Thanks to Roland, guitars and synthesizers have had a long working relationship together. The GR-500 is a vintage guitar controlled synthesizer - before there was MIDI too! It was the first synth of this kind that Roland had ever produced, back in 1977. The synthesizer module itself was a simple analog affair with Bass, Solo Synth, and String sounds based on previous Orchestral and analog mono-synths from Roland. There are plenty of sliders to adjust the VCO, VCF, VCA, and LFO sections, but no memory to store your edits.
The synth module is controlled by a "highly modified" guitar. Notice all those knobs on the guitar pictured above. It utilized a special pickup system that connected to the synth module via Roland's own 24-pin interface and controlled it using CV/GATE signals generated by the guitar's pickup system while playing the guitar. In addition to the modified pickup, there were magnets under the face of the guitar that could increase its sustain. Performance accuracy was "iffy" but good for 1977 and pre-MIDI. As a piece of guitar-synth history, the GR-500 makes an excellent collectors item and may come in handy for the occasional growl or a strummed analog sound effect. It has been used by Tangerine Dream, Mike Rutherford of Genesis and Alex Lifeson of Rush.
Demos & Media
Images from a Roland brochure.