I just bought a MIM Fender Deluxe Precision active bass with the P and J pickups. I think it is about a 2008 model. I can't figure out the knobs. I know front one is master volume and the stacked one is bass and treble boost. I can't seem to figure out the other two. Can anyone explain? Thanks. (I am new to this site but searched around and don't see this question raised and answered).