As the standard is incorrectly set for MSX audio output, the balance between the built-in sound source and the external sound source varies from model to other. This expansion is equipped with a OPLL chip YM2423 and a PSG YMZ294 as sound generators to solve this problem by adjusting the sound volume of each from them. It also has a cartridge slot to add an external sound sources such as a Konami Sound cartridge for example.

A ROM that contains a dummy FM Bios is sold in option. Some software may fail to recognize it. It isn't necessary for MSX computers with build-in MSX-Music.

Cartridge contacts are tinned. Sold without case.

Price: ￥23,800 or ￥12,480 for the kit version.