I found some pics while looking for something else of a pickup I made a while ago for friend. He has a big hollowbody Gretsch Electromatic and wanted a hot P-90 in the bridge position but didn't really want to mod or rout the guitar. I figured why not just make a P-90 that fits straight into the original Gretsch pickup surround. How hard could that be?
I had a few Gretsch pickups here, so I started by seeing just how different in size they really are. While the P-90 is obviously longer, the width is the same which meant all I had to do was make a P-90 cover that was all the same dimensions except ... not as long.
I cut the ends off a P-90 cover, removed some material on each side of the pole piece holes and then glued the ends back on. I then sanded and polished the cover to hide the glue lines and went about making a new shorter bobbin for it.
The bobbin, like the cover had to be essentially the same size as the original but not as long which meant less room for windings on the ends of each end of the coil. I didn't want to make the bobbin deeper than the original as I wanted the entire pickup, including the magnets to be encased in the cover. This left me with considerably less room which meant, thinner wire to pack more on.
I wound the bobbin with AWG #44 and managed to get just under 10.000 turns on before it was packed. This gave me a very healthy reading of 10.6K which would work just fine.
With the coil wrapped and the lead wires on I set about working out how to mount it to the original surround. The obvious solution was kind of like Gibson did on some P-90 loaded SGs back in the day. Attach a mounting bar to the bottom using the 2 original screw holes in the cover/bobbin so I just cut a piece of aluminium extrusion and drilled the holes to match.
With it mounted in the surround and height adjustment screws and springs in place it was time to install it in the guitar and see what it sounded like.
My big fear was that the very high output bridge pickup would completely overpower the original low output Gretsch neck pickup but with a little bit of balancing they actually played pretty well together, and the mini P-90 sounded great both by itself and with the neck pickup, and no modifications at all to the original guitar. Job done.