The Audio Design Recording (ADR) Compex F760X-RS is a 2U stereo dynamics processor with compression, limiting, and expansion/gating. Electronics are all discrete, and the gain reduction element is a single FET which takes control signal from the compressor, limiter, and expander simultaneously. Input and output gain are set with stereo controls.

This box was widely used in the 1970s, most notably on the drums for Led Zeppelin's "When The Levee Breaks"