Tonto's Expanding Head Band was a British-American electronic music duo established in the early 1970s by Malcolm Cecil and Bob Margouleff. The project evolved around the custom-built multitimbral polyphonic analog synthesizer, T.O.N.T.O. — featured on the band's two albums and several records by Stevie Wonder, their most notable collaborator, The Isley Brothers, and other prolific artists. Since 2013, the TONTO synth has been in the collection at the National Music Centre in Calgary, Alberta, Canada.
T.O.N.T.O.'s development began with two Moog Series III modular synths (one of which belonged to Margouleff), merged and housed in curved wooden 20×6 ft cabinets. Cecil had several technicians and engineers who helped maintain T.O.N.T.O., which had dozens of sensitive oscillators that required constant recalibration. His partners included Rex Probe, whom he met in early 1971 during a session at Electric Lady Studios in New York, and Kevin Braheny. Circa 1973–74, when T.O.N.T.O. was at the Record Plant Studio in LA, Probe introduced Cecil and Braheny to a new Serge Modular system recently launched by CalArts professor, composer, and inventor Serge Tcherepnin. Soon after, Serge and Rex designed a "New Timbral Oscillator" (NTO) module; to preserve T.O.N.T.O.'s visual consistency, NTOs had Serge Modular's iconic white panels with bright-colored connectors replaced with "faux" Moog-styled black decals. Collaboration with Serge inspired Malcolm Cecil to expand T.O.N.T.O. with modules from other manufacturers, all hidden under unified black panels: four Oberheim SEM units, two ARP 2600, and other components by EMS, Roland, Yamaha, and Blacet Research. In later years, some digital synthesizers and an array of MIDI-controlled sequencers enhanced TONTO's purely analog circuitry.
In June 1971, Cecil and Margouleff presented their debut album as "Tonto's Expanding Head Band," Zero Time, which came out on Embryo Records in the US and Atlantic/Polydor in the UK. Despite lack of commercial success, most critics praised Zero Time, with glowing reviews in Rolling Stone, Billboard, and Sounds magazines; the album gained cult status among audiophiles, industry professionals, and experimental electronica fans. Stevie Wonder, in particular, was so impressed upon hearing the Zero Time LP that he immediately invited Malcolm and Bob to collaborate. T.O.N.T.O. appeared on four of Stevie Wonder's studio albums, all crediting Margouleff and Cecil as associate producers, engineers, and programmers: Music Of My Mind and Talking Book in 1972, Innervisions (which earned Malcolm and Robert the "Best Engineered Non-Classical Recording" Grammy award), and Fulfillingness' First Finale (74). The duo worked with other high-caliber artists and bands across genres, including three albums by The Isley Brothers that featured T.O.N.T.O. — 3 + 3 (1973), Live It Up (74), and The Heat Is On (75) — and records by Gene Parsons, Steve Hillage, Billy Preston, and Weather Report. Besides T.O.N.T.O. studio sessions, Cecil and Margouleff also programmed Moog and ARP synths for various musicians and producers, such as Quincy Jones, Bobby Womack, Ravi Shankar, Stephen Stills, Dave Mason, The Doobie Brothers, and Little Feat.
In December 1974, TONTO's sophomore album, It's About Time, came out on Polydor in Europe and the UK. Even though it wasn't distributed in the United States, T.O.N.T.O. synthesizer made a Hollywood cameo, appearing in Brian De Palma's comedy/horror Phantom of the Paradise in October 1974. The following year, Atlantic re-released the band's debut album with an alternative artwork in the USA/Canada. Gil Scott-Heron & Brian Jackson used the T.O.N.T.O. synth on their 1980 album on Arista, pictured with the instrument on the front and back covers. In 1975, Malcolm Cecil bought out Bob Margouleff's share and became the sole owner of T.O.N.T.O. synthesizer. In the mid-1990s, the system resided at Mutato Muzika studios in West Hollywood, a home base of Devo's co-founder Mark Mothersbaugh, before returning to Cecil's home in Saugerties, New York. In 1996, the Tonto Rides Again CD compilation came out on Viceroy, featuring tracks from Zero Time and It's About Time albums. (Ten years later, Malcolm Cecil privately reprinted it as a limited edition CD with a bonus track).
In late 2013, the Canadian National Music Centre in Calgary, Alberta, purchased T.O.N.T.O. from Cecil, placing it on the public exhibit. John Leimseider at NMC completed a multi-year restoration in 2017, repairing all broken components and worn-out jacks so the instrument is fully playable.