Re: Humbuckers and bridge pickups. Why?
Some good answers already, I'll try my hand though.
1 - Why might you want a humbucker?
This one is easy. The first thing to note is that a humbucker is, as the name implies, hum free. That means when you're pushing lots of gain through your amplifier, to get a lot of distortion, its way, way less noisy and will feed back less.
The reason this is the case is because if you turn the gain (or distortion, whatever its labelled they mean the same thing) up on your amplifier, this is what you're doing:
Clean Guitar Tone:
Guitar Pickup -----> Gain Stage ----> Preamplifier -----> Power amplifier ----> Speaker.
In this example, the Guitar Pickup outputs sound, the gain stage doesn't do much beyond just being a channel volume control, the Preamplifier SHAPES that sound (It doesn't make it louder, it just shapes it, adding more bass, taking away treble, etc) the poweramplifier then takes that shaped sound, and changes it from a fairly low level signal, into a massive great roaring high level signal, strong enough to drive the speaker.
Thats how a clean guitar sound works.
Now what if we want to add distortion?
Well there's a bunch of ways to do that, you can use a pedal, (either one that IS a distortion stage, or one that boosts the output of the guitar) you can turn the gain up on the amp, you can cut slashes in your speaker cones (Yes people used to do this), or you can even solder a diode/transistor into your guitar cable to make a Fuzz cable.
Now by far the most common way is to increase the gain on the amplifier.
When you do that, this is what happens:
Guitar Pickup -----> Gain stage SET TO BOOST EVERYTHING LIKE HELL ----> Preamplifier WHICH DISTORTS BECAUSE IT CAN'T HANDLE IT -----> Power amplifier (which is probably fine with just making the distorted signal louder) ----> Speaker.
Now in this example, the gain stage isn't just acting like a volume control anymore. Its deliberately overpowering the preamplifier, so that it distorts. Now, if you're boosting things to the extent you have a lot of distortion, you're doing a LOT of boosting.
Now if your signal from the guitar has noise in it, even a little, thats going to get boosted too. And, thanks to the way distortion works, especially at high volumes, your signal will be naturally compressed. The difference between loud and soft will be fairly minimal. The noise created by the pickups will be very, very audible over the rest of the signal.
Thats where humbuckers come in. If you want a lot of distortion, humbuckers have less noise to begin with, so when you crank the gain up on the amp, there's way more headroom before noise becomes a problem. There's also a secondary benefit, which is that humbuckers usually have a higher output, and therefore you can get EVEN MORE distortion, because you START with a higher level signal, and that means any boosting has more effect.
And of course on top of all that, there is the fact that a humbucker has a very broad, thick, natural voice, on account of sensing a wider area of the string, and having way more resistance. Both of these shift the strongest frequencies for the pickup, DOWN slightly. They're less trebly and more bassy. Or, put another way, they've got some balls instead of being shrill.
Continued in post 2....