doepfer a-109 voltage controlled signal processor (vcf - vca - panning) price : $175.00

module a-109 is a voltage controlled audio signal processor containing the following components:
* vcf: 24 db low pass with voltage controlled resonance
* vca
* pan: panning unit (two complementary controlled vcas)

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).

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.