Just got a nice Hohner B-Bass and clearly I'll have to take off the pickups and put in some new foam. But this got me to wondering just when pickup height becomes too low to function properly. I mean, the guy who sold me the bass played it for years with the pickups between 5mm and 7mm from the strings. That's 3/16ths to over 1/4". So at what height do low pickups seriously start affecting the sound?