The Yamaha MU-series is a line of sound modules built by Yamaha. All sound modules except MU5 support Yamaha XG. The sound modules were commonly used when computers had slower processors. The computer could send MIDI commands to the sound module, acting as an external sound generation device. Later MU sound modules feature A/D inputs that allow direct input from microphones and guitars.

Yamaha XG is an extension to the General MIDI standard, created by Yamaha. It is similar in purpose to the Roland GS standard.