Tuesday, April 23rd, 2019 11:33 pm
"The Prophet 5 contains five individual voices. For its principal sound sources each voice contains two VCO's
(voltage controlled oscillators), OSC A and OSC B, and a white noise source which can be mixed into a resonant
low-pass VCF (voltage controlled filter). The filter modifies the voice timbre under control of its four-stage
envelope generator. The filter may also be resonated and serve as a sound source. Following each filter, a VCA
(voltage controlled amplifier), also controlled by a four-stage envelope generator, shapes the voice amplitude.
Supplementing the basic voices are polyphonic modulation (POLY-MOD) signal routings within each voice that
allow OSC B and the filter envelope generator to function as modulation sources applied to OSC A frequency or
pulse width, or the filter frequency. Finally, there is a single LFO (low-frequency oscillator) and a pink noise source
which can be mixed to modulate all five voices, as adjusted by the MOD wheel.
"The Prophet-5 sustained six revisions (or revs). Rev 1 was the original design. Rev 2 was a refinement of the
original design and largely transparent. Rev 3, however, was a vastly different synthesizer than Revs 1 and 2.
Introduced to Rev 3 were new voltage controlled IC's (CEM), an improved ADC, DAC, and a different control
voltage distribution scheme. More sophisticated editing and tuning routines were designed, and to improve
servicibility, voice trimmers were reduced from 80 to 45. Some believe that the Rev 3 synthesizers are slightly
inferior (sonically) to their predecessors by revealing an absence in the lower frequencies. While this may be true,
the majority of the Rev 3 synthesizers are far more operationally stable than their Rev 1 and Rev 2 counterparts.
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