resonance VCA in Memorymoog ?

[Joachim Verghese]

On Thu, 28 Nov 1996, Haible_Juergen#Tel2743 wrote:

> How is the resonance control implemented?

This is from memory:

The signal on the emitters of the top transistors in the ladder
are buffered by JFET op-amps (1st stage of an instrumentation
amplifier).
The differential signal is then routed to the main VCA (CA3080),
and also to the resonance VCA (CA3080). The signal which enters
the resonance VCA is attenuated so that overdrive only occurs at
the VCA input.

Now comes the bit which I don't remember clearly - how is the
resonance VCA controlled? I seem to recall that it's the normal
V-to-I converter using a PNP transistor, yielding virtually
linear control.

Since the main CV DAC is a 12-bit device (6012), they probably
implemented a non-linear resonance taper in software.

-joachim