Each bandpass has it's own triangle LFO with adjustable frequency and amplitude ,modulating the cutoff frequency. Instead of the internal LFO an external control voltage may be used. In this case the CV is fed into the external CV jack (with integrated switch to turn off the LFO signal) and the LFO's amplitude control affects the CV modulation intensity instead.
Each filter is equipped with the following controls: LFO frequency, LFO/external CV amplitude, cutiff frequency, resonance and filter amplitude. In addition to the mix output for all three filters each filter has a separate audio output. The original audio signal can be added to the triple filter mix signal with a separate control.
The filters share a common audio input with attenuator. The filter audio inputs are very sensitive so that distortion may intentionally be used to create new sounds - if desired.
The frequency control range of the bandpass filters is about 40Hz...6kHz, the frequency range of the LFOs is about 0.02Hz...20Hz (= 1 min ... 1/20 sec per cycle).
Each filter can used also as a 12dB low pass instead of band pass. For this a jumper has to be changed on the according filter board. In this case the module can't be called any longer a "resonance filter" but "triple low pass filter". It is also possible to change the characteristic for only one or two filters, up to you.
For the A-127 a breakout expander is available, which gives you a separate audio in per filter and acces to four different filter types of each filter.
common audio input, mix output
per filter: cutoff CV input, filter output
3U Eurorack module, 28HP wide, 55mm deep
Current draw 100mA