SubFilter is a subsonic filter with a selectable cutoff slope of -12, -24 or -36dB/Octave. The filter is extremely useful for removing thumps, bumps and low frequency rumble noise from your audio. The filter has 2 controls: cutoff slope and cutoff frequency. The cutoff frequency is variable from 10Hz to 200Hz. The passband is flat (Butterworth filter) and has unity gain.