[sdiy] Quick query about 2164 VCAs

David G Dixon dixon at mail.ubc.ca
Sat Mar 16 19:42:29 CET 2019

Quick answer, without giving it too much deep thought:  I don't see why not.

As long as you terminate all of the 2164s to a virtual then you should be
golden.  Just be cognizant of how much current you are summing and putting
through a single 2164 in the chain... you don't want to run it into

If you are using two 2164 VCAs for things such as wet/dry balance, you might
want to consider using a single-2164 crossfader instead.  If you want really
accurate crossfading, it requires a trim, but it does save an entire
linearized VCA circuit.  I can hook you up with a schematic if you're

-----Original Message-----
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Tom
Sent: Saturday, March 16, 2019 11:15 AM
Subject: [sdiy] Quick query about 2164 VCAs

Hi all,

I know you can mix together the outputs of several 2164 VCAs direct into the
input of another one, but can you mix together the outputs of several VCAs
into the inputs of several VCAs simultaneously?

The situation I've got is this: I have a wet and dry level controlled by a
VCA each. These are brought back together at a single point (which will need
to be a virtual ground node). I then have Main and Phones outputs, both
controlled by a VCA each too. Can I connect the inputs of the two output
VCAs together and mix the outputs of both the Wet and Dry VCAs into that
same single point? Will the current divide equally between the two output
VCAs? Will I need to adjust the output I-to-V stage resistors to compensate
for the fact that each VCA only gets half the current?

I love the fact that often with the 2164 VCA you can omit the following
I-to-V stage and just feed the current direct into the next stage somewhere.
There's often no need to go back to a voltage before turning things into
currents again. I'm hoping that's the case here too! ;)


       Electric Druid
Synth & Stompbox DIY

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