[sdiy] favorite "magical" opamp?

[Harry Bissell]

hmmm... I would not exactly agree in the case of tubes, whose parasitic
elements include microphonics and succeptability to vibration at certain
frequencies.  If you include 'mechanical' design as well as electrical design, that
might change the picture.

Guitar amps are an excellent example. You need to include the mechanical
environment in order to get (or avoid) certain sounds.  I've used the same
amplifier chassis both in a 'combo' and a separate 'head' and the sound is vastly
different.

Hit the frequency where the tube elements vibrate internally, and listen.
(maybe you like it, maybe you don't... but it sure is more different than just
swapping opamps)

H^) harry


----- Original Message -----
From: René Schmitz <uzs159 at uni-bonn.de>
To: David G. Dixon <dixon at interchange.ubc.ca>
Cc: synth-diy at dropmix.xs4all.nl
Sent: Thu, 07 Oct 2010 11:59:47 -0400 (EDT)
Subject: Re: [sdiy] favorite "magical" opamp?

David G. Dixon schrieb:
> This discussion has got me wondering whether the way we configure these
> opamps might not be just as (or more) important than the opamps themselves.
> I'm thinking about the value of the feedback/input resistors and the use of
> compensation caps here.

IMO same thing as with tubes. Components don't have a sound per se, only 
a circuit does. The values of external resistors/impedances vs internal 
capacitances does make a big difference for example. Try this at home 
folks: Inverting unit gain amp with an opamp. Vary R, with 10k, 100k, 
1Meg, or even 10Meg resistors. Watch it processing a squarewave signal 
and notice the differences.

Cheers,
  René

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-- 
Harry Bissell & Nora Abdullah 4eva