Hello everyone, I don't understand what the internal potentiometers in the cavity are for. It seems like some of them don't make any difference to the sound. Could you give me some information about this? Thanks again.
I think only 2 of the 5 (pickup compensation, boost) are used. The other 3 (treble, bass mix) aren't. If you flip the guitar around and look at the back of the PCB you'll see the labels.
The "comp" trimpot adjusts the volume of the 2 & 4 positions, allowing you to match the output of the fully humbucking positions. (Personally I turn that one down- I want them quieter.)
The "boost" trimpot adjusts the level of the push/push boost.
The other 3 don't apply- they're meant for a piezo pickup, which this guitar doesn't have.
Thank you very much for your reply. I was actually wondering if the three glued potentiometers were broken, because I couldn’t hear any difference when turning them.”
My guess is that Music Man used a common PCB for multiple guitars at that point in time. The Luke doesn't have a piezo, and that section isn't wired up. (There are more connections on the right side of the PCB as you can see.)