Pickup height ???

[doomboomer]

I own three basses and one six string guitar (to mess around with) What should the height of the pickups be, to get the best or most out of 'em? The guitar has a double hum in the bridge and two single coils. One bass has the classic PJ setup, another has two soapbars (bridge/neck) and the third (my 5 string) has two musicman style pickups (b/n) I was told recently that it relly makes a difference if they're set up properly.
HELP!!!

 

[The Big BassMan]

The overall idea is to get the pickup at the right height on both sides to get each string to be a loud as the others. If your G string on a bass sound thin compared to the others lift up the pickup a on that side. I had that with my Stingray.