Side-by-side humbuckers/split coils

[Boneless]

There are a few pickups that look like a single coil but are in truth split coils. (DiMarzio Model Js, or a single row of Wal pickups - actually, IIRC, these pickups have a separate bobbin for each string). I'm not talking about stacked humbuckers (which are really a single coil + a reverse-wound "empty" coil, right?). What is the real challenge in making these pickups? Why don't more people make, say, a side-by-side P90 split coil? Do you really need ceramic magnets (running all the way up to the string, instead of a bar magnet below the coil)?

 

[MidlifeBeginner]

They are usually made with two bobbins. Each bobbin covers two strings.

Magnets could be either alnico pole pieces or a bar magnet(ceramic or alnico) across the bottom.

P90 is an overwound single coil. There isn't really space to put that much winding between strings.

You see side by side spit coils on bass, because we have space to fit the winding between the A and D poles. On guitar pickups, expect to see stacks instead because of the tighter spacing.

Making a split coil takes more manufacturing time than a single coil. There are two bobbins to wind. The construction is also more complex, so you can have a higher failure rate in the factory. So, it is not surprising that a side by side split is more expensive to buy than a single coil.