MFB VCF-SED is a filter module for modular synthesizers in Eurorack format, a voltage controlled low pass filter, which is single ended and discrete (transistors) and behaves significantly less noisy than other filter modules. It offers a dreamy sound and is easy to drive into the clipping zone. The filter module has two audio inputs for feedback.
The cutoff frequency of the MFB VCF-SED filter can be controlled manually and via the CV inputs. The adjustable input CV 1 is intended for the standard modulation by an envelope curve. CV 2 has a dual function: This is the internal key CV voltage of the system bus (if supplied by a MIDI/CV interface), which allows direct keyboard tracking of the cutoff frequency. The tracking intensity is set by a trim control. In addition, an additional CV voltage can be fed to the cutoff control via the front CV 2 input, for example by an LFO, the intensity of which is also adjusted with the Key CV trim control. The internal connection to the key CV of the system bus can be interrupted for independent handling of the second CV input via jumper. The resonance can be controlled manually with the Emphasis potentiometer and modulated via an attenuatable CV input.
Input 1 has an attenuator and, if the input is not connected, is fed back to the output of the filter. This makes it easy to implement the popular feedback trick, which provides an additional bass boost. Input 2, which cannot be controlled, is adapted on the level side to the mix-out of the oscillator modules OSC-03.