Available as an assembled Module and as a DIY project.
No info about availability.
The Warp633 is a Ring Modulator / Warper based on the 4 quadrant multiplier chip AD633 made by Analog Devices.
http://m.bareille.free.fr/modular1/warp633/warp633.htm
Included in 4 Racks, 4 are public:
