It is called a gimmick capacitor, used to get a very small pico-farad capacitance and it is here in place
of a proper compensation capacitor on the op amp. It seems to let one be able to 'tune' the noise
easily, this is available to tweak in VSDSX as the
HPF
knob. It lets you filter out some of the noise
generator frequencies and is nice to produce a fuller noise sound, the SNARE in VSDSX have an extra
setting called
FULL NOISE
which will brings all of the noise generator frequencies.
THE SSM2044 VCF
The iconic
Curtis chip SSM2044 (but also low cost) low pass filter
was used to filter the noise in the
SDS-V, the resonance can be tweaked but never in a big amount and you will not reach self-
oscillation on the SDS-V. This is the type of filter that will not maintain the gain around the cutoff
resonance, so you will lose the bottom end. The frequency CV of the filter will be affected by the
envelope and the trigger velocity, the noise will get duller as the sound decay. The snare is connected
differently and the envelope will not affect the frequency CV (which is more like a real snare).
THE VCO
