Shielding

[MusicStudent1]

On a Tele, you'll need to run some grounding wire from the main control cavity to the neck pickup rout.

Just beware of guitar signals grounding on the copper tape. It's worth sticking some insulating tape on the bottom and sides of the control cavity to prevent pot and switch lugs touching the bottom/sides. Also the jack cavity is another place where the jack socket signal contact can touch the copper shielding when a jack is inserted.

Simon, thank you for the info. I’ve always wondered the need to connect the shielded neck pickup cavity and the shielded control cavity with a ground wire. Everybody does this nowadays, and no doubt, it’s an accepted practice. But - why?? Why is that necessary?

And to clarify, the insulating tape goes under the potentiometer LUGS only, correct?. It’s pretty obvious that in most pots, the exterior is one big connected metal ground so the pot exterior touching the metal shielding tape is desirable, correct?

[jonwhitear]

Simon, thank you for the info. I’ve always wondered the need to connect the shielded neck pickup cavity and the shielded control cavity with a ground wire. Everybody does this nowadays, and no doubt, it’s an accepted practice. But - why?? Why is that necessary?

And to clarify, the insulating tape goes under the potentiometer LUGS only, correct?. It’s pretty obvious that in most pots, the exterior is one big connected metal ground so the pot exterior touching the metal shielding tape is desirable, correct?

The way I understand it is: electromagnetic waves (EMI) hit your signal wire, and induce a current. That's noise. If you shield the signal wire, the EMI hits the shield and induces a current in that. If the shield is grounded, that current will flow to ground. If not, you effectively get eddy currents in the shield, which themselves can induce a current in the signal wire via capacitance.

With the pots, you do want to ground the case. If your pick guard is shielded (i.e. copper tape on the underneath), the shield will ground the pot where it contacts it. In cases where there isn't a shield to ground the pot, you'll normally see a ground wire soldered to the bottom of the pot.

Cheers,

Jon

[MusicStudent1]

The way I understand it is: electromagnetic waves (EMI) hit your signal wire, and induce a current. That's noise. If you shield the signal wire, the EMI hits the shield and induces a current in that. If the shield is grounded, that current will flow to ground. If not, you effectively get eddy currents in the shield, which themselves can induce a current in the signal wire via capacitance.

With the pots, you do want to ground the case. If your pick guard is shielded (i.e. copper tape on the underneath), the shield will ground the pot where it contacts it. In cases where there isn't a shield to ground the pot, you'll normally see a ground wire soldered to the bottom of the pot.

Cheers,

Jon

Thanks for the reply, Jon. Those explanations make sense. ...eddy currents in the shield?! Ok. I guess I need to get off my lazy butt and run a ground wire from my pickup cavity shielding to the control cavity shielding. The pickup cavity on my bass is shielded but not grounded....maybe next string change....it pretty quiet as is.