The electro-harmonix Op-Amp Big Muff Pi Distortion/Sustainer pedal brings the power to the people. The pedal relies on op-amps rather than transistors and three gain stages rather than four, to create its signature sound.According to Electro-Harmonix founder, Mike Matthews, “The Op-Amp Big Muff was popularized by the brilliant Billy Corgan who first used it on the Smashing Pumpkins’ epic 1993 album Siamese Dream. After he was videotaped playing and talking about the reissue, Billy stated: ‘The magic’s still in the box, I can still get what I’m looking for!’”The pedal relies on op-amps rather than transistors and three gain stages rather than four, to create its signature sound. It’s a sound that’s been described by noted Big Muff collector and historian, Kit Rae, as: "a huge, crushing Big Muff sound with more crunch...great for grungy, wall-of-sound distortion, heavy rhythm playing and heavy leads."The Op-Amp Big Muff Pi features standard controls: Sustain, Tone and Volume, plus a Tone switch for bypassing the tone circuit. It comes equipped with a 9V battery or can be powered by an optional 9-volt AC adapter.electro-harmonix Op-Amp Big Muff Pi Specifications:A faithful reissue of the original classic circa 1978Iconic sound and vibe that’s coveted by guitaristsControls for Tone, Sustain and Volume, plus a Tone Bypass switch.True bypass switching for maximum signal integrity in bypass modeRugged, compact, die-cast package… pedalboard friendlyShips with a 9Volt battery, also accepts an optional EHX9.6DC-200 AC AdapterDimensions (WxLxH): 2.75" x 4.5" x 2.1" (70 x 115 x 54 mm) Electro-Harmonix OP-AMP-BIG-MUFF Op-Amp Big Muff Pi Distortion/Sustainer Pedal.