MXR Phase 90

The MXR Phase 90 by Dunlop is a phaser guitar pedal that has been a staple on pedal boards for over four decades. It offers a warm modulation that can be adjusted from subtle, spatial shimmer to high-velocity swooshing with a simple twist of the Rate knob. The pedal can be powered by a 9-volt battery, a Dunlop ECB003 9-volt adapter, or the DC Brick™, Iso-Brick™, and Mini Iso-Brick™ power supplies (not included).

The Phase 90 circuit is designed around a Phase Shifting Stage with an Input Buffer to avoid tone sucking. The last Output Mixer Stage combines the wet and dry signal to create the phase effect. The modulation is controlled by a single knob that sets the speed of the effect, which is generated by a Low- Frequency Oscillator (LFO) that produces a triangular sub-audio waveform.

The Phase 90 features a feedback resistor labeled R28 that makes the effect stronger and more pronounced, causing a boost and even distortion in the midrange. The pedal's design includes a power supply stage, input buffer stage, phase shifting stage, LFO, and output mixer stage.

The MXR Phase 90 is available for purchase at a price of $99.99 USD.