[sdiy] Request brain dump on balanced lines

[Grant Richter]

Hi Don,

>> You can see, or even listen to the error, just by monitoring the
>> differential between the inverting and non-inverting
>> terminals. (difference = servo failure).
> 
> Yes.
> 
> But still, for there to be an output there will be an error voltage.
> 
> One can claim that the error is negligible or that the error doesn't
> sound bad, fine; we're talking subtleties, certainly.
> 

I'm not disagreeing with your remarks. Just wanted to add a "Kids, try this
at home" element for DIY.

As much as op-amps fail for pristine audio playback, they certainly work
well for generating signals.

Shannon's original model for a noisy channel assumes an encoder, channel
with noise and a decoder. It seems to me the model fails in the case of a
music synthesizer, which is an encoder operating in a closed loop with a
human operator.

In that sense, because synthesis is parametric, the operator adjusts other
parameters to compensate for imperfections in the encoder itself. For
example, distortion produces more harmonics which can be compensated by
changing the filter parameters, returning to the harmonic balance the
operator desires.