MOSFET output stage

[Eeyore]

Eeysore the Criminal Lunatic "


** Another blatant LIE !!

YOU just told everyone how these QSC amps have audible crossover distortion
!!!!!!!!!!!!!!

Which may simply be bad design unrelated to the biasing factor.

I can beat QSC's figures with zero large device quiescent.

Graham

 

[Vladimir Vassilevsky]

Phil,

You have a mental illness. You probably don't realize it, but it's obvious
to others. If you're not already doing so, for your own sake, you should
seek professional help.

So what. Anyone who participates in the newsgroups has a mental
disorder. Normal people have no interest for that; they have sex, pray
God, take precarious mortgages and watch TV. This is what they call
"having a life".

VLV

 

[Jorden Verwer]

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.

The 1/f noise ends up in a part of the spectrum that you were going to
filter out anyway, given that you're using a chopper amp.

It is not offset, though the chopper amplifiers can mask it out.

No, it's not the same, but it is related. It has many of the same
properties.

 

[Eeyore]

Phil,

You have a mental illness. You probably don't realize it, but it's obvious
to others. If you're not already doing so, for your own sake, you should
seek professional help.

I agree with you but of course now he'll call you a lunatic too !

Graham

 

[Eeyore]

So what. Anyone who participates in the newsgroups has a mental
disorder. Normal people have no interest for that; they have sex, pray
God, take precarious mortgages and watch TV. This is what they call
"having a life".

Doesn't sound like much of a life to me except the sex bit.

Graham

 

[Eeyore]

OK, but was it representative or just broken?

Brand new out of the box as I recall. It met its miserable specs. It
sounded like a gravel machine.

Why are so against low distortion ? You're sounding like a tubie.

Graham

 

[Eeyore]

By using well-trained, well-chosen listeners.

Chosen by whom ?

Graham

 

[Eeyore]

I don't think you really understand what proof or good experimental design
and analysis is, Graham.

I don't think you understand that ultra low distortion is a GOOD THING.

You're merely an apologist for the mediocre.

Graham

 

[Eeyore]

"Eeyore" wrote

And as I said, all the audiophool golden ears say *exactly* the same
thing.

But I don't claim to be an "audiophool golden ear", just someone with decent
hearing.

Graham

 

[Eeyore]

Better than a Prism Sound ADA-8

Which isn't test equipment anyway.

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.

Graham

 

[Jorden Verwer]

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.

 

[Jorden Verwer]

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.

 

[Phil Allison]

"BobWanker"


** Drop dead you fucking tenth witted ass.




...... Phil

 

[Eeyore]

"Eeyore" wrote


The specs are such that the machine could have a pretty serious fault, and
still meet specs.


Me, against low distortion?

However, there's plenty of evidence that THD below 0.02% in actual use is a
nit.


Not at all.

0.02% is at least more reasonable than 0.1% which is all even some modern
transistor amps can deliver.

I'm happier with 0.01% myself (that's why I designed for 0.008% on my 700D
model) although as I've stated before, full power THD is only a small part of
the whole story.

Graham

 

[Eeyore]

"Eeyore" wrote


Again, that is exactly we hear from virtually all of the audiophiles who
believe in weird cables and all the rest.

There is a pervasive natural tendency to underestimate the effects of bias
on what we perceive. Most people are shocked by what they hear the first
time they participate in a bias-controlled listening test involving even
subtle, but audible differences. They find out that they have been living in
a glass house.

Well, you're wrong about this one. Remember it was a comparison between a 0.1%
rated THD amp and one with 0.01%. You yourself have set a benchmark in your
previous post of 0.02%.

Graham

 

[Eeyore]

"Eeyore" wrote

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.



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 ?

Graham

 

[Kevin Aylward]

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
[email protected]
www.kevinaylward.co.uk

 

[Kevin Aylward]

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

 

[GregS]

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

 

[Mr.T]

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.