Compensating multi-stage feedback (was: RE: all tranny vca+ )

[Magnus Danielson]

From: Martin Czech <czech at Micronas.Com>
Subject: Re: Compensating multi-stage feedback (was: RE: all tranny vca+ )
Date: Mon, 3 Jul 2000 11:41:57 +0200 (MET DST)

Martin,

> I think we have to decide between distortion and intermodulation.
> Distortion of a sine wave is pretty good audible, you don't need much
> harmonic energy, and it is easy to hear a third harmonic at -60dB
> or so. In this respect Harry is right: speakers and enclosures are
> responsible for most of the distortion. With a single sine wave it
> is not so unpleasant, because it's harmonics....
> 
> Another thing is intermodulation, this is really rough, just take two
> sines and sweep one of them through frequency. The intermodulation sounds
> so bad (or interesting) because it is not harmonically related to your
> music input most of the time, really nasty. This is very easy to spot
> in a signal, no "golden ears" needed.

Good point!

These are certainly two distinct effects of a non-linear property. The thing
is, depending on the type of non-linear property will the strength of
distorsion and intermodulation products vary alot. The products of through
zero distorsion becomes worse with respect to the signal as you decrease the
signal amplitude. The clipp distorsion comes into play only at strong signals.
Off-phase clipp distorsion may also depend on the frequency of the main signal.

We really should note all these mechanisms and have a discussions on them and
thier measure.

Cheers,
Magnus