Why do humbuckers' default split coil is usually the slug coil?

[Gstring]

OK Somehow I got a bit confused regarding your suggested improved wiring. So you can just switch the black and the green as I originally said. Of course you do this to both pups. I did not actually say this in my post as I thought it was obvious Otherwise pups would be OOP. Apologies if I somehow confused you to.

[ThreeChordWonder]

Just to add, regular (not RWRP) Seymour Duncan single coils are "south up" polarity, IIRC. The slug coils on SD humbuckers are "north ups".

Therefore, in HSS (or HSH even) configurations, when you coil split and combine with a single coil, you get a hum canceling pair.

Also, you can arrange the wiring on an SD pickup to coil split to the screw coil if you really want to in at least one of two ways:

1. By connecting the black and green wires to each other. The red then becomes your hot, and the white your ground (or maybe the other way around, depending on how the polarities work). When you coil split by grounding the black and green, the green becomes the ground for the screw coil, and the red remains the hot. Since both ends of the slug coil are grounded, the slug coil is rendered ineffective, leaving only the screw coil active via red and green.

2. By arranging the push-pull so that the pickup black wire goes to a common lug. In push the black connects to a wire out from the push lug on the push-pull to the hot wire to your volume pot or selector switch. In pull it disconnects or goes to ground (your choice). You also need to connect the pickup red wire to the other common lug on the other bank on the push-pull. In push it connects to the pickup white wire (also connected to the push-pull, of course), in pull it goes to ground.

[IMENATOR]

Ain't that because the slug poles are the most similar to the poles in a true single coil? I agree with some saying that using the screw coil may be too thin in the brdige humbucker, I also remember some video where someone would split to slug coil in neck and also flip it so the slug coil was closed to the neck and that improved the split tone. Also in my experience if you use a regular SSL-1 in the middle it will be hum cancelling with the slug poles of SD humbuckers.

[ThreeChordWonder]

. Also in my experience if you use a regular SSL-1 in the middle it will be hum cancelling with the slug poles of SD humbuckers.

Yes, and if you happen to have a RWRP pickup as your third pickup, stick in the neck, not the middle like you might on an SSS steup.