Compex

Throughout the 1960s, '70s and '80s British manufacturers Audio & Design (Recording), now called Audio & Design Reading, enjoyed a phenomenal reputation for class-leading audio signal processors. Their now-classic F760X RS 'Compex' dates from the very late '60s. It was an elaborate and incredibly versatile compressor-limiter-expander, which employed discrete transistor electronics, with a single FET gain-reduction device in a form that ADR called a 'vari-loss amplifier'. FET-based compressors were popular back then, but what made the F760X unique was the way in which this FET was driven simultaneously by the combined control signals from three separate side-chains (limiter, compressor and expander).