Sequential Circuits Prophet-5: Difference between revisions

[[File:Sequential Circuits Prophet-5 Rev 3.3.jpg|thumb|right|400px|Sequential Circuits Prophet-5 Rev 3.3]]The '''Sequential Circuits Prophet-5''' released in 1978, was the first completely programmable [[polyphony|polyphonic]] [[analog]] synthesizer. [[Dave Smith]] designed the electronics and coded the firmware.<ref name="oman">''[http://www.synthfool.com/docs/SequentialCircuits/Prophet_Series/Sequential%20Circuits%20Prophet%205%20Owners%20Manual.pdf Prophet-5 Synthesizer Operation Manual]'' by Stanley Jungleib, Synthfool.com</ref><ref name="vail">''Vintage Synthesizers'' by Mark Vail, Miller Freeman, 1993, {{ISBN |0-87930-603-3}}, pp. 173-177</ref><ref name="ko">''Keyfax Omnibus'' by Julian Colbeck, MixBooks, 1996, {{ISBN |0-918371-08-2}}, pp. 122-124</ref><ref>[https://www.davesmithinstruments.com/about/ About], Dave Smith Instruments</ref>

The Prophet-5 is five voice [[subtractive synthesizer]]. Each voice is an individual synthesizer with two [[VCO]]s (voltage controlled oscillators) osc A and osc B, a [[mixer]], a 24dB per octave four pole resonant low-pass [[VCF]] (voltage controlled filter) controlled by an ADSR [[envelope generator|EG]] (envelope generator) and a final [[VCA]] (voltage controlled amplifier) controlled by another ADSR EG. It also has a single [[LFO]] (low frequency oscillator) and pink noise source.<ref name="techman">''[http://www.synthfool.com/docs/SequentialCircuits/Prophet_Series/Sequential%20Circuits%20Prophet%205%20Technical%20Manual.pdf Sequential Circuits Prophet 5 Technical Manual]'' by Stanley Jungleib, Synthfool.com, s. 2.2</ref><ref name="mbll">[httphttps://web.archive.org/web/20060910020427/http://users.adelphia.net/~cygnusx_1/prophet5.html Prophet 5 Synthesizer] by Matt Bassett</ref>

* Revision 1, , instrument code 1000.1, serial numbers 1-182. The least common. Uses [[Solid State Micro Technology Forfor Music|SSM]] ICs. These were very unreliable. Cannot be retrofitted for [[MIDI]].<ref name="techman" /><ref name="mbll" /><ref name="forrest">''The A-Z of Analogue Synthesisers Part Two'' by Peter Forrest, Short Run Press Ltd, 1996. p. 114.</ref><ref name="reid" />

The Prophet's eleven oscillators – two per voice and one LFO, are based on the [[CEM 3340CEM3340]] VCO IC, (before Rev 3 the [[SSM 2030SSM2030]]). The IC is scaled at 1V/octave. This means that an overall CV change of 1V ideally produces a pitch change of exactly one octave. So, a CV change of 1/12V (83.3 mV) changes pitch by one semitone.<ref name="techman" /><ref name="mbll" />

The Prophet's five low-pass filters are based on the [[CEM 3320CEM3320]] VCF, (before Rev 3 the [[SSM 2040SSM2040]]). Its scale matches the VCO scale of 1V/OCT, so it is also adjusted in semitones by 83-mV DAC steps.<ref name="techman" /><ref name="mbll" />

The filter and amplifier envelope generators are based on the [[CEM 3310CEM3310]], (before Rev 3 the [[SSM 2050SSM2050]] EG). Its output is a positive DC voltage whose level changes over the time periods set by the input timing CV's. When applied to the VCF and the final VCA the transient voltage determines the frequency and amplitude contours of the voice.<ref name="techman" /><ref name="mbll" />

The voltage controlled amplifiers are based on the [[CA3280]] transconductance op-amp IC (before Rev 3 the [[SSM 2020SSM2020]]).<ref name="techman" />

A [https://en.wikipedia.org/wiki/Zilog_Z80 Z80] [[CPU]] keeps the VCOs in tune, generates most [[CV/Gategate|CVs]] from [[patch memory]] or panel knobs and switches, and assigns the voices to the keys being played.<ref name="techman" /><ref name="mbll" />

* [https://web.archive.org/web/20161008052906/http://users.telenet.be/prophet-5/main.htm Sequential Circuits Prophet 5 Tribute Site]

* [httphttps://web.archive.org/web/20061231234110/http://users.adelphia.net/~cygnusx_1/prophet5_mod.html Modification for the rev.3] by Juergen Haible