Sound Practices Mailing List Files - Volume 2
=========================================================================
From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: [JN] P-12 jensens
Date: Fri, 06 Aug 1999 11:03:55 -0400
Source: Sound Digest Archive v02.n226
joe wrote:
> My advice: Try a P-12 Jensen with a nice hard cone, add a tweeter if
> necessary.
>
> Joe
>
my question:
are these the same as was used in old guitar amps
jensen "special design"
i have a pair of p-12-n, i believe
may have the suffix screwed up
maybe p12-q ???
(according to the gerald weber guitar amp book
the ones i have are one notch from the
"top of the line" model...)
i had (ever distant) plans of building a pair of
guitar amps with them.
one for me and one for my brother...
would these be candidates for some sort of
almost-full-range stereo speaks...
the efficiency is something near 100db/w/m
if i recall correctly.
these are apparently being re-issued.
i think antique electronics
(www.tubesandmore.com)
is a distributer.
so what did you have in mind, joe?
bob.d.
=========================================================================
From: "Henry Platt" <hnplatt@massed.net>
Subject: Re: [JN] P-12 jensens
Date: Fri, 06 Aug 1999 12:40:46 -0700
Source: Sound Digest Archive v02.n226
Hi all.
Isn't the P12 the permanent magnet version of the Field coil Jensen A12?
What type of box should one use for these?
Henry
- ----------
>From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
>To: sound@io.com
>Subject: [JN] P-12 jensens
>Date: Fri, Aug 6, 1999, 8:03 AM
>
> joe wrote:
>
>> My advice: Try a P-12 Jensen with a nice hard cone, add a tweeter if
>> necessary.
>>
>> Joe
>>
> my question:
>
> are these the same as was used in old guitar amps
>
> jensen "special design"
>
> i have a pair of p-12-n, i believe
>
> may have the suffix screwed up
>
> maybe p12-q ???
>
> (according to the gerald weber guitar amp book
> the ones i have are one notch from the
> "top of the line" model...)
>
> i had (ever distant) plans of building a pair of
> guitar amps with them.
> one for me and one for my brother...
>
> would these be candidates for some sort of
> almost-full-range stereo speaks...
>
> the efficiency is something near 100db/w/m
> if i recall correctly.
>
> these are apparently being re-issued.
> i think antique electronics
> (www.tubesandmore.com)
> is a distributer.
>
> so what did you have in mind, joe?
>
> bob.d.
>
=========================================================================
From: Joe Roberts <jroberts@io.com>
Subject: Re: [JN] P-12 jensens
Date: Fri, 06 Aug 1999 13:23:40 +0000
Source: Sound Digest Archive v02.n227
> are these the same as was used in old guitar amps
>
> jensen "special design"
>
> i have a pair of p-12-n, i believe
>
Yep, that's them. Sound pretty good. Try 'em out.
Joe
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] P-12 jensens
Date: Fri, 6 Aug 99 17:58:26 -0400
Source: Sound Digest Archive v02.n227
Gang,
If anyone is interested in a pair of A12-PM Jensen, these are the Alnico
version.
I have a pair of nice ones, trades are welcome!
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: [JN] P-12 jensens
Date: Sat, 07 Aug 1999 00:26:48 GMT
Source: Sound Digest Archive v02.n227
On Fri, 06 Aug 1999 13:23:40 +0000, Joe Roberts <jroberts@io.com>
wrote:
>> jensen "special design"
>>
>> i have a pair of p-12-n, i believe
>>
>Yep, that's them. Sound pretty good. Try 'em out.
Have you tried the Weber VST copies of the old Jensen guitar speakers,
or the new Jensen reissues?
- --dnb
=========================================================================
From: "leamare" <leamare@vislink.it>
Subject: [JN] Pacific Audio line tranformer opinions?
Date: Wed, 27 Jan 1999 18:35:53 +0100
Source: Sound Digest Archive v02.n014
Hello,
I read about the Pacific Audio L106 line transformer, sold by La Maison de
l'Audiophile.
It consists of a transformer which replaces the line preamp; overall gain
is said to be 12 db.
Anyone tried it or any other comparable unit?
Opinions?
Sunny regards from Italy (eheheheh)
Armando
=========================================================================
From: "Cameron Brook" <cambrook@cyllene.uwa.edu.au>
Subject: [JN] pair ALTEC "288- 16G"
Date: Mon, 6 Dec 1999 09:08:09 +0800
Source: Sound Digest Archive v02.n354
some Joes might be interested in these,
no connection with seller etc etc
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=214265396
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: [JN] Pair of 280 Wztt Hammond Outputs on eBay
Date: Tue, 08 Feb 2000 20:46:12 -0800
Source: Sound Digest Archive v02.n440
In case anyone is interested. I have no connection with this, just
recall some big-amp talk here recently and thought I would pass it on.
One more day to go, current bid is $172.50 for the pair. AES price is
$205.50 each.
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=252440690
=========================================================================
From: Dan Kerl <dlkerl@ro.com>
Subject: Re: [JN] Pair of 280 Wztt Hammond Outputs on eBay
Date: Wed, 09 Feb 2000 08:44:30 -0600
Source: Sound Digest Archive v02.n440
"Daniel J. Marshall" wrote:
>
> In case anyone is interested. I have no connection with this, just
> recall some big-amp talk here recently and thought I would pass it on.
> One more day to go, current bid is $172.50 for the pair. AES price is
> $205.50 each.
>
> http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=252440690
Also, from
http://www.angela.com/catalog/transformers/Hammond_Transformers.html
1650W 280W, 1900 ct, 4/8/16 ohm, 6L6GC, 5881, EL34, 6550B, KT88, SALE!!!
$148!!
Might make a good SVT clone.
- --
Dan Kerl
dlkerl@ro.com
=========================================================================
From: Ken Gilbert <ride5000@ride.ri.net>
Subject: Re: [JN] Pair of 280 Wztt Hammond Outputs on eBay
Date: Wed, 09 Feb 2000 17:50:08 -0500
Source: Sound Digest Archive v02.n441
>Also, from
>http://www.angela.com/catalog/transformers/Hammond_Transformers.html
>
>1650W 280W, 1900 ct, 4/8/16 ohm, 6L6GC, 5881, EL34, 6550B, KT88, SALE!!!
>$148!!
>
>Might make a good SVT clone.
Dan, et al,
i've got two of them in a big ass guitar amp sitting outside in my garage... i
just threw down 200 bucks on that auction and was immediately outbid (proxy).
TWO of them will make an SVT _killer_. that price from angela is damned good.
i picked mine up a year ago on rat from a guy in canada... he had two
consecutively serial-numbered units, which was nice, for $300, which was a
steal at the time. i don't really have the discretionary income to give that
high bidder a run for his money... figure on 50 for the shipping, so i'd go as
high as 250, but only if i really wanted them!
ken
=========================================================================
From: Rick Francis <rfrancis@glasscity.net>
Subject: [JN] Pair of OPTs from DuKane PP 6CD6 50-watt amps
Date: Thu, 02 Sep 1999 07:28:07 -0400
Source: Sound Digest Archive v02.n269
The amps were cannibalized for the PTs, but I have this pair of OPTs for
someone. They were rusty, but I cleaned them up, used Rustoleum primer,
then used Rustoleum black enamel. I think they look pretty good. Lots of
secondary taps, including 70v. No UL taps, sorry.
I'll measure dimensions if anyone wants, but be assured they are fairly
hefty -- the size you would expect for EL-34s, 7591, etc. I think they
would be great for a couple of guitar amps, or a budget stereo amp. How
about $25/pair plus shipping, and I'll throw in a copy of the original
schematic? Or will swap for something interesting.
Rick
=========================================================================
From: Rick Francis <rfrancis@glasscity.net>
Subject: [JN] Pair plate transformers on ebay
Date: Tue, 28 Dec 1999 10:20:11 -0500
Source: Sound Digest Archive v02.n373
There's a pair of plate transformers on ebay, ending today:
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=224594048
Look at the picture and you'll see more info than is given in the
description. It's 1120 vct, plus another winding. Not high current, but
might work great for a minimalist 845 amp. If I didn't have a pile of iron
in my basement, I'd probably get them.
Rick
=========================================================================
From: Scott Grammer <tubedude@sunnetusa.net>
Subject: [JN] Panasonic DVD
Date: Fri, 26 Nov 1999 20:04:09 -0500
Source: Sound Digest Archive v02.n346
I just heard that Panasonic is marketing a DVD player billed as a "DVD
Audio Player that also plays movies". In other words, they are
emphasizing the audio and it just happens to play movies. It will
support sampling rates up to 192kHz, and is 24 bit, of course. I'll find
out the model number and whatever else I can and report back.
Scott.
- --
"To save every cog and wheel is the first
precaution of intelligent tinkering." -Aldo Leopold.
What if there were no hypothetical questions?
=========================================================================
From: Jan Nielsen <sound@image.dk>
Subject: Re: [JN] Panasonic DVD
Date: Sat, 27 Nov 1999 22:37:05 +0100
Source: Sound Digest Archive v02.n346
Hi Scot,
This would be the Technics DVD A10.
I had it home for a short review - only one week. The price here in Denmark
is approx. 11.000 DKR.
Only one DVD-Audio Disc was supplied and the quality was a bit mixed. The
top was OK but at bit from the best - i.e. high end CD's like Mark Levinson
and Accuphase. The most impressive was the low end, which is tight with a
lot of weight and dynamics. Picture quality and surround-modes (built in DTS
konverter!) is the typical high quality you get from the best DVD-players.
It's still too soon to make any conclusions. The future will show (as the
CD-media has) what the DVD-Audio standard can give us ind extra resoultion
and "analog-like" quality.
Regards,
Jan Nielsen
Scott Grammer wrote:
> I just heard that Panasonic is marketing a DVD player billed as a "DVD
> Audio Player that also plays movies". In other words, they are
> emphasizing the audio and it just happens to play movies. It will
> support sampling rates up to 192kHz, and is 24 bit, of course. I'll find
> out the model number and whatever else I can and report back.
>
> Scott.
> --
> "To save every cog and wheel is the first
> precaution of intelligent tinkering." -Aldo Leopold.
>
> What if there were no hypothetical questions?
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] Panasonic DVD
Date: Mon, 29 Nov 99 10:57:41 -0500
Source: Sound Digest Archive v02.n347
>I just heard that Panasonic is marketing a DVD player billed as a "DVD
>Audio Player that also plays movies". In other words, they are
>emphasizing the audio and it just happens to play movies. It will
>support sampling rates up to 192kHz, and is 24 bit, of course. I'll find
>out the model number and whatever else I can and report back.
Scott,
Supposedly the Technics and Panasonic are the first two fully released Audio grade DVD's.
The Technics unit is suppose to be real nice!
~~~~ From Panasonic ~~~~~
Thank you for your e-mail inquiry concerning Panasonic DVD products.
Please review the latest press release on DVD audio. These units should be
available late 99, early 2000. There is only preliminary information
available.
SECAUCUS, NJ (July 27, 1999) - Panasonic Consumer Electronics Company
(PCEC), the first company to show DVD-Audio players in the United States
earlier this year, affirms its commitment to this new and exciting audio
medium by being the first to announce delivery timing and suggested pricing
for two models, the Panasonic-brand DVD-A7 and the Technics DVD-A10.
Beginning this October, both models will be shipped to dealers nationwide.
The Panasonic DVD-A7 has a manufacturer's suggested retail price of $999.95.
The Technics DVD-A10 carries a manufacturer's suggested retail price of
$1,199.95.
These next generation audio players can be easily incorporated into your
home entertainment system. But while the players will accept and play
conventional CDs, future DVD-Audio discs will be reproduced with far greater
fidelity then presently available. And DVD-Audio is capable of much more.
Attached to a home entertainment's television or projection TV, a DVD-Audio
player can also reproduce video: graphics, text, music videos, and more can
be shown. Additionally, since the player is compatible with DVD Video discs,
your favorite DVD movies can be played as well-along with up to 5.1 channels
of Dolby Digital® and DTS® multi-channel sound. Want more? Future DVD-Audio
discs could even contain URL addresses for instant access to relevant Web
sites as you listen-or watch-a DVD-Audio disc.
"DVD-Audio not only far exceeds the audio quality of conventional CD
reproduction, but provides new enhancements that can combine listening with
a truly interactive experience," says Gene Kelsey, vice president and
general manager of Panasonic's Audio Group. "A DVD-Audio/Video player will
be the cornerstone component of all home entertainment systems of the near
future."
The true acceptance of a new audio format means equal enthusiasm from the
software industry as well. And that is already happening. "Universal Music
Group is looking forward to supporting the first new audiophile standard
since the introduction of CDs almost twenty years ago," says Lisa Farris,
vice president of marketing for Universal Music Group - eCAT. "By providing
recording artists with an expanded aural palette, DVD-Audio's better than CD
quality stereo and multi-channel surround sound showcases a whole new
listening experience for the consumer. Universal Music Group is preparing
releases from a wide range of artists covering every genre in conjunction
with the launch of the DVD-Audio player."
Conforming to the newly established DVD-Audio standard, and containing an
encryption system to prevent unauthorized disc duplication, DVD-Audio takes
advantage of the digital technology originally developed for DVD-Video. It
uses the advanced format's vast data storage potential to deliver astounding
sound enriched with the nuance, warmth and subtle overtones of a live
musical performance.
To accomplish this, 2-channel DVD-Audio uses a sampling frequency of 192kHz
- - more than four times that of CD - to extend the playback high-frequency
response to an incredible 96kHz. The higher frequency reproduction gives
live instruments their timbre or resonance, which is often lost on a compact
disc. The crash of cymbals, for instance, produces frequencies well above
20kHz - inaudible to the ear but important to retaining the instrument's
distinct expression and the integrity of the music.
In addition, a new Digital-To-Analog Converter (DAC), based on MASH*
technology and refined by Matsushita for 192kHz/24-bit DVD-Audio use, gives
these players the ability to distinguish levels of sound using 24-bit
quantization (vs. 16-bit maximum for CD). This reduces background noise to
imperceptible levels. The new DAC is also combined with a DIGITAL RE-MASTER
PROCESSING circuit, which uses audio dithering techniques to increase the
frequency response and dynamic range of conventional CDs as well.
DVD-Audio is fully multi-channel sound compatible and uses PCM (Pulse Code
Modulation) for all channels, presenting a new level of multi-channel sound
quality, unprecedented realism in ambience reproduction, and the potential
to create radically different sound spaces. Incorporating both Dolby
Digital® and DTS® decoders, the players can decode music and soundtracks
recorded in up to 5.1 channels (including a subwoofer) to give listeners the
ambience and enveloping effect of a live performance.
Also like its video cousin, DVD-Audio is capable of single- or dual-layer
capacity on one or both disc sides. At its highest rate (192kHz/24-bit
2-channel PCM), the format can store 74 minutes of music on a single-side of
a single-layer disc. At lower recorded rates, that figure can balloon to 400
minutes - or more than 6-1/2 hours of music at CD equivalent quality.
Additionally, the format uses a technique called Lossless Coding, which is a
compression system that removes redundancies in the audio signal to enhance
recording capacity and enable virtually perfect reconstruction of the
original signal. Using Lossless Coding, up to 74 minutes of 96kHz/24-bit/6
channel recordings can be squeezed onto one side of the DVD-Audio disc. An 8
cm disc is also an option for music singles or other short programs.
The extensive storage space not only permits extended-range audio, but full
MPEG-2 video, still images, and text as well, to fuse pictures and sounds
into a new world of entertainment interactivity. When connected to a
television or computer monitor for example, and depending on disc content,
DVD-Audio players allow "listeners" to watch music videos with unparalleled
audio and DVD-quality video, view "photo albums" of band members, or read
track titles, song lyrics and liner notes on the screen. Internet URL
addresses embedded in the disc can also link listeners directly to relevant
Web sites when the player is connected to a PC. And, visual menus can help
users easily navigate all the offerings on a disc.
While the Panasonic DVD-A7 provides extraordinary audio and video quality,
the Technics DVD-A10 is a step above and designed to address the needs of
discriminating audiophiles. For example, to complete an uncompromising
design, the audio power supply in the DVD-A10 incorporates a system called
Advanced Virtual Battery Operation. Using a capacitor to supply its charged
power to the audio reproduction circuitry, the technique simulates a battery
(pure source of DC current) to virtually eliminate power supply "noise" for
faithful reproduction of even the smallest signal information. Additionally,
an R-Core transformer, which has a rounded shape to help minimize leakage
flux and noise, replaces the conventional transformers with their
squared-off corners and uneven flux patterns. And TA-KE II electrolytic
capacitors are used throughout for better mid-high frequency response with
lower distortion. Even the cabinetry is impressive: a sleek champagne gold
component with a special vibration damping base.
"DVD-Audio is about to unleash an entirely new revolution in what we now
simply call home audio," says Kelsey. "It will be an attack on both our
aural and visual senses, taking the performer yet another giant step closer
into our living rooms."
Panasonic and Technics consumer electronics products are marketed in the
United States by Panasonic Consumer Electronics Company (PCEC), a division
of Matsushita Electric Corporation of America (MECA). MECA is the principal
North American subsidiary of Matsushita Electric Industrial Co., Ltd.,
(NYSE: MC) of Japan, one of the world's largest producers of electronic and
electric products and a key developer of technology for DVD, mobile DVD,
DVD-ROM, DVD-RAM and DVD Audio. Prices are in U.S. currency. (Consumers
seeking more information on the company's products can call Panasonic's
Customer Call Center at 800-211-PANA or access Panasonic's home page at
www.panasonic.com <http://www.panasonic.com> . or www.technicsusa.com
<http://www.technicsusa.com> . Media interested in Panasonic or Technics
press releases can gain information via the Panasonic Web site or through
New Directions Public Relations' toll-free fax-back system at 888-734-7490.)
Specifications and design subject to change without notice.
*Matsushita Electric Industrial Co., Ltd., incorporates MASH (multi-stage
noise shaping technology) in its products under technical license from NTT.
Dolby Digital® is a trademark of Dolby Laboratories Licensing Corporation.
DTS® is a trademark of Digital Theater Systems, Inc.
Down load the press release
MAC: DVD-Audio-31.txt.sea.hqx | PC: DVD-Audio-31.zip
BACK
Copyright ©1998 Matsushita Electric Corporation of America. All rights
reserved.
If we can further assist you other Panasonic, Technics or Quasar products;
please contact the Panasonic Customer Call Center (1-800-211-PANA). For your
convenience, the call center is open from 9:00 am to 9:00 p.m. (est.;
Mon-Fri) and from 9:00 am to 7:00 p.m. (est.; Sat/Sun).
Best regards,
Panasonic Customer Call Center
~~~
Gordon
=======> Wavelength Audio <=======
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: Nicholas McKinney <nick@lambdacoustics.com>
Subject: Re: [JN] Panasonic DVD
Date: Mon, 29 Nov 1999 13:35:36 -0500
Source: Sound Digest Archive v02.n348
At 10:57 AM 11/29/99 -0500, J. Gordon Rankin wrote:
>Supposedly the Technics and Panasonic are the first two fully released Audio
>grade DVD's.
>
>The Technics unit is suppose to be real nice!
Hi Folks, I didn't see it anywhere, but do they play CDR discs?
Very important option for me at least, most DVD players don't allow for this.
Nick
Nicholas McKinney
Lambda Acoustics Inc.
www.lambdacoustics.com
www.onelist.com/community/LambdaDrivers
=========================================================================
From: Scott Grammer <tubedude@sunnetusa.net>
Subject: Re: [JN] Panasonic DVD
Date: Mon, 29 Nov 1999 22:33:57 -0500
Source: Sound Digest Archive v02.n348
Nicholas McKinney wrote:
(snip)
> Hi Folks, I didn't see it anywhere, but do they play CDR discs?
>
> Very important option for me at least, most DVD players don't allow for this.
>
> Nick
Nick:
You have to be careful putting CDR's in a DVD player. DVD players use a
much more powerful laser than CD players, and they can erase CDR's!
Scott.
- --
"To save every cog and wheel is the first
precaution of intelligent tinkering." -Aldo Leopold.
What if there were no hypothetical questions?
=========================================================================
From: "Multi-Volti Devices" <multi-volti@softhouse.com>
Subject: [JN] paper in oil caps
Date: Wed, 12 May 1999 23:47:20 -0400
Source: Sound Digest Archive v02.n142
Hello:
Not sure if I already asked this...
I have some nos 0.1 uF 450 vac paper in oil in ceramic tube/axial lead caps
(estimated DC V 1100+). (Matsushita Industrial)
I have given some to some field testers/listeners and so far they are very
happy with them in PP and SE applications.
I have had some inquiry about selling additional ones, but don't know what
they're worth. If they're not worth much, I'll keep them for my own designs.
If they're worth anything, I might unload some to fund other audio project
expenses.
Thanks
Murray
=========================================================================
From: Ishmael349@aol.com
Subject: [JN] Re:paper voice coils
Date: Mon, 25 Jan 1999 10:16:34 EST
Source: Sound Digest Archive v02.n011
I actually built that speaker. Wish I could find the phone number of the guy
who I gave it to, he was a recording engineer and says he, "loves it" and is
"still using it". I built mine out of MDF and I remember playing with some
stuffing. I bet it sounds good. Better yet, look for drivers with PAPER
voice coils. The sound character of a driver is (in my opinion) influenced by
the material of the voice coil than the cone material. Paper, with natural
glues, is (for me, and Kondo) the best. Remember everything sounds like what
it is made of. Try it!
Herb
=========================================================================
From: Mindaugas <mk@is.lt>
Subject: [JN] Paper vs metalized foil
Date: Mon, 1 Mar 1999 10:00:45 +0200 (EET)
Source: Sound Digest Archive v02.n064
Hello all.
I found in the basement old vintage tube amp where all caps are old (motor
run) paper in oil caps. Does it makes sense to replace them all with the
metalized polyprophylene foil Wima caps (I am considering ordering these)?
Any thoughts would be appreciated.
Mindaugas
mk@is.lt
=========================================================================
From: Dan Marshall <mdaniel7@uswest.net>
Subject: Re: [JN] Papst Motor Puzzle
Date: Tue, 15 Aug 2000 09:30:45 +0000
Source: Sound Digest Archive v02.n629
It sounds like what you have is a three phase motor. It ought to run in
single phase with a cap though, after a fashion, and, assuming it is a
three-phase motor, it would not matter what combination of leads you
used, any combo that caused it to turn in the desired direction of
rotation would be equivalent to any other connection. As to why it
doesn't run, I couldn't say. Are you sure it is rated for 115 volts
line voltage. Three phase would be a preferable driving source.
Three-phase motors will run on single phase with any two leads
energized, if you give it a spin to get it started. The cap ought to
take care of this though, as long is the motor is lightly loaded. Try
winding a string around the shaft and give it a brisk spin when it is
switched on (with two terminals energized and see if it will run.
DM
Kalman Rubinson wrote:
>
> Having found what appears to be a great drive for
> my turntable project, I am stymied by it.
>
> I have two samples of a NOS Papst motor which is supposed to
> be an AC synchronous motor built for use as a capstan drive
> in studio tape recorders like Ampex and Tascam. There are
> three leads and the following printing on each:
> PAPST-MOTOREN KG
> 9018032029
> HSKZ 32.80-12-135D
> 115V 60Hz 6uF Marz.77
>
> The rotor turns freely indicating that there are no bearing
> problems. Connecting the AC to BLK and RED and the 6uF cap
> between RED and OR, the motor buzzes gently but will not
> turn on its own. Other connection arrangements give similar
> outcome.
>
> Measurements give 165ohms between any(!) two leads. This
> holds for both samples. (I'd have expected one measurement
> to be the sum of the other two on a typical synchronous
> motor.)
>
> The literature that Papst has dredged up from their archives
> is puzzling since it refers to this model but with much
> lower capacitance (and much more German text) than printed
> on the motors.
>
> Any ideas?
>
> Kal
=========================================================================
From: Kalman Rubinson <kr4@is2.nyu.edu>
Subject: [JN] Papst Motor Puzzle
Date: Tue, 15 Aug 2000 11:38:01 -0400 (EDT)
Source: Sound Digest Archive v02.n629
Having found what appears to be a great drive for
my turntable project, I am stymied by it.
I have two samples of a NOS Papst motor which is supposed to
be an AC synchronous motor built for use as a capstan drive
in studio tape recorders like Ampex and Tascam. There are
three leads and the following printing on each:
PAPST-MOTOREN KG
9018032029
HSKZ 32.80-12-135D
115V 60Hz 6uF Marz.77
The rotor turns freely indicating that there are no bearing
problems. Connecting the AC to BLK and RED and the 6uF cap
between RED and OR, the motor buzzes gently but will not
turn on its own. Other connection arrangements give similar
outcome.
Measurements give 165ohms between any(!) two leads. This
holds for both samples. (I'd have expected one measurement
to be the sum of the other two on a typical synchronous
motor.)
The literature that Papst has dredged up from their archives
is puzzling since it refers to this model but with much
lower capacitance (and much more German text) than printed
on the motors.
Any ideas?
Kal
=========================================================================
From: Christian Rintelen <Christian@rintelen.ch>
Subject: Re: [JN] Papst Motor Puzzle
Date: Tue, 15 Aug 2000 18:12:53 +0200
Source: Sound Digest Archive v02.n629
This is a multi-part message in MIME format.
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Could it be that you have a 3 phase AC synchronous motor? (This was
often done on very hiqh quality motors - EMT also uses 3 phase
motors). Check out
http://www2.cds.ne.jp/~yogawa/emt930/emt930_CIRCUIT.gif - this
schematic shows how the EMT 3 phase motor is connected with a 1.5 uF
cap and a 2k pot for phase adjustment.
What does the "much more German text" say? I can probably help...
Christian
Kalman Rubinson wrote:
> Having found what appears to be a great drive for
> my turntable project, I am stymied by it.
>
> I have two samples of a NOS Papst motor which is supposed to
> be an AC synchronous motor built for use as a capstan drive
> in studio tape recorders like Ampex and Tascam. There are
> three leads and the following printing on each:
> PAPST-MOTOREN KG
> 9018032029
> HSKZ 32.80-12-135D
> 115V 60Hz 6uF Marz.77
>
> The rotor turns freely indicating that there are no bearing
> problems. Connecting the AC to BLK and RED and the 6uF cap
> between RED and OR, the motor buzzes gently but will not
> turn on its own. Other connection arrangements give similar
> outcome.
>
> Measurements give 165ohms between any(!) two leads. This
> holds for both samples. (I'd have expected one measurement
> to be the sum of the other two on a typical synchronous
> motor.)
>
> The literature that Papst has dredged up from their archives
> is puzzling since it refers to this model but with much
> lower capacitance (and much more German text) than printed
> on the motors.
>
> Any ideas?
>
> Kal
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=========================================================================
From: Kalman Rubinson <kr4@is2.nyu.edu>
Subject: [JN] Re: Papst motor puzzle
Date: Wed, 16 Aug 2000 21:07:12 -0400 (EDT)
Source: Sound Digest Archive v02.n630
Hooray! I got the motor running (got out on the
highway!) by using a 2 to 4 mfd cap, not the specified
6mfd cap. However, it must be a 3phase motor and running
it this way does not result in low vibration.
Any wisdom on triphase supplies? I have a few ideas.
Kal
=========================================================================
From: Ed Faulkner <efaulkne@wsunix.wsu.edu>
Subject: [JN] PA question
Date: Thu, 17 Jun 1999 10:18:13 -0700
Source: Sound Digest Archive v02.n181
I am assisting a department here at WSU again with their PA system (Altec
A5s) in a large multipurpos room. They are experiencing a slight delay in
the sound system and I would appreciate any input you people might have.
Recently they removed 70V line transformers and are driving the speakers
from a transistor amp with a maximum cable length of about 100 ft. Can some
cables create a delay line when used this way? The wire is nothing special,
two insulated conductors and a plenum grade sheath.
If anyone feels this question should not be on this list please let me
know. I no longer suscribe to other groups because of time limitations and
appreciate any assistance you may be able to provide. Please respond
directly to efaulkne@wsu.edu unless the information is usefull to the list.
_____________________________
Ed Faulkner \ through a child's eyes
CMT Supervisor \ sky is blue
Washington State University \ grass is green
Pullman, WA,99164 \ I want to see again
(509) 335-7566 \
efaulkne@wsu.edu \______________________
=========================================================================
From: Scott Grammer <tubedude@cdc.net>
Subject: Re: [JN] PA question
Date: Thu, 17 Jun 1999 16:31:17 -0400
Source: Sound Digest Archive v02.n181
Ed Faulkner wrote:
> I am assisting a department here at WSU again with their PA system (Altec
> A5s) in a large multipurpos room. They are experiencing a slight delay in
> the sound system and I would appreciate any input you people might have.
>
> Recently they removed 70V line transformers and are driving the speakers
> from a transistor amp with a maximum cable length of about 100 ft. Can some
> cables create a delay line when used this way? The wire is nothing special,
> two insulated conductors and a plenum grade sheath.
>
> (snip)
Ed:
When you say a "delay", do you mean an echo? Or is there some period of time
between when a sound reaches a microphone and the time it leaves a speaker?
No cable is going to create an audible delay. (OK, come on, somebody argue with
me. I know it's going to happen. Out with it.) If you have an echo, it is most
likely a reflection from the back wall of the auditorium. This is a common
problem, especially with auditoriums seating between 200 and 1,000 people. Only
serious sound deadening materials or, better yet, remodeling will cure that. If
you are experiencing a true delay, between the mic and speaker, then there is a
delay line (electronic) in the system somewhere. It may have been installed to
reduce feedback (I hope not) or to use for "echo effects". Find it and take it
out of line.
BTW, some active crossovers and equalizers have delay lines built in for time
alignment of speaker drivers. This may be where the delay line is hiding.
Good luck!
S.G.
- --
TubeDude's Webpage of Vacuum Tube Lore! http://www.cdc.net/~tubedude/
Smoke Free Youth! http://www.cdc.net/~tubedude/smokefreeyouth.html
The Price of Privacy. http://www.cdc.net/~tubedude/privacy.html
"The nice thing about standards is that you have so many to choose from."
-- Andrew S. Tanenbaum, _Computer Networks_, 2nd ed, p.254
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: [JN] PA question
Date: Thu, 17 Jun 1999 19:12:51 GMT
Source: Sound Digest Archive v02.n181
On Thu, 17 Jun 1999 10:18:13 -0700, Ed Faulkner
<efaulkne@wsunix.wsu.edu> wrote:
>They are experiencing a slight delay in
>the sound system and I would appreciate any input you people might have.
This sounds more like a function of the room acoustics than a problem
with the system.
- --dnb
=========================================================================
From: davidbarnett@aristotle.net (David Barnett)
Subject: Re: [JN] PA question
Date: Fri, 18 Jun 1999 22:23:50 GMT
Source: Sound Digest Archive v02.n181
On Thu, 17 Jun 1999 10:18:13 -0700, Ed Faulkner
<efaulkne@wsunix.wsu.edu> wrote:
> They are experiencing a slight delay in
>the sound system and I would appreciate any input you people might have.
This is obviously a basic design flaw of the Altec A5. Get them to
buy a set of Peavey speakers, and I'll gladly come and haul off the
A5s for no charge.
- --dnb
=========================================================================
From: Scott Grammer <tubedude@cdc.net>
Subject: Re: [JN] PA question
Date: Fri, 18 Jun 1999 21:39:18 -0400
Source: Sound Digest Archive v02.n182
David Barnett wrote:
> (snip)
>
> This is obviously a basic design flaw of the Altec A5. Get them to
> buy a set of Peavey speakers, and I'll gladly come and haul off the
> A5s for no charge.
>
> --dnb
HA!
ROFLMAO!
S.G.
- --
TubeDude's Webpage of Vacuum Tube Lore! http://www.cdc.net/~tubedude/
Smoke Free Youth! http://www.cdc.net/~tubedude/smokefreeyouth.html
The Price of Privacy. http://www.cdc.net/~tubedude/privacy.html
"The nice thing about standards is that you have so many to choose from."
-- Andrew S. Tanenbaum, _Computer Networks_, 2nd ed, p.254
=========================================================================
From: Allen Wright <AllenVSE@compuserve.com>
Subject: [JN] Parafeed?
Date: Wed, 18 Oct 2000 05:56:29 -0400
Source: Sound Digest Archive v02.n696
Joes and Joette(s),
Re Parafeed:
I am not trying to be smart here - Parafeed is strongly recommended by some
serious heavy hitters, yet I have these conflicts:
a/ It is my understanding that one of the generally assumed "problems" with
push-pull topology is that without signal the OPT sits with zero flux
(assuming the DC standing currents are balanced) and that when some signal
arrives the OPT must swing through a quite non-linear segment of it's BH
curve before reaching a more optimum portion. And does this non-linear to
linear dance on every zero crossing transition of the signal. Yes?
b/ A (conventional) SE amp correctly matched to it's (air-gapped) OPT runs
a standing current that places it's operating condition right in the middle
of the most linear part of the BH curve area - and in normal operation
should never swing down (or up) as far as the curved portion the P-P amp
cannot advoid. Yes?
c/ And this standing current in the OPT is one of the theroretical
advantages of the SE topology - Yes?
d/ A single ended parafeed amp (normally) is is choke loaded and cap feeds
an OPT - which doesn't have/need an air gap because it doesn't carry any DC
current. Yes?
Question 1: Why then doesn't a parafeed amp suffer exactly the same "non
linearity" around the zero crossing point that P-P (supposedly) does?
Question 2: If it does have this non linear distortion due to the BH curve,
what are the theoretical advantages of parafeed that outweigh this and yet
are not possible in a PP design?
Very curious on these points...
Allen (VSE)
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Parafeed?
Date: Wed, 18 Oct 2000 10:22:25 GMT
Source: Sound Digest Archive v02.n696
Hi,
>c/ And this standing current in the OPT is one of the theroretical
>advantages of the SE topology - Yes?
Yes. Also remeber that there some serious energy stored in that primary
inductance of the OPT....
>Question 1: Why then doesn't a parafeed amp suffer exactly the same "non
>linearity" around the zero crossing point that P-P (supposedly) does?
But it does, unless you use OPT's with Permalloy or such in parafeed you
have the same problem in parafeed as in PP.
>Question 2: If it does have this non linear distortion due to the BH curve,
>what are the theoretical advantages of parafeed that outweigh this and yet
>are not possible in a PP design?
Non that I can see (or hear for that effect).
I commented before that IMHO much of the "improved bass" with parafeed is in
fact a resonance phenomenae between the way to small coupling Cap and the
involved inductances, leading to an EQ, to the tune of as much as 3 - 4db at
LF....
One advantage is that a smaller core can be used for the OPT and hence the
OPT will have better HF or be cheaper to make (take your pick). And the PSRR
is better in Parafeed, though it can be equalled in most circuits if we use
cancellation form the HT.
As said before, I cannot percieve either technical or audible advantages
from Parafeed, but there are economical ones....
Later T
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=========================================================================
From: TubeGarden@aol.com
Subject: Re: [JN] Parafeed?
Date: Wed, 18 Oct 2000 07:10:55 EDT
Source: Sound Digest Archive v02.n697
In a message dated 10/18/00 3:02:26 AM US Mountain Standard Time,
AllenVSE@compuserve.com writes:
> Question 1: Why then doesn't a parafeed amp suffer exactly the same "non
> linearity" around the zero crossing point that P-P (supposedly) does?
The DC is holding the choke at flux.
>
> Question 2: If it does have this non linear distortion due to the BH curve,
> what are the theoretical advantages of parafeed that outweigh this and yet
> are not possible in a PP design?
>
It doe not, only A/C passes the output transformer.
One may build a parafeed PP design and reap the benefits.
Whether they are to one's taste is another matter.
I found being able to seriously listen to a $20. output transformer a great
joy, others may be more jaded :)
Happy Ears!
Al B^}
=========================================================================
From: Roscoe Primrose <roscoe@aiko.com>
Subject: Re: [JN] Parafeed?
Date: Wed, 18 Oct 2000 09:18:07 -0400
Source: Sound Digest Archive v02.n697
TubeGarden@aol.com wrote:
>
> In a message dated 10/18/00 3:02:26 AM US Mountain Standard Time,
> AllenVSE@compuserve.com writes:
>
> > Question 1: Why then doesn't a parafeed amp suffer exactly the same "non
> > linearity" around the zero crossing point that P-P (supposedly) does?
>
> The DC is holding the choke at flux.
What, pray tell, does this have to do with the OPT non-linearity at the
zero crossing point?
>
> >
> > Question 2: If it does have this non linear distortion due to the BH curve,
> > what are the theoretical advantages of parafeed that outweigh this and yet
> > are not possible in a PP design?
> >
> It doe not, only A/C passes the output transformer.
Which is precisely why it DOES pass through a very non-linear potion of
the BH curve. If you look at the curves, one of the most non-linear
regions is near zero flux as the field polarity reverses.
Peace
- --
Roscoe Primrose -- mailto:roscoe@aiko.com --
http://www.aiko.com/roscoe
"Once in a while you get shown the light
In the strangest of places if you look at it right." Robert Hunter
"640K ought to be enough for anybody" , Bill Gates, 1981
=========================================================================
From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: RE: [JN] Parafeed?
Date: Wed, 18 Oct 2000 10:58:36 -0400
Source: Sound Digest Archive v02.n697
hi folks,
i am a little confused.
i have heard a number of you say that in a conventional SE
OPT with DC bias, the flux swings thru the most linear portion
of the BH curve.
and that in a PP amp, it has to swing thru a more non-linear
portion of the BH curve.
i think i understand where you are going with this,
but i believe that this statement is fundamentally incorrect
or at least requires clarification.
from a steadt-state perspective,
the BH curve, ignoring hysteresis for the moment, is symmetrical about the
origin. including hysteresis, it is sort of a "mirror image" across the
origin.
so with a *symmetrical* exitation (such as a sine-wave)
a PP opt benefits from being able to swing over a wider
B and H level (-/- quadrant as well as +/+ quadrant).
there is no "zero-crossing" non-linearity as far as the BH curves are
concerned.
and also heep in mind (i think someone else already mentioned)
that in a SE OPT with DC bias, there is a "miniature" BH loop
that the signal follows - inside the major BH loop.
the zero crossing simply occurs about the new bias point.
however, we are not concerned with "steady-state" analyses
when we are talking about a dynamic excitation such as music!
just considering a transient analysis, for now, there is an effect
associated with the "initial magnitization" of the core.
it is assumed that the residual flux in the core is zero,
and the BH trajectory during the first transient begins at the origin. this
trajectory is usually shown as a non-linear path
to the "steady-state" BH curve. it looks like a diode curve
that eventually bends into an "S" to match the bend-over of the BH curve at
high B.
*this* is probably the effect that youse guru must be referring to.
you could imagine that this would repeat on every transient,
like a burst of sine, then rest, then another burst.
during the first sine, the trajectory would follow the "initial
magnetization" curve - at least for a while.
during the rest of the sines, the trajectory would follow the
"normal" BH curve - in a fairly linear fashion.
i suppose there is a comparable "decay" bach to the zero point
when the burst stops - this could be even worse effect [?!?].
real music is *much* more complicated than this simplification.
so who knows what is going on...
now i have to wonder. does this "initial magnetization" effect
go away when you apply a DC bias?
it is easy to assume that it does.
but i am not so sure.
or maybe it still occurs, but the trajectory eminates from the DC operating
point instead of the origin.
what makes the ZERO flux point so special
(as opposed to a particular DC operating point that has been
stable for an appreciable duration)?
and, a lesser point, what makes us think that we can so perfectly balance to
the ZERO flux point, anyway?
i'm sure there is some old text on the subject, and it might be a fun
experiment to observe. but i don't have the time or inclination for this
research. some things are easier to simply accept at face value.
but it's always fun to put some science behind a phenomenon,
rather than accept some mystic hype... ;)
gotta get back to work,
bob.d.
> ----------
> From: Allen Wright[SMTP:AllenVSE@compuserve.com]
> Sent: Wednesday, October 18, 2000 5:56 AM
> To: aJoeNet
> Subject: [JN] Parafeed?
>
> Joes and Joette(s),
> Re Parafeed:
>
> I am not trying to be smart here - Parafeed is strongly recommended by
> some
> serious heavy hitters, yet I have these conflicts:
>
> a/ It is my understanding that one of the generally assumed "problems"
> with
> push-pull topology is that without signal the OPT sits with zero flux
> (assuming the DC standing currents are balanced) and that when some signal
> arrives the OPT must swing through a quite non-linear segment of it's BH
> curve before reaching a more optimum portion. And does this non-linear to
> linear dance on every zero crossing transition of the signal. Yes?
>
> b/ A (conventional) SE amp correctly matched to it's (air-gapped) OPT runs
> a standing current that places it's operating condition right in the
> middle
> of the most linear part of the BH curve area - and in normal operation
> should never swing down (or up) as far as the curved portion the P-P amp
> cannot advoid. Yes?
>
> c/ And this standing current in the OPT is one of the theroretical
> advantages of the SE topology - Yes?
>
> d/ A single ended parafeed amp (normally) is is choke loaded and cap feeds
> an OPT - which doesn't have/need an air gap because it doesn't carry any
> DC
> current. Yes?
>
> Question 1: Why then doesn't a parafeed amp suffer exactly the same "non
> linearity" around the zero crossing point that P-P (supposedly) does?
>
> Question 2: If it does have this non linear distortion due to the BH
> curve,
> what are the theoretical advantages of parafeed that outweigh this and yet
> are not possible in a PP design?
>
> Very curious on these points...
>
> Allen (VSE)
>
>
>
>
>
=========================================================================
From: Thomas Danley <Tom@ppci.com>
Subject: Re: [JN] Parafeed?
Date: Wed, 18 Oct 2000 11:34:57 -0500
Source: Sound Digest Archive v02.n697
"T. Loesch" wrote:
> snip>
>
> It is (IMHO) a problem, but many specifically for parafeed and similar
> operation designed transformers incorporate a certain percentage of "better"
> core material, be it Permalloy, Nickel or MuMetal, all of which reduce the
> distortion.
>
> Later T
> _________________________________________________________________________
Hi
If one looked at the BH curves alone, one would conclude that the material which
had the least magnetic non linearity would be the best (distortion wise) and one
would not want to use square loop materials which has significant magnetic
Hysteresis.
As the non linearity that effects the audio signal is caused by the non linear
magnetizing current, not magnetic non linearity, one can substitute a more non
linear material IF it also has sufficiently high permeability to raise the
impedance of the magnetizing current to offset the more non linear material.
Switching a to a Square Permaloy core, one find that the material is "less
linear" but the permeability is 6-8 times that of sil steel and as the Bmax is
about half, twice the turns per volt are needed. The result is a much higher
inductance and much less magnetizing current..
Although the magnetizing impedance now has more non linearity, its current is
much smaller with respect to the audio signal and so has much less effect on it.
Going the other direction, one might use the same analysis on the effect of an
air gap on linearity (not considering the DC portion). It looks like to me is
that an air gap actually has no effect on the non linear portion of the
magnetizing current
Adding an air gap does lower the magnetic circuit permeability and this lowers
the magnetizing impedance in parallel with the source/load.
Measuring the magnetic circuits non linearity would show a more linear circuit,
how ever since it is the nonlinear impedance related to the source / load that
really matters it is not that simple. The nonlinear current (needed to swing
the core's iron around its Hysteresis loop) is actually unchanged (you have not
changed the core material just added a totally linear air gap in series.
The effect is I think like connecting a totally pure resistance in parallel with
a larger but non linear resistance, the pure resistance does hide the non
linearity but it does not change the magnitude of the non linear part.
Cheers,
Tom Danley
=========================================================================
From: dslagle@earthlink.net (dave slagle)
Subject: Re: [JN] Parafeed?
Date: Wed, 18 Oct 2000 11:59:29 -0400
Source: Sound Digest Archive v02.n697
Dare i get involved with some opinions... oh why not.
>a/ It is my understanding that one of the generally assumed "problems" with
>push-pull topology is that without signal the OPT sits with zero flux
>(assuming the DC standing currents are balanced) and that when some signal
>arrives the OPT must swing through a quite non-linear segment of it's BH
>curve before reaching a more optimum portion. And does this non-linear to
>linear dance on every zero crossing transition of the signal. Yes?
it has been presented to me, and i agree with the idea that the zero
crossing is not an issue at all, the real bugaboo comes with the use of non
gapped transformers...
again.. look at...
<http://albums.photopoint.com/j/View?u=37049&a=237580&p=30886175&Sequence=0&
res=high>
note thatr the gapped core has no opening in the loop, which to me means
the up and down if you will follow the same line. the interleaved core has
a noted opening, which means the up and down follow different paths.. its
the opening of the loop that gives us the alleged distortion, not the zero
crossing... in other words, put a small amount of DC through the
interleaved core to bias it 1/2 way to saturation, you will still get a
minor loop with an opening... so to me the zero crossing is a bit
misleading, the problem comes with that damn open B-H loop.
looking at my curves, the most linear part seems to be at the zero crossing...
>c/ And this standing current in the OPT is one of the theroretical
>advantages of the SE topology - Yes?
i see it as the DC forces you to gap it which gives you a more linear
core... it closes the loop... this is why partridge and crowhurst advocated
gapped PP trannies.
from ironman
>A closing comment:
>
>The same disadvantage of the PP output transformer is present with
>input transformers. Even more so, as these operate at far lower
>signal levels. I never heard a detoriation in sound when I added an
>input trabsformer to a conventinal SE amp.
right... but they use materials like nickel that have a much narrower loop
to begin with... if all this zero crossing were the problem the whole
recording industry would be doomed!.. but somehow they got by...
dave
=========================================================================
From: tube@jump.net
Subject: Re: [JN] Parafeed?
Date: Wed, 18 Oct 2000 12:07:59 -0500
Source: Sound Digest Archive v02.n697
Allen Wright wrote:
> b/ A (conventional) SE amp correctly matched to it's (air-gapped) OPT runs
> a standing current that places it's operating condition right in the middle
> of the most linear part of the BH curve area - and in normal operation
> should never swing down (or up) as far as the curved portion the P-P amp
> cannot advoid. Yes?
I wondered about this for many years, until the following sequence of
thoughts finally hit me. The "zero-crossing" point of the B-H curve is
largely a myth. It exists only when the first note rises; as soon as
the signal reverses direction it dissappears, never to be seen again.
Instead, the signal travels through this non-linear region every single
time the signal reverses direction, no exceptions. A transformer with a
DC flux therefore has an advantage on the first quarter of the first
note, after which, like all other transformers, it must pass through
the non-linear region on every reversal. An "extra" distortion point at
the zero flux point does not exist if the transformer is "coming down"
from a point of higher flux, which you can easily verify by looking at
the usual hysteresis loops.
I think that the effect of all this is to vary the overall inductance
of the transformer at each reversal, with a low initial inductance
changing to a high inductance once it gets past the knee, the non-
linear region. For very high frequency signals this should have little
if any effect, but for low frequency signal it means that the signal
shifts in phase, by quite a lot, at the beginning of each reversal. The
good news here is that the low frequncy signals are also the big
signals, so this effect only occurs at the beginning of each signal.
Now, having said that, is there anything we can do to minimize this? I
am still confused on this subject, but an obvious is to use a material
that has low non-linearity. This will occur if the initial and maximum
permeabilities of the core are fairly close in value, which means that
the inductance will not change much; the material has very little non-
linearity to begin with. The two best "common" materials that I am
aware of are Sendust and 1040 Alloy, with initial and maximum
permeabilities of 30K/120K and 40K/100K respectively, giving them a
4:1 ratio (Sendust) and a 2.5:1 ratio (1040 Alloy) of max. to min.
permeabilities. This may sound like a lot but compare them to materials
like grain-oriented Silicon-Iron, 1.5K/40K, a ratio of 27:1, or 68
Permalloy, 250K/1.2K, a ratio of 208:1! Now that's non-linearity! There
are other materials that have ratios much better than 1040 Alloy, by
the way. I can't find much information on Mike's Cobalt alloy materials
but what I have seen suggests that a ratio of 7:1 or lower is very
possible. Because of the very high expense of Cobalt, I HOPE they sound
terrible, so I can forget about them, but they probably sound fantastic
(I am convinced that God hates Wealth, and finds ever more creative
ways to cause us to part with what little we have ...).
Another big factor, however, is the air-gap. The equations get too
complicated for me, involving core area, length, etc., but a fairly
good simplification is to view them like capacitors, which when added
in series have an overall reduction. If the air-gap has a
"permeability" of 100, then this air-gap plus a steel core of 1.5K/40K
gives an overall of 100 + 1.5K = 93.75 overall, up to 100 + 40K =
99.75, a ratio of min to max permeabilities of just 1.064:1, or about
6.4%. This is obviously so low that we don't have to worry about it,
although the real numbers using the real equations are not quite this
good. Still, we can easily see why an air-gap "linearizes" the magnetic
flux. What confuses me is that Partridge derived all this, but then
went on to say that for some reason, an air-gap results in NO decrease
in distortion. ??? He then went on to say we should include one anyway.
??? I don't have a clue about either of these statements, and I have
about decided to pretend that he never said them, so I can forget about
them.
Other factors exist, however. It may be that, all other things being
equal, the Nickel/Cobalt/other exotic cores sound better due to very
high initial permeabilities, making them more sensitive to the very
small signals, allowing more music to get through. As long as the
initial permeability is quite high--78 Permalloy has 8K/100K, with a
ratio of 12.5:1--a very small air-gap (high permeability) will provide
very low distortion. Here an air-gap of 600, allowing 6 times the
primary inductance of the 100 air-gap of steel, has a ratio of 1.067:1
or about 6.7%.
Overall then, it does sound to me like we still need an air-gap with
parafeed, unless the really, really exotic materials are used, but it
can be a very small air-gap indeed. Parafeed allows us to forget about
the DC limitations of exotic materials. Actually, as long as it has a
very small air-gap, it allows us to forget about EVERYTHING except the
basic nature of the core materials, allowing us to choose them on the
pure basis of "what sounds best", instead of being limited to materials
which can handle high DC current levels, or having to accept a massive
increase in core size, which costs much more and reduces the frequency
range of any transformer.
Phil
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Parafeed?
Date: Wed, 18 Oct 2000 14:53:00 GMT
Source: Sound Digest Archive v02.n697
Hi,
>This sounded good, but had the LF EQ effects, Thorsten
>described. In fact the LF response started to rise below
>40Hz to as much as +6dB at 20Hz. This gave the impression of
>a very good bass response, not unpleasant or phony at all.
>Since my speakers don't go too low this compensated somewhat.
Yes, my take very much as well. Of course, simply increasing the Capacitor
reduces the Pole proportionally out of harms way if that is desired.
>But it had instability problems. Whenever the line voltage
>surged or sagged a litte, there would be an immense low freq
>pulse.
Yes, I do have a reason of using some form of regulation....
>My conclusions out of this (may be valid, may be not):
The Parafeed output Transformers you use, what is the core
material?Grainoriented steel or something freakier?
>Distortion introduced by the BH-nonlinearity of ungapped transformers
>is not very noticable to the human ear ? And this might not really
>be a problem of PP ?
It is (IMHO) a problem, but many specifically for parafeed and similar
operation designed transformers incorporate a certain percentage of "better"
core material, be it Permalloy, Nickel or MuMetal, all of which reduce the
distortion.
Later T
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=========================================================================
From: thomas.mayer@philips.com
Subject: Re: [JN] Parafeed?
Date: Wed, 18 Oct 2000 16:31:26 +0200
Source: Sound Digest Archive v02.n697
Allen, all,
Although I haven't experimented too much with parafeed yet,
and didn't build a PP amp (yet) I have some experience and
thoughts which might be worth sharing.
I have not used parafeed in a power amp, but the two stages
in my phono preamp are parafed. Before switching to parafeed
I had a variant of the so called ultrapath topology in the
phonostage. Ultrapath connects the last B+ bypass cap to the
cathode of the tube instead of ground. While the 'common'
ultrapath has another cap from B+ to ground, I omitted that.
The last cap going to the cathode is directly connected
to the last choke of the PS filter.
This sounded good, but had the LF EQ effects, Thorsten
described. In fact the LF response started to rise below
40Hz to as much as +6dB at 20Hz. This gave the impression of
a very good bass response, not unpleasant or phony at all.
Since my speakers don't go too low this compensated somewhat.
But it had instability problems. Whenever the line voltage
surged or sagged a litte, there would be an immense low freq
pulse.
I guess the primary inductance of the interstage transformer
in series with the coupling cap to the cathode was essentially
a short at the resonant frequency, creating positive feedback
from plate to cathode. Due to the low resonant frequency
(below 10 Hz) this didn't create a sustained LF oscillation.
To get rid of that, I switched to parafeed. coupling cap in
the ground leg, also connected to the cathode, not ground
"ultra-para-feed" "short-parafeed" ? Name it what you want.
Although this still has the problem of the short at the
resonant frequency, the resonance is far lower due to the
much higher primary inductance of the parafeed transformer.
In fact it is out of the frequency band of the phonostage now.
No LF EQ effect any more. Also stable when the line saggs or
surges. the same number of components in the signal path as
before: tube, transformer, cap. The same choke as plate load,
as I used with the gapped transformer (it's a suitable plate
choke). Same cap.
To my surprise those two configurations had very similar
sound characteristics. In fact the only relevant difference
was the lack of stability and EQ effect of the parafeed
solution. many of you have heard this topology in Arhus.
Bear in mind that this is a phonostage, so it's far upstream
the signal path. Sound differences whould be very apparent
My conclusions out of this (may be valid, may be not):
> a/ It is my understanding that one of the generally assumed "problems" with
> push-pull topology is that without signal the OPT sits with zero flux
> (assuming the DC standing currents are balanced) and that when some signal
> arrives the OPT must swing through a quite non-linear segment of it's BH
> curve before reaching a more optimum portion. And does this non-linear to
> linear dance on every zero crossing transition of the signal. Yes?
Distortion introduced by the BH-nonlinearity of ungapped transformers
is not very noticable to the human ear ? And this might not really
be a problem of PP ?
> b/ A (conventional) SE amp correctly matched to it's (air-gapped) OPT runs
> a standing current that places it's operating condition right in the middle
> of the most linear part of the BH curve area - and in normal operation
> should never swing down (or up) as far as the curved portion the P-P amp
> cannot advoid. Yes?
> c/ And this standing current in the OPT is one of the theroretical
> advantages of the SE topology - Yes?
Maybe more of a theoretical (measurable) advantage than an audible ?
> d/ A single ended parafeed amp (normally) is is choke loaded and cap feeds
> an OPT - which doesn't have/need an air gap because it doesn't carry any DC
> current. Yes?
>
> Question 1: Why then doesn't a parafeed amp suffer exactly the same "non
> linearity" around the zero crossing point that P-P (supposedly) does?
The parafeed amp still has the advantage of fewer compionents in
the signal path. Just one tube instead of two, A continues primary
instead a split (and possibly mismatched) one.
> Question 2: If it does have this non linear distortion due to the BH curve,
> what are the theoretical advantages of parafeed that outweigh this and yet
> are not possible in a PP design?
No matching problems ?
A closing comment:
The same disadvantage of the PP output transformer is present with
input transformers. Even more so, as these operate at far lower
signal levels. I never heard a detoriation in sound when I added an
input trabsformer to a conventinal SE amp.
Ciao ... Thomas
=========================================================================
From: David Barnett <d_n_b@swbell.net>
Subject: Re: [JN] Parafeed?
Date: Wed, 18 Oct 2000 13:07:00 -0500
Source: Sound Digest Archive v02.n698
On Wed, 18 Oct 2000 10:22:25 +0000 (GMT), "T. Loesch"
<ezee_e@hotmail.com> wrote:
>I commented before that IMHO much of the "improved bass" with parafeed is in
>fact a resonance phenomenae between the way to small coupling Cap and the
>involved inductances, leading to an EQ, to the tune of as much as 3 - 4db at
>LF....
I've always wondered about the wisdom of replacing one reactance with
three...
- --dnb
=========================================================================
From: Paul Joppa <pdjoppa@home.com>
Subject: Re: [JN] Parafeed?
Date: Thu, 19 Oct 2000 01:17:59 -0700
Source: Sound Digest Archive v02.n699
Hi all-
Sorry I came into this late. Fortunately I read the next two digests, so
a lot of what I wanted to say has already been said. To the best of my
knowledge, Bob Danielak and Tom Danley have described the situation
pretty well. I'll throw in my support of their comments below, in answer
to Allen Wright's questions.
> a/ It is my understanding that one of the generally assumed "problems" with
> push-pull topology is that without signal the OPT sits with zero flux
> (assuming the DC standing currents are balanced) and that when some signal
> arrives the OPT must swing through a quite non-linear segment of it's BH
> curve before reaching a more optimum portion. And does this non-linear to
> linear dance on every zero crossing transition of the signal. Yes?
This is a bogus "problem". Push-pull does not suffer from any such
magnetic difficulty; it is a confusion based on the common practice of
magnetic textbooks, which describe what happens when you start from a
completely demagnetized material in order to explain the hysteresis
loop. As soon as the music starts, the transformer no longer sits at
zero flux even during the quiet passages; it has a history. Unless it is
carefully demagnetized, it will never again start from zero. You can
hear this with parafeed amps (those that do not incorporate protection
from startup transients) - they are magnetized by the startup transient,
and often must play music for an hour or so before they sound "right" -
that is, the music acts as a partial demagnetizing signal.
> b/ A (conventional) SE amp correctly matched to it's (air-gapped) OPT runs
> a standing current that places it's operating condition right in the middle
> of the most linear part of the BH curve area - and in normal operation
> should never swing down (or up) as far as the curved portion the P-P amp
> cannot advoid. Yes?
No, that's another misunderstanding. For small signals, the local
nonlinearity and hysteresis look the same no matter what the DC bias (as
long as it is well away from saturation). For large signals, a DC biased
transformer will saturate on positive peaks but not on negative ones, so
a too-small transformer will have overload (saturation) distortion that
has more even harmonics and less odd harmonics if it is DC biased. But
if the transformer is designed so that it never enters saturation in
normal operation, the distortion is the same whether there is DC bias or
not.
> c/ And this standing current in the OPT is one of the theroretical
> advantages of the SE topology - Yes?
No, it's another myth. There is a grain of truth in it, though. If a
transformer is airgapped to handle the DC, it may be larger and have
more turns in order to restore some of the inductance lost to the air
gap. Since the distortion depends on the core (not the air gap), this
larger core with more turns will have less distortion. But that's
because the core is bigger, not because it is air gapped or has DC in
it. A push-pull transformer on the same large core with the same number
of turns will have the same reduced distortion.
> d/ A single ended parafeed amp (normally) is is choke loaded and cap feeds
> an OPT - which doesn't have/need an air gap because it doesn't carry any DC
> current. Yes?
Yes.
> Question 1: Why then doesn't a parafeed amp suffer exactly the same "non
> linearity" around the zero crossing point that P-P (supposedly) does?
As above, there is no such excess nonlinearity mechanism, and neither
parafeed not push-pull amps suffer from it.
> Question 2: If it does have this non linear distortion due to the BH curve,
> what are the theoretical advantages of parafeed that outweigh this and yet
> are not possible in a PP design?
The theoretical advantages of parafeed are basically the same as
push-pull, the linear range (without saturation) of the output
transformer is larger so the transformer can be smaller. It's an
incidental advantage that with a smaller transformer the leakage
inductance is smaller, so less interleaving is necessary to obtain a
satisfactory bandwidth, and therefor the leakage capacitance can be kept
small. The real (still theoretical) advantage is the smaller
transformer. In the old days, this was very important for AM
transmitters, which used a DC-carrying transformer to modulate the RF
output stage. The total amount of iron required to meet a given power
and bandwidth requirement is much less for parafeed than for a single
airgapped transformer. Reuben Lee has a clear discussion of this,
including photographs of transmitters built to the same specs using both
philosophies - the size difference is staggering. This appears in the
second edition of "Electronic Transformers and Circuits", but does not
appear in the third edition - apparently by 1988 this information had
become irrelevant.
Now for high fidelity use, push-pull has the same advantage as parafeed
(ignoring for the moment the power supply isolation issue). In both
cases the output transformers are smaller for the same power and iron
distortion requirement. The other differences are not due to the
transformer. And note that push-pull has a similar power supply
isolation advantage as parafeed; both are superior in that sense to
"normal" airgapped SE amp designs. My ears still prefer SE sound over
push-pull, but it is not for either magnetic hysteresis or power supply
isolation reasons.
Well, that's my input. This is not the first time I have posted about
this issue, though it's probably the most extensive one. I hope it is
useful.
- -Paul Joppa
=========================================================================
From: thomas.mayer@philips.com
Subject: Re: [JN] Parafeed?
Date: Thu, 19 Oct 2000 09:33:21 +0200
Source: Sound Digest Archive v02.n699
> The Parafeed output Transformers you use, what is the core
> material?Grainoriented steel or something freakier?
It's the Jensen JT-10K61-1M 4:1 line output. According to Jensen
it's a 80% Nickel core.
Thomas
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Parafeed?
Date: Thu, 19 Oct 2000 11:14:28 GMT
Source: Sound Digest Archive v02.n699
Hi Thomas,
>It's the Jensen JT-10K61-1M 4:1 line output. According to Jensen
>it's a 80% Nickel core.
See, try getting such a Transformer on a normal Iron core, not gapped and
listen in horror how bad this CAN be....
Comparative tests can only really attract any claim to general applicability
of the results if "All Else is EQUAL!".... Changing the core material
changes the conditions of the experiment.
Later T
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=========================================================================
From: Dan Marshall <mdaniel7@uswest.net>
Subject: Re: [JN] Parafeed?
Date: Thu, 19 Oct 2000 06:12:16 +0000
Source: Sound Digest Archive v02.n700
Paul Joppa wrote:
>
> Hi all-
<big snip>
> My ears still prefer SE sound over push-pull, but it is not
> for either magnetic hysteresis or power supply isolation reasons.
Why is it then? I am not disagreeing with you, for I also prefer the
sound of SE over PP, but am not fully convinced that I have heard valid
reasons why SE sounds better, nor do I claim to fully understand why.
A while back I was pontificating about a modified PP circuit I dubbed
Quasi-SE which consisted of driving only one output tube grid of a
cathode-biased PP amp with the cathode bypass cap removed. In this case
the "other" output tube receives its drive (phase inverted) from the
cathode of the first (driven) output tube. Examining the distortion
spectrum reveals that such a configuration does indeed produce a
distortion spectrum quite similar to a SE amp.
I recently conducted a listening test to see whether Quasi SE sounds
like a SE amp. The short answer is that it doesn't. The test was
conducted with a Heath AA-71 amp, which is the later, black-chassis
version of the W4-M amplifier, a PP Williamson design using PP 5881s and
a pair of 6SN7s, both Sylvania chrome domes (which reportedly rate high
in the comparative 6SN7 listening tests). I had checked it out
thoroughly to assure it was in proper operating condition, replete with
having examined the distortion spectrum of both PP and Quasi SE
connection.
With the output stage cathode bypass capacitor and one end of one of the
output stage coupling caps disconnected, I listened to it with that
coupling cap making connection and without (i.e., in Quasi SE and PP).
Though the harmonic distortion spectrum was decidedly different in Quasi
SE, I could not discern any difference whatsoever in the way it
sounded. Neither connection sounded as good as a true SE amp. So, that
sort of shoots down the argument that that SE amps sound better because
they produce a distortion spectrum which the ear prefers, nor do I buy
the argument that it is because of poor phase inversion. Phase
inversion can be accomplished with a high degree of precision at audio
frequencies. I still do not fully comprehend why SE sounds better than
PP. And then, there are those who argue that SE doesn't sound better.
Some have said that Allen Wright's PP design is quite good, though I
have never heard it. So I guess I am still in the dark. Perhaps the
Quasi SE/PP listening comparison should be conducted with a triode, no
feedback amp.
Dan Marshall
<snip>
>
> -Paul Joppa
=========================================================================
From: Allen Wright <AllenVSE@compuserve.com>
Subject: Re: [JN] Parafeed?
Date: Thu, 19 Oct 2000 08:05:37 -0400
Source: Sound Digest Archive v02.n700
Various people wrote good and clear answers to my puzzles on SE, PP and
Parafeed.
Thank you all!
Allen (VSE)
=========================================================================
From: "BobC" <bobcx@bellatlantic.net>
Subject: Re: [JN] Parafeed?
Date: Thu, 19 Oct 2000 08:53:23 -0400
Source: Sound Digest Archive v02.n700
- ----- Original Message -----
From: "Allen Wright" <AllenVSE@compuserve.com>
To: "aJoeNet" <sound@lists.io.com>
Sent: Thursday, October 19, 2000 8:05 AM
Subject: Re: [JN] Parafeed?
> Various people wrote good and clear answers to my puzzles on SE, PP and
> Parafeed.
>
> Thank you all!
>
> Allen (VSE)
Allen,
There is some more worthwhile information on this very subject on the SET
forum. Here is a link. http://www.audioasylum.com/forums/SET/bbs.html
This is the thread: ( I don't know nothin' 'bout transformers, but...)
take care
Bob
=========================================================================
From: TubeGarden@aol.com
Subject: Re: [JN] Parafeed?
Date: Thu, 19 Oct 2000 09:06:47 EDT
Source: Sound Digest Archive v02.n700
In a message dated 10/19/00 1:24:38 AM US Mountain Standard Time,
pdjoppa@home.com writes:
> Now for high fidelity use, push-pull has the same advantage as parafeed
> (ignoring for the moment the power supply isolation issue). In both
> cases the output transformers are smaller for the same power and iron
> distortion requirement. The other differences are not due to the
> transformer.
Greets!
Thank you for the information :)
I will try parafeed again when Steve Bench figures out how to do it without a
cap :)
Happy Ears!
Al B^}
=========================================================================
From: "BobC" <bobcx@bellatlantic.net>
Subject: Re: [JN] Parafeed?
Date: Thu, 19 Oct 2000 10:39:45 -0400
Source: Sound Digest Archive v02.n700
- ----- Original Message -----
From: "Paul Joppa" <pdjoppa@home.com>
To: <sound@lists.io.com>
Sent: Thursday, October 19, 2000 4:17 AM
Subject: Re: [JN] Parafeed?
> Hi all-
> SNIP<
Thanks for the excellent post Paul.
Bob
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: RE: [JN] Parafeed?
Date: Thu, 19 Oct 2000 13:37:50 GMT
Source: Sound Digest Archive v02.n700
Hi there,
>I agree that the difference in sound after the first 3/4 hour is something
>to hear. The amp goes from distant, vieled and compressed, then comes alive
>like some sleeping giant.
Funny. My system is of the "just switch it on and play music".... Once
operating points have stabilised (around 5min) it plays music as cleanly,
sweetly and so on as it will after 10 Hours....
Later T
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=========================================================================
From: David Home <David_Home@creoscitex.com>
Subject: RE: [JN] Parafeed?
Date: Thu, 19 Oct 2000 14:44:01 +0200
Source: Sound Digest Archive v02.n700
Paul Joppa wrote:
>You can
>hear this with parafeed amps (those that do not incorporate protection
>from startup transients) - they are magnetized by the startup transient,
>and often must play music for an hour or so before they sound "right" -
>that is, the music acts as a partial demagnetizing signal.
Hi Paul.
I remember John Cammile(sp?) putting a shorting relay across the primary of the nickel output to pre
vent this problem at start up. I thought at the time though, in the big picture of amp warm up, if t
he need is really there. I have BG caps in my pre-amp, tubes in the phono amp & pre-amp, etc that al
so need time to open up. I decided that dealing with this problem of magnetization would not really
improve my musical enjoyment enough to justify the needed parts and work. I agree that the differenc
e in sound after the first 3/4 hour is something to hear. The amp goes from distant, vieled and comp
ressed, then comes alive like some sleeping giant.
Now I certainly could be rationalizing to justify my laziness, and would like your comments. If I ca
n get to good listening within 15 minutes rather then 40, then the work is worthwhile. In your opini
on, is the magnetization the principle bottleneck?
Regards, David
- -----Original Message-----
From: Paul Joppa [mailto:pdjoppa@home.com]
Sent: Thursday, October 19, 2000 10:18 AM
To: sound@lists.io.com
Subject: Re: [JN] Parafeed?
Hi all-
Sorry I came into this late. Fortunately I read the next two digests, so
a lot of what I wanted to say has already been said. To the best of my
knowledge, Bob Danielak and Tom Danley have described the situation
pretty well. I'll throw in my support of their comments below, in answer
to Allen Wright's questions.
> a/ It is my understanding that one of the generally assumed "problems" with
> push-pull topology is that without signal the OPT sits with zero flux
> (assuming the DC standing currents are balanced) and that when some signal
> arrives the OPT must swing through a quite non-linear segment of it's BH
> curve before reaching a more optimum portion. And does this non-linear to
> linear dance on every zero crossing transition of the signal. Yes?
This is a bogus "problem". Push-pull does not suffer from any such
magnetic difficulty; it is a confusion based on the common practice of
magnetic textbooks, which describe what happens when you start from a
completely demagnetized material in order to explain the hysteresis
loop. As soon as the music starts, the transformer no longer sits at
zero flux even during the quiet passages; it has a history. Unless it is
carefully demagnetized, it will never again start from zero. You can
hear this with parafeed amps (those that do not incorporate protection
from startup transients) - they are magnetized by the startup transient,
and often must play music for an hour or so before they sound "right" -
that is, the music acts as a partial demagnetizing signal.
> b/ A (conventional) SE amp correctly matched to it's (air-gapped) OPT runs
> a standing current that places it's operating condition right in the middle
> of the most linear part of the BH curve area - and in normal operation
> should never swing down (or up) as far as the curved portion the P-P amp
> cannot advoid. Yes?
No, that's another misunderstanding. For small signals, the local
nonlinearity and hysteresis look the same no matter what the DC bias (as
long as it is well away from saturation). For large signals, a DC biased
transformer will saturate on positive peaks but not on negative ones, so
a too-small transformer will have overload (saturation) distortion that
has more even harmonics and less odd harmonics if it is DC biased. But
if the transformer is designed so that it never enters saturation in
normal operation, the distortion is the same whether there is DC bias or
not.
> c/ And this standing current in the OPT is one of the theroretical
> advantages of the SE topology - Yes?
No, it's another myth. There is a grain of truth in it, though. If a
transformer is airgapped to handle the DC, it may be larger and have
more turns in order to restore some of the inductance lost to the air
gap. Since the distortion depends on the core (not the air gap), this
larger core with more turns will have less distortion. But that's
because the core is bigger, not because it is air gapped or has DC in
it. A push-pull transformer on the same large core with the same number
of turns will have the same reduced distortion.
> d/ A single ended parafeed amp (normally) is is choke loaded and cap feeds
> an OPT - which doesn't have/need an air gap because it doesn't carry any DC
> current. Yes?
Yes.
> Question 1: Why then doesn't a parafeed amp suffer exactly the same "non
> linearity" around the zero crossing point that P-P (supposedly) does?
As above, there is no such excess nonlinearity mechanism, and neither
parafeed not push-pull amps suffer from it.
> Question 2: If it does have this non linear distortion due to the BH curve,
> what are the theoretical advantages of parafeed that outweigh this and yet
> are not possible in a PP design?
The theoretical advantages of parafeed are basically the same as
push-pull, the linear range (without saturation) of the output
transformer is larger so the transformer can be smaller. It's an
incidental advantage that with a smaller transformer the leakage
inductance is smaller, so less interleaving is necessary to obtain a
satisfactory bandwidth, and therefor the leakage capacitance can be kept
small. The real (still theoretical) advantage is the smaller
transformer. In the old days, this was very important for AM
transmitters, which used a DC-carrying transformer to modulate the RF
output stage. The total amount of iron required to meet a given power
and bandwidth requirement is much less for parafeed than for a single
airgapped transformer. Reuben Lee has a clear discussion of this,
including photographs of transmitters built to the same specs using both
philosophies - the size difference is staggering. This appears in the
second edition of "Electronic Transformers and Circuits", but does not
appear in the third edition - apparently by 1988 this information had
become irrelevant.
Now for high fidelity use, push-pull has the same advantage as parafeed
(ignoring for the moment the power supply isolation issue). In both
cases the output transformers are smaller for the same power and iron
distortion requirement. The other differences are not due to the
transformer. And note that push-pull has a similar power supply
isolation advantage as parafeed; both are superior in that sense to
"normal" airgapped SE amp designs. My ears still prefer SE sound over
push-pull, but it is not for either magnetic hysteresis or power supply
isolation reasons.
Well, that's my input. This is not the first time I have posted about
this issue, though it's probably the most extensive one. I hope it is
useful.
- -Paul Joppa
=========================================================================
From: Christian Rintelen <christian@rintelen.ch>
Subject: [JN] parafeed and cap sizes
Date: Mon, 23 Oct 2000 13:05:56 +0200
Source: Sound Digest Archive v02.n705
Thorsten Loesch wrote about his para-fedup experience:
> Coupling Capacitor was 22uF Ansar Supersound.
>
The large cap values needed for fullrange parafeed have always bothered me. Of
course it is possible to build a good sounding 22 uF cap. But it's easier to
build a good 2.2 uF cap. And it's even easier to build a good 0.22 uF cap. I
hope you get the drift...
You'd want a cap to store and release energy as fast as possible. I don't know
if it's correct to do so, but I'd like to compare caps with muscles. Imagine a
big and a small muscle that can "store" (or release) the same amount of energy.
I'd bet that the smaller muscle with the higher "energy per fibre" coefficient
will release the energie faster and more "explosive" than the bigger muscle.
Now take a 100 uF polyprop cap and a 100 uF tantalum cap, both of course with
the same voltage rating. The poly will inevitably be huge, whilst the tantalum
can be built very small. Has anybody ever measured how fast the two caps can
release the same amount of energy (joules, volts - whatever you want)? (I
haven't - it's not a rhetorical question!)
Please note: I'm NOT talking about how a polyprop and a tantalum cap sound in
that specific use, just how fast they can store and/or release energy.
Christian
PS. If you want to witness the density of the stored energy, just reverse the
polarity on a tantalum cap... DON'T DO THIS AT HOME, KIDS - the mess is
tremendous and the bang fare more impressive than with a conventional
electrolytic cap of the same capacity! (I was very lucky to wear glasses when
it happened to me. 'nuff said.)
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] parafeed and cap sizes
Date: Mon, 23 Oct 2000 14:24:03 GMT
Source: Sound Digest Archive v02.n705
Hi all,
>The large cap values needed for fullrange parafeed have always bothered me.
Well, in classic SE the final PSU Filter Cap and the Cathode Bypass Cap (if
used) are needed to complete the AC current loop. So what you are happy to
use as PSU Cap will be equally fine as Parafeed Cap... ;-)
Later T
PS, blowing up Cap's is way more fun with the Huge (say 47,000uF 40V) Can
Capacitors and a Variac. Almost like a handgranade. Best keep it outside the
house. We one blew a hole into a roof blowing one of these up.
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From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] parafeed and cap sizes
Date: Mon, 23 Oct 2000 15:10:22 GMT
Source: Sound Digest Archive v02.n705
Hi all,
>In both versions it is possible to use the ultrapath "trick"
>which feeds the signal path to the cathode directly and thus
>bypassing cathode resistor/cap combination.
Even better. If, in the classic SE Circuit the additional "Ultrapth"
Capacitor is sized suitably (Ck / 1+Mu) we achive around 20db better PSRR
and have a current loop that is equally short.
>Since the parafeed circuit is better isolated from the PS through
>the plate load choke, can we assume that the cap in the B+ has
>less influence on the sound ? Opinions ?
Yup, agreed. A correctly tuned "Ultrapath with Cathode bypass cap" classic
SE Circuit allows the same though.
>I came to the conclusion, that parafeed has just as many parts in the
>signal path.
Almost yes, the Anode load choke comes into the signal path and is extra.
Later T
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From: thomas.mayer@philips.com
Subject: Re: [JN] parafeed and cap sizes
Date: Mon, 23 Oct 2000 15:12:02 +0200
Source: Sound Digest Archive v02.n705
Christian,
> The large cap values needed for fullrange parafeed have always bothered me.
In a "regular" circuit with DC in the transformer, you
have a cap in the signal path which is just as large.
That's the last cap in your power supply.
While the signal loop goes through tube, coupling cap, transformer,
cathode resistor + bypass cap with parafeed, with conventional
circuits it sees: tube, transformer, B+ cap, cathode resistor +
bypass cap. Very similar.
In both versions it is possible to use the ultrapath "trick"
which feeds the signal path to the cathode directly and thus
bypassing cathode resistor/cap combination.
Since the parafeed circuit is better isolated from the PS through
the plate load choke, can we assume that the cap in the B+ has
less influence on the sound ? Opinions ? My experience shows
exactly this. I came to the conclusion, that parafeed has just as
many parts in the signal path.
Ciao ... Thomas
=========================================================================
From: "Sikking, Peter" <peter.sikking@nomura.co.uk>
Subject: RE: [JN] parafeed and cap sizes
Date: Mon, 23 Oct 2000 15:17:15 +0100
Source: Sound Digest Archive v02.n705
Christian wrote:
- --Thorsten wrote:
> Coupling Capacitor was 22uF Ansar Supersound.
- --The large cap values needed for fullrange parafeed have
always bothered me.
I maybe wrong, but every time I compare PF stages to series fed stages
I notice that not, like a lot of people moan about, a cap has been added,
but just moved position, from a decoupling (SF) to a coupling (PF) position.
Now I would like to bet that for any given amp-builder:
minimum decoupling (SF) cap >= maximum coupling (PF) cap
And like you say, the smaller the cap, the higher the chance of getting
some quality.
Later,
--Peter
: music lover : ultra-fi builder : ui designer & developer : on drums...
: from:amsterdam@london.uk : +44 20 7521 1070 : facsimile +44 20 7521 3686
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=========================================================================
From: "Sikking, Peter" <peter.sikking@nomura.co.uk>
Subject: RE: [JN] parafeed and cap sizes
Date: Mon, 23 Oct 2000 16:56:42 +0100
Source: Sound Digest Archive v02.n705
T wrote:
- --Even better. If, in the classic SE Circuit the additional "Ultrapth"
Capacitor is sized suitably (Ck / 1+Mu)[...]
It's Ck/mu.
The "+ 1" for kathode amplification falls out of the equation for maximum
PSRR if you solve it.
Still testing this set-up at home. Starting to think that it sounds
a bit to much like AC feedback to me. I may be wrong...
(Thomas:)
> I came to the conclusion, that parafeed has just as many
parts in the signal path.
- --Almost yes, the Anode load choke comes into the signal path
and is extra.
I'd like to think more that one swaps a PS choke & decoupling cap (SF)
for a plate choke and coupling cap (PF) combo.
--Peter
: music lover : ultra-fi builder : ui designer & developer : on drums...
: from:amsterdam@london.uk : +44 20 7521 1070 : facsimile +44 20 7521 3686
PLEASE READ: The information contained in this e-mail is confidential
and intended for the named recipient(s) only. If you are not an intended
recipient of this email you must not copy, distribute or take any
further action in reliance on it and you should delete it and notify the
sender immediately. Email is not a secure method of communication and
Nomura International plc cannot accept responsibility for the accuracy
or completeness of this message or any attachment(s). Please check this
e-mail for virus infection, for which Nomura International plc accepts
no responsibility. If verification of this email is sought then please
request a hard copy. Unless otherwise stated any views or opinions
presented are solely those of the author and do not represent those of
Nomura International plc. This email is intended for informational
purposes only and is not a solicitation or offer to buy or sell
securities or related financial instruments. Nomura International plc is
regulated by the Securities and Futures Authority Limited and is a
member of the London Stock Exchange.
=========================================================================
From: ToobWiz@aol.com
Subject: [JN] Parafeed with a ressitor as plate load
Date: Sun, 30 Sep 2001 10:09:42 EDT
Source: Sound Digest Archive v02.n986
Has anyone tried this? I've so completely associated parafeed with the
existence of a choke (or CCS) as the plate load that I never considered the
simple resistor. Just now, I was looking through the first few pages of my
RDH3 (1941) and the expample of parafeed shown uses a resistor.
now, I'm aware that the choke has better performance in both AC and DC
regimes than a resistor. However, that comes at a high price. It is at times
easy to provide the much greater B+ to equalize the DC performance, but then
what about the AC performance?
What really counts is "How does it sound?" and it is not rare that we find
something which sounds better than theory says "it should" (this is
technically known as the "Al Marcy Effect" :-)
I can visualize a really cheap parafeed SET using an R as a load and a PP OPT
or an autoformer.
????
Cheers/Carron
=========================================================================
From: ToobWiz@aol.com
Subject: Re: [JN] Parafeed with a ressitor as plate load
Date: Sun, 30 Sep 2001 12:47:23 EDT
Source: Sound Digest Archive v02.n986
In a message dated 09/30/2001 12:<BR27:<BR08 PM
Eastern Daylight, hifi@ishoejby.dk writes:
> Yes why not. I have made the same thought, but all were using chokes, so
no...
>
> I dropped the idea, but still have a set of output transformer without
airgap
> that could use a coupling like that.
>
> Any suggestions are welcome.
Jan,
this certainly would work, and would work well technically. My only question
is "How would it sound?"
To do it, one would need to have enough B+ so that the voltage remaining at
the output valve, after subtracting the drop across the load resistor, would
be great enough to allow the chosen operating point.
So, say you wanted to poerate a 2A3 at 270vDC and 60 mA. If your load
resistor is 5K, then you'd drop 300v and therefore require a 570vDC supply.
Now, I don't know that 5K is sufficient load to permit full voltage swing of
the output valve, so maybe you should just try it... or, if you have a much
greater B+ available, use a larger resistor. The OPT is protected against the
high B+ (assuming the parafeed cap is it the top of the OPT), but you would
have to use a standby switch *for sure* to prevent the B+ appearing at the
anode before the filament had warmed.
I'd hope that some of the *real* tube wizards would chime in here to provide
additional cautions and technical details that I might have missed.
It is a really cheap topology, so should be worth a try. I'm surprised that
our good pal Al hasn't already tried it this morning. He seems capable of
(and inclined to) making a new amp every hour :-)
Cheers/Don
=========================================================================
From: SBench@aol.com
Subject: Re: [JN] Parafeed with a ressitor as plate load
Date: Sun, 30 Sep 2001 13:56:36 EDT
Source: Sound Digest Archive v02.n986
In a message dated 01-09-30 12:54:47 EDT, ToobWiz@aol.com writes:
>
> this certainly would work, and would work well technically. My only
question
>
> is "How would it sound?"
>
>
Sounds wonderful. My favorite configuration is 801 / 10k resistor capacitively
coupled to the OPT. 300 volts plate to "cathode", 300 volts drop in the
resistor.
- -Steve
=========================================================================
From: "John Levreault" <jlevro@mediaone.net>
Subject: Re: [JN] Parafeed with a ressitor as plate load
Date: Sun, 30 Sep 2001 15:42:14 -0400
Source: Sound Digest Archive v02.n986
My only concern, and it's only on technical grounds, is that the reflected
output load will now be in parallel with this plate load resistor. So if you
had your 801 cap-coupled to a 10K output tranny, the tube would be seeing
5K. This is where parafeed works out "better" from a technical perspective.
This is less of a concern with a driver stage, since the cap-coupled IT is
usually left unloaded, or very lightly.
In addition, the path back to the power supply is now a resistor instead of
the more-usually-employed choke, so the power supply rejection will be
lower. Many cite this as one of the advantages of parafeed. I just think you
need to be more carefuly with your power supply.
But if it sounds good, then do it!
JL
- ----- Original Message -----
From: <SBench@aol.com>
To: <ToobWiz@aol.com>; <hifi@ishoejby.dk>
Cc: <sound@lists.io.com>
Sent: Sunday, September 30, 2001 1:56 PM
Subject: Re: [JN] Parafeed with a ressitor as plate load
> In a message dated 01-09-30 12:54:47 EDT, ToobWiz@aol.com writes:
>
> >
> > this certainly would work, and would work well technically. My only
> question
> >
> > is "How would it sound?"
> >
> >
>
> Sounds wonderful. My favorite configuration is 801 / 10k resistor
capacitively
> coupled to the OPT. 300 volts plate to "cathode", 300 volts drop in the
> resistor.
>
> -Steve
=========================================================================
From: Jan Nielsen <hifi@ishoejby.dk>
Subject: Re: [JN] Parafeed with a ressitor as plate load
Date: Sun, 30 Sep 2001 18:24:35 +0200
Source: Sound Digest Archive v02.n986
Yes why not. I have made the same thought, but all were using chokes, so no...
I dropped the idea, but still have a set of output transformer without airgap
that could use a coupling like that.
Any suggestions are welcome.
Regards,
Jan
ToobWiz@aol.com wrote:
> Has anyone tried this? I've so completely associated parafeed with the
> existence of a choke (or CCS) as the plate load that I never considered the
> simple resistor. Just now, I was looking through the first few pages of my
> RDH3 (1941) and the expample of parafeed shown uses a resistor.
>
> now, I'm aware that the choke has better performance in both AC and DC
> regimes than a resistor. However, that comes at a high price. It is at times
> easy to provide the much greater B+ to equalize the DC performance, but then
> what about the AC performance?
>
> What really counts is "How does it sound?" and it is not rare that we find
> something which sounds better than theory says "it should" (this is
> technically known as the "Al Marcy Effect" :-)
>
> I can visualize a really cheap parafeed SET using an R as a load and a PP OPT
> or an autoformer.
>
> ????
>
> Cheers/Carron
=========================================================================
From: alan cameron <alan@thehub.com.au>
Subject: Re: [JN] Parafeed with a ressitor as plate load
Date: Mon, 1 Oct 2001 19:26:38 +1000
Source: Sound Digest Archive v02.n986
At 10:09 -0400 30/9/01, ToobWiz@aol.com wrote:
>What really counts is "How does it sound?" and it is not rare that we find
>something which sounds better than theory says "it should" (this is
>technically known as the "Al Marcy Effect" :-)
>
>I can visualize a really cheap parafeed SET using an R as a load and a PP OPT
>or an autoformer.
Don, Joes,
I tried this comparison in a stage to driving a phase splitter tranny
with the high mu section of a 6EA7. on the sound front it was no
contest; the iron sounded *much* better even when using an old TV
vertical output tranny as the choke.
I've got no idea how it measured; theoretically the bass should have
been grossly curtailed by the limited inductance of the VOT. it just
sounded better, with surprisingly adequate bass.
alan
- --
=========================================================================
From: James Melhuish <james@melhuish.org>
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Thu, 23 Mar 2000 10:37:03 -0500
Source: Sound Digest Archive v02.n492
Hi Thorsten,
Your suggestion appears (to me) to be similar to Jack Elliano's
Ultrapath setup. See the schematic on the Xdrive (ultrapre.gif). He
ties a 35 to 50 uF oil cap from the bottom of the OPT directly to the
cathode. This return signal path bypasses the power supply entirely
(and the cathode bypass cap). He claims great sound from this. So it's
been done, no?
James
- --
James Melhuish
mailto:james@melhuish.org
http://melhuish.org
=========================================================================
From: David Home <DHome@creo.com>
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Thu, 23 Mar 2000 10:22:15 -0800
Source: Sound Digest Archive v02.n493
I tried the ultra path trick on my #26 transformer coupled line amp.
Resulted in nasty NASTY buzz. Maybe with a indirectly heated cathode you can
get away with not having the filament AC tied to ground, but in particular
case it was bad. I put my BG back in and can live with its character for
now.
Regards, David
-----Original Message-----
From: T. Loesch [mailto:ezee_e@hotmail.com]
Sent: Thursday, March 23, 2000 8:57 AM
To: james@melhuish.org; sound@lists.io.com
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Hi there,
>Your suggestion appears (to me) to be similar to Jack Elliano's
>Ultrapath setup. See the schematic on the Xdrive (ultrapre.gif).
Yes. It is. I have seen it practiced before in old radios and amplifiers
too.
>So it's been done, no?
Yes. We tried it with a 417A Transformer couled Pre.... We lost a quite a
nice Black Gate Cap.... The Improvemnet was neither subtle or ambigous.... I
hate electrolity Cap's. Even Black Gates and the better Elna's....
Then again, I prefer my custom Polyprop Cap in Aluminum Can's and potted
(deals with microphonics in cap's very effectively) over PIO.... But that's
a matter of taste.
Later T
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From: David Home <DHome@creo.com>
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Thu, 23 Mar 2000 13:44:01 -0800
Source: Sound Digest Archive v02.n493
I use CCS heating as well and love it. However the filament needs to be AC
reference tied to ground through a cap or AC/DC coupled by using a fixed
bias on the grid.
Sorry if I was not clear. Regards, David
-----Original Message-----
From: T. Loesch [mailto:ezee_e@hotmail.com]
Sent: Thursday, March 23, 2000 10:51 AM
To: DHome@creo.com; james@melhuish.org; sound@lists.io.com
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Hi there,
>I tried the ultra path trick on my #26 transformer coupled line amp.
>Resulted in nasty NASTY buzz. Maybe with a indirectly heated cathode
>you can get away with not having the filament AC tied to ground, but in
>particular case it was bad. I put my BG back in and can live with its
>character for now.
I have given up using AC heating with DH Valves.
I simply cannot get what I consider sufficiently low noise.... In my books
that is << 1mV on the Output of the Poweramp, Volume control at "normal
clipping level", MC Phono Input selected.
With DC (Constant Current Source Filaments), no problems.
Later Thorsten
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=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Thu, 23 Mar 2000 16:57:28 GMT
Source: Sound Digest Archive v02.n493
Hi there,
>Your suggestion appears (to me) to be similar to Jack Elliano's
>Ultrapath setup. See the schematic on the Xdrive (ultrapre.gif).
Yes. It is. I have seen it practiced before in old radios and amplifiers
too.
>So it's been done, no?
Yes. We tried it with a 417A Transformer couled Pre.... We lost a quite a
nice Black Gate Cap.... The Improvemnet was neither subtle or ambigous.... I
hate electrolity Cap's. Even Black Gates and the better Elna's....
Then again, I prefer my custom Polyprop Cap in Aluminum Can's and potted
(deals with microphonics in cap's very effectively) over PIO.... But that's
a matter of taste.
Later T
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=========================================================================
From: TubeGarden@aol.com
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Thu, 23 Mar 2000 17:34:26 EST
Source: Sound Digest Archive v02.n493
In a message dated 3/23/00 12:00:15 PM US Mountain Standard Time,
ezee_e@hotmail.com writes:
> I have given up using AC heating with DH Valves.
Greets Jeets Neets!
I only use AC on the rectifier filaments.
No sense of adventure :)
Happy Ears!
Al B^}
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Thu, 23 Mar 2000 18:51:01 GMT
Source: Sound Digest Archive v02.n493
Hi there,
>I tried the ultra path trick on my #26 transformer coupled line amp.
>Resulted in nasty NASTY buzz. Maybe with a indirectly heated cathode
>you can get away with not having the filament AC tied to ground, but in
>particular case it was bad. I put my BG back in and can live with its
>character for now.
I have given up using AC heating with DH Valves.
I simply cannot get what I consider sufficiently low noise.... In my books
that is << 1mV on the Output of the Poweramp, Volume control at "normal
clipping level", MC Phono Input selected.
With DC (Constant Current Source Filaments), no problems.
Later Thorsten
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From: =?iso-8859-1?q?Josef=20Aigner?= <josef_aigner@yahoo.com>
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Thu, 23 Mar 2000 23:50:37 -0800 (PST)
Source: Sound Digest Archive v02.n493
Hi Joenetters
I tried the ultrapath setup on several occasions. The last time on my
26/45 transformer coupled amp. Everytime I got an improvement:
transparency, and a kind of air and ambience of the recording hall
(try it on several Carnegie Hall records...). This is the first trick
that improves the performance and costs less than the standard
lay-out. Did the same with my 417 line stage, the 71A line stage,
the 807SE, the 6SJ7/45 and now the 26/45.
Some quick thoughts, since I switched from the 6SJ7/45 to the 26/45.
1. Heat your DHT with constant current (see Manfred Hubers homepage,
thanks for answering silly questions...)
2. Use transformer coupling instead of caps. I modified the Athur
Loesch pre and changed the last stage to a Lundahl 1660 -> wow!
Lundahls interstages are as expensive as most of the audiophile caps,
so no excuses....
I made my first transformer-linestage one month before reciving the
SP-mag (inspired guess?). But Thomas Mayer's setup did the rest.
("There is no audio problem, that can't be cured with an additional
piece of iron...")
Josef
P.S. the Ultrapath circuit is also in the Radiotron Cunningham Manual
12 (I think or 11) dated 1934
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=========================================================================
From: tube@jump.net
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Fri, 24 Mar 2000 09:28:02 -0600
Source: Sound Digest Archive v02.n494
"T. Loesch" wrote:
> Hi there,
>
> >Maybe a dumb question, but how is this ultrapath cap anything more than
> >just another (RC) filter stage on the power supply?
>
> Simple. Draw out the AC equivalent Circuit. With the Cathode Cap unbypassed
> the AC Path returning from the Anode to the Cathode of the valve includes
> this Capacitors and the Output Transformer, as well as the Valve, nothing
> else.
>
> Normally you have the PSU Capacitor (quite possibly a nasty, distorting
> electrolytic) and the Cathode Bypass Cap (another 'lytic?)in the AC Loop.
> "Ultrapath" provides a much cleaner "path" for the AC by using only one Cap
> and a rather high Quality, mosdest Value one.
[Snip]
Yup, the only way I have found to understand what happens here is to
view the parafeed choke as a current source, which it is at all but the
lowest frequencies. If the CS delivers a constant 1 A in, then that 1 A
MUST go out, somewhere. If the transformer/PF cap are tied to the
cathode, then the only two places it can go are thru the cathode
resistor and the grid. If the grid draws negligible current, then the
cathode resistor has a CONSTANT 1 A thru it, yielding a constant
voltage, with no need for a bypass cap. Tie the transformer/cap to
ground, however, and suddenly you need that bypass cap.
Also, the grid current is inherently at a much higher impedance than
the cathode, so it doesn't need a low impedance from cathode to ground.
In other words, for the grid, a normal cathode resistor can easily be
low enough already, with no need for a bypass. The fact that several
people here state that PF sounds better with no bypass cap or only a
high quality one suggests that it does not help the grid current to a
significant degree. Also, there will be fluctuations due to the main
power supply, and from the low frequency limitations of the choke,
both of which will tend to store energy in the bypass cap. If it is a
nasty electrolytic, then it will proceed to release this energy at
obnoxious times, messing up the sound. Since the grid doesn't need a
low impedance path, adding one via a bad cap will simply mess up the
sound.
Note, however, that this is the one case where a resistor (in the
cathode) may sound better than iron, because we do want at least a
medium impedance path for the grid. Of course, a small cap could take
care of this, leaving the cathode choke (in addition to a resistor)
to provide other benefits--whatever those might be!
Finally, let me disagree with the idea that PF adds a cap to the
signal path. In a normal SE design, the current flows thru the trans
to a power supply cap and eventually to ground. Parafeed simply MOVES
this cap to a different location! In both cases the current MUST flow
through a power supply cap. The only difference is that normally, a
cap must supply a low impedance path to ground for the amplifier AND
it must filter 120 Hz. In a parafeed, it simply has to supply the low
impedance path to ground, with no added filter duties.
People can say that parafeed has always been around, but contrary to
what Bob C. said, in RD4 it is shown only with a resistor, not a choke,
in the power supply lead. In practice, this is impossible to use for
power amps, due to the unbelievably high voltages and power dissipation
needed for the resistor. By coincidence, however, it was shown right
next to a figure of a regular amp with a choke load. Maybe the
juxtaposition of these two figures was what gave Mikey the idea? I will
say it again; my disagreements with "the Magnequest gang"
notwithstanding, parafeed is a FANTASTIC idea, and it simply would not
have occurred without Mike LeFevre pursuing it, period.
Phil Yates
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Fri, 24 Mar 2000 10:23:29 GMT
Source: Sound Digest Archive v02.n494
Hi there,
>Maybe a dumb question, but how is this ultrapath cap anything more than
>just another (RC) filter stage on the power supply?
Simple. Draw out the AC equivalent Circuit. With the Cathode Cap unbypassed
the AC Path returning from the Anode to the Cathode of the valve includes
this Capacitors and the Output Transformer, as well as the Valve, nothing
else.
Normally you have the PSU Capacitor (quite possibly a nasty, distorting
electrolytic) and the Cathode Bypass Cap (another 'lytic?)in the AC Loop.
"Ultrapath" provides a much cleaner "path" for the AC by using only one Cap
and a rather high Quality, mosdest Value one.
Another trick is to leave the Cathode bypassed (but with a small Value
Resistor in Series with the Cap) and make the "Ultrapath" Cap to a size of:
C(u) = (1 + Mu) * C(k)
where C(u) is the Ultrapath Cap, C(k) the Cathode Bypass and Mu is the Mu of
the valve. This will significantly increase the PSRR of the Valve &
Transformer Stage as well as providing a high Quality, modest Value Cap to
complete the AC loop (at least above a few 100 hz).
Clearer?
Later Thorsten
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=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Fri, 24 Mar 2000 11:36:04 GMT
Source: Sound Digest Archive v02.n494
Darryl,
>There is still a resistor a power supply electro in parallel with the cap
>in the circuit you describe (and the rest of the power supply further back.
Yes and no.... Remeber, current flows allways the way of the least
resitance. The amount of AC Current flowing the "long way" through the PSU
and the various resiators) is very small compared to the amount flowing
through the "Ultrapath" Cap.... So small in fact that it can be safely
discarded in the context.
We have tried to measure it and there was little to measure at normal Audio
Frequencies.
>Same thing happens if you bypass the electrolytic in the power supply with
>a smaller better cap.
Not quite.
>I think it was you (I may be wrong) who recommended not just wiring the
>bypass cap straight across the electro, but to add a small series
>resistance to fight resonances between the two caps.
I do recommend this indeed. So do others.
>The output of the bypassed/filtered power supply is then the voltage acoss
>the bypass cap and this is where the output transformer connects. When you
>do this, it starts to look a lot like ultrapath, except for the cathode
>bypass cap of
>course, and your recommendations here would still apply.
Yes. However by placing the Ultrapath Cap we (can) eliminate the Cathode
Bypass Cap and we use one high quality Cap for the "whole" signal, rather
than a bypassed combo. It does sound better this way. A lot better.
>I'm not saying ultrapath won't work, I am just suggesting is sounds better
>for much the same reasons as those that account for the better sound of
>bypassed electro's in power supplies.
Yes, However it is a more effective way of "bypassing" as it indeed does
what it says, it makes the AC Signal current "bypass" (eg not flow through)
the PSU Cap (discounting a small redux....).
Again, draw up the equivalent AC Circuits (taking care to include all
relevant parasitics like ESR and ESL on the Cap's).... Then see what the
Impedance ratios left in the circuit are.
Later Thorsten
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=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Fri, 24 Mar 2000 13:46:24 GMT
Source: Sound Digest Archive v02.n494
Hello,
>What do you think, in a convencional output or PF, in the cathode,
>instead the cap+r // R that you proposed, use a LM317 as CS (or another
>CS) in series with a smaller R (or just the CS)?
We intend to try the CCS in a 2A3 PP Amplifier soon. We (London Live) have
been using Valve based (Penthodes) CCS's in the tail of output stages with
excellent success.
In SE Circuits I have not yet tried it. But how about another Choke in the
Cathode instead of a CCS? Why use sand if you can use Iron?
Later Thorsten
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=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Fri, 24 Mar 2000 15:40:08 GMT
Source: Sound Digest Archive v02.n494
Gordon,
>If nothing else we are obsesive, who uses cheap caps.
Well, for starters, Darryl does... ;-)
I don't, of course.
>Second why not just fix bias the tube?
Yup. Or why not direct-couple to the preceeding gainstage, using eith the
Approach Komuro uses, my preferred approach or any other conceivable
option.... That fixes the Bias while we are at it.
There are many possible options. I was just highlighting a few specific
ones.
Later Thorsten
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=========================================================================
From: "Darryl Lock" <dklock@ieee.org>
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Fri, 24 Mar 2000 19:31:32 +1000
Source: Sound Digest Archive v02.n494
>
> Hi Joenetters
>
> I tried the ultrapath setup on several occasions. The last time on my
> 26/45 transformer coupled amp. Everytime I got an improvement:
> transparency, and a kind of air and ambience of the recording hall
> (try it on several Carnegie Hall records...). This is the first trick
> that improves the performance and costs less than the standard
> lay-out. Did the same with my 417 line stage, the 71A line stage,
> the 807SE, the 6SJ7/45 and now the 26/45.
>
Maybe a dumb question, but how is this ultrapath cap anything more than just
another (RC) filter stage on the power supply? Is it just another case of
bypassing the big electro's in the power supply with a better capacitor?
Darryl
=========================================================================
From: "Darryl Lock" <dklock@ieee.org>
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Fri, 24 Mar 2000 20:54:59 +1000
Source: Sound Digest Archive v02.n494
> Hi there,
>
> >Maybe a dumb question, but how is this ultrapath cap anything more than
> >just another (RC) filter stage on the power supply?
>
> Simple. Draw out the AC equivalent Circuit. With the Cathode Cap
> unbypassed
> the AC Path returning from the Anode to the Cathode of the valve includes
> this Capacitors and the Output Transformer, as well as the Valve, nothing
> else.
There is still a resistor a power supply electro in parallel with the cap in
the circuit you describe (and the rest of the power supply further back.
Same thing happens if you bypass the electrolytic in the power supply with a
smaller better cap. I think it was you (I may be wrong) who recommended not
just wiring the bypass cap straight across the electro, but to add a small
series resistance to fight resonances between the two caps. The output of
the bypassed/filtered power supply is then the voltage acoss the bypass cap
and this is where the output transformer connects. When you do this, it
starts to look a lot like ultrapath, except for the cathode bypass cap of
course, and your recommendations here would still apply.
I'm not saying ultrapath won't work, I am just suggesting is sounds better
for much the same reasons as those that account for the better sound of
bypassed electro's in power supplies.
Darryl
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Fri, 24 Mar 00 09:36:07 -0500
Source: Sound Digest Archive v02.n494
>Simple. Draw out the AC equivalent Circuit. With the Cathode Cap unbypassed
>the AC Path returning from the Anode to the Cathode of the valve includes
>this Capacitors and the Output Transformer, as well as the Valve, nothing
>else.
>
>Normally you have the PSU Capacitor (quite possibly a nasty, distorting
>electrolytic) and the Cathode Bypass Cap (another 'lytic?)in the AC Loop.
>"Ultrapath" provides a much cleaner "path" for the AC by using only one Cap
>and a rather high Quality, mosdest Value one.
>
>Another trick is to leave the Cathode bypassed (but with a small Value
>Resistor in Series with the Cap) and make the "Ultrapath" Cap to a size of:
Thorsten,
If nothing else we are obsesive, who uses cheap caps.
Second why not just fix bias the tube?
Gordon
=====> Wavelength Audio <=====
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "P. de R. L." <triode@bow-tie.org.uk>
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Sat, 25 Mar 2000 01:16:50 -0000
Source: Sound Digest Archive v02.n495
We've a great company in England; Mainline Surplus (includes Chester the
Cat)
I just bought a bag of capacitors for £5 (=$8US). Brilliant! For a start
there were 3 good-qulaity 220uf 450V caps plus loads of 200V Nichicons of
all sorts of values. I found Oscons in there too. there must be about
500capacitors all told - maybe more All the ones I've tried re=formed
really quickly..
Paul
- ----- Original Message -----
From: Darryl Lock <dklock@ieee.org>
To: <sound@lists.io.com>
Sent: Saturday, March 25, 2000 12:14 AM
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
>
> >
> > Gordon,
> >
> > >If nothing else we are obsesive, who uses cheap caps.
> >
> > Well, for starters, Darryl does... ;-)
>
>
> Listen, this is not TNT-list so behave yourself!!! :-)
>
> I have been known to install film and foil orange drops, and use Nichicon
> caps in power supplies. Maybe not always to your exotic tastes, but not
> cheap either.
>
>
> Darryl
>
>
=========================================================================
From: "Darryl Lock" <dklock@ieee.org>
Subject: RE: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Sat, 25 Mar 2000 10:14:58 +1000
Source: Sound Digest Archive v02.n495
>
> Gordon,
>
> >If nothing else we are obsesive, who uses cheap caps.
>
> Well, for starters, Darryl does... ;-)
Listen, this is not TNT-list so behave yourself!!! :-)
I have been known to install film and foil orange drops, and use Nichicon
caps in power supplies. Maybe not always to your exotic tastes, but not
cheap either.
Darryl
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Mon, 27 Mar 2000 14:16:16 GMT
Source: Sound Digest Archive v02.n498
Hi there,
>That's very interesting because when I tried to connect my 46 driver (350v)
>B+ cap (100uF) to the cathode (at 130v) of my Loftin-White Shishido style
>driver circuit (26 DC to 46 driving 300B via IT on fixed bias)I got a slow
>oscillation.
You would. What you did was to remove the PSU decoupling (the PSU nos sees
the PSU Decoup Cap in series with the Cathode Resistor. The result - you
start the motorboat....
>This stopped when I connected it to ground and added a 220uF
>TSHA cahode R bypass cap. I am using a CC filament supply for the 46.
>
>Later I swapped the 100uF TSHA for a 8uF Dubilier (Wagga Wagga style)
>and found a really nice improvement in 'liquidity'.
Try the 100uF back, no Cathode Bypass and the 8uF from the (now decoupled)
+B to the 46 Cathode. This should sound even better and should not
motorboat....
>what advantage is there in not using an autotransformer for PF ?
Only the full blocking of quite high DC potentials. Otherwise I'd think a
really nice Autotransformer might very well be "the Job"....
In the whole ongoing discussion I have also thought that the "offhand" Idea
of doing Parafeed with the Retard-coil in the Cathode might be a better idea
than I thought.
So, +B would go to the Anode, the PF Transformer from +B via a blocking Cap
to the Cathode. The Inductor goes into the Cathode Circuit, in series with
the Bias Resistor.... I don't think it will allow the Inductor to be reduced
in Value though....
But again, no Autotransformer.
Later Thorsten
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=========================================================================
From: Martin Seddon <mseddon@iinet.net.au>
Subject: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Mon, 27 Mar 2000 21:47:25 +0000
Source: Sound Digest Archive v02.n498
===================
Date: Thu, 23 Mar 2000 13:44:01 -0800
From: David Home <DHome@creo.com>
I use CCS heating as well and love it. However the filament needs to be AC
reference tied to ground through a cap or AC/DC coupled by using a fixed
bias on the grid.
Sorry if I was not clear. Regards, David
==================================
That's very interesting because when I tried to connect my 46 driver (350v)
B+ cap (100uF) to the cathode (at 130v) of my Loftin-White Shishido style
driver circuit (26 DC to 46 driving 300B via IT on fixed bias)I got a slow
oscillation. This stopped when I connected it to ground and added a 220uF
TSHA cahode R bypass cap. I am using a CC filament supply for the 46.
Later I swapped the 100uF TSHA for a 8uF Dubilier (Wagga Wagga style)and
found a really nice improvement in 'liquidity'. My 1935 reference book has
all the B+ bypass caps returned to the cathodes including parallel feed. PF
does then seem to be just a variation of a family of circuits.
Maybe a small cap to ground would stabilise the above and allow the B+ cap
to return to the cathode? And eliminate the cathode bypass cap.
The auto transformer thing Dave Slagle brought up sticks in my mind - what
advantage is there in not using an autotransformer for PF ? Is it not much
more efficient in terms of turns / inductance / parasitics?
Never mind the tapped choke on the B+ and chucking out the PF trannie
altogether. Funny there is no mention of this in the old testement - or is
there?
Sorry if I'm a bit behind on all this - digests piling up.
Rgds,
Martin
=========================================================================
From: Paul Joppa <pdjoppa@home.com>
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Wed, 29 Mar 2000 21:32:04 -0800
Source: Sound Digest Archive v02.n505
"T. Loesch" <ezee_e@hotmail.com> said ....
In the whole ongoing discussion I have also thought that the "offhand"
Idea
of doing Parafeed with the Retard-coil in the Cathode might be a
better idea
than I thought.
So, +B would go to the Anode, the PF Transformer from +B via a
blocking Cap
to the Cathode. The Inductor goes into the Cathode Circuit, in series
with
the Bias Resistor.... I don't think it will allow the Inductor to be
reduced
in Value
==============================
Paul Joppa says ...
Thorsten? Is that really you? I thought you didn't like cathode
followers? :^)
This is Circuit I from my little note in VALVE v6n5 "Twelve Ways to
Parafeed". It's one of two common-cathode and two cathode followers in
which the output signal current path is confined to the tube, cap, and
transformer. It would require an extremely clean power supply though,
because the input is referenced to ground but the output is referenced
to B+. Thus it misses one of the big parafeed advantages, power supply
isolation.
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - Ultrapath?
Date: Thu, 30 Mar 2000 10:45:58 GMT
Source: Sound Digest Archive v02.n505
Paul,
>Thorsten? Is that really you? I thought you didn't like cathode
>followers? :^)
I don't, and that Circuit ain't one. Or rather it ain't one for AC, it is
for DC though....
>which the output signal current path is confined to the tube, cap, and
>transformer. It would require an extremely clean power supply though,
>because the input is referenced to ground but the output is referenced to
>B+.
Sure.
>Thus it misses one of the big parafeed advantages, power supply
>isolation.
We been around this....
Later Thorsten
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=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: [JN] Paraffed - a bl%&$y Engineers view - was: Parallel feed helps power output?
Date: Thu, 23 Mar 2000 11:56:32 GMT
Source: Sound Digest Archive v02.n492
Hi folks,
In this whole discussion a few things cropped up that I feel need some
enlarging on. Specifically, there seem to be a few things happening in the
AC Domain that are not being well noticed.
So here goes.....
Let's start at the End and work our way forward. The Parafeed OPT operates
without Airgap, DC Bias (pre-magged core) and such. As a result it is fully
subject to the low level distortion induced by the Hysteresis of the Core
Material (not that it matters with CD Sources, it might with LP and
conventional steel cored PP OPT's). Furthermore, it's primary inductance is
fully subject to the modulation by signal level.
All this suggests that a classic PP OPT is not ideally suited. We need a
very high Quality core material to get a high enough Inductance to push any
modulation effects into insignificance, also better core material
(Permalloy, Mu-Metal, Permadur, Nickel) allows a physically smaller OPT,
making the HF behaviour better.
Now, essentially this OPT is hooked up between the Anode of the Output Valve
and it's Cathode with a Capacitor to Block DC. If the Output Valve is being
operated in Self Bias Mode I feel that the Parafeed OPT should be returned
to the Cathode, not ground. This eliminated the Cathode Bypass Cap from the
AC Loop.
Indeed, at least in simulations and various Preamp's no Cathode Bypass Cap
was found to be neccesary at all, this is something I intend to try with a
Friends Paraglow, as soon he finishes f%&@#g wiring up the thing....
Now, the Anode of the Valve needs to be fed with DC. This is our normal
Anode Supply, but if we used this directly, we would shunt the Anode to
ground, AC wise. So we need to introduce something with a high AC Impedance
but low DC Resistance. Here a Retard Coil or Choke answers this purpose most
admirably, as long as the inductance is high enough.
With that, we have the classic Parafeed Output Stage.
Now some thoughts on sonics. First of all, in parafeed Amplifiers we apply a
large degree of isolation between PSU and Amplifier Circuit for AC. This
means if only cheap chemical Cap's are used, they will be effectively be
removed from the Signalpath. This is not to say that the PSU Design and
Parts Quality will not have audible consequences, but they will be much
diminished.
I believe this to be the KEY Mechanism in the subjectively percieved
Improvement with Parafeed Circuits. The whole PSU is AC wise isolated from
the Circuit and whatever PSU Cap was used is now in AC terms replaced by the
Parafeed Coupling Cap.
So the Parafeed coupling is really not an addition to the signal-path, it
replaces the final PSU Filter Cap. As there most experimenters will usually
use a much higher quality Cap than in the PSU, the improvements should be
quite dramatic.
If the (possibly also cheap electrolytic) Cathode Bypass Capacitor is
avoided by returning to the Cathode the improvement should be even bigger.
Indeed, a Loftin White Amplifer using no Bypass Cap on the Cathode of the
Driver and a Parafeed Output could be build which has only ONE Capacitor
(the parafeed coupling Cap) in AC or "signal" circuit.
Lastly, as mentioned, any Transformer I know specifically designed for
Parafeed Applications (Magnequest, Sowter) is usually offered with a Core
containing at least a ceratain percentage of high quality core materials,
they are physically smaller and so on. This will quite clearly conspire to
offer higher sound quality as a conventional Steelcored SE OPT, assuming
competent construction of both transformers of course.
That said, Anode load choke and Parafeed OPT together cost usually a good
deal of money, often enough for a quite high quality conventional SE OPT. So
one will have to weight up the advantages and disadvantages.
Now, from what I have said above there should be a clear path for improving
"conventional" Amplifers. I would suggest to return a suitable value and
Quality Capacitor from the +B End of the OPT to the Cathode of the Valve.
In order to "promote" AC current flow through this high Quality Cap, rather
than through the nasty electrolytics I would suggest a 10 ohm (non inductive
- - Allen Bradly CC or Caddock or similar) in Series with both the +B Lead
between OPT and the final Filter Cap and in series with the Cathode Bypass
Cap.
A suitable Value PSU Choke in the +B Lead would also be a very attractive
proposition.
Of course, another option is to use really quality capacitors throughout the
whole Amplifier to start with. In this case and with a high quality SE OPT I
suspect that differences between PF and classic SE will be considerably
smaller.
I hope this helps and gave a bit food for thought.
Later Thorsten
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=========================================================================
From: "P. de R. L." <triode@bow-tie.org.uk>
Subject: Re: [JN] Paraffed - a bl%&$y Engineers view - was: Parallel feed helps power output?
Date: Thu, 23 Mar 2000 18:58:17 -0000
Source: Sound Digest Archive v02.n493
> All this suggests that a classic PP OPT is not ideally suited. We need a
> very high Quality core material to get a high enough Inductance to push
any
> modulation effects into insignificance, also better core material
> (Permalloy, Mu-Metal, Permadur, Nickel) allows a physically smaller OPT,
> making the HF behaviour better.
>
Perhaps a toroid with its ultra-low leakage?
paul
=========================================================================
From: Tim Reese <tgrmail@nmr.MGH.harvard.EDU>
Subject: parafilm (was [JN] Re: Tonearm dampening)
Date: Mon, 17 May 1999 16:33:19 -0400 (EDT)
Source: Sound Digest Archive v02.n145
If any joes want to try this, send me a SSAE and I'll send you an envelope
sized piece.
T. Reese
42 Eighth St. #5107
Charlestown MA 02129
cheers tr
- ----------------------------------------------------------------------
Tim Reese, MGH NMR Center reese@nmr.MGH.harvard.edu
>An excellent dampening material in my experience has been Parafilm. Its used
>in the medical field to seal petrie dishes and test tubes, etc. and works
>similar to Saran wrap:cut a piece and wrap it around something and it sticks
>to itself. Its also made of some kind of stabilized paraffin so it is easy
>to remove (and easy to melt, so don't try it around your DHT's). I see it
>now advertised in model catalogs as a paint mask, but any medical supplier
>has it, ask your doctor and he'll probably have some and give it to you.
>A flute player in the Philadelphia Orchestra turned me on to this.
>Apparently, he uses it to seal the joints on his instrument and it improves
>the tone. I use a very small amount in 1/8 to 1/16th" strips and place it
>close to the junctions of every piece i.e. the ends of the arm tube, the
>base of the headshell lift, the end of the cueing lever, etc. The effect is
>quite amazing as the paraffin is a very good dampener. Detail increases and
>the noise floor drops.
>
>Stu
=========================================================================
From: "PEARL Cust Serv" <custserv@pearl-hifi.com>
Subject: [JN] Paralled PP OPTs - was: Monkey Amps
Date: Mon, 07 Aug 2000 11:50:04 -0600
Source: Sound Digest Archive v02.n619
Hi Ken:
>>> Unfortunate that I am lumped in with you nasty, brutish lot--after
>>> all, I'm a bit of the odd man with my 600W of push-pull thermionic
>>> psychomadness. it's not like Ii had a choice: God only speaks to me
>>> when my chest caves in.
I wouldn't let any carelessly cast aspersions stick any longer than it
takes for them to bounce off and onto the ground where, hopefully, they'll
make halfway decent organic fertilizer
>>> (I actually LIKE it around here!)
Me too . . .this is a great list . . .
>>May I be so crass as to inquire what you use for iron?
>>
>>Doug Purl
>
> The bang-for-the-buck approach... two hammond 1650w's, each driven by 6
> KT90's @ 620VDC into AB2. triode/UL switchable.
>
> Nobody seems to make really huge audio OPT's anymore, at least off the
> shelf. the double OPT thing does have it's advantages, though.
>
> Ken
If you connect these exactly in parallel they will work fine, but if you
hook them in opposing parallel they'll work better.
By that I mean that instead connecting of one set of 0, 4, 8 & 16 Ohm
sec taps to their correspondents, connect the one trannie's '0' to the
other's '16', the '4' to the '4' and the '16' to the '0'.
Don't connect the '8s' together and don't try to use them.
The benefit here is that the AC and DC unbalances in the two coils are
pretty much balanced . . . Try it, you might be surprised . .
Bill - PEARL, Inc.
=========================================================================
From: Ken Gilbert <ride5000@ride.ri.net>
Subject: Re: [JN] Paralled PP OPTs - was: Monkey Amps
Date: Mon, 07 Aug 2000 16:13:14 -0400
Source: Sound Digest Archive v02.n620
> If you connect these exactly in parallel they will work fine, but if you
>hook them in opposing parallel they'll work better.
> By that I mean that instead connecting of one set of 0, 4, 8 & 16 Ohm
>sec taps to their correspondents, connect the one trannie's '0' to the
>other's '16', the '4' to the '4' and the '16' to the '0'.
> Don't connect the '8s' together and don't try to use them.
> The benefit here is that the AC and DC unbalances in the two coils are
>pretty much balanced . . . Try it, you might be surprised . .
that's good thinking, bill (one of the reasons i love the joelist). i'm
planning a big ass bass amp, so i may end up doing that very thing.
actually, the way i've currently got it set up, there is a svet 6n1p set up
as a differential driver, common to both "channels," with a tail resistor
tied to -300V and plate R's to +300V. this drives 4 coupling caps, and 4
bias injection/adjustment schemes (about -80V or so), which are then fed to
the grids of 4 el84's. the el84's are currently run in triode mode (have
plans and parts to go full pentode mode as soon as i can find the time) as
cathode followers, from +/-150VDC supplies. the el84's have 1st
approximation constant current sinks off their cathodes (BUX85 BJT, zener
reference) set to 15mA. finally the kt90's are bringing up the rear, with
4 current sense R's in each cathode circuit. g1 and g2 stoppers on the
kt90's are 4k4 and 2k2 respectively to keep things reasonably balanced.
idle current is set to an average of 30mA per tube for a dissipation of
about 18W.
so the signal is split from the CF drivers on back to the output terminals,
whereupon i send the prodigious current downstream to two different 4x12"
speaker cabinets. the cabs are 2R nominal (all 4 speaks in parallel) and
are run off the 4R tap of the hammonds. (it sounds a little crunchier that
way.)
with such a scheme, as the power stages are driven into distortion (believe
it or not, they are!) they are free to exhibit their own unique character
to the tone, along with the differing responses of the cabinets themselves.
when mics are placed on each of the two cabinets and panned hard R and L,
a very wide yet coherent soundstage is presented. it is tighter than
double tracked guitars (and easier too) but retains much of the thickness
and richness of a multi-tracked setup, as well as a hint of a "hole" in the
CL of the image.
the current setup also allows me to pull a front-mounted 1A sloblow fuse
(which feeds the OPT CT's) and go back to one cabinet/one channel
operation. it comes in handy when i'm playing by myself.
those kt90's are just so great in triode OR ul--it doesn't matter which.
it's just such a crying shame about those tubes.
oh yeah.. there ain't a speck of loop NFB in the amp. that's another
trick... nothing to fall apart and break down as the signals get crazy.
kg
=========================================================================
From: Paul Joppa <pj@bottlehead.com>
Subject: Re: [JN] Parallel connection of vacuum tube rectifiers?
Date: Mon, 09 Apr 2001 21:15:13 -0700
Source: Sound Digest Archive v02.n862
I recall seeing somewhere the idea that with diodes in parallel,
the lower impedance diode will draw more current and lose
emission more rapidly, causing the current to equalize as the
tube wears out. If both sections are in the same envelope, the
total heat dissipated by both plates is relatively independent
of the division of current, so they would probably accept higher
dissipation of one section as long as the other was lower.
Triodes are much less forgiving; a relatively small difference
in mu will cause one of a parallel pair to take much more
current, and reduced emission capacity won't help as much. So
triodes (in series regulator circuits for instance) often have
specifications that require equalizing resistors.
- -Paul Joppa
=========================================================================
From: "Hans Hedal" <hans.hedal@post.cybercity.dk>
Subject: Re: Re: [JN] Parallel connection of vacuum tube rectifiers?
Date: Wed, 11 Apr 2001 10:58:22 +0200
Source: Sound Digest Archive v02.n864
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Thank you all for answering my question.
You have helped me continuing my work on my homebrew amplifier.
Happy Easter
Hans
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=========================================================================
From: "Stewart Ono" <audiodir@gte.net>
Subject: [JN] Re: paralleled Diodes
Date: Sat, 29 May 1999 14:01:34 -1000
Source: Sound Digest Archive v02.n158
Here's a tidbit that may ignite even more flames: I parallel diodes,
including hexfreds, with rectifier tubes. I get the high current, high
voltage (no slow turn on, unfortunately) of the diodes plus I get the tube
rectifier sound, better dynamics and a better midrange presence. Another
plus is that I can run any rectifier tube I like as its switching speed is
more critical than the current it flows. Of course, you have to change your
capacitors to withstand the new voltage limits, and dropping resisters to
compensate but it is a way to get the best of both worlds. I can't measure
the switching speed ,but on my 'scope noise floor is lower than by running
any of the two alone (at least in the first filtering stage of a standard Pi
network).
As for circuit board work, I can not more highly recommend the use of lead
free solder. I use multicore SN96:96 %tin, 4 %silver, and Digikey now lists
it in their catalog. I had to special order a case of 20# a year ago but
thankfully I've used or sold most of that case. For those skeptics, Sony
professional (not consumer) video, will not warranty any repairs not done
with this solder as video quality is impaired. I use it exclusively now,
both for performance and health reasons, and small amounts can be found in
most Radio Shack outlets although they have both silver and copper alloy
solders. With hard wired units,built to military soldering standards (one
full tight turn of the component leads on the connecting lug) the
differences are rather minute as you have pretty good metal to metal
contact. On a circuit board where the component lead simply floats in the
holes and solder often the only connection, the differences can be
profound,especially in preamp and other low level stages. On my WTCP iron I
had to change to 700 degree tips as the solder is not eutectic and melts at
590.
Stu
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] Re: paralleled Diodes
Date: Sun, 30 May 1999 13:46:39 +0200
Source: Sound Digest Archive v02.n158
Since the Hexfred has a lower dynamic impedance and lower dc drop I doubt
if any current runs through the tube.
In order to verify that, a measurement shall be caried out.
As a side effect the tube might add some damping but this may be achieved
by a series network of say 100 ohm and some capacitance.
Switching speed of diodes in this application is of little importance since
you have 10 ms at hand.
I look forward to your response
Have fun
Guido
>At 14:01 29/05/99 -1000, Stewart Ono wrote:
>Here's a tidbit that may ignite even more flames: I parallel diodes,
>including hexfreds, with rectifier tubes. I get the high current, high
>voltage (no slow turn on, unfortunately) of the diodes plus I get the tube
>rectifier sound, better dynamics and a better midrange presence. Another
>plus is that I can run any rectifier tube I like as its switching speed is
>more critical than the current it flows. Of course, you have to change your
>capacitors to withstand the new voltage limits, and dropping resisters to
>compensate but it is a way to get the best of both worlds. I can't measure
>the switching speed ,but on my 'scope noise floor is lower than by running
>any of the two alone (at least in the first filtering stage of a standard Pi
>network).
>As for circuit board work, I can not more highly recommend the use of lead
>free solder. I use multicore SN96:96 %tin, 4 %silver, and Digikey now lists
>it in their catalog. I had to special order a case of 20# a year ago but
>thankfully I've used or sold most of that case. For those skeptics, Sony
>professional (not consumer) video, will not warranty any repairs not done
>with this solder as video quality is impaired. I use it exclusively now,
>both for performance and health reasons, and small amounts can be found in
>most Radio Shack outlets although they have both silver and copper alloy
>solders. With hard wired units,built to military soldering standards (one
>full tight turn of the component leads on the connecting lug) the
>differences are rather minute as you have pretty good metal to metal
>contact. On a circuit board where the component lead simply floats in the
>holes and solder often the only connection, the differences can be
>profound,especially in preamp and other low level stages. On my WTCP iron I
>had to change to 700 degree tips as the solder is not eutectic and melts at
>590.
>Stu
>
>
>
>
=========================================================================
From: "spence barton" <ence-ack@rio.com>
Subject: Re: [JN] Re: paralleled Diodes
Date: Tue, 1 Jun 1999 10:25:56 -0700
Source: Sound Digest Archive v02.n161
>Right, and you could even run no rectifier tube at all and not have any
>change: your tube rectifiers are not even conducting, as the 'freds turn on
>far earlier (at a lower voltage drop),and thus hog all the current. The
>only way to get the tube rectifiers to be active would be to outfit the
>diodes and tubes with series resistors to provide load sharing. If your
>tube rectifiers are gas diodes (MV rectifiers, etc), the resistors in
>series with the hexfreds will have to be quite large to match the voltage
>drops.
Yes, on paper the tube rectifiers, when in parallel with solid state diodes,
don't conduct but ANYONE can hear the difference when you remove the tube
from this arrangement. I was introduced to this in a very small hi-fi shop
in Honolulu by a man named Stuart in about 1991. Since then I have built a
few parallel silicon/vacuum tube rectifiers and it has always been quite
audible to me and others when the tubes are removed. Solid state rectifiers
when paralleled by vacuum tubes loose that "4007" sound.
The first time I built one was with damper diodes. You could fire up the amp
with the damper diodes pulled and listen for an hour and then in the middle
of a piece of music you could plug in the tube rectifiers and hear them
improve the sound as the filaments warmed up.
So anyway, be careful brother Frank about saying things like the first
sentence of your post above, if you haven't listened to the circuit in
question. There IS DEFINITLY a change when the rectifier tube is pulled. I
wouldn't want to speculate on the mechanism, except to say that perhaps the
tube calmly conducts during the tiny portion of each cycle when the SS
diodes are turning themselves inside out switching.
Theory is wonderful until it is contradicted by empirical results.
spence
=========================================================================
From: "spence barton" <ence-ack@rio.com>
Subject: Re: [JN] Re: paralleled Diodes
Date: Tue, 1 Jun 1999 12:46:42 -0700
Source: Sound Digest Archive v02.n161
- -----Original Message-----
From: Scott Grammer <tubedude@cdc.net>
To: spence barton <ence-ack@rio.com>; Joenet <sound@lists.io.com>
Date: Tuesday, June 01, 1999 10:37 AM
Subject: Re: [JN] Re: paralleled Diodes
>
>
>spence barton wrote:
>
>> (snip)Yes, on paper the tube rectifiers, when in parallel with solid
state
>> diodes,
>> don't conduct but ANYONE can hear the difference when you remove the tube
>> from this arrangement.(snip)
>
>While not trying to force Edisonism down anybody's throat, is it possible
that
>the difference in sound is caused by the fact that the 10 or 15 watt load
>imposed on the power transformer by the rectifier filament is being removed
>along with the tube?
Filaments for diodes not on main B+ transformer. If loading a power trans by
an extra 15 watts will do as much for the sound of an amp I'll put an extra
100Watt load on it. It sounds like more voodoo for an amp to be positively
effected by an increased load on the power trans than for the tube to make
the difference.
If it is too hard for you to accept that having a tube diode in parallel
with a SS diode makes a difference in the sound, I will admit that hear a
light difference in the quality of hum coming from the transformer on the
power pole two houses down when I hooked up the extra filament trans. Yeah,
that probably is what made the difference.
Unless you think damper diodes and 4007's sound the same I can safely say
you'll hear the tube. I now leave the SS diode out because I don't think it
adds anything... the tube rectifier dominates the sound.
=========================================================================
From: "Frank Deutschmann" <Frank_Deutschmann@trepp.com>
Subject: Re: [JN] Re: paralleled Diodes
Date: Tue, 1 Jun 1999 12:47:34 -0400
Source: Sound Digest Archive v02.n161
"Stewart Ono" <audiodir@gte.net> on 05/29/99 08:01:34 PM
To: sound@lists.io.com
cc: (bcc: Frank Deutschmann/Trepp)
Subject: [JN] Re: paralleled Diodes
Here's a tidbit that may ignite even more flames: I parallel diodes,
including hexfreds, with rectifier tubes. I get the high current, high
voltage (no slow turn on, unfortunately) of the diodes plus I get the
tube
rectifier sound, better dynamics and a better midrange presence. Another
plus is that I can run any rectifier tube I like as its switching speed
is
more critical than the current it flows.
Right, and you could even run no rectifier tube at all and not have any
change: your tube rectifiers are not even conducting, as the 'freds turn on
far earlier (at a lower voltage drop),and thus hog all the current. The
only way to get the tube rectifiers to be active would be to outfit the
diodes and tubes with series resistors to provide load sharing. If your
tube rectifiers are gas diodes (MV rectifiers, etc), the resistors in
series with the hexfreds will have to be quite large to match the voltage
drops.
As for circuit board work, I can not more highly recommend the use of
lead
free solder. I use multicore SN96:96 %tin, 4 %silver, and Digikey now
lists
it in their catalog. I had to special order a case of 20# a year ago but
thankfully I've used or sold most of that case. For those skeptics, Sony
professional (not consumer) video, will not warranty any repairs not
done
with this solder as video quality is impaired.
Video quality is the least of your worries; there are a host of reasons why
this is the wrong solder to use on any modern electronics. Tube gear is
one thing; its probably fine there. But do yourself a favor and don't
attempt to use this stuff on modern components/pc boards.
- -frank
=========================================================================
From: "Chris Beck" <cbeck@brewercompany.com>
Subject: Re: [JN] Re: paralleled Diodes
Date: Tue, 1 Jun 1999 13:37:30 -0500
Source: Sound Digest Archive v02.n161
Could the tube diode be acting like a snubber network of a resistor/cap
combo?
Chris Beck
See my web page at: http://www.execpc.com/~n9zes/index.htm
- ----------
> From: spence barton <ence-ack@rio.com>
>
<SNIP>
> Solid state rectifiers
> when paralleled by vacuum tubes loose that "4007" sound.
>
>
>
>
=========================================================================
From: Scott Grammer <tubedude@cdc.net>
Subject: Re: [JN] Re: paralleled Diodes
Date: Tue, 01 Jun 1999 13:43:57 -0400
Source: Sound Digest Archive v02.n161
spence barton wrote:
> (snip)Yes, on paper the tube rectifiers, when in parallel with solid state
> diodes,
> don't conduct but ANYONE can hear the difference when you remove the tube
> from this arrangement.(snip)
While not trying to force Edisonism down anybody's throat, is it possible that
the difference in sound is caused by the fact that the 10 or 15 watt load
imposed on the power transformer by the rectifier filament is being removed
along with the tube?
S.G.
- --
TubeDude's Webpage of Vacuum Tube Lore! http://www.cdc.net/~tubedude/
Smoke Free Youth! http://www.cdc.net/~tubedude/smokefreeyouth.html
The Price of Privacy. http://www.cdc.net/~tubedude/privacy.html
"The nice thing about standards is that you have so many to choose from."
-- Andrew S. Tanenbaum, _Computer Networks_, 2nd ed, p.254
=========================================================================
From: "Bart Shepherd" <bart.shepherd@ttmsolutions.com>
Subject: Re: [JN] Re: paralleled Diodes
Date: Wed, 2 Jun 1999 23:38:53 +1000
Source: Sound Digest Archive v02.n163
> spence barton wrote:
>
> > (snip)Yes, on paper the tube rectifiers, when in parallel with solid
state
> > diodes,
> > don't conduct but ANYONE can hear the difference when you remove the
tube
> > from this arrangement.(snip)
I'm with the guy who asked if perhaps the tube may be acting somewhat
similar to a snubber network.
Try a series cap and r across each diode or even just a cap (say 0.1uf or
bigger).
My money says it will give a similar effect to the tube.
My theory is that the tube somehow damps or filters the switching transients
of the diodes. This would make everyone correct.
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] Re: paralleled Diodes
Date: Wed, 02 Jun 1999 22:03:11 +0200
Source: Sound Digest Archive v02.n164
>While not trying to force Edisonism down anybody's throat, is it possible
that
>the difference in sound is caused by the fact that the 10 or 15 watt load
>imposed on the power transformer by the rectifier filament is being removed
>along with the tube?
Yes, or:
The additional damping across the solid state rectifiers
Must be able to measure that
regards,
- -
Guido
>S.G.
>
>
>--
>TubeDude's Webpage of Vacuum Tube Lore! http://www.cdc.net/~tubedude/
>Smoke Free Youth! http://www.cdc.net/~tubedude/smokefreeyouth.html
>The Price of Privacy. http://www.cdc.net/~tubedude/privacy.html
>
>"The nice thing about standards is that you have so many to choose from."
> -- Andrew S. Tanenbaum, _Computer Networks_, 2nd ed, p.254
>
>
>
>
=========================================================================
From: "Stewart Ono" <audiodir@gte.net>
Subject: [JN] Re: paralleled rectifiers, volume controls, cables
Date: Tue, 1 Jun 1999 15:14:43 -1000
Source: Sound Digest Archive v02.n162
I don't know why a tube paralleled with s/s sounds better. Tried it and
liked it (in the days before the FR diodes became popular and cheap). It
could very well be the tube is acting as a snubber, but I suspect that the
tube is just catching the leading edge of that changing AC waveform, before
the s/s kicks in. A similar effect can be heard with big s/s bridges, say
for a s/s power amp. Before the big amperage fast recovery diodes came out,
I used to parallel smaller FR diodes with say a 15 amp bridge and the speed
of the FR's would be evident. I did have some problem with the small diodes
burning out, but three or four of them in parallel would cure that. Of
course now there are big FR diodes, so this is not necessary.
In regards to Nicholas' comments about using larger resistors, I would
agree. The temperature coefficient usually is more stable, but also I
suspect with modern film components, inductance is lower with the larger
bodies. I've taken apart a few resistors and they usually consist of a
ceramic or glass core with a spiral laser etched pathway through the
deposited conductive material (like a wire wound). A larger diameter lowers
the inductance, not a lot, but sometimes beneficial.
As for volume controls, I believe that a shunt volume is probably the most
cost effective way of dealing with the issue. Use two good resistors in
series ($20 per channel, if you like vishays) and from the center use a
regular volume pot with the wiper tied to ground to bleed the circuit to
ground. The quality of the pot, while still important, is not quite as
critical, as the signal does not really go through the pot. The Reference
Line passive preamps have been doing this for a long time and it seems to be
a very elegant alternative to building complex switching pots.
Cable break in is a complex issue since there are many parameters and
problems which are different but related. One speaker designer says that he
attributes speaker break-in to the fact that wire becomes work hardened in
forming and becomes annealed with playing. He points out that speakers
played very softly do not seem to break in and that louder volumes are
necessary. He believes that it is the heat generated that is annealing the
copper in the inductors and the voice coils....
In some of the work I do, I notice that simply reheating the solder joints
seem to change the sound to the un-broken in state. I also notice that in
doing an A-B-A test sequence, the second switch is the most noticeable. It
seems just moving the contacts in and out has an effect and the components
have to settle out after a switch (about 5 minutes). Cardas uses rhodium
plated rca's for his cables but the ends can be had in silver or gold
plating over the same brass base. The claim is that the precious metals will
gall upon insertion or removal since they are so soft, and this can lead to
less surface contact area. He claims rhodium is harder and smoother, hence
with repeated removal, the surface to surface interface is actually greater.
In some comparisons between the various ends, the precious metal ones do
seem to take longer to break in. Perhaps the precious metal 'flows' a bit
after the initial contact is made by the spring tension of the
ends....Surprisingly, one of the best sounding ends I have tried was the old
mogami, a cheap direct gold plated end with phenolic rather than teflon
insulators. XLO ends are copies of that old design, but with thicker gold
plating doesn't sound anywhere as dynamic as the older stuff. I believe the
old Music Metre and Randall cables used this end.
Others claim that it is residual magnetism induced by current flow. The
XLO/Purist Audio/ Cardas sweep record devices work on this principle. Jim
Aud of Purist says that his disc was developed in conjunction with some NASA
engineers specifically after the failure of a few space probes. They had to
develop an accelerated break in program to not only test the gear but to
insure that after lying dormant for years, could be turned on and be working
at it's peak. I believe it was a Scandinavian company that built a device
called the 'exorcist' . It simply produced a 1kHz toneburst with a
controlled decay and that was supposed to demagnetize the circuit, easy to
replicate with a signal generator (it was a 45 sec decay, if I recall
correctly). The XLO disc doesn't work, at least not in my systems,but the
others do, or, at least, I hear something. They don't work for speaker break
in, however.
Stu
=========================================================================
From: James Melhuish <james@melhuish.org>
Subject: [JN] Parallel feed helps power output?
Date: Wed, 22 Mar 2000 17:02:13 -0500
Source: Sound Digest Archive v02.n491
Hi all,
Sorry if this question has been done over before. I have read several
references (sorry forgot where) that said parallel feed topologies seem
to give more power than standard single ended output transformers. I
believe the quality of the bass was most noticeable, a parallel feed 45
apparently had more bass oomph than a standard single ended 2A3.
What is the consensus here? Would parallel feed buy you more power when
dealing with little output tubes like the 1626?
Has anyone particular likes or dislikes with parallel feed outputs, and
which output tubes seem to like parallel feed and which don't?
James
- --
James Melhuish
mailto:james@melhuish.org
http://melhuish.org
=========================================================================
From: David Home <DHome@creo.com>
Subject: RE: [JN] Parallel feed helps power output?
Date: Wed, 22 Mar 2000 17:37:58 -0800
Source: Sound Digest Archive v02.n491
Hi James. I too have strong opinions on parellel feed and am very much in
the 'pro' camp. I have tried several types of iron with both 2A3 and 300B
and liked it enough to spring for Magnequest 300B parallel feed iron. As the
price is basically double that of good SE iron, I was convinced. Sonically,
I think there is top to bottom an increase in clarity without any edge being
introduced. Now when I listen to conventional SE systems, I hear either a
slight edge with 2A3s or a slight 'fog' with 300Bs. I tried to keep my
experiments as fair as possible by keeping all the rest of the amp the same
and only changing the output iron configuration.
I know it is very much a personal thing, but the first time I turned on my
first parallel feed amp I knew that it was better and better by a lot. There
is an organic quality to PF( parallel feed) that really grabs me. This was
using a 30H power supply choke and a Z565 Dynaco PP output as well! I
compared this output setup live against a SE 2.5K Hammond 1627 in the same
amp with 7 other listeners from our club at my house and the consensus was
unanimously with the PF. I now run VV32s with PF output for 12W and am very
happy with the amps. I would encourage you to try out PF with any PP
transformer and ~4uF caps that you have. Use your SE transformer as the
plate load. The different quality of PF sound compared to SE sound will
immediately be evident and then you can decide for yourself if it's for you.
Gordon raised the coupling cap problem and the sound of this configuration
is very much affected by the cap. I have played around with a good number of
caps and have concluded that vintage oil/paper is far and away better then
film. The great thing is that oilers in the 4uF/600V range are almost given
away at swap meets, everyone looking for oil caps in larger sizes/voltages.
I do not like the sound of Solen PP film caps AT ALL in this use, and can
hear the cap immediately in amps that use them. Save your money and get some
motor run caps in you don't like oilers. A friend of mine in the Midwest
claims results better then oilers using stacked Black Gate 'N' non polar
electrolytics but I have not heard this combination personally.
A consideration with cap choices when contemplating PF, is that the AC
signal from the plate goes through the coupling cap, the primary winding of
the output transformer and then can be returned directly back to the output
tube cathode. Notice that the cathode resistor bypass cap is now out of the
signal path? Some guys don't even bother with a cathode bypass cap at all.
So I would argue that PF does not actually add a cap to the signal path at
all. It replaces a large expensive electrolytic cap with a small high
quality oiler. How can this not be a good thing?!
Regards, David
-----Original Message-----
From: James Melhuish [mailto:james@melhuish.org]
Sent: Wednesday, March 22, 2000 2:02 Pm
To: Joelist
Subject: [JN] Parallel feed helps power output?
Hi all,
Sorry if this question has been done over before. I have read several
references (sorry forgot where) that said parallel feed topologies seem
to give more power than standard single ended output transformers. Iou
believe the quality of the bass was most noticeable, a parallel feed 45
apparently had more bass oomph than a standard single ended 2A3.
What is the consensus here? Would parallel feed buy you more power when
dealing with little output tubes like the 1626?
Has anyone particular likes or dislikes with parallel feed outputs, and
which output tubes seem to like parallel feed and which don't?
James
- --
James Melhuish
mailto:james@melhuish.org
http://melhuish.org
=========================================================================
From: "Phil Sieg" <psieg@nxs.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Wed, 22 Mar 2000 18:12:01 -0500
Source: Sound Digest Archive v02.n491
Hi James,
Well, I'm in the pro parallel feed camp. And it's likely my parafeed 45s
you are referencing.
Parallel feed doesn't give more power; the 45s still rate at 1.5W at
clipping. I think there are three things going on with the this particular
execution of parallel feed topology that allow it to control a 97.5 dB
speaker so well with the extraordinary bass response.
One, plate loading the 45 with a substantial choke (40H) keeps DC off the
OPT and permits to have to deal with only the AC music signal. Two, I've
use John Camille's constant current source to load the plate of the 417A
driver. The C4S load presents an impedance of around 5 MOHm so the 417A
operates near its theoretical mu of 43. Finally, I use an 83 for
rectification which has a constant voltage drop across a wide range of
current draw rather than the rather precipitous drop at high current draw
associated with high vacuum rectifiers. The latter two have nothing to do
with parafeed, of course.
One objection to parafeed is the use of a cap to keep DC off the OPT
primary. One configuration hangs the cap (in this case a 10 uF Aerovox oil)
off the ground leg of the OPT primary, shunting DC to ground. This still
achieves the goal of (almost) keeping the OPT free of DC without putting the
cap in the direct signal path.
I've heard a conventional direct coupled 2A3 on the same speaker, and the
parafeed 45s blow it away it every area of performance. Some will suggest
that the parafeed topology will produce an artifical bass boost . Well,
perhaps. But no one who has heard the amps with the speakers thinks the
bass is out of proportion to the rest of the frequency range.
In fact, at the Dixie Bottheads get together in February (see the meeting
notes on the VALVE web page) we had 3 45-based amps - the parafeeds, an
IT-coupled amp with a conventional air-gapped OPT and an RC coupled with
recycled Dynaco Stereo 70 OPTs. Perfect opportunity to find out if
parafeed was screwing things up somehow. No One thought so. Bass was a
little tighter with the parafeed amps but no more pronounced (wrt the rest
of the audio band) than with the IT-coupled 45s (really nice amp, also BTW.)
We also had a parafeed 71A modeled after Gordon Rankin's Bugle. This amp
was without the C4S driver load. It didn't have the authority of the 45s,
yet it was capable of making the speakers play loud without giving up the
ghost - on non-complex music.
Hell, I'm going to build another pair and bi-amp with them.
Best,
Phil
- ----- Original Message -----
From: James Melhuish
To: Joelist
Sent: Wednesday, 22 March, 2000 17.02
Subject: [JN] Parallel feed helps power output?
Hi all,
Sorry if this question has been done over before. I have read several
references (sorry forgot where) that said parallel feed topologies seem
to give more power than standard single ended output transformers. I
believe the quality of the bass was most noticeable, a parallel feed 45
apparently had more bass oomph than a standard single ended 2A3.
What is the consensus here? Would parallel feed buy you more power when
dealing with little output tubes like the 1626?
Has anyone particular likes or dislikes with parallel feed outputs, and
which output tubes seem to like parallel feed and which don't?
James
- --
James Melhuish
mailto:james@melhuish.org
http://melhuish.org
=========================================================================
From: Ken Gilbert <ride5000@ride.ri.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Wed, 22 Mar 2000 20:21:57 -0500
Source: Sound Digest Archive v02.n491
>One configuration hangs the cap (in this case a 10 uF Aerovox oil)
>off the ground leg of the OPT primary, shunting DC to ground. This still
>achieves the goal of (almost) keeping the OPT free of DC without putting the
>cap in the direct signal path
i've heard this before, and i'm not so sure i can visualise how the cap is
somehow not in the direct signal path.
put it this way--what would the opt allow to pass through itself if the cap
WEREN'T there? nothing, right? (besides capacitve coupling to the entire
secondary)... the cap "holds" the other end of the primary at AC ground. it's
doing just as much "work" as it would on the other side of the winding.
perhaps there is another explanation?
ken
=========================================================================
From: TubeGarden@aol.com
Subject: Re: [JN] Parallel feed helps power output?
Date: Wed, 22 Mar 2000 20:27:12 EST
Source: Sound Digest Archive v02.n491
In a message dated 3/22/00 4:05:03 PM US Mountain Standard Time,
waudio@cinti.net writes:
> Dislikes, the CAP....
>
> Gordon
>
Greets Jeets Neets!
I am using a GE 22.5 uF 280 Vac oil/paper cap under my parafeed opts. It is
very pleasant. $4.00 at the reclamation bldg.
Happy Ears!
Al B^}
=========================================================================
From: "Phil Sieg" <psieg@nxs.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Wed, 22 Mar 2000 22:08:23 -0500
Source: Sound Digest Archive v02.n491
David,
>>Sonically,I think there is top to bottom an increase in clarity without
any edge being
introduced. <<
I agree with your observation. Conventional SE (most at least) sounds
somewhat pallid by comparison.
>>I know it is very much a personal thing, but the first time I turned on my
first parallel feed amp I knew that it was better and better by a lot. There
is an organic quality to PF( parallel feed) that really grabs me. <<
Undoubtably true, particularly through high sensitivity drivers. It's just
more "they are here"than any other SE topology I've heard.
>>Gordon raised the coupling cap problem and the sound of this configuration
is very much affected by the cap. I have played around with a good number of
caps and have concluded that vintage oil/paper is far and away better then
film.<<
Yup, got it in one.
>>A consideration with cap choices when contemplating PF, is that the AC
signal from the plate goes through the coupling cap, the primary winding of
the output transformer and then can be returned directly back to the output
tube cathode. Notice that the cathode resistor bypass cap is now out of the
signal path? Some guys don't even bother with a cathode bypass cap at all<<
Another approach is to hang the cap off the ground leg of the OPT primary
and tie it to the top of the cathode bias resistor. I'm going to try this
in my parafeed preamp currently on the bench. Reportedly, it's a stunner.
As far as the cathode bypass cap goes, I dunno. I think it's still needed
on the output tube, maybe less so on the driver if you use a parafeed
interstage or load the driver plate with a high impedance CCS.
Phil
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Parallel feed helps power output?
Date: Wed, 22 Mar 2000 22:32:42 GMT
Source: Sound Digest Archive v02.n491
Hi there,
>I believe the quality of the bass was most noticeable, a parallel feed 45
>apparently had more bass oomph than a standard single ended 2A3.
Leaving aside the obvious point about differences in valves (I noted repeate
comments that the 45 sounds fuller than the 2A3), comparing two different
Amplifiers is not easy. OFten the differences in PSU Design are greater than
the differences in valves or output Transformers.
As to "does using a retard coil and a capacitor coupled normal Transformer
give more power?"
It depends. A parafeed Trannie may have a lower insertion loss, giving you
perhaps 0.5 to 1db more power, all else being equal. But you can also get
classic SE Transformers with a Low Insertion loss.
BTW, in my Amplifier I found very littel difference between 2A3 and 300B, on
all counts. Yes, they are different, but the 2A3 kicks as hard and as low as
a 300B. The 2A3 has a slightly brighter tone, a little more transparency,
but to my ears and with my Speakers the balance is a little tinny overall.
With the Hoerning Perikles I'm reviewing at the moment, the 2A3 seems the
better choice, but the Perikles sound slightly dark anyway.
Later T
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=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Wed, 22 Mar 00 18:15:15 -0500
Source: Sound Digest Archive v02.n491
James,
Simply the transformer has less losses so you get a tad bit more power.
>What is the consensus here? Would parallel feed buy you more power when
>dealing with little output tubes like the 1626?
PF works best in my opinion with low power (under 3W) and high power
(above 32W). The low because you are looking for the most out of the
device. The high because of diminishing returns from a std direct feed
units.
>Has anyone particular likes or dislikes with parallel feed outputs, and
>which output tubes seem to like parallel feed and which don't?
Dislikes, the CAP....
Gordon
=====> Wavelength Audio <=====
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "Dave Slagle" <dslagle@earthlink.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 00:03:15 -0500
Source: Sound Digest Archive v02.n491
hey... i hope its safe to offer a differing opinion here...
>>>Sonically,I think there is top to bottom an increase in clarity without
> any edge being
> introduced. <<
>
> I agree with your observation. Conventional SE (most at least) sounds
> somewhat pallid by comparison.
i have tried "non-optimal" PF on several occasions... and initially
everything seemed better, but after time i noticed that although everything
by itself sounded better, the entire picture was less pleasurable...
i remember when a fellow list member brought over a pair of his amps.. a
single darling, and a PF darling... all his friends preferred the added
power (punch) and bass for the PF darling... and i heard this too... for a
few minutes it grabbed my attention.. it was a quality anyone could hear..
it said here i am... listen to my perfect bass... my what crisp treble...
but thats not my style.,,, and its not what i want to listen to for hours at
a time... i will agree with the overall correctness of the top to bottom
sound... my problem is... it doesn't seem to fit together...sorta like when
i biamped with SS and tubes... my stereogeek friends were impressed... i
wasn't... today its just the opposite.... i'm happy... people who come in
for a 5 minute listen are underwhelmed....others leave happy.... the ones
who leave happy are the ones i listen too...
take the above with the caveat... that i listen through lowthers and have
numerous other wacky things... at the moment a pair of ravens aimed
backwards to the center at a 45 degree angle... 4 mic cap in series...
nothing else... it was down and dirty... but has done more than any earlier
attempts with a front firing focal.... i would hate to see the phase
allignment dilemma this would cause...
nah... thats enough...
=========================================================================
From: "Darryl Lock" <dklock@ieee.org>
Subject: RE: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 14:27:37 +1000
Source: Sound Digest Archive v02.n491
> One objection to parafeed is the use of a cap to keep DC off the OPT
> primary. One configuration hangs the cap (in this case a 10 uF
> Aerovox oil)
> off the ground leg of the OPT primary, shunting DC to ground.
I must not understand where you mean. How does a cap shunt DC, surely it
blocks DC?
> This still
> achieves the goal of (almost) keeping the OPT free of DC without
> putting the
> cap in the direct signal path.
>
How is that not in the direct signal path?
Do you have an url for a diagram to make it clearer what you meant?
Darryl
=========================================================================
From: "Darryl Lock" <dklock@ieee.org>
Subject: RE: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 14:35:47 +1000
Source: Sound Digest Archive v02.n491
> I would encourage you to try out PF with any PP
> transformer and ~4uF caps that you have. Use your SE transformer as the
> plate load.
Do you load down the secondary of the SE transformer with an appropriate
impedance when you use them as a plate load like this?
Darryl
=========================================================================
From: James Melhuish <james@melhuish.org>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 10:09:21 -0500
Source: Sound Digest Archive v02.n492
Thanks all!
Just FYI, if anyone wants to see circuit diagrams of parallel feed, read
the Paul Joppa article "Twelve Ways to Parafeed" in VALVE Vol 6, No 5,
1999 (at http://www.bottlehead.com/).
James
- --
James Melhuish
mailto:james@melhuish.org
http://melhuish.org
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 11:38:27 -0500
Source: Sound Digest Archive v02.n492
"J. Gordon Rankin" wrote:
>
>
> 2) The cap before or the cap after (i.e. Plate or Ground). Don't ask me
> why because in all engineering experience there should not be a
> diference. But there is, cap grounded to me sounds much better.
> Hypathetically I would say that maybe because the cap should look shorted
> in the AC frame. If you put it on the plate, you are going through the
> cap. If you place it in the ground frame, it looks like a short,
> Hypathetically...
With the cap "before", there's no DC on the primary output tranny. With
the cap grounded, the primary is "biased" by the B+ voltage. The
engineering models are indeed identical, but there could, for example,
be some dielectric effects on the windings of the tranny.
JL
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 16:54:08 GMT
Source: Sound Digest Archive v02.n492
Hi there,
>1) Many suggest that the PF lowers the noise floor because of the large
>loading choke. I would tend to disagree with this statement because most of
>the noise is coming from the input stage in either PF or DF (Direct Feed).
Agreed. Normally PSU Line ripple should be no issue.
>2) The cap before or the cap after (i.e. Plate or Ground). Don't ask me why
>because in all engineering experience there should not be a diference. But
>there is, cap grounded to me sounds much better.
So I hear. I also am not sure, but perhaps we can explain things with
leakage capacitance to the Chassis?
On the Anode we have capacitance to chassis, loading it at high frequencies.
On the other side we ain't.... After all, we orient (normally) X-formers for
lowest leakage too....
>3) Cap size... Man this is a hard one, but in deeveloping the Mercury
>amps I spent a lot of time fooling with size. I found the lower the value
>(without drastic phase problems in the bass) made the cap type less
>influential. I typically use high inductance low capacitence and this works
>for me.
Again, I find this to hold true on a very general level. And as usual,
smaller value cap's are physically smaller and tend to allways sound better
in Midraneg and Treble, at least that is my experience.
Later Thorsten
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=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 00 11:23:55 -0500
Source: Sound Digest Archive v02.n492
Gang,
Just want to clear up a few things:
1) Many suggest that the PF lowers the noise floor because of the large
loading choke. I would tend to disagree with this statement because most
of the noise is coming from the input stage in either PF or DF (Direct
Feed).
2) The cap before or the cap after (i.e. Plate or Ground). Don't ask me
why because in all engineering experience there should not be a
diference. But there is, cap grounded to me sounds much better.
Hypathetically I would say that maybe because the cap should look shorted
in the AC frame. If you put it on the plate, you are going through the
cap. If you place it in the ground frame, it looks like a short,
Hypathetically...
3) Cap size... Man this is a hard one, but in deeveloping the Mercury
amps I spent a lot of time fooling with size. I found the lower the value
(without drastic phase problems in the bass) made the cap type less
influential. I typically use high inductance low capacitence and this
works for me.
Gordon
=====> Wavelength Audio <=====
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: David Home <DHome@creo.com>
Subject: RE: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 09:39:41 -0800
Source: Sound Digest Archive v02.n493
Hi Phil. Well I guess I'm preaching to the converted! You don't seem to need
any convincing. 8^)
I did not put the cap below the output transformer in my amps because my
design has a plate voltage of 710V. The primary winding to grounded case
potential of the output would then exceed the voltage that Magnequest will
warranty. At the price of the nickel TFA2004s, I can live with the slight
loss!
I'm told that without the bypass cap on the cathode resistor, there will be
some phase shift in the bottom octave. I tried my amps with and without the
bypass and thought that the bass was slightly 'faster' with the cap in. The
change was of the order that imagination kicks in though, I would have still
been happy without it. My speakers are flat to 25 H z. With less full
range speakers I would leave it out.
Regards, David
-----Original Message-----
From: Phil Sieg [mailto:psieg@nxs.net]
Sent: Wednesday, March 22, 2000 7:08 PM
To: David Home; 'James Melhuish'; Joelist
Subject: Re: [JN] Parallel feed helps power output?
David,
>>Sonically,I think there is top to bottom an increase in clarity without
any edge being
introduced. <<
I agree with your observation. Conventional SE (most at least) sounds
somewhat pallid by comparison.
>>I know it is very much a personal thing, but the first time I turned on my
first parallel feed amp I knew that it was better and better by a lot. There
is an organic quality to PF( parallel feed) that really grabs me. <<
Undoubtably true, particularly through high sensitivity drivers. It's just
more "they are here"than any other SE topology I've heard.
>>Gordon raised the coupling cap problem and the sound of this configuration
is very much affected by the cap. I have played around with a good number of
caps and have concluded that vintage oil/paper is far and away better then
film.<<
Yup, got it in one.
>>A consideration with cap choices when contemplating PF, is that the AC
signal from the plate goes through the coupling cap, the primary winding of
the output transformer and then can be returned directly back to the output
tube cathode. Notice that the cathode resistor bypass cap is now out of the
signal path? Some guys don't even bother with a cathode bypass cap at all<<
Another approach is to hang the cap off the ground leg of the OPT primary
and tie it to the top of the cathode bias resistor. I'm going to try this
in my parafeed preamp currently on the bench. Reportedly, it's a stunner.
As far as the cathode bypass cap goes, I dunno. I think it's still needed
on the output tube, maybe less so on the driver if you use a parafeed
interstage or load the driver plate with a high impedance CCS.
Phil
=========================================================================
From: "Phil Sieg" <psieg@nxs.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 12:01:38 -0500
Source: Sound Digest Archive v02.n493
Gordon,
>>1) Many suggest that the PF lowers the noise floor because of the large
loading choke. I would tend to disagree with this statement because most
of the noise is coming from the input stage in either PF or DF (Direct
Feed).<<
That is certainly the case in my amps. DC current regulated filaments and a
constant current source plate load on the 417A driver did the trick.
>>2) The cap before or the cap after (i.e. Plate or Ground). Don't ask me
why because in all engineering experience there should not be a
diference. But there is, cap grounded to me sounds much better.
Hypathetically I would say that maybe because the cap should look shorted
in the AC frame. If you put it on the plate, you are going through the
cap. If you place it in the ground frame, it looks like a short,
Hypathetically...<<
Yup. My experience also. Next step is to tie the cap to the top of the
cathode bias resistor.
>>3) Cap size... Man this is a hard one, but in deeveloping the Mercury
amps I spent a lot of time fooling with size. I found the lower the value
(without drastic phase problems in the bass) made the cap type less
influential. I typically use high inductance low capacitence and this
works for me.<<
How low is Low? And what dielectric are you using?
Best,
Phil
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 17:12:43 GMT
Source: Sound Digest Archive v02.n493
Yo John,
>With the cap "before", there's no DC on the primary output tranny. With the
>cap grounded, the primary is "biased" by the B+ voltage. The engineering
>models are indeed identical, but there could, for example, be some
>dielectric effects on the windings of the tranny.
EXCELLENT THOUGHT. I missed that. I'd say that is more likely than the
"leakage" Capacitance to chassis....
Amazing. One never stops learning. If this is so, then returning the Primary
to the Cathode (which also has usually quite a few Volz on it) should do
pretty much the same trick. I'll have to play around with that on the new
linestage ide of mine....
Later Thorsten
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=========================================================================
From: "Phil Sieg" <psieg@nxs.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 18:14:54 -0500
Source: Sound Digest Archive v02.n493
Hi Kurt,
>>I am myself working on the parafeed idea.
What I like about it is the two following observations.
>>1) The DC idle is removed from the OPT. There is several advantages with
this.
>>The major being that better low signal frequency is possible.
That's certainly true.
>>2) The transformer can be carried out in a better quality , that the one
that has to deal with the idle current as well.
>>That makes even the size of the transformer more convenient.
>>( A 212 OPT in high quality , is an realistic option , with this circuit )
>>Is is certain that the bass will be a lot better with a PF circuit.
Also allows the use of more permeable cores like nickel alloy without fear
of saturation, esp at low frequencies.
>>We have a tube parallel with a choke and a OPT in series with a cap.
>>On top on that , is as you say the cap between the windings.
>>This is INDEED a VERY complicated circuit as all is out of common phase.
Which is another reason to hang it off the ground leg of the OPT primary.
>>I am pretty sure it will be an advantage to place the signal cap between
ground and OPT primary winding.
>>However if the secondary is grounded , I am having difficult in spotting
the best approach.
Secondary is not grounded, however. There's no DC in there anymore son I
can't see the need to ground the secondary.
>>A consideration with cap choices when contemplating PF, is that the AC
signal from the plate goes through the coupling cap, the primary winding of
the output transformer and then can be returned directly back to the output
tube cathode. Notice that the cathode resistor bypass cap is now out of the
signal path? Some guys don't even bother with a cathode bypass cap at all<<
>>Woo. I am not sure I agree here though.
>>Adding just another signal path ( Time constant ) to the already much to
many , gives me the creep.
>>( Anyway it is still in the signal path )
I think it can work at the line stage level where there is no cathode bypass
cap. I'll let you know beccause I'm going to try it on the preamp I'm
currently building. If it screws things up, back to ground with the
parafeed cap.
>>So I think the conclusion to the parafeed idea could be the usual..."There
is no such thing as free meals"...
>>We do gain with a better OPT and better conditions for this. But
unfortunately we loose the simplicity of the conventional stage.
It's always tradeoffs. It seems heuristically that PF can be beneficial
with low power triodes (10, 45, 2A3) in that in enables - or at least
"seems" to enable - use of the output stages with speakers < 100 dB
efficient. Perhaps that an illiusion I cling to for comfort ;-).
>>As soon as I am done with my PF outputstage , I will report back to the
list , if anyone is interested.
Kurt, I am most certainly interested.
Phil
=========================================================================
From: James Melhuish <james@melhuish.org>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 18:54:22 -0500
Source: Sound Digest Archive v02.n493
Would making the normal SE transformer exceptionally large and expensive
reduce the possibility of saturation and improve bass performance.
After all, if we are paying for two (plate choke and output
transformer), why not pay for one super transformer?
James
- --
James Melhuish
mailto:james@melhuish.org
http://melhuish.org
=========================================================================
From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 2000 22:48:28 +0300
Source: Sound Digest Archive v02.n493
- --------------6A25096B88820E69C9520229
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Dear Phil and other Joes.
I am myself working on the parafeed idea.
What I like about it is the two following observations.
1) The DC idle is removed from the OPT. There is several advantages with this.
The major being that better low signal frequency is possible.
2) The transformer can be carried out in a better quality , that the one that
has to deal with the idle current as well.
That makes even the size of the transformer more convenient.
( A 212 OPT in high quality , is an realistic option , with this circuit )
Is is certain that the bass will be a lot better with a PF circuit.
What I do not like is the following.
While I am not really worried about the big anode choke , the high current takes
care that such is not hard to produce , and neither am I to worried about the
necessary cap.
( Can be avoided by hanging the OPT in a split supply. But that would lead to
other problems )
What I am worried about is the very complicated circuit that suddenly is placed
, instead of the simple conventional anode load.
We have a tube parallel with a choke and a OPT in series with a cap.
On top on that , is as you say the cap between the windings.
This is INDEED a VERY complicated circuit as all is out of common phase.
Phil Yates or some other skilled mathematician , might solve the picture of this
mess. I gave up at three unknown.
The frequency in which all these time constants start to mess with one another
will depend upon the actual circuit and components used.
But they will be within the audio range no matter what we do.
Regarding the cap on top of the OPT or direct to ground , this will affect the
picture in different ways.
The ungrounded secondary will be quite nervous while AC signals passes the
primary path.
It will flow opposite the current , and affect the audio output.
I am pretty sure it will be an advantage to place the signal cap between ground
and OPT primary winding.
However if the secondary is grounded , I am having difficult in spotting the
best approach.
Testing it with sines will not show a thing. But pulses or squares will reveal
the beast.
> >>Gordon raised the coupling cap problem and the sound of this configuration
> is very much affected by the cap. I have played around with a good number of
> caps and have concluded that vintage oil/paper is far and away better then
> film.<<
>
> Yup, got it in one.
Me to.
> >>A consideration with cap choices when contemplating PF, is that the AC
> signal from the plate goes through the coupling cap, the primary winding of
> the output transformer and then can be returned directly back to the output
> tube cathode. Notice that the cathode resistor bypass cap is now out of the
> signal path? Some guys don't even bother with a cathode bypass cap at all<<
Woo. I am not sure I agree here though.
Adding just another signal path ( Time constant ) to the already much to many ,
gives me the creep.
( Anyway it is still in the signal path )
BTW , someone mentioned that the cap "almost" removed the DC current from the
OPT....
We have to say that it removes it entirely. I do not think that such bad
electrolytics are even possible to dig up on the lowest thinkable budget ;-)
Further I believe that all good wide band transformers need to have a small air
gap. As far as I know this is one of the main "secrets" in high quality
audio transformers.
But I also know that the size of this gap is extremely critical , that might be
the reason that some ignores it ?
> As far as the cathode bypass cap goes, I dunno. I think it's still needed
> on the output tube, maybe less so on the driver if you use a parafeed
> interstage or load the driver plate with a high impedance CCS.
Well , only thing good it does is to keep the necessary driver signal down.
( Amplification in other words )
Having say 10 to 100 Ohms unbypassed down here , would ease some of the related
difficulties in this circuit mess.
( Active bias would ofcourse be necessary to assure proper bias , but that is no
problem in my opinion )
So I think the conclusion to the parafeed idea could be the usual..."There is no
such thing as free meals"...
We do gain with a better OPT and better conditions for this. But unfortunately
we loose the simplicity of the conventional stage.
Whatever is the best will depend upon circuit , design , load (speakers ) , the
remaining system and personal taste...
Oh , another thing. Someone earlier claimed that the parafeed circuit influenced
the previous stages.
I do think that this is a wild goose. It does not change the stages previous to
it more than any other circuits.
It might if pushed into grid current act a little different to the driver than
the conventional circuit , but that is it.
But maybe it was meant in another way.
As soon as I am done with my PF outputstage , I will report back to the list ,
if anyone is interested.
I belive I will start with a 572-3 and then slowly work up to a cool 212 :-)
Maybe I will even bring the 572 conventional and PF to the summer festival ;-)
- - Kurt
- --------------6A25096B88820E69C9520229
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit
<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
<br>
<br>
<p>Dear Phil and other Joes.
<p>I am myself working on the parafeed idea.
<br>What I like about it is the two following observations.
<p>1) The DC idle is removed from the OPT. There is several advantages
with this.
<br>The major being that better low signal frequency is possible.
<p>2) The transformer can be carried out in a better quality , that the
one that has to deal with the idle current as well.
<br>That makes even the size of the transformer more convenient.
<br>( A 212 OPT in high quality , is an realistic option , with this circuit
)
<p>Is is certain that the bass will be a lot better with a PF circuit.
<p>What I do not like is the following.
<p>While I am not really worried about the big anode choke , the high current
takes care that such is not hard to produce , and neither am I to worried
about the
<br>necessary cap.
<br>( Can be avoided by hanging the OPT in a split supply. But that would
lead to other problems )
<p>What I am worried about is the very complicated circuit that suddenly
is placed , instead of the simple conventional anode load.
<p>We have a tube parallel with a choke and a OPT in series with a cap.
<br>On top on that , is as you say the cap between the windings.
<br>This is INDEED a VERY complicated circuit as all is out of common phase.
<br>Phil Yates or some other skilled mathematician , might solve the picture
of this mess. I gave up at three unknown.
<p>The frequency in which all these time constants start to mess with one
another will depend upon the actual circuit and components used.
<br>But they will be within the audio range no matter what we do.
<p>Regarding the cap on top of the OPT or direct to ground , this will
affect the picture in different ways.
<br>The ungrounded secondary will be quite nervous while AC signals passes
the primary path.
<br>It will flow opposite the current , and affect the audio output.
<br>I am pretty sure it will be an advantage to place the signal cap between
ground and OPT primary winding.
<p>However if the secondary is grounded , I am having difficult in spotting
the best approach.
<br>Testing it with sines will not show a thing. But pulses or squares
will reveal the beast.
<blockquote TYPE=CITE>>>Gordon raised the coupling cap problem and the
sound of this configuration
<br>is very much affected by the cap. I have played around with a good
number of
<br>caps and have concluded that vintage oil/paper is far and away better
then
<br>film.<<
<p>Yup, got it in one.</blockquote>
Me to.
<blockquote TYPE=CITE>>>A consideration with cap choices when contemplating
PF, is that the AC
<br>signal from the plate goes through the coupling cap, the primary winding
of
<br>the output transformer and then can be returned directly back to the
output
<br>tube cathode. Notice that the cathode resistor bypass cap is now out
of the
<br>signal path? Some guys don't even bother with a cathode bypass cap
at all<<</blockquote>
Woo. I am not sure I agree here though.
<br>Adding just another signal path ( Time constant ) to the already much
to many , gives me the creep.
<br>( Anyway it is <i>still</i> in the signal path )
<p>BTW , someone mentioned that the cap "almost" removed the DC current
from the OPT....
<br>We have to say that it removes it entirely. I do not think that such
bad electrolytics are even possible to dig up on the lowest thinkable budget
;-)
<p>Further I believe that all good wide band transformers need to have
a small air gap. As far as I know this is one of the main "secrets" in
high quality
<br>audio transformers.
<br>But I also know that the size of this gap is extremely critical , that
might be the reason that some ignores it ?
<br>
<blockquote TYPE=CITE>As far as the cathode bypass cap goes, I dunno.
I think it's still needed
<br>on the output tube, maybe less so on the driver if you use a parafeed
<br>interstage or load the driver plate with a high impedance CCS.</blockquote>
Well , only thing good it does is to keep the necessary driver signal down.
<br>( Amplification in other words )
<br>Having say 10 to 100 Ohms unbypassed down here , would ease some of
the related difficulties in this circuit mess.
<p>( Active bias would ofcourse be necessary to assure proper bias , but
that is no problem in my opinion )
<p>So I think the conclusion to the parafeed idea could be the usual..."There
is no such thing as free meals"...
<br>We do gain with a better OPT and better conditions for this.
But unfortunately we loose the simplicity of the conventional stage.
<br>Whatever is the best will depend upon circuit , design , load (speakers
) , the remaining system and personal taste...
<p>Oh , another thing. Someone earlier claimed that the parafeed circuit
influenced the previous stages.
<br>I do think that this is a wild goose. It does not change the stages
previous to it more than any other circuits.
<br>It might if pushed into grid current act a little different to the
driver than the conventional circuit , but that is it.
<br>But maybe it was meant in another way.
<p>As soon as I am done with my PF outputstage , I will report back to
the list , if anyone is interested.
<br>I belive I will start with a 572-3 and then slowly work up to a cool
212 :-)
<br>Maybe I will even bring the 572 conventional and PF to the summer festival
;-)
<p>- Kurt
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br>
<br> </html>
- --------------6A25096B88820E69C9520229--
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Thu, 23 Mar 00 12:33:39 -0500
Source: Sound Digest Archive v02.n493
>With the cap "before", there's no DC on the primary output tranny. With the
>cap grounded, the primary is "biased" by the B+ voltage. The engineering
>models are indeed identical, but there could, for example, be some
>dielectric effects on the windings of the tranny.
John,
True, and from what I understand with people using parafeed in some
instances (this one cracks me up: Cary 805C using the output as a choke,
TFA2004 pin strip, ground cap GE motor start) that may take the
trasformer out because the dielectric will not handle the voltage (in
this case 950V, not too say that the fact that this is only good to 12W).
Gordon
=====> Wavelength Audio <=====
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: Paul Joppa <pdjoppa@home.com>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 00:20:32 -0800
Source: Sound Digest Archive v02.n493
"J. Gordon Rankin" said
...
> 3) Cap size... Man this is a hard one, but in deeveloping the Mercury
> amps I spent a lot of time fooling with size. I found the lower the value
> (without drastic phase problems in the bass) made the cap type less
> influential. I typically use high inductance low capacitence and this
> works for me.
I have found that one can use PSpice or an equivalent to model the
effects (I presented this at VSAC '98 but it's not otherwise published
yet). It is certainly possible to get some resonances (yes, I have
done it!), but there's usually a broad range of capacitance for which
the response is well-behaved, leaving only a few subtle effects which
one might do best to tune by ear. A few things are surprisingly
important though:
* the power supply filter must be modelled as well as the parafeed
output stage - I found some severe resonances at 2Hz for instance,
discovered through measurement and only seen in the model after this
was included. To be safely ignored, the PS capacitor must be huge -
perhaps 1,000 uF or more.
* In addition to the simple frequency response, it is valuable to plot
the AC current through the tube and the plate loading choke. It is
very easy to get a wonderfully flat bass response at small signal
levels, only to suffer from severe power bandwidth limitations.
Generally there is a tradeoff here, requiring many iterations to
arrive at a few practical alternatives which then can be listened to.
The tradeoffs involve the effects of core saturation and tube
linearity, and the audible efects are difficult to predict because
they are sensitive to the particular iron and tube used.
- -Paul Joppa
=========================================================================
From: Grover Gardner <groverg@postoffice.att.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 00:25:39 -0500
Source: Sound Digest Archive v02.n493
At 6:54 PM -0500 3/23/00, James Melhuish wrote:
>Would making the normal SE transformer exceptionally large and expensive
>reduce the possibility of saturation and improve bass performance.
>After all, if we are paying for two (plate choke and output
>transformer), why not pay for one super transformer?
From what little I've gleaned about transformers, it appears that you
reach a point of diminishing returns. The larger the SE OPT, the
more inductance, capacitance, flux etc. all start to come into
conflict with each other. Am I wrong?
- -------
Grover Gardner
groverg@postoffice.att.net
=========================================================================
From: tube@jump.net
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 00:32:24 -0600
Source: Sound Digest Archive v02.n493
"J. Gordon Rankin" wrote:
[Snip]
> 2) The cap before or the cap after (i.e. Plate or Ground). Don't ask me
> why because in all engineering experience there should not be a
> diference. But there is, cap grounded to me sounds much better.
> Hypathetically I would say that maybe because the cap should look shorted
> in the AC frame. If you put it on the plate, you are going through the
> cap. If you place it in the ground frame, it looks like a short,
> Hypathetically...
This one bothered me for a year or so, because what everyone says is
true; the same current goes thru the cap regardless of its position.
Since it sounds better if the cap is grounded regardless of theory,
something MUST be happening that the theory is missing. The only thing
I have come up with is this: When the cap is grounded, it doesn't
"move" much in an electrostatic sense. Especially if the outer foil is
grounded, the cap is effectively shielded from stray electromagnetic
fields. If, however, the cap is between the tube and the transformer,
it is moving up and down literally hundreds of volts at extremely high
speed. In effect, it is "exposed".
We can test this by simply shielding the cap, preferably with a foil
that shields both electrostatic AND magnetic fields. If it sounds a lot
better with the shield, we're on to something! And no I still don't
have my own amp, so I haven't tested it, but ... Michael Percy sells
some "TI foil" that should do the trick. It might even be helpful to
elevate the cap away from any dielectrics, like PC boards.
Notice also that if this is true (that shielding improves the sound),
that this would also apply to interstage coupling caps. Perhaps this is
one reason that interstage transformers tend to sound better than caps.
I am certain, however, that it is not the only reason.
As for not needing a cathode bypass cap, the only sources of AC
current through the cathode resistor when the PF cap is tied to the
cathode are variations in current thru the PF choke (only at low freq)
and current thru the grid. This latter does come into play during
positive peaks, of course, but since it ONLY occurs during positive
peaks, it will tend to charge the cathode bypass cap. I suspect a DC
bypass--even a crude one--would be better, but with a big cap the truth
may be that it really doesn't matter. Anyway, during positive grid
voltage peaks and at low frequencies (where the choke starts to crap
out), a cathode resistor bypass cap might well improve things.
Oops! Just remembered that the input capacitance also goes thru the
grid. All the time, not just during positive grid voltages (and from
there thru the cathode resistor). A very small, very high quality cap
would obviously be better for this than a poor sounding big cap. Don't
know which would have the bigger effect, positive peaks, which need a
big cap, or the input capacitance, which can use a small one. I plan
to use a DC shift between the tubes, myself, which will allow me to
ground the output tube (end of debate) and use an autoformer as well,
so I have largely given up caring about whether to use a cathode
resistor bypass cap.
In both cases, the problem of how to make a cap from tube to
transformer sound as good as a grounded cap remains. At least, if
you want to use an autoformer, or don't want too much voltage
across your transformer.
Phil Yates
>
> 3) Cap size... Man this is a hard one, but in deeveloping the Mercury
> amps I spent a lot of time fooling with size. I found the lower the value
> (without drastic phase problems in the bass) made the cap type less
> influential. I typically use high inductance low capacitence and this
> works for me.
>
> Gordon
>
> =====> Wavelength Audio <=====
> mailto:waudio@cinti.net
> http://www.WavelengthAudio.com
> ph.fx. 513-271-4186 USA
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 09:13:28 -0500
Source: Sound Digest Archive v02.n494
Kurt Steffensen wrote:
>
> Oh , another thing. Someone earlier claimed that the parafeed circuit
> influenced the previous stages.
> I do think that this is a wild goose. It does not change the stages
> previous to it more than any other circuits.
> It might if pushed into grid current act a little different to the
> driver than the conventional circuit , but that is it.
> But maybe it was meant in another way.
There is a subtle but easily measurable effect on previous stages when
using a parafeed output: Less of the output signal shows up on the power
supply.
Generally speaking, the net plate inductance seen by the output tube is
the plate choke inductance in parallel with the primary inductance of
the output tranny. It's [generally] more cost effective to use a plate
choke whose inductance is greater than that of the output tranny
primary. In addition, when using a "normal" SE output tranny, the load
seen by the output tube, say 3-5K in the case of a 300B, exists between
the plate of the tube and the power supply. However, in parafeed, that
3-5K exists between the plate and ground (or the cathode in the case of
an Ultrapath implementation). In parafeed, the impedance between the
plate and the power supply is set by the plate choke inductance alone,
not the reflected load impedance. Therefore, the plate choke presents a
much higher impedance for any signal current trying to go towards the
power supply.
This is easily measurable. Take a normal SE output, crank up the power
at 1kHz, and (with a scope of course) measure the 1kHz component on the
power supply. Do the same thing with parafeed and you'll see much much
less 1kHz. The less of this signal voltage on the power supply, the less
energy rattling around that can then propagate back to earlier stages
and intermodulate the real signal. Power supplies will tend to filter
things out, but not completely and not without delay. And we all know
that even though there's stuff rattling around at -80dB, we can still
hear it, right?
JL
>
> As soon as I am done with my PF outputstage , I will report back to
> the list , if anyone is interested.
> I belive I will start with a 572-3 and then slowly work up to a cool
> 212 :-)
> Maybe I will even bring the 572 conventional and PF to the summer
> festival ;-)
>
> - Kurt
>
>
>
>
>
>
>
>
>
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 09:20:16 -0500
Source: Sound Digest Archive v02.n494
James Melhuish wrote:
>
> Would making the normal SE transformer exceptionally large and expensive
> reduce the possibility of saturation and improve bass performance.
> After all, if we are paying for two (plate choke and output
> transformer), why not pay for one super transformer?
FWIW, I use FS-030's in my "normal" SE amp, which support low-distortion
bass down to something like 7Hz from a 300B. As a result, my experiments
with parafeed have not created the dramatic improvement in bass response
that many report. On a philosophical basis, I too prefer the "one part
is better than 3" approach. And I can't get over that cap. Without
exception, every time I remove a cap or replace one with a tranny (IT
for example), the sound improves. At least to my ears, but YMMV.
JL
>
> James
> --
> James Melhuish
> mailto:james@melhuish.org
> http://melhuish.org
=========================================================================
From: "Phil Sieg" <psieg@nxs.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 10:07:33 -0500
Source: Sound Digest Archive v02.n494
Guido,
>>Did anyone among you consider a (silicon) current source instead of series
choke on top of the lower device ?
Yes, I am using John Camille's C$s source as a plate load.
>>A well designed current source has a high impedance over a wide bandwidth.
That it do.
>>Disadvantage is the additional dissipation.....
>>Advantage is higher supply rejection
Yes, agreed.
I believe the improvment in mu -to the theoretical maximum - given by the
C4S is the main reason, parafeed output aside, that a single 45 output stage
can so successfully drive 97.5 dB, 8 Ohm speakers full range.
Phil
=========================================================================
From: dslagle@earthlink.net (dave slagle)
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 11:56:44 -0500
Source: Sound Digest Archive v02.n494
>I still think PF is good for low output under 5W and above 32W (where the
>diminishing returns for the output and direct current make the
>transformer well... oversized).
I may buy the above 32W... but below 5W??? goind down in size should only
improve a trannie... and if you go down in power... if this argument holds
true... something magical must happen between 5 and 32W.... the way i
understand it... the higher in power you go the more your SE compromises
come into play...
now if you are referring to parafeed works better for small power higher Rp
tubes (45) there may be some logic... since the higher Rp requires more
inductance.
why not take out the hugest requirement and bi-amp and get your trannies
done for the job.... its odd that the holy grail of 10 octives is the major
compromise (that is it forces all the others) and splitting the range
between a bass trannie and a "the rest" trannie for the most part makes the
rest of the arguments moot.
Jim flowers referred to this in his valve articles... and i have yet to see
it done... i guess it makes too much sense...
while preferring SE on outputs... the idea of parafeed seems plausible on
earlier stages... but again i have to ask... why use a transformer?
actually i have been thinkin about it a bit... why use an autoformer?
why not tap your plate choke and cap couple with a grid choke???
well now i guess you guys all know whats on my winding list.....
time to unsolder the noise amp.... and add some clip leads.. somehow they
just make the sound so much more dangerous...
dave
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 13:14:51 +0100
Source: Sound Digest Archive v02.n494
Hi all,
I like the parafeed discusion. I would like to raise the following:
Did anyone among you consider a (silicon) current source instead of series
choke on top of the lower device ?
A well designed current source has a high impedance over a wide bandwidth.
Disadvantage is the additional dissipation.....
Advantage is higher supply rejection
In addition I would like to mention the SEPP output stage as introduced by
Philips, using EL86 in kind of SRPP circuit. It has cap coupling to he
output transformer and complex circuitry to obtain the G2 signals for both
valves, as these are penthodes.....
Peter Sikking has mentionned an amp with this principle, type nr is AG
9018, if I am right.
Have fun
Guido
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 18:39:30 +0100
Source: Sound Digest Archive v02.n494
>Can someone tell me why this rejects noise from the power supply? It is
>active...
Active or not, it may show a very high impedance (if well designed)
compared to the plate of the triode output tube.
>I have always gotten better results from a choke.
That maybe, but can be for several reasons.
Have fun
=
Guido
>Gordon
>
>=====> Wavelength Audio <=====
>mailto:waudio@cinti.net
>http://www.WavelengthAudio.com
>ph.fx. 513-271-4186 USA
>
>
>
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 00 10:01:38 -0500
Source: Sound Digest Archive v02.n494
>FWIW, I use FS-030's in my "normal" SE amp, which support low-distortion
>bass down to something like 7Hz from a 300B. As a result, my experiments
>with parafeed have not created the dramatic improvement in bass response
>that many report. On a philosophical basis, I too prefer the "one part
>is better than 3" approach. And I can't get over that cap. Without
>exception, every time I remove a cap or replace one with a tranny (IT
>for example), the sound improves. At least to my ears, but YMMV.
John,
I totally agree... But where you buy better bass is in the lower output
tubes. Take for example the 030, for the 300B that has just tons of
inductance say 40H. Now take like the ES050 or the DS050, they have
relatively less inductance than is needed for a 45 or VT52.
So with PF, you can use a big *^&$% choke and get a little more on the
bottom end.
I still think PF is good for low output under 5W and above 32W (where the
diminishing returns for the output and direct current make the
transformer well... oversized).
Gordon
PS: Agreed with the transformer approach. See my Napoleon NCE,
transformers from one end to the other.
=====> Wavelength Audio <=====
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 00 10:44:25 -0500
Source: Sound Digest Archive v02.n494
>Yes, I am using John Camille's C$s source as a plate load.
Can someone tell me why this rejects noise from the power supply? It is
active...
I have always gotten better results from a choke.
Gordon
=====> Wavelength Audio <=====
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 00 13:58:48 -0500
Source: Sound Digest Archive v02.n494
Dave,
>now if you are referring to parafeed works better for small power higher Rp
>tubes (45) there may be some logic... since the higher Rp requires more
>inductance.
Yep, higher Rp requires more inductance....
>why not take out the hugest requirement and bi-amp and get your trannies
>done for the job.... its odd that the holy grail of 10 octives is the major
>compromise (that is it forces all the others) and splitting the range
>between a bass trannie and a "the rest" trannie for the most part makes the
>rest of the arguments moot.
Simple the only good bi-amp system is with two of the exact same
amplifiers. This is the only way you can secure the same sonic signature
(was one of my senior projects). At that point what's the point.
I still say, low watt plus subs under 100Hz is the best. Not perfect but
pretty close.
Gordon
=====> Wavelength Audio <=====
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "Hugh R. Dean" <aspen@alphalink.com.au>
Subject: Re: [JN] Parallel feed helps power output?
Date: Sat, 25 Mar 2000 07:55:53 +1100
Source: Sound Digest Archive v02.n494
Gordon,
| >Yes, I am using John Camille's C$s source as a plate load.
You wrote:
| Can someone tell me why this rejects noise from the power supply? It is
| active...
|
| I have always gotten better results from a choke.
I have conducted tests with current sources, thinking they stopped power
supply noise dead in its tracks, but have been very disappointed. To
achieve a reasonable PSRR, but still nothing like a properly dimensioned
choke as Gordon remarks, you must decouple the current source with an RC.
Even then I'd estimate that better than 40% of the PSRR then comes from the
decoupling, not the CCS. What is worse is that the peturbations which get
through a CCS are particularly audible.
It really surprised me. A lot of hash gets through a CCS - believe it - and
it is quite audible when you decouple the supply. I think it relates to
differences in dynamic impedances between the base and emitter circuits -
these differences generate small voltages which are amplified by the pass
transistor in common emitter - the archetype voltage amplifier - and appear
on the collector output.
I performed these experiments with SS circuits. Doubtless with tubes the
differences would be greater again.
Cheers,
Hugh R. Dean
Melbourne, Australia
=========================================================================
From: David Home <DHome@creo.com>
Subject: RE: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 15:21:20 -0800
Source: Sound Digest Archive v02.n495
Hi Gordon. I don't understand your objection. If the tube I am loading has a
grid bias of 3V lets say and a gain of 30, then the maximum voltage on the
plate will rise 90V at the peak above the voltage on the plate at steady
state. So if I set my CCS to drop 120V across it, then there is always 30V
of room before the CCS goes nuts. Is this a mistaken understanding of what
is going on?
Regards, DAvid
-----Original Message-----
From: J. Gordon Rankin [mailto:waudio@cinti.net]
Sent: Friday, March 24, 2000 2:14 PM
To: Hugh R. Dean; Joenet
Subject: Re: [JN] Parallel feed helps power output?
>It really surprised me. A lot of hash gets through a CCS - believe it -
and
>it is quite audible when you decouple the supply. I think it relates to
>differences in dynamic impedances between the base and emitter circuits -
>these differences generate small voltages which are amplified by the pass
>transistor in common emitter - the archetype voltage amplifier - and appear
>on the collector output.
Hugh,
I really do not see the rejection also. To me an active device is only
going to multiply the problem, not reect it.
Also I have taken a look at several of these circuits and find that
people are not accounting for the MAX gain of the tube it is loading. At
the MAX gain the CCS is actually failing to provide any load.
Listen guys, loose the SS crap and spend 10 bucks more on a good 100H
choke.
Gordon
=====> Wavelength Audio <=====
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: dslagle@earthlink.net (dave slagle)
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 16:27:03 -0500
Source: Sound Digest Archive v02.n495
>Simple the only good bi-amp system is with two of the exact same
>amplifiers. This is the only way you can secure the same sonic signature
>(was one of my senior projects). At that point what's the point.
ok... thats your opinion...
if we must have the same sonic signature... build the same exact amps with
the same everything including cores for the output... only wind one with
inductance being the goal, and optimise the other for winding
capacitences... i would think the signature would be similar.
>I still say, low watt plus subs under 100Hz is the best. Not perfect but
>pretty close.
do you still use a full bandwith down to 20hz output trannie? or would one
that only goes to 40hz suffice? that extra 20hz reqires twice the winding
inductance... which you pay for somewhere else.
dave
=========================================================================
From: "Dave Aukerman" <aukdav@wcoil.com>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 21:15:06 -0500
Source: Sound Digest Archive v02.n495
Prove it.
Sounds like another way of getting a bit more $$ for the extra junk in the
signal path. And yes . . . it is in the signal path.
Dave
=========================================================================
From: "P. de R. L." <triode@bow-tie.org.uk>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 21:33:45 -0000
Source: Sound Digest Archive v02.n495
Large tranny = large leakage I suspect; try a toroid??
Paul
- ----- Original Message -----
From: James Melhuish <james@melhuish.org>
To: Joelist <sound@lists.io.com>
Sent: Thursday, March 23, 2000 11:54 PM
Subject: Re: [JN] Parallel feed helps power output?
> Would making the normal SE transformer exceptionally large and expensive
> reduce the possibility of saturation and improve bass performance.
> After all, if we are paying for two (plate choke and output
> transformer), why not pay for one super transformer?
>
> James
> --
> James Melhuish
> mailto:james@melhuish.org
> http://melhuish.org
>
=========================================================================
From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 21:49:05 +0300
Source: Sound Digest Archive v02.n495
"J. Gordon Rankin" wrote:
> Gang,
>
> Just want to clear up a few things:
>
> 1) Many suggest that the PF lowers the noise floor because of the large
> loading choke. I would tend to disagree with this statement because most
> of the noise is coming from the input stage in either PF or DF (Direct
> Feed).
I agree with you , Gordon.
The PSU supplying the output stage is VERY simple indeed to make noise
free.
If any audible noise is damped by the PF , it certainly need a few more
L's
or C's , or better grounding path.
Anyway , it will show up as modulations upon the audio signal , so only
common sense thing is to improve the PSU.
NO PSU should ever be able to influence the output stage with noise.
>
>
> 2) The cap before or the cap after (i.e. Plate or Ground). Don't ask me
> why because in all engineering experience there should not be a
> diference.
Oh no. There is a engineering difference if the windings does not have
the same potential. It had been mention here several
times during the past two days , so I wont repeat it.
But grounding of both the primare and secondary , with the cap bewteen
anode and transformer , I trust is the best solution.
Further it would also be a very safe method.
> 3) Cap size... Man this is a hard one, but in deeveloping the Mercury
> amps I spent a lot of time fooling with size. I found the lower the value
> (without drastic phase problems in the bass) made the cap type less
> influential. I typically use high inductance low capacitence and this
> works for me.
100% agreed. Still the cap needs to transfer as low as possible , in my
opinion.
I would tend to get as close to 2 Hz/- 3 dB , as I can , without being
fanatic about it.
But it will conflict with the cathode bypass cap , if such is used.
I will avoid the cathode cap , at any price , just to simplify the
circuit ,
and replace it with active bias.
I can certainly do with the tube, choke , cap and OPT referring to the
same
stage. No need to complicate this mess further , as I see it.
- - Kurt.
=========================================================================
From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 22:17:13 +0300
Source: Sound Digest Archive v02.n495
Phil Sieg wrote:
>
> >>We have a tube parallel with a choke and a OPT in series with a cap.
> >>On top on that , is as you say the cap between the windings.
> >>This is INDEED a VERY complicated circuit as all is out of common phase.
>
> Which is another reason to hang it off the ground leg of the OPT primary.
Well , I can see no objection about grounding BOTH windings.
Then the cap will do best on top of the transformer.
> >>I am pretty sure it will be an advantage to place the signal cap between
> ground and OPT primary winding.
> >>However if the secondary is grounded , I am having difficult in spotting
> the best approach.
>
> Secondary is not grounded, however. There's no DC in there anymore son I
> can't see the need to ground the secondary.
Never has been. I am not sure I follow you here ?
The reason for grounding it is to remove the electrostatic Voltage field , and
control the capacitance.
If you watch a 10-20 kHz square , you will see the difference.
It is also important to connect the outer primary winding to B+.
These false signals are unaffected upon transformer screening , however a
screened ( potted ) OPT , will not transmit these signal to the surrounding
electronics.
If you do not have the tools to perform this test , you can A/B test it on , say
an "open" Opera or other acoustic recording.
( Choirs with lots of high voices , or if your system is good with the
perspective )
It is harder to hear the effect on a rock band.
> >>A consideration with cap choices when contemplating PF, is that the AC
> signal from the plate goes through the coupling cap, the primary winding of
> the output transformer and then can be returned directly back to the output
> tube cathode. Notice that the cathode resistor bypass cap is now out of the
> signal path? Some guys don't even bother with a cathode bypass cap at all<<
>
> >>Woo. I am not sure I agree here though.
> >>Adding just another signal path ( Time constant ) to the already much to
> many , gives me the creep.
> >>( Anyway it is still in the signal path )
>
> I think it can work at the line stage level where there is no cathode bypass
> cap. I'll let you know beccause I'm going to try it on the preamp I'm
> currently building. If it screws things up, back to ground with the
> parafeed cap.
Yes , but the signals are so complicated here , that even changing a certain
component for an improvement or worse situation in your stage , can not be used
as an conclusion for another circuit.
I have this "blind faith" in simplifying. 95 out of 100 times , simple is better
, according to my experience.
I will drive the stage with a CF , and letting this bias the stage. I simply
LOVE the sound of these method.
I know it is considered bad practice , here on Joelist , but I have to trust my
own ears.
At least it works in my circuits , according to my ears , and the ones I play it
for.
And at the same time , I remove TWO caps from the circuit , improves the
frequency , pulse and phase response , by a quite high factor.
- - Kurt
=========================================================================
From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 22:25:40 +0300
Source: Sound Digest Archive v02.n495
James Melhuish wrote:
> Would making the normal SE transformer exceptionally large and expensive
> reduce the possibility of saturation and improve bass performance.
> After all, if we are paying for two (plate choke and output
> transformer), why not pay for one super transformer?
No , I am not worried about big transformers.
But in my 212 circuit , I intent to use the F-2012 PP transformer. This can
actually supply down to 2 Hz , and 5 Hz clean.
( I cant remember at what power , though )
Building such an animal for SE , with full idle from the 212 , and isolation
at several kV , will make in in my weight class , and not very expensive ,
but SUPER expensive.
And I am pretty sure that the high frequency response would not be
better.....
But if anyone would offer me an opportunity to try such a monster , I would
say YES ;-)
- - Kurt
=========================================================================
From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 2000 23:45:41 +0300
Source: Sound Digest Archive v02.n495
John Levreault wrote:
> Kurt Steffensen wrote:
> >
> > Oh , another thing. Someone earlier claimed that the parafeed circuit
> > influenced the previous stages.
> > I do think that this is a wild goose. It does not change the stages
> > previous to it more than any other circuits.
> > It might if pushed into grid current act a little different to the
> > driver than the conventional circuit , but that is it.
> > But maybe it was meant in another way.
>
> There is a subtle but easily measurable effect on previous stages when
> using a parafeed output: Less of the output signal shows up on the power
> supply.
Only if the isolation and regulation is not good enough.
None of my circuits affect one another through the PSU , in the contend that
it is possible to measure. Not even during high pulses , into clipping.
According to my imagination ground and B+ is AC wise the same current path..
That's why the involved components are indeed parallel at AC.
Do you not agree here , John ?
- - Kurt
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 00 17:14:06 -0500
Source: Sound Digest Archive v02.n495
>It really surprised me. A lot of hash gets through a CCS - believe it - and
>it is quite audible when you decouple the supply. I think it relates to
>differences in dynamic impedances between the base and emitter circuits -
>these differences generate small voltages which are amplified by the pass
>transistor in common emitter - the archetype voltage amplifier - and appear
>on the collector output.
Hugh,
I really do not see the rejection also. To me an active device is only
going to multiply the problem, not reect it.
Also I have taken a look at several of these circuits and find that
people are not accounting for the MAX gain of the tube it is loading. At
the MAX gain the CCS is actually failing to provide any load.
Listen guys, loose the SS crap and spend 10 bucks more on a good 100H
choke.
Gordon
=====> Wavelength Audio <=====
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: "J. Gordon Rankin" <waudio@cinti.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Fri, 24 Mar 00 17:14:07 -0500
Source: Sound Digest Archive v02.n495
Dave,
>if we must have the same sonic signature... build the same exact amps with
>the same everything including cores for the output... only wind one with
>inductance being the goal, and optimise the other for winding
>capacitences... i would think the signature would be similar.
Wouldn't it be simpler just to make a one amp system?
>>I still say, low watt plus subs under 100Hz is the best. Not perfect but
>>pretty close.
>
>do you still use a full bandwith down to 20hz output trannie? or would one
>that only goes to 40hz suffice? that extra 20hz reqires twice the winding
>inductance... which you pay for somewhere else.
I still make the amps to LESS than 20Hz... Figure the bandwith will still
overlap at that point anyway.
Gordon
=====> Wavelength Audio <=====
mailto:waudio@cinti.net
http://www.WavelengthAudio.com
ph.fx. 513-271-4186 USA
=========================================================================
From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
Subject: Re: [JN] Parallel feed helps power output?
Date: Sat, 25 Mar 2000 00:04:32 +0300
Source: Sound Digest Archive v02.n495
tube@jump.net wrote:
This one bothered me for a year or so, because what everyone says is
> true; the same current goes thru the cap regardless of its position.
> Since it sounds better if the cap is grounded regardless of theory,
> something MUST be happening that the theory is missing. The only thing
> I have come up with is this: When the cap is grounded, it doesn't
> "move" much in an electrostatic sense. Especially if the outer foil is
> grounded, the cap is effectively shielded from stray electromagnetic
> fields. If, however, the cap is between the tube and the transformer,
> it is moving up and down literally hundreds of volts at extremely high
> speed. In effect, it is "exposed".
True. It is in a way almost floating when the AC moves. Most certainly the
secondary winding is , if it is not returned to B+ or ground.
I would not like to return this to B+ , from obvious reasons , so the natural
thing would be to ground it.
> We can test this by simply shielding the cap, preferably with a foil
> that shields both electrostatic AND magnetic fields. If it sounds a lot
> better with the shield, we're on to something! And no I still don't
> have my own amp, so I haven't tested it, but ... Michael Percy sells
> some "TI foil" that should do the trick. It might even be helpful to
> elevate the cap away from any dielectrics, like PC boards.
Hmm. Yes , that is actually true. The cap is nervous as well. :-)
> Notice also that if this is true (that shielding improves the sound),
> that this would also apply to interstage coupling caps
Oh , it does effect the performance. Just how much depends upon cap , circuit
and placement.
For instance in my regulated PSU the only cap , ( In the error amplifier ) ,
changes the performance and noise rejection by several dB's ,
just by polarizing it proper. ( Depends upon the circuit , but is usually outer
to ground or B+ , or in the case of potted caps , the screen )
> . Perhaps this is
> one reason that interstage transformers tend to sound better than caps.
Hmm. ;-)
But never mind all the speculation.
As I see it we only need to ground the two OPT windings , and all our worries
are over.
This means that the cap has to be between the anode and the OPT.
If we consider the eventually electrostatic effects of this cap to still be a
problem , we could pot it , and return this to ground as well.
This would be like wearing both belt and braces.
And also regarding the difficulties with the cathode bypass cap.
Why not simply get rid of it , ad a little resistance to defend the fewer
remaining problems to a degree.
We can still bias the output tube at the grid , without messing with the phase
related problems in any way.
We do want ANY signal dependant oscillation , do we ? ;-)
Nice to hear a little from the good head of yours again , Phil.
I think I agree with you all the way. But I guess in electronics it is better
to avoid problems than , seeking them.
At least it is the way I see it , in this PF matter.
My modest bid is: ground the transformer windings , and dump the cathode
electrolytic.
- - Kurt.
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Sat, 25 Mar 2000 09:21:20 -0500
Source: Sound Digest Archive v02.n495
Kurt Steffensen wrote:
>
>
> Oh no. There is a engineering difference if the windings does not have
> the same potential. It had been mention here several
> times during the past two days , so I wont repeat it.
> But grounding of both the primare and secondary , with the cap bewteen
> anode and transformer , I trust is the best solution.
> Further it would also be a very safe method.
I'm not sure I agree. I recall many years ago reading an article which
showed that the distortion of a capacitor was reduced if there was a
polarizing voltage across the cap. Also, some people wrap foils
connected to batteries around components and claim that they sound
better. I'm sure there are other phenomena at work here, but if the
mechanism that effects the sound of the parafeed transformer is the
primary-to-secondary capacitance, then polarizing it (by placing the cap
in the "ground" leg of the primary) may be preferred.
As for safety, any transformer that can't handle 5-600V from primary to
secondary shouldn't be on the market. You can always float your
secondary anyway, which sounds better to my ears.
JL
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Sat, 25 Mar 2000 09:48:37 -0500
Source: Sound Digest Archive v02.n495
Kurt Steffensen wrote:
>
> John Levreault wrote:
>
> > There is a subtle but easily measurable effect on previous stages when
> > using a parafeed output: Less of the output signal shows up on the power
> > supply.
>
> Only if the isolation and regulation is not good enough.
> None of my circuits affect one another through the PSU , in the contend that
> it is possible to measure. Not even during high pulses , into clipping.
>
> According to my imagination ground and B+ is AC wise the same current path..
> That's why the involved components are indeed parallel at AC.
> Do you not agree here , John ?
Yes, of course, on a qualitative basis. But I don't know anything about
your power supplies, so it is impossible for me to comment about them
specifically, although your claim that "none of my circuits affect one
another through the PSU" suggests to me that you're not looking close
enough! ;-) Some people like to use heavy regulation, and that would
help a lot, but I dislike the sonics of regulators, but that's just my
opinion. However, all regulators run out of feedback at some point.
Dealing with these effects passively with either lots of capacitance or
parallel combinations of caps with staggered values has its own sonic
problems. My own experimenation suggests that a small _but finite_ power
supply impedance may be the best sonically, but it does allow a certain
amount of this signal propagation.
And I'm not necessarily saying that this signal propagation is a bad
thing. I am reminded of Bob Danielak's claim that running all stages
from a common power supply connection (i.e. no R-C or L-C from stage to
stage) has good sonics. I agree, and it may be simply that such a
connection does not "smear" those signals that do manage to find their
way back to the supply.
JL
=========================================================================
From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
Subject: Re: [JN] Parallel feed helps power output?
Date: Sat, 25 Mar 2000 20:45:57 +0300
Source: Sound Digest Archive v02.n496
Dear John , - Joes.
John Levreault wrote:
> I'm not sure I agree. I recall many years ago reading an article which
> showed that the distortion of a capacitor was reduced if there was a
> polarizing voltage across the cap.
Yes , that's another side of the same story , and why I suggest to ground
it.
These un polarized capacitors can be found in circuits such as speaker
x-overs. In valve amplifiers they are always polarized.
I If the secondary winding is grounded or otherwise returned to a well
defined Voltage.
But in this particular PF design , it is not. That's why the grounding will
polarize it.
In fact it is short circuited to ground. I am pretty sure it wont do anymore
harm by this solution ;-)
> Also, some people wrap foils
> connected to batteries around components and claim that they sound
> better.
Yes , but I do not know anything about that.
I sometimes wrap copper foils around selected components , and ground these
, if that is a similar method ?.
> I'm sure there are other phenomena at work here, but if the
> mechanism that effects the sound of the parafeed transformer is the
> primary-to-secondary capacitance, then polarizing it (by placing the cap
> in the "ground" leg of the primary) may be preferred.
But that will not polarize it ?
Why not simply ground both windings , and withdraw that unwanted capacitor ?
> As for safety, any transformer that can't handle 5-600V from primary to
> secondary shouldn't be on the market.
No , no ofcourse. I only mentioned it as another win with the approach. I
hope that no one minds that little extra safety.
In the 212 circuit , I mentioned , the transients runs up to several kVolts.
Imagine how the secondary will run up and down in the opposite direction as
mad.
You can actually see that on the oscilloscope , and hear it on the audio
signal.
( I do not mean by connecting the probe between the windings , as will will
more or less cancel the mechanism , but actually seeing it , at the output
signal
with squares or other pulse alike signals )
> You can always float your
> secondary anyway, which sounds better to my ears.
Well , not to mine. Again by floating it we have this "nervous"
electrostatic effect between the windings. This is the same as you refer to
with the unpolarized
capacitor.
> According to my imagination ground and B+ is AC wise the same current
path..
> That's why the involved components are indeed parallel at AC.
> Do you not agree here , John ?
>Yes, of course, on a qualitative basis. But I don't know anything about
>your power supplies, so it is impossible for me to comment about them
>specifically, although your claim that "none of my circuits affect one
>another through the PSU" suggests to me that you're not looking close
>enough! ;-)
It does not have to be my PSU's. It goes for all PSU's.
And regarding good regulation , then think of it as every stage has its
entirely own PSU.
My point was that the parafeed circuit does not affect the previous stages
at all. And if it does it is through the PSU.
The cure would not be to implant PF in the output stage , or any other
stage, in order to prevent this effect , but simply to build a better PSU.
I am sure no one will disagree with that viewpoint.
>Some people like to use heavy regulation, and that would
>help a lot, but I dislike the sonics of regulators, but that's just my
>opinion.
All right. But regulators are such a wide issue. I can not understand why
you will abound them all.
But I fully accept your viewpoint , John.
>However, all regulators run out of feedback at some point.
I do not know what you mean by that.
A good designer would not allow that to happen , if I understand you right ?
>Dealing with these effects passively with either lots of capacitance or
>parallel combinations of caps with staggered values has its own sonic
>problems. My own experimenation suggests that a small _but finite_ power
>supply impedance may be the best sonically, but it does allow a certain
>amount of this signal propagation.
That's allright with me that you see it this way. But I really can not see
anything bad about high and good isolation/regulation.
>And I'm not necessarily saying that this signal propagation is a bad
>thing. I am reminded of Bob Danielak's claim that running all stages
>from a common power supply connection (i.e. no R-C or L-C from stage to
>stage) has good sonics. I agree, and it may be simply that such a
>connection does not "smear" those signals that do manage to find their
>way back to the supply.
Do I misunderstand you , John. ?
I commented on your post where you considered that the PF improved the
previous stages , due to poor regulation.
Now it almost sound like if you prefer this modulation ;-)
I am sure you know that really poor regulation of the PSU will allow the
amplifier to oscillate as mad.
When the regulation is a little better , this will be under control in
steady conditions , but it will still oscillate at certain very low
frequencies.
When these are up in the audio range , they are referred to as "motor
boating".
If the PSU is further improved , it will only oscillate at certain signal
levels and/or frequencies.
Further improvement will decrease the THD. ( In fact these are still signal
dependant oscillations )
At zero Z-out DC to say 200 kHz , the PSU will be perfect , not matter what
we do to it.
We still do not have such good batteries or electrolytics , but a good care
full designed regulated PSU , will bring us very close to that goal.
Thanks for your nice reply , John.
I hope you make it to the summer triode festival up here in Denmark.
- - Kurt
=========================================================================
From: "Dave Slagle" <dslagle@earthlink.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Sat, 25 Mar 2000 23:28:52 -0500
Source: Sound Digest Archive v02.n496
>
> Listen guys, loose the SS crap and spend 10 bucks more on a good 100H
> choke.
>
scary thing is... last time i checked... there were 100hy plate chokes for
tubes like a sn7 available for far less than any ccs will cost you....
i seem to remember $50 or so a pop... they are open channel a frames and
ugly... but they do the job...and when you think of it... they are much
prettier in their open frames than any ccs on a perf board.... hell the
simplicity of an "a" channel choke would make me proud to display it, while
a sand-board up top would only impress the wrong people...
furthermore... i always wonder what the need is to re-invent the wheel...
when proper use of the original wheel has yet to be realized... seems like
many of us don't even know what we are trying to better...
following the whole PS interaction thing... i'll side with danielak jl and
others who dare to say.. a shared supply or gasp cathode resistor may
actually be more musical...
dave
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] Parallel feed helps power output?
Date: Sun, 26 Mar 2000 10:39:06 -0500
Source: Sound Digest Archive v02.n496
Kurt Steffensen wrote:
>
> John Levreault wrote:
>
> > >However, all regulators run out of feedback at some point.
>
> I do not know what you mean by that.
> A good designer would not allow that to happen , if I understand you right ?
What I meant was that, since a voltage regulator requires feedback, it's
subject to the same rules as opamps and feedback-type power amps.
Therefore, you cannot have infinite amounts of negative feedback without
also having stability problems. It's not unusual for the amount of
negative feedback to fall to relatively low levels somewhere in the
audio range. As the feedback falls, the output impedance goes up. You
can patch this up with capacitors, but they add their own sonic
signature.
>
> >Dealing with these effects passively with either lots of capacitance or
> >parallel combinations of caps with staggered values has its own sonic
> >problems. My own experimenation suggests that a small _but finite_ power
> >supply impedance may be the best sonically, but it does allow a certain
> >amount of this signal propagation.
>
> That's allright with me that you see it this way. But I really can not see
> anything bad about high and good isolation/regulation.
This may be a case where the cure is worse than the disease, though!
>
> >And I'm not necessarily saying that this signal propagation is a bad
> >thing. I am reminded of Bob Danielak's claim that running all stages
> >from a common power supply connection (i.e. no R-C or L-C from stage to
> >stage) has good sonics. I agree, and it may be simply that such a
> >connection does not "smear" those signals that do manage to find their
> >way back to the supply.
>
> Do I misunderstand you , John. ?
> I commented on your post where you considered that the PF improved the
> previous stages , due to poor regulation.
> Now it almost sound like if you prefer this modulation ;-)
If an output tube and a driver share a common power supply node with a
finite impedance, some of the amplifier tube's output will propagate
back to the driver stage. However, that signal does not experience any
phase shift, so it's a linear term that simply modulates the gain of the
driver to a very small degree. (If this signal gets too large,
motorboating will occur.) So what I'm saying is that it depends on
what's going on between the stages. You recommend the use of a regulator
with very low output impedance, some use passive psu filters with lots
of capacitance to isolate stages, while others tie stages to a common
point. The bottom line is that any of these techniques can be successful
in thwarting psu-induced intermodulation. However, and here's the key,
they each have different sonic impact.
>
> I am sure you know that really poor regulation of the PSU will allow the
> amplifier to oscillate as mad.
> When the regulation is a little better , this will be under control in
> steady conditions , but it will still oscillate at certain very low
> frequencies.
> When these are up in the audio range , they are referred to as "motor
> boating".
You're absolutely correct. But it really doesn't take all that much
filter capacitance to keep a low-powered tube amp from motorboating,
although I don't use 212's! Again, we're both talking about the same
thing, but it's how we each accept the sonic compromises in our favorite
technique that makes us different. And that's what makes this stuff fun!
JL
=========================================================================
From: Rick Francis <rfrancis@glasscity.net>
Subject: [JN] Parallel MV rects WAS bridge gives lower impedance???
Date: Thu, 09 Dec 1999 10:09:40 -0500
Source: Sound Digest Archive v02.n358
At 08:45 AM 12/9/99 -0500, dave slagle wrote:
>
>>The tubes are lo-Z, but what about those mandatory plate resistors?
>
>what mandatory plate resistors... i would never put anything resistive
>anywhere near a powersupply.
>
To use merc vapor rectifiers in parallel, one must use series resistors.
Otherwise one will carry the whole load.
But what happens in a FW BRIDGE? Would only two of the tubes be conducting
at any time if no resistors were used?
Rick
=========================================================================
From: "Verhoeff, A..A." <verhoeff@awvn.nl>
Subject: [JN] Parallel PP with tetrode 6V6-GT
Date: Sun, 2 Sep 2001 08:59:26 +0200
Source: Sound Digest Archive v02.n959
Hello Joes,
The French magazine Led published in a recent issue a parallel push pull
design with the tetrode 6V6-GT.
This magazine seems to permutate over the years all sorts of DIY-designs
tube topologies and could be categorised as 'le petite audiophile' (in
comparison to the former famous French magazine L'Audiophile). The article
draws the conclusion that the design is way better than a comparable design
with the EL84. Also the precision, neutrality and especially the dynamics
get very close to their SE-no feedback design with an 845. One of the
learning points they describe is that a parallel design does have
disadvantages, but it improves the competence in dynamics of an amplifier.
Their finding could be true for PP-designs, does it also apply on
SE-designs?
Any opinions?
Best regards, Arjen
======================================================================
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=========================================================================
From: TubeGarden@aol.com
Subject: Re: [JN] Parallel PP with tetrode 6V6-GT
Date: Sun, 2 Sep 2001 09:11:44 EDT
Source: Sound Digest Archive v02.n959
- --part1_75.1a78f6fc.28c38a10_boundary
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
In a message dated 9/2/01 12:02:10 AM US Mountain Standard Time,
verhoeff@awvn.nl writes:
> parallel design does have
> disadvantages, but it improves the competence in dynamics of an amplifier.
> Their finding could be true for PP-designs, does it also apply on
> SE-designs?
>
Greets!
John Atwood amps show good sound with SE parallel EL34.
www.one-electron.com
Happy Ears!
Al B^}
- --part1_75.1a78f6fc.28c38a10_boundary
Content-Type: text/html; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
<HTML><FONT FACE=arial,helvetica><BODY BGCOLOR="#ffffff"><FONT SIZE=2>In a message dated 9/2/01 12:
02:10 AM US Mountain Standard Time,
<BR>verhoeff@awvn.nl writes:
<BR>
<BR>
<BR><BLOCKQUOTE TYPE=CITE style="BORDER-LEFT: #0000ff 2px solid; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px
; PADDING-LEFT: 5px">parallel design does have
<BR>disadvantages, but it improves the competence in dynamics of an amplifier.
<BR>Their finding could be true for PP-designs, does it also apply on
<BR>SE-designs?
<BR></FONT><FONT COLOR="#000000" SIZE=3 FAMILY="SANSSERIF" FACE="Arial" LANG="0"></BLOCKQUOTE>
<BR></FONT><FONT COLOR="#000000" SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0">
<BR>Greets!
<BR>
<BR>John Atwood amps show good sound with SE parallel EL34.
<BR>
<BR>www.one-electron.com
<BR>
<BR>Happy Ears!
<BR>Al B^}
<BR>
<BR></FONT></HTML>
- --part1_75.1a78f6fc.28c38a10_boundary--
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] Parallel PP with tetrode 6V6-GT
Date: Sun, 02 Sep 2001 17:51:08 +0200
Source: Sound Digest Archive v02.n959
dear Arjen,
It has been my experience that parallelling low impedance devices is a
difficult task 9it works but transparanecy gets lost)
The above holds for triodes, not for penthodes (as these are tens of k-ohms)
best regards
- -
Guido
At 08:59 2-9-01 +0200, Verhoeff, A..A. wrote:
>Hello Joes,
>
>The French magazine Led published in a recent issue a parallel push pull
>design with the tetrode 6V6-GT.
>This magazine seems to permutate over the years all sorts of DIY-designs
>tube topologies and could be categorised as 'le petite audiophile' (in
>comparison to the former famous French magazine L'Audiophile). The article
>draws the conclusion that the design is way better than a comparable design
>with the EL84. Also the precision, neutrality and especially the dynamics
>get very close to their SE-no feedback design with an 845. One of the
>learning points they describe is that a parallel design does have
>disadvantages, but it improves the competence in dynamics of an amplifier.
>Their finding could be true for PP-designs, does it also apply on
>SE-designs?
>
>Any opinions?
>
>Best regards, Arjen
>
>
>
>======================================================================
>E-MAIL DISCLAIMER: http://www.awvn.nl/disclaimer.htm
>Of ontvang de disclaimer door een leeg e-mailbericht te sturen aan:
>Or receive the disclaimer by sending a blank e-mail message to:
>mailto:disclaimer@awvn.nl
>======================================================================
=========================================================================
From: Eric Kingsbury <ekingsbu@hawaii.edu>
Subject: Re: [JN] Parallel PP with tetrode 6V6-GT
Date: Tue, 04 Sep 2001 19:51:10 -1000 (HST)
Source: Sound Digest Archive v02.n960
On Sat, 1 Sep 2001, Verhoeff, A..A. wrote:
>
> The French magazine Led published in a recent issue a parallel push pull
> design with the tetrode 6V6-GT.
The article
> draws the conclusion that the design is way better than a comparable design
> with the EL84. Also the precision, neutrality and especially the dynamics
I've been listening to a PP (triode) 6V6 amp for quite a while now; have
hardly heard anything to substantially better it. I think it's a secret
gem. Very high rez, nice sweet, neutral sound, high color (of
instruments).
Go have a look.
http://ekingsbu.users4.50megs.com/blurb1.html
Poinz
=========================================================================
From: Jeremy Epstein <jepstein@shwd.com>
Subject: [JN] Parallel Single-Ended Darling Schematic Online
Date: Mon, 05 Apr 1999 08:54:38 -0400
Source: Sound Digest Archive v02.n109
For those of you who'd like to see the circuit Bob and I (mostly Bob!)
developed for the parallel single-ended Darling amp, it is here :
http://www.enjoythemusic.com/nynoise/epstein.gif
(Thanks to Steve Rochlin for the hosting!)
Note the built-in 88Hz roll-off to accomodate a subwoofer in my system :
us a larger coupling cap (.2uF would be plenty large enough I guess) for
full-range operation. Also note I use a 6SN7 driver and this gives me
less overall gain than the stock Darling circuit.
Before anyone asks, yes, I know the 8K:8 ohm output load is not what one
might expect from theory. It's a long story. I am currently
experimenting with different loads and I will report back when I've
drawn a conclusion. And I also know that the cathode bypass caps are way
too big all around but that's what Radio Shack carries. Go try some
Black Gates and tell me how they sound! I might go for some spendies
eventually but right now I'm sticking with the Radio Shack (Nichicon)
parts. They measure well in the low-$ spec.
- -j
- --
=====================================
Jeremy Epstein .... jepstein@shwd.com
=====================================
=========================================================================
From: RALPH POWER <POWER.RALPH@epamail.epa.gov>
Subject: [JN] Parallel Single-Ended Darling Schematic Online -Reply
Date: Thu, 08 Apr 1999 15:50:02 -0400
Source: Sound Digest Archive v02.n114
Hi Jeremy,
You said :
>And I also know that the cathode bypass caps are way
>too big all around but that's what Radio Shack carries. Go try some
>Black Gates and tell me how they sound! I might go for some spendies
>eventually but right now I'm sticking with the Radio Shack (Nichicon)
>parts. They measure well in the low-$ spec.
Wow, I didn't know that Radio Shack lytics were Nichicons. That's great
since I own stock in Radio Shack... ; > )
Recently I have come to really appreciate Nichicon caps and especially their
top-of-the-line Muse series (KZ and FA types especially). Still very cheap
versus Black Gates at 50 cents to $2 each.
I have just finished swapping out cathode bypass caps in my amps and am
delighted with the sound of the Nichicons versus Black Gates, Rubycons
and others. They are very neutral with a slightly warm balance with great
bass and no loss of resolution, just not hyped.
Standard Rubycons, from Mouser, were a little veiled on top versus BGs or
Nichicons on input tubes, might be OK for output tubes however.
Black Gate caps are extremely detailed and can cause the sound to become
too "top heavy" or "tizzy" if used on both input and output tubes, or at the
wrong place in an amp.
I have found that I can "voice" the sound of my amps, correct frequency tilts,
and improve resolution just by mixing and matching cap brands for cathode
bypass on input and output stages. Their impact on sound quality is quite
shocking.
In my amps, Black Gates are better utilized on the input tubes of my SE amps
than on the output tubes themselves. I even replaced a $30 nonpolarized BG
(NX), with a $1.50 Nichicon KZ on my SE 6B4G and the amp improved remarkably
in balance and clarity. The BG Nonpolarized cap remains on the input 5842.
I replaced the BG cathode bypass caps from my PP 6B4G amp with Nichicon
FAs on the 5842s and KZs on the 6B4Gs, which warmed up the sound and
eliminated a slight tizzyness. I also tried running without cathode bypass caps on
the 6B4Gs, but I swear I could hear the sound "squash" without them. The sound
is now balanced very close to that of the SE 6B4G and much more musical than
before.
I have also had good luck using 22uf Solens as cathode bypass caps on 45s
and 71A output tubes. Here they let through excellent detail but in a most natural
way, and not at all "plastic" sounding. I used a Black Gate as input (5842) cathode
bypass on the 71A instead of the Nichicon as it needed a little more top end boost.
I guess I'm just amazed what a difference cathode bypass caps can make in the
overall musicality of an amp. It's like cooking, a dash of detail here or a pinch of
warmth there. Balance is EVERYTHING !
Got a problem with the sound of your amp ? Try different cathode bypass caps.
Having more fun,
- Ralph
=========================================================================
From: "Multi-Volti Devices" <multi-volti@softhouse.com>
Subject: [JN] parallel SS and vacuum diodes
Date: Tue, 1 Jun 1999 01:36:55 -0400
Source: Sound Digest Archive v02.n160
That's interesting...I wonder what exactly the vacuum diodes do when their
forward voltage is clamped to a solid state forward junction drop when
forward biased. Reverse biased, I imagine both are 'cut off', with whatever
secondary effects would also be present.
Anyone able to comment with an explanation? I realize there is probably no
textbook explanation for this configuration...there isn't a 'conventional'
reason to use them this way.
Thanks
Murray
=========================================================================
From: Ken Gilbert <ride5000@ride.ri.net>
Subject: [JN] parallel SS and vacuum diodes
Date: Wed, 02 Jun 1999 17:40:07 -0400
Source: Sound Digest Archive v02.n164
>That's interesting...I wonder what exactly the vacuum diodes do when their
>forward voltage is clamped to a solid state forward junction drop when
>forward biased. Reverse biased, I imagine both are 'cut off', with whatever
>secondary effects would also be present.
Hmmm... interesting thought. I have nothing other than my common-sensical
mind to sort this out, but IIRC one of the biggest problems with the SS
diodes is the hard turnon-turnoff characteristic. The tube diode displays
none of these annoying characteristics, so perhaps when conducting (as soon
as the SS diodes clamp off, for example) they offer a less drastic dI/dT,
therefore the system as a whole is quieter.
~KG~
=========================================================================
From: dslagle@earthlink.net (dave slagle)
Subject: RE: [JN] Parallel Triode
Date: Thu, 25 Jan 2001 07:49:24 -0500
Source: Sound Digest Archive v02.n792
>Same gain but effectively double gm and half ra. i.e. more drive, lower
>output impedance.
>
>So, better handles possible grid current on peaks and gives wider bandwidth
>as a lower value grid resistor (load) is possible to avoid roll off due to
>Mr Miller.
also twice as difficult to drive... so be aware of the preceeding stage,
grid resistor etc.
i always hear of the bluured sound with paralleled triodes... but i have
never seen people double the drive when they double the tube... i wonder if
thats whats blurring the sound?
dave
=========================================================================
From: Andry Gunawan Satyaputra <agsatyaputra@aitbatam.com>
Subject: [JN] Parallel Triode
Date: Thu, 25 Jan 2001 09:01:41 +0700
Source: Sound Digest Archive v02.n792
Hi All,
what's the advantage if use parallel triode in driver stage ?
regards
Andry G
=========================================================================
From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: RE: [JN] Parallel Triode
Date: Thu, 25 Jan 2001 11:24:41 -0500
Source: Sound Digest Archive v02.n792
> ----------
> From: dslagle@earthlink.net[SMTP:dslagle@earthlink.net]
> Sent: Thursday, January 25, 2001 7:49 AM
> To: sound@deliverator.io.com
> Subject: RE: [JN] Parallel Triode
>
>
> also twice as difficult to drive... so be aware of the preceeding stage,
> grid resistor etc.
>
> i always hear of the bluured sound with paralleled triodes... but i have
> never seen people double the drive when they double the tube... i wonder
> if
> thats whats blurring the sound?
>
> dave
>
>
hey, wait a minute...
i *tripled* the drive
when i used *five* parallel output tubes
in my D3.5:
http://www.geocities.com/bobdanielak/darling.html
fwiw, i still prefer the single SE version.
i'd like it to be easy to get the same sound as single SE
- -but with more power-
by simply paralleling output tubes, but this has not been my experience.
even with two tubes in parallel.
you seem to loose something.
also, i'm not exactly convinced that it is the paralleling of tubes.
it may simply be a function of the output power.
i have yet to build a higher power amp that has the same "fun-factor"
as the single SE.
perhaps it is related to my speakers.
they provide enough sound to fill my room at decent volume
even with only 0.7W on tap. and for most listening
they do a great job.
now plug in a PSE, or even a 45 or 2a3 amp, and they
obviously have more authority - due to their extra power,
but the "fun-factor" is not quite so high.
45 and 2a3 fans, do not lynch me, i'm talking 99% versus 100%
difference in "fun-factor".
it seems to me that if you can tolerate an amp that is not capable of
pushing your speakers to the point of noticeable distortion
you are better off than trying to control the level by backing off.
in this case, maybe headroom is not desireable.
just a thought....
bob.d.
=========================================================================
From: Christian Rintelen <christian@rintelen.ch>
Subject: Re: [JN] Parallel Triode
Date: Thu, 25 Jan 2001 14:37:26 +0100
Source: Sound Digest Archive v02.n792
I once had a discussion with Lynn Olson about his preamp design
<http://www.teleport.com/~lynno/preamp.gif> which is push-pull parallel feed
with additional resistors in the plate (following the plate load chokes). I
asked him why and he replied as follows: "A minor secondary benefit is the
presence of the 2K dropping resistor on each side of the 7119 plate circuit,
which will tend to equalize the operating points for each side of the 7119.
When the plates are tied together with a low resistance (such as a transformer
primary) ...
Here comes the interesting part as Lynn continues: "...and the cathodes are
tied together as well, small differences in transconductance can multiply to
large differences in current, with 30% imbalance not being unusual. This is the
downfall of the typical parallel connection, for example. (Matt Kamna
discovered the large differences in parallel-connected triodes as part of
another project in researching parallel SE.)"
Dunno if that helps but it seems like a good explanation for the typical
"paralleled blurred sound" (which BTW I also experienced when paralleling four
6C45 into a Sowter SE15 OPT (driven by an IT-coupled 6C45)...
Christian
dave slagle wrote:
> >Same gain but effectively double gm and half ra. i.e. more drive, lower
> >output impedance.
> >
> >So, better handles possible grid current on peaks and gives wider bandwidth
> >as a lower value grid resistor (load) is possible to avoid roll off due to
> >Mr Miller.
>
> also twice as difficult to drive... so be aware of the preceeding stage,
> grid resistor etc.
>
> i always hear of the bluured sound with paralleled triodes... but i have
> never seen people double the drive when they double the tube... i wonder if
> thats whats blurring the sound?
>
> dave
- --
Konzept und Text: Christian Rintelen
Dufourstrasse 165 - CH-8008 Zurich - Switzerland
Voice: +41 1 420 11 55 - Fax: +41 1 420 11 57
mailto:christian@rintelen.ch
=========================================================================
From: "Bart Shepherd \(Home\)" <bart.s@bigpond.net.au>
Subject: RE: [JN] Parallel Triode
Date: Thu, 25 Jan 2001 20:42:18 +1100
Source: Sound Digest Archive v02.n792
Same gain but effectively double gm and half ra. i.e. more drive, lower
output impedance.
So, better handles possible grid current on peaks and gives wider bandwidth
as a lower value grid resistor (load) is possible to avoid roll off due to
Mr Miller.
Cheers,
Bart
- -----Original Message-----
From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
Behalf Of Andry Gunawan Satyaputra
Sent: Thursday, 25 January 2001 1:02 PM
To: sound@lists.io.com
Subject: [JN] Parallel Triode
Hi All,
what's the advantage if use parallel triode in driver stage ?
regards
Andry G
=========================================================================
From: "Epstein, Jeremy" <JEpstein@ndbcap.com>
Subject: Re: [JN] Parallel Triode
Date: Thu, 25 Jan 2001 13:10:01 -0500
Source: Sound Digest Archive v02.n793
Christian Rintelen wrote:
>>>
Here comes the interesting part as Lynn continues: "...and the cathodes are
tied together as well, small differences in transconductance can multiply to
large differences in current, with 30% imbalance not being unusual. This is
the
downfall of the typical parallel connection, for example. (Matt Kamna
discovered the large differences in parallel-connected triodes as part of
another project in researching parallel SE.)"
<<<
I believe it was Lynn & Matt who published an article last year on the
importance of matching triodes used in parallel, it was in Glass Audio.
I will try this in my tweaked-up Free Lunch Double Darling, which, although
decent, has not been floating my boat all the way to the surface lately. I
wonder what value of series resistor to use?
This is a PSE circuit, with two 1626's connected in parallel to a "Champ"
output transformer of something like 5K:8 ratio.
As a WAG I was going to try 500 ohm R's in series with the plates of each
1626, which are not matched, unless by accident. Anybody have any reason to
try anything different?
- -j
=========================================
Jeremy Epstein........jepstein@ndbcap.com
=========================================
=========================================================================
From: "Epstein, Jeremy" <JEpstein@ndbcap.com>
Subject: RE: Re: [JN] Parallel Triode
Date: Thu, 25 Jan 2001 13:13:14 -0500
Source: Sound Digest Archive v02.n793
Oh, one other thing:
Doesn't using a resistor in series with an inductor make the LF cutoff
extend to a lower frequency? My reasoning is that the reduction of impedance
with frequency plateaus at the resistor (+ DCR of inductor) value. So does
this address half the problem with inductive loading bandwidth?
> As a WAG I was going to try 500 ohm R's in series with the
> plates of each 1626, which are not matched, unless by
> accident. Anybody have any reason to try anything different?
>
> -j
> =========================================
> Jeremy Epstein........jepstein@ndbcap.com
> =========================================
>
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] Parallel Triode
Date: Thu, 25 Jan 2001 19:35:21 +0100
Source: Sound Digest Archive v02.n793
At 09:01 25-1-01 +0700, Andry Gunawan Satyaputra wrote:
>Hi All,
>what's the advantage if use parallel triode in driver stage ?
Lower output impedance, higher transconductance
Disadvantage: Paralleling low impedance devices is a diffcult job, as 2
curves never fit.... (try to connect 2 lab supplies in parallel, that is,
in voltage mode. One always wins, whatever happens.
Now swittch the same supplies in current mode; you'll see no problems
If low output impedance is required it may be better to find another tube /
circuit
Have fun
Guido
>regards
>Andry G
=========================================================================
From: Christian Rintelen <christian@rintelen.ch>
Subject: Re: [JN] Parallel Triode
Date: Thu, 25 Jan 2001 20:39:36 +0100
Source: Sound Digest Archive v02.n793
Right on, Brooklyn (chokes ;-).... Here's what Lynn when I asked him the same
question two years ago: "The resistor between the audio path and the AF chokes
provide a degree of isolation between audio and the small but significant stray
C in the AF choke. This stray C, although small, is not very high quality and
contributes to the "choke" sound. In addition, the resistor prevents the load
from being purely reactive to the plates, and assumes finite values at very
high and very frequencies."
(I understand that Lynn chose not only to deal with the question of what core
material contibutes favourably to the "choke sound", but also which resistor
sounds least obtrusive. No need to laugh, Mr. Slagle!.... ;-)
©
"Epstein, Jeremy" wrote:
> Oh, one other thing:
>
> Doesn't using a resistor in series with an inductor make the LF cutoff
> extend to a lower frequency? My reasoning is that the reduction of impedance
> with frequency plateaus at the resistor (+ DCR of inductor) value. So does
> this address half the problem with inductive loading bandwidth?
>
> > As a WAG I was going to try 500 ohm R's in series with the
> > plates of each 1626, which are not matched, unless by
> > accident. Anybody have any reason to try anything different?
=========================================================================
From: "Epstein, Jeremy" <JEpstein@ndbcap.com>
Subject: RE: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 09:30:30 -0500
Source: Sound Digest Archive v02.n793
Well, I tried this last night, I used 200 ohm resistors in series with the
plates of the 1626's (I had 4 of the 200 ohm parts handy) and it works
pretty well from what I heard in a few short listens last night and this AM.
(My wife wanted me to come up and watch ER with her so last night was cut
short.)
My initial impression is that it helps significantly to focus the sound. I
listened to Mal Waldron & John Coltrane (a mono jazz LP) and I heard a
better focus on Coltrane's horn and a more coherent mono image, centered
better and just a little more unified. Overall I found it to be an
improvement. I heard a distortion on a couple of piano riffs which I need to
find out about - it may be in the record, it may be something I have
introduced, I will listen to some other discs and see what happens.
Note this was in an amp which I (and others) had thought had a problem
exactly with this "smearing" issue, a DC Double Darling. Probably, the
better you match the tubes involved, the less you have to worry about this
but in my case it seems to be a good idea. Anybody have any idea how to
optimize the value of this resistor?
- -j
> -----Original Message-----
> From: Epstein, Jeremy
> Sent: Thursday, January 25, 2001 1:10 PM
> To: 'christian@rintelen.ch'; Joenet (E-mail)
> Subject: Re: [JN] Parallel Triode
>
>
> Christian Rintelen wrote:
>
> >>>
> Here comes the interesting part as Lynn continues: "...and
> the cathodes are
> tied together as well, small differences in transconductance
> can multiply to
> large differences in current, with 30% imbalance not being
> unusual. This is the
> downfall of the typical parallel connection, for example. (Matt Kamna
> discovered the large differences in parallel-connected
> triodes as part of
> another project in researching parallel SE.)"
> <<<
>
> I believe it was Lynn & Matt who published an article last
> year on the importance of matching triodes used in parallel,
> it was in Glass Audio.
>
> I will try this in my tweaked-up Free Lunch Double Darling,
> which, although decent, has not been floating my boat all the
> way to the surface lately. I wonder what value of series
> resistor to use?
>
> This is a PSE circuit, with two 1626's connected in parallel
> to a "Champ" output transformer of something like 5K:8 ratio.
>
> As a WAG I was going to try 500 ohm R's in series with the
> plates of each 1626, which are not matched, unless by
> accident. Anybody have any reason to try anything different?
>
> -j
> =========================================
> Jeremy Epstein........jepstein@ndbcap.com
> =========================================
=========================================================================
From: "Epstein, Jeremy" <JEpstein@ndbcap.com>
Subject: RE: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 10:59:15 -0500
Source: Sound Digest Archive v02.n793
I also did not expect much from doing the math, agreed. I guess the drop is
about 5V with mine, 200 ohms at ~25mA. Perhaps there is a feedback mechanism
between the plates that is better this way than a direct connection?
WTFDIK? I will listen some more (and I have some folks stopping by this
weekend, we will see what they hear.)
- -j
=========================================
Jeremy Epstein........jepstein@ndbcap.com
=========================================
> -----Original Message-----
> From: Bart Shepherd (Home) [mailto:bart.s@bigpond.net.au]
> Sent: Friday, January 26, 2001 10:40 AM
> To: Epstein, Jeremy; christian@rintelen.ch; 'Joenet (E-mail)';
> lynno@teleport.com
> Subject: RE: Re: [JN] Parallel Triode
>
>
> Wow, I'm not knocking what you heard, I just find this really hard to
> figure.
>
> What measurable difference do these resistors make? What is
> the voltage drop
> across each? How can they do much in the plate circuit where they have
> little if any effect on bias or current flow? Isn't their
> effect swamped by
> the impedance of the output transformer or load resistor?
>
> Lets imagine you have really unbalanced tubes with one
> conducting double the
> current of the other, what happens with these R's???
>
> Lets say a 5K load and 40ma through one and 20ma through the other.
> Identical plate and bias volts before adding the two R's. My
> quick calc says
> we are going to get all of 4V difference in plate voltages
> with whatever
> difference in biasing and current this will cause. It's not
> going to be
> much.
>
> I would have thought a better approach might be to use
> separate cathode
> resistors and adjust them until the same, desired, voltage
> drop across them.
>
> Ive come in late without the background on this or knowing
> the circuit. Am I
> missing something here?
>
> Cheers,
>
> Bart
>
>
> Cheers,
>
> Bart
>
>
> -----Original Message-----
> From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
> Behalf Of Epstein, Jeremy
> Sent: Saturday, 27 January 2001 1:31 AM
> To: 'christian@rintelen.ch'; 'Joenet (E-mail)'; 'lynno@teleport.com'
> Subject: RE: Re: [JN] Parallel Triode
>
>
> Well, I tried this last night, I used 200 ohm resistors in
> series with the
> plates of the 1626's (I had 4 of the 200 ohm parts handy) and it works
> pretty well from what I heard in a few short listens last
> night and this AM.
> (My wife wanted me to come up and watch ER with her so last
> night was cut
> short.)
>
> My initial impression is that it helps significantly to focus
> the sound. I
> listened to Mal Waldron & John Coltrane (a mono jazz LP) and I heard a
> better focus on Coltrane's horn and a more coherent mono
> image, centered
> better and just a little more unified. Overall I found it to be an
> improvement. I heard a distortion on a couple of piano riffs
> which I need to
> find out about - it may be in the record, it may be something I have
> introduced, I will listen to some other discs and see what happens.
>
> Note this was in an amp which I (and others) had thought had a problem
> exactly with this "smearing" issue, a DC Double Darling. Probably, the
> better you match the tubes involved, the less you have to
> worry about this
> but in my case it seems to be a good idea. Anybody have any
> idea how to
> optimize the value of this resistor?
>
> -j
>
> > -----Original Message-----
> > From: Epstein, Jeremy
> > Sent: Thursday, January 25, 2001 1:10 PM
> > To: 'christian@rintelen.ch'; Joenet (E-mail)
> > Subject: Re: [JN] Parallel Triode
> >
> >
> > Christian Rintelen wrote:
> >
> > >>>
> > Here comes the interesting part as Lynn continues: "...and
> > the cathodes are
> > tied together as well, small differences in transconductance
> > can multiply to
> > large differences in current, with 30% imbalance not being
> > unusual. This is the
> > downfall of the typical parallel connection, for example.
> (Matt Kamna
> > discovered the large differences in parallel-connected
> > triodes as part of
> > another project in researching parallel SE.)"
> > <<<
> >
> > I believe it was Lynn & Matt who published an article last
> > year on the importance of matching triodes used in parallel,
> > it was in Glass Audio.
> >
> > I will try this in my tweaked-up Free Lunch Double Darling,
> > which, although decent, has not been floating my boat all the
> > way to the surface lately. I wonder what value of series
> > resistor to use?
> >
> > This is a PSE circuit, with two 1626's connected in parallel
> > to a "Champ" output transformer of something like 5K:8 ratio.
> >
> > As a WAG I was going to try 500 ohm R's in series with the
> > plates of each 1626, which are not matched, unless by
> > accident. Anybody have any reason to try anything different?
> >
> > -j
> > =========================================
> > Jeremy Epstein........jepstein@ndbcap.com
> > =========================================
>
=========================================================================
From: "Bart Shepherd \(Home\)" <bart.s@bigpond.net.au>
Subject: RE: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 11:34:13 +1100
Source: Sound Digest Archive v02.n793
>
also twice as difficult to drive... so be aware of the preceeding stage,
grid resistor etc.
>
Yes, often overlooked.
>
i always hear of the bluured sound with paralleled triodes... but i have
never seen people double the drive when they double the tube... i wonder if
thats whats blurring the sound?
dave
>
I use a parallel 6SN7 cathode follower as a direct coupled 211 driver with
fixed bias and it sounds great but this has naturally high input impedance.
This subject is another case of measured vs heard.
Dave, did you read the study of parallel tubes in G.A.? Very extensive and
concluded the distortion is the average distortion of the two halves. i.e.
not increased.
Cheers,
Bart
=========================================================================
From: "Bart Shepherd \(Home\)" <bart.s@bigpond.net.au>
Subject: RE: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 11:51:15 +1100
Source: Sound Digest Archive v02.n793
And importantly, did you hear any blurring!!!!!????
- -----Original Message-----
From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
Behalf Of Danielak, Robert M
Sent: Friday, 26 January 2001 3:25 AM
To: sound@deliverator.io.com; 'dslagle@earthlink.net'
Subject: RE: [JN] Parallel Triode
> ----------
> From: dslagle@earthlink.net[SMTP:dslagle@earthlink.net]
> Sent: Thursday, January 25, 2001 7:49 AM
> To: sound@deliverator.io.com
> Subject: RE: [JN] Parallel Triode
>
>
> also twice as difficult to drive... so be aware of the preceeding stage,
> grid resistor etc.
>
> i always hear of the bluured sound with paralleled triodes... but i have
> never seen people double the drive when they double the tube... i wonder
> if
> thats whats blurring the sound?
>
> dave
>
>
hey, wait a minute...
i *tripled* the drive
when i used *five* parallel output tubes
in my D3.5:
http://www.geocities.com/bobdanielak/darling.html
fwiw, i still prefer the single SE version.
i'd like it to be easy to get the same sound as single SE
- -but with more power-
by simply paralleling output tubes, but this has not been my experience.
even with two tubes in parallel.
you seem to loose something.
also, i'm not exactly convinced that it is the paralleling of tubes.
it may simply be a function of the output power.
i have yet to build a higher power amp that has the same "fun-factor"
as the single SE.
perhaps it is related to my speakers.
they provide enough sound to fill my room at decent volume
even with only 0.7W on tap. and for most listening
they do a great job.
now plug in a PSE, or even a 45 or 2a3 amp, and they
obviously have more authority - due to their extra power,
but the "fun-factor" is not quite so high.
45 and 2a3 fans, do not lynch me, i'm talking 99% versus 100%
difference in "fun-factor".
it seems to me that if you can tolerate an amp that is not capable of
pushing your speakers to the point of noticeable distortion
you are better off than trying to control the level by backing off.
in this case, maybe headroom is not desireable.
just a thought....
bob.d.
=========================================================================
From: "Sellek, Grant (TSA)" <Grant.Sellek@transport.sa.gov.au>
Subject: RE: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 14:11:56 +1030
Source: Sound Digest Archive v02.n793
I remember a long email from jc morrison, in which he argued that
PSE gets unfair criticism. Here's jc (gramatically edited as a favour
to Jean-Michel):--
"You know, parallel output tubes have some serious advantages and some
equally heavy difficulties that are not well understood. The great
advantage that cannot be understated is that a lower impedance output
trannie becomes practical. The output tranny is the single greatest
disadvantage of a tube amp. It stores "lost" energy and releases it
haphazardly over time, in a mix of modulation functions and sum and
difference crap. It accents certain harmonics and it wipes out others. It
messes with the time domain and it puts an unnatural cap on the bandwidth
of an amp that the universe simply doesn't have. And it IS the known
universe that we are attempting to make an analogy for (albeit an
electrical analogy). And these things DO affect the quality of
reproduction.
"However, OTL amps have not managed to surpass a well designed
transformer coupled amp yet. (I think this mainly centers around the
inherent high impedance of vacuum tubes but there are also circuit problems
too. SEPP is a joke actually! Stupid overengineered worthless approach it
is. Although the circlotron circuit is excellent for OTL use as Ralph
Karsten has demonstrated...)
"Anyway, back to parallel tubes PP or SE. The
closer to a 1:1 ratio we wind the tranny, the better it works in every
regard (better, not perfect). Less parasitic stuff, less losses, less
energy storage problems. And the less back emf reflected to the output
tubes too (very important!). Less (impedance) is more when it comes to
output trannies. But tubes have parasites, losses and nonlinearities of
their own too. The grid to plate and plate to cathode capacitance forms
feedback paths that are both voltage variable and frequency dependent. with
triodes we get appreciable Miller effect. It's bad enough with one tube.
Paralleling tubes obviously greatly influences the load which the DRIVER
stage must deal with as well as the nonlinearities added to the mix. The
problem is subtly different with tetrodes and pentodes but it is still a
factor to be considered.
"So where do we look to balance these aspects of
tubes and transformers so that we can benefit? THE DRIVER STAGE!!!!!!!!!!
Forget about using a high mu triode or pentode or any high z source for a
parallel OPT stage. It's obvious why it doesn't sound too good. Cascading
low z low mu tubes (reduces miller and can provide some driving current)
gets the gain you need and if it still gets loaded down at the big swings,
then add some power (current times volts) to the mix. This can be a cathode
follower or a big ass power tube. Keep the grid leak as small as
possible!!! If this can be reduced without loading the driver you will
notice an immediate improvement. Notice i said: "without loading the
driver". Those of you into interstage tranformers will understand that the
low DCR of the grid return (the secondary) accomplishes this with flair.
Ever wonder why so many parallel 845 amps rely upon an interstage tranny? I
shoot for 50k max on output grids or I direct couple. 10k is better than
50k.
"In any case, there is nothing to be afraid of by parallel operation of
tubes. It just takes a little more planning. The chapter in the Radiotron
on Miller effect is excellent and simple and allows you to accurately
define the requirements for any given string of triode gain blocks. I hope
this helps a bit..."
Grant Sellek, Adelaide, Australia
>-----Original Message-----
>From: evaguido [mailto:EvaGuido@iaehv.nl]
>Sent: Friday, 26 January 2001 5:05 AM
>To: Andry Gunawan Satyaputra; sound@lists.io.com
>Subject: Re: [JN] Parallel Triode
>
>
>At 09:01 25-1-01 +0700, Andry Gunawan Satyaputra wrote:
>>Hi All,
>>what's the advantage if use parallel triode in driver stage ?
>
>Lower output impedance, higher transconductance
>
>Disadvantage: Paralleling low impedance devices is a diffcult job, as 2
>curves never fit.... (try to connect 2 lab supplies in
>parallel, that is,
>in voltage mode. One always wins, whatever happens.
>
>Now swittch the same supplies in current mode; you'll see no problems
>
>If low output impedance is required it may be better to find
>another tube /
>circuit
>
>Have fun
>
>Guido
=========================================================================
From: "Remco Stoutjesdijk" <r.m.stoutjesdijk@student.utwente.nl>
Subject: RE: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 16:17:56 +0100
Source: Sound Digest Archive v02.n793
Hi,
> Probably, the
> better you match the tubes involved, the less you have to
> worry about this
I get the feeling matching in PSE is more important than matching for
PP...!?
> Anybody have any
> idea how to
> optimize the value of this resistor?
Just guessing, have no experience in this, but maybe a pot? Both ends at
both tubes, and the wiper to the anode voltage?
Regards,
Remco
- --
http://listen.to/rmsaudio
=========================================================================
From: "Bart Shepherd \(Home\)" <bart.s@bigpond.net.au>
Subject: RE: Re: [JN] Parallel Triode
Date: Sat, 27 Jan 2001 02:39:59 +1100
Source: Sound Digest Archive v02.n793
Wow, I'm not knocking what you heard, I just find this really hard to
figure.
What measurable difference do these resistors make? What is the voltage drop
across each? How can they do much in the plate circuit where they have
little if any effect on bias or current flow? Isn't their effect swamped by
the impedance of the output transformer or load resistor?
Lets imagine you have really unbalanced tubes with one conducting double the
current of the other, what happens with these R's???
Lets say a 5K load and 40ma through one and 20ma through the other.
Identical plate and bias volts before adding the two R's. My quick calc says
we are going to get all of 4V difference in plate voltages with whatever
difference in biasing and current this will cause. It's not going to be
much.
I would have thought a better approach might be to use separate cathode
resistors and adjust them until the same, desired, voltage drop across them.
Ive come in late without the background on this or knowing the circuit. Am I
missing something here?
Cheers,
Bart
Cheers,
Bart
- -----Original Message-----
From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
Behalf Of Epstein, Jeremy
Sent: Saturday, 27 January 2001 1:31 AM
To: 'christian@rintelen.ch'; 'Joenet (E-mail)'; 'lynno@teleport.com'
Subject: RE: Re: [JN] Parallel Triode
Well, I tried this last night, I used 200 ohm resistors in series with the
plates of the 1626's (I had 4 of the 200 ohm parts handy) and it works
pretty well from what I heard in a few short listens last night and this AM.
(My wife wanted me to come up and watch ER with her so last night was cut
short.)
My initial impression is that it helps significantly to focus the sound. I
listened to Mal Waldron & John Coltrane (a mono jazz LP) and I heard a
better focus on Coltrane's horn and a more coherent mono image, centered
better and just a little more unified. Overall I found it to be an
improvement. I heard a distortion on a couple of piano riffs which I need to
find out about - it may be in the record, it may be something I have
introduced, I will listen to some other discs and see what happens.
Note this was in an amp which I (and others) had thought had a problem
exactly with this "smearing" issue, a DC Double Darling. Probably, the
better you match the tubes involved, the less you have to worry about this
but in my case it seems to be a good idea. Anybody have any idea how to
optimize the value of this resistor?
- -j
> -----Original Message-----
> From: Epstein, Jeremy
> Sent: Thursday, January 25, 2001 1:10 PM
> To: 'christian@rintelen.ch'; Joenet (E-mail)
> Subject: Re: [JN] Parallel Triode
>
>
> Christian Rintelen wrote:
>
> >>>
> Here comes the interesting part as Lynn continues: "...and
> the cathodes are
> tied together as well, small differences in transconductance
> can multiply to
> large differences in current, with 30% imbalance not being
> unusual. This is the
> downfall of the typical parallel connection, for example. (Matt Kamna
> discovered the large differences in parallel-connected
> triodes as part of
> another project in researching parallel SE.)"
> <<<
>
> I believe it was Lynn & Matt who published an article last
> year on the importance of matching triodes used in parallel,
> it was in Glass Audio.
>
> I will try this in my tweaked-up Free Lunch Double Darling,
> which, although decent, has not been floating my boat all the
> way to the surface lately. I wonder what value of series
> resistor to use?
>
> This is a PSE circuit, with two 1626's connected in parallel
> to a "Champ" output transformer of something like 5K:8 ratio.
>
> As a WAG I was going to try 500 ohm R's in series with the
> plates of each 1626, which are not matched, unless by
> accident. Anybody have any reason to try anything different?
>
> -j
> =========================================
> Jeremy Epstein........jepstein@ndbcap.com
> =========================================
=========================================================================
From: "Epstein, Jeremy" <JEpstein@ndbcap.com>
Subject: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 11:50:03 -0500
Source: Sound Digest Archive v02.n794
Christian Rintelen <christian@rintelen.ch> wrote:
>>>.... Here's what Lynn when I asked him the same
question two years ago: "The resistor between the audio path and the AF
chokes
provide a degree of isolation between audio and the small but significant
stray
C in the AF choke. This stray C, although small, is not very high quality
and
contributes to the "choke" sound. In addition, the resistor prevents the
load
from being purely reactive to the plates, and assumes finite values at very
high and very frequencies."
(I understand that Lynn chose not only to deal with the question of what
core
material contibutes favourably to the "choke sound", but also which resistor
sounds least obtrusive. No need to laugh, Mr. Slagle!.... ;-)
<<<
I have always placed the resistor at the "top" between the AC ground and the
choke, then the tube's plate comes last. I suppose I had better switch it
around and see whether Lynn-O is right!
- -j
=========================================
Jeremy Epstein........jepstein@ndbcap.com
=========================================
=========================================================================
From: dslagle@earthlink.net (dave slagle)
Subject: RE: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 13:04:23 -0500
Source: Sound Digest Archive v02.n794
>I would have thought a better approach might be to use separate cathode
>resistors and adjust them until the same, desired, voltage drop across them.
maybe you could use a properly sided rheostat between the cathodes with the
wiper grounded, then you could "dial" in the proper matched current... what
i want to know is how does matching the current guarentee similar
anything... unless you trace the curves to match your tubes in the fiirst
place... sure you have a better chance of feeling good about it, but what
does it actually tell you?
i really liked the repost of JC, and i side with him... the OT is the big
weakness... and reducing its compromise may be where the great improvements
are to be made.... that OT iron is doing a hell of alot more to your sound
than any paralleled tube ever will.... yvmv
dave
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 15:18:27 -0500
Source: Sound Digest Archive v02.n794
evaguido wrote:
>
> Good experiemnt Jeremy !
>
> >(My wife wanted me to come up and watch ER with her so last night was cut
> short.)
>
> She was right, you should relax a while sometimes....
Yeah, but watching ER?
JL
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: RE: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 19:38:01 +0100
Source: Sound Digest Archive v02.n794
At 09:30 26-1-01 -0500, Epstein, Jeremy wrote:
>Well, I tried this last night, I used 200 ohm resistors in series with the
>plates of the 1626's (I had 4 of the 200 ohm parts handy) and it works
>pretty well from what I heard in a few short listens last night and this AM.
Good experiemnt Jeremy !
>(My wife wanted me to come up and watch ER with her so last night was cut
short.)
She was right, you should relax a while sometimes....
>My initial impression is that it helps significantly to focus the sound. I
>listened to Mal Waldron & John Coltrane (a mono jazz LP) and I heard a
>better focus on Coltrane's horn and a more coherent mono image, centered
>better and just a little more unified. Overall I found it to be an
>improvement. I heard a distortion on a couple of piano riffs which I need to
>find out about - it may be in the record, it may be something I have
>introduced, I will listen to some other discs and see what happens.
It raises Rp and therefor makes matching less critical as the error current
due to mismatch becomes smaller
I suggest you try adding a resistor with value Rp instead of 220 ohm
>Note this was in an amp which I (and others) had thought had a problem
>exactly with this "smearing" issue, a DC Double Darling. Probably, the
>better you match the tubes involved, the less you have to worry about this
Bingo !
>but in my case it seems to be a good idea. Anybody have any idea how to
>optimize the value of this resistor?
Take a stereo potentiometer, sit down in your favourite chair, ask Ellen to
turn the pot gently. Find optimum value. Switch of amplifier and watch next
series of ER.
Note: Increasing series resistor decreases anode voltage.....
Guido
>-j
>
>> -----Original Message-----
>> From: Epstein, Jeremy
>> Sent: Thursday, January 25, 2001 1:10 PM
>> To: 'christian@rintelen.ch'; Joenet (E-mail)
>> Subject: Re: [JN] Parallel Triode
>>
>>
>> Christian Rintelen wrote:
>>
>> >>>
>> Here comes the interesting part as Lynn continues: "...and
>> the cathodes are
>> tied together as well, small differences in transconductance
>> can multiply to
>> large differences in current, with 30% imbalance not being
>> unusual. This is the
>> downfall of the typical parallel connection, for example. (Matt Kamna
>> discovered the large differences in parallel-connected
>> triodes as part of
>> another project in researching parallel SE.)"
>> <<<
>>
>> I believe it was Lynn & Matt who published an article last
>> year on the importance of matching triodes used in parallel,
>> it was in Glass Audio.
>>
>> I will try this in my tweaked-up Free Lunch Double Darling,
>> which, although decent, has not been floating my boat all the
>> way to the surface lately. I wonder what value of series
>> resistor to use?
>>
>> This is a PSE circuit, with two 1626's connected in parallel
>> to a "Champ" output transformer of something like 5K:8 ratio.
>>
>> As a WAG I was going to try 500 ohm R's in series with the
>> plates of each 1626, which are not matched, unless by
>> accident. Anybody have any reason to try anything different?
>>
>> -j
>> =========================================
>> Jeremy Epstein........jepstein@ndbcap.com
>> =========================================
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: RE: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 19:41:12 +0100
Source: Sound Digest Archive v02.n794
At 16:17 26-1-01 +0100, Remco Stoutjesdijk wrote:
>Hi,
>
>> Probably, the
>> better you match the tubes involved, the less you have to
>> worry about this
>
>I get the feeling matching in PSE is more important than matching for
>PP...!?
Why would that be ? In PP you'll never be able to match the curves as you
walk through both curves in antiphase............
>> Anybody have any
>> idea how to
>> optimize the value of this resistor?
>
>Just guessing, have no experience in this, but maybe a pot? Both ends at
>both tubes, and the wiper to the anode voltage?
Mmmh. i guess Jeremy carried out a slightly different experiment, he added
series resistance in each of the tubes. Now you suggest optimising both
values for minmum distortion - also worth a try but I'dd suggest to do that
balance act at the cathodes
Food for thought anyhow
Guido
>Regards,
>Remco
>--
>http://listen.to/rmsaudio
>
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: RE: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 19:43:02 +0100
Source: Sound Digest Archive v02.n794
At 02:39 27-1-01 +1100, Bart Shepherd (Home) wrote:
>Lets imagine you have really unbalanced tubes with one conducting double the
>current of the other, what happens with these R's???
>
>Lets say a 5K load and 40ma through one and 20ma through the other.
>Identical plate and bias volts before adding the two R's. My quick calc says
>we are going to get all of 4V difference in plate voltages with whatever
>difference in biasing and current this will cause. It's not going to be
>much.
The plate impedances rise and therefor parallellling the tubes becomes less
critical
>I would have thought a better approach might be to use separate cathode
>resistors and adjust them until the same, desired, voltage drop across them.
That is to match the DC current. The problem however lies within matching
the ac behaviour, which depends on 2 curves and the external circuiit - not
easy....
Guido
>Ive come in late without the background on this or knowing the circuit. Am I
>missing something here?
>
>Cheers,
>
>Bart
>
>
>Cheers,
>
>Bart
>
>
>-----Original Message-----
>From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
>Behalf Of Epstein, Jeremy
>Sent: Saturday, 27 January 2001 1:31 AM
>To: 'christian@rintelen.ch'; 'Joenet (E-mail)'; 'lynno@teleport.com'
>Subject: RE: Re: [JN] Parallel Triode
>
>
>Well, I tried this last night, I used 200 ohm resistors in series with the
>plates of the 1626's (I had 4 of the 200 ohm parts handy) and it works
>pretty well from what I heard in a few short listens last night and this AM.
>(My wife wanted me to come up and watch ER with her so last night was cut
>short.)
>
>My initial impression is that it helps significantly to focus the sound. I
>listened to Mal Waldron & John Coltrane (a mono jazz LP) and I heard a
>better focus on Coltrane's horn and a more coherent mono image, centered
>better and just a little more unified. Overall I found it to be an
>improvement. I heard a distortion on a couple of piano riffs which I need to
>find out about - it may be in the record, it may be something I have
>introduced, I will listen to some other discs and see what happens.
>
>Note this was in an amp which I (and others) had thought had a problem
>exactly with this "smearing" issue, a DC Double Darling. Probably, the
>better you match the tubes involved, the less you have to worry about this
>but in my case it seems to be a good idea. Anybody have any idea how to
>optimize the value of this resistor?
>
>-j
>
>> -----Original Message-----
>> From: Epstein, Jeremy
>> Sent: Thursday, January 25, 2001 1:10 PM
>> To: 'christian@rintelen.ch'; Joenet (E-mail)
>> Subject: Re: [JN] Parallel Triode
>>
>>
>> Christian Rintelen wrote:
>>
>> >>>
>> Here comes the interesting part as Lynn continues: "...and
>> the cathodes are
>> tied together as well, small differences in transconductance
>> can multiply to
>> large differences in current, with 30% imbalance not being
>> unusual. This is the
>> downfall of the typical parallel connection, for example. (Matt Kamna
>> discovered the large differences in parallel-connected
>> triodes as part of
>> another project in researching parallel SE.)"
>> <<<
>>
>> I believe it was Lynn & Matt who published an article last
>> year on the importance of matching triodes used in parallel,
>> it was in Glass Audio.
>>
>> I will try this in my tweaked-up Free Lunch Double Darling,
>> which, although decent, has not been floating my boat all the
>> way to the surface lately. I wonder what value of series
>> resistor to use?
>>
>> This is a PSE circuit, with two 1626's connected in parallel
>> to a "Champ" output transformer of something like 5K:8 ratio.
>>
>> As a WAG I was going to try 500 ohm R's in series with the
>> plates of each 1626, which are not matched, unless by
>> accident. Anybody have any reason to try anything different?
>>
>> -j
>> =========================================
>> Jeremy Epstein........jepstein@ndbcap.com
>> =========================================
>
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 19:45:40 +0100
Source: Sound Digest Archive v02.n794
At 11:50 26-1-01 -0500, Epstein, Jeremy wrote:
>I have always placed the resistor at the "top" between the AC ground and the
>choke, then the tube's plate comes last. I suppose I had better switch it
>around and see whether Lynn-O is right!
My suggestion would be to add the resistor at the point that moves fast,
voltage wise.
Guido
>-j
>=========================================
>Jeremy Epstein........jepstein@ndbcap.com
>=========================================
=========================================================================
From: Phil <tube@jump.net>
Subject: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 21:44:34 -0600
Source: Sound Digest Archive v02.n794
Jeremy,
If we accept the truth, namely that two tubes in parallel don't sound
as good as one, then there has to be some reason why this is so. I
don't know what that reason is, but I have an idea or two about things
that *might* be the reason, if you feel like some random experimenting.
The gain of two tubes is almost always a little different, as is the
input capacitance. The Miller effect multiplies the grid-plate cap by
the amplifier gain, which in turn multiplies the difference in input
capacitance between the two tubes. If this difference is great enough,
and you have a 1 K grid-stopper resistor on each grid, then the time
delay through the two tubes will be different.
Now I hate to beat a dead horse--okay, no lies, I actually *love*
beating dead horses--but if the musical signal exits from the two tubes
at different times, then when the two outputs combine, the original
signal is going to get smeared. Using plate resistors will allow each
tube to have its "natural" gain x Cgp, which may help to equalize the
delay between the tubes, but why use such an indirect approach? If you
put two capacitors from grid to cathode on each tube, and make one of
them variable, then adjusting the variable will allow you to "speed up
or slow down" that tube, so that the exit time for both tubes is
exactly the same, at least at low signal levels (as the signal gets
bigger, the odds of both time-constants remaining the same drops). Now
I don't think that the difference in Cgp will be bigger than 1 or 2 pF,
but you have to multiply this by the gain, so it might be necessary to
put 10pF on one tube, with a 20 pF variable on the other (but just 5 pF
and 10 pF variable would probably work).
This puts more demand on the driver stage, of course, but since it is
not from grid to plate it does not get multiplied by the gain. Also, I
think it would enhance stability, like a grid stop resistor or ferrite
bead, since it would resist feedback from the plate. I don't really
know about how RF works, though, so it might not.
Phil
"Epstein, Jeremy" wrote:
> Well, I tried this last night, I used 200 ohm resistors in series with the
> plates of the 1626's (I had 4 of the 200 ohm parts handy) and it works
> pretty well from what I heard in a few short listens last night and this AM.
> (My wife wanted me to come up and watch ER with her so last night was cut
> short.)
>
> My initial impression is that it helps significantly to focus the sound. I
> listened to Mal Waldron & John Coltrane (a mono jazz LP) and I heard a
> better focus on Coltrane's horn and a more coherent mono image, centered
> better and just a little more unified. Overall I found it to be an
> improvement. I heard a distortion on a couple of piano riffs which I need to
> find out about - it may be in the record, it may be something I have
> introduced, I will listen to some other discs and see what happens.
>
> Note this was in an amp which I (and others) had thought had a problem
> exactly with this "smearing" issue, a DC Double Darling. Probably, the
> better you match the tubes involved, the less you have to worry about this
> but in my case it seems to be a good idea. Anybody have any idea how to
> optimize the value of this resistor?
>
> -j
>
> > -----Original Message-----
> > From: Epstein, Jeremy
> > Sent: Thursday, January 25, 2001 1:10 PM
> > To: 'christian@rintelen.ch'; Joenet (E-mail)
> > Subject: Re: [JN] Parallel Triode
> >
> >
> > Christian Rintelen wrote:
> >
> > >>>
> > Here comes the interesting part as Lynn continues: "...and
> > the cathodes are
> > tied together as well, small differences in transconductance
> > can multiply to
> > large differences in current, with 30% imbalance not being
> > unusual. This is the
> > downfall of the typical parallel connection, for example. (Matt Kamna
> > discovered the large differences in parallel-connected
> > triodes as part of
> > another project in researching parallel SE.)"
> > <<<
> >
> > I believe it was Lynn & Matt who published an article last
> > year on the importance of matching triodes used in parallel,
> > it was in Glass Audio.
> >
> > I will try this in my tweaked-up Free Lunch Double Darling,
> > which, although decent, has not been floating my boat all the
> > way to the surface lately. I wonder what value of series
> > resistor to use?
> >
> > This is a PSE circuit, with two 1626's connected in parallel
> > to a "Champ" output transformer of something like 5K:8 ratio.
> >
> > As a WAG I was going to try 500 ohm R's in series with the
> > plates of each 1626, which are not matched, unless by
> > accident. Anybody have any reason to try anything different?
> >
> > -j
> > =========================================
> > Jeremy Epstein........jepstein@ndbcap.com
> > =========================================
=========================================================================
From: "Paul Croft" <pcroft@iximd.com>
Subject: RE: Re: [JN] Parallel Triode
Date: Fri, 26 Jan 2001 23:19:42 -0500
Source: Sound Digest Archive v02.n794
Hi Jeremy,
WTFDIK???? I love it!!!!
Cheers,
Paul
> -----Original Message-----
> From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
> Behalf Of Epstein, Jeremy
> Sent: Friday, January 26, 2001 10:59 AM
> To: 'Bart Shepherd (Home)'; Joenet (E-mail)
> Subject: RE: Re: [JN] Parallel Triode
>
>
> I also did not expect much from doing the math, agreed. I guess
> the drop is
> about 5V with mine, 200 ohms at ~25mA. Perhaps there is a
> feedback mechanism
> between the plates that is better this way than a direct connection?
>
> WTFDIK? I will listen some more (and I have some folks stopping by this
> weekend, we will see what they hear.)
>
> -j
> =========================================
> Jeremy Epstein........jepstein@ndbcap.com
> =========================================
>
>
> > -----Original Message-----
> > From: Bart Shepherd (Home) [mailto:bart.s@bigpond.net.au]
> > Sent: Friday, January 26, 2001 10:40 AM
> > To: Epstein, Jeremy; christian@rintelen.ch; 'Joenet (E-mail)';
> > lynno@teleport.com
> > Subject: RE: Re: [JN] Parallel Triode
> >
> >
> > Wow, I'm not knocking what you heard, I just find this really hard to
> > figure.
> >
> > What measurable difference do these resistors make? What is
> > the voltage drop
> > across each? How can they do much in the plate circuit where they have
> > little if any effect on bias or current flow? Isn't their
> > effect swamped by
> > the impedance of the output transformer or load resistor?
> >
> > Lets imagine you have really unbalanced tubes with one
> > conducting double the
> > current of the other, what happens with these R's???
> >
> > Lets say a 5K load and 40ma through one and 20ma through the other.
> > Identical plate and bias volts before adding the two R's. My
> > quick calc says
> > we are going to get all of 4V difference in plate voltages
> > with whatever
> > difference in biasing and current this will cause. It's not
> > going to be
> > much.
> >
> > I would have thought a better approach might be to use
> > separate cathode
> > resistors and adjust them until the same, desired, voltage
> > drop across them.
> >
> > Ive come in late without the background on this or knowing
> > the circuit. Am I
> > missing something here?
> >
> > Cheers,
> >
> > Bart
> >
> >
> > Cheers,
> >
> > Bart
> >
> >
> > -----Original Message-----
> > From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
> > Behalf Of Epstein, Jeremy
> > Sent: Saturday, 27 January 2001 1:31 AM
> > To: 'christian@rintelen.ch'; 'Joenet (E-mail)'; 'lynno@teleport.com'
> > Subject: RE: Re: [JN] Parallel Triode
> >
> >
> > Well, I tried this last night, I used 200 ohm resistors in
> > series with the
> > plates of the 1626's (I had 4 of the 200 ohm parts handy) and it works
> > pretty well from what I heard in a few short listens last
> > night and this AM.
> > (My wife wanted me to come up and watch ER with her so last
> > night was cut
> > short.)
> >
> > My initial impression is that it helps significantly to focus
> > the sound. I
> > listened to Mal Waldron & John Coltrane (a mono jazz LP) and I heard a
> > better focus on Coltrane's horn and a more coherent mono
> > image, centered
> > better and just a little more unified. Overall I found it to be an
> > improvement. I heard a distortion on a couple of piano riffs
> > which I need to
> > find out about - it may be in the record, it may be something I have
> > introduced, I will listen to some other discs and see what happens.
> >
> > Note this was in an amp which I (and others) had thought had a problem
> > exactly with this "smearing" issue, a DC Double Darling. Probably, the
> > better you match the tubes involved, the less you have to
> > worry about this
> > but in my case it seems to be a good idea. Anybody have any
> > idea how to
> > optimize the value of this resistor?
> >
> > -j
> >
> > > -----Original Message-----
> > > From: Epstein, Jeremy
> > > Sent: Thursday, January 25, 2001 1:10 PM
> > > To: 'christian@rintelen.ch'; Joenet (E-mail)
> > > Subject: Re: [JN] Parallel Triode
> > >
> > >
> > > Christian Rintelen wrote:
> > >
> > > >>>
> > > Here comes the interesting part as Lynn continues: "...and
> > > the cathodes are
> > > tied together as well, small differences in transconductance
> > > can multiply to
> > > large differences in current, with 30% imbalance not being
> > > unusual. This is the
> > > downfall of the typical parallel connection, for example.
> > (Matt Kamna
> > > discovered the large differences in parallel-connected
> > > triodes as part of
> > > another project in researching parallel SE.)"
> > > <<<
> > >
> > > I believe it was Lynn & Matt who published an article last
> > > year on the importance of matching triodes used in parallel,
> > > it was in Glass Audio.
> > >
> > > I will try this in my tweaked-up Free Lunch Double Darling,
> > > which, although decent, has not been floating my boat all the
> > > way to the surface lately. I wonder what value of series
> > > resistor to use?
> > >
> > > This is a PSE circuit, with two 1626's connected in parallel
> > > to a "Champ" output transformer of something like 5K:8 ratio.
> > >
> > > As a WAG I was going to try 500 ohm R's in series with the
> > > plates of each 1626, which are not matched, unless by
> > > accident. Anybody have any reason to try anything different?
> > >
> > > -j
> > > =========================================
> > > Jeremy Epstein........jepstein@ndbcap.com
> > > =========================================
> >
>
=========================================================================
From: "Bart Shepherd \(Home\)" <bart.s@bigpond.net.au>
Subject: RE: Re: [JN] Parallel Triode
Date: Sat, 27 Jan 2001 11:45:53 +1100
Source: Sound Digest Archive v02.n794
Dave,
I agree with all your points.
But we assume we already have the iron we have and think we can remove some
"blurr".
You are correct so the "dialling up" may be best done by ear!
Bart
- -----Original Message-----
From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
Behalf Of dave slagle
Sent: Saturday, 27 January 2001 5:04 AM
To: sound@deliverator.io.com
Subject: RE: Re: [JN] Parallel Triode
>I would have thought a better approach might be to use separate cathode
>resistors and adjust them until the same, desired, voltage drop across
them.
maybe you could use a properly sided rheostat between the cathodes with the
wiper grounded, then you could "dial" in the proper matched current... what
i want to know is how does matching the current guarentee similar
anything... unless you trace the curves to match your tubes in the fiirst
place... sure you have a better chance of feeling good about it, but what
does it actually tell you?
i really liked the repost of JC, and i side with him... the OT is the big
weakness... and reducing its compromise may be where the great improvements
are to be made.... that OT iron is doing a hell of alot more to your sound
than any paralleled tube ever will.... yvmv
dave
=========================================================================
From: "Bart Shepherd \(Home\)" <bart.s@bigpond.net.au>
Subject: RE: Re: [JN] Parallel Triode
Date: Sat, 27 Jan 2001 11:51:44 +1100
Source: Sound Digest Archive v02.n794
From Guido,
>
That is to match the DC current. The problem however lies within matching
the ac behaviour, which depends on 2 curves and the external circuiit - not
easy....
>
This is an enormously important point that I had completely overlooked.
I still think the cathode thing is worth trying but will need to be a split
bias R with the adjustment portion unbypassed.
Bart
=========================================================================
From: "Bart Shepherd \(Home\)" <bart.s@bigpond.net.au>
Subject: RE: Re: [JN] Parallel Triode
Date: Sat, 27 Jan 2001 11:59:27 +1100
Source: Sound Digest Archive v02.n794
>
I suggest you try adding a resistor with value Rp instead of 220 ohm
>
This could lose around 20% of the power.
Why not address the problem from the other end? Surely a bit of feedback
will supply some leverage and little power loss.
Bart
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: RE: Re: [JN] Parallel Triode
Date: Sun, 28 Jan 2001 15:45:03 +0100
Source: Sound Digest Archive v02.n795
At 11:51 27-1-01 +1100, Bart Shepherd (Home) wrote:
>
>>From Guido,
>>
>That is to match the DC current. The problem however lies within matching
>the ac behaviour, which depends on 2 curves and the external circuiit - not
>easy....
>>
>
>This is an enormously important point that I had completely overlooked.
>
>I still think the cathode thing is worth trying but will need to be a split
>bias R with the adjustment portion unbypassed.
Works fine too, yes
Guido
>Bart
>
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: RE: Re: [JN] Parallel Triode
Date: Sun, 28 Jan 2001 15:46:51 +0100
Source: Sound Digest Archive v02.n795
At 11:59 27-1-01 +1100, Bart Shepherd (Home) wrote:
>
>>
>I suggest you try adding a resistor with value Rp instead of 220 ohm
>>
>
>This could lose around 20% of the power.
True, but do we care ...... ?
>Why not address the problem from the other end? Surely a bit of feedback
>will supply some leverage and little power loss.
I don not agree here. Applying feedback does not improve matching, only
"cures" things that are wrong anyhow....
Enjoy
Guido
>Bart
>
>
>
>
=========================================================================
From: "Le Cleac'h Jean-Michel" <lecleach@paris.ensmp.fr>
Subject: Re: [JN] Parallel Triode
Date: Mon, 29 Jan 2001 13:54:28 +0100
Source: Sound Digest Archive v02.n795
- -----Message d'origine-----
De : Sellek, Grant (TSA) <Grant.Sellek@transport.sa.gov.au>
À : sound@lists.io.com <sound@lists.io.com>
Date : vendredi 26 janvier 2001 05:05
Objet : RE: [JN] Parallel Triode
>I remember a long email from jc morrison, in which he argued that
>PSE gets unfair criticism. Here's jc (gramatically edited as a favour
>to Jean-Michel):--
Dear Grant,
Thanks a lot for that.
Most often I find that what J.C.'thoughts are clever and interesting but the
way his posts are written deserves their content.
Best regards,
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: Jim de Kort <sp@vt52.com>
Subject: [JN] parameters for PM4a
Date: Sun, 13 Aug 2000 15:27:50 +0200
Source: Sound Digest Archive v02.n625
Hi,
Does anyone know the parameters for the Lowther PM4A? I need Q/V/...
factors etc for calculations...
Regards,
Jim de Kort
jim@vt52.com
=========================================================================
From: "Verhoeff, A..A." <verhoeff@awvn.nl>
Subject: [JN] paraphase
Date: Wed, 17 Oct 2001 07:41:07 +0200
Source: Sound Digest Archive v02.n994
Hello,
The principle of paraphase to obtain a phase splitter has been discussed
here for tube designs (like Maggie).
I wonder if this principle is also applicable to SS designs. Never noticed
one, but didn't look either.
Just wondering, I like tubes better ;<)
Any thoughts?
Best regards, Arjen
======================================================================
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======================================================================
=========================================================================
From: "Phil Sieg" <triodelover@home.com>
Subject: [JN] Parasitic oscillations with DHTs?
Date: Fri, 21 Sep 2001 15:34:09 -0400
Source: Sound Digest Archive v02.n980
Joes,
<dreaded words to follow>
I am wrestling with a noise problem in the latest incarnation of my SE45
amps. Basically, it's a line input transformer (Peerless 15095, octal base)
to choke-loaded 45 grid parafeed IT-coupled to choke-loaded parafeed output.
And it buzzes - both channels. In a static bench test, scope shows a 1-2 mV
"spike" when set to 5mV/div. I've reworked grounds, checked solder
connections and am about to come to the conclusion that it's j's old friend,
parasitic oscillations.
Any of you guys had this type of problems with DHTs before? I've never seen
a grid stopper or ferrite beads used with DHTs. Anyone tried this?
Results? Any other thought?
TIA,
Phil
=========================================================================
From: Jeremy Epstein <jeremyepstein@earthlink.net>
Subject: [JN] Parasitic oscillations with DHTs?
Date: Sat, 22 Sep 2001 21:09:48 -0400
Source: Sound Digest Archive v02.n981
Phil wrote:
> I am wrestling with a noise problem in the latest incarnation of my SE45
> amps. Basically, it's a line input transformer (Peerless 15095, octal base)
> to choke-loaded 45 grid parafeed IT-coupled to choke-loaded parafeed output.
Is there another "45" belonging in that description - we have a two stage
amp, right? Step-up, 45, 45?
> And it buzzes - both channels. In a static bench test, scope shows a 1-2 mV
> "spike" when set to 5mV/div. I've reworked grounds, checked solder
> connections and am about to come to the conclusion that it's j's old friend,
> parasitic oscillations.
I would really not EXPECT that in a pair of low mu stages but I've been
wrong before. I'd be much more likely to expect -
1) silicon rectifier diode buzz, perhaps getting into the filament supplies
via the filament transformers, assuming you are using the dreaded silicon
rectifiers
2) magnetic coupling between power supply and some of that fat pile of iron
3) something funky to do with the interconnects - this last because you
probably use homebrew I/Cs like the rest of us mad cheapskates here and I
sometimes find that these give trouble when you least expect them to. Swap
in a pair of known good, shielded I/Cs before tearing up the amp too much.
4) I'm sure you know this already but the 1st filter cap's (-) terminal
connects directly to the power trans secondary center tap, nothing in
between, right? Then this spot goes to wahtever buss or star you are
grounding with?
5) Doc B always gets different results with grounding either (+) or (-) of
the output secondary but I think this is a very small effect, not a bad buzz
killing technique as you are describing.
- -j
=========================================================================
From: "Phil Sieg" <triodelover@home.com>
Subject: Re: [JN] Parasitic oscillations with DHTs?
Date: Sun, 23 Sep 2001 12:41:36 -0400
Source: Sound Digest Archive v02.n981
j,
>
> > I am wrestling with a noise problem in the latest incarnation of my SE45
> > amps. Basically, it's a line input transformer (Peerless 15095, octal
base)
> > to choke-loaded 45 grid parafeed IT-coupled to choke-loaded parafeed
output.
>
> Is there another "45" belonging in that description - we have a two stage
> amp, right? Step-up, 45, 45?
Step-up - 45 - IT - 45 - OPT
>
> > And it buzzes - both channels. In a static bench test, scope shows a 1-2
mV
> > "spike" when set to 5mV/div. I've reworked grounds, checked solder
> > connections and am about to come to the conclusion that it's j's old
friend,
> > parasitic oscillations.
>
> I would really not EXPECT that in a pair of low mu stages but I've been
> wrong before. I'd be much more likely to expect -
>
> 1) silicon rectifier diode buzz, perhaps getting into the filament
supplies
> via the filament transformers, assuming you are using the dreaded silicon
> rectifiers
Uses an 83 for B+, Schottkys for the filament supplies
> 2) magnetic coupling between power supply and some of that fat pile of
iron
Possible.
> 3) something funky to do with the interconnects - this last because you
> probably use homebrew I/Cs like the rest of us mad cheapskates here and I
> sometimes find that these give trouble when you least expect them to. Swap
> in a pair of known good, shielded I/Cs before tearing up the amp too much.
Yup, funky homebrew ICs, unshielded.
> 4) I'm sure you know this already but the 1st filter cap's (-) terminal
> connects directly to the power trans secondary center tap, nothing in
> between, right? Then this spot goes to wahtever buss or star you are
> grounding with?
Secondary CT is switch to ground. One switch to turn on the filaments, the
second switch to ground the CT. Filter caps go directly to the ground buss
which ties to chassis and AC ground. PS grounds closest to the AC ground on
the buss, signal path grounds farther away. But I'll try moving the 1st
cap's ground.
> 5) Doc B always gets different results with grounding either (+) or (-) of
> the output secondary but I think this is a very small effect, not a bad
buzz
> killing technique as you are describing.
Well, I've grounded the (-) secondary and got some reduction. Also found
tying the parafeed cap to ground rather than the top of the CR for the
output stage helped.
If it's the amps and not the ICs, I'm going to try Buddha's snubbers on both
the B+ and filament supplies and CMC in the B+ filter.
Phil
>
> -j
>
>
=========================================================================
From: rchamber@norwich.edu
Subject: Re: [JN] Parasitic oscillations with DHTs?
Date: Mon, 24 Sep 2001 12:47:13 GMT
Source: Sound Digest Archive v02.n981
"Phil Sieg"
<triodelover@h To: "Jeremy Epstein" <jeremyepstein@earthlink.net>, "J
oenet"
ome.com> <sound@lists.io.com>
Sent by: cc:
owner-sound@li Subject: Re: [JN] Parasitic oscillations with DHTs?
sts.io.com
09/23/2001
12:41 PM
CLIP
>> 2) magnetic coupling between power supply and some of that fat pile of
>>iron
>Possible.
I have just returned from 1937, reading in Terman's Radio Engineering. He
lists
the *principal disadvantage* of input and coupling transformers as well as
*impedance coupling* chokes as their propensity to pick up stray voltages.
Do you have some shielding cans you could try?
>> 3) something funky to do with the interconnects - this last because you
>> probably use homebrew I/Cs like the rest of us mad cheapskates here and
I
>> sometimes find that these give trouble when you least expect them to.
Swap
>> in a pair of known good, shielded I/Cs before tearing up the amp too
much.
>Yup, funky homebrew ICs, unshielded.
Internal wiring?
Humm...
CLIP
=========================================================================
From: StepHydro@aol.com
Subject: Re: [JN] Pariah: farther OT
Date: Wed, 24 Mar 1999 13:52:50 EST
Source: Sound Digest Archive v02.n091
In a message dated 99-03-24 13:35:52 EST, AnnaLogg@aol.com writes:
> > "To wake the soul by tender strokes of art" (Alexander Pope, from his
> > _Prologue to Addison's Cato_) is the most apropo inscription on the
> inside
> > of the cover of the harpsicord at Alice Tully Hall.....
Anna,
my hpschd (for sale :-) lid bears the inscription:
Quantum materiae materietur marmota monax si marmota monax
materiam possit materiari
I get too many challenges to the syntax, so I'm painting it out :-)
Cheers/Carron
=========================================================================
From: SBench@aol.com
Subject: [JN] Part 2 of Voltage Regulator Series
Date: Sun, 20 Feb 2000 20:43:23 EST
Source: Sound Digest Archive v02.n457
Hi All,
Put part 2 of the regulator series on my web page. This one has good
line and load regulation. Only cathode follower degeneration.
Next installment covers error amp stages (2 tube + VR) regulators.
direct access is at
http://members.aol.com/sbench/reg2.html
or via my main page at
http://members.aol.com/sbench101
Best Regards,
Steve
=========================================================================
From: SBench@aol.com
Subject: [JN] Part 4
Date: Mon, 6 Mar 2000 22:32:28 EST
Source: Sound Digest Archive v02.n475
Hi Joes,
Part 4 of the regulator series is now up on my web page. This goes
as far as series regulators will take us. There's a "tweak" for the
example regulator shown in part 3 that provides about 1 milliohm output
resistance, and about 25 microvolts of output ripple using the triode
of the 6BM8 (unused in part 3 circuit).
Direct access to part 4 is at
http://members.aol.com/sbench/reg4.html
or via the "front door" at
http://members.aol.com/sbench101
Part 5 will be shunt regulators (in a couple of weeks).
Best Regards,
Steve
=========================================================================
From: Simon Busbridge <S.C.Busbridge@bton.ac.uk>
Subject: Re: [JN] Part 4
Date: Tue, 7 Mar 2000 07:09:17 +0000 (GMT)
Source: Sound Digest Archive v02.n475
Thanks for all your efforts on this Steve.
Although I have been lurking recently I have much enjoyed your articles.
Simon
PS - can't wait for the one on shunt regulators!
On Mon, 6 Mar 2000 SBench@aol.com wrote:
> Hi Joes,
> Part 4 of the regulator series is now up on my web page. This goes
> as far as series regulators will take us. There's a "tweak" for the
> example regulator shown in part 3 that provides about 1 milliohm output
> resistance, and about 25 microvolts of output ripple using the triode
> of the 6BM8 (unused in part 3 circuit).
>
> Direct access to part 4 is at
> http://members.aol.com/sbench/reg4.html
>
> or via the "front door" at
> http://members.aol.com/sbench101
>
> Part 5 will be shunt regulators (in a couple of weeks).
>
> Best Regards,
> Steve
>
Simon Busbridge, BSc(Hons) PhD CPhys MInstP
School of Engineering
University of Brighton
Lewes Road
Moulsecoomb
Brighton BN2 4GJ
UNITED KINGDOM
Tel: 0044 (0)1273 642542
Fax: 0044 (0)1273 642327/642301
e-mail: s.c.busbridge@bton.ac.uk, scbusbridge@hotmail.com
=========================================================================
From: SBench@aol.com
Subject: [JN] Part 5 Shunt Regulators
Date: Sat, 11 Mar 2000 18:01:11 EST
Source: Sound Digest Archive v02.n479
Hi Joes,
I have not updated the index yet, but part 5 of the regulator
series, covering shunt regulators is up on my web page.
It can be accessed directly via
http://members.aol.com/sbench/reg5.html
or thru any of the previous parts in the series (at the end of the
part, there is a link to the "next" part of the series).
For those coming in late the series addresses tube based voltage regulators
and can be gotten by either the series start
http://members.aol.com/sbench/reg1.html
or via the "front door" at
http://members.aol.com/sbench101
Best Regards,
Steve
=========================================================================
From: Richard C Nevill <rnevill@is.dal.ca>
Subject: Re: [JN] Part 5 Shunt Regulators
Date: Sat, 11 Mar 2000 22:01:11 -0400 (AST)
Source: Sound Digest Archive v02.n479
Steve,
I want to personally thank you for making this series available to all
us joes. For myself as a newbie this was of great help. I now have ahandle
on things that sounded Greek to me.
Cheers and thanks again
Richard Nevill
=========================================================================
From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
Subject: Re: [JN] Part 5 Shunt Regulators
Date: Sun, 12 Mar 2000 03:07:31 +0300
Source: Sound Digest Archive v02.n479
Hats of to good old Bench.........
What a marvellous series of article he has created about regulators.
Absolutely smashing.
It is the best web site in the world.
Any person that wishes to learn about regulated tube circuits , HAS to go to
these pages.
EXCELLENT work , Steve.
All the basics and a few other tricks are there. Simple - with few words and
maths.
And yet very well documented. No loose claims , no religious approach , just
plain good common sense and talented design.
I really admire and respect you , Steve :-)
In my opinion regulated PSU are the toughest art in the tube discipline.
At least it is to me.
Very few seems to master it , and it is one area that one never seems to get
over and done with.
This series made by Steve will bring any one really interested in how good
tubes amplifiers can actually really sing , a lot closer to the goal.
Those of you that might be a little disappointed about the merits of the shunt
regulators compared to series regulators , should know that it is indeed
possible to achieve just as good results with shunt reg. as it is with the
series regulators. But as I have argued so many times in the past , they will
be big as cars.
And sinking huge currents...
It is possible to have Z-outs for both types , in the fraction of a milliOhm -
DC to many 100 kHz's , also for high transients.
But in this quality they certainly sound the same to my ears and all the
persons I have demonstrated them to.
That's why I choose the lighter series regulators , for most circuits.
Thank you Steve for sharing all that precious information with us.
I really regret you live so long away from me. I would LOVE discussing
construction details with you.
I do not think I could learn you anything , but you sure as hell , could learn
me a lot.
It took me years to learn how to build good regulators , the way you do , and I
still learn almost every time I make a new design.
Were you born with all this knowledge ?
Hmm - Maybe you grew up on a technical library...;-)
- - Kurt
=========================================================================
From: SBench@aol.com
Subject: Re: [JN] Part 5 Shunt Regulators
Date: Sun, 12 Mar 2000 22:43:53 EST
Source: Sound Digest Archive v02.n480
In a message dated 00-03-11 21:10:49 EST, kurt-steffensen@teliamail.dk writes:
<<
Those of you that might be a little disappointed about the merits of the
shunt
regulators compared to series regulators , should know that it is indeed
possible to achieve just as good results with shunt reg. as it is with the
series regulators. But as I have argued so many times in the past , they will
be big as cars.
And sinking huge currents...
It is possible to have Z-outs for both types , in the fraction of a milliOhm
- -
DC to many 100 kHz's , also for high transients.
But in this quality they certainly sound the same to my ears and all the
persons I have demonstrated them to.
>>
Hi Joes,
As Kurt noted, shunt regulators chew up a lot of power. Kurt, you're very
right. It IS possible to have low Zout for both devices even over a large
bandwidth.
There may be another factor that is getting in the way. In the quest of
getting the Zout down, perhaps there is a price to pay... If the starting
point is a reasonable impedance, say 100 ohms corresponding to a
gm of 10mS, then to achieve 100 milliohm through feedback techniques
requires a loop gain of 1000. To achieve 1 milliohm using this technique
requires a loop gain of 100,000. Now this is clearly possible. The problem
becomes the large signal transient performance. To achieve a 100kHz
large signal bandwidth implies the open loop gain of said regulator
approaches 100kHz. The closed loop response (using a single pole model,
which isn't accurate, but illustrates the point) implies the system
bandwidth (not closed loop bandwidth) need to be the same 100,000
times higher or (if I did the math right) 10 GHz! Even with multi-pole
compensation techniques, this becomes a fairly tricky problem!
BTW, even though I didn't explicitly spell this out in the series, is why
I opted for somewhat higher output resistances and reasonably simple
compensation techniques.
Notice that there are no large capacitors on the regulators' output!
Also, as I pointed out in the series, there are non-feedback techniques for
improving regulation, even though even these can have some problems
transient wise.
I agree with Kurt's assessment: you can make a "perfect" regulator
on paper, but it is difficult to show that sound is improved.
BTW, for the guitar folks... you may *not* want super regulation in a
guitar amp power supply, as the overload (distortion, attack, crunch,
whatever you choose to call it) may be very bland.
- -.-.-.
Thanks all, for the kind kudos. This project was fun. I ended up using
P-Spice for modeling a lot of the trial topologies I considered. What
was *very* nice was actually getting a reasonable correlation between
the model and real live circuits. That's somewhat gratifying, as the
problem with *only* modeling something is it doesn't account very well
for the large signal issues. At least yet.
A little history. When I was 3 I stuck a bobby pin (remember those?)
into a wall outlet. Changed my future ;-)
Didn't do the wall outlet much good though, according to my parents.
I still remember the incident, but don't remember the thought process of
why I thought that might be a good thing to do 8-]
Best Regards,
Steve
=========================================================================
From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
Subject: Re: [JN] Part 5 Shunt Regulators
Date: Mon, 13 Mar 2000 13:01:22 +0300
Source: Sound Digest Archive v02.n481
SBench@aol.com wrote:
>
> I agree with Kurt's assessment: you can make a "perfect" regulator
> on paper, but it is difficult to show that sound is improved.
Yes. I guess that as long as the Z-out of the regulator is below 1 Ohm DC to
100-200 kHz , also on LF-squares ,
and transients , the goal is met.
A few milliOhm in the entire audio range is certainly possible.
There is a lot more to regulated PSU's , but I would not know where to start or
where to end.
I still learn here. And many fun circuits are yet to be tried.
I do think it is my favourite issue to discuss , though. :-)
BTW , in my previous post , I did not mean a fraction of a milliOhm , but a
fraction af an Ohm.
Though , I personally believes that the best results can be achieved with
regulated PSU's , I am still impressed with how much can be done with plain simple
LC circuits.
> BTW, for the guitar folks... you may *not* want super regulation in a
> guitar amp power supply, as the overload (distortion, attack, crunch,
> whatever you choose to call it) may be very bland.
Ha - ha..... Yes , that is very true , Steve ;-)
One of the distortion spectra's of the guitar amp , is due to the low regulation
of the PSU.
It acts as a kind of compressor as well.
- - Kurt
=========================================================================
From: Simon Busbridge <S.C.Busbridge@bton.ac.uk>
Subject: [JN] Part for Tandberg 9100x
Date: Tue, 30 Nov 1999 07:34:13 +0000 (GMT)
Source: Sound Digest Archive v02.n348
Hi Folks,
Would anyone be able to point me in the right direction to look for
Tandberg reel to reel spares?
TIA
Simon
Simon Busbridge, BSc(Hons) PhD CPhys MInstP
School of Engineering
University of Brighton
Lewes Road
Moulsecoomb
Brighton BN2 4GJ
UNITED KINGDOM
Tel: 0044 (0)1273 642542
Fax: 0044 (0)1273 642327/642301
e-mail: s.c.busbridge@bton.ac.uk, scbusbridge@hotmail.com
=========================================================================
From: rcjones1@mmm.com
Subject: [JN] Partial fix on SE amp
Date: Thu, 14 Jun 2001 07:45:09 -0500
Source: Sound Digest Archive v02.n909
Well last night I kinda fixed it. It appears that those 6BQ5's were
oscillating so much that they were drawing a lot of current. I put a
100ohm resistor on the plate pin and that helped a bit. Next I will put
more 100ohm resistors on each of the pins till it stops. It is an
oscillation because depending on the physical locations of the tubes
changes its plate voltage - very strange.
I went to RS and bought a bag of those misc. resistors. I decided to use
those until I have all the values correct, then I'll buy rikens. It plays
music. Very dynamic and airy. Highs are still a little wiry, maybe from
the 6BQ5's instability and the fact my 5842's are not broken in.
The 5842's are spot on for specs... 150v, 2.1v bias, 16mA. YES!!!
6BQ5's sometimes are: 200v, 45mA.
Well anymore thoughts on taming a 6BQ5? Anything I should be aware of.
They are in triode mode. The screen is tied before the 100ohm plate
resistor. Should I tie the screen directly to the plate, or does this not
matter? The only other one that needs a 100ohm resistor is g1.
Thanks for all your help! Does anyone recommend a new 6BQ5? Thanks!
Richard
=========================================================================
From: "Danielak, Robert M" <robert.m.danielak@lmco.com>
Subject: RE: [JN] partial-range output transformers
Date: Mon, 27 Mar 2000 09:41:14 -0500
Source: Sound Digest Archive v02.n498
try the hammond 125D or 125E.
if you keep <100Hz out of them the sound even better...
bob.d.
> ----------
> From: John Hancock[SMTP:John_Hancock@swissre.com]
> Sent: Monday, March 27, 2000 4:00 AM
> To: sound@lists.io.com
> Subject: [JN] partial-range output transformers
>
> Dave Slagle wrote:
>
> >if we must have the same sonic signature... build the same exact amps
> with
> >the same everything including cores for the output... only wind one with
> >inductance being the goal, and optimise the other for winding
> >capacitences... i would think the signature would be similar.
>
> Does anyone know of a commercially available SE output transformer
> designed
> specifically for midrange on up? I have personally never seen such an
> animal, but would like to get a few.
>
> John
>
>
=========================================================================
From: "John Hancock" <John_Hancock@swissre.com>
Subject: [JN] partial-range output transformers
Date: Mon, 27 Mar 2000 10:00:28 +0100
Source: Sound Digest Archive v02.n498
Dave Slagle wrote:
>if we must have the same sonic signature... build the same exact amps with
>the same everything including cores for the output... only wind one with
>inductance being the goal, and optimise the other for winding
>capacitences... i would think the signature would be similar.
Does anyone know of a commercially available SE output transformer designed
specifically for midrange on up? I have personally never seen such an
animal, but would like to get a few.
John
=========================================================================
From: "Dale Simon-contr" <Dale.Simon-contr@trw.com>
Subject: [JN] part id help
Date: Fri, 15 Jun 2001 10:07:28 -0400
Source: Sound Digest Archive v02.n911
Hi all,
I just pulled a couple of parts from a piece of industrial scrap.
Siemens capacitor B25838-J6105-K001 MKV 1uF +/- 10%, Un 900V, Ueff 640V
(I'm guessing oil filled motor start cap.)
Arcol resistor 95.50, HS50, 22R F
(Big resistor is all I know)
Any use for a amp power supply?
Thanks,
Dale
=========================================================================
From: Chris and Susan Beck <n9zes@execpc.com>
Subject: [JN] Part II of "Tubes in the Oddest Places"
Date: Sat, 01 Jul 2000 20:05:43 -0500
Source: Sound Digest Archive v02.n594
Hi, gang.
Just spent the afternoon wiring up the tube photocontrol a fellow
streetlight collector sent me. It was manufactured in November 1957,
and all the tubes are early 60's vintage, so they were replaced at one
time. I have another control, 1961 vintage with the original tubes, but
it's not in nearly as nice shape.
I wired it so I can plug in into an outlet, and then plug the device to
be controlled into the outlet on the board. It works perfectly! I am
hesitant to mount it permanently outside as it's in far too nice of
shape. I'll tinker with it for a while and then mount it up with the
rest of my collection of streetlighting goodies.
It's safe to say this control has seen 35 to 40 years of use, sitting on
a pole outside in the weather. Granted, it is sealed up in it's glass
jar, but I think that's pretty impressive. I don't have a schematic of
the circuit drawn out, but it's very simple. There are 2 caps, a few
resistors, a transformer, a pot to set the turn-on light level, 2
relays, and the 3 tubes. That's about it. I use it to control the 50's
vintage "gumball" fixture in my back yard. I haven't wired it
permanently yet, so it's just a green extension cord to run the 40 feet
or so.
So, it's not exactly audio related, but I find it fascinating the uses
that tubes saw many years ago.
Stop by my web page and see my fixture outside and pics of the
photocontrol.
Fixture: http://www.execpc.com/~n9zes/streetlights/streetlights2.html
Photocontrol: http://www.execpc.com/~n9zes/streetlights/tubepc.html
Have a nice weekend!
Chris
=========================================================================
From: "Miglioranza, Richard (Sudbury)" <RMiglioranza@inco.com>
Subject: [JN] parts for sale
Date: Thu, 8 Mar 2001 12:15:26 -0500
Source: Sound Digest Archive v02.n829
Thought I'd list some parts here before listing on ebay.
one pair of Bartolucci potted chokes-20H@50mA $100
4-GE poly. and oil can caps-45uf@500vac (round style) $60
4-GE poly. and oil can caps-120uf@220vac (round style) $60
2-Mallory poly. and oil can caps-60uf@370vac (round style) $30
2-Copper chassis' 13"x9"x2.5" approx. 1/16" thick, ordered for a project but
never used, these are seemless but are unfinished. $180 for pair.
Prices do not include shipping.
Thanks,
Ritchie
=========================================================================
From: michael knapp <sound@auriculum.com>
Subject: RE: [JN] parts in BA (was: OPTs for 2A3 amp...)
Date: Sun, 29 Jul 2001 10:36:27 -0700
Source: Sound Digest Archive v02.n935
> >
> >By the way, does anyone know of a source for motor-run caps? I need two of
> >them; about 25uf @500v. Jeremy suggested old air conditioners, but I only
> >have a beat-up old window unit that I'm not able to replace yet. I'm a
> >little afraid to any midnight investigation of my neighbors' units as they
> >all have big dogs... If anyone knows where I can find these things, please
> >let me know
oh goodness. this might inspire a little ire...
for the past two years i have had a "houseguest" that has filled my barn
and yard with junk (i live in a barn. in oakland california. yes, we have
barns in oakland. well, one anyway...) mostly, various flavors of
industrial detritus. for the past two years, i have been bugging him to
get rid of it, and finally, after conspiring with his family and
threatening to burn all his stuff, he's starting to clear out with a
vengeance. in the past two days we've scrapped about 6000# of stuff. a
lot of it old lab instruments w/ high voltage transformers, oil caps, tube
sockets, coils, etc. i'm trying to set a good example, so i've been
refraining from salvaging parts from these things (even though i've gazed
lustfully upon them). but, there is more stuff to get rid of. i also
have a bunch of tube tuners (mainly mono stuff), an altec SS amp, a B&K amp
that needs work (good toroid LV tranny and chassis/faceplate), basically
lots of stuff that some of you might be interested in. also a pair of
altec valencias, and a thorens 124.
here's the deal: i'm not going to ship any of it. i'm not going to pull
any of the parts myself. i'm still not sure what all we'll find that would
be useful (a lot of its been scrapped already). but, if you are in the bay
area, feel like coming over and taking some equipment (no taking the
goodies and leaving the carcass, unless its really big) and dropping a few
bucks in a hat (or not, depending on the piece), contact me off list
<mk-sound@auriculum.com>. the thorens and altecs will not be so cheap.
i can't even promise that there's much good stuff left, but it just struck
me that i should at least offer it to people who might be able to use
it. if there's no interest, its getting scrapped but quick.
my apologies to those of who you aren't local and consider this spam.
mike
=========================================================================
From: Jeremy Epstein <jepstein@shwd.com>
Subject: [JN] Parts purchase coop started
Date: Tue, 08 Feb 2000 11:52:30 -0500
Source: Sound Digest Archive v02.n439
As we all know, parts suitable for use in vacuum tube gear are not
always easily available cheaply. Some guitar amp builders on the AMPAGE
BBS have decided to do something about this and are forming a purchasing
coop - a resistor kit was the first group buy and there are other parts
being discussed now.
Check www.ampage.org/coop/ for more information. You are probably in
time to give input into future purchases as well.
- -j
- --
=========================================
Jeremy Epstein .........jepstein@shwd.com
=========================================
=========================================================================
From: Robert C Chambers <rchamber@norwich.edu>
Subject: Re: [JN] Parts source in EU
Date: Fri, 8 Dec 2000 10:22:22 -0500 (EST)
Source: Sound Digest Archive v02.n755
Hello David-
Try: http://www.triodes.nl
Regards,
Robert
=========================================================================
From: David Home <David_Home@creoscitex.com>
Subject: [JN] Parts source in EU
Date: Fri, 8 Dec 2000 15:17:43 +0100
Source: Sound Digest Archive v02.n755
Hello all.
I am new to Europe. I have searched on the net and cannot seem to find a parts dealer in the EU that
carries the type of parts our type use.
With all the DIY going on in many European countries, you guys must be getting the parts from somewh
ere!
I am used to the vast selection of Michael Percy and Welborne Labs.
I want decent resistors ( Holco, Beyschlag, Tantalum film, etc), caps ( SCR, AN, BG, etc), and other
tidbits.
Anyone give me a lead?
Regards, David
=========================================================================
From: "Dusan Kanduc" <joelist@email.si>
Subject: Re: [JN] Parts source in EU
Date: Fri, 8 Dec 2000 18:16:10 +0100
Source: Sound Digest Archive v02.n755
David,
Take a look at this (mostly Italian) sites:
http://www.audiokit.it/
http://www.audiolamp.com/
http://www.audio-note.com/ (French site)
http://www.borbelyaudio.com/
http://www4.topnet.it/vintagehifi/index.html
I hope this helps
Regards
Dusan Kanduc
- ----- Original Message -----
From: David Home <David_Home@creoscitex.com>
To: Sound (E-mail) <sound@lists.io.com>
Sent: Friday, December 08, 2000 3:17 PM
Subject: [JN] Parts source in EU
> Hello all.
> I am new to Europe. I have searched on the net and cannot seem to find a
parts dealer in the EU that carries the type of parts our type use.
> With all the DIY going on in many European countries, you guys must be
getting the parts from somewhere!
> I am used to the vast selection of Michael Percy and Welborne Labs.
> I want decent resistors ( Holco, Beyschlag, Tantalum film, etc), caps
SCR, AN, BG, etc), and other tidbits.
> Anyone give me a lead?
> Regards, David
>
>
=========================================================================
From: Steven Bird <Steven-Bird@utc.edu>
Subject: [JN] PAS 3X mods
Date: Fri, 07 May 1999 12:11:47 -0400
Source: Sound Digest Archive v02.n137
Hello to all Joes,
I'm new to the list, so I have an informational question first.
I have a PAS3X Dynaco pre-amp, which I've upgraded in several ways; I've
replaced resistors and caps, significantly upgraded the power supply
(including putting it in a seperate chassis), and built an outboard
regulated DC filament supply. The improvements have been excellent so far.
Now I'm interested in bypassing the tone controls and the "seperation"
rotary switch, replacing and/or simplifying the rotary switches for source
selection, and quieting some hum in the phono section. Can anyone direct
me to a website(s) which has discussions about these matters?
Thanks for your help,
Steve
- ----------------------------------------
Dr. Steven Bird
Director of Orchestras
University of Tennessee at Chattanooga
=========================================================================
From: "Phil Sieg" <psieg@nxs.net>
Subject: Re: [JN] PAS 3X mods
Date: Sat, 8 May 1999 19:35:06 -0400
Source: Sound Digest Archive v02.n138
Steve,
I'm just up the road in Knoxville and we come to Chattanooga regularly to
visit family. I've got the Last PAS (David Voorhis) articles from AA in
the early '80s and Brian Clark's PAS Mod manual. I rebuilt a PAS 3 at that
time which was a combo of the two mods. Stripped of all functions save
phono w/dual mono volume controls and a mute switch for each channel. I
don't have the unit anymore, but I remember it as a first-rate phono
preamp - as good as most of what was out there at the time. One drawback -
the circuit as given does not have the gain for MC, only MM. Also, it would
be easy to include a function switch, if you want phono and CD. Be happy
to make copies for you and we can arrange a get together when my wife and I
come to Chattanooga.
Best regards,
Phil Sieg
5332 Buckhead Trail
Knoxville, Tennessee 37919
423 330.0198
423 584.5063 (fax)
- ----- Original Message -----
From: Steven Bird <Steven-Bird@utc.edu>
To: <sound@lists.io.com>
Sent: 07 May, 1999 12.11
Subject: [JN] PAS 3X mods
> Hello to all Joes,
>
> I'm new to the list, so I have an informational question first.
>
> I have a PAS3X Dynaco pre-amp, which I've upgraded in several ways; I've
> replaced resistors and caps, significantly upgraded the power supply
> (including putting it in a seperate chassis), and built an outboard
> regulated DC filament supply. The improvements have been excellent so
far.
>
> Now I'm interested in bypassing the tone controls and the "seperation"
> rotary switch, replacing and/or simplifying the rotary switches for source
> selection, and quieting some hum in the phono section. Can anyone direct
> me to a website(s) which has discussions about these matters?
>
> Thanks for your help,
>
>
> Steve
>
>
>
>
> ----------------------------------------
> Dr. Steven Bird
> Director of Orchestras
> University of Tennessee at Chattanooga
=========================================================================
From: Eric Weitzman <eweitzman@acm.org>
Subject: RE: [JN] PAS 3X mods
Date: Thu, 13 May 1999 07:17:10 -0700
Source: Sound Digest Archive v02.n142
I've replied to this message twice and not seen my message on the list. It
contained 4 attachements. Does anyone know if there's a limit to the size
of message that can be posted?
Steve: did you get my responses that were sent directly to you?
- - Eric
- -----Original Message-----
From: Steven Bird [SMTP:Steven-Bird@utc.edu]
Sent: Friday, May 07, 1999 9:12 AM
To: sound@lists.io.com
Subject: [JN] PAS 3X mods
Hello to all Joes,
I'm new to the list, so I have an informational question first.
I have a PAS3X Dynaco pre-amp, which I've upgraded in several ways; I've
replaced resistors and caps, significantly upgraded the power supply
(including putting it in a seperate chassis), and built an outboard
regulated DC filament supply. The improvements have been excellent so far.
Now I'm interested in bypassing the tone controls and the "seperation"
rotary switch, replacing and/or simplifying the rotary switches for source
selection, and quieting some hum in the phono section. Can anyone direct
me to a website(s) which has discussions about these matters?
Thanks for your help,
Steve
- ----------------------------------------
Dr. Steven Bird
Director of Orchestras
University of Tennessee at Chattanooga
=========================================================================
From: "Ron Blaschke" <blascrw@hotmail.com>
Subject: [JN] Pase Linear (Sorry)
Date: Wed, 01 Dec 1999 13:40:06 GMT
Source: Sound Digest Archive v02.n350
Sorry clicked the wrong address in the address book.
Ron
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
=========================================================================
From: Tim Reese <tgrmail@nmr.MGH.harvard.EDU>
Subject: [JN] RE: PAS question
Date: Sat, 8 May 1999 18:40:52 -0400 (EDT)
Source: Sound Digest Archive v02.n138
Steven wrote
>Hello to all Joes,
>
>I'm new to the list, so I have an informational question first.
>
>I have a PAS3X Dynaco pre-amp, which I've upgraded in several ways; I've
>replaced resistors and caps, significantly upgraded the power supply
>(including putting it in a seperate chassis), and built an outboard
>regulated DC filament supply. The improvements have been excellent so far.
>
>Now I'm interested in bypassing the tone controls and the "seperation"
>rotary switch, replacing and/or simplifying the rotary switches for source
>selection, and quieting some hum in the phono section. Can anyone direct
>me to a website(s) which has discussions about these matters?
>
>Thanks for your help,
>
>
>Steve
>
>
>
>
>----------------------------------------
>Dr. Steven Bird
>Director of Orchestras
>University of Tennessee at Chattanooga
>
I've a PAS-2 that has the complete Curcio board set... I've never listened
to the unmodded PAS, since mine was a nonfunctional junker before I added
the Curcio boards a few years back.
A couple of suggestions - I think the best known circuit mods are due to
Norm Koren, and were published in Glass Audio. I can dig up the issues and
send references/copies, or you could buy the back issues.
A couple of suggestions - a search of www.dejanews.com (select power search,
limit the search to rec.audio.tubes, keywords Dynaco PAS) gave several
articles specifically dealing with PAS mods and PAS humming. Look at
the "Dynaco PAS-3 suggestions" and "Help my PAS is humming" threads.
With your new power supply, look to see if the filament supply is floating
(which will hum) or if there are ground loops in the preamp-amp connection,
or look for floating grounds in your signal connections. There won't be
an induced hum problem since separating the pre and PS will stop any
inductive or capacitive coupling between PS and signal circuits. I presume
you added a lot of B+ filtering to this new PS, so the hum likely does not
come from the B+.
I don't know specifically how to bypass the tone controls, but the complete
PAS manual is in PDF format at http://www.curcioaudio.com/dynadr_3.htm
and I believe you can figure it out, or Norm covers it. Bypassing the
tone controls is common, although most people seem to leave the selector
and RCA jacks alone. Replacing the volume and balance controls might
be helpful.
Elsewise you can always post to rec.audio.tubes where most of the discussion
of vintage components happens.
hth tr
- ----------------------------------------------------------------------
Tim Reese, MGH NMR Center reese@nmr.MGH.harvard.edu
=========================================================================
From: "Ian McPhail" <i.mcphail@rmit.EDU.AU>
Subject: [JN] Pass A40 update?
Date: Wed, 12 Apr 2000 11:21:50 +1000
Source: Sound Digest Archive v02.n517
Joesters, has there been an upgrade to the Pass A40 amp by
Thagard (not the A75) in a recent Audio Electronics (formerly Audio
Amateur), would love to get a copy of the article if so.
regards Ian
Ian McPhail i.mcphail@rmit.edu.au
RMIT Chem and Met Eng Dept 110
GPO Box 2476V
Melbourne 3001
Australia
tel +61 3 9925 2408
tel +61 3 9925 3326
fax +61 3 9925 3746
=========================================================================
From: "Ian McPhail" <i.mcphail@rmit.EDU.AU>
Subject: [JN] Pass A40 update
Date: Thu, 13 Apr 2000 09:52:33 +1000
Source: Sound Digest Archive v02.n518
Joesters, can anybody dig up a copy of the following article from
Sept 99 (vol 30 no.5) of Audio Electronics (Audio Amateur)?
I/m after
"A Case Study in Audio Amplifier Design The A40M part 1" by
Norman Thagard and any subsequent parts
on upgrades to the Pass A40.
regards Ian
Ian McPhail i.mcphail@rmit.edu.au
RMIT Chem and Met Eng Dept 110
GPO Box 2476V
Melbourne 3001
Australia
tel +61 3 9925 2408
tel +61 3 9925 3326
fax +61 3 9925 3746
=========================================================================
From: "Aigner Josef, Dr." <j.aigner@staedtische.co.at>
Subject: [JN] Pass Element 6AU5GA
Date: Sat, 12 Aug 2000 20:08:34 +0200
Source: Sound Digest Archive v02.n625
Hi Joes,
currently i am working on an phono-line preamp, a more or less close
relative of thomas mayer's vinyl savor. i want to use a series voltage
regulation -( i know shame on me, to save the last bit of my reputation and
to support my energy supplier, i use tubes). so my question to the
community:
as pass element i want to use a triode connected 6AU5GA. what points do i
have to observe.......
Thanks in advance,
Josef
=========================================================================
From: Steve Van Osdell <svanos@queencity.com>
Subject: [JN] Passenger of 4th Airline attached Terrorists!
Date: Wed, 12 Sep 2001 03:02:37 -0400
Source: Sound Digest Archive v02.n964
It seems that there is evidence coming out that the passengers (or some
of them) on the flight that crashed in Pennsylvania decided to attack
the terrorists. This is what one passenger told his wife on cell
phone. For details, see this link (and YES, I DO read FreeRepublic and
proud of it!)
http://www.freerepublic.com/forum/a3b9ef7af3eba.htm
=========================================================================
From: Phil <tube@jump.net>
Subject: Re: [JN] Passenger of 4th Airline attached Terrorists!
Date: Wed, 12 Sep 2001 04:04:40 -0500
Source: Sound Digest Archive v02.n964
That's the only thing that makes sense. Once I heard that the terrorists
told
people to call family because they were going to die, I at first wondered
why
all of them didn't attack, giving themselves at least a small chance. But
judging
people without walking in their shoes is not fair, and in some cases there
were
perhaps four armed, trained fighters guarding the aisles, and when first
faced
with impending death, it can be fairly normal to succumb to fear. However,
it did immediately explain why the fourth jet went down; it almost had to
be
because the passengers *did* attack them! They didn't save themselves, but
they tried, and they saved god only knows how many other people. Wow!
Thanks for the link!
Phil
Steve Van Osdell wrote:
> It seems that there is evidence coming out that the passengers (or some
> of them) on the flight that crashed in Pennsylvania decided to attack
> the terrorists. This is what one passenger told his wife on cell
> phone. For details, see this link (and YES, I DO read FreeRepublic and
> proud of it!)
>
> http://www.freerepublic.com/forum/a3b9ef7af3eba.htm
=========================================================================
From: "Chris Vryonides" <chrisvryonides@hotmail.com>
Subject: Re: [JN] Passenger of 4th Airline attached Terrorists!
Date: Wed, 12 Sep 2001 09:53:00 +0000
Source: Sound Digest Archive v02.n964
Who can honestly say how they would have reacted under such stress; what
seems like good ol' fashioned commonsense to us on the ground translates to
good ol' fashioned heroism at the scene, unquestionably.
The polar opposite of the terrorist actions - logical people cooly accepting
their fate, and sacrificing themselves to help save perhaps thousands -
courage and humanity from which we might take some meagre comfort as we
attempt to make sense of what happened.
To our stateside friends, our prayers and hopes,
Chris
- ----Original Message Follows----
From: Phil <tube@jump.net>
To: Steve Van Osdell <svanos@queencity.com>
CC: Joe List <sound@lists.io.com>
Subject: Re: [JN] Passenger of 4th Airline attached Terrorists!
Date: Wed, 12 Sep 2001 04:04:40 -0500
That's the only thing that makes sense. Once I heard that the terrorists
told
people to call family because they were going to die, I at first wondered
why
all of them didn't attack, giving themselves at least a small chance. But
judging
people without walking in their shoes is not fair, and in some cases there
were
perhaps four armed, trained fighters guarding the aisles, and when first
faced
with impending death, it can be fairly normal to succumb to fear. However,
it did immediately explain why the fourth jet went down; it almost had to
be
because the passengers *did* attack them! They didn't save themselves, but
they tried, and they saved god only knows how many other people. Wow!
Thanks for the link!
Phil
Steve Van Osdell wrote:
> It seems that there is evidence coming out that the passengers (or some
> of them) on the flight that crashed in Pennsylvania decided to attack
> the terrorists. This is what one passenger told his wife on cell
> phone. For details, see this link (and YES, I DO read FreeRepublic and
> proud of it!)
>
> http://www.freerepublic.com/forum/a3b9ef7af3eba.htm
_________________________________________________________________
Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp
=========================================================================
From: "Hugh R. Dean" <aksa1@optushome.com.au>
Subject: [JN] Passion
Date: Sat, 16 Sep 2000 10:19:45 +1000
Source: Sound Digest Archive v02.n664
Hi Nick,
I have been browsing your excellent website and reading your articles.
I particularly like your written style; that is, aside from your drivers,
which of course I have not yet heard.
I note with amusement we come from the same town - Melbourne, I believe?
It seems to me you have exemplary designs, an honest but passionate
approach, and a strong determination to give VALUE FOR MONEY!!!
Here's hoping a top flight company is successful.
Cheers,
Hugh R. Dean
Research Director
www.printedelectronics.com
Melbourne, Australia
=========================================================================
From: Allen Wright <AllenVSE@compuserve.com>
Subject: [JN] Passive Attenuator Interconnect
Date: Sat, 26 Aug 2000 08:22:04 -0400
Source: Sound Digest Archive v02.n642
Tony sez:
>>>I was using Kimber PBJ for the longest time on the preamp output. The
sound had a very lush midrange...Then I braided (a la Kimber) a solid,
cotton insulated 32 AWG cable. Completely different sound. There is a big
hole in the midrange, lushness is gone. But the highs - they extend all the
way up<<<
From a 15k ohm source, minimising the capacitance of the cable is vital for
the highs,and the i/c you made up from thin wire I would expect to have
much less capacitance than the Kimber. And as the wire is much thinner I
would expect it to sound much "clearer" as well.
The losses you mention almost certainly come from the braiding being too
"loose", and perhaps from the cotton dielectric.
Try using wire wrap wire and braiding it REALLY tightly. or encasing it in
a KYNAR or teflon heatshrink to get the wires absolutely held in place.
Our silver foil interconnects took a major step forward when we started
using a double sided adhesive tape as the seperator between the foils -
certainly not as good a dielectic as the teflon strip used before, but the
fact that the foils cannot move anywhere near as much in response to the
signal's fields seems to be a bigger improvement than the disadvantage of a
lesser dielecteric.
Allen (VSE)
=========================================================================
From: "Tony Bombera" <tbombera@pathcom.com>
Subject: [JN] Passive Attenuator Interconnect - Was More CD mods
Date: Fri, 25 Aug 2000 17:52:34 -0400
Source: Sound Digest Archive v02.n642
Hi Joes,
I am using a 15kOhm passive "preamp". The output therefore looks like a
Loesch preamp output.
I was using Kimber PBJ for the longest time on the preamp output. The sound
had a very lush midrange. But I observed that
when my SE amp was using especially Globe 45, there was not too much high
end.
Then I braided (a la Kimber) a solid, cotton insulated 32 AWG cable.
Completely different sound. There is a big hole
in the midrange, lushness is gone. But the highs - they extend all the way
up.
What are your experiences with interconnects with passive or Loesch style
preamps?
Regards,
Tony Bombera
=========================================================================
From: rcjones1@mmm.com
Subject: Re: [JN] passive CD player output (subject for last mail)
Date: Tue, 4 Sep 2001 07:51:10 -0500
Source: Sound Digest Archive v02.n960
$)C
If that is a voltage output DAC then its easy. Just connect a capacitor
from the output pin to the output RCA jack. Value is dependent on the
following stages input impedance. I tried it in my Denon CD-Player and
seems to work. I think I used a 10uf Solen bypassed with a MIT RTX
Multi-Cap.
Richard
Bjorn Kolbrek
<bjornk@studpor To: sound@lists.io.com
s.hit.no> cc: (bcc: Richard - BIE C. Jones/US-Corporate/3M/US)
Subject: Re: [JN] passive CD player output (subject for
last mail)
09/04/01 03:22
AM
$)C
At 09:45 04.09.01 +0200, you wrote:
>Hi Joes,
>
>A friend of mine wants to modify his Technics SL-PG460A, and are thinking
>about using a passive filter at the output of the dac (without any further
>components in the signal path). Does anybody got some tips on how to do
>this, component values etc.?
>
>regards, Bj)*rn
- -------------------------------------------------
__/\__
/ ____ \ Bj)*rn Kolbrek
| | || | |
| | || | | bjornk@studpors.hit.no
| | || | | http://www.geocities.com/la1zka
| | || | |
| |____| |
| /||||\ |
--------
| | | |
- -------------------------------------------------
=========================================================================
From: Bjorn Kolbrek <bjornk@studpors.hit.no>
Subject: Re: [JN] passive CD player output (subject for last mail)
Date: Tue, 04 Sep 2001 10:22:25 +0200
Source: Sound Digest Archive v02.n960
At 09:45 04.09.01 +0200, you wrote:
>Hi Joes,
>
>A friend of mine wants to modify his Technics SL-PG460A, and are thinking
>about using a passive filter at the output of the dac (without any further
>components in the signal path). Does anybody got some tips on how to do
>this, component values etc.?
>
>regards, Bjørn
- -------------------------------------------------
__/\__
/ ____ \ Bjørn Kolbrek
| | || | |
| | || | | bjornk@studpors.hit.no
| | || | | http://www.geocities.com/la1zka
| | || | |
| |____| |
| /||||\ |
--------
| | | |
- -------------------------------------------------
=========================================================================
From: Bjorn Kolbrek <bjornk@studpors.hit.no>
Subject: Re: [JN] passive filter for CD player, feedback
Date: Fri, 07 Sep 2001 09:27:14 +0200
Source: Sound Digest Archive v02.n961
Hello joes!
Just a little feedback on how the passive analog stage worked out. We used
the filter from the TNT convertus, and my friend commented:
"It's a whole other world! I don't understand why the manufacturer doesen't
do it that way, it's both cheaper and much better!"
A really big upgrade!
Regards, Bjørn
- -------------------------------------------------
__/\__
/ ____ \ Bjørn Kolbrek
| | || | |
| | || | | bjornk@studpors.hit.no
| | || | | http://www.geocities.com/la1zka
| | || | |
| |____| |
| /||||\ |
--------
| | | |
- -------------------------------------------------
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] passive filter for CD player, feedback
Date: Sun, 09 Sep 2001 21:40:55 +0200
Source: Sound Digest Archive v02.n961
At 09:27 7-9-01 +0200, Bjorn Kolbrek wrote:
>Hello joes!
>
>Just a little feedback on how the passive analog stage worked out. We used
>the filter from the TNT convertus, and my friend commented:
>"It's a whole other world! I don't understand why the manufacturer doesen't
>do it that way, it's both cheaper and much better!"
Sure is
It is probably not the way the engineers have been taught......
>A really big upgrade!
value for money ! Did you listen to various types of capacitors ?
Guido
>Regards, Bjørn
>
>-------------------------------------------------
> __/\__
> / ____ \ Bjørn Kolbrek
> | | || | |
> | | || | | bjornk@studpors.hit.no
> | | || | | http://www.geocities.com/la1zka
> | | || | |
> | |____| |
> | /||||\ |
> --------
> | | | |
>-------------------------------------------------
=========================================================================
From: Christian Rintelen <christian@rintelen.ch>
Subject: [JN] Passive highpass know-how?
Date: Sun, 17 Sep 2000 22:42:07 +0200
Source: Sound Digest Archive v02.n665
Dies ist eine mehrteilige Nachricht im MIME-Format.
- --------------A0D4BCAC1430DCCF1605133B
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Content-Transfer-Encoding: 7bit
Joes,
how do I calculate passive 10k highpass 2nd order that sits between the
input transformer and the grid of the tube in a (tweeter) spud amp?? I
know the formula for a 12 dB passive x-over where the R is known
(speaker Z) - but what R do I calculate with when the load is the grid
stopper and the grid of the tube??
(FWIW: Input trannie is a Lundahl LL 7902, tube is a 6C45, auto bias
with unbypassed cathode R. So far I have used an RC between transformer
and grid with 2.7 nF in series and 4k7R parallel with the grid connected
after the C. But the 6 dB slope is not steep enough; the Fostex horn
tweeter cuts in too early.)
TIA for advice!
Christian
- --------------A0D4BCAC1430DCCF1605133B
Content-Type: text/x-vcard; charset=us-ascii;
name="christian.vcf"
Content-Transfer-Encoding: 7bit
Content-Description: Visitenkarte fŸr Christian Rintelen
Content-Disposition: attachment;
filename="christian.vcf"
begin:vcard
n:Rintelen;Christian
tel;fax:01 420 11 57
tel;work:01 420 11 55
x-mozilla-html:TRUE
adr:;;;;;;
version:2.1
email;internet:christian@rintelen.ch
x-mozilla-cpt:;3
fn:Christian Rintelen
end:vcard
- --------------A0D4BCAC1430DCCF1605133B--
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] Passive highpass know-how?
Date: Sun, 17 Sep 2000 23:58:14 +0200
Source: Sound Digest Archive v02.n665
Christian
You need to know:
1 - source impedance
2 - load impedance
1 may be a preamp, say 1 k-ohm
2 is a griod and may rise up to 1 M-ohm
Now a second order network needs to be made, series caps, resistors to ground
Thes ground resistors shall have a ratio of at least 10, compared to each
other. I propose (assumed that the source is 1 k-ohm)
series cap - 10 k-ohm to ground - series cap - 100 k to ground - grid
so far
=
Guido
At 22:42 17/09/2000 +0200, Christian Rintelen wrote:
>Joes,
>
>how do I calculate passive 10k highpass 2nd order that sits between the
>input transformer and the grid of the tube in a (tweeter) spud amp?? I
>know the formula for a 12 dB passive x-over where the R is known
>(speaker Z) - but what R do I calculate with when the load is the grid
>stopper and the grid of the tube??
>
>(FWIW: Input trannie is a Lundahl LL 7902, tube is a 6C45, auto bias
>with unbypassed cathode R. So far I have used an RC between transformer
>and grid with 2.7 nF in series and 4k7R parallel with the grid connected
>after the C. But the 6 dB slope is not steep enough; the Fostex horn
>tweeter cuts in too early.)
>
>TIA for advice!
>
>Christian
>
>Attachment Converted: "C:\PROGRAM FILES\EUDORA\Attach\christian3.vcf"
>
=========================================================================
From: "T. Loesch" <ezee_e@hotmail.com>
Subject: Re: [JN] Passive highpass know-how?
Date: Mon, 18 Sep 2000 09:32:53 GMT
Source: Sound Digest Archive v02.n666
Christian,
If you need a steeper slope the best solution is to go LCR. The Formulas to
calculate these are the same as for any passive crossover. Steinmusic in
germany sells affordable audio chokes, adjustable between 56 and 82mH (or
wider if you take windings off the core). These should do splendidly.
So basically look for the Resistor needed for your Crossover frequency with
(say) 56mH and then the capacitor, using the bog standard textbook
equations. Voila.
Later T
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=========================================================================
From: Eric Weitzman <eweitzman@acm.org>
Subject: [JN] passive linestage experience
Date: Sat, 15 Jan 2000 22:26:24 -0800
Source: Sound Digest Archive v02.n405
So after finally learning the evils of NFB first hand, I decided to make
the last amplification stages in my PAS2 switchable. Switch on -
PAS2. Switch off - passive attenator. Using a 4-pole 2-gang rotary
switch, I can take the amplifier out of the circuit and keep the power
off, which just leaves the source switching and attenuator. I can also
turn the power on and use the phono preamp without the other amp stages.
When I rebuilt the PAS a few years ago I put in a small black Alps
pot. With the linestage out of the circuit, the first thing that I
noticed was how loud the wiper noise from the pot was. The noise went
away when using the amp stage. I don't understand why this should be,
but decided to dump the Alps. But the sound was more detailed than with
the PAS linestage. I've heard you all slamming the PAS2 linestage with
it's high-gain 12AX7s and NFB, now I believe too.
I built a stereo ladder attenuator kit from Michael Percy. I considered
the newer SMD series attenuators, but decided against the noise of the
low-wattage resistors, what with so many of 'em in the circuit. The kit
uses an older model Elma switch and Holco H4 1/2 watt resistors.
When I first listened to the ladder attenuator, I was appalled. Did I
really spend almost 200 bucks and a back-breaking evening of precision
cutting and soldering for this stark, harsh, soul-less sound? The PAS2
was much more musical, maybe it was the Alps, just as Fred Volz
described in November when comparing an Alps pot with some resistors --
From: "Fred Volz" <fcv@emotiveaudio.com>
> But the real disappointment for us was that none of these options sounded as
> good as the Alps pot. They weren't even close. All of the fixed resistors
> sounded etched compared to the pot. Our final conclusion was that the
> resistors made things SEEM more detailed. But, we weren't really hearing any
> more information--maybe even less. Rather, it seemed that the resistors
> added emphasis to the leading edges of sounds. This results in what I (and
> probably others) call an increase in perceived detail--but not REAL
> detail/more information. This was the exact opposite of what I expected to
> find.
Then I remembered -- it takes time to break in components, no? Take your
pick, a couple of hours, 100 hours, whatever it takes to take the edge
off of a resistor, multiply that 24 times for each step of a 24-step
attenuator. So I knocked a few db off of the high end in my crossovers
and lived with the hardened sound.
A while ago, I restored the crossovers to they way they were, and with
my whiz-bang switchable linestage gizmo, I've done some careful
listening.
The passive attenuator has much more detail:
- - abrasive finger noises on basses are startlingly real
- - pitch of the skins on drums can be clearly heard
- - the rattling of the bottom skins of snare drums can be distinguished
from brushes on the top skin
- - mouth sounds are often very apparent
- - tape bleedthrough that's inaudible with the linestage can be heard without it
These sounds are mostly HF, mostly more information that just isn't
there with the line amp.
The tonal balance of the passive attenuator is better, that is, more to
my tastes :) Vocals dominates on vocal recordings, not bass. Piano
loudness appears better balanced across the keyboard.
The linestage definitely has more "jump" and "drive", this visceral
effect has got to be the much louder bass emphasis of the amplified
setup. It's hard to match levels between passive/amplified, since
matching the bass energy leaves the amplified setup with much lower
midrange and high end.
Have I just become acclimated to the "new" sound, or was it break-in? I
think the latter, because I can go back and hear the effect of the
12AX7s, and the initial disgusting sound is nowhere to be heard.
So, I conclude that a passive ladder attentuator sounds better than a
PAS2. It seems that I need to learn things the hard way. The ladder
has much better channel balance than the Alps. I also conclude that
the ladder sounds wonderful once it's broken in.
And even if I prefer the sound having no preamp vs. the PAS2, you may
still prefer listening to the sonic signature of some other preamp.
I turn the PAS2 on when I get nostalgic for that "tube" sound.
- - Eric
=========================================================================
From: "Fred Volz" <fcv@emotiveaudio.com>
Subject: Re: [JN] passive linestage experience
Date: Sun, 16 Jan 2000 03:28:43 -0500
Source: Sound Digest Archive v02.n405
- -----Original Message-----
From: Eric Weitzman <eweitzman@acm.org>
To: tubes <sound@lists.io.com>
Date: Sunday, January 16, 2000 1:48 AM
Subject: [JN] passive linestage experience
>I built a stereo ladder attenuator kit from Michael Percy. I considered
>the newer SMD series attenuators, but decided against the noise of the
>low-wattage resistors, what with so many of 'em in the circuit. The kit
>uses an older model Elma switch and Holco H4 1/2 watt resistors.
What would be cool is a ladder using larger value Holco SMD resistors (if
there is such a thing--I know they make low watt SMDs).
>
>When I first listened to the ladder attenuator, I was appalled. Did I
>really spend almost 200 bucks and a back-breaking evening of precision
>cutting and soldering for this stark, harsh, soul-less sound? The PAS2
>was much more musical, maybe it was the Alps, just as Fred Volz
>described in November when comparing an Alps pot with some resistors --
>
Hope this doesn't count toward my 15 minuets :o
>From: "Fred Volz" <fcv@emotiveaudio.com>
>> But the real disappointment for us was that none of these options sounded
as
>> good as the Alps pot. They weren't even close. All of the fixed resistors
>> sounded etched compared to the pot. Our final conclusion was that the
>> resistors made things SEEM more detailed. But, we weren't really hearing
any
>> more information--maybe even less. Rather, it seemed that the resistors
>> added emphasis to the leading edges of sounds. This results in what I
(and
>> probably others) call an increase in perceived detail--but not REAL
>> detail/more information. This was the exact opposite of what I expected
to
>> find.
>
>Then I remembered -- it takes time to break in components, no?
Well, yes AND no. Some components really seem to break in over time
(Blackgate caps in a big way, for example). But other components don't seem
to go through this process as dramatically, or at all. I have never noticed
break in with resistors, but that doesn't mean it's not happening. Our
stepped attenuators never got any better with time--to our ears.
Take your
>pick, a couple of hours, 100 hours, whatever it takes to take the edge
>off of a resistor, multiply that 24 times for each step of a 24-step
>attenuator. So I knocked a few db off of the high end in my crossovers
>and lived with the hardened sound.
>
>A while ago, I restored the crossovers to they way they were, and with
>my whiz-bang switchable linestage gizmo, I've done some careful
>listening.
>
>The passive attenuator has much more detail:
>- abrasive finger noises on basses are startlingly real
>- pitch of the skins on drums can be clearly heard
>- the rattling of the bottom skins of snare drums can be distinguished
> from brushes on the top skin
>- mouth sounds are often very apparent
>- tape bleedthrough that's inaudible with the linestage can be heard
without it
>
>These sounds are mostly HF, mostly more information that just isn't
>there with the line amp.
Are you absolutely sure that what you are hearing is not just the absence of
competing lower frequency information and, perhaps, an emphasis on upper
frequency information? And, are you comparing apples to apples: are you
comparing the attenuator to the Alps using both as either passives or
actives (in the PAS 2 circuit? If not, your observations may be affected by
the changing variable.
When we listened to a stepped attenuator compared to an Alps "black
beauty"--both as passive controllers--we heard more of the upper frequency
information also. And the bass seemed well defined and tight--if not deep.
But, upon further comparison, we concluded that there wasn't actually more
information with the stepped attenuator, just a different balance that
emphasized the "detail frequencies". Plus, we heard stuff we didn't like. Of
course, if you are hearing what you say you are hearing, great. More
importantly, if what you are hearing is musically satisfying to you--you
win. This is all that really matters anyway. It really is that simple.
>
>The tonal balance of the passive attenuator is better, that is, more to
>my tastes :) Vocals dominates on vocal recordings, not bass. Piano
>loudness appears better balanced across the keyboard.
>
>The linestage definitely has more "jump" and "drive", this visceral
>effect has got to be the much louder bass emphasis of the amplified
>setup. It's hard to match levels between passive/amplified, since
>matching the bass energy leaves the amplified setup with much lower
>midrange and high end.
>
>Have I just become acclimated to the "new" sound, or was it break-in?
An interesting question. I've tried to find this out with certain
components. For example, as I mentioned above, Blackgate caps (used in power
supply filter) really do seem to break-in dramatically over the first hour,
then slowly over about 24-48 hours. I actually went to the trouble of
testing this out--by ear only. But, sometimes I think I adjust to certain
sounds. Systems that seem lacking in upper frequency info sound better to me
after some period (maybe an hour) of listening. I think I simply compensate
for the softer top end. But, I haven't found it to work the other way:
bright, edgy stuff doesn't seem to get better. So, perhaps your attenuators
ARE breaking in and smoothing out with time.
I
>think the latter, because I can go back and hear the effect of the
>12AX7s, and the initial disgusting sound is nowhere to be heard.
>
>So, I conclude that a passive ladder attentuator sounds better than a
>PAS2.
Not actually a big surprise.
It seems that I need to learn things the hard way. The ladder
>has much better channel balance than the Alps. I also conclude that
>the ladder sounds wonderful once it's broken in.
>
>And even if I prefer the sound having no preamp vs. the PAS2, you may
>still prefer listening to the sonic signature of some other preamp.
All components have a sonic signature, the key is making them sound how you
imagine they should if they DIDN'T have one. The PAS 2, though I am fond of
it, has a REALLY big sonic signature--to my ear.
>
>I turn the PAS2 on when I get nostalgic for that "tube" sound.
>
>- Eric
>
The PAS 2 is a wonderful, sweet, romantic preamp. But, as you have now
discovered, it is a million miles behind what can be achieved with a good
passive line controller or, dare I say, a really good active linestage.
Best wishes,
Fred Volz
fcv@emotiveaudio.com
=========================================================================
From: =?iso-8859-1?Q?Bj=F8rn_Aaholm?= <bjorn@vt52.com>
Subject: [JN] Passive supplies...
Date: Mon, 11 Jun 2001 21:15:41 +0200
Source: Sound Digest Archive v02.n907
Okay guys...
I believe it's common knowledge that passive supplies rarely (if ever)
vary the output voltage symmetrically to varying loads. I.e. a passive
supply for a single ended stage will compress positive swings and
"amplify" negative swings (I'm talking input signal, of course phase
is inverted on the plate).
This effect is of course highly dependant on the impedance of the
supply and the current variations.
This might be something that will be discussed at the PSU Workshop in
Århus, but I'd like to hear a few opinions on this.
My limited experience tell me *I* like passive supplies best, but I'm
not a veteran :-)
Regards,
Bjørn Aaholm
=========================================================================
From: Peter Sikking <peter.sikking@virgin.net>
Subject: Re: [JN] Passive supplies... No comments or overlooked?
Date: Fri, 15 Jun 2001 15:24:35 +0100
Source: Sound Digest Archive v02.n911
Manfred wrote:
> A good passive supply is hard to beat IMO. While it's quite easy to improve
> bass performance of an amplifier by adding a regulated supply you have
> to take care that you don't mess up mids and hights.
So starting from jc's observation that 'you apparently can get away with murder
below 150Hz',
why not take the dual approach of active regulation below 150Hz, passive (LC)
above 150Hz.
This is implemented easily by having separate amps and speakers for < 150Hz.
Then observing that a regulator is a DC amplifier in your power supply, go
whole hog
and promote the regulator topology to amplifier service, with a passive supply.
If that means that you end up with a bass amp you don't like (what, a PP sand amp!),
then what was it doing in you power supply anyway..?
Now if you like me have no separate speakers < 150Hz and only one amp per channel,
you can implement the schizophrenic supply with a active regulator whose terminals
to the power supply are rolled off > 150Hz, followed by an LC filter with a 150Hz
corner frequency. This scheme is similar to what Phil 'tube' has been promoting.
A thing that still can go wrong with this scheme is that the time domain errors
that regulators make in the < 150Hz region still 'mess up mids and hights',
even with separate amps and speakers.
One last thought: instead of concentrating time and effort on a stable regulator,
you can also put it into lo-DCR & lo-inductance schemes. The overall series impedance
- --DCR + Z(total inductance)--short-circuits the rising cap impedance for low frequencies.
--ps/032
=========================================================================
From: MHuber@t-online.de (Manfred Huber)
Subject: Re: [JN] Passive supplies... No comments or overlooked?
Date: Sat, 16 Jun 2001 10:29:23 +0200
Source: Sound Digest Archive v02.n912
Hello Peter,
>If that means that you end up with a bass amp you don't like (what, a PP sand amp!),
>then what was it doing in you power supply anyway..?
No problem with that. In fact this is what I use these days. A solid state amp
on the woofers working up to 300Hz and a SE45 (passive supply ;-) above 300Hz.
>Now if you like me have no separate speakers < 150Hz and only one amp per channel,
>you can implement the schizophrenic supply with a active regulator whose terminals
>to the power supply are rolled off > 150Hz, followed by an LC filter with a 150Hz
>corner frequency. This scheme is similar to what Phil 'tube' has been promoting.
Interesting approach. Getting constant impedance in the cross over region
could be a challenge. Do you want to bring such a supply to Arhus ;-)
Regards
Manfred
- ------------------
Manfred Huber
MHuber@t-online.de
- ------------------
=========================================================================
From: "Larry D. Moore" <l-moore@onu.edu>
Subject: [JN] Patent Attorney
Date: Tue, 09 Jan 2001 20:21:32 -0500
Source: Sound Digest Archive v02.n779
Apparently there is something going on on the bass list? I recieved a ton
of email about it. If any one needs help, I'd be glad to provide
asssitance. Please contact me.
I would also caution that much of what I read that has been forwarded to me
is far from complete in its anaylitical content and one should follow any
of this without consulting with a patent attorney.
L.D. Moore
=========================================================================
From: "Larry D. Moore" <l-moore@onu.edu>
Subject: [JN] Patent Attorney
Date: Tue, 09 Jan 2001 20:33:19 -0500
Source: Sound Digest Archive v02.n779
Sorry typo....
should "not" follow without seeking assitance.
My point is that I really don't want to get into this in this or any other
form.
Back to audio, tubes, music, passion......
L.D. Moore
=========================================================================
From: "Dave Aukerman" <aukdav@wcoil.com>
Subject: Re: [JN] Patent Attorney
Date: Tue, 9 Jan 2001 21:20:30 -0500
Source: Sound Digest Archive v02.n779
How much money do you have to spend?
Dave
- ----- Original Message -----
From: "David Crittle" <retrovox@bigpond.com>
To: <sound@lists.io.com>
Sent: Tuesday, January 09, 2001 8:46 PM
Subject: [JN] Patent Attorney
> I know zilch about about patent law, but I have one question for those who
> may be better informed than me:
>
> Do patent/license restrictions apply only to commercial products offered
> for sale? That is, can I utilize patented ideas/concepts/designs/whatever
> in something that I build for my own private use?
>
> critter
>
>
>
=========================================================================
From: "Dave Aukerman" <aukdav@wcoil.com>
Subject: Re: [JN] Patent Attorney
Date: Tue, 9 Jan 2001 21:23:15 -0500
Source: Sound Digest Archive v02.n779
Errr, never mind. Brain fart.
Dave
- ----- Original Message -----
From: "David Crittle" <retrovox@bigpond.com>
To: <sound@lists.io.com>
Sent: Tuesday, January 09, 2001 8:46 PM
Subject: [JN] Patent Attorney
> I know zilch about about patent law, but I have one question for those who
> may be better informed than me:
>
> Do patent/license restrictions apply only to commercial products offered
> for sale? That is, can I utilize patented ideas/concepts/designs/whatever
> in something that I build for my own private use?
>
> critter
>
>
>
=========================================================================
From: David Crittle <retrovox@bigpond.com>
Subject: [JN] Patent Attorney
Date: Wed, 10 Jan 2001 12:46:22 +1100
Source: Sound Digest Archive v02.n779
I know zilch about about patent law, but I have one question for those who
may be better informed than me:
Do patent/license restrictions apply only to commercial products offered
for sale? That is, can I utilize patented ideas/concepts/designs/whatever
in something that I build for my own private use?
critter
=========================================================================
From: "Thomas Sylvester" <TRS@carlsmith.com>
Subject: Re: [JN] Patent Attorney
Date: Wed, 10 Jan 2001 08:39:06 -1000
Source: Sound Digest Archive v02.n780
Hi Dave:
The short answer (insert appropriate discalimers, waivers of liability, &c. &c.) is "yes".
Regards,
Tom Sylvester
>>> David Crittle <retrovox@bigpond.com> 01/09/01 03:46PM >>>
I know zilch about about patent law, but I have one question for those who
may be better informed than me:
Do patent/license restrictions apply only to commercial products offered
for sale? That is, can I utilize patented ideas/concepts/designs/whatever
in something that I build for my own private use?
critter
=========================================================================
From: Douglas Purl <dcp@selway.umt.edu>
Subject: Re: [JN] Patent Attorney
Date: Wed, 10 Jan 2001 12:33:46 -0700 (MST)
Source: Sound Digest Archive v02.n780
On Wed, 10 Jan 2001, David Crittle wrote:
> I know zilch about about patent law, but I have one question for those who
> may be better informed than me:
>
> Do patent/license restrictions apply only to commercial products offered
> for sale? That is, can I utilize patented ideas/concepts/designs/whatever
> in something that I build for my own private use?
It depends on your motive and method. The word "patent" means "open to
inspection." Patents are time-limited exclusive licenses to profit
granted in order to induce the patentee to disclose the why and how. The
principle of the patent is to foster refinement of materials, methods, and
knowledge through competition.
If you wish to explore patented technology in order to understand or
improve on it, you are not only permitted to do so, you are encouraged to.
If, however, for the sake of example, you build multiple copies of a
patented device and install them in your chain of mom and pop porno
flickatoria, you are depriving the patentee of licensed spoils and can
have your ass torted.
Doug Purl
=========================================================================
From: Sridhar Gantimahapatruni <Ganti@acta.com>
Subject: [JN] Patting my own back
Date: Mon, 20 Dec 1999 19:35:10 -0800
Source: Sound Digest Archive v02.n368
This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.
- ------_=_NextPart_001_01BF4B64.62835450
Content-Type: text/plain;
charset="iso-8859-1"
Hi guys
I had John Atwood over to my place last weekend, and he listened to my
811A monoblocks, and given below are his comments. BTW, for those
who are not aware, photo's of these amps are on his web-site, inside the
products page
Could not resist patting myself on the back ):
Thanks
ganti
* These comments are there on his web page also..
- ----------------------------------------------------------------------------
- ---------------
I recently had a chance to hear Ganti's 811
amps at his home - listening to LPs through
his Vanderstein speakers. Compared with his
earlier amps,the soundstage was big - way
beyond the edge of the speakers.
The low-level detail (concert hall ambience,
decays of instument sounds, etc) was incredible.
The tonal balance was excellent, too.
This amp definitely shows that:
a) class A2 can sound very good, and
b) with good transformers, transformer
coupling can be excellent, too.
- - John Atwood
- ------_=_NextPart_001_01BF4B64.62835450
Content-Type: text/html;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
<HTML>
<HEAD>
<META HTTP-EQUIV=3D"Content-Type" CONTENT=3D"text/html; =
charset=3Diso-8859-1">
<META NAME=3D"Generator" CONTENT=3D"MS Exchange Server version =
5.5.2448.0">
<TITLE>Patting my own back</TITLE>
</HEAD>
<BODY>
<BR>
<P><FONT FACE=3D"Tahoma">Hi guys</FONT>
</P>
<P><FONT FACE=3D"Tahoma">I had John Atwood over to my place last =
weekend, and he listened to my</FONT>
<BR><FONT FACE=3D"Tahoma">811A monoblocks, and given below are his =
comments. BTW, for those</FONT>
<BR><FONT FACE=3D"Tahoma">who are not aware, photo's of these amps are =
on his web-site, inside the</FONT>
<BR><FONT FACE=3D"Tahoma">products page</FONT>
</P>
<P><FONT FACE=3D"Tahoma">Could not resist patting myself on the back =
):</FONT>
</P>
<P><FONT FACE=3D"Tahoma">Thanks</FONT>
<BR><FONT FACE=3D"Tahoma">ganti</FONT>
</P>
<P><FONT FACE=3D"Tahoma">* These comments are there on his web page =
also..</FONT>
<BR><FONT =
FACE=3D"Tahoma">--------------------------------------------------------=
- -----------------------------------</FONT>
</P>
<P><FONT SIZE=3D5 FACE=3D"Courier">I recently had a chance to hear =
Ganti's 811 </FONT>
<BR><FONT SIZE=3D5 FACE=3D"Courier">amps at his home - listening to LPs =
through </FONT>
<BR><FONT SIZE=3D5 FACE=3D"Courier">his Vanderstein speakers. Compared =
with his </FONT>
<BR><FONT SIZE=3D5 FACE=3D"Courier">earlier amps,the soundstage was big =
- - way </FONT>
<BR><FONT SIZE=3D5 FACE=3D"Courier">beyond the edge of the speakers. =
</FONT>
<BR><FONT SIZE=3D5 FACE=3D"Courier">The low-level detail (concert hall =
ambience, </FONT>
<BR><FONT SIZE=3D5 FACE=3D"Courier">decays of instument sounds, etc) =
was incredible. </FONT>
<BR><FONT SIZE=3D5 FACE=3D"Courier">The tonal balance was excellent, =
too. </FONT>
<BR><FONT SIZE=3D5 FACE=3D"Courier">This amp definitely shows that: =
</FONT>
<BR> <FONT SIZE=3D5 =
FACE=3D"Courier">a) class A2 can sound very good, and </FONT>
<BR> <FONT SIZE=3D5 =
FACE=3D"Courier">b) with good transformers, transformer </FONT>
<BR> =
<FONT SIZE=3D5 =
FACE=3D"Courier">coupling can be excellent, too.</FONT>
</P>
<P><FONT SIZE=3D5 FACE=3D"Courier">- John Atwood </FONT>
</P>
</BODY>
</HTML>
- ------_=_NextPart_001_01BF4B64.62835450--
=========================================================================
From: "Paul De Raymond Leclercq" <Pderl@btinternet.com>
Subject: Re: [JN] Re: Paul De Raymond Leclercq and tube rec'ns eg the 6CG7
Date: Tue, 3 Jul 2001 08:51:49 -0700
Source: Sound Digest Archive v02.n919
>
> What is it about this noval version of the 6SN7?
>
Hello,
Does this question relate to Mr Jones's question about alternatives to 5687
and 7119?
The alternatives that I suggested were ones that I selected as being driver
valves of broadly similar character - i.e medium-mu double triodes with
fairly low anode resistance.
I am aware of 6CG7/6FQ7's reputation for good sound, but its anode
resistance (which is the same as 6/12SN7, 12SX7, 7A4, 7N7, 6J5 etc.)
disqualified it from this particular thread in my view.
6CG7 vs 12AX7? no contest, but a very unequal one too.
Regards
Paul
=========================================================================
From: "Timothy James Bailey" <tim_bailey@bigpond.com>
Subject: [JN] Re: Paul De Raymond Leclercq and tube rec'ns eg the 6CG7
Date: Tue, 3 Jul 2001 13:45:59 +1000
Source: Sound Digest Archive v02.n919
Paul et al,
I know this may seem a hobby horse of mine.
Howsomever it is rarely mentioned or recommended in this group, in cases
when I would think it is a suitable alternative.
What is it about this noval version of the 6SN7?
Is availability a problem? eg. the EI factory.
Is quality variation a problem?
Is sound quality a problem?
Is it just too tall?
IMO this tube made a huge improvement in lowering distortion in my two Leak
Stereo 20's when used as the phase splitter driver, replacing a 12AX7. Yes
the circuit is different, not just the pin-outs, and there is a FET current
source.
Leak had originally used a 12AX7 there, and as the input tube, too. For
cost reasons and perceived availability, I think.
Tim B
=========================================================================
From: Jeremy Epstein <jepstein@shwd.com>
Subject: [JN] Paul Joppa? Paul Joppa?
Date: Thu, 10 Jun 1999 09:28:18 -0400
Source: Sound Digest Archive v02.n174
Last I knew, he was off JoeNet, and email to pdj@ISDNseattle.net (which
is the address I had,) is bouncing back. Anybody have a current email
address for Paul Joppa?
- -j
- --
=====================================
Jeremy Epstein .... jepstein@shwd.com
=====================================
=========================================================================
From: TubeGarden@aol.com
Subject: [JN] Pay no attention to that little man behind the curtain
Date: Sun, 29 Apr 2001 20:22:52 EDT
Source: Sound Digest Archive v02.n876
- --part1_ff.5a45183.281e0a5c_boundary
Content-Type: text/plain; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Greets!
So after resting up after the drive to LA, I looked, and, to my not very
great surprise, I had wired the speakers, um, strangely :)
Now Playing is the Lambda 15" triple magnet on 80 Hz edgarhorn wired direct
to the 4 ohm taps.
The Taiwan metal horn tweeter is on the 8 ohm tap with a 5.04 uF cap cluster
in series.
This MBD (Mixed Blessing Disease) sure plays me for a moron sometimes :)
Anyway, WOW!
Of course, now that I believe Nick McK is a Genius, he has gone legit ...
Oh, well, I got mine :)
Happy Ears!
Al B^}
PS Bruce Edgar is a Genius, too, but I knew That before fixing the wires :)
- --part1_ff.5a45183.281e0a5c_boundary
Content-Type: text/html; charset="US-ASCII"
Content-Transfer-Encoding: 7bit
<HTML><FONT FACE=arial,helvetica><BODY BGCOLOR="#ffffff"><FONT SIZE=2>Greets!
<BR>
<BR>So after resting up after the drive to LA, I looked, and, to my not very
<BR>great surprise, I had wired the speakers, um, strangely :)
<BR>
<BR>Now Playing is the Lambda 15" triple magnet on 80 Hz edgarhorn wired direct
<BR>to the 4 ohm taps.
<BR>
<BR>The Taiwan metal horn tweeter is on the 8 ohm tap with a 5.04 uF cap cluster
<BR>in series.
<BR>
<BR>This MBD (Mixed Blessing Disease) sure plays me for a moron sometimes :)
<BR>
<BR>Anyway, WOW!
<BR>
<BR>Of course, now that I believe Nick McK is a Genius, he has gone legit ...
<BR>
<BR>Oh, well, I got mine :)
<BR>
<BR>Happy Ears!
<BR>Al B^}
<BR>
<BR>PS Bruce Edgar is a Genius, too, but I knew That before fixing the wires :)</FONT></HTML>
- --part1_ff.5a45183.281e0a5c_boundary--
=========================================================================
From: Steve Van Osdell <svanos@queencity.com>
Subject: Re: SV: [JN] Pay no attention to that little man behind the curtain
Date: Mon, 30 Apr 2001 12:31:27 -0400
Source: Sound Digest Archive v02.n876
- --------------8D2E1BA76639128A98B8E991
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Bruce Edgar does not have a home page at the present time. He is not
the big 'corporation' that some may think. His health has been bad in
recent months due to blood pressure, but has improved of late. He told
me recently that he is hoping to have one of his son's friends, who is
supposedly a 'guru' web designer, to set him up with a web page. I
sure wish he had one.
He did have a photo of his 'Titan' speakers up along with his address
and phone number on a webpage that was something like
www.euphonosaudio.com
Thanks, Steve
Jan Hass wrote:
> Hi AlWhat is the name of the Taiwan metal horn tweeter. Dos the
> genious Mr. Bruce Edgar have some kind of homepage where it would be
> passible see these horns ?greatings Jan Hass
>
>
> Greets!
>
> So after resting up after the drive to LA, I looked, and, to
> my not very
> great surprise, I had wired the speakers, um, strangely :)
>
> Now Playing is the Lambda 15" triple magnet on 80 Hz
> edgarhorn wired direct
> to the 4 ohm taps.
>
> The Taiwan metal horn tweeter is on the 8 ohm tap with a
> 5.04 uF cap cluster
> in series.
>
> This MBD (Mixed Blessing Disease) sure plays me for a moron
> sometimes :)
>
> Anyway, WOW!
>
> Of course, now that I believe Nick McK is a Genius, he has
> gone legit ...
>
> Oh, well, I got mine :)
>
> Happy Ears!
> Al B^}
>
> PS Bruce Edgar is a Genius, too, but I knew That before
> fixing the wires :)
>
- --------------8D2E1BA76639128A98B8E991
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit
<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
<body bgcolor="#FFFFFF">
Bruce Edgar does not have a home page at the present time. He is
not the big 'corporation' that some may think. His health has been
bad in recent months due to blood pressure, but has improved of late.
He told me recently that he is hoping to have one of his son's friends,
who is supposedly a 'guru' web designer, to set him up with a web page.
I sure wish he had one.
<p>He did have a photo of his 'Titan' speakers up along with his address
and phone number on a webpage that was something like www.euphonosaudio.com
<p>Thanks, Steve
<p>Jan Hass wrote:
<blockquote TYPE=CITE> <span class=010412311-30042001><font face="Verdana"><font color="#0000FF
"><font size=-1>Hi
Al</font></font></font></span><span
class=010412311-30042001></span><span class=010412311-30042001><font face="Verdana"><font color="#00
00FF"><font size=-1>What
is the name of the Taiwan metal horn tweeter. Dos the genious Mr. Bruce
Edgar have some kind of homepage where it would be passible see these horns
?</font></font></font></span><span
class=010412311-30042001></span><span
class=010412311-30042001><font face="Verdana"><font color="#0000FF"><font size=-1>greatings
Jan Hass</font></font></font></span>
<br>
<blockquote><font face="arial,helvetica"><font color="#0000FF"><font size=-1>Greets!</font></font></
font>
<p><font face="arial,helvetica"><font color="#0000FF"><font size=-1>So
after resting up after the drive to LA, I looked, and, to my not very</font></font></font>
<br><font face="arial,helvetica"><font color="#0000FF"><font size=-1>great
surprise, I had wired the speakers, um, strangely :)</font></font></font>
<p><font face="arial,helvetica"><font color="#0000FF"><font size=-1>Now
Playing is the Lambda 15" triple magnet on 80 Hz edgarhorn wired direct</font></font></font>
<br><font face="arial,helvetica"><font color="#0000FF"><font size=-1>to
the 4 ohm taps.</font></font></font>
<p><font face="arial,helvetica"><font color="#0000FF"><font size=-1>The
Taiwan metal horn tweeter is on the 8 ohm tap with a 5.04 uF cap cluster</font></font></font>
<br><font face="arial,helvetica"><font color="#0000FF"><font size=-1>in
series.</font></font></font>
<p><font face="arial,helvetica"><font color="#0000FF"><font size=-1>This
MBD (Mixed Blessing Disease) sure plays me for a moron sometimes :)</font></font></font>
<p><font face="arial,helvetica"><font color="#0000FF"><font size=-1>Anyway,
WOW!</font></font></font>
<p><font face="arial,helvetica"><font color="#0000FF"><font size=-1>Of
course, now that I believe Nick McK is a Genius, he has gone legit ...</font></font></font>
<p><font face="arial,helvetica"><font color="#0000FF"><font size=-1>Oh,
well, I got mine :)</font></font></font>
<p><font face="arial,helvetica"><font color="#0000FF"><font size=-1>Happy
Ears!</font></font></font>
<br><font face="arial,helvetica"><font color="#0000FF"><font size=-1>Al
B^}</font></font></font>
<p><font face="arial,helvetica"><font color="#0000FF"><font size=-1>PS
Bruce Edgar is a Genius, too, but I knew That before fixing the wires :)</font></font></font></block
quote>
</blockquote>
</body>
</html>
- --------------8D2E1BA76639128A98B8E991--
=========================================================================
From: "Jan Hass" <jh@hifi-analyse.dk>
Subject: SV: [JN] Pay no attention to that little man behind the curtain
Date: Mon, 30 Apr 2001 13:29:42 +0200
Source: Sound Digest Archive v02.n876
This is a multi-part message in MIME format.
- ------=_NextPart_000_0000_01C0D179.9CF4A2A0
Content-Type: text/plain;
charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Hi Al
What is the name of the Taiwan metal horn tweeter. Dos the genious Mr. Bruce
Edgar have some kind of homepage where it would be passible see these horns
?
greatings Jan Hass
Greets!
So after resting up after the drive to LA, I looked, and, to my not very
great surprise, I had wired the speakers, um, strangely :)
Now Playing is the Lambda 15" triple magnet on 80 Hz edgarhorn wired
direct
to the 4 ohm taps.
The Taiwan metal horn tweeter is on the 8 ohm tap with a 5.04 uF cap
cluster
in series.
This MBD (Mixed Blessing Disease) sure plays me for a moron sometimes :)
Anyway, WOW!
Of course, now that I believe Nick McK is a Genius, he has gone legit ...
Oh, well, I got mine :)
Happy Ears!
Al B^}
PS Bruce Edgar is a Genius, too, but I knew That before fixing the wires
:)
- ------=_NextPart_000_0000_01C0D179.9CF4A2A0
Content-Type: text/html;
charset="US-ASCII"
Content-Transfer-Encoding: quoted-printable
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Dus-ascii">
<META content=3D"MSHTML 5.50.4134.100" name=3DGENERATOR></HEAD>
<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DVerdana color=3D#0000ff size=3D2><SPAN =
class=3D010412311-30042001>Hi=20
Al</SPAN></FONT></DIV>
<DIV><FONT face=3DVerdana color=3D#0000ff size=3D2><SPAN=20
class=3D010412311-30042001></SPAN></FONT> </DIV>
<DIV><FONT face=3DVerdana color=3D#0000ff size=3D2><SPAN =
class=3D010412311-30042001>What=20
is the name of the Taiwan metal horn tweeter. Dos the genious Mr. Bruce =
Edgar=20
have some kind of homepage where it would be passible see these horns=20
?</SPAN></FONT></DIV>
<DIV><FONT face=3DVerdana color=3D#0000ff size=3D2><SPAN=20
class=3D010412311-30042001></SPAN></FONT> </DIV>
<DIV><FONT face=3DVerdana color=3D#0000ff size=3D2><SPAN=20
class=3D010412311-30042001>greatings Jan Hass</SPAN></FONT></DIV>
<DIV><FONT face=3DTahoma size=3D2><BR><BR></FONT> </DIV>
<BLOCKQUOTE><FONT face=3Darial,helvetica><FONT color=3D#0000ff =
size=3D2>Greets!=20
<BR><BR>So after resting up after the drive to LA, I looked, and, to =
my not=20
very <BR>great surprise, I had wired the speakers, um, strangely :)=20
<BR><BR>Now Playing is the Lambda 15" triple magnet on 80 Hz edgarhorn =
wired=20
direct <BR>to the 4 ohm taps. <BR><BR>The Taiwan metal horn tweeter is =
on the=20
8 ohm tap with a 5.04 uF cap cluster <BR>in series. <BR><BR>This MBD =
(Mixed=20
Blessing Disease) sure plays me for a moron sometimes :) =
<BR><BR>Anyway, WOW!=20
<BR><BR>Of course, now that I believe Nick McK is a Genius, he has =
gone legit=20
... <BR><BR>Oh, well, I got mine :) <BR><BR>Happy Ears! <BR>Al =
B^}=20
<BR><BR>PS Bruce Edgar is a Genius, too, but I knew That before fixing =
the=20
wires :)</FONT> </FONT></BLOCKQUOTE></BODY></HTML>
- ------=_NextPart_000_0000_01C0D179.9CF4A2A0--
=========================================================================
From: "Jan Hass" <jh@hifi-analyse.dk>
Subject: SV: SV: [JN] Pay no attention to that little man behind the curtain / Dr. Edgar
Date: Tue, 1 May 2001 00:22:47 +0200
Source: Sound Digest Archive v02.n876
This is a multi-part message in MIME format.
- ------=_NextPart_000_0015_01C0D1D4.D9757780
Content-Type: text/plain;
charset="US-ASCII"
Content-Transfer-Encoding: 7bit
Hi Steve
Thanks for your reply. I had already found the Euphono website but I
have been unable to open this
webaddress.
greatings Jan Hass
Bruce Edgar does not have a home page at the present time. He is not the
big 'corporation' that some may think. His health has been bad in recent
months due to blood pressure, but has improved of late. He told me recently
that he is hoping to have one of his son's friends, who is supposedly a
'guru' web designer, to set him up with a web page. I sure wish he had
one.
He did have a photo of his 'Titan' speakers up along with his address and
phone number on a webpage that was something like www.euphonosaudio.com
Thanks, Steve
Jan Hass wrote:
Hi AlWhat is the name of the Taiwan metal horn tweeter. Dos the genious
Mr. Bruce Edgar have some kind of homepage where it would be passible see
these horns ?greatings Jan Hass
Greets!
So after resting up after the drive to LA, I looked, and, to my not
very
great surprise, I had wired the speakers, um, strangely :)
Now Playing is the Lambda 15" triple magnet on 80 Hz edgarhorn wired
direct
to the 4 ohm taps.
The Taiwan metal horn tweeter is on the 8 ohm tap with a 5.04 uF cap
cluster
in series.
This MBD (Mixed Blessing Disease) sure plays me for a moron sometimes
:)
Anyway, WOW!
Of course, now that I believe Nick McK is a Genius, he has gone legit
...
Oh, well, I got mine :)
Happy Ears!
Al B^}
PS Bruce Edgar is a Genius, too, but I knew That before fixing the
wires :)
- ------=_NextPart_000_0015_01C0D1D4.D9757780
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charset="US-ASCII"
Content-Transfer-Encoding: quoted-printable
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<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Dus-ascii">
<META content=3D"MSHTML 5.50.4134.100" name=3DGENERATOR></HEAD>
<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DTahoma size=3D2><SPAN=20
class=3D970591822-30042001> =
<FONT=20
face=3DVerdana color=3D#0000ff>Hi Steve</FONT></SPAN></FONT></DIV>
<DIV><FONT face=3DTahoma size=3D2><SPAN=20
class=3D970591822-30042001> =
<FONT=20
face=3DVerdana color=3D#0000ff>Thanks for your reply. I had already =
found the=20
Euphono website but I have been unable to open=20
this </FONT></=
SPAN></FONT></DIV>
<DIV><FONT face=3DTahoma color=3D#0000ff size=3D2><SPAN=20
class=3D970591822-30042001> &nbs=
p;webaddress. </SPAN></FONT></DIV>
<DIV><FONT face=3DTahoma color=3D#0000ff size=3D2><SPAN=20
class=3D970591822-30042001></SPAN></FONT> </DIV>
<DIV><FONT face=3DTahoma size=3D2><SPAN class=3D970591822-30042001><FONT =
color=3D#0000ff> greatings=
Jan=20
Hass</FONT> &n=
bsp; &nb=
sp; =20
</SPAN></FONT></DIV>
<BLOCKQUOTE dir=3Dltr style=3D"MARGIN-RIGHT: 0px">Bruce Edgar does not =
have a home=20
page at the present time. He is not the big 'corporation' that =
some may=20
think. His health has been bad in recent months due to blood =
pressure,=20
but has improved of late. He told me recently that he is hoping =
to have=20
one of his son's friends, who is supposedly a 'guru' web designer, to =
set him=20
up with a web page. I sure wish he had one.=20
<P>He did have a photo of his 'Titan' speakers up along with his =
address and=20
phone number on a webpage that was something like =
www.euphonosaudio.com=20
<P>Thanks, Steve=20
<P>Jan Hass wrote:=20
<BLOCKQUOTE TYPE=3D"CITE"> <SPAN class=3D010412311-30042001><FONT =
face=3DVerdana><FONT color=3D#0000ff><FONT size=3D-1>Hi=20
Al</FONT></FONT></FONT></SPAN><SPAN =
class=3D010412311-30042001></SPAN><SPAN=20
class=3D010412311-30042001><FONT face=3DVerdana><FONT =
color=3D#0000ff><FONT=20
size=3D-1>What is the name of the Taiwan metal horn tweeter. Dos the =
genious=20
Mr. Bruce Edgar have some kind of homepage where it would be =
passible see=20
these horns ?</FONT></FONT></FONT></SPAN><SPAN=20
class=3D010412311-30042001></SPAN><SPAN =
class=3D010412311-30042001><FONT=20
face=3DVerdana><FONT color=3D#0000ff><FONT size=3D-1>greatings Jan=20
Hass</FONT></FONT></FONT></SPAN> <BR> =20
<BLOCKQUOTE><FONT face=3Darial,helvetica><FONT color=3D#0000ff><FONT =
size=3D-1>Greets!</FONT></FONT></FONT>=20
<P><FONT face=3Darial,helvetica><FONT color=3D#0000ff><FONT =
size=3D-1>So after=20
resting up after the drive to LA, I looked, and, to my not=20
very</FONT></FONT></FONT> <BR><FONT face=3Darial,helvetica><FONT=20
color=3D#0000ff><FONT size=3D-1>great surprise, I had wired the =
speakers, um,=20
strangely :)</FONT></FONT></FONT>=20
<P><FONT face=3Darial,helvetica><FONT color=3D#0000ff><FONT =
size=3D-1>Now=20
Playing is the Lambda 15" triple magnet on 80 Hz edgarhorn wired=20
direct</FONT></FONT></FONT> <BR><FONT face=3Darial,helvetica><FONT =
color=3D#0000ff><FONT size=3D-1>to the 4 ohm =
taps.</FONT></FONT></FONT>=20
<P><FONT face=3Darial,helvetica><FONT color=3D#0000ff><FONT =
size=3D-1>The Taiwan=20
metal horn tweeter is on the 8 ohm tap with a 5.04 uF cap=20
cluster</FONT></FONT></FONT> <BR><FONT =
face=3Darial,helvetica><FONT=20
color=3D#0000ff><FONT size=3D-1>in series.</FONT></FONT></FONT>=20
<P><FONT face=3Darial,helvetica><FONT color=3D#0000ff><FONT =
size=3D-1>This MBD=20
(Mixed Blessing Disease) sure plays me for a moron sometimes=20
:)</FONT></FONT></FONT>=20
<P><FONT face=3Darial,helvetica><FONT color=3D#0000ff><FONT =
size=3D-1>Anyway,=20
WOW!</FONT></FONT></FONT>=20
<P><FONT face=3Darial,helvetica><FONT color=3D#0000ff><FONT =
size=3D-1>Of course,=20
now that I believe Nick McK is a Genius, he has gone legit=20
...</FONT></FONT></FONT>=20
<P><FONT face=3Darial,helvetica><FONT color=3D#0000ff><FONT =
size=3D-1>Oh, well,=20
I got mine :)</FONT></FONT></FONT>=20
<P><FONT face=3Darial,helvetica><FONT color=3D#0000ff><FONT =
size=3D-1>Happy=20
Ears!</FONT></FONT></FONT> <BR><FONT face=3Darial,helvetica><FONT=20
color=3D#0000ff><FONT size=3D-1>Al =
B^}</FONT></FONT></FONT>=20
<P><FONT face=3Darial,helvetica><FONT color=3D#0000ff><FONT =
size=3D-1>PS Bruce=20
Edgar is a Genius, too, but I knew That before fixing the wires=20
=
:)</FONT></FONT></FONT></P></BLOCKQUOTE></BLOCKQUOTE></BLOCKQUOTE></BODY>=
</HTML>
- ------=_NextPart_000_0015_01C0D1D4.D9757780--
=========================================================================
From: Robert C Chambers <rchamber@norwich.edu>
Subject: [JN] PayPal: Another Take
Date: Fri, 10 Nov 2000 09:00:11 -0500 (EST)
Source: Sound Digest Archive v02.n728
Hi-
Check ebay #488586837 (an RCA 2A3) for some comments from an ex-PayPal
user.
Robert
=========================================================================
From: "Darryl Lock" <dklock@ieee.org>
Subject: RE: [JN] PayPal: Another Take
Date: Sat, 11 Nov 2000 09:03:10 +1000
Source: Sound Digest Archive v02.n728
You have to be careful of unreal expectations of some people.
For example. This person also demands (in large capital letters) that
payments be received within 10 days, and he sells internationally! I can
tell you it can take as long as a month at times to send a normal airmail
letter with a cheque in it - has happened quite a few times to me.
Darryl
>
>
> Hi-
>
> Check ebay #488586837 (an RCA 2A3) for some comments from an ex-PayPal
> user.
>
> Robert
>
=========================================================================
From: rfrancis@glasscity.net
Subject: [JN] PayPal goes International!
Date: Thu, 9 Nov 2000 12:09:15 -0800
Source: Sound Digest Archive v02.n727
As this very topic caused a stir a couple months ago, I thought
this might interest enough folks to warrant a post. PayPal, which
is a very cool way to push money around without paper, now works
for these countries:
Australia
Austria
Belgium
Brazil
Canada
Denmark
France
Germany
Hong Kong
Ireland
Israel
Italy
Japan
Mexico
Netherlands
New Zealand
Norway
Portugal
Singapore
South Africa
South Korea
Spain
Sweden
Switzerland
United Kingdom
That covers a lot of folks on this list! Get details from www.paypal.com.
I have no personal interest, just a satisfied user, blah blah.
BTW, if I'm supposed to send you some tubes... I'll get to it.
I'm just keeping up with ebay sales at the moment, but hang in
there.
Rick
- -----
Sent using MailStart.com ( http://MailStart.Com/welcome.html )
The FREE way to access your mailbox via any web browser, anywhere!
=========================================================================
From: =?us-ascii?Q?Bjorn_Aaholm?= <bjorn@vt52.com>
Subject: SV: [JN] PayPal goes International!
Date: Thu, 9 Nov 2000 22:00:27 +0100
Source: Sound Digest Archive v02.n727
Rick Francis typoed:
> As this very topic caused a stir a couple months ago, I thought
> this might interest enough folks to warrant a post. PayPal, which
> is a very cool way to push money around without paper, now works
> for these countries:
*SNIP*
That is indeed good news!
Thanks for letting us all know Rick :-)
Still nobody who's had bad experience with this service?
>
> That covers a lot of folks on this list! Get details from www.paypal.com.
Yep, sure does.
regards,
Bjorn Aaholm
=========================================================================
From: Anders Blix <anders.blix@tv2.no>
Subject: [JN] PC as PWM bass DAC
Date: Mon, 7 May 2001 21:29:42 +0200
Source: Sound Digest Archive v02.n880
Hello again folks!
I have some questions for you:
Is it posible to controll EVERY single bit putt out on the digital outputt
on a soundcard. I think I would perfer an electrical connection as vell
(even AES/EBU if possible).
My plan is to use the bits going out from the soundcard to be the signal
going directly to the power switches (throug some driving chips or
something, but nothing with anny logic).
I was hoping to not have to have an inteligent card that strips out the
databits and syncronize them. Not unless this is possible to get a chip or
something that does this without much work.
The idea was to use it for only low frequencies.
I was going to make the PC calculate the PWM signal from the inputt. This
will be like a low frequency only TACT.
Anny of you know how the TACT achieve full frequency range and dynamic range
when they only uses 8 bits for pulse with controll at 8 times 44.1 kHz???
Anders
=========================================================================
From: Remco Stoutjesdijk <remco@ultranalog.com>
Subject: Re: [JN] PC as PWM bass DAC
Date: Mon, 07 May 2001 22:37:00 +0200
Source: Sound Digest Archive v02.n880
Hi,
>Is it posible to controll EVERY single bit putt out on the digital outputt
>on a soundcard. I think I would perfer an electrical connection as vell
>(even AES/EBU if possible).
Yes, but that requires mucho horsepower processors and memory! You'd have to dream up a .wav stream
in real time and DMA it to the sound card.
>My plan is to use the bits going out from the soundcard to be the signal
>going directly to the power switches (throug some driving chips or
>something, but nothing with anny logic).
A digital audio receiver, perhaps? Such as the Crystal 8412/8414... If you plan to drive a class-D p
ower stage directly, a dedicated output port may be more convenient, e.g. the parallel port.
>The idea was to use it for only low frequencies.
Theoreticaaly, a switching speed of about 3 times the max freq. of your signal suffices. However, I'
d always choose the switching freq (far) above 20 kHz to avoid interference and simplify filtering.
BTW, a simple PW Modulator doesn't take an entire DSP... I've even used the 555 with good results. T
hat's about $1k cheaper. A little more fancy like the TacT uses is not that hard to build. And I'd a
void use of a PC for hi-performance audio at any time. Not to mention the recent thread on fan noise
...
>I was going to make the PC calculate the PWM signal from the inputt. This
>will be like a low frequency only TACT.
>
>Anny of you know how the TACT achieve full frequency range and dynamic range
>when they only uses 8 bits for pulse with controll at 8 times 44.1 kHz???
TacT Equibit uses a third order noise shaping loop. But even then, it's under DIN spec.
Regards,
Remco
- --
http://www.ultranalog.com
=========================================================================
From: "Ron & Tamara" <ron.steinberg@sympatico.ca>
Subject: Re: [JN] PCB layout software
Date: Mon, 18 Sep 2000 21:54:44 -0400
Source: Sound Digest Archive v02.n666
Kurt,
Try EagleCad, can't remember the web site but they have a freeware version
that will do boards up to about 3x4 inches double sided, and it has all of
the features that you need. There is also a demo version of PADS available
on the net, which is the major CAD program used for PCB's. Use a search
engine to find these, or email me.
Ron
- ----------
>From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
>To: "sound@lists.io.com" <sound@lists.io.com>
>Subject: [JN] PCB layout software
>Date: Mon, Sep 18, 2000, 7:39 PM
>
> Guys..
>
> I would like to know if any of you happens to know of a program the is
> cheap and good for PCB layout.
> I would prefer one that also do schematics , and allows to import then
> into the PCB
> layout part.
>
> And if it happens to do tubes , I would LOVE it :-)
>
> - Kurt ( Tired of the old software I have now , and so is my Pentium )
>
>
=========================================================================
From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
Subject: [JN] PCB layout software
Date: Tue, 19 Sep 2000 01:39:56 +0200
Source: Sound Digest Archive v02.n666
Guys..
I would like to know if any of you happens to know of a program the is
cheap and good for PCB layout.
I would prefer one that also do schematics , and allows to import then
into the PCB
layout part.
And if it happens to do tubes , I would LOVE it :-)
- - Kurt ( Tired of the old software I have now , and so is my Pentium )
=========================================================================
From: "Hugh R. Dean" <aksa1@optushome.com.au>
Subject: Re: [JN] PCB layout software
Date: Tue, 19 Sep 2000 12:50:19 +1000
Source: Sound Digest Archive v02.n666
Hi Kurt,
Do you use Protel?
I use version 1.12 for Windows, which was first released in 1991.
It cannot import schematics, but does have a schematics program built in.
This sort of feature did not arrive in the cheaper versions until about
1995, I understand.
What sort of boards do you do? Single, double or multiple layers?
Cheers,
Hugh R. Dean
Research/Technical
www.printedelectronics.com
Melbourne, Australia
=========================================================================
From: "Paul Croft" <pcroft@iximd.com>
Subject: RE: [JN] PCB layout software
Date: Tue, 19 Sep 2000 07:53:31 -0400
Source: Sound Digest Archive v02.n667
Hi Kurt,
You might check out "Assist". Ron Welborne has a good description of it in
his catalog. It's only $50.00 and the catalog is downloadable from Welborne
Labs at www.welbornelabs.com.
Cheers,
Paul
> -----Original Message-----
> From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
> Behalf Of Kurt Steffensen
> Sent: Monday, September 18, 2000 7:40 PM
> To: sound@lists.io.com
> Subject: [JN] PCB layout software
>
>
> Guys..
>
> I would like to know if any of you happens to know of a program the is
> cheap and good for PCB layout.
> I would prefer one that also do schematics , and allows to import then
> into the PCB
> layout part.
>
> And if it happens to do tubes , I would LOVE it :-)
>
> - Kurt ( Tired of the old software I have now , and so is my Pentium )
>
>
=========================================================================
From: "Russ Arbuthnot" <ru55@usa.net>
Subject: Re: [JN] PCB layout software
Date: Tue, 19 Sep 2000 12:57:12 -0500
Source: Sound Digest Archive v02.n667
I just downloaded Circad at www.holophase.com a few weeks ago. It looks
pretty good, but I haven't had a whole lot of time to check it out yet.
Russ
- ----- Original Message -----
From: "Ron & Tamara" <ron.steinberg@sympatico.ca>
To: "Kurt Steffensen" <kurt-steffensen@teliamail.dk>; <sound@lists.io.com>
Sent: Monday, September 18, 2000 8:54 PM
Subject: Re: [JN] PCB layout software
> Kurt,
> Try EagleCad, can't remember the web site but they have a freeware version
> that will do boards up to about 3x4 inches double sided, and it has all of
> the features that you need. There is also a demo version of PADS available
> on the net, which is the major CAD program used for PCB's. Use a search
> engine to find these, or email me.
> Ron
>
> ----------
> >From: Kurt Steffensen <kurt-steffensen@teliamail.dk>
> >To: "sound@lists.io.com" <sound@lists.io.com>
> >Subject: [JN] PCB layout software
> >Date: Mon, Sep 18, 2000, 7:39 PM
> >
>
> > Guys..
> >
> > I would like to know if any of you happens to know of a program the is
> > cheap and good for PCB layout.
> > I would prefer one that also do schematics , and allows to import then
> > into the PCB
> > layout part.
> >
> > And if it happens to do tubes , I would LOVE it :-)
> >
> > - Kurt ( Tired of the old software I have now , and so is my Pentium )
> >
> >
=========================================================================
From: "Dale Simon-contr" <Dale.Simon-contr@trw.com>
Subject: [JN] pcb prototypes
Date: Wed, 01 Aug 2001 08:49:01 -0400
Source: Sound Digest Archive v02.n938
for those of you looking for cheap pcp prototyping, I saw that advanced circuits is offering to do t
wo double layer pcbs for $33. More details are at www.4pcb.com/33each.
Dale
I am in no way affiliated with the above.
=========================================================================
From: "Hugh R. Dean" <aksa1@optushome.com.au>
Subject: [JN] PCBs & Cancer
Date: Tue, 19 Sep 2000 13:47:30 +1000
Source: Sound Digest Archive v02.n667
Hi Folks,
There may be confusion here between pcbs (printed type) and PCBs
(polychloriated biphenyls, a ring organo-choride compound used for many
years in transformer manufacturer and as far as I know by aviation
signwriters as smoke.
pcbs cause irritation because they are epoxy based, and after long exposure,
liver spots on the hands. This would tend to indicate there is the
possibility of carcinogenesis, and there is no doubt vinyl choride monomer
is instrumental in causing angiosarcoma (liver cancer) after about 20 years
exposure, but at this stage little causal evidence to suppose epoxy resin do
the same, although the dust could be implicated in silicosis.
PCBs, on the other hand, are absolute dynamite, as are many of the aromatic
chlorinated substances, such as DDT; 2,4 D; 2,4,5T; Dieldrin, Malathion,
most of the defoliants, and all of the organo phosphates, etc. Rachel
Carson's 'Silent Spring', written in the mid-sixties, alerted the world to
many of these substances. Many of these are now strictly banned by the FDA.
All are very stable, bond readily with organic substances and ecospheres,
and because they are not naturally occurring, have strange effects on the
body, chiefly affecting cell metabolism and the nervous system.
Cheers,
Hugh
Hugh R. Dean
www.printedelectronics.com
Melbourne AUSTRALIA
=========================================================================
From: TubeGarden@aol.com
Subject: Re: [JN] PCBs cause cancer!
Date: Mon, 18 Sep 2000 20:06:12 EDT
Source: Sound Digest Archive v02.n666
In a message dated 9/18/00 4:49:26 PM US Mountain Standard Time,
kurt-steffensen@teliamail.dk writes:
> good for PCB
Greets Kurt!
Wire we Hear!
Happy Ears!
Al B^}
=========================================================================
From: KevinC927@aol.com
Subject: Re: [JN] PCBs cause cancer!
Date: Mon, 18 Sep 2000 20:32:15 EDT
Source: Sound Digest Archive v02.n666
No direct causal link has been established between PCBs and cancer. Relax!
Kevin
=========================================================================
From: Francois Yves Le Gal <flegal@free.fr>
Subject: Re: [JN] PCBs cause cancer!
Date: Tue, 19 Sep 2000 03:04:24 +0200
Source: Sound Digest Archive v02.n666
At 20:32 18/09/00 -0400, KevinC927@aol.com wrote:
>No direct causal link has been established between PCBs and cancer. Relax!
Not between PCB and anything, but between PCB byproducts and cancer, for
sure. Decomposing PCB gives dioxin. Do you remember the Seveso incident?
Need I say more? PCB is a wonderful isolator in transformers or capacitors,
but it's also a *very* dangerous product that should be taken care of
according to proper procedures.
=========================================================================
From: "Vernon Brown" <vhbhifilst@capecod.net>
Subject: RE: [JN] PCBs cause cancer!
Date: Mon, 18 Sep 2000 22:02:12 -0400
Source: Sound Digest Archive v02.n667
Evidentlly, the EPA disagrees:
"PCBs have been demonstrated to cause a variety of adverse health effects.
PCBs have been shown to cause cancer in animals. PCBs have also been shown
to cause a number of serious noncancer health effects in animals, including
effects on the immune system, reproductive system, nervous system, and
endocrine system. Studies in humans provide supportive evidence for
potential carcinogenic and non-carcinogenic effects of PCBs. The different
health effects of PCBs may be interrelated, as alterations in one system may
have significant implications for the other systems of the body. The
potential health effects of PCB exposure are discussed in greater detail
below."
http://www.epa.gov/opptintr/pcb/effects.htm
I know I wash my hands thoroughly after spending an afternoon pawing through
boxes in a surplus electronics warehouse.
Regards,
Sandy Brown
> -----Original Message-----
> From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
> Behalf Of KevinC927@aol.com
> Sent: Monday, September 18, 2000 8:32 PM
> To: sound@io.com
> Subject: Re: [JN] PCBs cause cancer!
>
>
> No direct causal link has been established between PCBs and
> cancer. Relax!
>
> Kevin
>
>
=========================================================================
From: Neil Brown <neilb@telalink.net>
Subject: Re: [JN] PCBs cause cancer!
Date: Tue, 19 Sep 2000 06:46:19 -0500
Source: Sound Digest Archive v02.n667
on 9/18/00 9:02 PM, Vernon Brown at vhbhifilst@capecod.net wrote:
> Evidentlly, the EPA disagrees:
>
> "PCBs have been demonstrated to cause a variety of adverse health effects.
> PCBs have been shown to cause cancer in animals. PCBs have also been shown
> to cause a number of serious noncancer health effects in animals, including
> effects on the immune system, reproductive system, nervous system, and
> endocrine system. Studies in humans provide supportive evidence for
> potential carcinogenic and non-carcinogenic effects of PCBs. The different
> health effects of PCBs may be interrelated, as alterations in one system may
> have significant implications for the other systems of the body. The
> potential health effects of PCB exposure are discussed in greater detail
> below."
>
> http://www.epa.gov/opptintr/pcb/effects.htm
>
> I know I wash my hands thoroughly after spending an afternoon pawing through
> boxes in a surplus electronics warehouse.
>
> Regards,
> Sandy Brown
>
>
>> -----Original Message-----
>> From: owner-sound@lists.io.com [mailto:owner-sound@lists.io.com]On
>> Behalf Of KevinC927@aol.com
>> Sent: Monday, September 18, 2000 8:32 PM
>> To: sound@io.com
>> Subject: Re: [JN] PCBs cause cancer!
>>
>>
>> No direct causal link has been established between PCBs and
>> cancer. Relax!
>>
>> Kevin
>>
>>
>
Fortunbately a "Printed Circuit Board"is not even a close relative to a PCB
of the chemical variety.
polychloriated biphenyls (the chemical) is toxic as heck and a carcinogen
without a doubt. A printed circuit board was made of phenolic or nowadays
fibreglass with copper film glued to it! small fibreglass particles can be
annoying things and may even have the same irritant effect on your lungs as
asbestos, but fear not.. they are not cancer causing.
When I was a kid 25 years ago I used to have a great time cutting oil can
type caps apart and unrolling them. I wonder now how many were PCB type oil
filled?
regards
Neil
=========================================================================
From: "Stewart Ono" <audiodir@gte.net>
Subject: [JN] Re: PCB's: CDR's
Date: Mon, 11 Sep 2000 19:37:46 -1000
Source: Sound Digest Archive v02.n658
I find that the use of PCB for power amplifiers generally leads to problems
down the road, particularly if you are running voltages in excess of about
400V. Traces will arc due to airborne contamination (traffic dust and salt
air) and reliability is reduced in this way. I believe some of the major
problems with the reliability of Audio Research products are due to the use
of the circuit board and the double sided nature of many of their boards. If
the boards are uncoated then the contamination after a few years can
actually arc through the board thickness, at least in areas of high humidity
where contaminants can leach through the uncoated fiberglass.
Point to point wiring sounds and works the best.
I've noticed that whenever I through my CD data into the hard drive the
resulting copy is phase inverted to the original. Also copying at real time
sounds better with cleaner transients. All my copies have better dynamics
and transients than the originals, once phase is corrected for.
Stu
=========================================================================
From: John Levreault <jlevro@mediaone.net>
Subject: Re: [JN] Re: PCB's: CDR's
Date: Tue, 12 Sep 2000 08:14:48 -0400
Source: Sound Digest Archive v02.n659
Stewart Ono wrote:
>
> I believe some of the major
> problems with the reliability of Audio Research products are due to the use
> of the circuit board and the double sided nature of many of their boards. If
> the boards are uncoated then the contamination after a few years can
> actually arc through the board thickness, at least in areas of high humidity
> where contaminants can leach through the uncoated fiberglass.
Absolutely. A friend of mine is a long-time Audio Research owner, with a
preamp, active crossover, and several of their amps. I've had the
opportunity to look "under the hood", and the circuit boards are all
discolored, apparently from overtemperature operation.
JL
=========================================================================
From: darmah@goodnet.com
Subject: [JN] PCB's my method
Date: Thu, 21 Sep 2000 12:58:28 -0700
Source: Sound Digest Archive v02.n668
The big problem with PCB art is getting it into GERBER format so
the PC house photo plotter can read the data.
There's not necessarily any need for expensive PCB software.
Here's the method I use:
The art for the board is created in CAD. I use GEN CAD (One of
the BEST programs ever written) or Visual Cad 3. Autocad works
fine as well but it's cumbersome.
You do need to create items like pads and such as components.
Once the art is done it needs to exported to DXF format. Not a
problem except the the line width,read trace width information gets
lost.
And now comes the BIG trick:
There's this guy who wrote a WONDERFUL conversion utility
program specifically to convert DXF files into Gerber Data called
GERBCON. You can download it from the net.
This takes the the DXF in and creates all the data needed for
GERBER. Drill file is created off the inner diameter of the pads in
question. Line widths,again read trace widths are assigned
according to color. So just make all your .040 traces or what ever
red and during the conversion this color is translated to .040 width
lines and so on.
GERBCON allows multiple layers, silk layer, solder mask if you
like and as I mentioned creates the drill tape layer as well. I can't
say enough about how great this little program is. My copy is
backed up several different places.
It's also wise to get ahold of an older version of CAMTASTIC 99.
This allows viewing of GERBER data. On the older versions this
function remained "free" after the 45 day evaluataion. CAMTASTIC
will allow you to see if your conversion was performed as expected
and since it thinks exactly like a photo plotter you can catch little
things you may have missed in cad.
The beauty of the above is that aside from the CAD program
needed the other two programs are essentially FREE!!!!!
Have you checked the price on even the cheap GERBER
converters lately?
Besides any decent cad program allows far greater flexibility than
most PCB programs. I'll admit the above takes a little learning but I
think it's well worth the effort.
Now of course the easiest way to get one off PCB's would have to
be the EXPRESS PCB software. Which is free of course but you
have to use their service and you have no GERBER data for use by
any other PCB house.
Best Regards
Marc S. Wauters
darmah@bigfoot.com (If mail bounces from this address please use
darmah@goodnet.com and PLEASE let me know!)
My Lowther Enthusiasts Page:
http://www.goodnet.com/~darmah/lowther/lowther.htm
=========================================================================
From: Anders Blix <anders.blix@tv2.no>
Subject: [JN] PC DSP crosover(was RE: Unities Arrived!!!)
Date: Mon, 7 May 2001 20:29:57 +0200
Source: Sound Digest Archive v02.n880
Hello.
This sounds most interresting.
I am in the beginning of building a DSP corrected system, ant therefore your
mail was really interresting. It sure sounds like your system are able to
play some real music.
But I intended to do things a little different.
First off all I have to finish a lott of unfinished projects before I can go
into real DSP-ing.
I have to build the servobass thing I posted about (heilmotioncoupled dipole
servobass). And I have to finish my planar dipoles. I also have to finish my
power amps ( I'm building some Nelsson Pass A-75's).
But my intention for the DSP is to do the folowing:
Work as a crosover.
Phase correct the system.
The next step is:
Downsample the lowpass and convert it to a PWM signal. This was thought done
in a similar way as the TACT power DAC.
The frequencies used here makes it possible to use a fairly low sampeling
rate. Therefore the I/O should be possible. The thing is that I intend to
feed this PWM signal directly to power switches (big FET's or IGBT's)
directly (or possibly drive them with driver chips to get a fast enoug
switching). I'm not sure how to get this signal from the PC, but a normal
soundcard is probably not the right ting. Then I would have to write my own
drivers and stuff like that, and that would be a bitt to much for me.
But I think it is a good idea. First off all I have heard the TACT, and it
is the cleanest sounding amp I have ever heard (well not able to compare
them directly to the other big fellas I have heard thoug, due to the not so
good speakers in the system I heard). And second the servomotors in a
servobass system is best driven by a switched amp. It is even possible to
use the encoders on the motors (servomotors does normaly have some kind of
fedback devices on them) to do a closed loop system. I have even found a
DIY-card capable of reading the encoders (this is actually made to work with
CNC programs, but I dont se why it cant be used with servobasses).
But then some questions on the DSP-probrams. I have looked at the WaweWarp
software, and it looks impresive. But what is it we actually need of
DSP-ing???? Have you looked at http://www.ludd.luth.se/~torger/brutefir.html
????
Could this possibly be used???? And it is for the time being free to... And
it is on Linux platform, wich is a much more stable system. It is also the
platform I intend to use for my DSP-ing. But it isn't finished yet, so it is
possible we have to wait for a more complete version.
And I think manny more than I would be verry interrested in a web page
describing it in more detail!!!
It's not that hard to write it. The challenge is to putt something really
informative there. But that part I'm sure you are fully capable of. Just
start writing it down in word or another word processor capable of saveing
it as html. Then you just have to find a suitable server to put it on. I'm
sure you can find that.
Anders Blix
> -----Opprinnelig melding-----
> Fra: John Hancock [SMTP:John_Hancock@swissre.com]
> Sendt: 5. april 2001 17:31
> Til: jhsutton@adelphia.net; sndlabmark@aol.com; alexmi@omneon.com;
> peter.sikking@virgin.net
> Kopi: sound@lists.io.com; bass@lists.cc.utexas.edu
> Emne: [JN] RE: Unities Arrived!!!
>
>
>
>
> Sorry for the mass reply. Answers to the various questions below:
>
> 1) My setup is as follows:
>
> Bass: TAD 1602 (extremely low distortion 16" woofer) in 5 cu ft. bass
> reflex cabinet
>
> DSP/Crossover: an Athlon 1200mHz PC running a program called Wave Warp,
> M-Audio Delta 1010 sound card. WaveWarp (www.soundslogical.com) is the
> only
> program I have found that allows you to do "advanced" real time DSP
> (frequency domain filtering, multirate filtering, resampling, etc.). I do
> all my digital filter design using Matlab--this is where the "art" comes
> in. Sound card is a bit of a misnomer for the Delta 1010. It has an
> interface card, but the DAC/ADC is done in an external box. It has 8
> channels of balanced in/out, pro or consumer level setable by a switch,
> everything 96/24. It is low noise (109dB SNR for the DAC) and actually
> sounds pretty good. Not bad for about $600 US. In terms of DSP
> capabilities
> this setup blows away any BSS products. The downside is you have to deal
> with the vagueries of Windows.
>
> Amps: homebuilt VV52 amps on top, generic Adcom amp on the bottom.
>
> 2) The tweeking/DSP process is difficult to explain in a paragraph or two
> and really requires some graphs to explain. I don't want to discourage
> anyone because it's really not rocket science, but there is a substantial
> amount of playing around to find something that works. I need figure out
> how to make a web site so I can do a proper job of explaining things. One
> day, hopefully soon...
>
> 3) If you can make it to Zurich, you're more than welcome to stop by for a
> listen.
>
> 4) The sound: It's actually easy to describe the sound. It sounds exactly
> like you would expect a speaker with flat frequency response, linear phase
> and almost no distortion--it's the closest to unrecorded music that I have
> ever gotten.
>
> One thing to keep in mind, though, is that these are directional speakers
> and so require a different room setup than omnidirectional speakers. To
> get
> the same level of reverberant sound as you have with your omnidirectional
> speakers, you'll have to take some damping out of the room to make the
> room
> "livelier." This is actually a good thing--for a given level of
> reverberant
> sound, it is better to have directional speakers and a lively room than
> omnidirectional and a dead room. This is because the correlation between
> the direct sound and the reverberant sound is lower with the directional
> speaker/lively room setup.
>
> The stereo image on directional speakers is also often smaller than with
> omnidirectional speakers because you also don't get phantom sources from
> wall reflections, which can make the stereo image actually seem wider than
> the spacing of the speakers. With these speakers the image is as wide as
> the space between the speakers and that is it. The imaging is great with
> these speakers, everything is exactly where it belongs, it's just that you
> get a smaller image without the reflections. You can compensate for this
> by
> moving the speakers farther apart, but there is a limit to how wide you
> can
> space them before the central image starts to fade. You could also try
> aiming the speakers at the walls and just listen to the phantom sources
> (hey it doesn't hurt to try).
>
> Well, I hope that is interesting for someone. Summary of the review: a big
> thumbs up. Thanks very much Tom and Nick. Like I said, I'll try to
> eventually write up the signal processing methods and put it on a website
> with actual measurements of the speakers. Any advice on how to get a web
> site up and running at minimal cost?
>
> John
>
=========================================================================
From: "Jarkko K. Laukkanen" <jklaukka@pcu.helsinki.fi>
Subject: [JN] PCM1732 Datasheet
Date: Mon, 20 Aug 2001 09:47:50 +0300 (EET DST)
Source: Sound Digest Archive v02.n950
Group,
I have it, and I already sent it to Remco. If anyone else needs it, e-mail me
privately off the list.
- - --
Jarkko K. Laukkanen, Ph.D.
X-Ray Laboratory, Dept. of Physics, Univ. of Helsinki, Finland.
WWW: http://www.physics.helsinki.fi/~jklaukka/
"That may be true," he acknowledged, "but it's completely
accurate, and as long as the answer is right, who cares if
the question is wrong? If you want sense, you'll have to
make it yourself."
'The Phantom Tollbooth' by Norton Juster
=========================================================================
From: John Niven <jn@cypress.com>
Subject: [JN] PCM-501es
Date: Tue, 30 Jan 2001 13:41:54 -0800
Source: Sound Digest Archive v02.n795
I've just seen a Sony PCM-501es for $40 at my local charity shop.
Looks like some kind of digital recorder to me, but I don't know
anything else.
It lights-up with power, but that's all I'm going to be able to find out
about it.
Anybody know what it is?
Should I snap it up?
Cheers,
John
=========================================================================
From: David Barnett <d_n_b@swbell.net>
Subject: Re: [JN] PCM-501es
Date: Tue, 30 Jan 2001 17:47:37 -0600
Source: Sound Digest Archive v02.n796
On Tue, 30 Jan 2001 13:41:54 -0800, John Niven <jn@cypress.com> wrote:
>I've just seen a Sony PCM-501es for $40 at my local charity shop.
>
>Looks like some kind of digital recorder to me, but I don't know
>anything else.
This is one of several gadgets that Sony made for recording PCM audio
onto video tape. You use it with a VCR, which serves as a tape
transport for the PCM-501, which contains the audio circuitry and
a/d--->d/a converters.
I think it's well worth $40, even if just for laughs.
- --dnb
=========================================================================
From: "Remco Stoutjesdijk" <r.m.stoutjesdijk@student.utwente.nl>
Subject: RE: [JN] PCM-501es
Date: Wed, 31 Jan 2001 16:24:01 +0100
Source: Sound Digest Archive v02.n796
> Anybody know what it is?
>
> Should I snap it up?
These are the units that gave digital a bad name, the first digitizers of
the '80s were lousy.
Would be nice as relic though- the beginning of the end... ;)
Regards,
Remco
- --
http://listen.to/rmsaudio
=========================================================================
From: John Niven <jn@cypress.com>
Subject: Re: [JN] PCM-501es
Date: Thu, 01 Feb 2001 18:04:07 -0800
Source: Sound Digest Archive v02.n797
Thanks for the info on this unit. I did not buy it - somebody else
snapped it up anyway! The one for sale on Ebay went for $113, so I guess
I could have made a profit if I had bought it at the asked $40. Oh well
too much trouble anyway.
Cheers,
John
Remco Stoutjesdijk wrote:
>
> > Anybody know what it is?
> >
> > Should I snap it up?
>
> These are the units that gave digital a bad name, the first digitizers of
> the '80s were lousy.
>
> Would be nice as relic though- the beginning of the end... ;)
>
> Regards,
> Remco
> --
> http://listen.to/rmsaudio
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: [JN] PC Y2K Fix
Date: Fri, 06 Aug 1999 18:52:06 -0700
Source: Sound Digest Archive v02.n227
Hi All,
I received this from number one daughter and thought I would pass it
along just in case some of you are not on your toes. This relates to a
windows date setup and should be done in addition to whatever else is
done to make you computer Y2K compliant. This is probably intuitivly
obvious to most windows gurus, but is something I had not checked, or
even thought about, and I suspect many others have not done so either.
It seems that Microsoft's default date setting is in a mm/dd/yy format.
This should be changed to a mm/dd/yyyy format. This can be done from
the control panel. Below is a blow-by-blow description as I received it
for the windows-challenged, like me.
Also, I have seen various software programs for around thirty bucks that
are supposed to run your computer through its paces and check to see
whether it is Y2K compliant and make the required setting changes and
recommend any required hardware upgrades, if any. Does anyone have
detailed knowledge about or experience with such programs and can
recommend which one is the best one to use?
I'd also like to know what makes my computer so damn slow in Netscape.
That sumbitch will just set there like a dumb-assed mule after you click
on something until it gets damn-well ready to do something, that pisses
me off on a regular basis. You never know whether it has even
recognized the command, then you click again and it saves this second
click and shuts something down entirely, like Netscape, for instance. I
downloaded a $30 buck program that was supposed to fix this. The
promoters claim that Windows/Netscape is shipped optimized for network
operation and the settings must be optimized for best perfortmance for a
stand-alone unit. I never did get it to work, so should go back and
have another go at it I guess.
Dan Marshall
The how-to details.......
Hmm... FYI...
You may think your PC is "Y2K" compliant, and some little tests may
have actually affirmed that your hardware is compliant, and you may even
have a little company sticker affixed to your system saying "Y2K
Compliant"... but you'll be surprised that Windows may still crash
unless you do this simple exercise below. Easy fix but something
Microsoft seems to have missed in certifying their software as Y2K
compliant.
This is simple to do, but VERY important.
- -----------------------------------------
Click on "START".
Click on "SETTINGS".
Double click on "Control Panel".
Double click on "Regional settings" icon (look for the little world
globe).
Click on the "Date" tab at the top of the page. (last tab on the top
right)
Where it says, "Short Date Sample", look and see if it shows a "two
digit" year format ("YY"). Unless you've previously changed it (and you
probably haven't) -- it will be set incorrectly with just the two
Y's..it needs to be four!
That's because Microsoft made the 2 digits setting the default setting
for Windows 95, Windows 98 and NT.
This date format selected is the date that Windows feeds *ALL*
application software and will not rollover into the year 2000. It will
roll over to the year 00. Click on the button across from "Short Date
Style" and select the option that shows, "mm/dd/yyyy" or "m/d/yyyy". (Be
sure your selection has four y's showing, not just "mm/dd/yy).
Then click on "Apply".
Then click on "OK" at the button.
Easy enough to fix. However, every "as distributed" installation of
Windows worldwide is defaulted to fail Y2K rollover... Pass this along
to your PC buddies... no matter how much of a guru they think they
are... this might be a welcome bit of information!
=========================================================================
From: "Daniel J. Marshall" <danmarshall@worldnet.att.net>
Subject: Re: [JN] PC Y2K Fix
Date: Sat, 07 Aug 1999 14:46:46 -0700
Source: Sound Digest Archive v02.n228
Joseph Lowe wrote:
>
> On Fri, 6 Aug 1999, Daniel J. Marshall wrote:
>
> > It seems that Microsoft's default date setting is in a mm/dd/yy format.
> > This should be changed to a mm/dd/yyyy format. This can be done from
> > the control panel. Below is a blow-by-blow description as I received it
> > for the windows-challenged, like me.
>
> Not only is this not the proper forum for this, it is bogus information
> which is becoming urban legend. Please check Dejanews
> (comp.software.year-2000) for a complete discussion of this, and why it
> is nothing more than a band-aid that simply covers up the underlying
> problems. If you think this is all that is required to fix all your PC Y2K
> problems, you are in for a rude awakening come the new year.
>
>
I believe I made that perfectly clear in the original post when I said
that this is a little thing you need to do in addition to whatever else
is done to make the computer Y2K compliant.
Dan Marshall
=========================================================================
From: Joseph Lowe <jlowe@cdc.net>
Subject: Re: [JN] PC Y2K Fix
Date: Sat, 7 Aug 1999 17:08:44 -0400 (EDT)
Source: Sound Digest Archive v02.n228
On Fri, 6 Aug 1999, Daniel J. Marshall wrote:
> It seems that Microsoft's default date setting is in a mm/dd/yy format.
> This should be changed to a mm/dd/yyyy format. This can be done from
> the control panel. Below is a blow-by-blow description as I received it
> for the windows-challenged, like me.
Not only is this not the proper forum for this, it is bogus information
which is becoming urban legend. Please check Dejanews
(comp.software.year-2000) for a complete discussion of this, and why it
is nothing more than a band-aid that simply covers up the underlying
problems. If you think this is all that is required to fix all your PC Y2K
problems, you are in for a rude awakening come the new year.
=========================================================================
From: "Bill Gaw" <whg@tiac.net>
Subject: Re: [JN] PC Y2K Fix
Date: Sun, 8 Aug 1999 08:47:05 -0400
Source: Sound Digest Archive v02.n228
Yes, it was perfectly clear, and I'm sure it helped. Thanks. Bill
- -----Original Message-----
From: Daniel J. Marshall <danmarshall@worldnet.att.net>
To: Joseph Lowe <jlowe@cdc.net>
Cc: <sound@deliverator.io.com>
Date: Saturday, August 07, 1999 6:07 PM
Subject: Re: [JN] PC Y2K Fix
>Joseph Lowe wrote:
>>
>> On Fri, 6 Aug 1999, Daniel J. Marshall wrote:
>>
>> > It seems that Microsoft's default date setting is in a mm/dd/yy format.
>> > This should be changed to a mm/dd/yyyy format. This can be done from
>> > the control panel. Below is a blow-by-blow description as I received
it
>> > for the windows-challenged, like me.
>>
>> Not only is this not the proper forum for this, it is bogus information
>> which is becoming urban legend. Please check Dejanews
>> (comp.software.year-2000) for a complete discussion of this, and why it
>> is nothing more than a band-aid that simply covers up the underlying
>> problems. If you think this is all that is required to fix all your PC
Y2K
>> problems, you are in for a rude awakening come the new year.
>>
>>
>
>I believe I made that perfectly clear in the original post when I said
>that this is a little thing you need to do in addition to whatever else
>is done to make the computer Y2K compliant.
>
>Dan Marshall
>
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] PC Y2K Fix
Date: Sun, 08 Aug 1999 14:59:13 +0200
Source: Sound Digest Archive v02.n229
>If you think this is all that is required to fix all your PC Y2K
>problems, you are in for a rude awakening come the new year.
despite of the champagne ?
Guido
>
>
>
>
>
>
=========================================================================
From: Remco Stoutjesdijk <remco@ultranalog.com>
Subject: [JN] pdf's available
Date: Tue, 21 Aug 2001 13:21:46 +0200
Source: Sound Digest Archive v02.n951
Hi,
I finally managed to convert the micros~1 files to .pdf and keep them relatively small as well (1st
version was 6.7 MB).
Class-D lecture:
http://www.ultranalog.com/el/classD.pdf (220 kB)
Jitter in sigma/delta converters sublecture:
http://www.ultranalog.com/el/Jitter_SD.pdf (1.5 MB)
(mind the caps - the machine is case sensitive)
The equi-Q picture has the font screwed up. The axes should read Nb (number of bits), Fs (sampling f
req) and modulator order. Then the plane is an equi-Q plane.
Slide notes aren't available yet, as I tend not to make them but just make things up as I go along.
In coop with Guido and Manfred, I'll provide more complete versions later (don't pin me down) on.
In addition to the classD, the Cuk paper is still available:
http://www.ultranalog.com/el/cuk.pdf (1.1 MB)
Readability is not so good, but this is the way I got it.
Ciao,
Remco
- --
http://www.ultranalog.com
=========================================================================
From: "Ian McPhail" <i.mcphail@rmit.EDU.AU>
Subject: [JN] re: pdf VALVE
Date: Tue, 2 Feb 1999 09:43:14 +1000
Source: Sound Digest Archive v02.n020
No problems here downloading and printing the .pdf VALVE. Looks
as good as the original hard copy and I don't have to wait on the air
mail to Oz.
regards Ian
Ian McPhail i.mcphail@rmit.edu.au
RMIT Chem and Met Eng Dept 110
GPO Box 2476V
Melbourne 3001
Australia
tel +61 3 9925 2408
fax +61 3 9925 3746
=========================================================================
From: evaguido <EvaGuido@iaehv.nl>
Subject: Re: [JN] re: pdf VALVE
Date: Thu, 04 Feb 1999 19:57:58 +0100
Source: Sound Digest Archive v02.n028
Most computers / printers take little more time printing .PDF files
No furthers problems at this side
Guido
At 09:43 2-2-99 +1000, Ian McPhail wrote:
>No problems here downloading and printing the .pdf VALVE. Looks
>as good as the original hard copy and I don't have to wait on the air
>mail to Oz.
>regards Ian
>
> Ian McPhail i.mcphail@rmit.edu.au
> RMIT Chem and Met Eng Dept 110
> GPO Box 2476V
> Melbourne 3001
> Australia
> tel +61 3 9925 2408
> fax +61 3 9925 3746
>
>
=========================================================================
From: Steve Van Osdell <svanos@queencity.com>
Subject: [JN] Peace
Date: Wed, 12 Sep 2001 09:05:03 -0400
Source: Sound Digest Archive v02.n965
"We cannot have peace until we can love our children more than we hate
our enemy" - Golda Meir
=========================================================================
From: Steve Van Osdell <svanos@queencity.com>
Subject: Re: [JN] Peace
Date: Wed, 12 Sep 2001 10:13:08 -0400
Source: Sound Digest Archive v02.n965
I posted this meaningful passage from Golda Meir and purposefully modified
it slightly so as not to offend anyone and so that it could be taken as a
general message good for everyone to apply. Now I am getting messages
like the following lambasting me with presumptiveness and cloaked
accusations for my 'motives' behind modifying the quotation. Why are so
many people on this list afflicted with the attitude that they can know
what is in someone else's thoughts? I've never seen a group with a higher
percentage of people who want to 'twist around' what some other person
(who they don't even know) thinks. We are truly in 'deep shit' if a
person can't even speak without such venom and prejudice pouring out. I'm
amazed at all the narrowmindedness here. And I apologize for modifying
the quote to what I thought would be a more less offensive and benign
form. The meaning, I thought, was still universally intact.
>>That's totally twisted around... the original..
"We will have peace when the arabs love their children more than they hate
us."
but hey we all know your views
>>>>
Steve Van Osdell wrote:
> "We cannot have peace until we can love our children more than we hate
> our enemy" - Golda Meir
=========================================================================
From: "Phil Sieg" <triodelover@home.com>
Subject: Re: [JN] Peace
Date: Wed, 12 Sep 2001 10:44:36 -0400
Source: Sound Digest Archive v02.n965
>Why are so
> many people on this list afflicted with the attitude that they can know
> what is in someone else's thoughts?
Maybe because you've revealed to us some of your less pretty thoughts in the
past? Having a handle on where you're coming from makes it awfully tempting
to consider all similar posts as springing from the same motives. 'Tis
unfair to be sure, but it's human nature.
Phil
=========================================================================
From: ken gilbert <ride5000@ride.ri.net>
Subject: Re: [JN] Peace
Date: Wed, 12 Sep 2001 13:21:10 -0400
Source: Sound Digest Archive v02.n965
>I posted this meaningful passage from Golda Meir and purposefully modified
>it slightly so as not to offend anyone and so that it could be taken as a
>general message good for everyone to apply.
Steve, I don't know you from a hole in the wall, but I DO know that when
one uses quotation marks it implies--nay, MANDATES even--that the EXACT
WORDS were used by the individual that the quote was attributed to. If you
paraphrase someone, you don't use quotes; if you modify a passage slightly,
whatever the purpose may be, you don't use quotes.
This is not "narrowmindedness" (note my use of quotes here to indicate the
word can be attributed directly to you) but proper use of punctuation so as
to promote clarity and prevent ambiguity.
Hopefully you will not interpret this message as yet another display of
"venom and prejudice." I have none of that. Rather, I have only a
Bachelor's degree in English.
Ken Gilbert
=========================================================================
From: Alex Shaltiel <shalt@paradigmgeo.com>
Subject: RE: [JN] Peace
Date: Wed, 12 Sep 2001 17:03:52 +0200
Source: Sound Digest Archive v02.n965
That's totally twisted around... the original..
"We will have peace when the arabs love their children more than they hate
us."
but hey we all know your views
http://news.bbc.co.uk/hi/english/talking_point/newsid_1482000/1482676.stm
> -----Original Message-----
> From: Steve Van Osdell [mailto:svanos@queencity.com]
> Sent: Wednesday, September 12, 2001 3:05 PM
> To: Joe List
> Subject: [JN] Peace
>
>
> "We cannot have peace until we can love our children more than we hate
> our enemy" - Golda Meir
>
=========================================================================
From: "PEARL Cust Serv" <custserv@pearl-hifi.com>
Subject: [JN] PEARL Audio Notes
Date: Fri, 21 Apr 2000 17:36:58 -0600
Source: Sound Digest Archive v02.n526
Hello All:
Most embarrassing . . . . one of you good Joes sent money for a copy of
my "Audio Notes" and although I now have the item ready to ship, I have
somehow managed to loose/misplace your address.
Please mail me so I can ship to you . . .
Thanks . .
Best regards,
Bill - PEARL, Inc.
I can hardly wait for the dinosaurs to die off . . . . again !
=========================================================================
From: "PEARL Cust. Service" <custserv@pearl-hifi.com>
Subject: Re: [JN] PEARL OPTs have been sold
Date: Thu, 31 May 2001 13:55:18 -0600
Source: Sound Digest Archive v02.n896
Andrej D Wrote:
SNIP
> I shall keep the document about these OPT on-line for a few more days if
> anyone wants to read it.
>
> Andrej Deticek
If any of you downloaded that PDF immediately after Andrej made it
available it's worth you while to go and get it again as I spotted a typo in
it that had been there for a long time but which neither I nor anyone else in
the last several years had noticed or commented on.
Mistakenly, I said, "Class A" when what I meant to say was, "Class AB" and
that error made nonsense of the rest of the paper.
Bill Perkins - PEARL, Inc.
=========================================================================
From: Andrej Deticek <andrej.deticek@amis.net>
Subject: [JN] PEARL OPTs have been sold
Date: Thu, 31 May 2001 21:17:09 +0200
Source: Sound Digest Archive v02.n896
The PEARL 280WOPTs I advertised a few days ago, have been sold.
I shall keep the document about these OPT on-line for a few more days if
anyone wants to read it.
Andrej Deticek
=========================================================================
From: "Epstein, Jeremy" <JEpstein@ndbcap.com>
Subject: [JN] Peerless 4722 (plug-in mic transformers) - anybody want to sell s ome?
Date: Tue, 31 Jul 2001 16:53:57 -0400
Source: Sound Digest Archive v02.n938
I'd like to try a pair as MC step-ups - anybody have a pair they'd like to
part with?
Rick?
- -j
=========================================
Jeremy Epstein........jepstein@ndbcap.com
=========================================
=========================================================================
From: "Phil Sieg" <triodelover@home.com>
Subject: Re: [JN] Peerless 4722 (plug-in mic transformers) - anybody want to sell some?
Date: Tue, 31 Jul 2001 18:01:13 -0400
Source: Sound Digest Archive v02.n938
j,
I have one, having picked up three (???) off eBay a while back. If you can
find another, you can have mine ( hey, I owe you for the Martzy) to pair
with it. Specs, if you don't have them, are 38/150:15K. You might also
consider the Peerless 15095. It can be configured 150:15k for a 1:10
step-up. Both show up on eBay every now and then. Both units (according to
Mikey) have Permalloy (50% Ni) cores.
Phil
- ----- Original Message -----
From: "Epstein, Jeremy" <JEpstein@ndbcap.com>
To: "Joenet (E-mail)" <sound@lists.io.com>
Sent: Tuesday, 31 July, 2001 16.53
Subject: [JN] Peerless 4722 (plug-in mic transformers) - anybody want to
sell some?
> I'd like to try a pair as MC step-ups - anybody have a pair they'd like to
> part with?
>
> Rick?
>
> -j
>
> =========================================
> Jeremy Epstein........jepstein@ndbcap.com
> =========================================
>
=========================================================================
From: "PEARL Cust Serv" <custserv@pearl-hifi.com>
Subject: [JN] Peerless PTs & Chokes on eBay
Date: Sun, 17 Sep 2000 11:30:32 -0600
Source: Sound Digest Archive v02.n665
Hi All:
It's shameless self-promotion time again: . . . :)
http://cgi.ebay.com/aw-cgi/eBayISAPI.dll?ViewItem&item=439772587
As there are no bids yet, I can still pull this auction if anyone wants
to buy these directly . . . .
Bill - PEARL, Inc.
- -----------------------------------
1 pair of each of Peerless power transformer and choke. These are
tar-potted in mild steel cans that still bear the original paint. One choke
however has a few chips in the paint and some of these have rusted slightly.
The power trans has a 0 - 105 - 115 - 125, 50/60Hz primary.
The secondaries are:
* 6.3V @ 6A
* 5.0V @ 4A
* 700 - 0 - 700 with a 0 - 140 bias tap.
* 660 - 0 - 660 at a full load current of 200mA
The choke is rated at 5 Henries @ 250mADC it will support a 300mDC
current if a 10uF cap in series with a 47ohm resistor is placed to ground on
its input side. This also improves the regulation and the transient
performance.
=========================================================================
From: "Alex Rubli K." <rubli@noc.pue.udlap.mx>
Subject: [JN] pen
Date: Wed, 10 Mar 1999 18:03:25 -0600 (CST)
Source: Sound Digest Archive v02.n071
Hi dear audio-fellows.
not a rigorously audio question.
I have lots of tubes that I am testing, and would like to write on the
tubes, lets say the gain, or if the original letters are worn out, or
just about to.
is there a pen or some gizmo where I can write directly to glass and
it won't fall off ? (needles to say, even with heat)
I have tried several brands of permanent markers, but no good.
thanx in advance for soembody comming with a hint on this.
regards
alex rubli
------------==========-------____\|/___-------==========------------
| Alexander Rubli K. Universidad de las Americas,Puebla |
| Rubli@mail.udlap.mx Sta. Catarina Martir |
| rubli@pobox.com Cholula,72820 Puebla |
| vox:(52) (22) 29-2158 FAX:(52) (22) 29-2140 MEXICO |
| URL: http://noc.pue.udlap.mx/eno/Arubli.shtml "" "" |
| ----------------------------------------- - O |
| Honour thy errors as a hidden intention (B. Eno) I |
------------==========_______----/|\----_______==========---- ~.
=========================================================================
From: "Michael Cameron" <mncameron@worldnet.att.net>
Subject: Re: [JN] pen
Date: Wed, 10 Mar 1999 18:12:09 -0800
Source: Sound Digest Archive v02.n071
Alex
Sharpie Marking Pens work just fine for me for marking tubes. Seems to last
well for all but the hottest running tubes.
Michael
- -----Original Message-----
From: Alex Rubli K. <rubli@noc.pue.udlap.mx>
To: sound@lists.io.com <sound@lists.io.com>
Date: Wednesday, March 10, 1999 4:16 PM
Subject: [JN] pen
>
>Hi dear audio-fellows.
>
>not a rigorously audio question.
>
>I have lots of tubes that I am testing, and would like to write on the
>tubes, lets say the gain, or if the original letters are worn out, or
>just about to.
>
>is there a pen or some gizmo where I can write directly to glass and
>it won't fall off ? (needles to say, even with heat)
>
>I have tried several brands of permanent markers, but no good.
>
>thanx in advance for soembody comming with a hint on this.
>
>regards
>
>alex rubli
>
> ------------==========-------____\|/___-------==========------------
>| Alexander Rubli K. Universidad de las Americas,Puebla |
>| Rubli@mail.udlap.mx Sta. Catarina Martir |
>| rubli@pobox.com Cholula,72820 Puebla |
>| vox:(52) (22) 29-2158 FAX:(52) (22) 29-2140 MEXICO |
>| URL: http://noc.pue.udlap.mx/eno/Arubli.shtml "" "" |
>| ----------------------------------------- - O |
>| Honour thy errors as a hidden intention (B. Eno) I |
> ------------==========_______----/|\----_______==========---- ~.
>
>
=========================================================================
From: rbales@gte.net (Ron Bales)
Subject: Re: [JN] pen
Date: Thu, 11 Mar 1999 01:59:59 GMT
Source: Sound Digest Archive v02.n071
In the US we have a permanent marker sold by the name of "Sharpie"
this is the one you want. They come in several widths the fine and
ultra-fine models both have uses in this hobby.
I don't recall seeing them in Mexico, but if needed I can arrange to
swap you a box. They are essential.
ROn
On Wed, 10 Mar 1999 18:03:25 -0600 (CST), you wrote:
>
>Hi dear audio-fellows.
>
>not a rigorously audio question.
>
>I have lots of tubes that I am testing, and would like to write on the
>tubes, lets say the gain, or if the original letters are worn out, or
>just about to.
>
>is there a pen or some gizmo where I can write directly to glass and
>it won't fall off ? (needles to say, even with heat)
>
>I have tried several brands of permanent markers, but no good.
>
>thanx in advance for soembody comming with a hint on this.
>
>regards
>
>alex rubli
>
> ------------==========-------____\|/___-------==========------------
>| Alexander Rubli K. Universidad de las Americas,Puebla |
>| Rubli@mail.udlap.mx Sta. Catarina Martir |
>| rubli@pobox.com Cholula,72820 Puebla |
>| vox:(52) (22) 29-2158 FAX:(52) (22) 29-2140 MEXICO |
>| URL: http://noc.pue.udlap.mx/eno/Arubli.shtml "" "" |
>| ----------------------------------------- - O |
>| Honour thy errors as a hidden intention (B. Eno) I |
> ------------==========_______----/|\----_______==========---- ~.
>
=========================================================================
From: Ted.Riesz@isr.gov.au
Subject: RE: [JN] pen
Date: Thu, 11 Mar 1999 11:49:53 +1100
Source: Sound Digest Archive v02.n071
Alex
I have used my wife's clothing marker pen (ie used to mark childrens
clothes) to good effect. Does no seem to rub off.
Regards
Ted Riesz
=========================================================================
From: rcjones1@mmm.com
Subject: [JN] Pentode cathode followers.
Date: Tue, 10 Apr 2001 09:58:11 -0500
Source: Sound Digest Archive v02.n862
Hey!
I am trying to build a pentode cathode follower. The pentode is connected
so that it is driven via its screen grid. Its actually a EL509. 162v Ec2.
- -33v grid bias, 125mA cathode current, and 150v operating voltage. There
is some info about this type of connection at the svetlana tube web site.
There will be 1 resistor at the cathode to set grid bias just like at the
web site. It would be a 260ohm resistor. At the bottom of this a constant
current sink of 125mA. The load then would be connected from where these
two meet through a cap to ground.
What is the gain? Zo? and how do I draw load lines for it?
Does this configuration even work? As it would be direct coupled from the
previous stage with a 195v plate voltage (162+33).
Am I way off base here or is this remotely correct?
Thanks!
Richard Jones
=========================================================================
From: "Le Cleac'h Jean-Michel" <lecleach@paris.ensmp.fr>
Subject: Re: [JN] pentode connected as high mu triode
Date: Thu, 10 May 2001 16:10:03 +0200
Source: Sound Digest Archive v02.n882
- -----Message d'origine-----
De : David Crittle <retrovox@bigpond.com>
À : sound@lists.io.com <sound@lists.io.com>
Date : jeudi 10 mai 2001 16:00
Objet : [JN] pentode connected as high mu triode
>The STC Application Report for type 6BW7 (RF and IF pentode, used in TV
>receivers) has curves for an interesting mode of operation: the screen grid
>strapped to the control grid, and the supressor grid strapped to the plate,
>resulting in a very high-mu triode. With a plate voltage of 500 volts, mu
>is 2400!
>I haven't heard of this type of triode connection before. Is it/has it/can
>it ever been used for audio?
>
>I have uploaded curves (three tiff files, each about 70K) to
>http://joelist.free.fr/ in the manufacturer's data folder. I have also
>uploaded the STC application report for type 3A/167M (pdf about 300K)
Here is a reply I have given on Joenet to a post sent by R. Jones
- -----Message d'origine-----
De : rcjones1@mmm.com <rcjones1@mmm.com>
À : sound@lists.io.com <sound@lists.io.com>
Date : mercredi 11 avril 2001 18:20
Objet : [JN] Svetlana's "triode" EL509 curves
>Is it just me or do they list a pentode connection, enhanced triode
>connection, and one where both the control and screen grid are connected
>togethor. I thought a triode connection is just where the control grid is
>the only one driven and the screen grid is connected to the plate via a
>100ohm resistor? or am i mistaken......?
Hello,
Due to the fact that if you want to obtain a quasi triode from a pentode you
may connect 2 of the electrods, it exists several possible connection.
The connection youmention is the usual one.
The remote one connecting the screen to the control grid lead to a triode
generally used a 0 volt bias or with positive grid voltage and in that case
you must consider current grid. (This was used mostly in RF emission)
Best regards,
Jean-Michel Le Cleac'h, Paris, France
=========================================================================
From: thomas.mayer@philips.com
Subject: Re: [JN] pentode connected as high mu triode
Date: Thu, 10 May 2001 16:14:26 +0200
Source: Sound Digest Archive v02.n882
> The STC Application Report for type 6BW7 (RF and IF pentode, used in TV
> receivers) has curves for an interesting mode of operation: the screen grid
> strapped to the control grid, and the supressor grid strapped to the plate,
> resulting in a very high-mu triode. With a plate voltage of 500 volts, mu
> is 2400!
What does this report say about the rp in that mode ?
Thomas
=========================================================================
From: "Le Cleac'h Jean-Michel" <lecleach@paris.ensmp.fr>
Subject: Re: [JN] pentode connected as high mu triode
Date: Thu, 10 May 2001 16:34:01 +0200
Source: Sound Digest Archive v02.n882
- -----Message d'origine-----
De : thomas.mayer@philips.com <thomas.mayer@philips.com>
À : retrovox@bigpond.com <retrovox@bigpond.com>
Cc : sound@lists.io.com <sound@lists.io.com>
Date : jeudi 10 mai 2001 16:25
Objet : Re: [JN] pentode connected as high mu triode
>> The STC Application Report for type 6BW7 (RF and IF pentode, used in TV
>> receivers) has curves for an interesting mode of operation: the screen
grid
>> strapped to the control grid, and the supressor grid strapped to the
plate,
>> resulting in a very high-mu triode. With a plate voltage of 500 volts, mu
>> is 2400!
>
>What does this report say about the rp in that mode ?
Hello,
I cannot say what the report will say about the Rp value in that mode but
before David'll get a look at the report:
- - from memory :
the Rp value in that mode is nearly the same as in the pentode
mode, so this leads to a high mu, high Rp (= low transconductance) triode.
For my own I prefer to drive such tub