[quote name='Hamster' post='31099' date='Jul 13 2007, 09:37 AM']Most of a case of carefully de-soldering and then re-soldering, but yes its simple.  When you say circuit, do you mean the active bass circuit, or just the wiring on a passive bass? 
 
There are quite a few options out there - what sound are you looking for?  
 
Hamster[/quote]Sorry, yes the active circuit, will it make any difference keeping the old circuit board in, or will a new board improve the overall sound of the new pups. 
I'm looking for a growly rumble mainly for rock. Thats the best i can describe the sound hope it's not to technical for you