Polyfusion Sound-A-Round Quad Panner

via this auction
"This vintage Polyfusion quad panner, model QP-1, is very rare- there were only a couple of hundred ever made. It is the Holy Grail for Polyfusion modular synth owners , but would also be of interest to anyone who owns a recording studio or quad P.A. system. It features a joystick with amazing real time control, which allows you to move the sound from any quadrant to any other quadrant instantly, reverse direction, etc. There is also an auto and manual mode, which lets you do this either way. It was made famous by Pink Floyd, who still use it in their live show- it is what they use to move the sound around so convincingly on their quad system."