Ruud Broens wrote:
"John Woodgate" wrote in message
...
I read in sci.electronics.design that Kevin Aylward
kevindotaylwardEXTR wrote (in
.net) about 'A little
feedback worse than none at all?', on Wed, 19 Nov 2003:
Err.. John and me are arguable, friends. My comment was not at him
personally, but at what he said. What he said was crap.

No, Kevin, it isn't. What happens when you apply lots of feedback
around an amplifier of poor linearity is that you swap maybe 5% of
low-order distortion (2nd, 3rd, 5th.) for 0.05% or so of every
harmonic up to the upper band limit of the amplifier. The latter
sounds FAR worse, because of the multiplicity of intermodulation
products, some of which are much larger in amplitude than the
adjacent harmonics. --
Regards, John Woodgate, OOO - Own Opinions Only.
http://www.jmwa.demon.co.uk Interested in professional sound
reinforcement and distribution? Then go to http://www.isce.org.uk
PLEASE do NOT copy news posts to me by E-MAIL!

Here is one problem of the concept of feedback itself:
it is all very well to model perceived physical phenomena
in a suitable mathematical form, convenient to 'get rid of'
time by using complex numbers, but

a cause-effect-feedback chain of events does not occur in zero time,
whatever your modeling might lead you to believe.

Ho hummm. The model includes time. Explicity. Its a non issue.

The transfer function of:

Vo(jw) = A(jw)/(1 + A(jw).B(jw))

Includes time via the phase of A(jw) and B(jw))

In the laplace domain

Vo(s) = A(s)/(1 + A(s).B(s))

Incluses time in its inverse.

So here is one, just for Kevin:
what are you actually correcting there with a feedback signal ?


Its all in the wash. The math accounts for any and all time delays. One
just crunches the numbers.


Kevin Aylward

http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
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Understanding, is itself an emotion, i.e. a feeling.
Emotions or feelings can only be "understood" by
consciousness. "Understanding" consciousness can
therefore only be understood by consciousness itself,
therefore the "hard problem" of consciousness, is
intrinsically unsolvable.

Physics is proven incomplete, that is, no
understanding of the parts of a system can
explain all aspects of the whole of such system.