MXR Phase 90

[1] The original model had a simple orange enclosure with a script style MXR logo.

The Dunlop models have an LED to indicate the effect is engaged, and an optional AC power supply.

[3] Van Halen first heard Robin Trower use the pedal in the mid-1970s, and used it on songs such as "Eruption", "Atomic Punk", "Ain't Talkin' 'bout Love", "Everybody Wants Some!!

[4] The 1974 Hand Wired Phase 90 is a recreation of an original 1974 pedal using new old stock (NOS) electronic components.

The Phase 90 has an orange enclosure with a single control knob: The earliest "block" variants differ from the "script" variants in that they have a more pronounced sound (caused by the addition of a 24 kΩ feedback resistor) and the maximum speed is slightly higher (caused by the replacement of a 10 kΩ resistor in the effect's low-frequency oscillator with a 4.7 kΩ one); some later vintage units also have emphasis and de-emphasis circuits.