*THIS MODULE IS USED AND HAS BEEN FULLY TESTED BY NERD AUDIO *
Module A-109 is a voltage-controlled audio signal processor consisting of the following units:
VCF: Voltage-controlled 24 dB low-pass filter with voltage-controlled resonance
PAN: panning unit (two counter-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).