Engineering:Prophet VS

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Short description: Polyphonic digital synthesizer
Prophet VS
Sequential Circuits Prophet VS
ManufacturerSequential Circuits
Dates1986-87
Technical specifications
Polyphony8
Timbrality2-part
Oscillator12-bit digital

4 per voice

96 preset & 32 user waveforms
LFO2
Synthesis typeVector
Sample & Synthesis (S&S)
FilterAnalog low-pass filter
Attenuator5-stage loopable envelope generator
Aftertouch expressionYes
Velocity expressionYes
Storage memoryInternal: 100 patches + 32 user waves
Cartridge: 100 patches + 32 user waves
EffectsStereo Chorus
Voice Panning
Input/output
Keyboard61-key
0 (rack version)
Left-hand controlPitch, Modulation
External controlMIDI

The Prophet VS was a hybrid 8-voice synthesizer manufactured by Sequential Circuits and released in 1986. It is notable for being the first synthesizer to use vector synthesis to structure its sound, using a joystick arranged in a "diamond" pattern for oscillator mixing.[1][2][3] Its distinctive sound comes from mixing four 12-bit digital single-cycle waves per voice, which are then fed into analog CEM3379/3389 signal processors for filtering and amplification.[1]

Features and architecture

Sound generation

The VS has 8 voices, each one featuring up to four digital oscillators. Each oscillator is chosen from a table of 0-126 12-bit single cycle waveforms, with the 127th selection being a noise generator.[1][4]

Waves 32-126 are programmed into the firmware EPROMs and cannot be externally modified. However, waves 0-31 are the user wave space and can be overwritten with custom samples utilizing the MIDI sample dump standard.[1] Another unique characteristic of the VS is that the user waves can be manually edited with the onboard wave editor, mixing up to 4 waves into a single one or adjusting individual harmonics similarly to additive synthesis.[4]

Each voice has a CEM3379/3389 analog signal processor which gives voltage control over the filter, amplifier, and panning. Modulation of panning CV utilizing the modulation matrix can create lush moving stereo patterns.[1][4]

Hardware

The VS uses an 8MHz Motorola 68000 as the main processor, along with two 27256 EPROMs for the operating firmware. Besides the usual 7400 & 4000 series logic chips, there are several unique or hard-to-find parts[5]

  • I-625 Voice Chip[6] x4 - Each unit uses these for Waves A-D. 8 digital oscillators plus noise generator. These are unique to the VS.
  • 68B01 Keyboard Controller - Scans the mechanical keyboard and calculates velocity values. Also used in the Prophet 2000.
  • CEM5510 x4 - 8-channel high-speed sample and hold. Used to fake VCAs for oscillator mixing. These are unique to the VS.
  • CEM5530[7] x2 - 30-channel sample and hold. Used to fake VCAs for voice mixing.[8] This is a common point of failure, and several aftermarket replacements are available. Also used in the Studio 440 and Keytek CTS-2000.
  • CEM3365[9] x2 - Dual DAC multiplier.
  • CEM3379[10] or CEM3389 x8 - Analog VCF, VCA, and voltage-controlled panning.

Legacy

After Sequential was acquired and shut down by Yamaha in 1989, Dave Smith and a handful of the development team moved to Korg, where they worked on developing the Korg Wavestation.[1][11] Yamaha then expanded upon the VS technology to create the Yamaha SY22 and SY35 in 1990, adding FM synthesis.[12]

In the 2020s, Behringer released two clones of the Prophet VS, a eurorack synth engine called the "Victor" and a miniature version of the complete synth called the "Pro VS Mini".[13][14]

While modernizing the appearance of the joystick for all following vector based instruments, functionally the "diamond" layout has been followed ever since.[8]

Notable users

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Alexander, Rob (November 2001). "Sequential Prophet VS". Sound on Sound. http://www.soundonsound.com/sos/nov01/articles/retroprophetvs.asp. 
  2. ↑ Jungleib, Stanley (November 1986). "Introduction to Vector Synthesis". Electronic Musician: 53–54. http://www.seersystems.com/jungleib/archive/1986/86%20INTRO%20VECTOR%20EM%20ART.jpg. 
  3. ↑ Jenkins, Mark (July 1986). "Sequential's Prophet VS...". Sound on Sound: 26–28. https://www.muzines.co.uk/articles/sequentials-prophet-vs/1617. 
  4. ↑ 4.0 4.1 4.2 Mills, Tony (August 1986). "Sequential Prophet VS". International Musician and Recording World: 104–107. https://www.muzines.co.uk/articles/sequential-prophet-vs/11087. 
  5. ↑ "Sequential Circuits Synthesizers". https://winecountrysequential.com/page15.html. 
  6. ↑ "SequentialCircuits.com". https://www.sequentialcircuits.com/prophetvsparts.html. 
  7. ↑ "30 Channel sample & hold - Preliminary". January 1987. http://www.retrosynth.com/docs/pvs/5530.pdf. 
  8. ↑ 8.0 8.1 ""The Story of the Prophet VS - from the VS WaveWrangler User Guide, 1991"". 30 January 1991. https://learningmodular.com/the-story-of-the-prophet-vs/. 
  9. ↑ "CEM3365 Fast Dual DAC Multiplier". http://www.synfo.nl/datasheets/CEM3365.pdf. 
  10. ↑ "CEM3378/3379 Voltage Controlled Signal Processors". http://www.buchty.net/ensoniq/files/cem3379.pdf. 
  11. ↑ Reid, Gordon (November 2002). "The History Of Korg". Sound on Sound. https://www.soundonsound.com/music-business/history-korg-part-2. 
  12. ↑ 12.0 12.1 12.2 ""Blast from the past: Sequential Circuits Prophet VS"". Computer Music. 27 April 2015. https://www.musicradar.com/news/tech/blast-from-the-past-sequential-circuits-prophet-vs-619031. 
  13. ↑ "Behringer introduces Victor Eurorack module with a PRO-VS Mini engine" (in en-GB). https://musictech.com/news/gear/behringer-victor-module-eurorack-pro-vs-mini-engine/. 
  14. ↑ Anatomy, Synth (2024-12-13). "Behringer Pro VS Mini 2.0, hybrid vector synth now with more voices, new FXs, and more" (in en-US). https://synthanatomy.com/2024/12/behringer-pro-vs-mini-2-0-hybrid-vector-synth-now-with-more-voices-new-fx-and-more.html. 
  15. ↑ Tingen, Paul (July 2016). "John Carpenter". Sound on Sound. https://www.soundonsound.com/people/john-carpenter. 
  16. ↑ Tudahl, Duane (November 2021). Prince and the Parade and Sign O the Times Era Studio Session: 1985 and 1986. Rowman & Littlefield. ISBN 9781538144510. 
  17. ↑ Rule, Greg (1 March 1994). "Trent Reznor". Keyboard Magazine. https://www.theninhotline.com/archives/articles/display/548. 
  18. ↑ Hanson, Robert (1 May 2005). "Trent Reznor sheds the excesses of the past...". Remix Magazine. https://www.theninhotline.net/archives/articles/display/55. 
  19. ↑ Secret, Jack (July 1997). ""Rush's Live Midi Secrets Revealed"". EQ Magazine. http://www.2112.net/powerwindows/transcripts/19970700eq.htm. 

Further reading

  • "Introduction to Vector Synthesis" - Stanley Jungleib, Electronic Musician November 1986 p.53, p.54

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