony Sound Labs in NH - 603-924-6371, fax 603-924-9467
audiotech@top.monad.tech
cheers tr
- ---------------------------------------------------------------
Tim Reese, MGH NMR Center reese@nmr.MGH.harvard.edu
=========================================================================
From: Rick Francis <rfranci@uoft03.UTOLEDO.EDU>
Subject: Re: RDH on CD rom
Date: Thu, 12 Mar 1998 13:28:33 -0500 (EST)
Source: Sound Digest Archive v01.n215
On Thu, 12 Mar 1998, Tim Reese wrote:
> >As Thomas Danley writes:
> >
> >Anybody know where this can be purchased? How much?
>
> Try Old COlony Sound Labs in NH - 603-924-6371, fax 603-924-9467
> audiotech@top.monad.tech
>
I bought one when Audio Advisor ran a special on them (CD-ROM version).
The pages are scanned and converted to PDF. Looks blurry on the screen,
prints out okay. For $30 the CD is okay, but... hard copy is better. I
think there is a hard copy on e-bay.
Rick
=========================================================================
From: "Lohse, Guenther VIM37" <Lohse.Guenther@dornier.dasa.de>
Subject: RE: Reactance annulling
Date: Wed, 01 Oct 97 08:53:00 PDT
Source: Sound Digest Archive v01.n050
Hi Marc, Ken
Reactance annulling is a process of cancelation different Reactance
directions, like a inductor with positive going reactance and a capacitor
with negative going reactance. (Sorry for the poor words I use here, because
english is a foreign language).
For more details refer to LCR resonant circuits. There below and above the
resonant frequency the impedance is greater than the R value (with phase
shift), at resonance the impedance is R value (without phase shift).
Also, if you want acoustic power from a speaker, then there is only the
resitive part of the acoustic impedance of the speaker relevant. Above its
resonant frequency the impedance has a great resistive part, below the
resonant frequency the reactance part dominate and the resistive part
decrease (acoustic impedance) .
Therefore below the resonant frequency the acoustic power also decrease.
With a horn you can extent the acoustic power below the resonace frequency,
because the acoustic reactance of the horn is of different direction and
cancels the reactance of the speaker.
If you use a speaker with a resonant frequency below that of the horn
cutoff, then you can load the horn near to cutoff frequency.
The problem is that you have no damping below the horn cutoff frequency
(backloaded horn) and so the resonance frequency of the speaker was not
damped, with result in pure higher frequency performance from overall
distortion due to velocity of the diaphragm.
Conclusion:
The reactance annulling is a principle to extent the low frequency output
of a driver with high resonant frequency.
G}nther
=========================================================================
From: darmah@goodnet.com
Subject: Reactance annulling...my take.
Date: Tue, 30 Sep 1997 22:09:14 +0000
Source: Sound Digest Archive v01.n050
Hi Joeneters:
First of all congrats Ken on really getting into the whole horn bit.
Your not as far off base as you may think.
Now I'll give my take on that scary term reactance annulling.
Sorry folks no math...just a description of what occurs when properly
done. Which will also show to some degree why, as Ken pointed out,
reactance annuling is in fact some what cut and try.
The following is very very generalized and full of gaping holes of
course. And as always I welcome input if you think I messed up.
And... I know I'll be opening a can of worms.
I was planning on putting much of this on my Lowther Web Site. But as
it seems now, Hell will freeze over twice before I ever get that
done.
Here's the basic bottom line: Reactance annulling is the process of
modifying a drivers suspension compliance in such a way so as to
provide maximum output at the horns cut off frequency. Sounds simple.
In some ways it is, in others it's not.
One thing not mentioned to often any more is that horn drivers with
resonance frequencies above the Fc of the horn are in fact desirable.
Especially for back loaded horns. Older literature points this out
more often. More later.
Front loaded horns:
Here we'll start with a horn of given dimensions with an Fc given
based on those dimensions. Reactance annulling itself will not lower
the effective Fc of the horn but does allow maximum output at Fc. Or
to put it another way. If the horn has an effective cut off frequency
( Fc) of 80 Hz based on it's mouth size, length and placement,
reactance anulling will not lower this to 40 Hz ( wouldn't that be
nice ) but does allow the horn to produce maximum sound pressure
levels all the way down to 80Hz. With out proper reactance annulling
response would generally start to fall at say 100 Hz or so.
Now we'll a take driver with nice beefey magnet ( low Qts ) and
attach it to the proper placement of the horns throat i.e the optimum
area. I know this would require some explaining but I assume you horn
fans know what I mean. Let's also assume this driver has a free air
resonance of say 110 Hz. Quite a bit obove that of the horns Fc.
The first thing that happens, and this is the beauty of horns, is
that the drivers free air resonace is completely supressed by the
very high impedance presented to it by the horns throat. This of
course extends the drivers response beyond what would normaly be
possible in most other loads and provides some killer damping.
As stated earlier the horns response will start to drop some what
above it's actual Fc. This is common knowledge found in any speaker
book dealing with the subject. It's that "choking " Bruce Edgar
describes.
I've peronally come to conclusion that close to Fc most horn types
stop "transforming pressure" and "revert" more to quarter wave
resonators until they finally give up completely. Which is also the
reason that the effective length of the horn is a major contributor
to it's Fc. I think I may be alone with this opinion and so the worms
wake up.
So now we'll ad a sealed box to the rear of our driver. Basically
changing the drivers suspension parameters. This of course raises
the resonace frequency of the driver again and of course the Q of
that resonance. And we now all start seeing where this is going.
When everything is taken into acount, we have a horn throat with an
impedance that supresses the free air resonance of the driver
extending it's response. At the same time we have a volume of air
behind the driver which raises the resonance frequency and the Q of
that resonance in just the correct way so as to compensate for the
horns falling response just above Fc. The drivers resonance now
moves to a point somewhere below Fc of the horn with a little "Q
hump" for added out put at Fc.
So even with out a lot of math we could start with a large rear
chamber and manipulate the volume intil things work. Acoustic and
voice coil impedance measuremets would be in order here.
It really is that simple. It's the math that's tough.
The volume of air behind the driver has the benefit of keeping cone
excursions very low below Fc of the horn. It should also be easily
seen how various drivers can to some extent be matched to the horn
simply by adjusting the back volume. At least for low end response.
The upper limit depends on the magnets power and cone mass.
Front loaded horns:
Let's assume the same driver and horn as above. Is reactance
annulling possible at all any more?
Well yes but only through the manipulation of the drivers suspension
compliance directly. By the-hap hazard example given above it should
be at least somewhat evident that if we could give the driver just
the right amount "stiffness" in it's suspension, or "softness
depending on what driver we stat with, we could achieve the same
results. Including to some degree the rapid roll off and reduced cone
movement!!! Wow.
The problem is of course that unless your willing to experiment,
probably endlessly, with materials that could stiffen the suspension
of a given driver, you can just about forget it. This is the reason
there are so many reasonably well working front loaded horn designs
and not that many rear loaded ones.
One of the key choices in designing a rear loaded horn with proper
reactance annulling is choosing at what point along the horns throat
i.e area to attach the driver. The driver having given parameters
that we can't change as in the front loaded horn, must be attached at
the throat position exactly where optimum compensation as described
earlier can take place.
Am I making any sense here? I almost feel like I'm sounding like a
"bottle rocket scientist" If ya know what I mean.
I have a mathematical description of exactly how a rear loded horn
has to be designed some where in my pile of papers.
But if I recall correctly it starts with a given horn, making a point
of establishing the actual horns Fc and then changing the drivers
suspension compliance. But I guess one could work backwards...or
maybe sideways?
The bottom line is though that the process is very difficult,
it requires exact knowledge of the drivers and the horns parameters
and is always only correct for the specific driver chosen. Never for
any other driver.
And so know the worms have started to crawl.
Lowther fans that are still reading will be asking: " hey what if my
PM 6 had a resonance frequency of 80 Hz or so. I'd probably get
better response down to 70 Hz or so than I do now from my Fidelio (
or whatever other way to small Lowther horn) if what that dude say's
is correct."
Indeed I believe this would be the case in many applications. Most
small Lowther designs, for reasons I won't get into here take a dive
at about 80 Hz. The drivers resonance frequencies however are usually
any where from a low of 35 Hz to 50 Hz. No hope for much of the
effect described above.
I too have longed for a PM 2 A and 6 C with Fres of 80 Hz or so for
my Academy's. But Lowthers need a soft suspension around the
perimiter of the main cone. Any stiffening would have to be done at
the spider only.
Lowther's did have very high Fres's at some time during the mid
1980's due to a very stiff outer and inner suspension. But because of
this ( and a few other reasons ) didn't sound all to good.
Are there other solutions to the "reactance annulling with back
loaded horns problem? Well maybe. And now the worms start to multiply
like rabbits.
Ever heard of "actively equalized 6th order reflex alignments" Sure
you have.
And why not with horn drivers? Design a circuit that would give us an
adjustable Q of the driver at a, lets call it "virtuall resonance
frequency" all between the pre amp and power amp and see what we can
come up with.
Of course we'd do it all with tubes.
Back loaded horns are open, I mean open as in no load below Fc. For
a lowther that means plenty of cone movement, completely undamped
below the horns cutoff.
I'll tell you from peronal exerience that if you like rock and roll,
90 dB + , most Lowther's in Lowther style horns sound better when
some attempt at bandwidth limiting is made below 80 Hz or whatever
your room supports. Don't feed em what they can't swallow.
Reactance annuling aside for a moment the low end response of a bass
horn is dictated more by it's own size and geometry than by the
driver used. I've proven this to myself.
Reactance annuling itself can't work any magic. It can only be used
to optimize what is there already.
Now Ken I know you wanted math. Sorry I don't have any.
But I figured the above might give better insight into what occurs
during reactance annulling. Or maybe just a different slant.
And in reading the above myself I see that I haven't really offered
any solutions the the questions you asked.
But I'll send it out any way. Maybe some one else on the list has
some advice.
Oh well... more privatly.
Best Regards
Marc S. Wauters
darmah@goodnet.com
Internet Paging: "http://wwp.mirabilis.com/544722"
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From: "P.A. & M. Almeflo" <sd@ljusdal.se>
Subject: Reactance anulling for tractrix horns
Date: Sun, 18 Jan 1998 13:25:09 +0100
Source: Sound Digest Archive v01.n164
Hi all,
Has anyone got any info or formulas for reactance anulling of tractrix
horns?
Best regards,
Per Arne Almeflo
=========================================================================
From: Thomas Danley <tom@ppci.com>
Subject: Re: Reactance anulling for tractrix horns
Date: Mon, 19 Jan 1998 20:26:03 -0600
Source: Sound Digest Archive v01.n164
P.A. & M. Almeflo wrote:
>
> Hi all,
> Has anyone got any info or formulas for reactance anulling of tractrix
> horns?
> Best regards,
> Per Arne Almeflo
Hi
Reactance anulling in a horn is a way of increasing the output as one
aproaches the low frequency cutoff of the horn. It involves slowing down
the rate of expansion at the throat end of the horn so that the horn is
smaller in diameter for a longer distance. The math that defines how
much of this effect is optimum includes the driver perameters as well as
the horn low cutoff etc. and is expressed as "M" ot "T" for its
hyperbolic component. In other words, applying this technique to the
Tractrix flare, makes it something other than a Tractrix flare
For low frequencies, efficient cone driven horns * are fairly narrow
band devices so the dispersion properties of the tractrix flare are
probably out weighed by the need to have the lows cutoff possible given
the size of the horn and that means a hyperbolic flare.
(* horns are also sometimes used to confine the directivity, increasing
the on axis SPL without a significant increase in actual efficiency)
Hyperbolic flares are thought by some to have distortion problems which
under some conditions, they are higher than other types.
At low frequencies however, the bandwidth and power density are low
enough so the distortion is insignificant. One of the best papers of all
time for designing efficient low frequency horns in in the AES
loudspeaker anthology (the 2nd) by Marshal Leach, I have built dozens of
LF and Mid horns based on his math and foun