[Arny Krueger]

"Eeyore" wrote in
message
Arny Krueger wrote:

"Eeyore" wrote
in
Chris Hornbeck wrote:
Eeyore wrote:

The answer is easily derived from basic principles,
or even from a Google search on this newsgroup. It
ain't rocket surgery.

I just posted my thoughts on the matter.

How about yours ?

A voltage gradient across the cathode is similar to
a geometric gradient in cathode-grid spacing, or
alternatively to a variable grid winding pitch.

That's what I concluded too. Like a variable mu tube
IIRC.

Neither are exact, but give the flavor. The voltage
gradient causes distortion by increasing the
exponent in the Child's approximation.

Yes.

IIRC this may have been discussed in threads
about ultrasonic heating of filamentary valves.
But maybe not.

I hadn't heard that one.

In any event, an audible difference between DC and AC
heating of DHTs indicates to me that with AC there must
be some signal modulation at 2 x line frequency, like a
tiny tremolo effect perhaps.

How can this sonic effect be perceived as improved
realism?

It wouldn't be of course but SETs aren't about realism
anyway.

Agreed - modern SETs are mostly just glorified EFX processors. Think of them
as stomp boxes that are big, expensive, heavy, and run hot. ;-)

[Chris Hornbeck]

On Tue, 16 Jan 2007 07:39:03 +0000, Eeyore
wrote:


In any event, an audible difference between DC and AC heating of DHTs indicates
to me that with AC there must be some signal modulation at 2 x line frequency,
like a tiny tremolo effect perhaps.

On the contrary, thermal time constant is too large for
heating to modulate emissivity even locally, and AC
heating is always used with hum nulling, which coincidentally
*exactly* (think carefully before disagreeing publicly)
also nulls all localized signal modulations.

If you and Arny really want to play in our sandbox,
at least do your homework first.

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

[Iain Churches]

"Arny Krueger" wrote in message
. ..
"Peter Wieck" wrote in message
ups.com

How long it remains true is a different question, as
trends evolve.

That it is true at all, remains questionable.

Arny. You remind one of the agnostic, dyslectic,
insomniac who lays awake at night wondering
"Is there a Dog?"

:-)
Iain

[Patrick Turner]

Iain Churches wrote:

"Arny Krueger" wrote in message
. ..
"Peter Wieck" wrote in message
ups.com

How long it remains true is a different question, as
trends evolve.

That it is true at all, remains questionable.

Arny. You remind one of the agnostic, dyslectic,
insomniac who lays awake at night wondering
"Is there a Dog?"

:-)
Iain

And "Is it biting my arse or is it not?"

Patrick Turner.

[Arny Krueger]

"Chris Hornbeck" wrote in
message
On Tue, 16 Jan 2007 07:39:03 +0000, Eeyore
wrote:

In any event, an audible difference between DC and AC
heating of DHTs indicates to me that with AC there must
be some signal modulation at 2 x line frequency, like a
tiny tremolo effect perhaps.

Given what we can do with modern measurement techniques, I'm sure we can
measure some.

On the contrary, thermal time constant is too large for
heating to modulate emissivity even locally,

First Chris says that there are no local signal modulations

and AC
heating is always used with hum nulling, which
coincidentally *exactly* (think carefully before
disagreeing publicly)
also nulls all localized signal modulations.

Then Chris says that there are local signal modulations, but they get nulled
out.

If the amplifier is nonlinear enough, nulling out zero-signal hum is not
going to nail the modulation effects with far larger signals. Since we are
probably talking designs with minimal loop feedback, they are probably
nonlinear enough.

If you and Arny really want to play in our sandbox,
at least do your homework first.

Frankly, I had way too much practical experience with all of the above, back
in the day.

I owned an Eico ST-70 which had AC-operated filaments in both the preamp and
amp stages. I could never get the hum down to what I considered to be
acceptable levels. In fact if I got things nicely nulled for one channel,
that de-optimized the other channel.

I subsequently owned a PAS3 and currently own a CJ that is pretty much a
PAS3 with some relevant circa-1980s technology added in. They both have
DC-operated filaments and they are both *really* free of hum.

[Arny Krueger]

"Iain Churches" wrote in message
i
"Arny Krueger" wrote in message
. ..
"Peter Wieck" wrote in message
ups.com

How long it remains true is a different question, as
trends evolve.

That it is true at all, remains questionable.

Arny. You remind one of the agnostic, dyslectic,
insomniac who lays awake at night wondering
"Is there a Dog?"

Speaks to the shallow cogitation that you've substituted for deep thought
for your entire life, Iain.

[John Byrns]

In article ,
"Arny Krueger" wrote:

Frankly, I had way too much practical experience with all of the above, back
in the day.

I owned an Eico ST-70 which had AC-operated filaments in both the preamp and
amp stages.

Since when did the Eico ST-70 use any filamentary tubes?

I could never get the hum down to what I considered to be
acceptable levels. In fact if I got things nicely nulled for one channel,
that de-optimized the other channel.

Sounds like the ST-70 only had one hum balance control for both channels
rather than a separate control for each channel?

I subsequently owned a PAS3 and currently own a CJ that is pretty much a
PAS3 with some relevant circa-1980s technology added in. They both have
DC-operated filaments and they are both *really* free of hum.

Hum free AC heated preamps can be done but it takes a lot of hard work,
the engineers that designed the PAS3 and CJ, or their bean counter
handlers, just didn't want to spend the time necessary to do the job
right and took the easy way out using DC.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Arny Krueger]

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

Frankly, I had way too much practical experience with
all of the above, back in the day.

I owned an Eico ST-70 which had AC-operated filaments in
both the preamp and amp stages.

Since when did the Eico ST-70 use any filamentary tubes?

AFAIK all the tubes were indirectly heated cathodes, but there are still
filaments inside the cathode tubes.

I could never get the hum down to what I considered to be
acceptable levels. In fact if I got things nicely nulled
for one channel, that de-optimized the other channel.

Sounds like the ST-70 only had one hum balance control
for both channels rather than a separate control for each
channel?

Correct. Also, only one 6.3 volt winding on the power transformer.

I subsequently owned a PAS3 and currently own a CJ that
is pretty much a PAS3 with some relevant circa-1980s
technology added in. They both have DC-operated
filaments and they are both *really* free of hum.

Hum free AC heated preamps can be done but it takes a lot
of hard work, the engineers that designed the PAS3 and
CJ, or their bean counter handlers, just didn't want to
spend the time necessary to do the job right and took the
easy way out using DC.

I think you've got it all turned around. Especially with a high volume item
like the PAS-3, it would have been well-worth the engineering time to obtain
the cost savings in parts. They would have saved big bucks by avoiding the
DC power supply for the filaments, especially in those days before $0.05
silicon diodes. It just wasn't the best way, partially because the AC
filament lines would have still radiated hum wherever they went.

BTW when I was in the military I worked on some very expensive, well-made,
large and complex tubed equipment. We're talking like 400 tubes per unit. DC
filament power was the rule. I believe there is also a tube life advantage
with DC filament power. win-win-win!

[Iain Churches]

"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message

"Arny Krueger" wrote in message
. ..

More to the point, most audiophiles long ago observed
that tubed amps aren't worth the trouble or expense.

Arny. I don't know about the situation in the US but here
in Scandinavia your statement could not be more wrong:-(

A recent survey here has shown that the top of the
high-end market for music systems (not home theatre)
is totally dominated by tube amplifiers.


When you have some audited stats from an independent source, be sure to
post them Iain. Until then, it looks like you're talking out of the back
of your neck, as usual. ;-(

This is a trend which has been on an upward slope for about
two years or so. You will find the article, and the data on which
it is based in Dagens Bladet Nyheter.

Can you read Swedish, Arny? (probably not - I notice you
often struggle in your native English)


Cordially,
Iain

[Arny Krueger]

"Iain Churches" wrote in message
i
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message

"Arny Krueger" wrote in message
. ..

More to the point, most audiophiles long ago observed
that tubed amps aren't worth the trouble or expense.

Arny. I don't know about the situation in the US but
here in Scandinavia your statement could not be more
wrong:-( A recent survey here has shown that the top of the
high-end market for music systems (not home theatre)
is totally dominated by tube amplifiers.


When you have some audited stats from an independent
source, be sure to post them Iain. Until then, it looks
like you're talking out of the back of your neck, as
usual. ;-(

This is a trend which has been on an upward slope for
about two years or so. You will find the article, and the data
on which it is based in Dagens Bladet Nyheter.

Oh, its a trend, not an accomplished fact like you first suggested. IOW,
your claim is speculative. Figures.

Can you read Swedish, Arny? (probably not - I notice you
often struggle in your native English)

Silly me, I thought that there was more to Scandanavia than just Sweden.

[Chris Hornbeck]

On Wed, 17 Jan 2007 10:00:17 -0500, "Arny Krueger"
wrote:

On the contrary, thermal time constant is too large for
heating to modulate emissivity even locally,

First Chris says that there are no local signal modulations

and AC
heating is always used with hum nulling, which
coincidentally *exactly* (think carefully before
disagreeing publicly)
also nulls all localized signal modulations.

Then Chris says that there are local signal modulations, but they get nulled
out.

I obviously need to spell it out in detail. A DC gradient
across the filament in a directly heated valve is a DC gradient
across the grid-"cathode" voltage. This effects the exponent in
Child's approximation. Changes in this exponent for a linear valve
inherently cause non-linearity to increase. It's easily measurable.


If you and Arny really want to play in our sandbox,
at least do your homework first.

Frankly, I had way too much practical experience with all of the above, back
in the day.

Frankly, we in rec.audio.tubes would appreciate the benefit
of your experience. And frankly, what we receive instead is
sniping, attack and proselytizing. You and Graham (who at
least took the trouble to understand this issue) have
valuable experience and insight that would benefit the newsgroup
greatly, ...if offered.

So I appeal to you both. We in rec.audio.tubes are not fools. We
like our grass skirts and our topless women just fine as is,
thank you. We don't need *your* religion, however much of it we
each personally incorporate. We have our own goals and interests,
and outlanders spreading Their Gospel, and nothing else, don't
contribute; they hinder.

If our goals and interests don't interest you enough to contribute
positively, please don't waste time here.

If, OTOH, you'd consider contributing positively here (as you do
in so many other newsgroup areas), we'd all be the better for it.

Much thanks, as always,

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

[John Byrns]

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

Frankly, I had way too much practical experience with
all of the above, back in the day.

I owned an Eico ST-70 which had AC-operated filaments in
both the preamp and amp stages.

Since when did the Eico ST-70 use any filamentary tubes?

AFAIK all the tubes were indirectly heated cathodes, but there are still
filaments inside the cathode tubes.

I think they call those heaters, not filaments.

I could never get the hum down to what I considered to be
acceptable levels. In fact if I got things nicely nulled
for one channel, that de-optimized the other channel.

Sounds like the ST-70 only had one hum balance control
for both channels rather than a separate control for each
channel?

Correct. Also, only one 6.3 volt winding on the power transformer.

That goes without saying, two hum balance controls on one winding
wouldn't work and could make for some interesting fireworks.

I subsequently owned a PAS3 and currently own a CJ that
is pretty much a PAS3 with some relevant circa-1980s
technology added in. They both have DC-operated
filaments and they are both *really* free of hum.

Hum free AC heated preamps can be done but it takes a lot
of hard work, the engineers that designed the PAS3 and
CJ, or their bean counter handlers, just didn't want to
spend the time necessary to do the job right and took the
easy way out using DC.

I think you've got it all turned around. Especially with a high volume item
like the PAS-3, it would have been well-worth the engineering time to obtain
the cost savings in parts. They would have saved big bucks by avoiding the
DC power supply for the filaments, especially in those days before $0.05
silicon diodes. It just wasn't the best way, partially because the AC
filament lines would have still radiated hum wherever they went.

There are also cost items associated with AC heating. The engineering
cost per unit would depend on the size of the model run. That assumes
the manufacturer could even find an engineer that would take on this
sort of thankless work, and also knew how to accomplish it. I suspect
the PAS3 also used Printed Circuit Boards, which probably wouldn't be
compatible AC heating, especially the sort used in the days of the PAS3.
That would force hand wiring of the chassis which would drive up the
costs of AC heating. Also the type of wiring layout required for AC
heating may not be compatible with desired packaging format. 12AX7s are
also not good for AC heating, suitable tubes may be more expensive.
Finally there is the cost of the hum balance controls and their
adjustment on the production line. There are probably other costs of AC
heating that I have forgotten about.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Iain Churches]

"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
i
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message

"Arny Krueger" wrote in message
. ..

More to the point, most audiophiles long ago observed
that tubed amps aren't worth the trouble or expense.

Arny. I don't know about the situation in the US but
here in Scandinavia your statement could not be more
wrong:-( A recent survey here has shown that the top of the
high-end market for music systems (not home theatre)
is totally dominated by tube amplifiers.


When you have some audited stats from an independent
source, be sure to post them Iain. Until then, it looks
like you're talking out of the back of your neck, as
usual. ;-(

This is a trend which has been on an upward slope for
about two years or so. You will find the article, and the data
on which it is based in Dagens Bladet Nyheter.

Oh, its a trend, not an accomplished fact like you first suggested. IOW,
your claim is speculative. Figures.

Can you read Swedish, Arny? (probably not - I notice you
often struggle in your native English)

Silly me, I thought that there was more to Scandanavia than just Sweden.

Silly you are indeed, Arny.The survey related to the Scandinavian
countries, and is plublished (in Swedish) in a Swedish publication.
Do you now understand?

Iain

[Arny Krueger]

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article
, "Arny
Krueger" wrote:

Frankly, I had way too much practical experience with
all of the above, back in the day.

I owned an Eico ST-70 which had AC-operated filaments
in both the preamp and amp stages.

Since when did the Eico ST-70 use any filamentary tubes?

AFAIK all the tubes were indirectly heated cathodes, but
there are still filaments inside the cathode tubes.

I think they call those heaters, not filaments.

There's no general standard.

I could never get the hum down to what I considered to
be acceptable levels. In fact if I got things nicely
nulled for one channel, that de-optimized the other
channel.

Sounds like the ST-70 only had one hum balance control
for both channels rather than a separate control for
each channel?

Correct. Also, only one 6.3 volt winding on the power
transformer.

That goes without saying, two hum balance controls on one
winding wouldn't work and could make for some interesting
fireworks.

2 hum balance controls wouldn't be any more effective, but I don't think
there would necessarily be fireworks. There would just be a common
adjustment with two interacting controls.

I subsequently owned a PAS3 and currently own a CJ that
is pretty much a PAS3 with some relevant circa-1980s
technology added in. They both have DC-operated
filaments and they are both *really* free of hum.

Hum free AC heated preamps can be done but it takes a
lot of hard work, the engineers that designed the PAS3
and CJ, or their bean counter handlers, just didn't
want to spend the time necessary to do the job right
and took the easy way out using DC.

I think you've got it all turned around. Especially with
a high volume item like the PAS-3, it would have been
well-worth the engineering time to obtain the cost
savings in parts. They would have saved big bucks by
avoiding the DC power supply for the filaments,
especially in those days before $0.05 silicon diodes. It
just wasn't the best way, partially because the AC
filament lines would have still radiated hum wherever
they went.

There are also cost items associated with AC heating.
The engineering cost per unit would depend on the size of
the model run. That assumes the manufacturer could even
find an engineer that would take on this sort of
thankless work, and also knew how to accomplish it. I
suspect the PAS3 also used Printed Circuit Boards, which
probably wouldn't be compatible AC heating, especially
the sort used in the days of the PAS3.

The Dyna tubed gear also used twisted pair wiring with their circuit cards.

That would force
hand wiring of the chassis which would drive up the costs
of AC heating.

The Dyna tubed gear used a mixture of PC cards and hand wiring.

Also the type of wiring layout required
for AC heating may not be compatible with desired
packaging format. 12AX7s are also not good for AC
heating, suitable tubes may be more expensive.

Speculation is not proof, or even good evidence.

Finally
there is the cost of the hum balance controls and their
adjustment on the production line. There are probably
other costs of AC heating that I have forgotten about.

In the days of tubes, AC power to the heaters was common on cheap gear, and
was itself a cost-saving move. Selenium rectifiers were big, expensive and
inefficient.

[Arny Krueger]

"Chris Hornbeck" wrote in
message
On Wed, 17 Jan 2007 10:00:17 -0500, "Arny Krueger"
wrote:

On the contrary, thermal time constant is too large for
heating to modulate emissivity even locally,

First Chris says that there are no local signal
modulations

and AC
heating is always used with hum nulling, which
coincidentally *exactly* (think carefully before
disagreeing publicly)
also nulls all localized signal modulations.

Then Chris says that there are local signal modulations,
but they get nulled out.

I obviously need to spell it out in detail. A DC gradient
across the filament in a directly heated valve is a DC
gradient across the grid-"cathode" voltage. This effects
the exponent in Child's approximation. Changes in this
exponent for a linear valve inherently cause
non-linearity to increase. It's easily measurable.

You're not addressing your self-contrdiction, just restating half of it.

If you and Arny really want to play in our sandbox,
at least do your homework first.

Frankly, I had way too much practical experience with
all of the above, back in the day.

Frankly, we in rec.audio.tubes would appreciate the
benefit of your experience.

You got it and then you started sniping at it.

And frankly, what we receive instead is
sniping, attack and proselytizing.

Nice job of not taking responsibility for your own actions, Chris. Nice job
of making a technical discussion into a series of personal attacks.

You and Graham (who at
least took the trouble to understand this issue) have
valuable experience and insight that would benefit the
newsgroup greatly, ...if offered.

You got it and then you started sniping at it.

So I appeal to you both. We in rec.audio.tubes are not
fools. We like our grass skirts and our topless women
just fine as is, thank you. We don't need *your* religion, however much
of
it we each personally incorporate. We have our own goals and
interests, and outlanders spreading Their Gospel, and
nothing else, don't contribute; they hinder.

There's no religion in our posts, just the relevant facts and maybe a few
vain attempts to defend ourselves from gratuitous personal attacks.

[Arny Krueger]

"Iain Churches" wrote in message
i
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
i
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in
message

"Arny Krueger" wrote in message
. ..

More to the point, most audiophiles long ago observed
that tubed amps aren't worth the trouble or expense.

Arny. I don't know about the situation in the US but
here in Scandinavia your statement could not be more
wrong:-( A recent survey here has shown that the top
of the high-end market for music systems (not home
theatre) is totally dominated by tube amplifiers.


When you have some audited stats from an independent
source, be sure to post them Iain. Until then, it looks
like you're talking out of the back of your neck, as
usual. ;-(

This is a trend which has been on an upward slope for
about two years or so. You will find the article, and
the data on which it is based in Dagens Bladet Nyheter.

Oh, its a trend, not an accomplished fact like you first
suggested. IOW, your claim is speculative. Figures.

Can you read Swedish, Arny? (probably not - I notice
you often struggle in your native English)

Silly me, I thought that there was more to Scandanavia
than just Sweden.

Silly you are indeed, Arny.The survey related to the
Scandinavian countries, and is plublished (in Swedish) in
a Swedish publication. Do you now understand?

I see no relevant evidence, just vague citations.

[Iain Churches]

"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
i
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
i
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in
message

"Arny Krueger" wrote in message
. ..

More to the point, most audiophiles long ago observed
that tubed amps aren't worth the trouble or expense.

Arny. I don't know about the situation in the US but
here in Scandinavia your statement could not be more
wrong:-( A recent survey here has shown that the top
of the high-end market for music systems (not home
theatre) is totally dominated by tube amplifiers.


When you have some audited stats from an independent
source, be sure to post them Iain. Until then, it looks
like you're talking out of the back of your neck, as
usual. ;-(

This is a trend which has been on an upward slope for
about two years or so. You will find the article, and
the data on which it is based in Dagens Bladet Nyheter.

Oh, its a trend, not an accomplished fact like you first
suggested. IOW, your claim is speculative. Figures.

Can you read Swedish, Arny? (probably not - I notice
you often struggle in your native English)

Silly me, I thought that there was more to Scandanavia
than just Sweden.

Silly you are indeed, Arny.The survey related to the
Scandinavian countries, and is plublished (in Swedish) in
a Swedish publication. Do you now understand?

I see no relevant evidence, just vague citations.

Did you read the article, and look at the sales analysis
charts? It's all there.

Iain

[Arny Krueger]

"Iain Churches" wrote in message

"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in message
i
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in
message
i
"Arny Krueger" wrote in message
. ..
"Iain Churches" wrote in
message

"Arny Krueger" wrote in message
. ..

More to the point, most audiophiles long ago
observed that tubed amps aren't worth the trouble
or expense.

Arny. I don't know about the situation in the US but
here in Scandinavia your statement could not be more
wrong:-( A recent survey here has shown that the top
of the high-end market for music systems (not home
theatre) is totally dominated by tube amplifiers.


When you have some audited stats from an independent
source, be sure to post them Iain. Until then, it
looks like you're talking out of the back of your
neck, as usual. ;-(

This is a trend which has been on an upward slope for
about two years or so. You will find the article, and
the data on which it is based in Dagens Bladet
Nyheter.

Oh, its a trend, not an accomplished fact like you
first suggested. IOW, your claim is speculative.
Figures.
Can you read Swedish, Arny? (probably not - I notice
you often struggle in your native English)

Silly me, I thought that there was more to Scandanavia
than just Sweden.

Silly you are indeed, Arny.The survey related to the
Scandinavian countries, and is plublished (in Swedish)
in a Swedish publication. Do you now understand?

I see no relevant evidence, just vague citations.

Did you read the article, and look at the sales analysis
charts? It's all there.

It's quite clear Iain, that you don't have the foggiest notion what a proper
quotation looks like. I'm sorry to engage you, an unarmed man, in a battle
of wits.

[Iain Churches]

"Arny Krueger" wrote in message
news
"John Byrns" wrote in message

Since when did the Eico ST-70 use any filamentary tubes?

AFAIK all the tubes were indirectly heated cathodes, but
there are still filaments inside the cathode tubes.

I think they call those heaters, not filaments.

There's no general standard.

Take a look at RDH or Tremaine, Lewis Yorke
or any of the other training textbooks and manuals.

You will find that they specifically refer to filaments
for directly heated triodes, and heaters for indirectly
heated valves. So everyone understands (with the
possible exception of your good self, Arny-)
that a filamentary triode is a DHT.

Iain

[Andre Jute]

The friends of Don Pearce may want to skip this message. I held it over
for several days in the hope that one of the other siliconiteys would
straighten out one of their own so that I could appear magisterially
above the grubbing of "engineers" but clearly they aren't interested in
truth, only in "winning" something. This post demonstrates that Pearce
cannot read a schematic, doesn't know anything about tube amp design
(he mistakes a grid leak for a feedback resistor!), proceeds from
unscientific prejudice rather than the facts, and besides suffers from
a deficit in English comprehension and that minimum numeracy we have a
right to expect from an "engineer" who blusters out moral condemnations
about other people's component counts. As I say, the friends of Don
Pearce read on at their own risk: I am not responsible for foaming at
the mouth, apoplectic fits, and other symptoms of siliconitis.

Even if you don't read all of this post, enjoy this bit of bluster from
that clown Pearce before I whack him like the empty cheap-plastic pouch
of stale air that he is (a table tennis ball comes to mind):
don't try your nonsense
with me. You may get away with it with your dullard mates, so stick
with them.

Now let's see who is a dumbo:


Don Pearce wrote:
"Andre Jute" wrote:

Thanks for the effort, Pearce. I wasn't seriously putting forward the
Gaincard method of counting, just throwing it in for discussion while I
get on with the business of designing and building my next amp.

However, the grid leak resistor which you call the "47k feedback r"
raises an interesting point of difference between the silicon crowd and
the zero negative feedback ultrafidelista faithful. You intend to mean
by negative feedback *any* feedback. By convention tubies in general
and ultrafidelista in particular by negative feedback mean global or
universal or loop negative feedback, certainly nothing contained within
one stage of any of the classical topologies (including those newly
revived like the mu stage). Even a cathode follower, surely a feedback
device!, is kosher to the ZNFB crowd, and they have often resented me
for pointing it out as much as the silicon slime has resented me for
pointing out *their* wishful thinking and other depredations on the
immutable laws of physics. (Hey, there are some tubies who still want
to lynch me ten years later for puncturing their bubble on SRPP, which
until I made an irrefutable analysis they happily promoted for thirty
years as a constant current-loaded triode, which of course it isn't.)


My error on the 47k - apologies tendered.

Now an idiot who mistakes a grid leak resistor (the most common
component on tube circuits next to tubes themselves!) goes on to
lecture me about topologies:

But then you beg the question (and I mean that in the true sense of
the logical fallacy), when you start to claim that feedback isn't
feedback because you define it thus. Well, I have news for you.
Feedback IS feedback, however you apply it. If the output signal is
capable of comparison with the input and thereby reducing some of its
error, you have feedback - live with it and don't try your nonsense
with me. You may get away with it with your dullard mates, so stick
with them.

You have an English comprehension problem, Pearce. Let me give it to
you by numbers in simple soundbites.
1. I didn't beg any question.
2. I described a view held by others.
3. I said plainly that I pointed out to them that they are wrong.
4. The implication, plain as the nose on your smug mug, is that I think
they are wrong.
5. Now you accuse me of sharing their view.
6. And you add some dumb moralizing crap: "don't try your nonsense
with me. You may get away with it with your dullard mates, so stick
with them."

Are you surprised, then, Pearce, that I publicly call you a moron and
treat you with contempt? You're thick, you're illiterate, you bluster,
you're a bully, and you aren't even amusing.

You counted the "47k feedback r" (the grid leak, without which the amp
won't work) twice.

And you're either innumerate as well or you cheat. Then you proceed
with totally unscientific prejudice:

Of course the whole thing makes a bit of sense when you
consider that the components in this amp are doing a
disproportionately huge amount of damage to the signal. Which they
are. Ultrafi is an interestingly ironic name, don't you think?

It is rather interesting that you don't ask for the noise figures of my
tube amp before you start spouting condemnations based on your
prejudicial preference for silicon bodged nearly right with excessive
negative feedback.

Why would I give a toss about the noise figure of a power amp? It
didn't even occur to me that you might screw that up.

Then how can you claim, as you do above, that "the components in this
amp are doing a
disproportionately huge amount of damage to the signal". You have no
evidence, you haven't asked for evidence, you have in public in writing
refused to look at evidence to the contrary. That defines an
unscientific prejudice.

In fact, it is clearly analogous to fearful prejudice of the most
fanatical religious type, an atavistic cringing at the danger of being
tempted by the devil of musical pleasure. If hi-fi is merely a scourge
for your own unworthiness, Pearcey, enjoy whipping yourself. But don't
spray the spittle of your obscene betrayal of scientic principle on me,
if you don't mind.

Have you?

Screwed it up? Nah. It is impossible to screw up a 300B amp. You should
try it. Even you could probably build one that's nearly good. If you
can't read my circuit, just ask on RAT and I or Patrick or John or
Chris or Al or Raymond or Bob or any one of many others will explain it
to you.

Perhaps you should at least draw the loadline on the tube transfer
curves and calculate the distortion before you spout off, Pearce. If
you know how, of course. You might surprise yourself. (I hesitate to
suggest that you build the design and measure for yourself; I wouldn't
want you to electrocute yourself on unaccustomed high voltage or burn
yourself with your new soldering iron.)

Sorry, miscounted.

Again. Did I say innumerate yet?

I hadn't spotted the two 100 ohm resistors and 100
ohm pot forming the series feedback network on the output valve were
carrying signal. Hang - this amp is not meant to have any feedback -
what are they doing there?

They're humbusters for the AC filaments. You do know that DC filaments
on DHT sound like ****, don't you, Pearce? Now go on, tell me about the
joys of regulation.

So you are claiming that an unbypassed cathode resistor is NOT a
voltage feedback system?

I didn't say that, Pearce. Once more you're trying to put words into my
mouth that I didn't speak in your clumsy attempts to make me fit some
crude stereotype of tubies you have in your railroad mind.

Your technical abilities plumb yet greater
depths.

And once more, Pearce, on no evidence whatsoever, except your dumb
prejudice, you come to a dumb, sweeping conclusion. You haven't made a
single good point about the schematic I published, Pearce. You didn't
even spot an earth bumped into the wrong place when I redrew the schemo
to add snubbers across the chokes. That is something I would expect a
first year engineering student to pick up. You didn't.

Pearce Consulting
http://www.pearce.uk.com

What do you consult on, Pearce? Prejudice? It can't be logic, because
you have none, it can't be science because you proceed by prejudice
rather than evidence, it can't be electronics because you can't even
spot a ground in the wrong place, and it sure as hell can't be audio
engineering because you mistake a grid leak for a feedback resistor.

Always great to hear from you, Pearce. It gives me a warm glow of
superiority that a famous engineer like you, a proven hostile to tube
amps, can find only twee tiny quibbles when I publish a design.

When you publish a design claiming it to have no feedback, and I can
show that it does indeed use feedback, you can expect me to speak.
Bull**** always stinks.

So it does. And, as I have demonstrated conclusively from your own
words, you're the one who stinks to high heaven of unscientific
prejudice, the worst kind of bull****.

Now let's read Pearce's amazing summary of his triumph of "logic",
which he must learned from that malicious clown Krueger:
When you claim there are only six components in the signal path and I
count 17 (yes, still apologies for the miscount and misidentification
- apropos of which you might want to redraw the schematic to make that
57k look a bit less like a feedback resistor), you can expect me to
speak. Even you should be able to count a bit better than that.

That short paragraph by Pearce contains the following lies:
1. I didn't "claim there are only six components:. I made fun of the
Gaincard folk by ridiculing their method of counting, mainly as a
distraction for fools like Pearce while those of us more capable got on
with inspecting the schematic. I am not responsible if people like
Pearce, in dire need of a humour transplant, possess zero grasp of the
subtleties of the English language. Railroad minds needn't apply.

2. I didn't misplace or otherwise misrepresent the grid leak resistor.
It has been drawn in that position in that manner since the First World
War. Pearce is just bog ignorant and is now making excuses for his
ignorance on a matter he tries to pontificate on. Still, his ignorant
bluster tells us a lot about the real Don Pearce.

****

In summary, throwing a couple of red rags into the arena for the dumber
bulls to worry while the rest of us got on with the real work was not
merely successful in its own terms but offered amusement for a bonus.
It was also most educational in exposing about Pearce:

1. Pearce's dire ignorance. He cannot distinguish a grid leak from a
feedback resistor. He apparently doesn't know where an earth should be
placed in a power supply.

2. Pearce's unscientific behaviour. He calls a signal damaged. He is
offered evidence to the contrary. He refuses to look at it. He repeats
his prejudiced statement.

3. The lacunae in Pearce's education. He cannot comprehend
straightforward English through the fog of his prejudice. He has no
sense of humour: he cannot see a tongue mountainously bulged into a
cheek. He cannot count. He doesn't understand that science progresses
by evidence rather than prejudice. He cannot even read a basic
schematic.

Makes you wonder, eh?

Andre Jute
The trouble with Don Pearce is not what he doesn't know, but what he
knows for certain that isn't true. --- with apologies to Mark Twain

[Peter Wieck]

Andrew Jute McCoy blathered:

A bunch of disjointed tripe.

Just cut to the chase, poseur... show us the completed amp. Working.
Witnessed by an independent and verifiable source. With a copy of a
recent newspaper headline in the frame.

You cannot. And will never. So no amount of smoke and mirrors, blather
and ranting will gain you anything but the credibility you deserve.

Peter Wieck
Wyncote, PA

[Andre Jute]

Chris Hornbeck wrote:
On 14 Jan 2007 16:01:40 -0800, "Andre Jute" wrote:

Grounding is one of the last, possibly the last, unexplored
frontiers in hi-fidelity tube amplifiers.

Hopefully not the last, but certainly one of the most
important, and definitely *the most* ignored for
typical homebrew (and, sadly, too many commercial)
designs.

Much thanks, as always,

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

On the evidence in this thread, I'd say filament supplies make another
unfinished subject, right up there with grounding. -- Andre Jute

[Andre Jute]

Chris Hornbeck wrote:

On Tue, 16 Jan 2007 07:39:03 +0000, Eeyore
wrote:

In any event, an audible difference between DC and AC heating of DHTs indicates
to me that with AC there must be some signal modulation at 2 x line frequency,
like a tiny tremolo effect perhaps.

On the contrary, thermal time constant is too large for
heating to modulate emissivity even locally, and AC
heating is always used with hum nulling, which coincidentally
*exactly* (think carefully before disagreeing publicly)
also nulls all localized signal modulations.

The relevant circuits are at:
http://members.lycos.co.uk/fiultra/T...trafi-crct.jpg
http://members.lycos.co.uk/fiultra/T44bis-'Populaire'-crct.jpg

The hum nulling, for visiting siliconheads who clearly don't know
anything about tube circuits, consists of the circuit in the Western
Electric 300B cathode (that's the lower part of the tube, chaps) made
up of two 100 ohm resistors and the 100 ohm pot. (This has, amazingly,
already been described by Don Pearce in this thread as if it is merely
a feedback mechanism. Nor did Pearce enquire after its purpose...
Perhaps Pearce has negative feedback on the brain, because he also
twice described the grid leak resistor as a negative feedback network;
interestingly, none of the other siliconitis sufferers afflicting us
know enough about tube circuits to correct this gross error by
Pearce.)

The designs are discussed in these texts:
http://members.lycos.co.uk/fiultra/T...mp%20INDEX.htm

If you and Arny really want to play in our sandbox,
at least do your homework first.

They don't want to play in our sandbox. They want to **** in it, to
suck the jam from our doughnut, to drain the glee from our hobby. It
offends these grim witchfinders that we are having fun.

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

[John Byrns]

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article
, "Arny
Krueger" wrote:

Frankly, I had way too much practical experience with
all of the above, back in the day.

I owned an Eico ST-70 which had AC-operated filaments
in both the preamp and amp stages.

Since when did the Eico ST-70 use any filamentary tubes?

AFAIK all the tubes were indirectly heated cathodes, but
there are still filaments inside the cathode tubes.

I think they call those heaters, not filaments.

There's no general standard.

Sure there is, you just choose not to accept it.

In the days of tubes, AC power to the heaters was common on cheap gear, and
was itself a cost-saving move. Selenium rectifiers were big, expensive and
inefficient.

And a lot of very expensive equipment also used AC heating. For
instance a well known manufacturer of ribbon microphones used AC heating
in their immediate post WW2 line of microphone preamps, they could have
used selenium rectifiers for DC heating as others did at the time.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Andre Jute]

Andre Jute wrote:
Chris Hornbeck wrote:

On Tue, 16 Jan 2007 07:39:03 +0000, Eeyore
wrote:

In any event, an audible difference between DC and AC heating of DHTs indicates
to me that with AC there must be some signal modulation at 2 x line frequency,
like a tiny tremolo effect perhaps.

On the contrary, thermal time constant is too large for
heating to modulate emissivity even locally, and AC
heating is always used with hum nulling, which coincidentally
*exactly* (think carefully before disagreeing publicly)
also nulls all localized signal modulations.

The relevant circuits are at:
http://members.lycos.co.uk/fiultra/T...trafi-crct.jpg
http://members.lycos.co.uk/fiultra/T44bis-'Populaire'-crct.jpg

The hum nulling, for visiting siliconheads who clearly don't know
anything about tube circuits, consists of the circuit in the Western
Electric 300B cathode (that's the lower part of the tube, chaps) made
up of two 100 ohm resistors and the 100 ohm pot. (This has, amazingly,
already been described by Don Pearce in this thread as if it is merely
a feedback mechanism. Nor did Pearce enquire after its purpose...
Perhaps Pearce has negative feedback on the brain, because he also
twice described the grid leak resistor as a negative feedback network;
interestingly, none of the other siliconitis sufferers afflicting us
know enough about tube circuits to correct this gross error by
Pearce.)

The designs are discussed in these texts:
http://members.lycos.co.uk/fiultra/T...mp%20INDEX.htm

If you and Arny really want to play in our sandbox,
at least do your homework first.

They don't want to play in our sandbox. They want to **** in it, to
suck the jam from our doughnut, to drain the glee from our hobby. It
offends these grim witchfinders that we are having fun.

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

A copy to UKRA so Pearce can't say I knock him behind his back. -- AJ

[Chris Hornbeck]

On 18 Jan 2007 18:16:15 -0800, "Andre Jute" wrote:

On the evidence in this thread, I'd say filament supplies make another
unfinished subject, right up there with grounding.

It's certainly a difficult subject for a newsgroup discussion.
Maybe it's the restriction to a plain text format, and maybe
(much more likely, actually) it's my poor ability to convey
(without a lot of handwaving or even a coupla graphs) arcana
about an unfamiliar topic, but I've had very mixed results
(an _Annie Hall_ reference; only funny if you loved
the movie) discussing the difference between AC and DC
filament supplies with two very bright guys on this very
thread.

Not enough points of reference; the bane of newsgroup
discussions everywhere, to say nothing of intergenderbanter.

It's a stone beotch but the valves big enough and linear
enough to be interesting to many of us hifi snobs are filamentary
triodes. The lack of a separate cathode is a huge pain in the
patootie, so work-arounds are a very important discussion.
Fortunately, all the real work was done before we were born;
just a matter of getting the word out.

Much thanks, as always,

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

[Chris Hornbeck]

On Thu, 18 Jan 2007 08:26:41 -0500, "Arny Krueger"
wrote:

You're not addressing your self-contradiction, just restating half of it.

I can't see it, but maybe that's the nature of self-(anything).
Maybe I should start over:

The topic here is "filamentary triodes", antique devices
chosen for their transfer linearity, because they have *no*
other virtues. Cathode electron emission can only happen
with direct voltage-across-the-cathode-its-ownself heating.

An AC heating voltage across the filament/cathode must be
nulled in the signal path to eliminate hum, but the null
by definition averages the whole emissive surface from a
signal POV. This is an important and non-intuitive point,
and worth study.

To put it another way, signal is independent of variations
in localized instantaneous cathode-grid voltage and the
proof is the lack of hum.

A DC heating voltage across the filament/cathode has no hum
issue, but has a different subtler effect. Opposite ends of
the filament/cathode have different voltages WRT the grid, so
have different "plate curves". In an ideal infinitely large
surface these differences would average to same-same, but
in real world dimensions, they increase the Child exponent.

Graham nailed it by comparing the effect to a variable-mu
valve. In valves of interest the actual effect is much, much
smaller than that, but his analogy is perfect.

Some practical numbers: type 300 valves are often operated
with 80 volts grid-to-cathode and 5 volts for heating; type
211 may have 60 volts g-c and 10 volts heating; type 845
some 160 volts g-c and 10 volts heating.

Thanks for your interest and your input,

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

[Arny Krueger]

"Iain Churches" wrote in message
i
"Arny Krueger" wrote in message
news
"John Byrns" wrote in message

Since when did the Eico ST-70 use any filamentary
tubes?

AFAIK all the tubes were indirectly heated cathodes,
but there are still filaments inside the cathode tubes.

I think they call those heaters, not filaments.

There's no general standard.

Take a look at RDH or Tremaine, Lewis Yorke
or any of the other training textbooks and manuals.

Been there done that, both in the day of, and recently.

You will find that they specifically refer to filaments
for directly heated triodes, and heaters for indirectly
heated valves.

A few exceptions don't prove a general rule.

So everyone understands (with the
possible exception of your good self, Arny-)
that a filamentary triode is a DHT.

Thanks for making it personal, Iain. I know when I've hurt you when you
start runnning around and posting insults on anything of mine that you can
find.

[Sander deWaal]

"Andre Jute" said:


Andre Jute wrote:
Chris Hornbeck wrote:

On Tue, 16 Jan 2007 07:39:03 +0000, Eeyore
wrote:


In any event, an audible difference between DC and AC heating of DHTs indicates
to me that with AC there must be some signal modulation at 2 x line frequency,
like a tiny tremolo effect perhaps.


On the contrary, thermal time constant is too large for
heating to modulate emissivity even locally, and AC
heating is always used with hum nulling, which coincidentally
*exactly* (think carefully before disagreeing publicly)
also nulls all localized signal modulations.


The relevant circuits are at:
http://members.lycos.co.uk/fiultra/T...trafi-crct.jpg
http://members.lycos.co.uk/fiultra/T44bis-'Populaire'-crct.jpg

The hum nulling, for visiting siliconheads who clearly don't know
anything about tube circuits, consists of the circuit in the Western
Electric 300B cathode (that's the lower part of the tube, chaps) made
up of two 100 ohm resistors and the 100 ohm pot. (This has, amazingly,
already been described by Don Pearce in this thread as if it is merely
a feedback mechanism. Nor did Pearce enquire after its purpose...
Perhaps Pearce has negative feedback on the brain, because he also
twice described the grid leak resistor as a negative feedback network;
interestingly, none of the other siliconitis sufferers afflicting us
know enough about tube circuits to correct this gross error by
Pearce.)

The designs are discussed in these texts:
http://members.lycos.co.uk/fiultra/T...mp%20INDEX.htm


If you and Arny really want to play in our sandbox,
at least do your homework first.

They don't want to play in our sandbox. They want to **** in it, to
suck the jam from our doughnut, to drain the glee from our hobby. It
offends these grim witchfinders that we are having fun.


A copy to UKRA so Pearce can't say I knock him behind his back. -- AJ


Gotta give credit where credit is due, Andre, even if it is only 1 dB.
The 100 ohm potmeter, shunted by both 100 ohms resistors, provide a
very tiny amount of local cathode feedback.

--

- Maggies are an addiction for life. -

[Don Pearce]

On Fri, 19 Jan 2007 18:54:07 +0100, Sander deWaal
wrote:

"Andre Jute" said:


Andre Jute wrote:
Chris Hornbeck wrote:

On Tue, 16 Jan 2007 07:39:03 +0000, Eeyore
wrote:


In any event, an audible difference between DC and AC heating of DHTs indicates
to me that with AC there must be some signal modulation at 2 x line frequency,
like a tiny tremolo effect perhaps.


On the contrary, thermal time constant is too large for
heating to modulate emissivity even locally, and AC
heating is always used with hum nulling, which coincidentally
*exactly* (think carefully before disagreeing publicly)
also nulls all localized signal modulations.


The relevant circuits are at:
http://members.lycos.co.uk/fiultra/T...trafi-crct.jpg
http://members.lycos.co.uk/fiultra/T44bis-'Populaire'-crct.jpg

The hum nulling, for visiting siliconheads who clearly don't know
anything about tube circuits, consists of the circuit in the Western
Electric 300B cathode (that's the lower part of the tube, chaps) made
up of two 100 ohm resistors and the 100 ohm pot. (This has, amazingly,
already been described by Don Pearce in this thread as if it is merely
a feedback mechanism. Nor did Pearce enquire after its purpose...
Perhaps Pearce has negative feedback on the brain, because he also
twice described the grid leak resistor as a negative feedback network;
interestingly, none of the other siliconitis sufferers afflicting us
know enough about tube circuits to correct this gross error by
Pearce.)

The designs are discussed in these texts:
http://members.lycos.co.uk/fiultra/T...mp%20INDEX.htm


If you and Arny really want to play in our sandbox,
at least do your homework first.

They don't want to play in our sandbox. They want to **** in it, to
suck the jam from our doughnut, to drain the glee from our hobby. It
offends these grim witchfinders that we are having fun.


A copy to UKRA so Pearce can't say I knock him behind his back. -- AJ


Gotta give credit where credit is due, Andre, even if it is only 1 dB.
The 100 ohm potmeter, shunted by both 100 ohms resistors, provide a
very tiny amount of local cathode feedback.

Don't worry Sander, Jute is back in my killfile with Allison. He only
got out temporarily because I changed to a new laptop.

d

--
Pearce Consulting
http://www.pearce.uk.com

[Arny Krueger]

"flipper" wrote in message

On Fri, 19 Jan 2007 12:45:20 -0500, "Arny Krueger"
wrote:

"Iain Churches" wrote in message
i
"Arny Krueger" wrote in message
news "John Byrns" wrote in message

Since when did the Eico ST-70 use any filamentary
tubes?

AFAIK all the tubes were indirectly heated cathodes,
but there are still filaments inside the cathode
tubes.

I think they call those heaters, not filaments.

There's no general standard.

Take a look at RDH or Tremaine, Lewis Yorke
or any of the other training textbooks and manuals.

Been there done that, both in the day of, and recently.

You will find that they specifically refer to filaments
for directly heated triodes, and heaters for indirectly
heated valves.

A few exceptions don't prove a general rule.

Oh puleese, RDH, textbooks, and training materials aren't
"exceptions."

I see no specific reference to any proper textbook or training material.

RDH and Tremaine are legacy publications, and represent only a tiny fraction
of audio publications that are extant.

Furthermore, I can find no references to "Lewis Yorke" in any standard list
of publications. I found a post alleging "Lewis Yorke" wrote "High Fidelity
Valve Amplifiers", but guess what - I can find no references to "High
Fidelity Valve Amplifiers" in any standard list of publications. Must be
some kind of off-the-wall pamphlet.

Bottom line, the purported standard only exists in the minds of a few
obscure people and in a minority opinion based on just a few outdated
publications.

[Arny Krueger]

"flipper" wrote in message

On Fri, 19 Jan 2007 21:47:26 -0500, "Arny Krueger"
wrote:

"flipper" wrote in message

On Fri, 19 Jan 2007 12:45:20 -0500, "Arny Krueger"
wrote:

"Iain Churches" wrote in
message
i
"Arny Krueger" wrote in message
news "John Byrns" wrote in message

Since when did the Eico ST-70 use any filamentary
tubes?

AFAIK all the tubes were indirectly heated
cathodes, but there are still filaments inside the
cathode tubes.

I think they call those heaters, not filaments.

There's no general standard.

Take a look at RDH or Tremaine, Lewis Yorke
or any of the other training textbooks and manuals.

Been there done that, both in the day of, and recently.

You will find that they specifically refer to
filaments for directly heated triodes, and heaters
for indirectly heated valves.

A few exceptions don't prove a general rule.

Oh puleese, RDH, textbooks, and training materials
aren't "exceptions."

I see no specific reference to any proper textbook or
training material.

RDH and Tremaine are legacy publications, and represent
only a tiny fraction of audio publications that are
extant.

So, in your analysis, one of the premier designers and
builders of tubes of the time, and a revered reference,
doesn't know what they're talking about and is an
'exception'. Uh huh.

You've confused practical books with dictionaries.

Furthermore, I can find no references to "Lewis Yorke"
in any standard list of publications. I found a post
alleging "Lewis Yorke" wrote "High Fidelity Valve
Amplifiers", but guess what - I can find no references
to "High Fidelity Valve Amplifiers" in any standard
list of publications. Must be some kind of off-the-wall
pamphlet.

By all means, post your 'mainstream', not an 'exception',
reference material.

Not my job.

Bottom line, the purported standard only exists in the
minds of a few obscure people and in a minority opinion
based on just a few outdated publications.

I can't say there isn't a spec sheet somewhere that lists
it differently but in the few thousand I've collected
it's uniform. E.g. A 417A has a "heater" on pins 3 and 9
while a 2A3 has a "filament" on pins 1 and 4. Guess which
one is a DHT.

Good for you. Too bad that you have so little to do that you feel compelled
to waste your time with trivial issues like this.

[Andre Jute]

Sander deWaal wrote:
"Andre Jute" said:


Andre Jute wrote:
Chris Hornbeck wrote:

On Tue, 16 Jan 2007 07:39:03 +0000, Eeyore
wrote:


In any event, an audible difference between DC and AC heating of DHTs indicates
to me that with AC there must be some signal modulation at 2 x line frequency,
like a tiny tremolo effect perhaps.


On the contrary, thermal time constant is too large for
heating to modulate emissivity even locally, and AC
heating is always used with hum nulling, which coincidentally
*exactly* (think carefully before disagreeing publicly)
also nulls all localized signal modulations.


The relevant circuits are at:
http://members.lycos.co.uk.cob-web.o...trafi-crct.jpg
http://members.lycos.co.uk.cob-web.org:8888/fiultra/T44bis-'Populaire'-crct.jpg

The hum nulling, for visiting siliconheads who clearly don't know
anything about tube circuits, consists of the circuit in the Western
Electric 300B cathode (that's the lower part of the tube, chaps) made
up of two 100 ohm resistors and the 100 ohm pot. (This has, amazingly,
already been described by Don Pearce in this thread as if it is merely
a feedback mechanism. Nor did Pearce enquire after its purpose...
Perhaps Pearce has negative feedback on the brain, because he also
twice described the grid leak resistor as a negative feedback network;
interestingly, none of the other siliconitis sufferers afflicting us
know enough about tube circuits to correct this gross error by
Pearce.)

The designs are discussed in these texts:
http://members.lycos.co.uk.cob-web.o...mp%20INDEX.htm


If you and Arny really want to play in our sandbox,
at least do your homework first.

They don't want to play in our sandbox. They want to **** in it, to
suck the jam from our doughnut, to drain the glee from our hobby. It
offends these grim witchfinders that we are having fun.


A copy to UKRA so Pearce can't say I knock him behind his back. -- AJ


Gotta give credit where credit is due, Andre, even if it is only 1 dB.
The 100 ohm potmeter, shunted by both 100 ohms resistors, provide a
very tiny amount of local cathode feedback.

I didn't say it wasn't *also* a feedback circuit to some
fractional extent. What I said was that the public
idiot Don "Bluster" Pearce mistook the AC humbuster circuit for
solely a feedback circuit, and missed its primary purpose. What I said
was that the public idiot Don "Bluster" Pearce mistook the grid leak
circuit for a feedback circuit. What I said was the public idiot
Don "Bluster" Pearce clearly knows buggerall about tube circuits
and should therefore keep his nose out of what he is totally
ignorant about. Bluster Pearce has run away now to shelter
behind his killfile, so the rest of us can get on with the business
of tubes.

- Maggies are an addiction for life. -

Coca-cola is cheaper.

Always wanted to say that...

Andre Jute
The definition of darwinian accident waiting to happen: Don "Bluster"
Pearce.

[Eeyore]

Andre Jute wrote:

Sander deWaal wrote:

Gotta give credit where credit is due, Andre, even if it is only 1 dB.
The 100 ohm potmeter, shunted by both 100 ohms resistors, provide a
very tiny amount of local cathode feedback.

I didn't say it wasn't *also* a feedback circuit to some
fractional extent. What I said was that the public
idiot Don "Bluster" Pearce mistook the AC humbuster circuit for
solely a feedback circuit

That sounds remarkably unlikely !

Graham

[Chris Hornbeck]

On Fri, 19 Jan 2007 01:10:38 -0600, flipper wrote:

I understand your explanation but I don't understand why that doesn't
introduce the same voltage differential (larger actually because of
the AC peaks) but varying between opposite extremes at 60Hz rather
than 'DC'.

I don't mean thermal emissions but the cathode voltage distribution vs
grid you were speaking of.

Excellent question, perfectly expressed.

With AC heating all physical points of the filament/cathode
have an instantaneous average of zero volts grid-cathode due
to the heating voltage. This occurs by definition from
the "hum nulling", and is true however the nulling is done.

To say it backwards, if the heating voltage could appear
as grid-cathode voltage it would appear as hum.

It's a subtle point and yours is a very perceptive
question. Much thanks,

And thanks to all for a real r.a.t thread,

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

[Eeyore]

Chris Hornbeck wrote:

On Fri, 19 Jan 2007 01:10:38 -0600, flipper wrote:

I understand your explanation but I don't understand why that doesn't
introduce the same voltage differential (larger actually because of
the AC peaks) but varying between opposite extremes at 60Hz rather
than 'DC'.

I don't mean thermal emissions but the cathode voltage distribution vs
grid you were speaking of.

Excellent question, perfectly expressed.

With AC heating all physical points of the filament/cathode
have an instantaneous average of zero volts grid-cathode due
to the heating voltage.

But not a geometric average.

Graham

[Chris Hornbeck]

On Sun, 21 Jan 2007 01:44:36 +0000, Eeyore
wrote:

With AC heating all physical points of the filament/cathode
have an instantaneous average of zero volts grid-cathode due
to the heating voltage.

But not a geometric average.

?? What usage do you mean for "geometric"? We're assuming
a physically symmetrical geometry here, because it's
necessary for linearity. Something else?

More, more,

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

[Eeyore]

Chris Hornbeck wrote:

On Sun, 21 Jan 2007 01:44:36 +0000, Eeyore
wrote:

With AC heating all physical points of the filament/cathode
have an instantaneous average of zero volts grid-cathode due
to the heating voltage.

But not a geometric average.

?? What usage do you mean for "geometric"?

http://en.wikipedia.org/wiki/Geometric_Average

We're assuming
a physically symmetrical geometry here, because it's
necessary for linearity. Something else?

More, more,

Just because the voltage averages ( simple arithmetic average or mean ) to zero
doesn't mean it has no effect. It modulates the effective Vgk as Vgk vs Ia isn't
a perfectly linear term.

Graham

[Chris Hornbeck]

On Sun, 21 Jan 2007 02:59:12 +0000, Eeyore
wrote:

Just because the voltage averages ( simple arithmetic average or mean ) to zero
doesn't mean it has no effect. It modulates the effective Vgk as Vgk vs Ia isn't
a perfectly linear term.

My argument is a simple reductio ad absurdum. If nulled AC
heating voltage modulates Vgk then it's not nulled; like that.
I know it's not very elegant, but I can't see any way around
believing it.

DC heating does "modulate" Vgk to some small amount, by warping
geometry (just like on Star Trek!); mostly not enough to lose sleep
over, but that's Usenet discussions...

Might be less of a stretch to start from the position of a
filament with one end at signal ground, then "hum-nulling hum"
added into the grid voltage (a device revived here on r.a.t
by the sainted much-missed Steve Bench). This extreme case
has all physical points of the filament at wildly improbable
instantaneous voltages.

And because this thought device exaggerates the independence
of AC heating voltage from Vgk it simplifies the otherwise
sticky issue.

Much thanks, as always,

Chris Hornbeck
"History consists of truths which in the end turn into lies,
while myth consists of lies which finally turn into truths."
- Jean Cocteau

[Peter Wieck]

Andrew Jute McCoy exuded more lies:

I didn't say it wasn't *also* a feedback circuit to some
fractional extent.

Either it is ZNF or it is not. Now that you have admitted that it is
not, then you have also admitted to all the rest of your lies... Not
the least of which is that you actually have an amp, rather than a
concatenation of loose parts and a bad schematic of a marginal plan of
a dysfunctional amp.

Show the amp. If Raymond can do it without fanfare, blather, pretense
or reams of crap, perhaps you can do it even _with_ all of that.

Peter Wieck
Wyncote, PA