I just bought a used Epiphone Non-Reverse Thunderbird bass off eBay. I like it fine, but the sound of it is strange. It's got a set of P-bass type pickups in the neck position and a J-bass pickup in the bridge position. I would think that would make a pretty solid-sounding setup, but it has an out-of-phase, chorusy sound no matter how i tweak the volume and tone knobs, and through different amps as well. Could the wiring have been messed up somehow? Crappy quality pickups? Suggestions appreciated.