The ARP Quadra was a 61-key analog synthesizer produced by ARP Instruments, Inc. from 1978 to 1981. The machine combined pre-existing products: the Omni, Odyssey, a Solina-esque string synthesizer unit, a phaser and a divide-down organ with ADSR envelope, and a 4075 24 db low pass filter into one box. It has four sections. Bass is on the bottom two octaves, has two unison bass circuits, with AR and a single pole low pass filter and a related AD envelope for cutoff. A string section is similar to the ARP Omni. Poly Synth, and a two voice Lead Synth similar to the Odyssey and a five way mixer with four unit outputs, a stereo pair, a line mono and an XLR out.

ARP Instruments, Inc. was a Lexington, Massachusetts manufacturer of electronic musical instruments, founded by Alan Robert Pearlman in 1969. It created a popular and commercially successful range of synthesizers throughout the 1970s before declaring bankruptcy in 1981. The company earned a reputation for producing excellent sounding, innovative instruments and was granted several patents for the technology it developed.