Sequential Circuits Prophet-5: Difference between revisions
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== Significant electronics == |
== Significant electronics == |
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The Prophet's eleven oscillators – two per voice and one LFO, are based on the [[ |
The Prophet's eleven oscillators – two per voice and one LFO, are based on the [[CEM3340]] VCO IC, (before Rev 3 the [[SSM2030]]). 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" /> |
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The Prophet's five low-pass filters are based on the [[ |
The Prophet's five low-pass filters are based on the [[CEM3320]] VCF, (before Rev 3 the [[SSM2040]]). 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" /> |
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The filter and amplifier envelope generators are based on the [[ |
The filter and amplifier envelope generators are based on the [[CEM3310]], (before Rev 3 the [[SSM2050]] 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" /> |
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The voltage controlled amplifiers are based on the [[CA3280]] transconductance op-amp IC (before Rev 3 the [[ |
The voltage controlled amplifiers are based on the [[CA3280]] transconductance op-amp IC (before Rev 3 the [[SSM2020]]).<ref name="techman" /> |
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A [https://en.wikipedia.org/wiki/Zilog_Z80 Z80] [[CPU]] keeps the VCOs in tune, generates most [[CV/Gate|CVs]] from [[patch memory]] or panel knobs and switches, and assigns the voices to the keys being played.<ref name="techman" /><ref name="mbll" /> |
A [https://en.wikipedia.org/wiki/Zilog_Z80 Z80] [[CPU]] keeps the VCOs in tune, generates most [[CV/Gate|CVs]] from [[patch memory]] or panel knobs and switches, and assigns the voices to the keys being played.<ref name="techman" /><ref name="mbll" /> |