Phase 90

Phaser

The 1974 original four-stage phaser. Van Halen "Eruption" in a small orange box.

The Phase 90 was MXR's debut pedal in 1974, establishing the company and creating one of the most recognized effects in rock history. The "90" references the 90-degree phase shift in its four-stage circuit, creating two notches that sweep through the frequency spectrum.

Eddie Van Halen put this pedal on the map, using it on "Eruption," "Ain't Talkin' 'Bout Love," "Atomic Punk," and throughout Van Halen's first album. The distinctive swooshing became synonymous with late-70s rock guitar.

Script Logo versions (1974-1977) used a single UA741CP op-amp and are considered warmer and more subtle. Block Logo versions (1977 onward) switched to TL062 dual op-amps with a brighter, more pronounced sweep. The circuit uses 2N5952 FETs as voltage-controlled resistors.

MXR went bankrupt in 1984; Dunlop acquired the brand in 1987 and continues production. The single-knob design keeps operation simple: just set the speed and play.

Used By

Eddie Van Halen — Used original bright orange box MXR Phase 90 with script logo on 'Eruption' and 'Ain't Talkin' 'Bout Love'

Joe Satriani — Added EVH-spec MXR Phase 90 to pedalboard for Best of All Worlds Tour (2024) to authentically recreate Van Halen tones

Steve Vai — Used on Passion and Warfare album (1990) - iconic phaser for songs like 'Liberty' and 'For the Love of God'

Demo Videos

Specifications

Power9V DC

Current Draw25mA

Polaritycenter-negative

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MXR

Phase 90

Phaser

The 1974 original four-stage phaser. Van Halen "Eruption" in a small orange box.

MXR went bankrupt in 1984; Dunlop acquired the brand in 1987 and continues production. The single-knob design keeps operation simple: just set the speed and play.