In this Big City Music demo, the Analogue Systems RS300 CV/MIDI Eurorack module is used to take a control voltage and convert it into MIDI messages:

In this case we’re using the Analogue Systems RS35 External Processor module to convert the Moog Cherry Etherwave theremin audio into a pitch control voltage. That control voltage in turn is controlling the pitch bend of the Dave Smith Prophet ‘08 keyboard. By setting the pitch bend range on the DSI you can decide the range of the theremin’s control. The RS300 module can actually control multiple midi parameters at one time. For recording synthesists the RS300 can be an invaluable tool for recreating complicated modular patches and sequences.