Cavity shielding/noise reduction

This question is for Teles/Strats, or any guitar with single coils for that matter.
What is the most effective way to shield the pickup and control cavity routes? Seems to me the standard is the foil? And then do you have to solder a wire to the foil and run it to ground, or something...
Looking for the best way to do this, to try and eliminate as much sc noise as possible.
Thanks.

Typically people use copper foil. Usually it is either adhesive backed or glued in place. Copper foil is preferred because you can solder to it. All pieces must be electrically continuous, so you should bridge the pieces with solder. Additionally, all cavities must be connected through some manner. Most people will put a tab of foil on the surface of the body from each of the cavities; when you shield the back of the pickguard, they will be joined.

You can use aluminum foil or aluminum tape, as well, but you will have to get a bit more creative with how you bridge pieces of foil, because you can't solder to it.

Another way to shield is with electrically conducting paint.

Regardless of how you shield, you should connect the shielding to the ground (usually the back of a pot).

Thanks Loc, that's very helpful!

This was a budget guitar I built with scrap wood and used parts. The pickups were cheap and really noisey. After I shielded it I couldn't believe how quiet it was.

http://i334.photobucket.com/albums/m408/apolloguitars/misc/crapster023.jpg

Here is a close-up of all the cavities. They are all connected together with the red wire you can see running from one hole to the next. That is all grounded to the control plate by the tab on shielding at the ends where the palte screws down.

http://i334.photobucket.com/albums/m408/apolloguitars/misc/crapster023x.jpg

I even wrapped the pickup wires where they pass thru the body. Every bit helps.

http://i334.photobucket.com/albums/m408/apolloguitars/misc/crapster024.jpg

Some people say that shielding affects the tone of the guitar. I'm sure it does a bit... but I certainly don't hear it. I'd rather have a quiet guitar.

Nice work, John. I especially like the honeycomb. It gives you plenty of places to temporarily park your chewing gum.

Nice work, John. I especially like the honeycomb. It gives you plenty of places to temporarily park your chewing gum.

Until you put the p/g on.

http://i334.photobucket.com/albums/m408/apolloguitars/misc/crapster022.jpg

Thanks for sharing. Excellent information. This, and the neck cross sections! You are the totally awesome. Who knew that the truss rods were so bowed like that?

I hate to do this because they're a little fanatical and exaggerated, but there's a discussion on guitarnuts that talks about the idea behind shielding. The capacitor string-ground isolation thing hasn't caught on with anyone else though.

Anyway, I have tried foil and paint and let me tell you, the paint is so much easier. Expensive, but that little can goes a very long way. You can even line the holes between the pickup and control cavities by painting it with a cotton swab.

Lindy Fralin mentioned that with foil, there's always a risk that the adhesive comes loose and it can short out the guitar at the worst possible moment. That, and getting a few paper cuts with the copper foil makes you think twice about it. Try the paint.

The capacitor string-ground isolation thing hasn't caught on with anyone else though.


I have no idea the technicalities behind this but from the name I'm interested for sure :).

Guitarnuts' forum seems to be blocked from work though - will check it when I get home :).

For the cap mentioned with regards to guitarnuts.com, it is for situations where the amp isn't properly grounded.

Essentially, you place a .33uF 400V cap between the signal ground and the ground at the jack. This isolates the signal ground from the house ground system and will prevent current spikes due to a better ground (you) being introduced to the circuit, thus preventing you from getting the **** shocked out of you...literally. The mod should reduce the max current down to about 30mA...which would still suck, but hopefully not kill.

One caveat, though, is that the jack itself and the jack cup/whatever you are using to mount your jack with (if it is conductive) will still be on the mains ground...so you can't eliminate this completely.

The capacitor string-ground isolation thing hasn't caught on with anyone else though.

I tried this once on a strat, and it definitely quieted the noise. Problem was, it also lowered the output of my guitar quite a bit!

...Maybe I should have used a different value cap.

Why are some single coil guitars virtially quiet without any shielding?
Were any Fenders or Gibsons shielded? I don't remember seeing any on older guitars...

I am not trying to be obnoxious or against shielding but there have been lote of guitars without it that seem to have no problems. I was wondering if there was a problem that could be solved instead of using shielding to cover the problem?

StewMac sells copper shielding tape with conductive adhesive. You don't have to solder the joints.

Watch out for those little cuts on your fingers. ouch!

Why are some single coil guitars virtially quiet without any shielding?
Were any Fenders or Gibsons shielded? I don't remember seeing any on older guitars...

I am not trying to be obnoxious or against shielding but there have been lote of guitars without it that seem to have no problems. I was wondering if there was a problem that could be solved instead of using shielding to cover the problem?

Gibsons tended to have humbuckers which, by design, filter our the noise. As for shielding in stock Fenders? Yes. The Jazzmaster and Jaguar both had shielding stock.

Additionally, some hum/hiss was always usually tolerated but as electronics become better and better at constantly reducing prices, sound quality is more important to people.

I am slightly unsure about the shielding of the pickguard, there are plenty of examples of the body shielding, and IIRC in one of Ron Kirn's threads he seems to be using a metal sheet shielding technique for behind the pickguard ........ however - a couple of questions re: pickguard shielding, are you supposed to shield the entire back of the pickguard? or just the 'roof' of the routing? and do you have to be careful so as not to affect too badly the thicknes of the guard and leave it uneven when attached to the body .... and how do these factors impact the tape Vs paint choice - can paint be applied more thinly than tape?

personally i am considering using copper paint, and (in order to avoid dripping, overpainting onto the finish) using the shielding paint before I do the finishing, and then filling the routes over the shielding with cotton wool / material in order to not get nitro on the shielding ...

any thoughts on any of the above?

I think about shielding particularly bright and noisy guitars; I've done two in the last 2 years. Sometimes losing that little extra bit of high is not a sin.

I like the idea of the adhesive backed sheet copper, in part because it can be ripped out if you or the next owner feels that way about it.

Thinking about shielded cable for the lead to the jack, and I do like to braid my leads except that with a 3rd (separate ground) lead from the neck pickup, the chase gets mighty tight if you braid too tight. (cloth wiring)

You can simply twist the 2 leads together like old lamp cord, that will give ya all the shielding you need on the wire. and you must connect the copper foil in the 3 cavities by soldering a small wire and run it to the next, then the next, to insure electrical continuity.

Ron Kirn

I remember taking apart a cheap old guitar years ago when I was teaching myself how to do this stuff and someone had coated all of the solder joints and exposed wire with what looked like rubber cement. You could actually peel it off like you can with rubber cement after it dries.

Is this a viable solution or was it someone not knowing what they were doing?

loog: Typically, you shield the entire pickguard. The thickness of even the thickest aluminum tape is still VERY thin (5mil, I think) and it won't make a noticeable difference in the guard thickness.

bossaholic: That was likely to prevent shorts, not shielding. By covering all exposed metal, with something non-conductive, you won't have any sort of shorts to worry about. To properly shield, you want to make what is, essentially, a Faraday cage around the electronics cavities.

the thicker tape w/ conductive adhesive is of a very good quality.

I shielded around pickups (with foil) once and the change in tone was noticeable. Maybe it's OK with paint?
So I only shield the control cavity and it's fine. I also wire it as clean as I can.

On my next guitar I may add an external braided shield to the cables coming from both pups to the control cavity. If I find a mesh wide enough for the two cloth wires coming from the pups (any links wellcome)

My current Tele has the protection cap (http://www.flickr.com/photos/36977023@N03/3413491444/in/set-72157616235313262/). But I separated the signal and the strings ground so only strings/bridge/knobs/plate see the cap before ground, not the signal from the pups.


PS I love that nice knotty body. What's the finish, shellac?

I shielded my two electric guitars and it made a huge difference, especially in my Tele. It was so noisy before and now it's quiet. If it affected the tone I didn't notice. I also potted the pickups, which I would recommend if you're getting ear-piercing microphonic feedback. You boil the pickups in a mix of parafin wax and beeswax in a double boiler. Once again, maybe it affected the tone, maybe not. My guitar still sounds great, so whatever.