Befaco - i² Instrument Interface


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The i² Instrument Interface has to be considered a practical tool for extracting voltages from an injected audio signal, e.g. to generate dynamic modulations by various control voltages and to generate triggers and gates. The module has a pre-amp and a band pass filter as well.


The module consists of a number of circuits: first of all there's a pre-amplifier with big and small input jacks and a gain potemtiometer for setting the amplification. The pre-amp is followed by a band pass flter with adjustable center frequency and width for eliminating unwanted signal portions, like bassdrums which, due to their high energy mask other frequencies' level and cut a lot of dynamics from the envelope follower.

The pre-amplified and filtered signal is available at the audio out but is being sent simultneously to the other function blocks:

  • Envelope Follower follows the audio signal's amplitude changes- Three selectable velocity responses.
  • Envelope Regenerator: generates an Attack-Decay envelope from the audio signal; with adjustable time parameters.
  • Trigger Extractor: A comparator that produces a gate and a trigger when the audio signal exceeds a threshold. The gate remains high until the audio level drops below the threshold again.


pre-amp: 3,5mm and 1/4" inputs
bandpass filter: audio out
envelope follower: voltage output "follo"
envelope regenerator: voltage output "rege"
trigger extractor: trigger out, gate out


3U Eurorack module, 11HP wide, 45mm deep
power consumption: 40mA @ +12V and 35mA @ -12V

0.25 kg
Article Number

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