ok. i have a schecter c-1 hellraiser w/ fr and it has active humbuckers on it. i was wondering what effect lowing or raising them has on sound.

Active pickups have very weak magnets that aren't affected much by string height. You should put them as close to the strings as you can, without having them interfere with your picking. The output those pickups produce will increase as you move them closer to the strings.
WTLTL 2011
active pickups have an internal preamp that amplifies their signal, thus reducing the need for a strong magnet. They are also more quiet because of the shielding and the less sensitive magnets (which are boosted by the preamp to maintain a healthy volume). So yeah, the battery powers the pre-amp which compensates for the weaker magnets.

I hope I'm making sense
WTLTL 2011
makes perfect sense. so how's about on a les paul? how would raising or lowering them affect the sound?
Depends on the Les Paul, I'll assume you are now talking about passive humbuckers. As you move the pickups closer to the strings, the output will increase and their general sound quality will also increase. However, if you move them too close the magnets might attract the strings, which produces a feedback loop of noise. Basically move the pickups close enough to sound nice, but not so close that the magnets attract the strings.

Also, keep in mind that sometimes neck and bridge pickups have different output levels. So try to arrange them so that they sound about just as loud. My EMG 85 tends to be a bit louder than my EMG 81 so I have the EMG 86 slightly further away from the strings. Same applies for passive pickups.
WTLTL 2011
Last edited by Mark G at Oct 11, 2007,
First set your string height. The closer to the strings the pick-up is, the more output you will get but….if the pick-up is too close the strings, problems can occur with magnetic pull. If the pick ups are too far a way you get a muted muddy sound.

Always check the height of the pickup while fretting the string at the highest (last one at a time) fret.
Measure the distance from the top of the pick-up to the underside of the string.
Adjust so there is between Bridge 2.5mm (0.10"or 1/16) and Neck 3.00mm (0.12" or 3/32" ).

I have a guage I made out of plastic I rest on my pups I use when it touches the string I stop adjusting.