The 285t Frequency Shifter is an interesting module for processing audio samples or live voice input via a microphone through the 207t Mixer/Preamplifier module. The "sum" and "difference" outputs from the 285t can then be routed to the 292t Quad Lopass Gate, creating dynamic tone shaping. By further splitting the processed signals into the left and right channels, this setup allows for a rich stereophonic effect.

The theory of shifting frequencies using analog multipliers was first invented in the early 1900s. However, in 1971, Don Buchla took this concept and explored how it could interact with the audio signals of his modular synthesizer. By combining it with a balanced modulator into a single module, he likely created one of the world's first analog audio effect processor modules.