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Sequential Circuits | Prophet-10


This rarely seen monster analog synth is by far one of the fattest and nicest vintage synthesizers. The Prophet 10 is simply two glorious Prophet 5 synthesizers stacked together. That gives 10 voices with 20 of Sequential's unique analog VCO oscillators at 2 per voice for a big fat analog dream! The Version 1 series suffered from major overheating and unstable tuning problems making it clumsy and unreliable to use. It also had a standard 61 note keyboard and looked just like the P5. A modification was made to try to solve the heating problem by adding heatsinks on the back. The big Prophet 10 logo had to move, and has been resized because of that.

Then came a bigger and better looking stacked keyboard version (as seen above); to be known as Version 2. Better chips were designed which soon cured most of the overheating problems. While Rev. 1 & 2 Prophets used chips made by SSM (Solid State Microdevices) which were fatter sounding but less stable, the Rev 3 Prophets changed to CEM (Curtis Electronics Manufacturing) chips. These increased their stability and reliability. Some audiophiles think they sound thinner than the SSM chips. However tuning and other functions were still somewhat unstable.

Version 3 (pictured top) was by far the best and most stable. 20 oscillators (2 per voice), 10 voices, 2 independent 61 note keyboards and all the great sounds and editing facilities as the Prophet 5! Built in Tuning tones and Auto-Tuning functions help make sure you won't go out of tune. And top notch circuitry and design prevent overheating. Multiple keyboard modes allow for true flexibility for different performance / voicing needs! The Prophet 10 is a truly fat and classic analog instrument. 

Although each voice is keyed independently, all five voices in each polyphonic bank function from the same patch setting, and are therefore homophonous. However, each of the two 5-voice synthesizer banks can operate on a completely different program, and can be articulated independently via the two keyboard manuals. In other words, two different programs can be used at any one time. One is the UPPER program, with one 5-voice synthesizer usually tied to the upper keyboard, and the other is the LOWER program, with the other 5-voice synthesizer usually tied to the lower keyboard. 

Each synthesizer voice consists of two voltage-controlled oscillators (VCOs), a white noise source, a resonant low-pass voltage-controlled filter (VCF), a voltage-controlled amplifier (VCA), two envelope generators (one wired to the VCF and one wired to the VCA) and a 3-band equalizer (EQ). In addition, there are routings (via the POLY-MOD section) that allow for oscillator B and the filter envelope generator lo lunction as modulation sources which can be applied to the frequency or pulse-width of oscillator A, or the filter frequency. Finally, each 5-voice synthesizer bank has a single LFO which can be applied to all of its voices for various effects. The two LFOs (UPPER and LOWER) can also be combined (summed) and applied to both polyphonic synthesizers for other effects. 

The Prophet 10 also contains a microcomputer, which serves several purposes: it determines which voice is assigned to which key, it keeps the voices in tune, and (most importantly) it remembers preset voice patches which may be instantly recalled to program the voices. These preset programs are retained by the micro computer's memory even when the Prophet is turned off, thanks to a small battery with a 10-year life.


BrandSequential Circuits
Engine TypeAnalog
Voices (max)10
LFO1 LFO with rate
Engine Detailed2 OSC. per voice. square / pulse / tri / saw. Poly Mod. Rev1, 2 SSM, Rev3.x CEM
Filter (VCF)Low pass resonant VCF with ADSR
Envelope (VCA)ADSR
Memory32 patches
RecordingSequencer: Polyphonic 6 track (4,000 to 10,200 notes)
ControllersRev3. Built in Tuning tones and Auto-Tuning
Keys61 (Rev1) 2x61 (Rev2, 3)
Key typeKeys
Extra infoMidi retrofit on Rev3.x only
Produced:1980 - 1980
Legend: Obvious Y: Yes, N: No, N/A: Not Applicable
VCO Voltage Controlled Oscillator DCO Digital Controlled Oscillator
LFO Low Frequency Oscillator Sub Sub Oscillator
VCF Voltage Controlled Filter VCA Voltage Controlled Amplifier
Velocity As with a piano, the harder you hit a key, the louder the sound, unlike most organs which always produce the same loudness no matter how hard you hit a key. Aftertouch Pressing a key after you activated it. Channel Aftertouch, no matter which key, it will send a Channel message. Poly Aftertouch, sends the pressure per key instead of the whole channel.
Values for OSC, LFO, Filter, Envelope are per voice unless stated otherwise.


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