I recent redid the electronics in my Carvin bass: Bart jazz, MM and NTMB preamp. I am very happy with the results!! I used the bass for a gig last night and it sounded great. I really like the MM pickup the best. I wired it for parallel/single coil/series which is really cool. I mostly use it set at parallel or single coil. But all is not perfect . When the blend pot is centered the B, E, and A strings sound ok, but the D and G strings sound weak, like they are out of phase. Turning a hair to the right or left restores the sound, so it is only on the center detent. This is a new blend pot. I had other problems with the old one, but it was also doing something similar except it was happening at different points on the pot. One thing that I think is relevent is the jazz pickup is actually a bridge jazz that I'm using as a neck pickup. I've always had to reverse wire for this pickup when I've had other preamps in the bass (the stock one, and the aguilar). I think this detail may have something to do with it, but I'm not an expert. Maybe because it is wound to be a bridge pickup, it's not compatible with another bridge pickup? I don't know. This isn't so much of a problem, but I'd like to know if there is a fix...thanks!!