Most guitar overdrive pedals tailor the sound before and after the clipping stage. This results in a loss of bottom end, as too much bass in an overdriven sound can make the sound "flabby". We take the signal from the bass guitar and split it. One path goes straight to the output via the DRY volume control, the other path goes through a high pass filter (to remove the flab from the overdrive) and then to a double clipping stage so as the signal level increases each different clipping stage contributes accordingly. This signal then goes to the CONTOUR circuitry and to the WET volume control. By changing the levels of DRY and WET you can easily vary the balance between the two signals. By keeping the original signal, we retain a warm bottom end and we add in as much dirt up top as is desired.