So ever since I’ve had my 2015 Gibson Les Paul Special Double-cut, the soapbar P90 pickups have always been very noisy. They were making much more noise than the single coil pickups on my Strat. A lot of that noise would go away when I touched the string or bridge which indicates a ground problem.
My first step was to contact Gibson support to see if something may have been missed or broken on my guitar. They confirmed that only the bridge is grounded and further troubleshooting would need to be done by an authorized technician.
I decided to do an experiment. On Gibson soapbar P90 pickups, the two mounting screws fasten to a metal plate mounted inside the pickup cavity. I ran a wire from one screw on the neck pickup, to one screw on the bridge pickup and then would test by touching the wire to the bridge. This would ground the plates under the pickups to the bridge. Any wouldn’t you know it? The noise issue I was having went away!
So I soldered permanent ground wires to each plate and solder these to the bridge ground wire. Now the noise level is low and doesn’t change when I touch the strings or bridge. Nice job Gibson!
I got the idea to ground the mounting plates from looking at dog-ear P90 pickups out of the guitar. They are typically built with a braided outside wire and this braid is grounded to the baseplate, just like you would on a humbucker.
Now my Gibson Les Paul Special is as quiet as my Strat. There’s always a little noise from the single coil pickups, but I can definitely live with it now.