Pulse Dividers -- Good for polyphony??

[gstopp at fibermux.com]

     Digital dividers for subharmonics are pretty cool, especially for the 
     miniscule amount of complexity that they involve. The sub-octave stuff 
     on the Micro/MultiMoogs are a little boring. Once you throw in some 
     three's and six's however things get better. If you run a VCO into a 
     2-3-4-5-6-8-10 divider with a mix pot on each division, you can easily 
     get a "bunch of oscillators" sound that is surprisingly fat 
     considering everything is phase-locked. It would probably be a cool 
     thing to have two divider chains driven by two VCOs, slightly detuned 
     from each other.
     
     Unfortunately the only waveform that lends itself to division is a 
     square. You can approximate a sawtooth with summed divider outputs but 
     your driving oscillator must be much higher in frequency than the 
     result. For example, if you want a 64-step staircase sawtooth you need 
     6 bits, so you need to sum the divide-by 2, 4, 8, 16, 32, and 64 
     outputs of a divider chain and so your slightly quantized-looking 
     sawtooth output will be 1/64th the frequency of your VCO.
     
     Speaking of dividers there's a circuit in some old Electronotes called 
     a "Convolver" that has two divider chains driven by two seperate VCOs, 
     and the corresponding outputs from each chain are AND'ed together and 
     all the AND gate outputs go to a mixer. According to the text, this 
     thing sounds "so thick you can cut it with a knife" and "seems to 
     sound in tune" even if the VCOs are detuned by a large amount. Maybe 
     I'll build one some day...
     
     - Gene
     gstopp at fibermux.com


______________________________ Reply Separator _________________________________
Subject: Pulse Dividers -- Good for polyphony??
Author:  MACHINE MEDIA <cdmaster at netcom.com> at ccrelayout
Date:    5/20/96 2:29 PM


There was a brief thread on pulse dividers (for sequencer clocks) on another 
list which got me thinking.  Most of the old tube organs (I'm referring to 
keyboard instruments :) used pulse dividers.
     
Would using TTL/CMOS pulse dividers be a good way to add polyphony to a 
modular synth??  Would taking the square wave output and dividing 
it by 3, 5, etc. to produce the other notes in a chord a workable idea?? I've 
looked at alot of synth circuits and many of them use a couple of flip-flops 
to produce an output one octave below the VCO. I was thinking that a group of 
"divide by N" counters (like a 4018) would be more flexible than having fixed 
divisions. 
     
Is there a way of dividing down sawtooth or other waveforms besides a 
square??
     
Any thoughts?? Has anyone ever tried anything like this??
     
PEACE OUT :)
MARK