The RFM or Resonance Filter Module can be compared to a parametric equalizer. It has three sections. Each section is a bandpass filter whose output is added on top of the original signal to add/amplify a chosen frequency band so as to give it a more distinct resonance on that set frequency. The f0 knob sets the middle frequency of the band, while the Q-knob sets the ‘quality’ or resonance of that filter. The higher the setting, the smaller the band. The height of the band is set with the A (amplitude) knob. The RFM-module becomes extra effective when trying to mimic instrumental sounds like strings or brass. Those instruments often have their own specific ‘resonance frequency’ (think of a violin or guitar for instance) When you look up such a frequency and set that with the f0 knob and dial in Q- and A-settings, the sound should come closer to the original. When creating original sounds RFM might help to make it sound more natural or just exaggerate some frequency to make the sound stand out more. Below every f0-knob is an input to modulate that center frequency. The input (top left) level is set with the green knob. To have the RFM output its affected sound, the button needs to be switched on.