Shielding

[Donny19]

Hey all,

I ordered my first kit (a GTL-1) and have just finished the painting process. I'm about to start the wiring but was wondering if the shielding tape should be put in before or after the wires are soldered?

This is my first build and I know it's not going to come out perfect but it has proven to be a great lockdown project. Any tips on the best copper shielding methods for a newbie would be much appreciated.

Cheers

[Donny19]

And if the shielding tape goes first, how do feed the wires through? Sorry I know this sounds dumb but I don't want to make a preventable mistake and screw up my whole build lol

[Simon Barden]

It's easier to apply it after painting/finishing and before you install any wiring/pickups etc.

Cover the inside of the cavities and the underside of the pickguard. On a Tele, you'll need to run some grounding wire from the main control cavity to the neck pickup rout. I normally just copper tape the ends down.

You just make holes in the copper tape to push the wires through. You can't help it, but try and keep any holes as small as possible. Run the copper tape for the neck pickup rout over the edge on to the top, so that it can make contact with the tape on the underside of the pickguard. Run the copper tape for the control cavity up over the edge on the two ends of the cavity so that it makes contact with the metal control plate (but cut it so that it's all hidden by the control plate.

Run the copper tape up over the front and rear edges of the bridge pickup rout so that it makes contact with the bridge plate. You'll be running a ground wire for the bridge, so the bridge will ground the pickup cavity copper. Or you can run a ground wire from the control cavity to the bridge pickup cavity, copper tape it down, and let the copper ground the bridge.

Always run the copper tape right up to the top of the cavities, and slightly over the top where you can without it showing. You want to make as complete a copper/metal enclosure as you can with the smallest of holes in it.

Use a multimeter to test for continuity of copper tape grounding once finished. And check that the control plate makes ground continuity with the bridge plate.

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.

[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.