The Heisenberg’s filter block consists of one to four bi-quad resonant filters connected in series whose frequency responses are determined by their coefficients. The filter section provides controls to set its cutoff frequency, resonance, order and keyboard tracking.
- Cutoff/Resonance: This 2D slider sets the cutoff frequency and the amount of resonance of the filter simultaneously. You can set the cutoff frequency as a percentage of a range going from 20 Hz at minimum to 20 KHz at maximum. The resonance goes from none at minimum to full at maximum. Note: Due to the filter’s design, increasing the resonance also reduces the amplitude of the passband up to approximately 10 dB at maximum resonance.
- Filter mix: This slider sets the frequency response of the filter as a percentage from low-pass at minimum through bypass at center to high-pass at maximum. It does this by setting the coefficients of all bi-quad filters.
- Order: This selector sets the filter roll-off to either 12, 24, 36 or 48 dB per octave. It does this by serially cascading an additional bi-quad filter for each successive order.
- Keyboard track: This slider sets the amount by which the pitch of incoming notes modulates the cutoff frequency of the filter from approximately 33% of the filter’s frequency range per octave below the cutoff at minimum through no modulation at center to 33% of the filter’s frequency range per octave above the cutoff at maximum. Note: A C4 note produces no modulation and is the reference pitch from which the modulation produced by other notes is measured.