Yamaha PS-400 PortaSound Retro FM Synthesizer (Matching Hardcase)Yamaha PS 400 An innovative little instrument for 1982, the Yamaha PS 400's sound generation is by Yamaha's Pulse Analogue Synthesis System, P. A. S. S., first used on the large home organs such as the C and D Series. This little keyboard packs a great lo fi punch and looks incredible in it's rare dark red chassis. The PS 400 features a Transposer, a Chord Sequence memory, and a Duet function, which automatically harmonises each note played according