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This is the first Compression/Sustainer pedal released from Boss. It builds on the lagacy of the Roland AS-1. Like all compression pedals it reduces the output of sounds over a set threshold relative to the strength of the input signal, making levels consistent and improving sustain. In the CS-1 this is done by means of photocouplers. The later CS-2 and CS-3 used VCA’s (Voltage Controlled Amplifier) to create the same effect. The sound of the CS-1 is thus very different from its successors.

Boss CS-1 Compression Sustainer


  • Controls: Level, Sustain, 2 Way Mode Switch
  • Connectors: Input, Output, AC Adaptor
  • Current Draw: 5 mA (DC 9V)
  • Recommended AC Adaptor: ACA Series


  • Black – Made In Japan

The CS-1 was sold from July 1978 to February 1982.