on a Turnabout Records "Electronic Music" compilation. Other known, but unreleased student compositions include "Episodes for Piano and Tape" (1964), "Pomposities for Narrator and Tape" (1965), and "Noah" (1965), a two-hour opera blending electronics with an orchestra. Carlos's first commercial release was Moog 900 Series – Electronic Music Systems (1967), an introduction to the technical aspects of the Moog synthesizer released as a nine-minute single-sided mono LP and narrated by Ed Stokes. Part of her compensation for making the recording was in Moog equipment, and in part payment for her various other contributions to Moog's product development, and for articles she wrote for his short-lived electronic music periodical, she was able to acquire additional Moog equipment at a discount, most of it custom-designed to her specific requirements. By the time Carlos began recording Switched On Bach she had built a home studio valued at around US$12,000 (approx. $100,000 in 2023) (although, given the unique nature of most of the modules, and their provenance, the actual value of her studio equipment today would likely be far higher). Her home studio, crucially, included an eight-track recorder that Carlos had built herself (because she was unable to afford a factory-made machine), using parts from Ampex and EMI recorders, with the addition of Ampex's patented "Sel-Sync" system, which enabled recorded signals to be monitored via the record head, rather then the playback head, thus permitting multiple tracks to kept in perfect synchronisation. Carlos was also one of the earliest adopters of the Dolby noise reduction system, which she used for her final two-track masters. Switched-On Bach In 1968, Carlos released Switched-On Bach, an album formed of several pieces by Johann Sebastian Bach performed on a Moog modular synthesizer. Carlos had originally wanted to record an album of her own music, but Elkind suggested that they use music that was more familiar to the general listener in order to introduce the synthesizer as a credible new instrument. The idea for an album of Bach's music performed on the Moog began to crystallize during 1967, after Carlos asked Elkind to listen to some recordings by Carlos and musicologist Benjamin Folkman made up to ten years prior at the Electronic Music Center, one of them being Bach's Two-Part Invention in F major, which Elkind took a liking to. Plans for an album of several Bach compositions developed from there. From her experience working in the music industry,