The instrument
When the MS-10, MS-20 and MS-50 synthesizers came onto the market, function-specific modules were introduced to make it easier to connect the different models. These modules offered additional functions for live performances and studio applications. With the MS-01 Foot Controller, a voltage signal could be regulated to control individual synth modules. CV/gate signals could be converted with the practical MS-02 interface. With the MS-03 signal processor, you could convert audio signals into CV/gate signals and in this way connect a synth to external instruments. The internal LFO of the MS-04 modulation pedal could be used to control the VCO and VCF of an MS series model.
Details
The MS-03 interface takes a monophonic audio signal and converts it into a control voltage (either Hz/V or octave/V) and also generates triggers and an envelope from the audio signal. Essentially, it allows the user to control the frequency of a synthesizer's oscillators, trigger its envelope generators and contour a parameter (e.g. filter cutoff) from an instrument or microphone. The MS-03's circuitry is similar to the pitch-to-voltage circuitry of the Korg MS-20, but is faster and more accurate. It can control almost any monophonic analog synthesizer.