Shielding; how necessary is it?

[ragamuffin]

So I've put together a couple guitar and never used shielding. Hum is basically a non-issue at home (I barely get any), but it can get noisy sometimes when I play out or at a friends place, particularly on my p90 guitar.

How necessary do you guys find it to shield a jazzmaster style guitar? What's the easiest "good" way to do it?

[JSett]

I do it as a matter of course on every guitar I rebuild. Copper tape (with conductive adhesive) is my go-to. Easy-ish and works a treat if you do it right.

Grab a beer and take half an hour of your life to cut it neatly and make it good and it's worth the effort.

[Embenny]

Necessity is in the eye of the beholder. Without shielding, the guitar can and will pickup HF interference from any nearby noise sources. How many noise sources you encounter, and how much you care about the noise is variable.

I have a low tolerance for noise, I like to compare it to how people would react if a piano or trumpet made a constant droning noise while playing - not sure why guitarists tolerate it more than other musicians would.

I shield all my guitars. The easiest and cheapest way is with copper tape. The one I use is the Elk brand from Amazon:



I paid something like $12 for enough tape to cover multiple guitars. The adhesive is electrically conductive, and when I'm done I can touch any two points in the cavity or on the back of the pickguard with my multimeter and find good continuity. You just have to make sure that each piece overlaps with the next, and that they make contact with either a ground wire or the casing of a pot. I usually do that by leaving small overhangs that reach up from the cavity onto the top of the guitar, so that there are multiple points where the cavity's shielding makes contact with the back of the pickguard, and then I apply shielding to the back of the guard if It's missing. That shielding is in contact with the casing of each pot, and the pots are all grounded to the output jack, so the whole thing forms a Faraday cage.

Takes about an hour or so to shield a Fender style guitar, and in my noisy environment at home, the difference is clear and instant. It's so easy, cheap and effective that I don't really understand why I wouldn't instantly do it to any guitar I have on the bench.

[JackFawkes]

I'm lazy, so I'm just gonna requote my opinion that I wrote in a previous similar thread:

I feel like I've probably spent several hundred hours over the past 3-4 years reading about and testing hum and buzz reduction in guitars, because I absolutely loath extraneous noise through my pedals and amps... it drives me crazy!

That said, I've come to the conclusion that shielding is only worth the effort if you use coated strings.
Shielding only reduces buzz, not hum; but buzz mostly disappears when you touch your (uncoated) strings (as long as they're grounded the way they should be). I've only tested a handful of examples, but in those few before and after comparisons, my experience has been that:
On an unshielded guitar, touching uncoated strings that are properly grounded, buzz is reduced by about 95%
Shielding that same guitar brings buzz down to about 80% when you're not touching the strings... touching them takes it down to the same 95% as the unshielded guitar.
So yeah, if you're using coated strings, definitely shield to get that 80% buzz reduction; but if you use uncoated strings, just playing the guitar (touching the strings) quiets the buzz down more than shielding does anyways... at least in my experiments.

Also, I absolutely agree with Sweetfinger; if you are going to shield, MG Chemicals super shield sprays are excellent. I've experimented with both the Carbon (838AR) and the Nickel (841AR), and they both worked equally amazingly well. I haven't experimented with their Silver (842AR) or Silver Coated Copper (843AR), but honestly I don't think they'd work any better than the Carbon or Nickel for our buzz shielding purposes.
However! The paints are fairly permanent. If you'd ever want to remove the shielding and restore the guitar to its previous state, use tubs or foil... it'd probably take a lot of sanding to remove the MG Chemicals spray.

If you're using single coils (and you're touching uncoated, properly grounded strings) the rest of the noise you're hearing is hum, which shielding does literally nothing for... buzz and hum sound similarly awful, but are two different phenomena which can only be dealt with by two different approaches.

Anyway, those are just some anecdotal data points from just one person who intolerably hates both buzz and hum.

Jack

P.S.: To reduce/remove hum, use only humbucking pickups or quality "noiseless" single-coil pickups.

[Larry Mal]

P.S.: To reduce/remove hum, use only humbucking pickups or quality "noiseless" single-coil pickups.

I do both. I can't imagine not shielding a guitar. Even if I was willing to live with hum, I still would not want to hear any RFI or EFI interference.

[Embenny]

You're right about much but not all of the issue regarding buzz.

Human beings are filled with saltwater, and are okay-ish electrical conductors. When you hold a guitar, you act like an antenna, picking up extra HF noise and transmitting it to the guitar's electronics.

When you ground yourself via the guitar's hardware or strings, you stop acting as an antenna, and the buzz is dramatically reduced. But all you're doing is eliminating yourself as a source of extra noise. You're not doing anything to block HF noise from elsewhere in the environment (the very same noise you were amplifying as an antenna).

Shielding reduces this noise when your hands are off the strings, absolutely. But it also reduces the HF buzz that would have been picked up without the aid of a human antenna, which is what an unshielded guitar still picks up while you're grounded playing it.

The higher gain you use, the more prominent any noise at the source will become, and it depends completely on the electrical environment you're in. If you're somewhere that doesn't have a noise problem and you're playing clean, you won't notice that reduction in noise.

But if you are somewhere with noisy fluorescent lights and are playing with high gain, it doesn't matter that your hands are on the strings, because the guitar is picking that noise up without the aid of its human antenna.

I use high gain a fair bit and I have a noisy environment. Shielding makes a huge difference, even compared to having my hands on the strings. I use the same patch on my AxeFX to test for noise, so that the gain level and EQ are constant. Huge difference with the shielding. It's common for any stock humbucker Gibson I bring home to buzz like crazy on that patch until I get some shielding in there, then it's just about silent. I've done A/B comparisons on enough guitars to be completely confident in that.

But that's an environment-dependent thing. If you're playing somewhere without a source of HF noise, it won't make a difference.

I agree that you have to keep buzz and hum straight. Hum (50/60 Hz) is far too low frequency to be shielded by anything other than a thick mu metal box, so humbucking pickups are the only solution there. But all those Gibsons that have passed through here in the last few years were HH guitars, and all of them buzzed like crazy in comparison to my shielded Fenders with Kinmans.

[DeathJag]

I use copper tape, but I didn't on the Deathjag. That guitar is the quietest damn guitar I've ever held. Even on single coil mode it is almost completely silent. I don't understand it! It has an aluminum pickguard, but the others have that piece of metal underneath their guards that should shield it just as well. I am not going to have to shield that guitar, somehow.

So you fellas are saying even with noiseless pickups, there is still buzz when you're not touching the strings? (Not a hum haha!)

[ragamuffin]

Thanks guys, I guess I'll give shielding a try this time!

[GilmourD]

This is the guide I'm going to be following with my upcoming Jazzmaster build.

https://www.youtube.com/watch?v=-mLBo4y9t8Y

[Larry Mal]

That's how you do it.

[ThePearDream]

Yeah, shielding may or may not be necessary for you. It's the right way to do things though, imo. You might move to somewhere with noisier wiring, you might sell it, you might give it to a niece or nephew who play it in a band, whatever. Shield it now and it'll be done. I've used the prepared paints, made my own paint using graphite powder, and used foil. They'll all work if you take care to do a good job (3 coats of the shielding paint). Foil is fast and easy and cleaner though.

Also consider getting some shielded wire. It may not be vintage accurate , but it works great. I generally shield all of my cavities and pickguards, and use shielded wire whenever possible.

[GilmourD]

Also consider getting some shielded wire. It may not be vintage accurate , but it works great. I generally shield all of my cavities and pickguards, and use shielded wire whenever possible.

Good point on the shielded wire. Now, one thing to note, though. Something I learned from working on tube amps is to only ground one end of the shield in the wire to prevent ground loops, which would just end up inducing more noise.

Also, with regards to anodized pickguards and their effects on shielding, here's a comparison from Mike "Puisheen" Adams. I cued the video up right to the point where he's talking about it.

https://youtu.be/uT2sKbdZh50?t=627

[Larry Mal]

Yes, aluminum pickguards make a tremendous difference, and are much better than a plastic pickguard with copper tape. Over the years, I've found that by using full cavity shielding (copper tape or paint, but I don't like the carbon kind anymore) along with noiseless pickups like Kinman, and an aluminum pick guard, I can have a virtually noise and hum free guitar.

That was a really tortured sentence but you get the point.

If that sounds like a lot and probably expensive, it is, but over the years I've found that if I don't just do the effort right the first time I end up not being happy and just have to do it again.

Honestly, the fact that we are discussing shielding in 2023 is just because the guitar industry has been allowed to be as lazy as shit. Fender used to take shielding very seriously, and so did Gibson. Over the years they've been allowed to cut corners and since they are the industry leaders everyone else has followed suit.

Like Mike says, if you somehow were able to play a violin and it had the noise that electric guitars do, you'd never find that acceptable.

[madlovepickups]

It is also possible to over shield. By providing multiple paths to ground from the same point you can introduce ground loops, more of an issue with active electronics but it’s worth making sure that grounded components only have a single path to ground either through your shielding or through a wire, not both.

With anodised guards the anodized surface is not conductive so sanding/scratching away some of the area under grounded components and/or using star washers is a good idea. If you look at vintage fender jazzmaster wiring you’ll see that there’s no wire to the jack shield as it uses the guard for all paths to ground.

Shielding is only effective if it has continuity with the jack shield. I’ve seen a number of guitars which have conductive paint in all the cavities but then no connection to the jack shield so it’s worth checking continuity between all grounded components/shield points and the jack sleeve.

[Larry Mal]

It is also possible to over shield. By providing multiple paths to ground from the same point you can introduce ground loops, more of an issue with active electronics but it’s worth making sure that grounded components only have a single path to ground either through your shielding or through a wire, not both.

With anodised guards the anodized surface is not conductive so sanding/scratching away some of the area under grounded components and/or using star washers is a good idea. If you look at vintage fender jazzmaster wiring you’ll see that there’s no wire to the jack shield as it uses the guard for all paths to ground.

Shielding is only effective if it has continuity with the jack shield. I’ve seen a number of guitars which have conductive paint in all the cavities but then no connection to the jack shield so it’s worth checking continuity between all grounded components/shield points and the jack sleeve.

Good points. Most of the aluminum pick guards I've seen have bare metal where the knobs connect so as to connect to ground.

And yes, if your shielding doesn't have continuity all the way through then you have added antennas that will pick up even more noise and not shielding.