That's a big question, Sam - and it depends on the magnets in the pickup, and the player's touch and string gauge, IME.
Scott Lentz uses Alnico 2's - that's strong magnet, Scott recommends the treble side of the pickups be set at 4/32 on the treble side with the strings fretted at the last fret, and 5/32 on the bass side, measured from the bottom of the string to the top of the polepiece - THEN tweak slightly to taste. Scott says any closer and they'll pull on the strings.
If they were A5 magnets you could put 'em a lot closer. There is a 'sweet spot' - really more of a 'sweet range' for most pickups. I personally find that if you get very far out of the range, you don't get as much as you can from the instrument. In single coils especially, I find that the closer they are to whichever string, the pore pronounced that string is - so closer to the bass side means more bass, further means less, but that's just a generalization.
For Tele pickups, older guys used to tell me that the bass side height determined the "tone" of the pickup, and the treble side determined the attack. To my ears, that's true to a certain extent, but it's more complex than that. To me, within that certain sweet range, the above is true.
I know cats who run their Strat pickups really low - down to the level of the pick guard, a mile away from the strings, and they sound OK when they play - and some sound pretty good with the pickups set like that. I know cats w/ Alnico 5 Tele pickups that put 'em 1/16 away from the strings that sound good too.
I run into issues like if I set the pickups too high, stomp boxes sound funny, especially gain/ distortion stomp boxes. Too low and there's too little output. It's really hard to say, and so much depends on the players touch and gear, string gauge, etc.
Anybody else?
Thanks, Dana O/
Happy fingers typing too quickly. Yes, A5's are stronger, A2's are weaker.Ummm, you got it backwards. Alnico 5 magnets are much stronger than Alnico 2. Alnico 3 is weaker than both of them.
http://www.planetz.com/alnico-magnets-in-depth/