[sdiy] Additive/Subtractive synthesis?

[Ishaan Dalal]

I'm making a basic one-octave polyphonic analog synth for a university final
project. My quandary is whether to use additive/subtractive synthesis. For
additive, I'd probably use a square or saw oscillator for each (one of
eight) note, which would go through it's own op-amp bandpass and then mix
into the final output. This seems the simplest on paper, since changing the
Q/center freq of a state-variable filter on the fly looks like a giant pain.
On the other hand, subtractive would certainly be more compact, allowing me
to dispense with the individual oscillator for each note. The problem is,
how would I then make a VCF for each note with discrete op-amps? [Note: The
constraints do not allow me to use any of the CEM chips, though an SSM2164
VCA, or LM13700 OTA has been approved by the instructor]. Switched cap
filters are an option, but again, they would require one oscillator per
note, chalking up to the same as additive synth.

Would appreciate your comments/suggestions....

Thanks,
Ishaan

PS: 8-bit A/D converters are allowed, however generating the waveforms from
a lookup table is not.