The GS-500 guitar and GR-500 synth engine were designed as the world's first true guitar synthesizer. More astonishing than its original release date of 1977 is the fact that this early guitar synth predates MIDI, functioning instead using an implementation of the CV and GATE signals common to modular synthesis. Another incredible feature was the built-in infinite sustainer system, utilizing grounded frets and a customized humbucker for incredible sustained notes and chords across all 6 strings.

A New Kind of Hybrid
The GS and GR-500 represented a completely new kind of hybrid instrument, fusing the sounds of guitar and synthesizer and allowing them to be controlled at the same time. Expensive and somewhat of a novelty at the time, we've grown quite partial to the feel of this combo. The innovative features, incredible playability, and natural responsiveness have transformed into a powerful, flexible, and fun library capable of everything from big fuzz guitar tones to sweet synth pads, and more.

https://www.uvi.net/px-guitar-syn