[2] In the same year he built a monophonic synthesizer, which he called the Musitron, out of a clavioline heavily enhanced with additional resistors, television tubes, and parts from household appliances, old amplifiers, and reel-to-reel tape machines.
The sound of the Musitron was influential on other musicians and producers, including Gordy, Joe Meek, Ennio Morricone, John Barry, and Roy Wood.
During a live set one night at the Hi-Lo Club in Battle Creek, Michigan, Crook hit upon an unusual chord change going from A-minor to G, and he and Del Shannon co-wrote and developed the lick into a song, which became "Runaway".
When "Runaway" was hitting the top of the record charts in 1961, there was a contest on American Bandstand to guess the musical instrument playing on the bridge in the song.
Later in the 1960s, he worked as an electronic musical duo with Scott Ludwig, billed as "The Sounds of Tomorrow", performing instrumental versions of current hits.
[6] In the late 1960s, Crook and his family moved to California and worked as a burglar alarm installer and Ventura County Firefighter, before returning to recording with Del Shannon and Brian Hyland.