Mu-Tron made this unit in the late 1970s, consisting of a large metal box and separate wah-style foot pedal. It has two sweep generators & 2 phasers that can be used individually, together at the same time or, they can interact with each other. It was used heavily on Siamese Dream. In Vieuphoria, Butch Vig says of the device: "This is one of the secrets to our secret sound. This is the Mutron Bi-Phase. We run everything through it- everything. It's fabulous."
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