[sdiy] 1v/oct expo converter front end for SSM2164 quad pole vcf..

[Neil Johnson]

Hi,

Jean-Pierre Desrochers wrote:
> I had not seen the expo voltage to current response
> embedded for all the CV pins stated in the datasheet..
> I'll have a look again in the specs.

The SSM2164 control response is -33mV/dB.  dB is an exponential scale. 
A doubling of voltage is 6dB, so that means the 2164 is about -200mV/octave.

For something like a VCO you'll also want to compensate it as the 
control response has a large temperature coefficient.  That's what the 
schematic that you referred to is doing - the first 2164 gain cell is 
proving temperature compensation of the CV for the second gain cell, 
which is providing the current into the saw integrator.

Cheers,
Neil
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