The GR-33 has a sound set based on the Roland JV-1080 synthesizer. Unlike the JV series, it does not support expansion with a plugin board. It is meant to be used with a guitar that has a Roland GK-2A pickup or equivalent and will also work with the GK-3 or a Yamaha G1D pickup.
It sounds very similar to its predecessor, the GR-30, but has an improved interface and a controller pedal. A stripped-down version was released as the Roland GR-20. It was followed by the GR-55.