The Gap Filter marks the third effect and provides further filtering of the signal. It consists of two four-pole filters (with a damping slope of 24 dB per octave) which can run in parallel or in series. The filter types are static, as the first filter is a highpass, followed by the second (lowpass) filter.
The filter frequencies can be determined by a Center
frequency, which can be spread in the stereo field and shifted by the Gap
parameter, creating an offset between the high- and lowpass filters. The filter resonance can be adjusted as well, creating two resonance peaks in the signal spectrum.
Both filter outputs can be blended by a Balance parameter, defining a crossfade mix of the two components.
The bipolar Mix parameter determines the amount of filtering in the resulting signal, crossfading the input signal with the filtered signal. Positive mix values mean that the filter components run in parallel, resulting in a band-reject behavior. Negative values produce a bandpass effect, as the filter components are running in series.