Series/Parallel.....hum?

[Essthreetee]

Pulled out messed up and pieced back together pre amp...went passive, V/V/T...but also added a P/S switch in front. All is good, everything works, but there is a BIG BUZZ when it is in Series and the Tone is wide open. Other than that, it is dead quiet.

Any ideas?

 

[Jazz Ad]

On some pickups, the shielding is wired to the ground cable.
This is all good in parallel but not in series because then the signal goes through the shielding, adding buzz instead of killing it.
Bartolini is guilty of this on most of their pickups.
If this is what happens to you, the cure is to separate ground and shielding at the pickup and run the shield cord separate from the ground of the pickup.

 

[SGD Lutherie]

That's correct. What's happening is that the shield is now hot, and you get the hum.

What kind of pickups are they?

 

[Essthreetee]

They are the Ibanez version of the Bartolinis....sounds like you hit the nail on the head. Strike another one up for LEARNING.

Thanks for the quick replies.