Most filters do not completely suppress the portion of the signal that falls outside the frequency range defined by the Cutoff parameter. The slope, or curve, chosen for Filter 2 expresses the amount of rejection below the cutoff frequency in decibels per octave.
Slope buttons: Choose a Filter 2 slope: 12 dB, 18 dB, and 24 dB. The steeper the slope, the more severe the effect on signal levels below the cutoff frequency.
Fat button: Adds 24 dB per octave of rejection. Fat mode has a built-in compensation circuit that retains the sound bottom end. By comparison, the standard 24 dB setting tends to make lower end sounds less rich.