VCA salvaged from old stereo?

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DJ_JITTER
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VCA salvaged from old stereo?

Post by DJ_JITTER » Sun Sep 09, 2018 11:27 am

I've got an old 2.1 PC speaker setup that I've lost the cables for, so I've opened the sub/amp up to see if there's anything worthwhile I can do with it. There's a couple of 2-channel VCA ICs on the board that I think might be able mod into a VCA for eurorack. It's this older chip.

I don't particularly want it to be a good quality VCA for audio use, just something to add a bit of modulation to CV signals. I've been looking at some other VCA schematics, but does anyone know of any super simple circuits I can base it off?

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appliancide
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Post by appliancide » Sun Sep 09, 2018 5:13 pm

I don’t think a simple eurorack vca is going to be possible with that vca. You would need a compander since it can only deal with a maximum of around 5v. Could be a fun circuit to build into an external enclosure.

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Post by guest » Sun Sep 09, 2018 11:25 pm

i like that it can do 2 independent VCAs or a balance control. the CV inputs are 0V to 5V, so thats nice, but the audio inputs would need to be capacitively coupled both in and out as the circuit is bipolar. a simple attenuator at the input and amplifier at the output should work for dealing with its lower input voltage requirements.
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