
RK5 Dual Lowpass Gate
RK5 Dual Lowpass Gate Ever wondered if someone had invented the lowpass gate before Don Buchla did in 1970, what it might have been like? Especially in the 1950s when there were no “integrated circuits” or such? No one had the nerve or the hallucinatory drugs to think such a thing up. But it would have been easy. A cathode follower using the right tube, plus two linear resistive optocouplers (in those days they existed but used incandescent lamps and responded very slowly), and a few capacitors and resistors. Simple, yet it was never done. It was a miracle they had limiters in the early days; and they weren’t very “good” limiters either. Tubes limit your choices but give good sound effects along the way. IF they are applied properly. Since part of our remit is to explore an electronic-music history that didn’t actually happen, one inevitable product would have been a lowpass gate. Our version is a dual unit, dead simple Sallen-Key filter with just input, output and CV input for eac