If you've ever wished for a single-stomp byway to that classic guitar rock sound, you're going to find the MXR Phase 90 a perfect place to begin your effects chain. The characteristic electric vibrato twang of this pedal is immortalized on recordings from Eddie Van Halen. It's widely acknowledged as the originating pedal for the classic guitar phasing effect. Along with its MXR brethren, the pedal - with its original phasing circuit schematic - is manufactured today through Dunlop.
The MXR Phase 90 was invented in 1974 by Keith Barr, working out of his audio repair shop in Rochester, New York. Its iconic design, featuring a bright orange casing and bold black script, immediately evokes the feel of analog '70s rock. The MXR brand soon added other effects pedals to its supply and sold them out of cars at shows and, while popular among musicians, the company folded in 1984. Thankfully, production resumed when Jim Dunlop bought the MXR brand.
The Phase 90 is a model of simplicity. It features a single stomp-switch to activate the effect, and a knob to control the rate of the sound's oscillation. The speed knob acts as a low-frequency oscillator, so increasing the rate of the effect means that the sound's frequency range will be swept more rapidly. By moving the knob from left to right, you can turn a warm, alien wobble into a rapid-fire metal pulsing. Technically speaking, the phaser is doubling the guitar's signal and then inverting the phase of the second signal, creating a notch in the frequency band where the two signals cancel each other. This notch is then rapidly swept up and down the audible range at a rate that you control through the knob.
Check out at shootout of the script versus block Phase 90 here.
Today's MXR M-101 Phase 90 pedals are tweaked from the original. One addition is the input for an optional AC adapter, providing an alternative to a 9V battery as the sole power source - a highly appreciated modernization, as there is nothing worse than hearing your pedal's sound start warping as the battery gets low during a show. Dunlop now produces a souped-up variation of the original, called the Phase 99. It is, essentially, two Phase 90 circuits housed within a single pedal enclosure of the original model size, and featuring separate knob controls for the speed of both phasers. These two circuits can be run in series or parallel, asynchronous or synchronized, providing a bevy of additional sound-manipulation options.
So, what do you think? Are these some of the best Phase 90 pedals or what? Let us know in the comments section below!