It’s Ohm’s law, so shouldn’t come as a surprise
Yeah I know. Ohm’s law appears in so many shapes and forms everywhere that sometimes it is a surprise. I just wasn’t aware of how you would build an I-to-V converter using a resistor and a buffer, but it seems super obvious now.
In synths I think it’s usual for a VCA to have unity gain at maximum, by the way. Oscillators are already 10 Vpp after all!
I didn’t know that. I do not own a single synth and I’m trying to design modules now so knowing things like this is definitely helpful for the end-product to make sense. I just didn’t want a VCA that would have a gain <1 if you turn it all the way up so I rather have 1.1 as a maximum or something like that.
it and the pot form a pair of voltage dividers to bring the input signal down below 60 mV.
Thanks. Makes sense! 
The amplitude I was feeding into it was pretty hot though and it seems to work now, so I think I’m ready to commit this one to protoboard
Thanks guys! 