ARP Quadra

The ARP Quadra was a 61-key analog synthesizer produced by ARP Instruments, Inc. from 1978 to 1981. After the costly failure of their Centaur poly synth design and poor sales of the Avatar, they desperately needed some sort of poly synth but had neither the time or resources to develop a new product. The result was the Quadra, a paraphonic synth based on pre-existing products: the Omni string/organ/bass synth, a basic mono synth similar to the Solus, a phaser and a VCF, in one box.

It has four sections. Bass is on the bottom two octaves, has two unison bass circuits (electric and string), 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 Solus and a five way mixer with four unit outputs, a stereo pair, a line mono and an XLR out.