Sequential Circuits

Sequential Circuits Inc. (SCI) was a San Francisco Bay Area-based synthesizer company that was founded in the early 1970s by Dave Smith, and sold to Yamaha Corporation in 1987. Throughout its lifespan, Sequential pioneered technologies and design principles that have served as a foundation for the development of modern music technology. Sequential was also pivotal in the planning, design, and support of 1982's groundbreaking innovation in electronic music, MIDI.

Following the purchase of Sequential Circuits by Yamaha, Dave Smith continued to develop musical instruments through Dave Smith Instruments. In January 2015, he reacquired the rights to use the Sequential brand name from Yamaha president Takuya Nakata.

Sequential's first products were sequencers and programmer devices for third-party synthesizers.

Sequential's first synthesizer, the brainchild of Dave Smith and John Bowen, was the very successful Prophet-5, released in 1978. This was the first affordable, fully programmable polyphonic analog synthesizer, which enjoyed considerable popularity in the early 1980s. By combining full microprocessor control with low-cost synthesizer module chips (initially by Solid State Music and later Curtis Electromusic), Sequential was able to produce a relatively low-cost synthesizer with five voices of polyphony. The then-revolutionary principle of combining five analog voices with easy editing and programming within a compact format established a new standard for polyphonic instruments. With the addition of patch storage (an innovation by Dave Smith with assistance from E-mu's Dave Rossum) the user was able to cycle through up to one-hundred sounds at the push of a button. These were viewed as remarkable developments in the synthesizer industry, especially from a previously unknown company that operated out of a California garage. Dave Smith designed, programmed, and built the Prophet 5 in less than eight months. The Prophet-5 was in production from 1978–1984, and sold approximately 8,000 units.

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