I put some Bartolini X6's in my Yamaha TRB6p and now, some very weird stuff. The knobs are Volume, pickup selector, bass, treble, mid (or at least I thought it was mids, it's the narrow, skinny one) and then the piezo flip switch. They all used to work as mentioned above. Now, if I rotate the mid knob to the left and select the neck pickup, I get 0 volume out of the bass. If I rotate it towards the bridge (opposite way) I get a VERY growly sound. I already tried unplugging the bridge pickup to make sure the neck pickup works, and it does, so that's not the problem. But at the same time, if I keep the mid knob at center and select the neck pickup, I get decreased volume and a VERY tame sound. Not the boomy neck sound most basses give off. Could changing the pickups have changed the effectiveness of the knobs? Should I just send it to a guitar tech? So I'm a bit confused. Can you help?