[sdiy] Multiplier vs VCA?

[Steve Ridley]

> It is possible to "bend" the control response of the dB/V VCA 
> chips to implement linear response VCA's.........
>
> Anyone know if this circuit technique is being used in any currently 
> available synthesizer modules? (it is being used by Modcan)

This is an elegant approach made possible by having four
expo VCAs on the one IC.  I think every example of it I've
seen credits you.

However, more basic approaches to getting a linear
response VCA using an expo response VCA and a
log converter in the CV circuit go back a long way in
the pro audio industry.  Proper log converters and 
diode network appoximations can be found in many
high quality mixing desks.  These approaches are
not always temperature compensated, but the ear is
less sensitive to level than to frequency.  I think Serge
did some discrete versions of this sort of stuff in the
late 70s - nothing's new in analogue synths... 


Steve