There's a reason why a classic P90, either 'dog ear' or 'soapbar' sounds the way it does ... it's a very specific formula ... if you mess with the wire gauge or the coil shape you end up with something that 'almost' sounds like a P90 ... but is a little 'off'.
Making humbucker sized P90s is a challenging business ... it's really fitting a pint into an eggcup ... and many makers take shortcuts. Firstly, to save time and expense, many makers use a conventional humbucker screw bobbin inside ... of course this simply won't take 10,000 or so turns of 42awg plain enamel wire ... probably only half of that, so they fudge the issue by making the wire they use finer. This instantly makes the resulting pickup much more compressed than a genuine P90. Some makers use the commercially available humbucker sized P90 bobbins you see around ... these too won't take a full load of 42awg wire ... so often you see pickups made with these that have DC resistance of around 6.5 to 7k ... even for the bridge. This is way to light a load for a full on growly soap bar or dog ear (these meter out around 8k at the bridge and 7.6 at the neck).
We laser cut bobbins to our design ... so that our winding machine can be set exactly
the same for winding a HB sized bobbin as it is for one of our Jin-Go or Firewatch full sized P90s. Same turn count, same winding area, same turns per layer ... there is absolutely no difference.
Our latest step to make our humbucker sized P90s indistinguishable from their full sized cousins is to use open top covers exclusively. Yes, we are shortly ditching full nickel covers as anything but a custom option. Very few genuine P90s use anything other than plastic covers ... and of course they are totally transparent to the pickup's magnetic field. After lots of testing we concluded that nickel covers loose some of that high end sparkle ... so out they go. The nickel ring 'covers' we now fit block nothing ... as there's nothing in the middle at all ... that's naked bobbin top you see engraved with our name in the pic!