Guitar synth\F-CV converters

gstopp at gstopp at
Wed Feb 21 00:54:32 CET 1996

     I think Mark Smart's response to find or duplicate a GR-300 is a great 
     idea. I've just started experimenting with frequency-to-voltage 
     conversion, and I can give you the schematics I have so far, but I'm 
     sure there's a ways to go before it will operate as well as a 
     commercial unit. Of course if you're after "the thrill of the hunt", 
     the stuff I've done so far looks very promising. I'm using an 
     exponential VCO in a phase-locked loop, which generates a pitch CV 
     that is already scaled to 1 octave per volt. For a guitar, you would 
     need six of these things so it might be a lot of work.
     And then there's the trickey part - deriving a clean frequency from a 
     guitar string's pitch. I would imaging that all kinds of adaptive 
     filtering, compression, peak/trough detection, etc. would have to be 
     used in order to get a pulse train that a dumb converter can lock 
     onto. Can't help ya there. Some of the nasties I've heard about are 
     the initial fall in pitch and the predominant second harmonic.
     - Gene
     gstopp at

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Subject: Guitar synth\F-CV converters
Author:  NegatvNein at at ccrelayout
Date:    2/20/96 12:45 PM

I am a guitarist and not a keyboardist and would prefer remaining a 
guitarist,not that i have anything against keyboards, but i want to build a 
guitar synth, i plan on using the GK-2a to control at least one vco per 
string (none of those silly scanning circuits) but i dont want to use midi, i 
want to build an analog interface from the gk to produce the cv for the 
vco's,i was wondering if anyone has any expierience with this or could help 
me with the frequency to cv conversion.

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