Boomstick is modeled after the basic Sallen-Key filter architecture. The original circuit I built was very minimalist; just a couple of capacitors, vactrols and operational amplifiers. However, one thing I removed from this model was the vactrol behavior since I was aiming to get the simplest and best sounding filter model.
- Cutoff: this is the main knob in a filter. It defines the frequency at which the filter starts taking action. Full left, the filter is completely closed. Full right it's open and should not have effect. The cutoff frequency can be controlled with a 1V/Oct signal through the included attenuverter.
- Resonance: the resonance boost the frequencies near the cutoff frequency. Increase this knob and you will hear the personality of the filter. Ferox does not self-oscillate.
- Drive: controls the amount of signal that enters to the filter. Increasing the drive will cause the filter to saturate which adds interesting harmonics to the sound.
-Modulations: CV1 and CV2 are used to modulate the Cutoff of the filter.