I bought this preamp to substitute Tonepump jr. on my Spector. It took me a lot of measuring and soldering to get the thing working.
The fundamental problem for me was the rigid layout of installation. The grounding was done with quite rigid uninsulated steelish wire soldered to the pot rings touching the pickguard. In addition the ground wire was soldered to the output jack and some pot solder lugs.
As the Spector output jack doesn't go thru a pickguard (as Spector has no pickguard), I had to disassemble the output jack. In addition, the pot layout was not exactly suitable for the holes. So I decided to remove the ground wires to release the parts.
During the assembly, I needed to to fit the assembly to the cavity and holes, and ended up with a couple of lose wires, which should have been professionally soldered but IMO were not (because they just got loose from the soldering lugs due to some bending but no pulling).
I re-soldered the lose wires and installed the preamp. The first test resulted in a very noisy sound. I isolated the problem to the preamp, the volume pot connections to preamp, and the EQ pots, as bypassing the preamp produced nice sound without extra noise.
I could not find the problem with visual inspection, so I re-soldered every wire going from the preamp to the pots, and the problem was gone (except the noise for turning treble to full).
If you don't have the exact layout for the pots and the output jack as shown in the picture, you are probably better of by buying the preamp and the rest separately.
