Sound Practices Mailing List Files - Volume 1
=========================================================================
From: Patrick Currie <tubesguy@execpc.com>
Subject: Ubangi?
Date: Tue, 14 Oct 1997 19:46:01 -0500
Source: Sound Digest Archive v01.n069
I've been away for a couple of days, and my mail filtering system may have
filtered away the definitive answer, but there was an African tribe that
went to extreme and, depending on one's perspective, grotesque measures in
stretching out there lower lips by punching a hole in the lip and then
inserting progressively larger flat wooden discs in the hole. The results
ultimately were hugely stretched lips with impressively large wooden discs
inserted. So: a) these may have been the Ubangis, and, b) this would
account for someone naming a large horn system, perhaps politically
incorrectly, after the tribe.
As always, happy to show off my impressive store of African knowledge, I
remain - Pat
Pat Currie (tubesguy@execpc.com)
(608)233-8956, 266-9290 (Madison, WI)
=========================================================================
From: Andre Jute <andre@indigo.ie>
Subject: ***Ubangie and more risotto recipes--definitely off-topic
Date: Tue, 14 Oct 1997 20:58:42 +0100 (BST)
Source: Sound Digest Archive v01.n068
At 9:32 am -0400 14/10/97, RALPH POWER wrote:
>Hi Bill,
>
>You said:
>
>>I have to ask about the origin and meaning of the word 'Ubangie'.
>
>I have always thought that the "Ubangie" was a tribe of natives in Africa.
>
>Maybe Andre can speak about this.....
>
> - Ralph
Oubangui, a tribe who live on the Bangui in Zaire. Nothing special about
them; they don't like anyone else, but that is a common attitude in Africa.
When I was in the Congo in the liberation, theirs was thought too dangerous
a region to fight a war in, so I didn't get up there the first time round.
Later I hunted crocodile up the Bangui with my brother; the London
Telegraph said, in a review of my book based on the experience, that it is
an area where one does not go except in armoured column with air cover.
That's a very British understatement; I wish they had told me before I went.
'Ubangie', a mythical tribe of fabulous riches, sought by Dr Livingstone.
Said to live beyond the killer pigmy with their blowdarts (no antidote,
those hit by their arrows choke to death in 30 minutes), the ring of black
tree snake (no antidote; those bitten choke to death in 8 minutes), and the
cannibals (those captured cook or bake to death in four hours so that they
will be tender, except if they are to have their head chilled and their
brains eaten with a spoon in which case their end is mercifully shortened
to minutes, in fact only until the last of their brains are scooped out of
their heads--same principle as live monkey brains, considered a delicacy in
Hong Kong). Take your pick. I ate with more southernly cannibals once; I
took my own plate and cutlery and table linen since theirs (broad leaves
picked some time before) was none too clean. Never got to ask the northern
cannibals 'before the Ubangie' whether there were in fact Ubangie beyond
because my brother and his men would ripple in revulsion at the sight of
cannibals, shoot them, then ripple in revulsion some more at their narrow
escape from being invited to be dinner; they were very even-handed, not
racist at all: they would shoot pigmy on sight too, and black tree snakes,
and Ubangie if we ever saw any, though I am reasonably sure we didn't,
unless they were some odd-looking types we found in the stomachs of
crocodiles that looked like Tuareg slave traders to me, but then what do I
know, I was only there for a holiday. If one is curious, one has to be
quick in some parts of Africa, or the situation and the characters change
before one can ask any questions.
Never had any ambition to search too actively for mythical tribes; no need
really, as my people knew where to pick up diamonds in the desert, where
only the government and de Beers would be shooting at one, and our mom was
keen for us kids to eschew unnecessary risks.
Livingstone was still several hundred miles south and a thousand east of
where the Ubangie are supposed to live when Stanley caught up with him and
they went home and lived happily ever after. Up there those guys would
probably have been eaten, and history would be different. I've been quite a
few rough places in Asia, Africa and South America, but up on the Bangui,
visiting the home of the fabled Ubangie, probably takes the prize.
Andre
Been there. Done that. Smarter now. Make high-voltage tube amps.
Andre Jute
andre@indigo.ie
COMMUNICATION JUTE
- --we support pages for music lovers, writers and audiophiles at
http://www.foundmark.com/ComJute/ComJuteF1.html
=========================================================================
From: Joe Pledger <doodle@navicom.com>
Subject: Re: ***Ubangie and more risotto recipes--definitely off-topic
Date: Tue, 14 Oct 1997 18:51:32 -0700
Source: Sound Digest Archive v01.n069
Andre Jute wrote:
>
-snip-
> their heads--same principle as live monkey brains, considered a delicacy in
> Hong Kong).
-snip-
Andre, Don't forget Vietnam. I used to take lunch break across the
street (in Saigon) which had split tables with circles cut in the
centers to hold the monkey heads..! Guess they had stopped the practice
in consideration for the americans who couldn't eat their spring-rolls
while someone was screaming...!
-snip-
Then there was our Colonel who had someone capture the biggest goddamn
bat I've ever seen, and snipped it's head off, boiled it clean and
preserved it as a skull speciman (fangs and all). The resident janitor
was out of HIS skull hoping to be able to drink it's blood (so he could
service every hooker in town without getting tired) until the head was
cut off-then it became taboo! and he wouldn't touch it.
Then there's Bangkok, but if you don't believe in witchcraft...why
get into that.
Ralph, don't drift off topic like that again, unless you want the
details!
Joe Pledger
> Andre
> Been there. Done that. Smarter now. Make high-voltage tube amps.
>
> Andre Jute
> andre@indigo.ie
> COMMUNICATION JUTE
> --we support pages for music lovers, writers and audiophiles at
> http://www.foundmark.com/ComJute/ComJuteF1.html
=========================================================================
From: "SJ Creamer" <screamer@NirvanaAudio.com>
Subject: Re: ***Ubangie and "Seinfeld"--definitely off-topic
Date: Tue, 14 Oct 1997 18:05:32 -0500
Source: Sound Digest Archive v01.n069
On 14 Oct 97 at 20:58, Andre Jute wrote:
> >Maybe Andre can speak about this.....
> >
> > - Ralph
>
> Oubangui, a tribe who live on the Bangui in Zaire. Nothing special about
> them;<snip>
Great story Andre, really.
Funny thing, I think the writers of the US TV show Seinfeld, based their
character Peterman on your lifes adventures.
...screamer
www.NirvanaAudio.com
phn/fax 1 516 285 1950
screamer@NirvanaAudio.com
PO Box 1053 Valley Stream, NY 11582 USA
=========================================================================
From: Andre Jute <andre@indigo.ie>
Subject: Re: ***Ubangie and "Seinfeld"--definitely off-topic
Date: Wed, 15 Oct 1997 03:31:25 +0100 (BST)
Source: Sound Digest Archive v01.n069
At 6:05 pm -0500 14/10/97, SJ Creamer wrote:
>On 14 Oct 97 at 20:58, Andre Jute wrote:
>
>
>> >Maybe Andre can speak about this.....
>> >
>> > - Ralph
>>
>> Oubangui, a tribe who live on the Bangui in Zaire. Nothing special about
>> them;<snip>
>
>Great story Andre, really.
>
>Funny thing, I think the writers of the US TV show Seinfeld, based their
>character Peterman on your lifes adventures.
>
>
>...screamer
Take a trip Screamer. There are hungry cannibals a lot of places you might
like. Do your duty. Go feed them.
When-- er,-- if you make it back, I'll write a sitcom about you. Screamer
gets an Itch. Screamer lands in Africa. Screamer and the Crocodile.
Screamer inside the Crocodile. Screamer at the Pearly Gates. Screamer in
the Hot Place. Is that six episodes yet? Thank god there is no hook for a
follow-on six!
Andre
Andre Jute
andre@indigo.ie
COMMUNICATION JUTE
- --we support pages for music lovers, writers and audiophiles at
http://www.foundmark.com/ComJute/ComJuteF1.html
=========================================================================
From: Bob Chernofsky <bobc@mci2000.com>
Subject: Re: ***Ubangie and "Seinfeld"--definitely off-topic
Date: Wed, 15 Oct 1997 05:56:43 -0700
Source: Sound Digest Archive v01.n069
- -----Original Message-----
From: SJ Creamer <screamer@NirvanaAudio.com>
To: sound@deliverator.io.com <sound@deliverator.io.com>
Date: Tuesday, October 14, 1997 4:11 PM
Subject: Re: ***Ubangie and "Seinfeld"--definitely off-topic
On 14 Oct 97 at 20:58, Andre Jute wrote:
> >Maybe Andre can speak about this.....
> >
> > - Ralph
>
> Oubangui, a tribe who live on the Bangui in Zaire. Nothing special about
> them;<snip>
>Great story Andre, really.
>Funny thing, I think the writers of the US TV show >Seinfeld, based their
>character Peterman on your lifes adventures.
>...screamer
www.NirvanaAudio.com
> phn/fax 1 516 285 1950
> screamer@NirvanaAudio.com
> PO Box 1053 Valley Stream, NY 11582 USA
I think there is "MORE" of a chance that Peterman's are real!!! Where is
"Tattoo" when you need him...
THE PLANE...THE PLANE... If he were still alive he would feel right at home.
Oh well.. I have got to go...
I am busy designing LOBSTER HORNS for Elvis's Lowthers...
thank you very much
Bob
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: UE-468
Date: Tue, 07 Jul 1998 08:42:59 -0700
Source: Sound Digest Archive v01.n335
Hi All,
Does anyone know of this tube (UE-468)? An acquaintence has
some and was inquiring about their suitability for SE use.
It would seem like a considerable undertaking for a novice.
He had some data (see comments below), but not complete.
Any help, esp additional data like Rp and the plate curves
would be appreciated. I am not sure whether he has spares
he would like to sell, I will check.
Dan Marshall
> Dan I have some big new US made tubes here that I have been told are like
> 211 tubes on steriods.. They are about a foot tall and made by the
> UNITED ELECTRONICS COMPANY> and the number on them is UE-468. Am I right to
> assume they would make an interesting amp? They look beautiful.
>
> Was sent this info on them..
>
> FILAMENT = 10V@4.05A
> Mu = 18
> Max Anode Ratings = 2500V@200mA, dissipation 200W
> Typical Anode = 2000V@183mA, output = 280W
> Typical grid = -240V@21mA, driving power 8.4W,
> peak RF grid voltage = 400
>
> Interelectrode Capacitances:
> G-P = 7.0 mmF
> G-F = 8.8 mmF
> P-F = 1.25 mmF
=========================================================================
From: "JF" <jimfl@CyberRamp.net>
Subject: Re: UE-468, and a question
Date: Tue, 7 Jul 1998 22:57:14 -0500
Source: Sound Digest Archive v01.n336
Dan,
I've fired up a UE-468 in one of my amps. I was running it at low voltage
class A2. I don't remember the exact numbers, but it was close to 700V and
170mA plate, +15V on the grid.
I agree, it's a beautiful tube.
I haven't generated the plate characteristics yet. From my notes I found
some rough measurements of the plate resistance taken at zero volts grid
bias (cathode and grid grounded) - at 550V and 100mA, Rp ~4.2kohm; at 850V
and 175mA, Rp ~3.5kohm. I think if you're willing to run the plate voltage
high enough, you might find some useable class A1 power although I'm
guessing that the plate resistance will be somewhat higher than a 211.
Anybody have some info on another (smaller) transmitting triode, the CV-11
tube?
JF
- ----------
> From: Daniel J. Marshall <danmarshall@worldnet.att.net>
> To: sound@deliverator.io.com
> Subject: UE-468
> Date: Tuesday, July 07, 1998 10:42 AM
>
> Hi All,
>
> Does anyone know of this tube (UE-468)? An acquaintence has
> some and was inquiring about their suitability for SE use.
> It would seem like a considerable undertaking for a novice.
> He had some data (see comments below), but not complete.
> Any help, esp additional data like Rp and the plate curves
> would be appreciated. I am not sure whether he has spares
> he would like to sell, I will check.
>
> Dan Marshall
>
> > Dan I have some big new US made tubes here that I have been told are
like
> > 211 tubes on steriods.. They are about a foot tall and made by
the
> > UNITED ELECTRONICS COMPANY> and the number on them is UE-468. Am I
right to
> > assume they would make an interesting amp? They look beautiful.
> >
> > Was sent this info on them..
> >
> > FILAMENT = 10V@4.05A
> > Mu = 18
> > Max Anode Ratings = 2500V@200mA, dissipation 200W
> > Typical Anode = 2000V@183mA, output = 280W
> > Typical grid = -240V@21mA, driving power 8.4W,
> > peak RF grid voltage = 400
> >
> > Interelectrode Capacitances:
> > G-P = 7.0 mmF
> > G-F = 8.8 mmF
> > P-F = 1.25 mmF
=========================================================================
From: Robert Lamarre <rlamarre@rlacoustique.com>
Subject: UL/CSA/CE Requirements
Date: Sun, 1 Nov 1998 17:48:47 -0500
Source: Sound Digest Archive v01.n477
Hi gang,
Does anyone know the regulations regarding the above for tube amps?
I see many amps around the world without any cages or other protective device.
TIA,
========== Robert Lamarre ===========
RL Acoustique, Creator of The Lamhorn
rlamarre@rlacoustique.com------------
www.rlacoustique.com-----------------
ph./fax: 450-653-3461 Canada---------
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: UL/CSA/CE Requirements
Date: Mon, 02 Nov 1998 22:20:32 +0100
Source: Sound Digest Archive v01.n478
At 17:48 1-11-98 -0500, Robert Lamarre wrote:
>Hi gang,
Hi
>Does anyone know the regulations regarding the above for tube amps?
>I see many amps around the world without any cages or other protective
device.
With resect to safety I guess that you need additional measures (like you
mention) and / or explicit warnings in the user manual.
Consult one of the manufacturers that make / sell those amps !
I am an EMC Engineer and from the EMC point of view tube amps shall be
treated as any other audio product
Hope this helps
Guido
>TIA,
>========== Robert Lamarre ===========
>RL Acoustique, Creator of The Lamhorn
>rlamarre@rlacoustique.com------------
>www.rlacoustique.com-----------------
>ph./fax: 450-653-3461 Canada---------
>
>
=========================================================================
From: tronan@orion.it.luc.edu (Thomas Ronan)
Subject: Ultimate DHT tube filament regulator?
Date: Sun, 16 Nov 1997 23:13:38 -0600
Source: Sound Digest Archive v01.n111
Hey all...
Grover has raised some questions which i have been pondering for a long
time: how to get quiet and good sounding dht filaments.
i think that i agree with him that choke filtered dc filaments on dhts
sound almost as good (if not as good) as ac filaments on dc tubes.
nevertheless, with the choke, the sound is better than without, and on a
preamp dht, the dc is essential.
camille and boyle suggested a +/-5v regulated arrangement for heating 10 v
tubes. this can work for 5v tubes too, at the expense of a little
complexity, but what about quiet? how quiet does the regulator get the
filament? i was under the impression that they got rid of a _lot_ of
noise, but is this correct? how does one implement them well?
also, on a filament supply for a 2.5V tube, or the 2.0 or 1.5 v battery
tube type filaments, what can one do? i think the lowest that the variable
regs can go is about 1.5 v each, so a +/- supply is not a viable
option...or is it?
I REALLY WANT TO GET THE FILAMENTS quiet. what can i do?
thanks,
Tom
- ------
Thomas Ronan tronan@orion.it.luc.edu
1045 W. Montana, Chicago, IL 60614 773.528.0882
Lowther Club of America, Chicago Representative
=========================================================================
From: Guido Tent <gtent@ehv.sc.philips.com>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 09:36:02 +0100
Source: Sound Digest Archive v01.n111
Hi,
>>I REALLY WANT TO GET THE FILAMENTS quiet. what can i do?
Ever considered what the influence is of DM variations on the heater ?
There exists CM too
Have a look at that, and you'l be surprised
>How about using multiple stages of low-pass filtering with chokes, instead
>of limiting yourself to just one. You can try LCLC arrangements and see,
>with heaps of capacitance (ie. 30000 or more).
>
>The +/- idea is good. I use that for my DHT output tubes. ALl you need to
>do is make the entire heater supply floating, and then ground the filaments
>at the tube using, say, 2 100ohm resistors going from both sides of the
>filament to ground.
>
>I think shielding is really important, too. I shield all crucial wiring
>internally with copper foil, grounding at one end.
Yoy should ground them at both sides. If not, no current is allowed to pass
your shield, so the magnetic shielding goes zero !
>My chasses are always
>made of 3mm copper (amazing RFI shielding properties!).
Shields like aluminium or iron, the advantage of copper is that it sounds
better, do not know why
>Try running all
>wiring at right angles to each other especially when crossing. I run all
>heaters through one shileld, and all B+s through another, meeting only at
>the tube. A separate power supply with two separate umbilicals helps here.
>And it helps to twist certain wires together...
Shielding heaters only helps if you use mu metal (and connect shield at both
sides), because mu of other metals is far too low to be effective at 100 Hz
or 120 Hz
If the supply and heaters are clean (in all propertioes (DM and CM) you can
run them nicely togheter and your amp will remain quiet
Have fun
Guido
>Rob.
>
>
>
>
" 640K ought to be enough for anybody" , Bill Gates, 1981
Disclaimer: The opinions expressed herin are my personal ones and do not in
any way reflect opinions or policies of my employer.
Guido Tent
Engineer Electro Magnetic Compatibility
Philips Semiconductors Systems Laboratory Eindhoven (PS-SLE)
Building BE303, (Hurksestraat 19)
P.O.Box 218, 5600MD Eindhoven, The Netherlands
Phone: +31-40-27 24553
fax : +31-40-27 22764
- - Let's make things better ! -
E-mail: guido.tent@ehv. sc.philips.com
Seri : gtent@nlsce1
=========================================================================
From: Guido Tent <gtent@ehv.sc.philips.com>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 09:41:17 +0100
Source: Sound Digest Archive v01.n111
At 17:08 17-11-97 +1100, Hugh R. Dean wrote:
>Hey Tom, you wrote:
>
>>I REALLY WANT TO GET THE FILAMENTS quiet. what can i do?
>>
>Not sure of this approach, but have you tried a twin choke, one choke for
>each side of the filament, with two large caps installed to each choke on
>the other rail? Seems to me that the smoothing has to be completely
>symmetrical on each side of the filament so that no one side gets more
>signal than the other.
Some people are getting close !
Keep trying, you are almost there, read one of my today's mails
Guido
>Signal could be connected as usual to the CT of the fil winding.
>
>Cheers,
>
>Hugh R. Dean
>Melbourne, Australia
>
>
>
" 640K ought to be enough for anybody" , Bill Gates, 1981
Disclaimer: The opinions expressed herin are my personal ones and do not in
any way reflect opinions or policies of my employer.
Guido Tent
Engineer Electro Magnetic Compatibility
Philips Semiconductors Systems Laboratory Eindhoven (PS-SLE)
Building BE303, (Hurksestraat 19)
P.O.Box 218, 5600MD Eindhoven, The Netherlands
Phone: +31-40-27 24553
fax : +31-40-27 22764
- - Let's make things better ! -
E-mail: guido.tent@ehv. sc.philips.com
Seri : gtent@nlsce1
=========================================================================
From: Robert Ang <rang@tartarus.uwa.edu.au>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 14:29:29 +0800
Source: Sound Digest Archive v01.n111
>Hey all...
>
>Grover has raised some questions which i have been pondering for a long
>time: how to get quiet and good sounding dht filaments.
>
>i think that i agree with him that choke filtered dc filaments on dhts
>sound almost as good (if not as good) as ac filaments on dc tubes.
>nevertheless, with the choke, the sound is better than without, and on a
>preamp dht, the dc is essential.
>
>camille and boyle suggested a +/-5v regulated arrangement for heating 10 v
>tubes. this can work for 5v tubes too, at the expense of a little
>complexity, but what about quiet? how quiet does the regulator get the
>filament? i was under the impression that they got rid of a _lot_ of
>noise, but is this correct? how does one implement them well?
>
>also, on a filament supply for a 2.5V tube, or the 2.0 or 1.5 v battery
>tube type filaments, what can one do? i think the lowest that the variable
>regs can go is about 1.5 v each, so a +/- supply is not a viable
>option...or is it?
>
>I REALLY WANT TO GET THE FILAMENTS quiet. what can i do?
How about using multiple stages of low-pass filtering with chokes, instead
of limiting yourself to just one. You can try LCLC arrangements and see,
with heaps of capacitance (ie. 30000 or more).
The +/- idea is good. I use that for my DHT output tubes. ALl you need to
do is make the entire heater supply floating, and then ground the filaments
at the tube using, say, 2 100ohm resistors going from both sides of the
filament to ground.
I think shielding is really important, too. I shield all crucial wiring
internally with copper foil, grounding at one end. My chasses are always
made of 3mm copper (amazing RFI shielding properties!). Try running all
wiring at right angles to each other especially when crossing. I run all
heaters through one shileld, and all B+s through another, meeting only at
the tube. A separate power supply with two separate umbilicals helps here.
And it helps to twist certain wires together...
Rob.
=========================================================================
From: "Hugh R. Dean" <aspen@alphalink.com.au>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 17:08:09 +1100
Source: Sound Digest Archive v01.n111
Hey Tom, you wrote:
>I REALLY WANT TO GET THE FILAMENTS quiet. what can i do?
>
Not sure of this approach, but have you tried a twin choke, one choke for
each side of the filament, with two large caps installed to each choke on
the other rail? Seems to me that the smoothing has to be completely
symmetrical on each side of the filament so that no one side gets more
signal than the other.
Signal could be connected as usual to the CT of the fil winding.
Cheers,
Hugh R. Dean
Melbourne, Australia
=========================================================================
From: "Frank Deutschmann" <fdeutsch@bfm.com>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 10:31:42 -0500
Source: Sound Digest Archive v01.n112
On Nov 17, 9:41am, Guido Tent wrote:
> At 17:08 17-11-97 +1100, Hugh R. Dean wrote:
> >Not sure of this approach, but have you tried a twin choke, one choke for
> >each side of the filament, with two large caps installed to each choke on
> >the other rail? Seems to me that the smoothing has to be completely
> >symmetrical on each side of the filament so that no one side gets more
> >signal than the other.
>
> Some people are getting close !
>
> Keep trying, you are almost there, read one of my today's mails
If by this you are hinting at using a common mode choke on the filament
leads, be aware that that approach means that you can no longer use the
center tap of the filament xformer (as the signal is common mode on the
filament supply of a DHT).
Common mode chokes are, however, quite effective on the filament power for
DHT's; follow with a center tapped cap pair, and use a center tapped R pair
to get at the signal. Panasonic makes some really nice units that workd well
in this app; they are designed for common mode filtering of mains supply to
switch mode supplies.
- -frank
=========================================================================
From: Thomas Ronan <tronan@orion.it.luc.edu>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 15:12:17 -0600 ()
Source: Sound Digest Archive v01.n112
> >also, on a filament supply for a 2.5V tube, or the 2.0 or 1.5 v battery
> >tube type filaments, what can one do? i think the lowest that the variable
> >regs can go is about 1.5 v each, so a +/- supply is not a viable
> >option...or is it?
> Yes, they are limited to 1.5V, but that doesn't have to be 1.5V referenced
> to ground.
>
> By floating the secondary of your filament tranny and then adding a 1:1
> resistive divider to the 1.5V output and then grouding the middle of that
> divider, you reference the regulator output to +0.75V, thus generating
> +/-0.75VDC.
John, this is logically correct, but not what I meant. By true +/- 1.5v
supply, I meant two regulated supplies, one being +0.75 volts, the other
being - 0.75 volts with the common ground shared as the center tap.
However, one could build two supplies, one +1.5V and one -1.5v and use a
voltage divider on the output of each. why? I don't know that it would
be any better, but I suppose that it is there as an option...
Camille/Boyle insinuated that they got a sonic improvment when they
switched to this +/- regulator approach...they were using fixed bias, and
so had a super low impedance to ground, right at the filament. No need to
run it back through the tranny, or through a balancing pot or through CT
resistors.
Tom
=========================================================================
From: Thomas Ronan <tronan@orion.it.luc.edu>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 15:20:04 -0600 ()
Source: Sound Digest Archive v01.n112
Frank wrote;
> Common mode chokes are, however, quite effective on the filament power
for
> DHT's; follow with a center tapped cap pair, and use a center tapped R pair
> to get at the signal. Panasonic makes some really nice units that workd well
> in this app; they are designed for common mode filtering of mains supply to
> switch mode supplies.
Ahh... this is an interesting point. What about those mains filters that
are supposed to reduce RF problems? What if they were used as a filter
stage in a filament supply. they usually have two chokes in series, one
with each leg of the supply, and two caps to ground, with the ground at
the center of the two output caps. Would this not create a common mode
filter as you suggest (albeit at the wrong frequencies for filtering
filament noise)?
So, bridge rectify the supply, use two big input caps with a center tap
as 'ground', use two chokes, one on each leg, with another filter cap
after each choke, again with ct as ground, and connect this to the
filaments, and connect the cathode resistor to ground? Or connect the
previous setup to two regulators, one for the positive and one for the
negative votlages, and then to the filaments? Is this enough? Will it be
super clean?
Keep in mind that these chokes are not small...they are the size of a
medium sized B+ choke after all. I'm using 0.03H at 1.4A. What
inductance is required for good filtering? If this is just a 1/2Pif
question, then what are the f's we are dealing with here in real terms?
Filament noise seems to have more HF components than B+, but I sense that
I am wrong to believe this.
Tom
=========================================================================
From: Thomas Ronan <tronan@orion.it.luc.edu>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 15:21:15 -0600 ()
Source: Sound Digest Archive v01.n112
> >Common mode chokes are, however, quite effective on the filament power for
> >DHT's; follow with a center tapped cap pair, and use a center tapped R pair
By the way, what is a common mode choke?
(duh)
Tom
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 15:44:59 -0600
Source: Sound Digest Archive v01.n112
Another interesting find in dealing with this 40 is that the hum is reduced
by using a larger cathode bypass cap. The cathode resistor is 12K-15K due
to the the very low current draw of this tube, and I had assumed that
10-20uF would be more than enough. But putting a larger cap on the bypass
significantly reduces the noise. I know from RDH that bypassing DHTs and
early cathode-types can reduce hum. Also, this tube has an extremely high
plate resistance, along the lines of 150K. Guido, you mentioned the other
day that the cathode bypass also has to do with the plate resistance in
conjunction with the cathode resistor. It was a bit over my head, perhaps
you could explain more fully? Could this be a case in point? If the
cathode bypass gets too large, could there be a problem with phase shift or
something else?
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: "Hugh R. Dean" <aspen@alphalink.com.au>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Tue, 18 Nov 1997 05:40:16 +1100
Source: Sound Digest Archive v01.n112
Hi Frank, you wrote:
>
>If by this you are hinting at using a common mode choke on the filament
>leads, be aware that that approach means that you can no longer use the
>center tap of the filament xformer (as the signal is common mode on the
>filament supply of a DHT).
>
>Common mode chokes are, however, quite effective on the filament power for
>DHT's; follow with a center tapped cap pair, and use a center tapped R pair
>to get at the signal. Panasonic makes some really nice units that workd well
>in this app; they are designed for common mode filtering of mains supply to
>switch mode supplies.
Yes, I was hinting at this. And I admit to confusion about where to tap in
the signal. Thank you for explaining it.
Cheers,
Hugh R. Dean
Melbourne, Australia
=========================================================================
From: spence barton <ence-ack@rio.com>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 15:43:25 -0800
Source: Sound Digest Archive v01.n113
>At 03:12 PM 11/17/97 -0600, Thomas Ronan wrote:
>>
>>
>>Camille/Boyle insinuated that they got a sonic improvment when they...
^^^^^^^^^^
Anyone besides me think that Young Tom is coming along well in law school?
I think he's really getting the hang of counter-suggestibility. ;-) There
is a lingering sneaking dishonesty that surrounds the word "insinuation"
for me. Kind of unsavory. I hope I don't ever have to be cross-examined by
the future Middle Aged Tom. :-) "Ladies and Gentleman of the jury, the
witness who _insinuated_ that his name is Spence..."
Anyway Tom, all gentle kidding aside, if John Camille insinuated in a
sneaky and unsavory fashion that he got an improvement, I'd be inclined to
try it. I had a couple of very educational (for me) talks with him at VSAC
and he is extremely knowledgable and open to all kinds ideas. I think there
is a great deal to be gained from all kinds of common mode strategies.
spence
spence barton
ence-ack@rio.com
=========================================================================
From: John Levreault <jlevro@shore.net>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 17:49:15 -0500
Source: Sound Digest Archive v01.n113
At 03:12 PM 11/17/97 -0600, Thomas Ronan wrote:
>
>
>Camille/Boyle insinuated that they got a sonic improvment when they
>switched to this +/- regulator approach...they were using fixed bias, and
>so had a super low impedance to ground, right at the filament. No need to
>run it back through the tranny, or through a balancing pot or through CT
>resistors.
>
>
Gotcha. I'll keep my eyes open. There's a lot going on these days in real
low voltage regulators.
JL
=========================================================================
From: "Frank Deutschmann" <fdeutsch@bfm.com>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 17:51:32 -0500
Source: Sound Digest Archive v01.n113
On Nov 17, 3:12pm, Thomas Ronan wrote:
> Camille/Boyle insinuated that they got a sonic improvment when they
> switched to this +/- regulator approach...they were using fixed bias, and
> so had a super low impedance to ground, right at the filament. No need to
> run it back through the tranny, or through a balancing pot or through CT
> resistors.
This is a pretty good approach, but all the cautions about regulated supplies
apply: the impedance to ground through these power supplies definitely varies
across the audio spectrum! I found it especially interesting that they liked
a pair +/- supplies better than a single supply: as the pair of supplies is
in AC parallel to ground (from the signal POV), using a pair cuts the supply
impedance in half, but, probably much more importantly, reduces the effect of
any impedance variation across the audio band!
To see why this is so, consider a single supply with say 1 Ohm AC impedance.
Now, if we replace this single filament supply with a pair of filament
supplies, each half the voltage, assuming a similar single supply impedance,
we get a net AC impedance to ground of 0.5 Ohms: the impedance to ground is
cut in half, as expected. Now, consider a supply which has a 0.5 Ohm
impedance at 10 Hz, but the impedance rises to 1 Ohm at 20kHz; this is a rise
across the audio band of 0.5 Ohm. If we replace this single supply with a
pair of +/- supplies of the same design, we will now see a net impedance of
0.25 Ohms at 10Hz, and 0.5 Ohms at 20kHz: the rise across the audio band is
now only 0.25 Ohms. When multiplied by the mu of the tube, the difference in
the two variations is much larger still.
A further benefit of dual supplies is that the noise is increased less over a
comparable single supply.
Considering that any impedance in the cathode of the tube is multiplied by
the tube mu and transfered to the Zout of the tube (cathode impedance is
local negative current feedback), it seems to me that maintaining a very
small and vary flat cathode impedance is of utmost importance to Good Sound.
Of course, there are many factors in the Camille/Boyle amp, but I thought
their preference for dual +/- regulated filament supplies was rather telling;
it fit well with theory from my POV. (I strongly believe that the non-flat
impedance of regulated supplies over the audio spectrum has a lot to do with
why regulated DC filaments are frowned upon by many, for DHT's. The noise
and instability aspects can't help, either. The Camile/Boyle approach
adresses all of these issues, though.)
- -frank
=========================================================================
From: tronan@orion.it.luc.edu (Thomas Ronan)
Subject: Re: Ultimate DHT tube filament regulator?
Date: Mon, 17 Nov 1997 18:35:33 -0600
Source: Sound Digest Archive v01.n113
At 5:43 PM 11/17/97, spence barton wrote:
>>At 03:12 PM 11/17/97 -0600, Thomas Ronan wrote:
>>>
>>>
>>>Camille/Boyle insinuated that they got a sonic improvment when they...
> ^^^^^^^^^^
>
>Anyone besides me think that Young Tom is coming along well in law school?
>I think he's really getting the hang of counter-suggestibility. ;-) There
You know, I didn't even realize that I 'said' it.
>is a lingering sneaking dishonesty that surrounds the word "insinuation"
>for me. Kind of unsavory. I hope I don't ever have to be cross-examined by
To me, it means that 'he said' he got an improvement, and even if I trust
him or his abilities, I don't necessarily find pleasant in audio what he
finds in audio. At least, I guess it meant all that...it just typed out of
my fingers!
*grin*
Tom
- ------
Thomas Ronan tronan@orion.it.luc.edu
1045 W. Montana, Chicago, IL 60614 773.528.0882
Lowther Club of America, Chicago Representative
=========================================================================
From: "Hugh R. Dean" <aspen@alphalink.com.au>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Tue, 18 Nov 1997 07:13:25 +1100
Source: Sound Digest Archive v01.n113
Hi Tom, you wrote:>
>By the way, what is a common mode choke?
>
Two chokes wound on a common former/core. Each inductor is electrically
isolated, but magnetically coupled.
A most interesting animal.
Cheers,
Hugh
=========================================================================
From: Guido Tent <gtent@ehv.sc.philips.com>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Tue, 18 Nov 1997 09:25:20 +0100
Source: Sound Digest Archive v01.n113
At 10:31 17-11-97 -0500, Frank Deutschmann wrote:
>On Nov 17, 9:41am, Guido Tent wrote:
>> At 17:08 17-11-97 +1100, Hugh R. Dean wrote:
>> >Not sure of this approach, but have you tried a twin choke, one choke for
>> >each side of the filament, with two large caps installed to each choke on
>> >the other rail? Seems to me that the smoothing has to be completely
>> >symmetrical on each side of the filament so that no one side gets more
>> >signal than the other.
>>
>> Some people are getting close !
>>
>> Keep trying, you are almost there, read one of my today's mails
>
>If by this you are hinting at using a common mode choke on the filament
>leads, be aware that that approach means that you can no longer use the
>center tap of the filament xformer (as the signal is common mode on the
>filament supply of a DHT).
You are right. One should center them with tw resitors between choke and tube
>Common mode chokes are, however, quite effective on the filament power for
>DHT's; follow with a center tapped cap pair, and use a center tapped R pair
>to get at the signal.
Yup, and short them to the reference, using two caps !
Guido
Panasonic makes some really nice units that workd well
>in this app; they are designed for common mode filtering of mains supply to
>switch mode supplies.
>
>-frank
>
>
=========================================================================
From: Guido Tent <gtent@ehv.sc.philips.com>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Tue, 18 Nov 1997 09:46:41 +0100
Source: Sound Digest Archive v01.n113
At 15:44 17-11-97 -0600, Grover Gardner wrote:
>Another interesting find in dealing with this 40 is that the hum is reduced
>by using a larger cathode bypass cap. The cathode resistor is 12K-15K due
>to the the very low current draw of this tube, and I had assumed that
>10-20uF would be more than enough. But putting a larger cap on the bypass
>significantly reduces the noise. I know from RDH that bypassing DHTs and
>early cathode-types can reduce hum. Also, this tube has an extremely high
>plate resistance, along the lines of 150K. Guido, you mentioned the other
>day that the cathode bypass also has to do with the plate resistance in
>conjunction with the cathode resistor. It was a bit over my head, perhaps
>you could explain more fully?
Yep, I can. It has to do with transconductance, not with plate resistance
(allthough these are related via mu)
I you look "into" the cathode, you "see" an impedance. In a common cathode
circuit, with the grid tied to reference by a grid resistor, this impedance
equals 1/s were s is the transconductance. Example ECC83/12AX7 were s =
about 1 mA/V you will get 1 k-ohm
This is also the output impedance of a cathode follower (asuming a standard
circuit)
It means that you have a source on top of the decoupling-cap, this source is
in prallel with the cathode resistor. The source has a low impedance, and
therfore needs to be considered when calculating the rol-off due to the
decoupling cap
>Could this be a case in point? If the
>cathode bypass gets too large, could there be a problem with phase shift or
>something else?
Phase is related to frequency and rol-off
With the bigger decoupling cap, your rol-off shifts further below 120 Hz,
giving less local feedback due to cathode degeneration. Mu times the
impedance at the cathode (mu*Rc) is added to the plate impedance Ra of the
tube. This gives an anode impedance of (Ra + mu*Rc). This contribution is
reduced, the ratio (Ra + mu*Rc) and the external plate resistor Rplate is
also reduced, yielding a higher suppresion from the B+ line.
I suggest you check B+ for a ripple
Have fun
Guido
>Grover Gardner
>groverg@bellatlantic.net
>
>
>
>
" 640K ought to be enough for anybody" , Bill Gates, 1981
Disclaimer: The opinions expressed herin are my personal ones and do not in
any way reflect opinions or policies of my employer.
Guido Tent
Engineer Electro Magnetic Compatibility
Philips Semiconductors Systems Laboratory Eindhoven (PS-SLE)
Building BE303, (Hurksestraat 19)
P.O.Box 218, 5600MD Eindhoven, The Netherlands
Phone: +31-40-27 24553
fax : +31-40-27 22764
- - Let's make things better ! -
E-mail: guido.tent@ehv. sc.philips.com
Seri : gtent@nlsce1
=========================================================================
From: Guido Tent <gtent@ehv.sc.philips.com>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Tue, 18 Nov 1997 09:49:19 +0100
Source: Sound Digest Archive v01.n113
At 15:21 17-11-97 -0600, Thomas Ronan wrote:
>> >Common mode chokes are, however, quite effective on the filament power for
>> >DHT's; follow with a center tapped cap pair, and use a center tapped R pair
>
>
>By the way, what is a common mode choke?
Two windings on one core (so magnetically). Winded such that both
contibutions of the flux in the core (Due to current in the windings) do
compensate
The result is no flux at all, giving a high impedance for the PAIR OF WIRES.
This impedance is usually called common mode impedance, and denoted in mH os so
Guido
>(duh)
>
>Tom
>
>
"to be EMC or not to be EMC, that's the question"
Guido Tent
Engineer
Electro Magnetic Compatibility
Philips Semiconductors Systems Laboratory Eindhoven (PS-SLE)
Building BE303, (Hurksestraat 19)
P.O.Box 218, 5600MD Eindhoven, The Netherlands
Phone: +31-40-27 24553
fax : +31-40-27 22764
E-mail: guido.tent@ehv.sc.philips.com
Seri : gtent@nlsce1
- - Let's make things better ! -
=========================================================================
From: Jonathan Morrison <ppdiva@pipeline.com>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Tue, 18 Nov 1997 18:43:29 -0500
Source: Sound Digest Archive v01.n114
What about a car battery? Seems like a couple of Diehards, a switch, and a
cheap charger would work nicely. JDM
=========================================================================
From: Grover Gardner <groverg@bellatlantic.net>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Tue, 18 Nov 1997 22:01:01 -0600
Source: Sound Digest Archive v01.n114
At 9:46 AM +0100 11/18/97, Guido Tent wrote:
>At 15:44 17-11-97 -0600, Grover Gardner wrote:
>>Another interesting find in dealing with this 40 is that the hum is reduced
>>by using a larger cathode bypass cap. The cathode resistor is 12K-15K due
>>to the the very low current draw of this tube, and I had assumed that
>>10-20uF would be more than enough. But putting a larger cap on the bypass
>>significantly reduces the noise. I know from RDH that bypassing DHTs and
>>early cathode-types can reduce hum. Also, this tube has an extremely high
>>plate resistance, along the lines of 150K. Guido, you mentioned the other
>>day that the cathode bypass also has to do with the plate resistance in
>>conjunction with the cathode resistor. It was a bit over my head, perhaps
>>you could explain more fully?
>
>Yep, I can. It has to do with transconductance, not with plate resistance
>(allthough these are related via mu)
>
>I you look "into" the cathode, you "see" an impedance. In a common cathode
>circuit, with the grid tied to reference by a grid resistor, this impedance
>equals 1/s were s is the transconductance. Example ECC83/12AX7 were s =
>about 1 mA/V you will get 1 k-ohm
>
>This is also the output impedance of a cathode follower (asuming a standard
>circuit)
>
>It means that you have a source on top of the decoupling-cap, this source is
>in prallel with the cathode resistor. The source has a low impedance, and
>therfore needs to be considered when calculating the rol-off due to the
>decoupling cap
>
>>Could this be a case in point? If the
>>cathode bypass gets too large, could there be a problem with phase shift or
>>something else?
>
>Phase is related to frequency and rol-off
>
>With the bigger decoupling cap, your rol-off shifts further below 120 Hz,
>giving less local feedback due to cathode degeneration. Mu times the
>impedance at the cathode (mu*Rc) is added to the plate impedance Ra of the
>tube. This gives an anode impedance of (Ra + mu*Rc). This contribution is
>reduced, the ratio (Ra + mu*Rc) and the external plate resistor Rplate is
>also reduced, yielding a higher suppresion from the B+ line.
>
>I suggest you check B+ for a ripple
>
>Have fun
>
>Guido
Bingo, Guido! VERY high plate resistor, 800K, leading to high amount of B+
noise--that's what made the bugger so noisy. Thank you. So the answer
would be to add a large decoupling filter and use a smaller plate resistor.
Aha!
Grover Gardner
groverg@bellatlantic.net
=========================================================================
From: MHuber@t-online.de (Manfred Huber)
Subject: Re: Ultimate DHT tube filament regulator?
Date: Wed, 19 Nov 97 16:52:39 -0100
Source: Sound Digest Archive v01.n114
Guido,
>If you look "into" the cathode, you "see" an impedance. In a common cathode
>circuit, with the grid tied to reference by a grid resistor, this impedance
>equals 1/s were s is the transconductance. Example ECC83/12AX7 were s =
>about 1 mA/V you will get 1 k-ohm
1/s (or 1/gm) is a valid approximation for the cathode impedance of a
high mu tube with it's plate tied to B+. The exact value is Ri/(mu+1).
When we are talking about the cathode impedance of an anode follower
we also have to consider the effect of the plate load resistor Rp.
In this case the impedance seen when looking into the cathode is
(Rp+Ri)/(mu+1)
Regards
Manfred
- ------------------
Manfred Huber
MHuber@t-online.de
- ------------------
=========================================================================
From: Grego Sanguinetti <grego@latticesemi.com>
Subject: Re: Ultimate DHT tube filament regulator?
Date: Wed, 19 Nov 1997 16:03:25 -0800 (PST)
Source: Sound Digest Archive v01.n115
On Tue, 18 Nov 1997, Jonathan Morrison wrote:
> What about a car battery? Seems like a couple of Diehards, a switch, and a
> cheap charger would work nicely. JDM
Oh, and what Dunker Factor! sheesh! -grego
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: Ultrapath ??
Date: Thu, 10 Sep 1998 14:11:08 PDT
Source: Sound Digest Archive v01.n420
Hi all,
>if your output cathode resistor is a solen or oil (non-polar 500V
>or so) give the ultrapath a shot...
I take it you are talking about the Cathode Cap.....
However I agree to a point. I would also look at re-referencing the
Input directly to the Cathode....
Calls for an Interstage trannie of course....
I think this "Ultrapath" Thingey is just MADE for any SE Poweramp....
Love the Concept....
Now how do I implement this for my 300B PP/SE Switchable Amp which is
brewing heftyly.... (Waiting for the IT Quotes)....
Kind regards Thorsten.
======================================
e-mail:
Thorsten@tnt-audio.com
Visit TNT-Audio on the Web - the only advertising
free audio web-zine.
http://www.tnt-audio.com
======================================
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
=========================================================================
From: dslagle@earthlink.net (dave slagle)
Subject: Ultrapath ??
Date: Thu, 10 Sep 1998 16:25:32 -0400
Source: Sound Digest Archive v01.n420
ok... here is another request for all of you 'spermenters out there...
(which people will probably discuss til no end and never TRY like shared
cathode R from bob d.)
if your output cathode resistor is a solen or oil (non-polar 500V or so)
give the ultrapath a shot... all you have to do is lift the grounded side
of the cap and tie it to the top of the last B+ cap.
i did it and it made a big change... I still can't believe it... My biggest
complaint about my lowthers were how they smear more complex music, but the
switch to the ultrapath approach really cleaned up more complex recordings.
I don't hear a big difference between black gates and solens in the cathode
of my output tubes... I go back and fourth and its a coin toss, but there
is a big difference when the ultrapath hookup is used.
in any event if your system will allow give it a try...
hell just connect an appropriate cap from the cathode to the B+ and be done
with it...
with the B+ to cathode cap in place I don't notice a difference with or
without the BG around the cathode R...but slapping that ultrapath cap in
ther sure makes the sound more focused to me.
come on... give it a try... whaddya got to lose???
dave
=========================================================================
From: Grover Gardner <groverg@postoffice.att.net>
Subject: Re: Ultrapath ??
Date: Thu, 10 Sep 1998 16:46:43 -0500
Source: Sound Digest Archive v01.n420
At 4:25 PM -0400 9/10/98, dave slagle wrote:>with the B+ to cathode cap in
place I don't notice a difference with or
>without the BG around the cathode R...but slapping that ultrapath cap in
>ther sure makes the sound more focused to me.
Well, then I guess that's not causing Chris's hum, eh?
Grover Gardner
groverg@postoffice.att.net
=========================================================================
From: "Chris Beck" <cbeck@brewercompany.com>
Subject: Re: ultrapath
Date: Fri, 11 Sep 1998 11:05:52 -0500
Source: Sound Digest Archive v01.n421
If anyone has any profound thoughts or ideas this weekend, please e-mail me
at home at n9zes@execpc.com.
I'll see if I can get the list going to my home PC as well. I might go
into withdrawal over the weekend! :-))
Chris Beck
See my web page at: http://www.execpc.com/~n9zes/index.htm
=========================================================================
From: "Larry D. Moore" <l-moore@onu.edu>
Subject: Ultra path
Date: Wed, 16 Sep 1998 07:38:43 -0400
Source: Sound Digest Archive v01.n423
Well, I tried the Ultra path on my driver stage (Tango NC-14 with
7119).....used a SCR 20uf/630V. This apparently wasn't enough cap, so I
added some oils in parallel. A bit of a different perspective. I'll pass.
It just seemed to suck the life out of the music. I lost perspective and
involvement. So, I tried it. Actually, I think I could make this sound
good; but, it would take changing some other things too. Like power supply
for example. This is an interesting thought. I wonder if you are, in
fact, trying to offset the reactance of the primary of the tx with the
reactance of the cap. Thus making a "real" ie.) resistive load. Perhaps
this works best with txs which have some characteristic or short coming if
you will. Any thoughts?
L.D. Moore
=========================================================================
From: Grover Gardner <groverg@postoffice.att.net>
Subject: Re: Ultra path
Date: Wed, 16 Sep 1998 10:13:14 -0500
Source: Sound Digest Archive v01.n424
At 7:38 AM -0400 9/16/98, Larry D. Moore wrote:
>Well, I tried the Ultra path on my driver stage (Tango NC-14 with
>7119).....used a SCR 20uf/630V. This apparently wasn't enough cap, so I
>added some oils in parallel. A bit of a different perspective. I'll pass.
> It just seemed to suck the life out of the music. I lost perspective and
>involvement. So, I tried it. Actually, I think I could make this sound
>good; but, it would take changing some other things too. Like power supply
>for example. This is an interesting thought. I wonder if you are, in
>fact, trying to offset the reactance of the primary of the tx with the
>reactance of the cap. Thus making a "real" ie.) resistive load. Perhaps
>this works best with txs which have some characteristic or short coming if
>you will. Any thoughts?
Interesting, LD. If I had any bypass caps in my amps I'd try this on the
output stage, but it's all fixed bias! :-( How are you running that 7119?
Grover Gardner
groverg@postoffice.att.net
=========================================================================
From: Chris Beck <n9zes@execpc.com>
Subject: Ultrapath
Date: Mon, 14 Dec 1998 12:07:57 -0600
Source: Sound Digest Archive v01.n537
OK gang, here's the scoop.
Put the preamp on the board. Added a second choke of 10H and another
100uF of cap after power supply. So, now I have: 6X4, 2K ohm, 100uF,
20H, 100uF, 10H, 100uF, then into the linestage. I also had good
success with a 500 ohm resistor in place of the choke. I just think the
choke sounds a little better.
It's dead quiet. Power supply hum is zip. I just have the faintest
hum that the OPT's are picking up directly. Basically inaudible. I
also went to 100K pot for the input, and gained a huge amount of HF
extension. I know the 500K was causing my phono stage to stink, but
didn't realize the CD in was as affected. I guess I learned something
here. It sounds even more fabulous now.
So, while the preamp looks like a science fair project (again), I'll
revamp the chassis a little and replace the RCA phono stage with a new
design to try. Gotta add another hole for a third tube in the phono
area.
So, I hope to have it all back together in a few weeks, and I'll let
everyone know how it sounds.
Chris Beck
see my webpage at: http://www.execpc.com/~n9zes
=========================================================================
From: RALPH POWER <POWER.RALPH@epamail.epa.gov>
Subject: Ultrapath AMP
Date: Thu, 10 Sep 1998 15:33:15 -0400
Source: Sound Digest Archive v01.n420
Hi All,
Chris said :
>Regarding the cap between the B+ and cathode. This is the essence of the
>Ultrapath. He said this is how it works: All transformers need a return
>path for the AC signal component on the primary. Where does this go? Back
>through the power supply to the last cap, where it's shunted to ground.
>Then, this signal comes all the way back to the cathode of the tube through
>what? Another big capacitor. The cap in this circuit neatly sidesteps
>going through 2 separate capacitors that may even be electrolytic (yuck).
>It is an old Western Electric trick.
In the past couple of days others have eluded to this trick as on old WE trick.
Well, is this doable on a SE output tube, say a 2A3, in place of the traditional
cathode resistor or am I dreaming ? What value cap would be required there ?
Should I wear body armor if I try it ? Would it explode or catch fire ?
It really looks interesting....
Any comments appreciated,
- Ralph (Rural Alien Life PHorm)
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: Ultrapath AMP
Date: Thu, 10 Sep 1998 21:15:57 -0700
Source: Sound Digest Archive v01.n420
RALPH POWER wrote:
> ...Ultrapath snipped...
> In the past couple of days others have eluded to this trick as on old WE trick.
>
> Well, is this doable on a SE output tube, say a 2A3, in place of the traditional
> cathode resistor or am I dreaming ? What value cap would be required there ?
> Should I wear body armor if I try it ? Would it explode or catch fire ?
Presumably the RC time constant (40 Hz for 100 ohms/40uF) should be at
or below the LF limit.
- -Paul Joppa
=========================================================================
From: "=?ISO-8859-1?Q?Torbj=F8rn_Lien?=" <mdrivekl@online.no>
Subject: Re: Ultrapath AMP
Date: Sat, 12 Sep 1998 11:41:05 +0200
Source: Sound Digest Archive v01.n421
Hello Cris,-all.
Guess I should through in my 2 cent's worth on this:
The circuit:
If I get it right it is something like this: Common
cathode coupled amp with x-former load.This series
circuit is shunted by a cap. (40µF was it?) The amp
is connected to its surroundings with a series
resistor from top of x-former to B+.(Was it 100 R?)
Another series resistor to B-. (That was 560R?)
The B- is called GND, and receives the gridleak.
The drop over the 560R provides bias voltage.
If basically like over, this is *really* bad
construction practice.It goes contrary to every rule
on how to execute a stage properly. No wonder it hums.
*I do not believe* that this is an old trick from
Western Electric. (Huh, I wouldn't even suspect the
Italian firm Geloso for similar executions either!!)
On the other hand, it was quite common in the old days
for amps to be shunted with *series connected capasitors*.
Ex: To handle the high DC potential over the 2. stage in
a DC-coupled amp.The first Loftin&White amps did it like
this: One cap from B+ to cathode. Then one from cathode
to gnd.But this was also usually a part of some anti-
hum circuit.
The grave fault with this circuit is that the grid is
not referenced at *the same place* as the cathode,
both vs output. So, this is *no longer* a common
cathode amp.("common cathode": That this element is
"common" to both the input and output circuit.)
Look at your circuit: The tube works as an amp by
varying the potential between cathode and grid. So
you do by imposing input signal. But *in series* with
this input signal is current through a resistor,
develloping a *noice signal*.Hell,-you could provide
bias by another means, substitute the resistor with
a wire, a few inches of metal chassis,-*It would
still hum !!*
This is *not* sound practices, and I'm amazed that
someone did propose this circuit to you. I'm also
amazed that no one on this list pointed this out.
(oh well,I guess you tried Kurt,-)
1:To get a *real* common cathode stage, see to it that
the input and output circuit are referenced at the
exact same place.
2:If you then will go for the "no series dropping
component/fixed bias topology" you have no choice
but to impose a grid input DC blocking cap, a
separate negative bias supply, and do it the
"normal" way.
Hope this helps
:)Torbjoern Lien
>
>
>
>
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: Ultrapath AMP
Date: Sat, 12 Sep 1998 16:41:32 GMT
Source: Sound Digest Archive v01.n422
On Sat, 12 Sep 1998 11:41:05 +0200, "Torbjørn Lien"
<mdrivekl@online.no> wrote:
>The amp
>is connected to its surroundings with a series
>resistor from top of x-former to B+
No. The "top" of the transformer is connected directly to B+, at the
output of a CLC pi filter.
- --dnb
=========================================================================
From: dslagle@earthlink.net (Dave Slagle)
Subject: Re: Ultrapath AMP
Date: Sat, 12 Sep 1998 21:06:46 -0700 (PDT)
Source: Sound Digest Archive v01.n422
>
>> No. The "top" of the transformer is connected directly to B+, at
>> the output of a CLC pi filter. --dnb
in the circuit referenced there is a 100 ohm resistor in place... but this
topology in general is not a source of hum...
>Ok,-but that in particular makes no difference to
>my initial remarks,or the circuit's gnd'ing errors in particular.
this makes the huge assumption that these are errors... many times our ears
have told us something that conventional wisdom has said is wrong... if we
followed the correct approach to everything we wouldn't be using tubes...
it amazes me how hypocritical we can be... on one hand we can argue the
differences between different topologies using "science" to defend our
point... but when questioned on the reason we use tubes... "they sound
better" is the only argument we can put fourth... how can we accept
this... maybe even put fourth a hypothesis as to why... but then turn
around... based on science... and discount something else... unless of
course we have also tried it...
In looking at the ultrapath preamp circuit.. a few things caught my eye...
I would never use a resistor anywhere in a power supply, particularly a
1.2K after the rectafier, and an unbypassed on at the top of the
transformer... that was the designers choice.. he put the circuit out
there... I hate to parrot herbie here, but build it as he did... if you
don't like it make it better or shut up... don't discount it because you
have different preferences...
think about the idea that 90% of the world believes all stereo's sound the
same... and 9% reads stereophile... we are less than 1% who shun all of
that... yet ironically use the same arguments against each other that they
use against us.
i kinda think if we cannot measure what we like in a system (yet)... then
outside of the basic functionality test equipment and science just point us
in a direction, and our ears must be the guide. even in the most simple
amp the possiblities are endless... none of this happens in perfect
vaccuum... but i must admit 10 -6 torr is a good starting point
how bizarre
dave
=========================================================================
From: "=?ISO-8859-1?Q?Torbj=F8rn_Lien?=" <mdrivekl@online.no>
Subject: Re: Ultrapath AMP
Date: Sat, 12 Sep 1998 21:07:18 +0200
Source: Sound Digest Archive v01.n422
Torbjørn Lien wrote:
>
> >The amp
> >is connected to its surroundings with a series
> >resistor from top of x-former to B+
David Barnett wrote:
> No. The "top" of the transformer is connected directly to B+, at
> the output of a CLC pi filter. --dnb
Ok,-but that in particular makes no difference to
my initial remarks,or the circuit's gnd'ing errors in particular.
:TL
=========================================================================
From: "=?ISO-8859-1?Q?Torbj=F8rn_Lien?=" <mdrivekl@online.no>
Subject: Re: Ultrapath AMP
Date: Sun, 13 Sep 1998 23:56:46 +0200
Source: Sound Digest Archive v01.n422
Hello Dave.
> this makes the huge assumption that these are errors... many
> times our ears have told us something that conventional wisdom
> has said is wrong... if we followed the correct approach to
> everything we wouldn't be using tubes...
> it amazes me how hypocritical we can be... on one hand we can
> argue the differences between different topologies using
> "science" to defend our point... but when questioned on the
> reason we use tubes... "they sound better" is the only argument > we
can put fourth... how can we accept this... maybe even put
> fourth a hypothesis as to why... but then turn around... based
> on science... and discount something else... unless of course
> we have also tried it...
>
[snip]
I'm not sure how to approach this,- I would just say that to
allow one fault,-for gaining one advantage anotherplace *can* indeed
work out. If that is what we want. But then we have to
be *aware* on how to "omit" or passivate that fault.And
recognice the fault as just that in the first place.
I'm not sure if the designer of this circuit was aware , that
he was putting a noise generator into circuit.Cause if he was, he would
have emphasized strongly on the importance of a *noise-free* PSU,
especially common mode vice, and suggest some very clever grounding and
screening techniques. And he would still have Cap-bypassed the 510R
drop resistor.
It seems that Chris Beck afterall has got his amp to work ok,
that is good, but it doesn't make the circuit more "sound"
nonetheless. The noise is still there, but he has probably
managed to push it below, and "hide" it in the noise-floor
of the rest of his system. Try this topology as RIAA-input:
It will never work.
My initial post wasn't meant to be so much about the circuit itselves,
what I was thinking of was all the rather cunning suggestions to get
rid of the noice.Very few of those showed any actual *understanding* of
the circuit problem itselves,-
This is important: Cause how can we hope to *achieve* what we want,if
our *understanding* of the various "building blocks" is limited to just
a few,-or just a few sides? I fully support anyones urge to create
something unique, but to do that,
you have to *know* your material.
This is the foundation on any craft:You have to know your
colours to set up a palette,-or all the possibilyties *and* limitations
of wood, if you're a carpenter,-(or a sculpter
with wood as your material.)
Or you can cheat,-and get around the problems if lucky,-
It might sometimes take you forward, but the trial'n erroring
will for sure take it's time,-
:TL
=========================================================================
From: Thomas Danley <Tom@ppci.com>
Subject: Re: Ultrapath AMP
Date: Mon, 14 Sep 1998 12:45:13 -0500
Source: Sound Digest Archive v01.n422
Dave Slagle wrote:
> this makes the huge assumption that these are errors... many times our ears
> have told us something that conventional wisdom has said is wrong... if we
> followed the correct approach to everything we wouldn't be using tubes...
> it amazes me how hypocritical we can be... on one hand we can argue the
> differences between different topologies using "science" to defend our
> point... but when questioned on the reason we use tubes... "they sound
> better" is the only argument we can put fourth... how can we accept
> this... maybe even put fourth a hypothesis as to why... but then turn
> around... based on science... and discount something else... unless of
> course we have also tried it...
>
Hi
As one who has worked in electronics for the last 28+ years, mostly in audio,
including an amplifier company during the evolution of solid state, would like
to comment on the above regarding "science" and a frequent tone on this list..
Science IS how things work regardless of ones personal opinion of the merits of
one approach vs another. Science knowledge is then applied to form the rules
for engineering.
Solid state power devices were heralded by science as allowing smaller
packages, handling higher currents and powers and greater efficiency, all of
which continue to be true.
On the other hand, the companies that sold solid state products all have
marketing departments which transmogrify science facts into marketing hype,
THEY are the ones that say solid-state is better etc. etc.
One should not confuse what they read in hi-fi / Stereo trade publications as
science or even real technical information, Audio, Stereopile and on and on ARE
marketing tools, not to be confused with a reliable source of technical
information.
There is a world of difference between marketing lore and scientific fact and
similar to the "new age" movement in general, science is often painted with a
broad brush as being out of touch with reality.
Interestingly, the less one knows about science, the more extreme peoples view
seems to be.
Measurements for example tell you the answer to the question you ask (with the
instrument) such as
what is the THD with a sine wave ? or what does frequency response look like.
It is the marketing department which removes the wiggles from the response
curve or determines that the lower the THD, the better a device will sound with
music etc. Only your ears can tell you what something sounds like to you.
> In looking at the ultrapath preamp circuit.. a few things caught my eye...
>
> I would never use a resistor anywhere in a power supply, particularly a
> 1.2K after the rectafier, and an unbypassed on at the top of the
> transformer... that was the designers choice.. he put the circuit out
> there... I hate to parrot herbie here, but build it as he did... if you
> don't like it make it better or shut up... don't discount it because you
> have different preferences...
>
Normally one would want to have a low impedance power supply as it has inherent
self regulation, many even add regulation beyond that, on the other hand, the
designer may feel there is an advantage to allowing the voltage supply to
fluctuate with current load, or perhaps didn't consider the regulation at
all..
> think about the idea that 90% of the world believes all stereo's sound the
> same... and 9% reads stereophile... we are less than 1% who shun all of
> that... yet ironically use the same arguments against each other that they
> use against us.
>
Again, this refers to those who learned what they know from marketing
departments (trade publications and reviews) not those who investigate things
scientifically and/or base there opinion on what they hear.
> i kinda think if we cannot measure what we like in a system (yet)... then
> outside of the basic functionality test equipment and science just point us
> in a direction, and our ears must be the guide. even in the most simple
> amp the possiblities are endless... none of this happens in perfect
> vaccuum... but i must admit 10 -6 torr is a good starting point
>
> how bizarre
>
> dave
>
Again, one should not be under the false impression that the measurement
systems used in publications reflect the state of the art in measurement
systems available for research.Download a demo copy of Hyperception Ride for
example if you have any doubt, with that system, one can construct tests that
use music or anything else as a test signal and compare the input and output to
give any information you ask for, it is VERY powerful (and of course, is not
used in publications).
What is very lacking and confusing the design issue is a quantifying of what
aberrations in performance are pleasing to the ear and those that are not (for
example even harmonics added to music sound nice, odd ones don't).
This makes design more difficult as an amplifier that has NO non linearity
under any musical conditions driving real loudspeakers, won't sound as good as
one with pleasing aberrations.
I'm still not sure that the NO non linearity case is not the better design,
personally, I don't like the idea of "special effects", pleasing or not, that
can't be bypassed if desired.
Tom Danley
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: Ultrapath AMP
Date: Mon, 14 Sep 1998 20:09:05 GMT
Source: Sound Digest Archive v01.n423
On Sat, 12 Sep 1998 21:06:46 -0700 (PDT), dslagle@earthlink.net (Dave
Slagle) wrote:
>in the circuit referenced there is a 100 ohm resistor in place... but this
>topology in general is not a source of hum...
Oh. Now I see, having downloaded Dave's version of the schematic from
his web site. But the resitor is pencilled-in.
A copy of the same schematic that I received via fax from Jack at
Electra-Print, last February, lacks the 100-ohm resistor, hence my
assertion that it didn't exist....
- --dnb
=========================================================================
From: Thomas Danley <Tom@ppci.com>
Subject: Re: Ultrapath AMP/Hyperception
Date: Mon, 14 Sep 1998 14:40:31 -0500
Source: Sound Digest Archive v01.n423
HppyEndng@aol.com wrote:
> In a message dated 9/14/98 12:12:22 PM Mountain Daylight Time, Tom@ppci.com
> writes:
>
> << Again, one should not be under the false impression that the measurement
> systems used in publications reflect the state of the art in measurement
> systems available for research.Download a demo copy of Hyperception Ride for
> example if you have any doubt, with that system, one can construct tests that
> use music or anything else as a test signal and compare the input and output
> to
> give any information you ask for, it is VERY powerful (and of course, is not
> used in publications). >>
> Tom,
> Could you tell me (us) where to download a copy of the
> "Hyperception Ride".
> Thanks in advance...
> Dennis Hardesty
Hi Dennis
Sure, go to http://hyperception.com/j98htm/demo.htm
The one you want is called Ride, they also do have virtual instrumentation
packages.
Understand that this is not exactly a measurment system but rather a large set of
DSP function blocks which YOU connect together to form anything you wish, As a
result one can construct essentially any test you can think of (I have about 90%
of a TDS system mapped out).
In addition to testing one can do real time DSP processing as well, such as
simulating room acoustics, creating special effects again, about anything you can
dream of.
The demo has a small number of function blocks but the real thing has something
like 370 or so.
The system will do some things with a good sound card but works best with a DSP
card, the one I have is a 4 ch in, 4 ch out 16 bits, up to 100KHZ sampling rate
but there are a number of cards that are much better. I got mine to augment the
TEF machine for measuring the acoustics in the Great Pyramid in Egypt for a TV
documentary about 2 years ago.
Best Regards,
Tom
=========================================================================
From: "Chris Beck" <cbeck@brewercompany.com>
Subject: Ultrapath preamp
Date: Thu, 10 Sep 1998 12:55:39 -0500
Source: Sound Digest Archive v01.n420
Ok, gang.
Talked to Jack at Electra-Print over lunch regarding my preamp. He
mentioned a few things that I should look into. First, he thought my
filament supply was suspect. Also, he felt that grounding was indeed most
likely the culprit. Those are the two areas I will conquer.
Regarding the cap between the B+ and cathode. This is the essence of the
Ultrapath. He said this is how it works: All transformers need a return
path for the AC signal component on the primary. Where does this go? Back
through the power supply to the last cap, where it's shunted to ground.
Then, this signal comes all the way back to the cathode of the tube through
what? Another big capacitor. The cap in this circuit neatly sidesteps
going through 2 separate capacitors that may even be electrolytic (yuck).
It is an old Western Electric trick. I thought that was pretty slick.
He also expressed concern over the 500K pot. Not for the hum, but for the
HF rolloff the series resistance to the grid combined with Miller
capacitance will cause. Makes sense. Said to get a follower on that phono
stage! Well, first things first, I guess. Damn, gotta make more holes!
:-)
Chris Beck
See my web page at: http://www.execpc.com/~n9zes/index.htm
=========================================================================
From: "Bill Gaw" <whg@tiac.net>
Subject: Re: Ultrapath preamp
Date: Fri, 11 Sep 1998 08:18:13 -0400
Source: Sound Digest Archive v01.n420
If this is Jack Eliano's transformer output preamp circuit, I had one of his
original trial units for evaluation about 6 months ago, and found it to be a
wonderful unit. I and clark Johnsen put it up against multiple megabucks
preamps and it beat them all for acting as close to a strasight wirev with
gain. It was slightly weak in the deep bass, but Jacksaid that was due to
the transformer he had used. I highly recommend that others try this
circuit. Bill
- -----Original Message-----
From: Chris Beck <cbeck@brewercompany.com>
To: Sound Practices List <sound@lists.io.com>
Date: Thursday, September 10, 1998 2:48 PM
Subject: Ultrapath preamp
>Ok, gang.
>
>Talked to Jack at Electra-Print over lunch regarding my preamp. He
>mentioned a few things that I should look into. First, he thought my
>filament supply was suspect. Also, he felt that grounding was indeed most
>likely the culprit. Those are the two areas I will conquer.
>
>Regarding the cap between the B+ and cathode. This is the essence of the
>Ultrapath. He said this is how it works: All transformers need a return
>path for the AC signal component on the primary. Where does this go? Back
>through the power supply to the last cap, where it's shunted to ground.
>Then, this signal comes all the way back to the cathode of the tube through
>what? Another big capacitor. The cap in this circuit neatly sidesteps
>going through 2 separate capacitors that may even be electrolytic (yuck).
>It is an old Western Electric trick. I thought that was pretty slick.
>
>He also expressed concern over the 500K pot. Not for the hum, but for the
>HF rolloff the series resistance to the grid combined with Miller
>capacitance will cause. Makes sense. Said to get a follower on that phono
>stage! Well, first things first, I guess. Damn, gotta make more holes!
>:-)
>
>
>Chris Beck
>
>See my web page at: http://www.execpc.com/~n9zes/index.htm
>
=========================================================================
From: Paul Joppa <pdj@ISDNseattle.net>
Subject: Re: Ultrapath preamp
Date: Fri, 11 Sep 1998 09:25:14 -0700
Source: Sound Digest Archive v01.n420
Simon Busbridge wrote:
>...snip... in a preamp
> the secondary of the transformers are lightly loaded, right? That must
> mean that the majority of the primary current is magnetisation current,
> not load current. Effectively the transformers place a large inductance
> in the anode of the valves. This means that the valves operate under
> constant current conditions, with the AC current in the anode circuit
> being zero. So cathode bypass caps, ultrapath caps actually have no
> effect in such a circuit!
Correct in the limit (at infinite frequency with perfect components).
But it's important to remember that large is not infinite, nor is
small zero. The AC current in the anode is the sum of the load current
(small but non-zero) and the magnetization current (small except at
low frequencies). The bypass and/or ultrapath (and/or power supply!)
caps must have impedances small enough to absorb this current. At low
frequencies, the magnetization current is not small, so the caps need
to be large enough to obtain adequate bass.
- -Paul Joppa
=========================================================================
From: Simon Busbridge <S.C.Busbridge@bton.ac.uk>
Subject: Re: Ultrapath preamp
Date: Fri, 11 Sep 1998 09:32:59 +0100 (BST)
Source: Sound Digest Archive v01.n420
>Regarding the cap between the B+ and cathode. This is the essence of the
>Ultrapath. He said this is how it works: All transformers need a return
>path for the AC signal component on the primary. Where does this go?
>Back through the power supply to the last cap, where it's shunted to
>ground. Then, this signal comes all the way back to the cathode of the
>tube through what? Another big capacitor. The cap in this circuit
>neatly sidesteps going through 2 separate capacitors that may even be
>electrolytic (yuck). It is an old Western Electric trick. I thought that
>was pretty slick.
Ah! I see!
I hope this doesn't sound dumb, or put a damper on things, but in a preamp
the secondary of the transformers are lightly loaded, right? That must
mean that the majority of the primary current is magnetisation current,
not load current. Effectively the transformers place a large inductance
in the anode of the valves. This means that the valves operate under
constant current conditions, with the AC current in the anode circuit
being zero. So cathode bypass caps, ultrapath caps actually have no
effect in such a circuit!
This is of course different to a SE power amp, where load current appears
in the primary (anode) circuit. Without knowing the history, I suspect
WE used it in this type of amplifier.
Have I got that right?
Simon
Dr Simon Busbridge
Department of Mechanical and Manufacturing Engineering
University of Brighton
Lewes Road
Moulsecoomb
Brighton BN2 4GJ
UNITED KINGDOM
Tel: 0044 (0)1273 642542
Fax: 0044 (0)1273 642327
e-mail: s.c.busbridge@bton.ac.uk, scbusbridge@hotmail.com
=========================================================================
From: RALPH POWER <POWER.RALPH@epamail.epa.gov>
Subject: Ultra path -Reply
Date: Wed, 16 Sep 1998 11:03:06 -0400
Source: Sound Digest Archive v01.n424
Hi Larry,
I too tried the Ultrapath mod over the weekend, but on the OUTPUT stage of
my 6B4G amp. I used two 22uf Solens to connect the B+ and the wiper of my
humpots. I left the 6B4G cathode resistors and bypass caps in place BTW.
The sound was somewhat similar to my fixed bias experiments of the previous
weekend, giving most of the good points, tighter focus, deeper soundstage,
with detail and delicacy galore. But, unlike the fixed bias sound I got, it didn't
remove most of the body, color, and immediacy to the sound, only a portion
of it. Different perspective for sure.
I could see this being desirable in the right system or with some more tweaking.
If one could get the best of both worlds, you would really have something there
I think. But Sunday night I removed the mod to get back to the richer, more
colorful sound with more body, as I am hooked on this sound at least for now.
I may try the mod again on the input stage and with smaller Hovlands to see what
happens then. There is something going on here for sure.
My 2 cents,
- Ralph
=========================================================================
From: "Frank Deutschmann" <fdeutsch@bfm.com>
Subject: Uncle Sam's tube stash
Date: Wed, 10 Sep 1997 16:58:29 -0400
Source: Sound Digest Archive v01.n019
Today, bumbling about the web, I happened to come across Uncle Sam's very own
tube stash, and he's definitely holding! Better yet, he's dealing! Check out:
http://www.drms.dla.mil/
(Hint: search with the term "electron tube")
Now, this database is pretty hard to search and there's lots of irrelevant
junk, but there are some real finds. Unfortunately, though it seems to be all
via sealed bid, and in rather huge quantities. But if someone is interested in
doing a joint bid, I'd be game....
- -frank
=========================================================================
From: BART <bartonw@ozemail.com.au>
Subject: RE: Uncle Sam's tube stash
Date: Thu, 11 Sep 1997 15:36:06 +1000
Source: Sound Digest Archive v01.n019
Frank,
Why dont we setup a list of available tubes of interest with probably
pricing on this list and accumulate requests for a bulk buy between us all?
Count me in on this.
We could add to pretty respectable quantities between us all.
Would you care to hold the money and make the bid on our behalf?
Bart
- ----------
From: Frank Deutschmann[SMTP:fdeutsch@bfm.com]
Sent: Thursday, 11 September 1997 6:58
To: sound@lists.io.com
Subject: Uncle Sam's tube stash
Today, bumbling about the web, I happened to come across Uncle Sam's very
own
tube stash, and he's definitely holding! Better yet, he's dealing! Check
out:
http://www.drms.dla.mil/
(Hint: search with the term "electron tube")
Now, this database is pretty hard to search and there's lots of irrelevant
junk, but there are some real finds. Unfortunately, though it seems to be
all
via sealed bid, and in rather huge quantities. But if someone is
interested in
doing a joint bid, I'd be game....
- -frank
=========================================================================
From: David Bardes <David_Bardes@zd.com>
Subject: RE: Uncle Sam's tube stash
Date: Thu, 11 Sep 1997 09:26:15 -0800
Source: Sound Digest Archive v01.n020
Has anyone spent the time to go through each listing on this site to
decipher what and how many tubes each listing contains?
I spent a few minutes on the site yesterday. A random sampling showed some
pretty exotic tubes (as in I can't imagine it could be used for audio), a
lot of one-of-a kind stuff, and cathode ray tubes (TV/Radar/computer
screens). It seems like it would take several hours to go through the list
and find out what's available.
Maybe some direct help from the DRMS would enable us to compile a better
list of what is available.
David
=========================================================================
From: Richard C Nevill <rnevill@is.dal.ca>
Subject: RE: Uncle Sam's tube stash
Date: Thu, 11 Sep 1997 11:14:44 -0300 (ADT)
Source: Sound Digest Archive v01.n020
I like this idea
Richard Nevill
On Thu, 11 Sep 1997, BART wrote:
>
> Frank,
>
> Why dont we setup a list of available tubes of interest with probably
> pricing on this list and accumulate requests for a bulk buy between us all?
>
> Count me in on this.
>
> We could add to pretty respectable quantities between us all.
>
> Would you care to hold the money and make the bid on our behalf?
>
> Bart
>
> ----------
> From: Frank Deutschmann[SMTP:fdeutsch@bfm.com]
> Sent: Thursday, 11 September 1997 6:58
> To: sound@lists.io.com
> Subject: Uncle Sam's tube stash
>
>
> Today, bumbling about the web, I happened to come across Uncle Sam's very
> own
> tube stash, and he's definitely holding! Better yet, he's dealing! Check
> out:
>
> http://www.drms.dla.mil/
>
> (Hint: search with the term "electron tube")
>
> Now, this database is pretty hard to search and there's lots of irrelevant
> junk, but there are some real finds. Unfortunately, though it seems to be
> all
> via sealed bid, and in rather huge quantities. But if someone is
> interested in
> doing a joint bid, I'd be game....
>
> -frank
>
>
>
=========================================================================
From: alan cameron <alan@thehub.com.au>
Subject: RE: Uncle Sam's tube stash
Date: Fri, 12 Sep 1997 12:28:31 +1000
Source: Sound Digest Archive v01.n020
Also sprach David Bardes, aus 11/9/97:
> Has anyone spent the time to go through each listing on this site to
> decipher what and how many tubes each listing contains?
>
> I spent a few minutes on the site yesterday. A random sampling showed some
> pretty exotic tubes (as in I can't imagine it could be used for audio), a
> lot of one-of-a kind stuff, and cathode ray tubes (TV/Radar/computer
> screens). It seems like it would take several hours to go through the list
> and find out what's available.
>
> Maybe some direct help from the DRMS would enable us to compile a better
> list of what is available.
>
> David
I came across an F-16, as in aircraft. In the 'electron tube' list. More
than one in stock, I believe.
alan
=========================================================================
From: Stewart Ferrell <sferrell@pfmc.net>
Subject: Re: Uncle Sam's tube stash
Date: Fri, 12 Sep 1997 08:25:59 -0400
Source: Sound Digest Archive v01.n021
alan cameron wrote:
> Also sprach David Bardes, aus 11/9/97:
>
> > Has anyone spent the time to go through each listing on this site to
>
> > decipher what and how many tubes each listing contains?
> >
> > I spent a few minutes on the site yesterday. A random sampling
> showed some
> > pretty exotic tubes (as in I can't imagine it could be used for
> audio), a
> > lot of one-of-a kind stuff, and cathode ray tubes (TV/Radar/computer
>
> > screens). It seems like it would take several hours to go through
> the list
> > and find out what's available.
> >
> > Maybe some direct help from the DRMS would enable us to compile a
> better
> > list of what is available.
> >
> > David
I'm thinking about giving up HIFI and collecting and restoring
locomotives.
>
>
> I came across an F-16, as in aircraft. In the 'electron tube' list.
> More
> than one in stock, I believe.
> alan
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: RE: Uncle Sam's tube stash
Date: Fri, 12 Sep 1997 09:17:30 +0200 (MET DST)
Source: Sound Digest Archive v01.n021
At 09:26 11/09/1997 -0800, David wrote:
>Has anyone spent the time to go through each listing on this site to
>decipher what and how many tubes each listing contains?
>I spent a few minutes on the site yesterday. A random sampling showed some
>pretty exotic tubes (as in I can't imagine it could be used for audio), a
>lot of one-of-a kind stuff, and cathode ray tubes (TV/Radar/computer
>screens). It seems like it would take several hours to go through the list
>and find out what's available.
Hello,
Here are few more items from the list:
- -----------------------------------------------
reference model Qty.
- ------------------------------------------------
5960007854255 12B4A 9
5960005430009 12AV7
5960001883551 6AK6
5960001078147 829B
5960001005268 6SJ7Y 9 (metal envelop.)
5960001144868 807 17
5960008401055 7609
5960001346031 5654W
5960006809689 6197 2264
5960009527202 7788 7
5960002305228 5639
5960007613833 8116
- -----------------------------------------------
Best regards,
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: "Le Cleac'h J.-M." <lecleach@cgi.ensmp.fr>
Subject: RE: Uncle Sam's tube stash
Date: Fri, 12 Sep 1997 14:12:18 +0200 (MET DST)
Source: Sound Digest Archive v01.n021
At 04:26 12/09/1997 -0400, you wrote:
>Could somebody please tell me again where I can find this list?
>Many thanks
>Holger Stein
Try:
http://www.drms.dla.mil/htbin/public2.sh?Name=electron+tube&Date=&PIStatus=A
&S1=Z1&S2=Z2&S3=Z3&S4=Z4&S5=Z5&S6=Z6&S7=Z7&S8=Z8&S9=Z9&S10=Z10&S11=Z11&S12=Z
12&S13=Z13&S14=Z14
Best regards
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: AnnaLogg@aol.com
Subject: uncLogged at last. . . (heheheh. . .)
Date: Fri, 2 Oct 1998 09:36:44 EDT
Source: Sound Digest Archive v01.n436
Sorry about the deluge of uncLogged ;-) repetitious posts!
Well, I just got stubborn, is all . . . (I figure the last copy I sent pushed
the first one into the queue? Finally? ;-D)
Anyway, you'll all be glad to know that's probably it for a while until
somebody talks about music and/or sound again. (fair warning ;-)
Best, as usual,
Anna
=========================================================================
From: NonDelivery MailManager-MDIL02N1 <NonDelivery_MailManager-MDIL02N1@email.mot.com>
Subject: Undeliverable Mail
Date: Sat, 30 Aug 1997 20:02:04 -0500
Source: Sound Digest Archive v01.n007
Message: Re: Learner designer - VT-52 amp
Sent: Sat, Aug 30, 1997 8:49 AM
To: Box-EAB008 Ashby
On Server: FL08_MS_Mail_13
Date: Sat, Aug 30, 1997 8:57 PM
Reason: Could not be delivered because the destination Microsoft Mail server
could not be found.
=========================================================================
From: NonDelivery MailManager-MDIL02N1 <NonDelivery_MailManager-MDIL02N1@email.mot.com>
Subject: Undeliverable Mail
Date: Sun, 31 Aug 1997 1:16:44 -0500
Source: Sound Digest Archive v01.n007
Message: VT-24 problem. Please help
Sent: Sat, Aug 30, 1997 2:10 PM
To: Box-EAB008 Ashby
On Server: FL08_MS_Mail_13
Date: Sun, Aug 31, 1997 2:14 AM
Reason: Could not be delivered because the destination Microsoft Mail server
could not be found.
=========================================================================
From: "Thorsten \"EZEE\" Loesch" <tloesh_2@globalnet.co.uk>
Subject: Unhappy Balls and Spikes :-)
Date: Tue, 9 Sep 1997 22:38:21 +0100
Source: Sound Digest Archive v01.n018
Dave,
> Thanks for the modification idea, I will employ it on my 63SE. An
> alternative to the spikes is Norsorex spheres al a Audioprizms
Isoshperes.
> Edmund Scientific has these as part of a experimenters pack labeled
"Happy
> and Unhappy Balls" . For $5 US, these come with one regular "super ball"
> (happy ball) and one Norsorex ball (unhappy ball) perfect for use as
feet.
> To keep these from rolling around, I used metal washers available from
any
> hardware store to set them in. It's a nice tweak for CD players,
turntables
> and even VCRs.
Very nice Idea. The REGA Planet uses something like that. Well my HiFi-
Rack has a lot of polished Brass and high-gloss black, so I thought they
lookd nice and they do the Job.
These "Spike-Dampers" (Goldring Speak) have two Sorbothane inserts
and two metal-parts.One Sorbothane Insert is the Surface I glued to the
CD-Player. That Cotacts to a Brass Disk, which contacts to another
sorbothane insert, which in turn contacts to a Cone with a removable /
levelable stainless Steel Insert. This in turn sits in a Brass Cup.
This whole contraption then sits on top of my home-made Air isolation /
constrained layer damping Platform.
Absolute overkill I know. But it is relativly cheap and works.
Kind regards Thorsten.
======================================
e-mail:
Torsten.Loesch@enhar-ha.nthames.nhs.uk
Disclaimer: The opinions expressed herin
are my personal ones and do not in any
way reflect opinions or policies of my
employer.
web-pages:
http://www.users.globalnet.co.uk/~tloesh_2
======================================
=========================================================================
From: "Bastien Bouchard" <bastienb@microtec.net>
Subject: United Electronics 845 W
Date: Tue, 25 Nov 1997 15:51:16 -0500
Source: Sound Digest Archive v01.n119
Hello all,
I would like to know more about this tube. Someone here have some to sell
but for big $$$... So, i wonder if it is similar to the RCA in term of
ratings and value. Maybe i would take the plunge in a big bad amp
project...
Thanks,
Bastien
=========================================================================
From: Jeroen Euwe <jeroen.euwe@let.ruu.nl>
Subject: Re: United Electronics 845 W
Date: Tue, 25 Nov 1997 22:37:36 +0000
Source: Sound Digest Archive v01.n119
Bastien,
According to an article by Jean Hiraga in L'Audiophile (jan '95), the
following are equivalents or very close versions:
C-845
DR-845
GL 845
T-845
JE-845
WL-845
945
JAN-845W
845W
T-110-1
WE 284D
THey were made by: Brown Boveri, Cetron, Delco Radio Division, Eimac,
General Electric, Golden Dragon, RCA, Sungrill, Taylor, Toshiba,
Unted Electronic, Westinhouse (should probably be Westinghouse),
Western Electric.
I realise this doesn't answer your question fully, but I've
personally only seen the Chinese one.
Jeroen
> Hello all,
>
> I would like to know more about this tube. Someone here have some to sell
> but for big $$$... So, i wonder if it is similar to the RCA in term of
> ratings and value. Maybe i would take the plunge in a big bad amp
> project...
>
> Thanks,
>
> Bastien
>
>
=========================================================================
From: slagle@dtlweb.com (Dave Slagle)
Subject: universal refinements....
Date: Wed, 12 Nov 1997 18:28:16 -0500 (EST)
Source: Sound Digest Archive v01.n106
hey,
been doing some listening lately and the prospect of a chassis is on the
horizon.
the current thinking on the basic topology has changed a bit, still want to
make it a universal design that can accept any 4 pin tube, and make the
operating points adjustable by a variac, but want to offer a purist mode in
which the variacs are bypassed... since they do seem to degrade the sound,
oh well you can't have it all...
One thing I have come across though is that 45's and 300B's can operate
pretty happily in the same design, and with a minimum of fuss an amp can be
designed to easily work with both...
all that is needed is a power trannie that has a split primary, and
standard parallel (115) connection will provide a B+ for the 300B... say
500V take away your 85V bias gives you 415V @ 80ma with a 950 ohm or so
resistor and you get a nice oerating point....
now with the flick of a switch you can series the primary windings for 1/2
voltage operation (if your trannie has a 5V winding this may even give you
the proper filament voltage??) of course other filament windings will have
to be considered, but even if you use separate 5V trannies, a
series/parallel configuration can solve the 2.5/5V dilemma.
anyways with a 250V B+ and a 950 ohm resistor a 45 (or at least the ones I
have) will bias out at about -35V which gives me a B+ of 215V and 40ma of
current, which is IMO a killer operating point for this tube... yeah you
only get about a watt or soo, but for low level listening and efficient
speakers, its plenty!
The beauty of this is you get the best of both worlds.... you get all of
the refinement and low level detail that the 45 is known for, and when it
is time to rock... or piss off your neighbors... help is only a flick of a
switch and swap of a tube away...
Over the past few weeks have come to the conclusion, that a 45-300B amp is
the ideal thing for me.. I have 2A3's and they are OK... they sorta fall
right in the middle of the group for me... they play louder than the 45's
(specially if ya beat the hell out of the chinese ones) and sound better at
low levels than the 300B, but once you go up a bit the 300B brings out the
fun, so my feelings are why bother with the middle.. go for the extremes...
One thing about this type of setup is the setting of a nice operating
point... with proper part selection, a pair of 45's and 300B's can be
optimised... but the finding of the proper combo of B+ and cathode resistor
always seems to be a compromise... so I am thinking start with a chosen B+
and a standard 1K cathode resistor.... then take a 6 pole switch with
various resstors to parallel with the 1K to adjust the cathode resistor
from say 1K down in your desired incraments to allow for adjustment of your
operating point....
nah it'll never sound good...
dave
=========================================================================
From: John Levreault <jlevro@shore.net>
Subject: Re: universal refinements....
Date: Thu, 13 Nov 1997 09:10:23 -0500
Source: Sound Digest Archive v01.n107
At 06:28 PM 11/12/97 -0500, Dave Slagle wrote:
<...about a universal amp....>
Hi, Dave.
FWIW, here's what I do that accomplishes your goal but with a bit more work.
I use a Hammond 400V/200ma power tranny with the usual 5V filament winding
which I use for the rectifier (5R4GYB these days), and 6.3VAC, which I
rectify/filter for the low level tube, the 3A/167M most recently.
The basic wiring is for 300B: I run the power supply C-L-C with a 10uf
Solen/10H/100uf Cerafine. This gives me about +450 on the plate. I use a 1K
cathode R bypassed with 100uf, giving about 72ma of plate current. I
install a 5VAC filament tranny and use a tapped resistor pair across the
filament for hum reduction, instead of a pot. I also have a power supply
R-C for the driver stage. I run the 3A/167M at 10ma with a choke load, so I
use a 22K resistor to another 100uf Cerafine, and I end up with about 220V
on the plate of the 3A/167M.
To convert to 2A3, I first lift the 10uf Solen, converting the ps to L-C.
This drops the B+ to about +330. Hum is not a problem. Next, I replace the
filament tranny with a 2.5V'er. I then add a 7.5K/3W resistor in parallel
with the 1K cathode R and get about 60ma of plate current with a net +270
across the tube, a bit hotter than some suggest, but I've had no problems.
Then I remove the 22K dropping resistor for the driver and replace it with
a 6.2K, restoring the +220 on the driver.
To convert this to 45, I remove the 7.5K shunt on the cathode R, lift the +
lead of the cathode bypass cap off the resistor, and add about 440 ohms in
series with the 1K and reinstall the bypass. Operating point is now about
+275/36ma, just like the book sez.
Conversion from 300B to 2A3 takes about 45 minutes, including test to make
sure I didn't screw anything up. Conversion from 2A3 to 45 takes all of 10
minutes. I generally do the cycle every few months, 300B to 2A3 to 45 to
2A3 to 300B. I get stuck on the 2A3 for 90% of the time.
You might ask what I do about the output tranny: nothing. I use an FS030.
My speakers have a fairly flat impedance of around 6 ohms. The presents a
nominal 4.5K to the tube, which is higher than one normally sees for either
the 300B or 2A3, but sounds great to me. (I do not wish to stir up the
"load impedance wars" of a few months ago, but then again this list is
getting much too "nice" these days ;-)) Interestingly, this 4.5K is just
about right for the 45, according to the book. Remember that with a highish
load impedance, you sacrifice power for distortion. I still get ~8W from a
300B, ~4W from a 2A3, and about 2.6W from a 45 into 6 ohms, all at the 5%
distortion point.
>
>Over the past few weeks have come to the conclusion, that a 45-300B amp is
>the ideal thing for me.. I have 2A3's and they are OK... they sorta fall
>right in the middle of the group for me... they play louder than the 45's
>(specially if ya beat the hell out of the chinese ones) and sound better at
>low levels than the 300B, but once you go up a bit the 300B brings out the
>fun, so my feelings are why bother with the middle.. go for the extremes...
>
>
I agree with your assessment of the individual tubes, which is why I like
the 2A3. I get most of the low level beauty of the 45 with most of the
power of the 300B, but that's just the way I am.
John Levreault
=========================================================================
From: slagle@dtlweb.com (Dave Slagle)
Subject: Re: universal refinements....
Date: Thu, 13 Nov 1997 11:39:47 -0500 (EST)
Source: Sound Digest Archive v01.n108
bob d. sed..
>that angela universal 760VCT pt has dual secondaries.
>would give you just about 500V after an 83 and filter.
>haven't seen any other pt's with split primaries.
>maybe special order from hammond...
Look for military surplus... I paid $12 a pop for mine, can't beat that
with a stick!! and dunker factor to boot!
>you'd need a separate 5V tranny for the rectifier, though.
>but don't you pre-heat the 83 filaments, anyway ?
>you could also consider ss rectification...
bite your tongue! anyways where the hell am I supposed to get a hexfred
this time of the night??
>yeah, like sticking the 2a3 into the amp optimised for the 45.
>in my amp they bias up identically (50V cathode bias)
>but the 2a3 OP is not as good as it could be...
I have found that 2A3's will generally bias up the same as 45's do...(that
is a 45 biased at 10W of plate diss will yeild a 2A3 biased up at 15W, but
in both your case and mine, the operating point is not ideal.... I hear the
2A3 like the 300B wants to be run high current AND high voltage.
>btw: your OP for the 45 is definitely sweet. i'm pretty sure
>that my dissappointment (a very relative term) with my current
>45 amp is related to a higher B+. looking for a simple fix
>which won't screw up the 2a3 option...
the 235v B+ 42ma operating point for the 45 will run a 2A3 at 220v and 72
ma or so....
>i can get the B+ up a little (better for the 2a3) and DC couple
>the 45!?!
thats a cool solution...
>i'm trying to avoid a large dropping resistor in the B+
>(although it's easy enough to try..
or how about just a large cathode R and forget about the direct
coupling.... talk about easy, and I for one would be interested in hearing
the results of a large dropping R vs. a large cathode R to solve an
overvoltage situation...
hell maybe the cathode resistor could set your operating point from a
single fixed B+??? I know people complain about large cathde r's, but they
complain about 83's and IT's too...
<snip>
john mumbled:
>You might ask what I do about the output tranny: nothing.
good!
>sounds great to me.
good
> (I do not wish to stir up the
>"load impedance wars" of a few months ago, but then again this list is
>getting much too "nice" these days ;-))
Stir away 3A167mboy just once I would like to see the whole tap swapping
thing done from a listening point of view... (or the 300B operating point
for that matter) no science allowed... it seems the minute science gets
involved the smartest person wins.. case closed... but if we talk listening
impressions suddenly the playing field is even. no correct or incorrect...
just opinions... and then its the way it should be.... the loudest person
wins.
dave
=========================================================================
From: Bob Danielak <rdaniela@ew.lmms.lmco.com>
Subject: Re: universal refinements....
Date: Thu, 13 Nov 1997 18:32:32 -0500
Source: Sound Digest Archive v01.n108
Dave Slagle wrote:
>
> bob d. sed..
> >that angela universal 760VCT pt has dual secondaries.
> >would give you just about 500V after an 83 and filter.
>
> >haven't seen any other pt's with split primaries.
> >maybe special order from hammond...
>
> Look for military surplus... I paid $12 a pop for mine, can't beat that
> with a stick!! and dunker factor to boot!
>
reveal your source. we know where you live.
we require the information....
> >you'd need a separate 5V tranny for the rectifier, though.
> >but don't you pre-heat the 83 filaments, anyway ?
> >you could also consider ss rectification...
>
> bite your tongue! anyways where the hell am I supposed to get a hexfred
> this time of the night??
>
> >yeah, like sticking the 2a3 into the amp optimised for the 45.
> >in my amp they bias up identically (50V cathode bias)
> >but the 2a3 OP is not as good as it could be...
>
> I have found that 2A3's will generally bias up the same as 45's do...(that
> is a 45 biased at 10W of plate diss will yeild a 2A3 biased up at 15W, but
> in both your case and mine, the operating point is not ideal.... I hear the
> 2A3 like the 300B wants to be run high current AND high voltage.
>
yeah, the 2a3 looks better on paper back 'round 250V or less
and higher current. but i found that it sounded better at about
280V and relatively high current ('bout 17.5W plate diss, if i remember
correctly).
btw: this was in a DC coupled amp that was supposed to take
a 300B ac coupled - an early attempt at an universal amp...
that's what made me think of the solution below...
> >btw: your OP for the 45 is definitely sweet. i'm pretty sure
> >that my dissappointment (a very relative term) with my current
> >45 amp is related to a higher B+. looking for a simple fix
> >which won't screw up the 2a3 option...
>
> the 235v B+ 42ma operating point for the 45 will run a 2A3 at 220v and 72
> ma or so....
>
> >i can get the B+ up a little (better for the 2a3) and DC couple
> >the 45!?!
>
> thats a cool solution...
>
> >i'm trying to avoid a large dropping resistor in the B+
> >(although it's easy enough to try..
>
> or how about just a large cathode R and forget about the direct
> coupling.... talk about easy, and I for one would be interested in hearing
> the results of a large dropping R vs. a large cathode R to solve an
> overvoltage situation...
>
> hell maybe the cathode resistor could set your operating point from a
> single fixed B+??? I know people complain about large cathde r's, but they
> complain about 83's and IT's too...
>
well, i don't know how well this would work without direct coupling.
it's obviously not as easy as swapping the cathode resistor
(since this determines your bias). you'd have to tap the resistor and
reference your grid resistor to retain the proper bias. then you'd
have to decouple the added resistor.
the equivalent circuit is pretty much the same as the resistor in the
supply lead, i think...
one benefit might be that this bypass cap wouldn't have to be rated
for the full B+....
i'm thinking that a single cap from cathode to ground isn't enough
because the mid tap is connected to ac ground thru the parallel
combination of the two cathode resistors. but maybe it doesn't
have to be connected directly to ground.
sure! when you consider the normal size of the grid resistor
(100k's) versus the "extra" cathode contribution of 100's of ohms...
so long as the single bypas cap does a good job of keeping ac out
of the resistors, you won't have any degeneration to worry about...
you can see that i'm mulling this one over as i go along, but
f**kin' brilliant, again. i think?
worth a bit more thought
and maybe a try this weekend.
> <snip>
>
bob.d.
=========================================================================
From: Plaato@aol.com
Subject: Re: Re: universal refinements....
Date: Thu, 13 Nov 1997 23:13:22 -0500 (EST)
Source: Sound Digest Archive v01.n108
Hi, John and Steve,
I've been developing a multi output tube amp myself for the past few years.
It is truly a work in progress in that it never stays the same for more than
a few weeks, but I can run 2A3, 45, 300B, 275A, VT52, VT25 , ,10's and what
have you. The power supply is 83 or 5Z3 (to drop a few volts ) CLC
25uf-10H-25uf but I can switch in a low DCR 6Henry Choke for Choke input and
drop even a few more volts. The power supplies are dual mono on one chassis
using Hammond 400-0-400 125 ma power trans. The filament arrangement is a
switch that selects either a 2.5 volt fil trans or a 6.3 volt 2A trans. If I
want to drop Fil. voltage down to 5 Volts I can switch in a series Resistor
on the 6.3 volt setting, so I have switchable filament voltages of 2.5, 5 and
6.3 volts. One person I know (Joe Lowe) I think uses a big pot in the primary
of the Filament trans to adjust voltage. (Care to comment, Joe?)
The amp itself, well, lately it's been 5842 IT coupled to whatever output
tube. Right now I'm using the cheapo AES route and am looking at various
better but affordable IT options. Any suggestions? The AES unit works
surprisingly well. I'm parafeeding the primary of the IT with 50H plate load
on the 5842 and 2 mfd, The 5842 has nicad bias.
The output stage is biased with a big adjustable 5000 ohm power resistor.
Current and Plate voltage are metered. The output stage is parafeed also,
using Mikes 50H 60ma chokes and 4mfd 1kv sangamo oils. The opts are small
mystery units in grey octoganal cans with multi tapped primaries of 2.5, 4,
7.5 and 10K and the usual secondaries.
To switch output tubes I use the following settings:
45,2A3 and 275A- use 5Z3 rectifier, switch in choke input power supply and
adjust bias for individual tubes. OPT primaries are also switchable.
for 300B,10,VT52, use 83 rectifier, switch out the ps input choke and adjust
bias and load resistance.
I could go on a long rant about the sound of these various tubes, but I'll
spare you. Suffice it to say that my favorite all around tubes are the 45
and VT52. (I listen to big horn speaks). I like 2A3's too, 300B's give a
bigger sound and 10's really surprised me with their get up and go. Hum is a
problem only with the 300B.
The 275A ia a really interesting tube. Sort of halfway between a 2A3 and a
45. They seem to like 45ish operating points better, ie: about 4K load
resistance biased at about 40ma. I'd really like to try some 50's. Anybody
got a pair they want to trade for some WE275A's?
That's about all for now.
Henry
=========================================================================
From: slagle@dtlweb.com (Dave Slagle)
Subject: Re: Re: universal refinements....
Date: Fri, 14 Nov 1997 09:56:15 -0500 (EST)
Source: Sound Digest Archive v01.n109
>One person I know (Joe Lowe) I think uses a big pot in the primary
>of the Filament trans to adjust voltage. (Care to comment, Joe?)
well i.m not joe, but i am currently using a pair of cheapo 6.3V @ 1.2A
filament trannies to light my fils.... I wired them so a switch will
either series or parallel the primaries, and a 1.75A panel mount variac
allows for adjustment....
i haven't noticed any diffeence between a 45 wires with the trannies in
series and the variac at 80% as opposed to the parallel connection and the
varic set at 40%... oh yeah... a variac that goes to 132V will also do 7.5V
tubes if you bump the current handling a bit...
taking this a bit farther... you could also apply this to separate power
trannies too, I guess the situation is not ideal for the series connection
since a high current draw in one amp would show up in the other... but we
are class A here.... it'll work in a pinch!
has anybody ever monitored current draw on the input of an amp???
dave
=========================================================================
From: "Smith, Richard Todd" <SmithRT@lci.com>
Subject: University Classic
Date: Fri, 30 Jan 1998 11:18:00 -0500
Source: Sound Digest Archive v01.n176
Hello,
Someone had e-mailed me about having a brochure explaining the
University Classic Horns. I was wondering if there was a problem
sending a copy? Does anyone else have info or spec to biuld these
horns?
=========================================================================
From: "Smith, Richard Todd" <SmithRT@lci.com>
Subject: University compression horns
Date: Mon, 2 Feb 1998 16:16:00 -0500
Source: Sound Digest Archive v01.n179
I found a pair of University horns with compression drivers,
altenuators, etc... at a local pro shop. They said University Sound or
something of that nature and product of Altec corp. I believe they were
model 30465 or something like that. I listened to them and they sounded
like they worked perfect. The price was $80 for the pair. Is this a
good deal?
=========================================================================
From: bill gardner <wg44929@navix.net>
Subject: University compression horns
Date: Mon, 02 Feb 1998 20:31:55 -0600
Source: Sound Digest Archive v01.n180
>From: "Smith, Richard Todd" <SmithRT@lci.com>
>To: "'sound practice's'" <sound@deliverator.io.com>
>Subject: University compression horns
>Date: Mon, 2 Feb 1998 16:16:00 -0500
>Sender: owner-sound@lists.io.com
>
>I found a pair of University horns with compression drivers,
>altenuators, etc... at a local pro shop. They said University Sound or
>something of that nature and product of Altec corp. I believe they were
>model 30465 or something like that. I listened to them and they sounded
>like they worked perfect. The price was $80 for the pair. Is this a
>good deal?
> If you listened and you dug the music ... then its a
deal you can't pass up .... you can always get more money , but fun ...
thats not so easy . Bill Gardner
=========================================================================
From: Miroslav Kubala <100432.144@compuserve.com>
Subject: University/Goodmans/AD1
Date: Sun, 1 Feb 1998 03:16:53 -0500
Source: Sound Digest Archive v01.n178
Hi
can anyone of you help me get University mid-horn drivers?
Just the two biggest models used for the cobraflex-horns.
Buy:
need 1 ( or 2 ) Goodmans triaxiette
and Goodmans Axiom 150
Has anyone a idea how the Mastering Lab Crossover was build ?
Layout,parts? Need it for my Altecs 604 ( see article in VTV,isuue 3,vol.1
)
Sell: AD1 1pair NOS
Telefunken diamond bottom ECC88 and others
Thanx for the bandwide...
Mirko
mikubala@swissonline.ch
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: Re: University Speakers
Date: Wed, 28 Jan 1998 13:18:22 -0800
Source: Sound Digest Archive v01.n174
Smith, Richard Todd wrote:
>
> Has anyone heard of University Drivers (model c15w)? Bruce Edgar, I was
> told used them to make bass horns. Does anyone have any info or a
> design of this horn?
Richard,
The C15W is a moose of a speaker (15 inch) weighing about 30 or 35 lbs
with a humongous alnico magnet. It was used in the University Classic
Folded Horn speaker. I happen to have the original University brochure
describing the enclosure construction with all the dimensions. They
were available in a corner and a side-wall version. As I recall, they
were 40 Hz horns, not a back loaded horn, but a true horn with a sealed
rear compartment. I do not recall having ever heard one. I suspect
that they were mucho efficient though.
There is a chap in the Los Angeles area with a pair of these things
complete with the mid and tweeters. He has been trying to sell them for
$400. The only kicker is that they must be picked up there. Also,
another chap was trying to sell a pair of woofers only on
rec.audio.whatever the other day for something like $300.
I once had a single C15W back in about 1960 that I bought for twenty
bucks. I never mounted it into anything, but istening to it full range,
it was undoubtedly the most wretched sounding speaker I have ever
encountered. I traded it off for a JBL E140 right away. Maybe it is a
fine speaker when loaded in a horn and properly crossed over. As I
recall the Classic crossed over at something like 350 Hz. And that is
the extent of my knowledge, at least on that particular subject.
Dan Marshall
=========================================================================
From: "Smith, Richard Todd" <SmithRT@lci.com>
Subject: University Speakers
Date: Wed, 28 Jan 1998 15:08:00 -0500
Source: Sound Digest Archive v01.n174
Has anyone heard of University Drivers (model c15w)? Bruce Edgar, I was
told used them to make bass horns. Does anyone have any info or a
design of this horn?
=========================================================================
From: Scott Grammer <tubedude@cdc.net>
Subject: Re: Unloaded OTs
Date: Thu, 05 Nov 1998 06:24:18 -0500
Source: Sound Digest Archive v01.n481
Alex Megann wrote:
> (snip)
> What are the long-term consequences of operating a valve
> amplifier with the output transformer unloaded (or nearly
> unloaded), though?
>
> Alex
Alex:
It depends on the design of the amp. If it is conservatively designed,
with the output valves run at less than full tilt, then the damage would
probably manifest itself in the output trannies only, where the voltage
created by the undamped back-emf can puncture the primary insulation. If
the amp is built closer to the limits of the tubes, flashover inside the
tubes can occur, destroying them, the output trannies, and more. It also
depends on the inherent high-frequency stability of the design. Amps
with a lot of negative feedback can oscillate when unloaded, and this
can accellerate the same destruction mentioned earlier.
I have seen smallish P-P amps (12 watts from a pair of EL84's) that were
designed so that when headphones were used a 47 ohm 5 watt resistor was
shunted across the 16 ohm output, providing a minimal load to the amp.
This seemed to work fine.
Hope this helps!
S.G.
- --
Visit TubeDude's Webpage of Vacuum Tube Lore!
http://www.cdc.net/~tubedude
Also check out Smoke Free Youth!
http://www.cdc.net/~tubedude/smokefreeyouth.html
See what I have for sale!
http://members.ebay.com/aboutme/tubedude@cdc.net/
=========================================================================
From: "David B. Klein" <dklein@microtec.net>
Subject: Re: Unloaded OTs
Date: Thu, 5 Nov 1998 06:32:35 -0500 (EST)
Source: Sound Digest Archive v01.n481
At 10:19 AM 11/5/98 GMT, Alex Megann wrote:
>What are the long-term consequences of operating a valve
>amplifier with the output transformer unloaded (or nearly
>unloaded), though?
>
> Alex
Lack of satisfaction with one's loudspeakers?
dbk
=========================================================================
From: "Chris Beck" <cbeck@brewercompany.com>
Subject: Re: Unloaded OTs
Date: Thu, 5 Nov 1998 07:16:21 -0600
Source: Sound Digest Archive v01.n481
You'll blow up your output transformer. When it runs unloaded with a
signal, VERY high voltage spikes are created which will short out the
winding insulation. No signal, no problem, provided the amp does not
oscillate.
Chris Beck
See my web page at: http://www.execpc.com/~n9zes/index.htm
- ----------
> From: Alex Megann <Alex.P.Megann@soc.soton.ac.uk>
> To: sound@lists.io.com
> Subject: Unloaded OTs
> Date: Thursday, November 05, 1998 4:19 AM
>
> Here's a question I have been mulling over for a few years,
> and which may have more relevance to me recently (more
> explanation later!).
>
> We're told that one should never operate a solid-state amp
> into a short circuit, but on the other hand never to use a
> valve amplifier with no load across the output. I understand
> roughly the reasons why in both cases - thermal runaway and
> low output impedance in the former, and Faraday's Law (back
> EMF produced by changing the current through an inductor) in
> the latter.
>
> What are the long-term consequences of operating a valve
> amplifier with the output transformer unloaded (or nearly
> unloaded), though?
>
> Alex
>
=========================================================================
From: Alex Megann <Alex.P.Megann@soc.soton.ac.uk>
Subject: Unloaded OTs
Date: Thu, 5 Nov 1998 10:19:47 GMT
Source: Sound Digest Archive v01.n481
Here's a question I have been mulling over for a few years,
and which may have more relevance to me recently (more
explanation later!).
We're told that one should never operate a solid-state amp
into a short circuit, but on the other hand never to use a
valve amplifier with no load across the output. I understand
roughly the reasons why in both cases - thermal runaway and
low output impedance in the former, and Faraday's Law (back
EMF produced by changing the current through an inductor) in
the latter.
What are the long-term consequences of operating a valve
amplifier with the output transformer unloaded (or nearly
unloaded), though?
Alex
=========================================================================
From: Alex Megann <Alex.P.Megann@soc.soton.ac.uk>
Subject: Unloaded OTs
Date: Thu, 5 Nov 1998 13:29:00 GMT
Source: Sound Digest Archive v01.n481
Thanks for the posts on this - the feeling seems to be that
the main probable result would be to damage the insulation in
the transformer, with possible flashover in the output valves.
The reason I asked was in connection with the post I sent a
couple of weeks ago ("Rustling noise in Croft amps"). I used
them for a few years in "biamp" mode - one channel of one
amp feeding the low-pass leg of the crossover, and the other
feeding the high-pass leg. Now the high-pass filter offers
no DC load at all to the amp to damp out the OT - could this
have damaged the amp? I posted a query to this effect to the
Analogue Addicts list a while back, and although the only
responses I got were reassuring, I'm still not satisfied.
Has anyone else used a valve amp to drive a passive high-pass
crossover with no ill effects? I can't see how damaged OT
insulation could produce the noise I hear. How can I tell if
there has been any flashover in the output tubes?
Alex
=========================================================================
From: "Chris Beck" <cbeck@brewercompany.com>
Subject: Re: Unloaded OTs
Date: Thu, 5 Nov 1998 11:29:38 -0600
Source: Sound Digest Archive v01.n482
Interesting, however Jack at ELectra-Print told me once about replacing a
pair of OPTs on a SE amp that the guy ran unloaded that blew up.
Chris Beck
See my web page at: http://www.execpc.com/~n9zes/index.htm
- ----------
> From: John Levreault <jlevro@mediaone.net>
> To: Chris Beck <cbeck@brewercompany.com>
> Cc: Alex Megann <Alex.P.Megann@soc.soton.ac.uk>; sound@lists.io.com
> Subject: Re: Unloaded OTs
> Date: Thursday, November 05, 1998 11:16 AM
>
> Chris Beck wrote:
>
> > You'll blow up your output transformer. When it runs unloaded with a
> > signal, VERY high voltage spikes are created which will short out the
> > winding insulation. No signal, no problem, provided the amp does not
> > oscillate.
>
> This may be true for push-pull amps using negative feedback. However, a
> typical SET without feedback will generally not have this problem. View
> it as a triode amp with a plate choke and no output load.
>
> JL
>
>
> >
> >
> > Chris Beck
> >
> > See my web page at: http://www.execpc.com/~n9zes/index.htm
> >
> > ----------
> > > From: Alex Megann <Alex.P.Megann@soc.soton.ac.uk>
> > > To: sound@lists.io.com
> > > Subject: Unloaded OTs
> > > Date: Thursday, November 05, 1998 4:19 AM
> > >
> > > Here's a question I have been mulling over for a few years,
> > > and which may have more relevance to me recently (more
> > > explanation later!).
> > >
> > > We're told that one should never operate a solid-state amp
> > > into a short circuit, but on the other hand never to use a
> > > valve amplifier with no load across the output. I understand
> > > roughly the reasons why in both cases - thermal runaway and
> > > low output impedance in the former, and Faraday's Law (back
> > > EMF produced by changing the current through an inductor) in
> > > the latter.
> > >
> > > What are the long-term consequences of operating a valve
> > > amplifier with the output transformer unloaded (or nearly
> > > unloaded), though?
> > >
> > > Alex
> > >
>
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: Unloaded OTs
Date: Thu, 05 Nov 1998 12:16:31 -0500
Source: Sound Digest Archive v01.n482
Chris Beck wrote:
> You'll blow up your output transformer. When it runs unloaded with a
> signal, VERY high voltage spikes are created which wil