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Don Pearce Don Pearce is offline
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Jorden Verwer wrote:
Don Pearce wrote:
Jorden Verwer wrote:
JosephKK wrote:
Noise-like phenomena, in increasing order of bandwith:
Offset == 1/f noise == white noise

OK alligator, where does shot noise fall in the spectrum?
I never claimed that the list was exhausistive, but to answer your

question:
I would put it between 1/f noise and white noise.


The spectrum of shot noise is white - why would it be otherwise?

Shot noise will always be band limited because electrons have a nonzero
transit time. Its bandwith is very high, but not infinite.



Not helpful - in audio terms and a long, long way beyond, it is white.

d
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Kevin Aylward[_3_] Kevin Aylward[_3_] is offline
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JosephKK wrote:
On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer"
wrote:

Eeyore wrote:
given that you've apparently never heard of the term
offset.

Offset is IRRELEVANT to output devices you complete MORON !

I know that, and I never claimed otherwise. Offset is a form of
noise, in a sense. And like noise, it is caused almost completely by
the input transistors. I'm well aware of all that.

Do do you know what a 'closed loop' means ?

Yes.


Offset is a form of noise???? This is the first time i have ever
heard that.


Not for me. Its very common interpretation.

There is no engineering reason to look at it that way.


There is to me, and to many others.

is fundamentally a different property with different physics.


Offset is an error. Noise is an error. For example, the standard method of
analysing Sigma-Delta converters is to treat what is, technically, an error
in coding a signal from its actual value, as an additional *noise* source,
that is considered to be unrelated to the signal, when in fact, it is!

I don't see that it matters much where the error comes from, it can be
handled in the same general way.

Kevin Aylward

www.kevinaylward.co.uk


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JosephKK wrote:
On Fri, 19 Sep 2008 15:21:19 GMT, "Kevin Aylward"
wrote:

it.

Not at all in any remote way shape or form.
Don't you at least agree there are many similarities between 1/f
noise and offset?



Actually, I do. By and large, they amount to the same thing. Its all
low frequency variations. For example, if one designs a chopper amp
to get low offset, it also kills/corrects for 1/f noise as well. If
one has 1/f problems in an system, one immediately thinks about
using a chopper..well I do any way...


Kevin Aylward
www.anasoft.co.uk
SuperSpice


I am less sure about it killing 1/f (flicker) noise rather than band
shifting it to a place where is can be filtered out. It is not
offset, though the chopper amplifiers can mask it out.


I don't see who its physical possible to distinguish between a random dc
offset, and random noise. If offset is completely fixed, never moves with
time, we can ignore it as we can just subtract it with certainty. Its only
if it moves that it concerns us, well, except for having 1A continuous
through a speaker coil....

Ah, yes, noise
shaping; making some undesired near band interfering signal content
terms go where they are easier to separate from the desired signal.


already addressed by the other fellows post.

Kevin Aylward

www.kevinaylward.co.uk


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Don Pearce Don Pearce is offline
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Kevin Aylward wrote:
JosephKK wrote:
On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer"
wrote:

Eeyore wrote:
given that you've apparently never heard of the term
offset.
Offset is IRRELEVANT to output devices you complete MORON !
I know that, and I never claimed otherwise. Offset is a form of
noise, in a sense. And like noise, it is caused almost completely by
the input transistors. I'm well aware of all that.

Do do you know what a 'closed loop' means ?
Yes.

Offset is a form of noise???? This is the first time i have ever
heard that.


Not for me. Its very common interpretation.

There is no engineering reason to look at it that way.


There is to me, and to many others.

is fundamentally a different property with different physics.


Offset is an error. Noise is an error. For example, the standard method of
analysing Sigma-Delta converters is to treat what is, technically, an error
in coding a signal from its actual value, as an additional *noise* source,
that is considered to be unrelated to the signal, when in fact, it is!

I don't see that it matters much where the error comes from, it can be
handled in the same general way.

Kevin Aylward

www.kevinaylward.co.uk



It can be handled the same way, but doesn't need to be. Noise must be
handled by filtering, with with a specific inline filter or effective
filtering by means of a control loop. DC will also be handled that way,
but for DC there is always the option of trimming it away with either an
adjustable or an SOT. You can't do that with noise, which makes them
fundamentally different things.

d
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In article , Rich Grise wrote:
On Wed, 24 Sep 2008 08:33:17 -0400, Arny Krueger wrote:
"Eeyore" wrote in
I expect the phone would be good enough for you ?


Depends on the phone. If I make a phone up out of a good vocal mic and some
studio monitors, it will be pretty good. These days really good electret
mics cost pennies, while good earphone elements are relatively small and
cheap compared to speakers. Most of the inherent losses in modern phones are
in the communications channel, which is wildly bandwidth-reduced. As
bandwidth becomes cheaper, there is a possibility that good-sounding
telephones will become commonplace.


If NASA can send broadcast quality video down from the shuttle or ISS,
howcome their audio still sounds like a fast food clown?

Thanks,
Rich

I don't know whats used today, but the Apollo stuff used Motorola communications
units much the same as standard variety sets. Those were also on a separate antenna
system from the unified S Band. Those bandwidths also were much the same as standard
communication links inside the tracking sites and links to mission control.

greg


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Randy Yates Randy Yates is offline
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Don Pearce writes:

Jorden Verwer wrote:
Don Pearce wrote:
Jorden Verwer wrote:
JosephKK wrote:
Noise-like phenomena, in increasing order of bandwith:
Offset == 1/f noise == white noise

OK alligator, where does shot noise fall in the spectrum?
I never claimed that the list was exhausistive, but to answer your

question:
I would put it between 1/f noise and white noise.


The spectrum of shot noise is white - why would it be otherwise?

Shot noise will always be band limited because electrons have a nonzero
transit time. Its bandwith is very high, but not infinite.



Not helpful - in audio terms and a long, long way beyond, it is white.


Don,

Perhaps your definition of white is different than mine. There are two
I've seen: one says pretty much directly that it is noise with infinite
bandwidth, and the other implies it through the relationship of a Dirac
delta function (the autocorrelation function of an uncorrelated white
noise process) and the Fourier Transform. You can find those definitions
in this short paper on the unrelated topic of the DC value of white
noise:

http://www.digitalsignallabs.com/white.pdf

--Randy


--
% Randy Yates % "She has an IQ of 1001, she has a jumpsuit
%% Fuquay-Varina, NC % on, and she's also a telephone."
%%% 919-577-9882 %
%%%% % 'Yours Truly, 2095', *Time*, ELO
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Don Pearce wrote:

Kevin Aylward wrote:
JosephKK wrote:
On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer"
wrote:

Eeyore wrote:
given that you've apparently never heard of the term
offset.
Offset is IRRELEVANT to output devices you complete MORON !
I know that, and I never claimed otherwise. Offset is a form of
noise, in a sense. And like noise, it is caused almost completely by
the input transistors. I'm well aware of all that.

Do do you know what a 'closed loop' means ?
Yes.

Offset is a form of noise???? This is the first time i have ever
heard that.


Not for me. Its very common interpretation.

There is no engineering reason to look at it that way.


There is to me, and to many others.

is fundamentally a different property with different physics.


Offset is an error. Noise is an error. For example, the standard method of
analysing Sigma-Delta converters is to treat what is, technically, an error
in coding a signal from its actual value, as an additional *noise* source,
that is considered to be unrelated to the signal, when in fact, it is!

I don't see that it matters much where the error comes from, it can be
handled in the same general way.


It can be handled the same way, but doesn't need to be. Noise must be
handled by filtering, with with a specific inline filter or effective
filtering by means of a control loop. DC will also be handled that way,
but for DC there is always the option of trimming it away with either an
adjustable or an SOT. You can't do that with noise, which makes them
fundamentally different things.


And offset in an audio power amp is commonly corrected by not making it DC
coupled. A filter of sorts I suppose.

Graham

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Randy Yates wrote:
Don Pearce writes:

Jorden Verwer wrote:
Don Pearce wrote:
Jorden Verwer wrote:
JosephKK wrote:
Noise-like phenomena, in increasing order of bandwith:
Offset == 1/f noise == white noise

OK alligator, where does shot noise fall in the spectrum?
I never claimed that the list was exhausistive, but to answer your
question:
I would put it between 1/f noise and white noise.


The spectrum of shot noise is white - why would it be otherwise?
Shot noise will always be band limited because electrons have a nonzero
transit time. Its bandwith is very high, but not infinite.


Not helpful - in audio terms and a long, long way beyond, it is white.


Don,

Perhaps your definition of white is different than mine. There are two
I've seen: one says pretty much directly that it is noise with infinite
bandwidth, and the other implies it through the relationship of a Dirac
delta function (the autocorrelation function of an uncorrelated white
noise process) and the Fourier Transform. You can find those definitions
in this short paper on the unrelated topic of the DC value of white
noise:

http://www.digitalsignallabs.com/white.pdf

--Randy



My definition of white noise is that equal bandwidths contain equal
energy, whatever their centre frequency. Certainly over the full extent
of the audio band, and as I say a very long way beyond, that is true for
shot noise.

There is a sentence in that paper that shows the limitation of
Papoulis's theory in that it cannot of itself show that white noise has
a zero mean (no DC component). I think the pragmatic definition is
probably the more useful and easily understood.

d
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Don Pearce Don Pearce is offline
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Eeyore wrote:

Don Pearce wrote:

Kevin Aylward wrote:
JosephKK wrote:
On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer"
wrote:

Eeyore wrote:
given that you've apparently never heard of the term
offset.
Offset is IRRELEVANT to output devices you complete MORON !
I know that, and I never claimed otherwise. Offset is a form of
noise, in a sense. And like noise, it is caused almost completely by
the input transistors. I'm well aware of all that.

Do do you know what a 'closed loop' means ?
Yes.

Offset is a form of noise???? This is the first time i have ever
heard that.
Not for me. Its very common interpretation.

There is no engineering reason to look at it that way.
There is to me, and to many others.

is fundamentally a different property with different physics.
Offset is an error. Noise is an error. For example, the standard method of
analysing Sigma-Delta converters is to treat what is, technically, an error
in coding a signal from its actual value, as an additional *noise* source,
that is considered to be unrelated to the signal, when in fact, it is!

I don't see that it matters much where the error comes from, it can be
handled in the same general way.

It can be handled the same way, but doesn't need to be. Noise must be
handled by filtering, with with a specific inline filter or effective
filtering by means of a control loop. DC will also be handled that way,
but for DC there is always the option of trimming it away with either an
adjustable or an SOT. You can't do that with noise, which makes them
fundamentally different things.


And offset in an audio power amp is commonly corrected by not making it DC
coupled. A filter of sorts I suppose.

Graham


I think that since these days 99% of audio amps are configured as op
amps, DC offset is most commonly handled by the feedback loop - the
second kind I listed.

d
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Eeyore Eeyore is offline
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Don Pearce wrote:

Eeyore wrote:
Don Pearce wrote:
Kevin Aylward wrote:
JosephKK wrote:
On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer"
wrote:

Eeyore wrote:
given that you've apparently never heard of the term
offset.
Offset is IRRELEVANT to output devices you complete MORON !
I know that, and I never claimed otherwise. Offset is a form of
noise, in a sense. And like noise, it is caused almost completely by
the input transistors. I'm well aware of all that.

Do do you know what a 'closed loop' means ?
Yes.

Offset is a form of noise???? This is the first time i have ever
heard that.
Not for me. Its very common interpretation.

There is no engineering reason to look at it that way.
There is to me, and to many others.

is fundamentally a different property with different physics.
Offset is an error. Noise is an error. For example, the standard method of
analysing Sigma-Delta converters is to treat what is, technically, an error
in coding a signal from its actual value, as an additional *noise* source,
that is considered to be unrelated to the signal, when in fact, it is!

I don't see that it matters much where the error comes from, it can be
handled in the same general way.
It can be handled the same way, but doesn't need to be. Noise must be
handled by filtering, with with a specific inline filter or effective
filtering by means of a control loop. DC will also be handled that way,
but for DC there is always the option of trimming it away with either an
adjustable or an SOT. You can't do that with noise, which makes them
fundamentally different things.


And offset in an audio power amp is commonly corrected by not making it DC
coupled. A filter of sorts I suppose.


I think that since these days 99% of audio amps are configured as op
amps, DC offset is most commonly handled by the feedback loop - the
second kind I listed.


Gross offset from mismatched power devices, yes. I was thinking of that from the
input pair. Of course lateral fets aren't subject to the gross offset problem.

Graham



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Don Pearce Don Pearce is offline
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Eeyore wrote:

Don Pearce wrote:

Eeyore wrote:
Don Pearce wrote:
Kevin Aylward wrote:
JosephKK wrote:
On Thu, 18 Sep 2008 18:26:25 -0000, "Jorden Verwer"
wrote:

Eeyore wrote:
given that you've apparently never heard of the term
offset.
Offset is IRRELEVANT to output devices you complete MORON !
I know that, and I never claimed otherwise. Offset is a form of
noise, in a sense. And like noise, it is caused almost completely by
the input transistors. I'm well aware of all that.

Do do you know what a 'closed loop' means ?
Yes.

Offset is a form of noise???? This is the first time i have ever
heard that.
Not for me. Its very common interpretation.

There is no engineering reason to look at it that way.
There is to me, and to many others.

is fundamentally a different property with different physics.
Offset is an error. Noise is an error. For example, the standard method of
analysing Sigma-Delta converters is to treat what is, technically, an error
in coding a signal from its actual value, as an additional *noise* source,
that is considered to be unrelated to the signal, when in fact, it is!

I don't see that it matters much where the error comes from, it can be
handled in the same general way.
It can be handled the same way, but doesn't need to be. Noise must be
handled by filtering, with with a specific inline filter or effective
filtering by means of a control loop. DC will also be handled that way,
but for DC there is always the option of trimming it away with either an
adjustable or an SOT. You can't do that with noise, which makes them
fundamentally different things.
And offset in an audio power amp is commonly corrected by not making it DC
coupled. A filter of sorts I suppose.

I think that since these days 99% of audio amps are configured as op
amps, DC offset is most commonly handled by the feedback loop - the
second kind I listed.


Gross offset from mismatched power devices, yes. I was thinking of that from the
input pair. Of course lateral fets aren't subject to the gross offset problem.

Graham


All depends how the input stage is configured. If the actual input
transistor is suitably grounded at its based, and the feedback returns
to the base of its Blumlein partner, then all offsets through the entire
amplifier chain get added together and corrected as a single item,
resulting in the speaker terminal at zero volts, just like the first
transistor base.

Actually this isn't quite true since that base is offset slightly
negative by the base current through the several k resistor.

Individual internal nodes will still be non-zero, of course, but if we
treat the amplifier as a black box, with only input and output terminals
visible, the net offset is always efectively zero. Or rather whatever
they would have been if uncorrected divided by the open loop DC gain of
the amplifier.

d
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Randy Yates Randy Yates is offline
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Don Pearce writes:
[...]
My definition of white noise is that equal bandwidths contain equal
energy, whatever their centre frequency. Certainly over the full
extent of the audio band, and as I say a very long way beyond, that is
true for shot noise.


I agree that shot noise is constant in some bandwidth around a centre
frequency that extends "a very long way beyond" the audio band. What I
am saying is that, even though the term "white noise" is used
colloquially to mean "constant power over some large bandwidth," that
usage is wrong according to the definition.

It would be useful to coin a new phrase for such bandlimited noise;
"bandlimited white noise"?

There is a sentence in that paper that shows the limitation of
Papoulis's theory in that it cannot of itself show that white noise
has a zero mean (no DC component).


That was the point of both sections: neither Papoulis' nor Brown's
definitions imply zero mean.

I think the pragmatic definition is probably the more useful and
easily understood.


I would agree that myself and pretty much everyone else here understands
what is meant by "white" in this context.

What I do not agree with is when someone such as Jordan is careful with
the terminology and meets with resistance. Jordan is not wrong for using
the term "white noise" in its proper form!
--
% Randy Yates % "She's sweet on Wagner-I think she'd die for Beethoven.
%% Fuquay-Varina, NC % She love the way Puccini lays down a tune, and
%%% 919-577-9882 % Verdi's always creepin' from her room."
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Don Pearce Don Pearce is offline
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Randy Yates wrote:
Don Pearce writes:
[...]
My definition of white noise is that equal bandwidths contain equal
energy, whatever their centre frequency. Certainly over the full
extent of the audio band, and as I say a very long way beyond, that is
true for shot noise.


I agree that shot noise is constant in some bandwidth around a centre
frequency that extends "a very long way beyond" the audio band. What I
am saying is that, even though the term "white noise" is used
colloquially to mean "constant power over some large bandwidth," that
usage is wrong according to the definition.

That wouldn't be my usage - mine is that it is constant within any
selected small bandwidths, as long as they are the same. If you measure
the noise power over, say half the audio band in one hit, you have no
way of judging whether or not it is white. Far better would be to use,
say, 10Hz bandwidth measured at manyb centre frequencies from 20Hz to 20kHz.

It would be useful to coin a new phrase for such bandlimited noise;
"bandlimited white noise"?


I'm happy with banlimited white noise, provided that the limited band in
question contains everything you are trying to measure. If it doesn't
then you can't really use white to describe it.

There is a sentence in that paper that shows the limitation of
Papoulis's theory in that it cannot of itself show that white noise
has a zero mean (no DC component).


That was the point of both sections: neither Papoulis' nor Brown's
definitions imply zero mean.

I think the pragmatic definition is probably the more useful and
easily understood.


I would agree that myself and pretty much everyone else here understands
what is meant by "white" in this context.


I thing white in an audio context is easy enough to understand - my
first paragraph in my reply covers it.

What I do not agree with is when someone such as Jordan is careful with
the terminology and meets with resistance. Jordan is not wrong for using
the term "white noise" in its proper form!


Agreed

d
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Don Pearce wrote:
It can be handled the same way, but doesn't need to be. Noise must be
handled by filtering, with with a specific inline filter or effective
filtering by means of a control loop. DC will also be handled that way,
but for DC there is always the option of trimming it away with either an
adjustable or an SOT. You can't do that with noise, which makes them
fundamentally different things.

Trimming will only cancel the offset that is present at that instant. When
it drifts (and it will), you will experience offset again. Adjustable
trimming solutions can be viewed as very low bandwidth control loops (with
the person doing the adjustments closing the loop). There is no fundamental
difference.


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Don Pearce wrote:

Eeyore wrote:
Don Pearce wrote:
Eeyore wrote:
Don Pearce wrote:
Kevin Aylward wrote:

I don't see that it matters much where the error comes from, it can be
handled in the same general way.
It can be handled the same way, but doesn't need to be. Noise must be
handled by filtering, with with a specific inline filter or effective
filtering by means of a control loop. DC will also be handled that way,
but for DC there is always the option of trimming it away with either an
adjustable or an SOT. You can't do that with noise, which makes them
fundamentally different things.
And offset in an audio power amp is commonly corrected by not making it DC
coupled. A filter of sorts I suppose.
I think that since these days 99% of audio amps are configured as op
amps, DC offset is most commonly handled by the feedback loop - the
second kind I listed.


Gross offset from mismatched power devices, yes. I was thinking of that from the
input pair. Of course lateral fets aren't subject to the gross offset problem.


All depends how the input stage is configured. If the actual input
transistor is suitably grounded at its based, and the feedback returns
to the base of its Blumlein partner, then all offsets through the entire
amplifier chain get added together and corrected as a single item,
resulting in the speaker terminal at zero volts, just like the first
transistor base.

Actually this isn't quite true since that base is offset slightly
negative by the base current through the several k resistor.


Which is hopefully matched by the feedback circuit resistance.


Individual internal nodes will still be non-zero, of course, but if we
treat the amplifier as a black box, with only input and output terminals
visible, the net offset is always efectively zero. Or rather whatever
they would have been if uncorrected divided by the open loop DC gain of
the amplifier.


Indeed.

Graham



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Jorden Verwer wrote:

Don Pearce wrote:
It can be handled the same way, but doesn't need to be. Noise must be
handled by filtering, with with a specific inline filter or effective
filtering by means of a control loop. DC will also be handled that way,
but for DC there is always the option of trimming it away with either an
adjustable or an SOT. You can't do that with noise, which makes them
fundamentally different things.

Trimming will only cancel the offset that is present at that instant. When
it drifts (and it will), you will experience offset again. Adjustable
trimming solutions can be viewed as very low bandwidth control loops (with
the person doing the adjustments closing the loop). There is no fundamental
difference.


My experience is that the DC offset in an audio amp is set for all practical
purposes by the typical input long-tailed pair and this is readily trimmed if
required by a pot. Or even a servo circuit with a longish time constant. Any
drift is most likely to be thermal hence devices like the LM394 and the old
practice of glueing 2 TO-92 devices dack-to back.

Graham


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"Eeyore" wrote in
message
Arny Krueger wrote:

"Eeyore" wrote
Arny Krueger wrote:
"Eeyore" wrote:
Arny Krueger wrote:

I have more highly sensitive audio test gear by
accident then most people have on purpose. I probably
shouldn't admit this because it shows a certain kind
of carelessness.

Not more sensitive than Audio Precision or Prism
Sound.


Better than a Prism Sound ADA-8


Which isn't test equipment anyway.


Well, yes and no. With computer testing software, any
ADC-DAC can perform as some kind of audio test equipment.


Besides, I'm not the one who brought Prism up.

or an AP System One.


Better than a brilliant 20+ year old design ? No longer
in production btw. It's System 2 now. I'd like to know
by how much to be honest.


The LynxTwo runs neck-and-neck with an AP System 2,
according to its designer who of course has one.


So not actually 'better' then ?


Testing a LynxTwo with an AP2 won't give an answer either way, for obvious
reasons.

I seem to remember that the designer said that my www.pcavtech.com results
for the LynxTwo were significantly better than what he got while measuring
it with an AP2.


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"Arny Krueger" wrote in message
. ..
I seem to remember that the designer said that my www.pcavtech.com results
for the LynxTwo were significantly better than what he got while measuring
it with an AP2.


But he must have already done his own loop back tests surely?
You don't get results like that by accident :-)

MrT.


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Eeyore wrote:

John Larkin wrote:

True, none of this is relevant for audio. Anything will work for
audio.


Almost anything. RCA's 2N3055s weren't exactly the fastest in the world. 800kHz
fT IIRC. I hate to think what their germanium predecessors like the OC35 were
like.

Graham



The 3055 was developed for linear power supplies, so it didn't need a
high fT. It was scaled down from the RCA 40411, which was a 100 volt
device, VS a 60 volt, cheaper device. The 40411 was used in some audio
amps in some early RCA semiconductor data books. In fact, the 60 watt
amplifier used the 40406, 40407, 40408, 40409, 40410, and a pair of
40411 transistors, and a couple diodes to sense the temperature of the
heatsinks. I built a PA amp from that sample design in the late '60s.
It, and a preamp were also built on my first hand made PC boards.


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"Michael A. Terrell" wrote:

Eeyore wrote:
John Larkin wrote:

True, none of this is relevant for audio. Anything will work for
audio.


Almost anything. RCA's 2N3055s weren't exactly the fastest in the world. 800kHz
fT IIRC. I hate to think what their germanium predecessors like the OC35 were
like.


The 3055 was developed for linear power supplies, so it didn't need a
high fT.


True enough, except Motorola's were faster anyway. Using the wrong brand in hobby
kits caused many a burnt out output stage.

Eventually I think the slower parts got an H suffix as in RCA's 'hometaxial' process.



It was scaled down from the RCA 40411, which was a 100 volt
device, VS a 60 volt, cheaper device. The 40411 was used in some audio
amps in some early RCA semiconductor data books. In fact, the 60 watt
amplifier used the 40406, 40407, 40408, 40409, 40410, and a pair of
40411 transistors, and a couple diodes to sense the temperature of the
heatsinks. I built a PA amp from that sample design in the late '60s.
It, and a preamp were also built on my first hand made PC boards.


I know the very one and still have that handbook. I built one too. The little
heatsinks welded onto the drivers were an intriguing novelty that never caught on.

In the UK, WEM 100W PA and instrument amps were based on that design for years. They
got 100W by using 6 ohm speakers !

Graham



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"Michael A. Terrell" wrote in
message m
Eeyore wrote:

John Larkin wrote:

True, none of this is relevant for audio. Anything will
work for audio.


Almost anything. RCA's 2N3055s weren't exactly the
fastest in the world. 800kHz fT IIRC. I hate to think
what their germanium predecessors like the OC35 were
like.


RCA's germanium predecessor to the 2N3055 was arguably the 2N2147. If
memory serves, PD = 25 watts, FT = 3 MHz. SOA = negligible. Many of the
first generation mass-market *production* hi fi power amps used the 2N2147
with a driver transformer. This included Knight Kit, Heath Kit, Ten Tec,
Altec Lansing, etc. Mainstream mid-fi producers like H. H. Scott, Sherwood,
and Fisher AFAIK never produced any germanium power amps. Their first
generation products were based on 2N3055 and similar devices.

The 3055 was developed for linear power supplies, so it
didn't need a high fT.


AFAIK the first generation data sheets characterized it as both a power
supply, servo amp, and audio power amp device.

It was scaled down from the RCA 40411, which was a 100 volt device, VS a
60 volt, cheaper
device.


AFAIK the 40411 was introduced several years after the introduction of the
2N3055. I think that there were at least two years of the RCA solid state
book with the 2N305x family in them, before the 404xx family was added.

I had a business partner who, in an earlier venture manufactured SS power
amps for professional use. He based his top-of-the-line products on the
40411. There was also an even more robust device called the 411. Again, my
memory of this is hazy as this was in the late 60s.

According to him, he discovered that the 404xx series of devices were mostly
sold for automotive uses, such as SS ignition modules. For a while RCA was
making these parts literally by the millions. Product consistency was a
problem, which they were very effective at exploiting. The
middle-of-the-road parts went to the car companies under proprietary part
numbers.

The really nice parts, the cream of the crop, were skimmed off sold in
relatively small volumes as 40411s, mostly for audio. Eventually the car
market for 40411-type devices dried up. As the milk dried up, so did the
cream.

According to my friend, RCA tried various ruses to come up with enough
40411-type devices, but could never equal their original product. He sold a
ton of amps that were not durable and was forced out of business.
Eventually, he started cutting open devices, both old and new, and found
results similar to what we've seen far more recently with counterfeit
transistors.. It was his opinion that RCA was sort of counterfeiting their
own product.

This all happened number of decades ago, and should not be taken as a
reflection on the current RCA corp which has been bought and sold at least
once since then, and is thus under a different management.


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Arny Krueger wrote:

According to my friend, RCA tried various ruses to come up with enough
40411-type devices, but could never equal their original product. He sold a
ton of amps that were not durable and was forced out of business.
Eventually, he started cutting open devices, both old and new, and found
results similar to what we've seen far more recently with counterfeit
transistors.. It was his opinion that RCA was sort of counterfeiting their
own product.


Seen that with the RCA410 too which they sold as replacement MJ410s. It took
thumbscrews to get them to admit they contained dies from 3 seperate lines. A
bright tech noticed by the way that there were 3 'hard codes' stamped on the
case and 2 of them gave trouble.

The 410s were just used as fastish drivers, we were using the 2N3773 by then as
main output devices. Seemed solid enough. If they'd been around at the time,
they might have saved your friend's company.

Graham

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Arny Krueger wrote:

"Michael A. Terrell" wrote in
message m
Eeyore wrote:

John Larkin wrote:

True, none of this is relevant for audio. Anything will
work for audio.

Almost anything. RCA's 2N3055s weren't exactly the
fastest in the world. 800kHz fT IIRC. I hate to think
what their germanium predecessors like the OC35 were
like.


RCA's germanium predecessor to the 2N3055 was arguably the 2N2147. If
memory serves, PD = 25 watts, FT = 3 MHz. SOA = negligible. Many of the
first generation mass-market *production* hi fi power amps used the 2N2147
with a driver transformer. This included Knight Kit, Heath Kit, Ten Tec,
Altec Lansing, etc. Mainstream mid-fi producers like H. H. Scott, Sherwood,
and Fisher AFAIK never produced any germanium power amps. Their first
generation products were based on 2N3055 and similar devices.

The 3055 was developed for linear power supplies, so it
didn't need a high fT.


AFAIK the first generation data sheets characterized it as both a power
supply, servo amp, and audio power amp device.

It was scaled down from the RCA 40411, which was a 100 volt device, VS a
60 volt, cheaper
device.


AFAIK the 40411 was introduced several years after the introduction of the
2N3055. I think that there were at least two years of the RCA solid state
book with the 2N305x family in them, before the 404xx family was added.



I bought some 40411 transistors in the '60s, and the product release
for the 2N3055 stated that it was developed as a 60 volt version for
linear power supplies. Pupular Electronics used the RCA sample circuit
for their 'Brute 70' amplifier.

http://www.swtpc.com/mholley/Popular...PE_Feb1967.htm


I had a business partner who, in an earlier venture manufactured SS power
amps for professional use. He based his top-of-the-line products on the
40411. There was also an even more robust device called the 411. Again, my
memory of this is hazy as this was in the late 60s.

According to him, he discovered that the 404xx series of devices were mostly
sold for automotive uses, such as SS ignition modules. For a while RCA was
making these parts literally by the millions. Product consistency was a
problem, which they were very effective at exploiting. The
middle-of-the-road parts went to the car companies under proprietary part
numbers.

The really nice parts, the cream of the crop, were skimmed off sold in
relatively small volumes as 40411s, mostly for audio. Eventually the car
market for 40411-type devices dried up. As the milk dried up, so did the
cream.

According to my friend, RCA tried various ruses to come up with enough
40411-type devices, but could never equal their original product. He sold a
ton of amps that were not durable and was forced out of business.
Eventually, he started cutting open devices, both old and new, and found
results similar to what we've seen far more recently with counterfeit
transistors.. It was his opinion that RCA was sort of counterfeiting their
own product.

This all happened number of decades ago, and should not be taken as a
reflection on the current RCA corp which has been bought and sold at least
once since then, and is thus under a different management.



--
http://improve-usenet.org/index.html

aioe.org, Goggle Groups, and Web TV users must request to be white
listed, or I will not see your messages.

If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm


There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.
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Default MOSFET output stage


Eeyore wrote:

Arny Krueger wrote:

According to my friend, RCA tried various ruses to come up with enough
40411-type devices, but could never equal their original product. He sold a
ton of amps that were not durable and was forced out of business.
Eventually, he started cutting open devices, both old and new, and found
results similar to what we've seen far more recently with counterfeit
transistors.. It was his opinion that RCA was sort of counterfeiting their
own product.


Seen that with the RCA410 too which they sold as replacement MJ410s. It took
thumbscrews to get them to admit they contained dies from 3 seperate lines. A
bright tech noticed by the way that there were 3 'hard codes' stamped on the
case and 2 of them gave trouble.

The 410s were just used as fastish drivers, we were using the 2N3773 by then as
main output devices. Seemed solid enough. If they'd been around at the time,
they might have saved your friend's company.

Graham



I used a lot of 2N3773 to replace 40411, and some other 100 volt
transistors. I think I still have one pair left in stock.


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listed, or I will not see your messages.

If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm


There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.
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Default MOSFET output stage



"Michael A. Terrell" wrote:

Eeyore wrote:
Arny Krueger wrote:

According to my friend, RCA tried various ruses to come up with enough
40411-type devices, but could never equal their original product. He sold a
ton of amps that were not durable and was forced out of business.
Eventually, he started cutting open devices, both old and new, and found
results similar to what we've seen far more recently with counterfeit
transistors.. It was his opinion that RCA was sort of counterfeiting their
own product.


Seen that with the RCA410 too which they sold as replacement MJ410s. It took
thumbscrews to get them to admit they contained dies from 3 seperate lines. A
bright tech noticed by the way that there were 3 'hard codes' stamped on the
case and 2 of them gave trouble.

The 410s were just used as fastish drivers, we were using the 2N3773 by then as
main output devices. Seemed solid enough. If they'd been around at the time,
they might have saved your friend's company.


I used a lot of 2N3773 to replace 40411, and some other 100 volt
transistors. I think I still have one pair left in stock.


They were such good replacements for almost all the (predominantly npn) output
devices of the day that I may have about half to a third of a tray of them lying
about somewhere still !

Graham



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"Michael A. Terrell" wrote:

Eeyore wrote:
Arny Krueger wrote:

According to my friend, RCA tried various ruses to come up with enough
40411-type devices, but could never equal their original product. He sold a
ton of amps that were not durable and was forced out of business.
Eventually, he started cutting open devices, both old and new, and found
results similar to what we've seen far more recently with counterfeit
transistors.. It was his opinion that RCA was sort of counterfeiting their
own product.


Seen that with the RCA410 too which they sold as replacement MJ410s. It took
thumbscrews to get them to admit they contained dies from 3 seperate lines. A
bright tech noticed by the way that there were 3 'hard codes' stamped on the
case and 2 of them gave trouble.

The 410s were just used as fastish drivers, we were using the 2N3773 by then as
main output devices. Seemed solid enough. If they'd been around at the time,
they might have saved your friend's company.


I used a lot of 2N3773 to replace 40411, and some other 100 volt
transistors. I think I still have one pair left in stock.


Oh and the 3773 had a 140V rating with correspondingly larger SOA IIRC.

Modern MJ1502Xs make it look silly now but it was THE high power audio output device
of the day.

Graham

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"Arny Krueger" wrote in message

"Michael A. Terrell" wrote in
message
m


It was scaled down from the RCA 40411, which was a 100
volt device, VS a 60 volt, cheaper
device.


AFAIK the 40411 was introduced several years after the
introduction of the 2N3055. I think that there were at
least two years of the RCA solid state book with the
2N305x family in them, before the 404xx family was added.


To shed a little more light:

http://www.ck722museum.com/history/r...isel_Page3.htm

"After several chip design changes and some significant package cost
reductions the 2N1486 and 2N1490 migrated into the 2N3054 and 2N3055 which
became industry workhorse standards. The package redesigns were done by Milt
Grimes. The 2N3055 was the first multi-amp silicon power transistor to sell
for less than one dollar! It was a huge success in the power supply market.
In 1965, the team of Design, Production, and Applications engineers who
launched these devices got RCA Electronic Components Achievement Awards,
which were quite generous."

I'm not an IEEE member, but this relevant article is online for those who
a

http://ieeexplore.ieee.org/Xplore/lo...rnumber=960371

"
The 2N3055: a case history
Ellis, J.N.; Osadchy, V.S.
Electron Devices, IEEE Transactions on
Volume 48, Issue 11, Nov 2001 Page(s):2477 - 2484
Digital Object Identifier 10.1109/16.960371

Summary:The 2N3055 power transistor was introduced by the Radio Corporation
of America (RCA) in the early 1960s. It was one of the first silicon power
transistors, offered unrivalled second breakdown immunity and found many
applications particularly in audio power amplifiers and linear power
supplies. Other companies tried to copy it with varying degrees of success:
one company acknowledges it now by naming a power MOSFET after it. We trace
its history, manufacture and eventual decline against pressure from
competing technologies. Modern simulation tools have been used to
investigate the operation of the device which illustrate its good, and not
so good, features. We also relate its geometry to a SPICE model. Neither of
these tools would have been available to the original developers. We propose
that this transistor be given a place in the archives of history, ranked
alongside other famous devices of the 20th century such as the 300B tube
"


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Arny Krueger wrote:

"Arny Krueger" wrote
"Michael A. Terrell" wrote in


It was scaled down from the RCA 40411, which was a 100
volt device, VS a 60 volt, cheaper
device.


AFAIK the 40411 was introduced several years after the
introduction of the 2N3055. I think that there were at
least two years of the RCA solid state book with the
2N305x family in them, before the 404xx family was added.


To shed a little more light:

http://www.ck722museum.com/history/r...isel_Page3.htm

"After several chip design changes and some significant package cost
reductions the 2N1486 and 2N1490 migrated into the 2N3054 and 2N3055 which
became industry workhorse standards. The package redesigns were done by Milt
Grimes. The 2N3055 was the first multi-amp silicon power transistor to sell
for less than one dollar! It was a huge success in the power supply market.
In 1965, the team of Design, Production, and Applications engineers who
launched these devices got RCA Electronic Components Achievement Awards,
which were quite generous."

I'm not an IEEE member, but this relevant article is online for those who
a

http://ieeexplore.ieee.org/Xplore/lo...rnumber=960371

"
The 2N3055: a case history
Ellis, J.N.; Osadchy, V.S.
Electron Devices, IEEE Transactions on
Volume 48, Issue 11, Nov 2001 Page(s):2477 - 2484
Digital Object Identifier 10.1109/16.960371

Summary:The 2N3055 power transistor was introduced by the Radio Corporation
of America (RCA) in the early 1960s. It was one of the first silicon power
transistors, offered unrivalled second breakdown immunity and found many
applications particularly in audio power amplifiers and linear power
supplies. Other companies tried to copy it with varying degrees of success:
one company acknowledges it now by naming a power MOSFET after it. We trace
its history, manufacture and eventual decline against pressure from
competing technologies. Modern simulation tools have been used to
investigate the operation of the device which illustrate its good, and not
so good, features. We also relate its geometry to a SPICE model. Neither of
these tools would have been available to the original developers. We propose
that this transistor be given a place in the archives of history, ranked
alongside other famous devices of the 20th century such as the 300B tube
"


Orange ? or was it Wem ? made probably the world's first SS 1kW amplifier using them IIRC. I
was called the Killerwatt or somesuch. Because the supply rails were so low the load had to be
something like one or two ohms, unheard of in those days, but acheived simply by multiple
paralleled speakers.

Graham


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