Shielding?

[waltdogg]

I'm going to shield the control cavity of my double cutaway Les Paul. The P-90s are a bit noisy sometimes. I was going to put an aluminum shield on the underside of the pickguard and go with copper tape for the control cavity and underside of the control cavity cover plate. Anything I need to know? I was also looking at shielding paint, its more expensive than tape but looks easier to use. Are the results any better or different?

[oscillateur]

I've only used copper tape (on a Jaguar guitar and Mustang bass) and it worked fine. Properly plan the size/shape of the bits of copper tape you use before to be sure that you don't have excess bits all over the place. Make sure that you have a little bit going over the top the cavities so that contact will be made with the pickguard, too.

Here's a pic I took when shielding the Mustang, for reference (I did the Jaguar first and it was much more messy ) :

IMG_0678.JPG (100.65 KiB) Viewed 4063 times

[waltdogg]

Thanks! That looks pretty clean btw.

I hadn't given shielding my pickup cavities any thought because:

1. the pickguard doesn't completely cover the cavities so some shielding tape might be exposed to see... don't want that

2. the pickups mount to the body so they fit very snugly in their cavities, might scrape against the sides of pickups making height adjustment difficult

3. the pickups have a braided ground on the outside of the lead, do I run the risk of shorting the ground with the copper tape?

Seeing those little tongues that you made I could totally hide those under the pickguard and put copper tape on the bottom of my pickguard instead of aluminum shielding.

[repoman]

Not sure if this is true or hogwash but I read copper and aluminum shield different radio frequencies against hum, if you build the 'cage' out of two different things it won't really be a complete cage around the stuff in them.

[UglyCasanova]

Tape is messy, but it works. My strat gets no interference after I shielded it.

[waltdogg]

repoman. That's why I asked.

I did some googling and it sounds like no amount of shielding short of a copper pickguard (a la Skully's woodbody JM or a Mascis JM) will reduce noise in a P90 guitar. Can anyone comfirm this? IME I setup my friends Squier Mascis JM and between the copper guard and shielding paint under the pickups it was relatively quiet for a P90 equipped guitar. I wasn't really paying attention when I handed off my LP Special to my friend to A/B the P90 tones between my guitar and his so I don't remember if the Mascis was quieter.

[skullservant]

When I shielded the Jazzmaster it cut the hum drastically but didn't eliminate it. Played out and loud with the Jazzmaster yesterday and you could hear the hum, but like I said it was loads better than before

[oscillateur]

Yeah, same for my Mustang bass. There's still a tiny bit of hum/noise but far less than before. It went from annoying to barely noticeable.

[digi2t]

Copper shielding is fine. It's not that hard to work with, and is every bit as good as the paint. Even better I say.

One thing to keep in mind; don't forget to solder any tape joints, and a small wire to ground from the shielding itself, if there's no continuity to ground available. The copper foil is an adhesive tape, and as such, there's no guarantee of continuity between the different pieces of foil due to the adhesive glue sitting between them. Melting a dot of solder between the joints at various places (doesn't need to be the entire length of the joint) ensure continuity over the entire shield. The shield should ultimately have continuity to ground, either by contact with the body of the jack, or a physical wire. After all, what you're constructing is a Faraday cage, to isolate the outside noise, from the inside noise (think shielded cable).

It's for this reason that I will never use aluminium tape, or shielding paint for that matter, for shielding guitar cavities. If I can't solder to it to ensure continuity over the entire area, it's out for me. A DMM, or simple continuity meter is the best tool for ensuring good shielding. Just place one probe anywhere on the shielding, and probe around the cavity at several different points. If there's continuity everywhere, you're golden. If not, then examine that section, and why it's not connecting to the rest of the "cage".

Don't forget the cover too. Take a Les Paul type cavity, ensure that there are tabs of copper foil, especially where the cover screw holes are located, that will contact the copper foil on the cover. This will help close the cage when the cover is on.

[waltdogg]

When I shielded the Jazzmaster it cut the hum drastically but didn't eliminate it. Played out and loud with the Jazzmaster yesterday and you could hear the hum, but like I said it was loads better than before

Okay good to know as your JM has the Mascis P90s in.

Yeah, same for my Mustang bass. There's still a tiny bit of hum/noise but far less than before. It went from annoying to barely noticeable.

Audible change is good.

Copper shielding is fine. It's not that hard to work with, and is every bit as good as the paint. Even better I say.

One thing to keep in mind; don't forget to solder any tape joints, and a small wire to ground from the shielding itself, if there's no continuity to ground available. The copper foil is an adhesive tape, and as such, there's no guarantee of continuity between the different pieces of foil due to the adhesive glue sitting between them. Melting a dot of solder between the joints at various places (doesn't need to be the entire length of the joint) ensure continuity over the entire shield. The shield should ultimately have continuity to ground, either by contact with the body of the jack, or a physical wire. After all, what you're constructing is a Faraday cage, to isolate the outside noise, from the inside noise (think shielded cable).

It's for this reason that I will never use aluminium tape, or shielding paint for that matter, for shielding guitar cavities. If I can't solder to it to ensure continuity over the entire area, it's out for me. A DMM, or simple continuity meter is the best tool for ensuring good shielding. Just place one probe anywhere on the shielding, and probe around the cavity at several different points. If there's continuity everywhere, you're golden. If not, then examine that section, and why it's not connecting to the rest of the "cage".

Don't forget the cover too. Take a Les Paul type cavity, ensure that there are tabs of copper foil, especially where the cover screw holes are located, that will contact the copper foil on the cover. This will help close the cage when the cover is on.

I was wondering about needing to solder. I'll keep that in mind. Yeah I'm trying to cover the entire backs of my control cavity cover and pickguard.

Can anyone tell me if the ground braid on my pickup leads could short to ground on the copper tape if I were to shield my pickup cavities?

[digi2t]

Can anyone tell me if the ground braid on my pickup leads could short to ground on the copper tape if I were to shield my pickup cavities?

Wouldn't be a big deal. They're all part of the ground plane.

[waltdogg]

Can anyone tell me if the ground braid on my pickup leads could short to ground on the copper tape if I were to shield my pickup cavities?

Wouldn't be a big deal. They're all part of the ground plane.

Common ground and all that?

[repoman]

May not be a bad idea to solder copper foil joints, but the adhesive is conductive. I have never had to solder the joints of it and it seems to work fine that way.

[digi2t]

May not be a bad idea to solder copper foil joints, but the adhesive is conductive. I have never had to solder the joints of it and it seems to work fine that way.

Just be careful with that. Not all copper foil tapes sport the conductive adhesive. Always check with a continuity test to be sure.

[waltdogg]

I'll be sure to. Thanks!