 Analog synthesizers that have no digital component and were built prior to MIDI's development can be retrofit with kits that convert MIDI messages into analog control voltages.When a note is played on a MIDI instrument, it generates a digital MIDI message that can be used to trigger a note on another instrument.The capability for remote control allows full-sized instruments to be replaced with smaller sound modules, and allows musicians to combine instruments to achieve a fuller sound, or to create combinations of synthesized instrument sounds, such as acoustic piano and strings.