The ARP Quartet is a compact, preset/variable synthesizer with four selectable voices—polyphonic brass, string, organ and piano. While the voices alone are realistic, combination of voices simultaneously chosen do not always maintain their individuality. The new sounds which appear add greatly to the flexibility of the Quartet. Most of the circuitry in the Quartet is fairly simple. For that reason, the circuit descriptions have been kept succinct, dwelling only on areas that may prove new or confusing.