| I'll try to help, but please remember all of this depends on your bass, strings, pickup, and the
sound you get from your hands. I would start with
the tone controls in the neutral position (with the marks on the knobs pointing straight up up).
I use a GK150MB and I typically leave the controls
neutral except for the "high mid" knob which I reduce a bit to take out some of the high "nasal" sound. The contour control boosts the lowest and
highest frequencies, which helps give you a sound which might be described as "focused". Using too
much of this control might lead to a sound which is too "boomy" and also might make the high frequencies harsh sounding. Try and experiment...the settings which sound best when playing alone might be different than when playing with a group, and they can also change depending on the volume of the amplifier. I hope this helps...
Scott Mc......St Paul, MN USA | 
