Until recently, it never occurred to me to use a ring modulator as a VCA. I typically have sizable systems with dedicated VCAs. But if I think about it, why wouldn’t it work? A ring modulator multiplies the X input signal by the Y or carrier signal. Essentially, this is how a VCA works, but the ring mod does not have a CV or gain control. Those with a small system already know this trick and save themselves space in their rack.
But what about a vacuum tube ring modulator? It’s a very different design than a solid state ring mod, even though they both perform a multiplication of the X and Y signals. The module uses tubes and transformers in a 1930s circuit design originally purposed for sending multiple telephone calls down one telephone line.