Sequential Circuits

Founded in the year:1977
First Product:Sequential Circuits Prophet 5
Location:Sunnyvale, California | map location

Sequential Circuits is a synthesizer company founding the early 1970s by Dave Smith. Sequential Circuits (also known as Sequential or SCI) was a synth manufacturer formed in 1977. The founders were Dave Smith and John Bowen on the technical side, and Barb Fairhurst taking care of the business side of the operation. They released a sequencer, the Model 700, that year. In the meantime, they were working on the ground-breaking Prophet-5, which they released in 1978. The Prophet-5 dominated the market for polyphonic synthesizers until 1983. In the meantime, the company released a variety of variations on the Prophet-5 theme, both polyphonic and monophonic. The high point of this period was probably the Prophet-T8, an eight-voice synth with a piano-weighted keyboard with polyphonic aftertouch.

In the mid-’80s, the company delved into samplers, with the Prophet 2000 and 3000. These were well-liked by the performers who bought them, but they were priced higher than the comparable models from E-mu Systems, and sales were slow. The company’s last product was the Prophet VS, the first synth to use the vector synthesis concept. The Prophet VS was released just months before the company collapsed in 1987. In December of that year, Yamaha acquired the company and shut down its production. They sold the remaining stock, along with technical documentation and software, to Wine Country Productions. Wine Country has been offering parts and service for vintage Sequential Circuits synths for many years, but their parts stock is now nearly depleted.

The Sequential Circuits Prophet-5

The Sequential Circuits Prophet-5, released in 1978.

A team of engineers led by Smith went to work for Yamaha after the acquisition of Sequential They designed the SY22 and TG33 vector synths for Yamaha. Later, Yamaha assigned them to do projects for Korg, which Yamaha owned at the time. The group developed the Korg Wavestation, which was basically a re-creation of the Prophet VS with some improvements.

Sequential was instrumental in the development of MIDI. The company had developed a proprietary remote control bus for the Prophet-5, as had Roland for its products of that era. A chance meeting between Smith and Roland’s Ikutaro Kakehashi led to the formation of a trade group that developed the original MIDI standard. In 1982, Sequential’s Prophet-600 became one of the two first synth models to be factory-equipped with MIDI, along with Roland’s JX3P. Smith and Kakehashi received Grammy awards in 2013 for their work on MIDI.

Smith launched a new synthesizer manufacturing company, Dave Smith Instruments, in 2002. In 2015, DSI acquired the rights to the Sequential Circuits name and trademarks. They launched the Prophet-6, a re-creation and update of the Prophet-5, under the Sequential name.

Sequential Prophet 5 Audio Demo
A demo of my Sequential Prophet 5 (Ver 3.2). Sounds are recorded with a little reverb and delay added but no other effects.

Sequential Prophet 5 Audio Demo

  • Model 600 (1974) – analog sequencer
  • Model 800 (1975) – digital sequencer
  • Model 700 (1977) – programmer
  • Prophet-5 (1978) – 5-voice analog synthesizer with patch memory
  • Fugue (1979) – ensemble keyboard, designed by SCI and built by Siel
  • Prophet-10 inside
  • Pro-One (1980)
  • Prophet-10 (1980) – essentially two Prophet-5s in one large enclosure
  • Pro-One (1980) – basically a monophonic version of the Prophet 5
  • Pro-FX (1982) – the first programmable modular effects units
  • Prelude (1982) – 4 section orchestral synthesizer, manufactured by Siel; a silk screen variation of Orchestra 2 and OR400
  • Prophet 600 (1982) – the world’s first MIDI synthesizer
  • Prophet Remote (1982) – remote keyboard for Prophet-5;[15] the interface was Serial Control Buss (SCB).
  • Prophet T8 (1983) – The first “piano action” MIDI synthesizer
  • Model 64 Sequencer (1983) – software MIDI sequencer with MIDIinterface, in the form of Commodore 64 cartridge
  • Six-trak (1984) – the first multi-timbral synthesizer
  • Drumtraks (1984) – programmable drum machine with MIDI
  • Split-8
  • Pro-8 (1985)
  • MAX (1984) – 6 voice synthesizer controlled by external PC
  • MultiTrak (1985) – Sequential’s second multi-timbral synthesizer
  • Split-8 / Pro-8 (1985) – 8-voice synthesizer
  • TOM (1985) – advanced programmable drum machine
  • Prophet 2000 (1985) – 12bit sampler
  • Prophet VS (1986) – the first vector synthesizer
  • Studio 440 (1986) – music production machine with sequencing/sampling drum
  • Prophet 3000 (1987) – 16bit sampler, the final Sequential Circuits product
  • Prophet-6 (2015) – fully analogue synthesizer, loosely based on the Prophet 5


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