Just a thought, The PSIM can also serve as a quantizer for non 1V per octave VCOs. For example the Buchla 258s have roughly a 2.5 volt per octave responce. So the 10 volt output of the PSIM would cover 4 octaves. 2.5 / 12 = 0.208 millivolts per semitone. That translates to 80 DAC counts per semitone instead of 32. To make a chromatic quantizer for a Buchla 258 the equation is DAC1V = (MIDINOTE-MIDIOFFSET)*80 Use the coarse and fine scale controls on the 258 for precise tuning. For EML synths with a 1.2 volt per octave scale, one semitone = 100 milivolts. For EML synths use DAC1V = (MIDINOTE-MIDIOFFSET)*38 the actual number is 38.5 so for EML some tweeking of the DAC voltage reference may be needed for perfect tune. I don't recall the EMS Putney and Synthi numbers, they are less than 1 volt per octave, but the same technique applies. Just adjust the number of DAC steps to match the target synths volts per semitone number.
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Quantizer for non 1V octave VCOs
2004-02-24 by grantrichter2001