http://www.sara.nl/Rick.Jansen/Emusic/Synth-diy/Archive/286

[chris crosskey]

I'm new to this site, but I've been building up a DIY modular 
around mostly Elektor Formant stuff (I managed to find some 
726's after about 3 months of trying. I was going through 
your archive, and see that someone is/was planning to build a 
whole bunch of VCO's just to have the stacked sawtooth 
effect. It isn't neccessary as one of the Digisound kits from 
the eighties (Published in ETi) was a unit that from one 
sawtooth in gave six extra sawtooth out all mixed into a 
single output. It constantly phase-shifts all six extra 
waveforms in order to create the effect of sixfractionally 
detuned oscillators. The design could easily be modified to 
provide only four extra waves, or you could build multiple 
modules for more. There are no hard to find bits, it's all 
normal op-amps etc. I haven't built mine yet (I know someone 
who has), as it'll need some mod with a pre-amp to work with 
my Formant stuff.
                    Chris Crosskey