Jitter in VCOs

[jean-charles maillet]

I've been wondering lately what kinds of circuits may generate which kinds
of sounds in a synthesizer, etc ... I've noticed that several synth
enthusiasts believe in "best" technology for implementing their gear ... I
wonder if that's not a mistake ?!

I've been pooring over the VCS3 schematics for a few weeks and I suspect
that the VCOs there are capable of considerable jitter since the
single-ended switches and reference levels will drift dynamically in time
(this is a universal properties of all VCOs).  In other words the spectrum
sidebands would be fatter for such an oscillator, how much flatter would
depend on jitter amplitudes and frequencies.

As in vacuum tube circuits where 5% of 2nd harmonic distortion/enhancement
contributes good richness to a solo source like a harp or guitar (maybe not
full mix) then perhaps 5% jiiter on an oscillator (discrete Moog, EMS, ...)
might sound more pleasing than the 0.01% jitter of an op-amp based VCO.
Has anyone done a comparative test of VCO architectures with a spectrum
analyser ?!

Lot's of people think that a square wave is a aquare wave, regardless of
whether it's been generated with op-amps or discrete transistor circuits
... I got a funny suspicion just by looking at the circuits of the VCS3 and
others that this just ain't so, there's more ... I wonder if that's the
"cheapness that makes great monster movies and fat mini-sounds ?!

jc

  "The only two good things America gave the world are Coke and Slimmy"

                                                               Frank Zappa