Noisey humbucker

Stevepage

I just swapped an original Carbon pickup in my 7 string for a Dimarzio D Sonic.

I've wired the Red to the pickup selector, green and bare to the ground and the white and black to the coil split switch.

According to Dimarzio, this is correct but I find that it's quite noisey. 

It's not as noisey as the single coil, but the original neck pickup is perfect. 

Any ideas of the issue? The cavity is shielded nicely and the pickup sounds fine but it's quite annoying I'm picking up Hum whilst the neck humbucker isn't.

ICBM

Does the hum change depending on whether you’re touching the strings or any other metal parts in the guitar, or change as you move the guitar around?

Stevepage

It's changes when moving. I had to use a noise gate just to be able to play plugged in

ICBM

If it changes when moving it's electromagnetic noise being picked up by the coils rather than lack of shielding.

So the possibilities are:

The pickup was wired wrongly at the factory and is out of phase with itself, hence amplifying rather than cancelling hum. I've come across this just once, and not with a DiMarzio, and in any case you would notice the sound being very odd - quiet, nasal and thin.

There's a short somewhere and it's acting as a single coil all the time - but then you would notice no difference using the coil split switch.

The coils are so mismatched that the hum cancellation isn't very effective. Not sure this is likely with a stock DiMarzio, although there are some pickups on the market with very unequal coils.

I think that's it...

Stevepage

Think I may have sussed it. I added a wire from the back of the pot to another ground point. Must have been a break in the wire somewhere

Funkfingers

ICBM said:

The coils are so mismatched that the hum cancellation isn't very effective. Not sure this is likely with a stock DiMarzio.

It could be with a DP163 Bluesbucker. Screw coil is c. 8k, stud coil is c. 4k.