Blue wire help for active bass

[NelsonNelson]

I have two J45 pickups by Bill/ Wilde pickups and a 3 band pre. The issue is this is preamp number 2 and I now know the problem is the blue wire that comes from each pickup. They are not ground nor can they just be disconnected as I have tested both options now. I am getting extreme noise from them whenever the treble is boosted and it goes away when the strings are touched. Everything is grounded properly I just need help as to where to solder these blue wires.

[SGD Lutherie]

The blue wires go to ground. They are the pickup's shield and also ground the metal parts.

The black wire is the common return from the pickup's coil, and also goes to ground, unless you are using a preamp with a floating ground like an Audere.

Here's Bill's own diagram, in his own handwriting for a P/J set.

Buzzing when you don't touch the strings is a shielding issue, and/or a ground problem at the amp, usually from the output it's plugged into. Also if you are around light dimmers and other sources of noise, the shielding might not totally get rid of it.