I'm surprised that dela didn't mention that the Greg Lake/Entwistle Pirate bass has a graphite neck! It looks like one of the really early ones with the crystalline graphite finish (for those who like graphite trivia, it was the crystals, then checkerboard weave, then irregular polygons.
Graphite or wood, cutting a chunk of the neck structure shouldn't matter too much - the pickup routings are done that same way and it's stabilized on both sides being glued to the body wings.
The hum cancelling coil doesn't need to be near the strings to work. The canceller is a wound bobbin like a pickup but with no magnets, so it can't hear metallic strings. It will hear any radiated electromagnetic fields which is what was causing the hum in your pickups. Flip that signal over, subtract it from the magnetic pickup output and you have string sound minus noise. Awesome. It would probably work better if in the same 3-D orientation as the pickups, so the normal position in between is optimal but anywhere on the instrument would be fine.
There aren't that many instruments out there that have hum cancellers, but they typically were hidden rather than visible. If you've ever seen the original PRS bass, it had 3 pickups on the front and a hum canceller that looked just like a pickup on the back under the bridge area. Also, Fender Elite Strats from the early 1980's had a hum canceller hiding underneath the pickguard between the pickups.
David Fung
