In article , Steve Swift
wrote:

I wouldn't criticise adding one form of distortion to offset another
form of distortion - that's all that negative feedback loops do, and who
manages without those, these days?

I would not agree with the above as it misrepresents what negative feedback
actually does.

Negative feedback does not 'offset' "one form" of distortion with
"another". (Nor is this "all" it does. :-) )

A better description is that it compares the input with the output and
adjusts the system to reduce discrepencies. Thus it changes the effect of
any nonlinearity within the loop. It doesn't do this by using "another"
form of distortion as a comparison for "offset".

Might be more appropriate (although perhaps a rather an obscure
description) to say it uses the the same "distortion" against *itself*. Or
it essentially *subtracts* the orginal distortion from itself. No "another"
involved.

Unless, of course, you regard the input signal as being "distortion". :-)

The problem with dynagroove was that it could not do this as it was trying
to 'guess' what distortion would arise on replay and pre-apply a
'correction' without being able to sense or respond to what would actually
happen when the result was played. Made worse as the replay would vary so
much from one system to another.

Slainte,

Jim

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