[Andre Jute]

Patrick Turner wrote:

Andre remarked......

But I'm not talking about that miniscule amount of THD caused by the cap. I don't
care a damn how much it is. What I care about is the *composition* of the noise
left by the NFB required to stabilize the amp because it was designed to the wrong
paradigm in the first instance.

Christ, of course NFB doesn't "stabilize" the amp. I meant "silence
the amp". I made the same slip of the tongue once in an article in
Glass Audio, and looked a right fool for it, except that Dan Schmalle
treated me kindly in the letter the editor chose to publish (and damn
right too, the editor should be embarrassed for not picking up such an
obvious slip, that's what editors are for, to pick up behind their
writers).

Well, I guess there will always be someone who is worried about such a
thing as
the composition of noise as a result of applied NFB,

I like high voltages and high current and high loads so much, and I
work only with the best tubes, and I don't have to count the pennies
for other components, that I invariably start with a very silent amp
already. The by-effects of NFB thus became interesting to me because I
was searching for what made people edgy with one silent amp and not
with another silent amp, when both had THD well below the level of
conscious perception. It had to be something about the composition of
the residual noise. The subliminal effect of NFB I discovered is now
widely accepted among the ultrafidelista; it is not a matter of faith
but of repeatable experiment. You have yourself often enough agreed
with one of my other conclusions from the same set of panel tests:
that PP and SE don't matter, nor DHT or trioded penttode, but only
that the sound should be in Class A1, made by some kind of natural or
hogtied triode, and have no or very modest levels of NFB. And surely
you have had the experience of the sound gurgling down the round
filing cabinet when you apply more NFB than the correct amount. Why do
you think that is? I have an answer that I can prove to an accepted
scientific standard: the composition of the residual.

which BTW, is never
applied to make an amp stable.

I know, Patrick. My English just slipped. It isn't my first language,
not by half a dozen. It is most politically incorrect for you to
mention itG.

[lot of interesting stuff snipped because I have to work instead of
writing letters on the net]

No wonder english is a difficult language to learn.

For you, perhaps. I did it twice and found each time that the effort
rewarded me richly.

Patrick Turner.

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

[Patrick Turner]

Andre Jute wrote:

Patrick Turner wrote:

Andre remarked......

But I'm not talking about that miniscule amount of THD caused by the cap. I don't
care a damn how much it is. What I care about is the *composition* of the noise
left by the NFB required to stabilize the amp because it was designed to the wrong
paradigm in the first instance.

Christ, of course NFB doesn't "stabilize" the amp. I meant "silence
the amp". I made the same slip of the tongue once in an article in
Glass Audio, and looked a right fool for it, except that Dan Schmalle
treated me kindly in the letter the editor chose to publish (and damn
right too, the editor should be embarrassed for not picking up such an
obvious slip, that's what editors are for, to pick up behind their
writers).

Well, I guess there will always be someone who is worried about such a
thing as
the composition of noise as a result of applied NFB,

I like high voltages and high current and high loads so much, and I
work only with the best tubes, and I don't have to count the pennies
for other components, that I invariably start with a very silent amp
already.

Its how I like to build amps, even the solid state ones.

The by-effects of NFB thus became interesting to me because I
was searching for what made people edgy with one silent amp and not
with another silent amp, when both had THD well below the level of
conscious perception. It had to be something about the composition of
the residual noise.

Perhaps so, but then the residual noise can be almost unmeasurable...

The subliminal effect of NFB I discovered is now
widely accepted among the ultrafidelista; it is not a matter of faith
but of repeatable experiment. You have yourself often enough agreed
with one of my other conclusions from the same set of panel tests:
that PP and SE don't matter, nor DHT or trioded penttode, but only
that the sound should be in Class A1, made by some kind of natural or
hogtied triode, and have no or very modest levels of NFB. And surely
you have had the experience of the sound gurgling down the round
filing cabinet when you apply more NFB than the correct amount. Why do
you think that is? I have an answer that I can prove to an accepted
scientific standard: the composition of the residual.

Well, I have experienced inexplicable differences in tube preamp tubes
which all have operating thd levels less than 0.01%, and noiseless
operation and
less than 6dB of any external FB anywhere.

I've given up finding out exactly why the gathered listeners could hear
the differenecs,
but triodes seem to have magic, which I just accept.

I have often though subtle microphonic effects could explain a lot.

which BTW, is never
applied to make an amp stable.

I know, Patrick. My English just slipped. It isn't my first language,
not by half a dozen. It is most politically incorrect for you to
mention itG.

Some engineers would disagree with me and tell me NFB IS applied to
stabilize
the unstable item, its part of its effect to cure all evils.
But in audio amps usually the stability is maximum without any loop FB,
and applying some FB rapidly reduces the margin of stability.
It only takes 6dB of global FB around a poor quality amp and when a cap
load is connected,
it soon becomes an oscillator.

[lot of interesting stuff snipped because I have to work instead of
writing letters on the net]

No wonder english is a difficult language to learn.

For you, perhaps. I did it twice and found each time that the effort
rewarded me richly.

Patrick Turner.

Ozian is also hard...

Patrick Turner.

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

[Iain Churches]

"Patrick Turner" wrote in message
...


Andre Jute wrote:
No wonder english is a difficult language to learn.

For you, perhaps. I did it twice and found each time that the effort
rewarded me richly.


Ozian is also hard...

But not when compared with Finnish or Estonian.