Electro-Harmonix Electro-Harmonix is a guitar and bass pedal company that was started in 1968 by Mike Matthews. They are best known for pedals such as the Big Muff Pi and the Memory Man. They also make guitar tubes, and have been used by artists like Jimi Hendrix, who is a famous player of the Big Muff Pi. Average User Rating 0 0 votes Please sign in to rate. Your Rating 0 Contact Phone Number: +1 (718) 937-8300 Address: Electro-Harmonix 55-01 2nd Street Long Island City, NY 11101 U.S.A. Email: email@example.com Online: History History coming soon!