The Yamaha DX9 is a spin off synthesizer of the family of the DX7 built by Yamaha.
It uses FM synthesis[6] and has 16 note polyphony; however, it only has four FM operators for sound generation compared with six on the DX7 (without alternative firmware ROM).
[7] It is the least complex of the DX range of synthesizers and has only 20 on board memory locations.
[8] The DX9 contains 20 pre-programmed voices which include: brass, string sounds, piano, organ and synth sounds.
[9] User created voices (sounds) can be saved on cassette tape for later use.