MFB - VCF-SED

The VCF-SED module is a voltage controllable low pass filter as a single ended discrete design, using transistors that can be driven into clippng zone for a great sound.

The filter module has two audio inputs with input 1 offering variable attenuation. When not patched the filter output is fed back into this input. By this, it is easy to recreate the legendary feedback-trick that leads to additional pushing bass. Input 2 has a fixed input sensitivity that matches the Mix output of MFB's oscillator module OSC-03.

Filter cutoff can be controlled manually as well as from CV-sources. CV-1 is adjustable in intensity and intended to be used with an envelope generator. CV 2 has two functions: It accesses the internal Key CV-voltage provided by the system-bus (when fed by a MIDI/CV-interface). This allows for easy key-tracking for the cutoff-frequency. Tracking-intensity can be adjusted by a trim-potentiometer. An additional front-panel-input allows adding a further CV source (e.g. LFO) that uses the same potentiometer. To use this input independently, the system-bus-access can be disabled by setting a jumper on the circuit board.

Filter resonance, called emphasis, can also be adjusted manually and by an adjustable CV input.