DSI / Sequential Prophet 12 keyboard version. Courtesy of Sequential Inc.
A polyphonic synth with a hybrid analog/digital architecture, created by Dave Smith Instruments. The Prophet 12 was the second synth bearing the "Prophet" name created by DSI, and like the Prophet 08, the name stems both from the year it was designed (2012) and the number of voices.
The oscillator portion of the voice architecture is a further development of what DSI designed for the Evolver. Each voice has four digital VCOs, offering a choice of 16 waveforms, which can be waveshaped and morphed in various ways, depending on the chosen waveform. The oscillators can modulate each other using FM or AM methods, and can also be synced to each other. A "slop" control allows the user to dial in a desired amount of random frequency variation into each oscillator, to somewhat emulate the tuning imprecision of analog oscillators. The oscillator section also includes a suboscillator which produces a sine wave only.
The oscillator outputs for each voice flow into what DSI calls the "character" section. This contains a mix of waveform-altering effects. Two called "Girth" and "Air" consist of low pass and high pass filters respectively, which also add even-numbered harmonics to the signal, emulating the type of distortion that vacuum tube preamps introduce when overdriven. The other effects available are bit crushing and decimation. The output of this goes to the filter section, which contains two VCFs: a low pass unit which can be switched between two-pole and four-pole response, and a two-pole high pass filter. The output of this goes to the VCAs, which include distortion circuits for additional waveform mangling when desired.
Each voice has two LFOs with a variety of wave shapes available, and four HADSR-type envelope generators. Two of the envelopes are hardwired to the VCO cutoff frequency and the VCA output level, respectively. The other two, along with many other signals in the synth, can be routed via the extensive 26x97 modulation matrix, which has 16 crosspoints available. A feedback loop for each voice completes the voice architecture. (There are no onboard effects other than those in the Character section.) The output is stereo, and the voices can be individually spread over the stereo field.
The 12 voices can be configured into two divisions of six voices each, which act somewhat like two separate synths in one box. The two divisions can be split or layered across the keyboard span as desired, and the synth is bitimbral in this mode. Each division also has its own arpeggiator, and a "Layer B" set of outputs allows the two divisions to be output separately. Patch memory consists of 396 factory patches in ROM, and 396 user-writable locations, each containing a pair of patches for the A and B divisions. Performance controls consist of the five-octave, C-to-C aftertouch and velocity sensitive keyboard, pitch and modulation wheels, and a pair of ribbon controllers positioned such that they can be played individually using the index and middle fingers of the left hand.
The Prophet-12 was introduced in 2013. A tabletop version, with a smaller panel containing fewer discrete controls, was introduced the next year. The keyboard version went out of production in 2019 after a final 100 "Limited Edition" units with white panels were produced. The tabletop version is still in production as of August 2021.