Musitronics Mu-Tron Bi-Phase

The Musitronics Mu-Tron Bi-Phase, released in 1974, is one of the most sophisticated and iconic analog phaser pedals ever created. Designed by Aaron Newman and Mike Beigel, it was a groundbreaking dual-phaser unit that combined two independent six-stage phasers with advanced control options. Each phaser featured its own Low Frequency Oscillator (LFO), offering sine or square waveforms, and could operate independently or in sync. The Bi-Phase stood out for its versatility, dynamic range, and ability to create rich, spatial stereo effects. Despite its large size and complexity, it became a favorite among experimental musicians for its unparalleled sound-shaping capabilities.

Historical Development

Origins: Inspired by the success of simpler phasers like the MXR Phase 90, the Bi-Phase was designed to push the boundaries of modulation effects. It used photoresistor-based circuitry adapted from the Uni-Vibe but introduced features like feedback loops for enhanced tonal character.
Features: The Bi-Phase allowed users to run the two phasers in series or parallel, sync their modulation rates, or invert waveforms for unique stereo effects. An optional foot pedal enabled real-time control over sweep or rate.
Legacy: Though discontinued in the late 1970s, the Bi-Phase remains highly sought after by collectors and has inspired modern recreations like the Bi-Phase II.

Notable Players

The Smashing Pumpkins: Used extensively on their Siamese Dream album to create lush, swirling textures. Producer Butch Vig described it as "one of the secrets to our secret sound."
Larry Coryell: Featured it on his Eleventh House recordings for innovative phasing effects.
Experimental Artists: Widely adopted by musicians seeking complex modulation for guitar, keyboards, and studio processing.

Popular Settings

The Bi-Phase's flexibility allows for a wide range of effects:

Classic Stereo Phasing: Phasor A set to sine wave with moderate Rate and Depth; Phasor B synced but inverted for rich stereo movement.
Psychedelic Swirl: Both phasors set to square wave with high Feedback for dramatic, pulsating textures.
Subtle Modulation: Use a single phaser with low Depth and slow Rate for gentle movement.

Legacy

The Mu-Tron Bi-Phase is celebrated as a pinnacle of analog modulation design. Its ability to produce everything from subtle phase shifts to extreme stereo sweeps made it a favorite among adventurous musicians and producers. Though rare and expensive today, its influence persists through modern reissues and clones, ensuring its place as a legendary tool in the history of effects pedals.