The MXR Phase 90 is a phaser

Phaser (effect)

A phaser is an audio signal processing technique used to filter a signal by creating a series of peaks and troughs in the frequency spectrum. The position of the peaks and troughs is typically modulated so that they vary over time, creating a sweeping effect...

 effects pedal originally designed in the 1970s by MXR

MXR

MXR, also known as MXR Innovations, was a manufacturer of guitar effects units, co-founded in 1973 by Keith Barr and Terry Sherwood . MXR was based in the United States in Rochester, New York. MXR Innovations, Inc. was incorporated in 1974...

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History

The Phase 90 was released in 1972. It was the first pedal sold by MXR and helped launch the company. The original came in a simple orange enclosure with MXR's "script" logo. In 1977 MXR changed its logo to the current "block" logo. Production ceased when MXR went bankrupt in 1984. There was a transitional period in which some phase 90’s with script logo’s had box logo circuits, and vice versa.

When Jim Dunlop bought the MXR brand, production resumed. The Dunlop production models have modern additions including an LED to indicate when the effect is engaged and the option of using a power supply instead of a battery. There are a few variants available, including the standard block logo version, a reproduction of the script logo version, and an Eddie Van Halen

Eddie Van Halen

Edward Lodewijk "Eddie" Van Halen is a Dutch-American guitarist, keyboardist, songwriter and producer, best known as the lead guitarist and co-founder of the hard rock band Van Halen, inducted into the Rock and Roll Hall of Fame...

signature model. The 1974 Hand Wired Phase 90 is a recreation of an original 1974 pedal using NOS (New Old Stock) electronic components.

Description

The Phase 90 has an orange enclosure. It has a simple control scheme consisting of only one knob.

• Speed - Controls the speed of the phasing effect.