|.How's it sound?
Any two pickups that normally
sound full and rich when combined will yield a thinner, more shrill sound.
Why would you want that? It's great for reggae or funk where you
need a bright sound. Also, this will cut through a lot of effects
or distortion that would otherwise make your tone too muddy.
The other just as noticable effect of an
out of phase combination is that the volume drops. This subtraction/cancellation
is removing part of the signal, so your output is decreased by however
much is removed. In spite of this, a phase switch can produce the
most radical alteration of your tone of anything described on this site.
how many phase switches do you need?
Brian May from Queen has a phase
switch for each pickup on his signature guitar, but this is more for convenience
than necessity. See, phase reversal is a relative thing. If
you reverse the phase of two pickups in use at the same time, you'd just
have them back in phase with one another. As a result, you really
only need one less than the total number of pickups on a guitar.
For example, if you have a standard Les Paul, you only need one phase switch
for the two pickups (unless you're going to throw in coil taps... but that's
a whole other story). Similarly, if you have a Strat, then two phase
switches would be adequate to achieve every possible phase combination.
Remember, if you reverse the phase of two pickups, then they're right back
in phase with one another.
Now, as far as I'm concerned, if you have
a Strat, then you would be perfectly fine to only install one phase switch
for the middle pickup. That's the pickup that is used in combination
with the other two on a stock Stratocaster. If you do a pickup
add-in or a parallel blender to get new,
non-stock combinations, then, yeah, you will get the neck and bridge pickups
by themselves and need another phase switch associated with one of them,
but do you really want to go overboard? Okay, I do a lot on this
site, and even I haven't installed more than one phase switch on a guitar.
Save your time, energy, parts, labor, and control cavity space for more
useful mods. I think there are a few on this site that might work
for you. Start with one phase switch and work from there.