Hi, I have a Yamaha BB N4 bass. It has a lovely tone but I can never seem to get the output matched across all frequencies. The bottom end is powerful and rich but as I move up the neck (more noticable on the G & D string) the output level seems to weaken. I have used Rotosound and Fender strings. I have tweaked the amp tone (Trace Elliot) with some success but the problem still exists through different amps. Is this a faeture of the pick-ups? Is there something I can do with the setup or wiring to help? Should I consider new pickups? Thanks in anticipation. Flick.