Edit Delay Designer filter cutoff in Final Cut Pro
Whereas the steps outlined in Edit taps in the Delay Designer Tap display in Final Cut Pro apply to most graphically editable parameters, the Cutoff and Pan parameters work in a slightly different fashion.
In Cutoff view, each tap actually shows two parameters: highpass and lowpass filter cutoff frequency. You can adjust the filter cutoff values independently by dragging the specific cutoff frequency line—the upper line is lowpass and the lower line is highpass—or you can adjust both cutoff frequencies by dragging between them.
When the highpass filter cutoff frequency value is lower than that of the lowpass cutoff frequency, only one line is shown. This line represents the frequency band that passes through the filters—in other words, the filters act as a bandpass filter. In this configuration, the two filters operate serially, meaning that the tap passes through one filter first, then the other.
If the highpass filter’s cutoff frequency value is above that of the lowpass filter cutoff frequency, the filter switches from serial operation to parallel operation, meaning that the tap passes through both filters simultaneously. In this case, the space between the two cutoff frequencies represents the frequency band being rejected—in other words, the filters act as a band-rejection filter.