I have a 1996 Hamer USA Daytona (cool guitar BTW!), which from the factory came with 3 Seymour Duncan Alnico Pro staggered single coils. I have installed a Seymour Duncan Lil' Screamin' Demon single coil sized humbucker in the bridge position.
With the factory wiring, positions 2 and 4 on the 5-way switch were hum cancelling as I believe the middle pickup is RWRP. Now that I have installed the Lil' Screamin' Demon, position 2 (bridge and middle pickups) is no longer hum cancelling, but position 4 (middle and neck pickups) still is. It seems that maybe position 2 should be hum cancelling as well. Is there a fix for this?
Humfortunately, what you describe is in accordance with electrical theory.
When you had all singles, with the middle being RWRP, the + hum from the bridge cancelled with the - hum from the middle, making no hum. Now the bridge is a humbucker, and cancells its own hum by itself, hence it has no hum left to cancel with the - hum from the middle pup.
A solution is to install a coil cut switch on the humbucker, to optionally select just the coil which can cancel with the middle in combination. It also provides another sound to the bridge, giving you single coil and humbucker options.
This could be on a push pull, as part of a pot, or as a seperate toggle
If a toggle, there could be more tricks with this switch. It could be a three position on-off-on, to force the bridge pup on whatever the postion of the 5 way, in either of two single coil modes. Hence you could make Neck/Bridge or Middle/Bridge combinations, selecting the right bridge single coil to best cancel hum. Or even, in position 4, have all three pups on (bridge as single coil)
ps Heres another idea. If the main slector switch is the same as a standard Strat 5-way, and if the humbucker is 4 conductor, it should be possible to use half the switch to make position 2 automatically bridge single coil + middle, which would be (close to) humcancelling. Other positions unaffected. No new parts would be needed, but rewiring would be required.
pps also assuming a standard Strat switch, a push/pull pot, or two-position toggle could be persuaded to offer the following when activated:
I have a custom pickguard that has only the bottom two potentiometer holes drilled. The upper pot will be a master volume and the lower pot will be a master tone.
That should provide all of the main sounds that I like, and all will be accessible via the 5-way....won't have to mess with switches, push/pulls, etc.
I do have a couple questions:
Do you know if using the red & white wires (black as hot) for the coil tap on the SD Lil' Screamin' Demon will tap the correct coil to cancel hum with my RWRP middle SC?
Is it normal to use a 250K volume pot with a mini-humbucker like the Lil' Screamin' Demon? I was originally planning on using a 400K (middle of the road), but, surprisingly, I think the 250K seems bright enough....and I generally prefer a brighter sound. I'm guessing this is because the Strat single coil position is so close to the bridge....there is just a lot of inherent twang/high end in that position. I'm gonna stick with 250K for the tone pot.
I dont know of a sure way to predict which coil will cancel hum with your middle pup, particularly if they are by different makers. You'll probably need to rig up a trial and error test, to determine correct phasing for sound, and for hum cancelling. One of the Hb coils, one way round or another will give you both (four possibilities), in combination with the middle. You can narrow it down a bit with the 'screwdrver pull off test', but guesswork is just as good, as long as you figure it out before you do your neat soldering job.
As for pot values, I dont know what is normal with that pup, but whatever you prefer is best for you.