|The Resonance Filter Module (also called RFM or Parametric Equalizer) accentuates certain frequencies in the spectrum of a synthesizer sound. This module here consists of three identical resonance filters and is therefore able to emphasise three different frequency points in the spectrum at one time.
The main task of this module is to reproduce / simulate the natural resonance behaviour of natural instruments.
The input synthesizer sound can be attenuated by the input level pot. If the Bypass switch is on, the signal is sent to the output without manipulation.
Otherwise the input signal is passed to the three resonance filters and mixed to a summing signal at the output. Each resonance filter has three pots, f(0), Q and A.
With the f(0)-pot one moves thru the frequency spectrum and determines the point within this spectrum where accentuation has to be done.
With the Q-pot one determines the quality of the filter meaning how "large" or "small" is the frequency range which has to be accentuated.
The A-pot determines the amplification of the accentuated part of the frequency spectrum.
This circuit is not part of the Formant Pro - book but belongs to the second Formant book of the 70's.
Sound example (first half of each example without, second with RFM Module):