[sdiy] Multiplier vs VCA?

[Tim Parkhurst]

> -----Original Message-----
> From: jays at aracnet.com [mailto:jays at aracnet.com]
> Sent: Friday, August 20, 2004 10:58 AM
> To: Steve Ridley; synth-diy at dropmix.xs4all.nl
> Subject: Re: Re: [sdiy] Multiplier vs VCA?
> 
> I think there are 2 main reasons.
> 1) Availablity and cost. Having to order a tube of something at $4-$5 a
pop from
> the manufacture.
> 2) If I remember right these have a log response to control voltages.
> a) Most of our VCAs have linear responses because our envelope generators
have a
> log curve.
> b) Have to get really creative to use these in VCOs with a exponental freq
> response.
> c) Only place I can think of a log device being useful is for a pan/morph
circuit.
> 
> 

Okay, so we hang a lin -> log circuit (i.e. expo converter) on the front end
of linear VCOs all the time to give them a log response...

So how difficult is it so hang a log -> lin circuit (antilog?) on the front
of an expo VCA to give it a linear respose? I've seen the trick mentioned by
Mike Irwin. Does this give you a VCA with expo and linear outputs? Is there
a simpler log -> lin circuit? Does this sort of circuit suffer the same
temperature dependency as the familiar expo converter? How many angels can
dance on the head of a pin? Why is the sky blue? Where do babies come from? 

Sorry, got carried away there, but the first few questions still need
answers (I've figured out the last two).


Tim (is a log jam the opposite of a lin jam?) Servo

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