The RS-09 is an analog string and organ synthesizer (similar to the Saturn-09 which only produced an organ sound). It's old, it's cheap and they're usually worth finding! The string sound and organ sounds are nice, fatty analog sounds. The organ and string sections can be played simultaneously or individually. An ensemble/chorus effect and external sound input are welcome features. But aside from all this, there isn't much else left to this synth. A simple 2-vco architecture with simple and limited editable parameters, no patch memory and a small keyboard.
There are three versions of this unit. The one shown above is a V.3. The differences are mainly cosmetic and in the control surface; the V.3 uses touch-switches, the V.1 uses rockers and tends to be more reliable due to that. This instrument can be found for around $100, and they could add a nice flavor to any modern analog-electronic keyboard studio. It has been used by Jimi Tenor, UB40, and The Cure.
Demos & Media
Images from Perfect Circuit Audio.
Additional information provided by DAC Crowell.