Prophet VS

Prophet VS
Sequential Circuits Prophet VS
Manufacturer	Sequential Circuits
Dates	1986-87
Technical specifications
Polyphony	8
Timbrality	2-part
Oscillator	12-bit digital 4 per voice 96 preset & 32 user waveforms
LFO	2
Synthesis type	Vector Sample & Synthesis (S&S)
Filter	Analog low-pass filter
Attenuator	5-stage loopable envelope generator
Aftertouch expression	Yes
Velocity expression	Yes
Storage memory	Internal: 100 patches + 32 user waves Cartridge: 100 patches + 32 user waves
Effects	Stereo Chorus Voice Panning
Input/output
Keyboard	61-key 0 (rack version)
Left-hand control	Pitch, Modulation
External control	MIDI

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

• John Carpenter ^{[12] [15]}
• Prince ^[16]
• Trent Reznor ^{[12] [17] [18]}
• Rush ^[19] - The VS Choir is featured prominently on the album Hold Your Fire .

References

1. Alexander, Rob (November 2001). "Sequential Prophet VS". Sound on Sound . Archived from the original on 1 February 2016.
2. Jungleib, Stanley (November 1986). "Introduction to Vector Synthesis". Electronic Musician . pp. 53–54. Archived from the original on 27 September 2007.
3. Jenkins, Mark (July 1986). "Sequential's Prophet VS..." Sound on Sound . pp. 26–28.
4. Mills, Tony (August 1986). "Sequential Prophet VS". International Musician and Recording World . pp. 104–107.
5. "Sequential Circuits Synthesizers".
6. "SequentialCircuits.com". www.sequentialcircuits.com. Retrieved 2025-08-26.
7. "30 Channel sample & hold - Preliminary" (PDF). January 1987. Archived from the original (PDF) on 2003-03-10.
8. ""The Story of the Prophet VS - from the VS WaveWrangler User Guide, 1991"". 30 January 1991.
9. "CEM3365 Fast Dual DAC Multiplier" (PDF). Archived from the original (PDF) on 2014-12-14.
10. "CEM3378/3379 Voltage Controlled Signal Processors" (PDF). Archived from the original (PDF) on 2000-08-31.
11. Reid, Gordon (November 2002). "The History Of Korg". Sound on Sound .
12. ""Blast from the past: Sequential Circuits Prophet VS"". Computer Music . 27 April 2015.
13. "Behringer introduces Victor Eurorack module with a PRO-VS Mini engine". MusicTech. Retrieved 2025-04-16.
14. Anatomy, Synth (2024-12-13). "Behringer Pro VS Mini 2.0, hybrid vector synth now with more voices, new FXs, and more". SYNTH ANATOMY. Retrieved 2025-04-16.
15. Tingen, Paul (July 2016). "John Carpenter". Sound on Sound .
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 .
18. Hanson, Robert (1 May 2005). "Trent Reznor sheds the excesses of the past..." Remix Magazine .
19. Secret, Jack (July 1997). ""Rush's Live Midi Secrets Revealed"". EQ Magazine .

External links

• The Prophet VS at Sound On Sound
• Prophet VS Information

Further reading

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