So, I followed the diagram for my Spector pre-amp. I've transplanted it into a formerly passive P-bass. It shows the purple lead & a ground lead (mine's black, not brown). My purple lead was too short, so I had to extend it with a piece of white wire. Currently the ground lead is on the center connector, as shown in the diagram, and the purple/white lead is on where I think the sleeve would be. Then the battery lead is soldered to the sticky-up pin part. I don't know if this is right? Do I have this wrong? I can't assemble the bass yet to check.