Shielding questions

[jkemmery]

OK, I have a couple of questions regarding shielding and grounding (of the shielding).

First, is it absolutely necessary to ground the sheilding? I understand it's a good "best practice", but it seems that if left ungrounded, it would still effectively shield RFI or EMI (Radio Frequency Interference, ElectroMagnetic Interference). I'm no electrical engineer (as many of you have probably already figured out ... ) so I was wondering what the benefits of doing so vs. the potential pitfalls of sheilding your grounding might be.

Second, has anyone ever tried to use aluminum or chrome spray paint as a sheilding? Since it's probably overall non-conductive, it would be impossible to ground .... (hence the 2 questions go hand-in-hand) But I was wondering wether or not it would be completely useless to try. Thanks.

[sumgai]

jk,

That part about not being an engineer....... we'll just let that one slide under the sofa, OK?

The only difference between an antenna and a shield is that the former collects signals from the air in order to amplify them and make them useful, and the latter collects signals from the air, then grounds them so that we don't have to deal with them. While your ungrounded shield may not add much noise to your signal, it certainly won't reduce the noise at all, not even 1%. 'Nuff said.

Chrome and aluminum are both conductors of electricity (though not the best conductors, by far), so they both would serve as shielding materials. The difficulty might be in applying those materials to the guitar's body. Also, aluminum is notorious for being difficult to solder (and not just the foil, boys and girls), and chrome is probably worse. Mechanical connections are the usual way to conduct electron flow (current) through them.

And for the record, chromium becomes a liquid at something like 1900°F, so any room-temperature paint you see of this stuff will have only a smattering of microscopic pieces mixed within a solution of other materials. Be aware that those other materials may not be electrically conductive, thus rendering your chrome paint job very much less than effective. (For shielding purposes. It might look pretty nifty, though. )

HTH


sumgai

[echobase2002]

1) In order for a shield to work, it needs to give the interference a place to go other than your guitar signal.

2) Conductive paint is available in one particular guitar repair catalog. I'm not sure about the policies for naming specific businesses in the forum, so maybe you should search the web for the words stew and mac

[jkemmery]

Alright, thanks for the lesson ...

I have seen the Stew Mac conductive paint. It's freaking expensive, as far as paint goes, something like 30 bucks a pint. That's why I was looking for an alternative. I kind of figured the aluminum stuff wouldn't be conductive, hence the grounding question. I did kind of figure a metallic substance would block RFI, kind of the way your cell phone won't work in a Wal-Mart. But then again, the metal of the building is grounded ...

[UnklMickey]

echobase2002 said:

...I'm not sure about the policies for naming specific businesses in the forum, so maybe you should search the web for the words stew and mac

We're not aholes about that sort of stuff, unlike some other forums.

If you are trying to advertise / sell something there's a place for that. If you are trying to help someone find a source for something, just name it. No problems.

If you are naming a specific business because you have had problems with them, stick to the facts. That prevents liability.

btw, stewmac is one of the links on the links-page thread.


cheers,

Unk

[ccso8462]

I used the copper foil from stew-mac on my MIM Tele and a Strat copy. It wasn't all that expensive and it's better than paint or aluminum. There's still enough to do a couple more axes. Fairly easy to use and solders very well. Watch the edges, they're sharp!

Carl

[dsrb]

hmm

I've tried once to shield my squier strat, but i dont hear any difference. Now i read this post and i have been wondering.. i just glued the alluminium foil to the pickguard and body cavities. Is this the problem?

(sorry about my english, i'm portuguese =) )

[michaelcbell]

In the words of Adam Savage (host of TV's Mythbusters) "Well, there's your problem." In order for shielding to work correctly, all the pieces of foil need to connect to each other and the shielding has to be grounded, or connected to the ring terminal on your output jack.

[dsrb]

"all the pieces of foil need to connect to each other and the shielding has to be grounded, or connected to the ring terminal on your output jack. "

forgive my ignorance lol, how can i ground the shielding?

[michaelcbell]

well, there are a few ways, but the most common is to sandwich a metal ring lug with a wire connected to it in between the pickguard and a pot. (take the pot off, put the ring over it and re-attach. Then you can connect the wire to the jack (ring terminal). Beware of ground loops (read this: )

[UnklMickey]

The foil on the back of the pickguard might already be connected to the ground. Most stock wirings have the ground being made at the back of the volume pot. If the bushing of the pot is touching the foil, there will be a connection. This is even more likely, if a metal washer is used between the pot and the back side of the pickguard.

The foil in the cavity is another story. Unless it comes up over the edge of the body, and gets sandwiched between the body and the foil on the back of the pickguard, it probably isn't connected to anything.

[dsrb]

hmm.. so.. I need to make contact between all pieces of foil and them must be grounded right? What about the electronics, wires, etc? I didn't work on that part. Will i feel any difference or substancial difference?

[michaelcbell]

the indivudual components (switches, pots, etc.) should be grounded, but only at one location (to avoid ground loops) As for how much it'll help, try it and let us know

[steveblue]

There is a new company that received alot of press at NAMM and in recent releases called axeguardz.com that makes a shielded pick guard ($55). They also sell a conductive paint ($19) for the cavity. I looked around but haven't seen any reviews or people who have used it. It is all quite new. Anyone heard of any body who has tried it?

-steveblue

[crazymanandy]

I read that a guy over at the TDPRI forum bought one and said it worked great.

Though, if you do a good shielding job in the first place, I think this might be a little overboard. But I dunno.

CMA

[UnklMickey]

Hi steveblue,

Welcome to GuitarNuts2.

I had to check out the site to see for myself. $19 seemed very pricey for carbon paint, unless it was a very generous quantity, and way cheap for silver, unless it was an extremely small quantity. Turns out it is for copper paint. I really don't know how copper will hold up over time, it it will oxidize and become less conductive. I have never used anything but carbon or silver. I couldn't tell from the info on the site, but it looks like a fairly small quantity. No bargain, but not terribly overpriced either.

[john50]

Hi - just reading through and thought I'd add that Bill Callaham does a very thin aluminium pickguard shield drilled for 8 or 11 hole for $15. I've got a couple and they're great. Find him at www.callahamguitars.com/

Also, a guy on ebay in the UK is doing a metre x 30cm adhesive copper foil for £8.99 ($18 plus postage). stevent1358

J