High Quality Content by WIKIPEDIA articles! The Yamaha GX-1, along with its predecessor, the Electone GX-707, is an analog polyphonic synthesizer developed by Yamaha as a test bed for later consumer synths. THe GX-1 has four synthesizer "ranks" or manuals, called Solo, Upper, Lower and Pedal, plus an analog rhythm machine. THe Solo rank features a 3-octave, 37-key keyboard with full-width, but shorter than normal keys. DIrectly above the Solo keyboard runs the Portamento keyboard - a ribbon controller which can be used to play continuously variable pitches roughly corresponding to the Solo keyboard note below. THe Portamento keyboard over-rides the solo keyboard if used simultaneously. THe Solo rank has only a single oscillator, but has a dedicated LFO, pitch envelope generator and ring-modulator. THe Upper and Lower ranks each have a full-sized 5-octave, 61-note keyboard. THey are both 8-voice polyphonic, with two oscillators per voice. EAch poly rank has a dedicated LFO, and there is a common "random" modulation generator. THe Upper rank also has horizontal aftertouch which can be assigned to pitch, volume or filter, and a polyphonic glide function.