The filter can be:
- Lowpass filter: cuts all frequencies above the filter cutoff frequency.
Only the lower frequencies pass (hence the name).
- Bandpass filter: cuts both frequencies higher and lower than the filter cutoff frequency.
Only a certain band of frequencies pass (hence the name).
- Highpass filter: cuts all frequencies below the filter cutoff frequency.
Only the higher frequencies pass (hence the name).
- Notch filter: cuts frequencies in a range around the filter cutoff frequency and passes all frequencies lower AND higher than that range.
- Tone control: boosts a small range of frequencies, but doesn't block the other frequencies.
- Sensitivity: controls how the filter responds to the input signal, at which input level the effect starts responding and how much the effect responds to the envelope of a certain input.
- Range: defines the frequency range in which the filter moves, this can be a low/high switch or a rotary pot.
- Depth: sometimes called range, defines the amplitude of the filter sweep.
- Up/Down Mode: selects if the filter moves up- or downwards in response to the input signal.
- Envelope Controlled Filters by Mike Beigel & Elliott Randall.
- The Technology of Auto-Wahs / Envelope-Controlled Filters by Mark Hammer.
- Note Processing for Guitar Effects by R.G. Keen.
autowah, auto-wah, touch wah, wah-wah, wha-wha dynamic filter, envelope filter