Although I am a guitarist, I avidly watch all of these beautiful custom basses come alive. I, by my own admission, am relatively ignorant when it comes to the instruments electronics. So, could someone possibly explain, without getting carpal tunnel syndrome from excessive typing, what a hum canceller on a bass is for?
 
Thanks,
 
Jonathan

Jonathan; it's not just a bass thing.  Series I and II guitars have them as well.  Here's a quote from a post Mica made earlier:
 
The pickups are single coil in a Series I/II system and require the dummy humcancelling pickup to eliminate the hum that plagues the single coil design. It doesn't pickup anything, it's more like an eraser ... humbuckers have two coils each wrapped around a magnetic core in an opposite direction and the magnetic domains flip or buck. Our humcancelling pickups have only one magnet (more like a single coil on the top with a humcanceller coil on the bottom). So to call them humbuckers is incorrect.

Thanks Dave. I always wondered what the bucker part of humbucker meant.
 
Jonathan