The ring modulator (often abbreviated “ring mod”) is a powerful circuit for transforming sound and yet is one of the easiest to build, if not understand. It plays a vital role in the basic kit of old-school 1950s electronic music, but it’s even older than that. The ring modulator is part of a larger family of “double-balanced amplitude modulators” that goes back to electronics year zero. The catchy term “ring modulator” refers to the daisy chain of diodes at its core. In the 1950s electronic music adopted the ring mod, along with other bits of radio gear, to perform tasks for which they were never intended. As technology evolved, more complicated circuits performing the same function were developed, with names like “analog multiplier,” but the original ring modulator uses just four diodes and a pair of audio transformers. The ring mod’s simple arithmetic turns input sounds inside out and creates new ones.