MXR co-founders Terry Sherwood and Keith Barr met as high school students at Rush-Henrietta Senior High School in Rochester, New York. Together they started Audio Services, an audio repair business, where they repaired stereos and other music equipment in their rented basement apartment. This experience led them to form MXR and begin producing their first original effect pedal design, the Phase 90, quickly followed by the Distortion +, Dynacomp, and the Blue Box. Michael Laiacona joined this early MXR team in the key role of sales. Barr later left MXR and went on to found Alesis, Sherwood, and the top five managers/engineers of MXR co-founded Applied Research & Technology, and Laiacona (was long gone when inbred fighting between genius Keith Barr and others within the MXR family caused the death of MXR) and had founded Whirlwind USA.
Jim Dunlop acquired the MXR brand in 1987 and continues the traditional pedal line of original MXR classics that have come to define the brand, such as the Phase 90 and Dyna Comp, as well as modern pedals like the Carbon Copy and Fullbore Metal. Dunlop has also added a line dedicated to bass effects boxes, MXR Bass Innovations, which has recently released the Bass Octave Deluxe and Bass Envelope Filter. Both pedals won Editor Awards in Bass Player Magazine and Platinum Awards from Guitar World Magazine. The MXR Custom Shop is responsible for recreations of vintage models such as the hand-wired Phase 45, as well as doing limited runs of pedals featuring premium components and highly modified designs such as the new Custom Comp.