I've been looking at a review of the Effectrode Firebottle on gilmourish.com.
It has a switch which moves the resonant peak of the sound down by 2khz or 4khz.
I really love the change in sound, you can still tell they are single coils, but with more balls.
Does anyone know of a pedal on here which moves the resonant peak like this.
The Seymour Duncan Pickup Booster (schematic) has a resonance switch that puts a 1n or 3n3 (or no cap) between Q1 base and ground. This moves the resonant peak lower. Combined with the subsequent boost, it lets a single coil pickup mimic a humbucker (still hums though).
I don't know if that's what the Firebottle uses, as I'm not familiar with that pedal. But this trick works pretty well, as long as the pedal is first in the chain. If there are any active devices between the pickup and the cap to ground, it won't work.
You could just as easily add a similar switch to your guitar if you wanted to.