I am currently using the scpb-2 as a pup upgrade on my '78 Musicmaster bass. It's a good upgrade but I thought an scpb-3 would be still better because of the larger pole pieces. But when I put it in, the output was pitiful compared to the scpb-2. Can't really use the scpb-3 pup. I had my GK 400RB maxed and output still weak. I double checked my connections and they look fine. I took it out and put the scpb-2 back in. Why the big difference? I thought the scpb-3 would have better output than it demonstrated. What is up with that? Should I try again? Bob