home contact

Saturday, October 20th, 2018 11:50 pm

Synth Glossary

A filter filters out certain frequencies in the sound. There are four main types: a low-pass, high-pass, band-pass and notch, which are covered elseware in the glossary. Filters have two controls - the frequency control selects at which frequency the filter should start operating and the resonance control creates a peak just before the bit where it starts filtering out frequencies. This is used to create acid-type sounds....


"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.

Hosted by Jesse Mullan