[quote name='JTUK' post='1112035' date='Feb 2 2011, 09:24 AM']It is the positioning of the pups that contribute so much..esp P-bass, IMO.[/quote]
I'm not convinced by this argument (which seems to be commonly held). I think the position of the pickup mainly affects the amount of low end it generates. The design of the pickup itself seems to have a much greater influence on its character. The difference between the P and Jazz is probably down to the geometry of the coil, for example.
If you don't believe me, listen to a Strat. Three pickups in quite different positions, each one sounding just like a Strat.