A device that accepts MIDI messages and produces control voltages based on the received MIDI messages. Such a device is intended to allow MIDI control of older analog synthesizers which do not have MIDI interfaces, or to control a modular synthesizer. The most basic type of MIDI-CV converter will accept MIDI note on and note off messages, and produce two outputs: a control voltage which is proportional to the MIDI note number contained in the note on message, and a gate signal which is toggled by the note on and note off messages. More sophisticated devices will process pitch wheel and portamento messages and use these to influence the control voltage, and will produce additional control voltages derived from the note-on velocity, aftertouch, and continuous controller messages.