A-109 VC Signal Processor |
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Module A-109 is a voltage controlled audio signal processor containing the following components:
The VCF is a standard 4 pole low pass filter with voltage controlled resonance. The filter has a so-called "constant amplitude versus resonance design", i.e. the peak-to-peak output level remains within 6dB when the output waveform rings from added resonance. Manual controls for frequency and resonance are available as well as 2 CV inputs for both (one with attenuator). The frequency range is about 5 Hz ... 20kHz, resonance ranges from 0dB up to self oscillation. The main VCA has a combined exponential/linear control scale: exponential from about 0...+200mV (corresponding to about -100dB ... -20dB), linear from about 200mV...+5V (corresponding to -20dB...0dB). The "rounded" knee at the scale bottom allows an envelope to decay to zero with a natural exponential sound. Manual control for amplitude is available as well as 2 CV inputs (one with attenuator). |
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The gains of the panning VCAs are complementary, beeing equal and half of
maximum at about +2.5V CV. The control scales are linear between about +1
and +3.5V CV, becoming logarithmic beyond these extremes. Manual control
for panning is available as well as 2 CV inputs (one with attenuator). The audio in/outputs of the module are normalized, e.g. the VCF output is fed into the VCA input privided that no jack plug is inserted to the VCA audio input socket. The A-109 module is based on Doug Curtis' CEM3379 that was used in many Sequential™, Ensoniq™ and PPG™ synthesizers. The A-109 will be manufactured as a limited edition because the CEM3379 is no longer in production, but we purchased a limited quantity of these circuits. The English manual will be available about February 2003. |
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Width: 20HP, Current: 40mA | |