Shielding - effects on tone / resonance

jaymenon

We read so much about thin finished allowing a guitar to resonate better.  And so - with something like a Stratocaster, if you paint the pickup / control cavity with conductive graphite paint (or line it with foil) dies it affect the resonance / tone of the instrument significantly?

I know the stock answer 'any modification will have an effect' - but in real practical terms, will screening change anything?

Expert opinions deeply appreciated.

Jay

ICBM

Acoustic resonance - no.

Electric tone - it can do. Paint is fine, and foil lining the control cavities also doesn't seem to change anything, but overdoing foil around the pickups does seem to make a difference, and the closer the shielding is to the pickups the worse it is. If it's conductive metal foil the effect could either be due to capacitance or the generation of 'eddy currents' in the foil, just as with metal pickup covers - only not as much, because those are thicker and much closer to the coils normally.

I've come across a few examples of over-shielding dulling the tone on Strat-type guitars - including my one many years ago when I was just starting to mod guitars - because I'd read that you could cure the typical Strat noise by foil lining the pickup covers and replacing the wiring with shielded cable. Firstly it didn't cure the noise (as I only realised later, that's mostly magnetic, not electrical interference) and secondly it very noticeably muddied the tone. I removed it all - very annoying given how much of a faff it was to do in the first place! - and shielded the cavity with paint instead and it was fine.

jaymenon

Thanks John - the only problem with graphite paint is that removing it is difficult...!

ICBM

jaymenon said:

Thanks John - the only problem with graphite paint is that removing it is difficult...!

You don't need to bother. Even if you don't want it, just leave it not connected to ground and then it will neither act as a shield or produce any capacitance.

To be honest, I don't find it quite as effective as a shield as foil anyway - although it's certainly less hassle to do than a really complete foil job. But it's a good halfway house.

Danielsguitars

Would shielding just the pickguard be enough with strat type guitars, I'm no expert on these type of builds so hopefully I'll learn something

sixstringsupplies

customkits said:

Would shielding just the pickguard be enough with strat type guitars, I'm no expert on these type of builds so hopefully I'll learn something

Yes it would. It would provide sufficient shielding. 

ideally though, to *truly* shield a guitar properly you need to make a faraday cage. If you’re just going to use copper foil or paint in the cavities and not convert it into a faraday cage (ie. shielding the cavity covers or pickguard so that when screwed back down in place it comes into contact with the shielding inside the guitar, it’s not as effective. 

Gagaryn

I think the aluminium pickguard I had on my JM for a while affected it's tone, was subtle but it seemed to sound thinner, less full and a bit honky. Basically just a bit more shit.

thermionic

The effect of a complete aluminium pickguard shield on a Strat’s tone has been described many times. Personally I didn’t notice much of a change. I’ve done a full copper foil/aluminium foil on the pickguard shielding job on a couple of guitars but I don’t think it’s worth the effort. Standing in a slightly different position reduces noise more than the shielding did.

Danielsguitars

what about vintage tele and strat's

I'm more into gibbo stuff and no one really complains about them, maybe a bit of p90 noise but nothing worth bothering with imo so I don't 

I'm of the opinion if it ain't broke don't fix it

ICBM

It's also worth paying attention to doing the wiring properly.

I just worked on this - which is a Custom Shop Fender, no less - and the wiring is an utter disgrace. Unsurprisingly it was very noisy - there's no shielding at all, and there's miles (well, at least a foot in total ) of loose single-core wire which all picks up buzz and hum.



Simply taking it all apart and re-doing it like this at least *halved* the noise level, without adding any shielding - and without altering the tone in any way. Twisting the wires together both partially shields the 'hot' wire against buzz and gives pseudo-balanced hum rejection.

Danielsguitars

twisting together wire makes sense, just like heater wiring in amps

Looks much better too and more professional, 

Gagaryn

ICBM said:

It's also worth paying attention to doing the wiring properly.

I just worked on this - which is a Custom Shop Fender, no less - and the wiring is an utter disgrace. Unsurprisingly it was very noisy - there's no shielding at all, and there's miles (well, at least a foot in total ) of loose single-core wire which all picks up buzz and hum.

Simply taking it all apart and re-doing it like this at least *halved* the noise level, without adding any shielding - and without altering the tone in any way. Twisting the wires together both partially shields the 'hot' wire against buzz and gives pseudo-balanced hum rejection.

Yes, I always twist the wires like that, thought it must help.

I need to tidy up the wiring in my JM, you know how you see those photos with amazingly neat wiring like this - 



Well mine is nothing like that, must be about a mile of extra cable in it. It's silent though.

jaymenon

Does using a shielded cable from the volume pot to the output jack make a difference?

Lebarque

I twisted my strat pickup wires once, but I was sure it dulled the tone, so undid it.

ICBM

jaymenon said:

Does using a shielded cable from the volume pot to the output jack make a difference?

To the noise, yes - often the most of any cabling in the guitar, it’s the most prone to picking up noise, especially when the volume control isn’t up full. It also doesn’t affect the tone, because it’s actually just an extension of the guitar lead, which is shielded anyway.

Lebarque said:

I twisted my strat pickup wires once, but I was sure it dulled the tone, so undid it.

I think that’s highly unlikely. There’s no significant change in capacitance, unlike with using extra shielding.

aord43

Premier Guitar has some articles regarding shielding pickups - basically don't let the ends meet, if you want to avoid eddy currents.  If you fail to do it properly you lose high-end, apparently.  I shielded my strat cavity and pickguard, and replaced the wiring with all shielded cable.  I didn't do the pickup covers.  I also changed pickups at the same time so I am not able to see if there was an effect on tone, but it sounds great to me.
Twisting makes sense, computer network cable (cat5 etc) doesn't have a shield but uses what's called "twisted pair", ie. each pair of conductors (there are 8 in total) are twisted together to avoid noise being induced from outside.

jaymenon

Took the plunge and graphite shielded my WudTone strat - noise is much much better, and there was no discernible negative effect on tone.

Very very pleased...!

Rabs

A lot of the stuff I have read and seen on youtube about shielding recently seems to point to its better (read easier) to use shielded wire for your circuits than using paint or copper tape to create a Faraday cage...

ICBM

Rabs said:

A lot of the stuff I have read and seen on youtube about shielding seems to point to its better to use shielded wire for your circuits than using paint or copper tape to create a Faraday cage...

If the Faraday cage is good, it isn't - the shielding effect is the same, but a large Faraday cage adds less capacitance than individually shielded cables since the separation of the conductors is much greater.

To be honest I have found conductive paint to be a less effective shield than thoroughly-done foil though, so it's likely that shielded cable may be more effective than paint.

What I mean by 'throughly-done' foil is a complete cavity lining of copper tape with all joints soldered across in at least one spot to ensure complete conductivity, and a wire linking it to a ground for the same reason - not just relying on contact between the pieces to make the connection. I've done a few of these in instruments which were still noisy even with a painted cavity, and cured it.

Rabs

ICBM said:

Rabs said:

A lot of the stuff I have read and seen on youtube about shielding seems to point to its better to use shielded wire for your circuits than using paint or copper tape to create a Faraday cage...

If the Faraday cage is good, it isn't - the shielding effect is the same, but a large Faraday cage adds less capacitance than individually shielded cables since the separation of the conductors is much greater.

To be honest I have found conductive paint to be a less effective shield than thoroughly-done foil though, so it's likely that shielded cable may be more effective than paint.

What I mean by 'throughly-done' foil is a complete cavity lining of copper tape with all joints soldered across in at least one spot to ensure complete conductivity, and a wire linking it to a ground for the same reason - not just relying on contact between the pieces to make the connection. I've done a few of these in instruments which were still noisy even with a painted cavity, and cured it.

Yes...  I do shield my guitars now with copper tape and I also have read the same thing about joining the pieces with wire and grounding that wire... I do it by running a piece of wire from one corner so it goes over each leaf and then stick some copper tape on top of it rather than soldering and run that back to the control cavity where it get twisted with the bridge and other grounds. Seems to work ok for me. Had no complaints so far

In saying that ive sold a guitar which had no shielding at all and has been used in studios and on stage and he says hes never had an issue.. Go figure But I just think now, better to do it than not cos I do know that electrical interference can be a big issue for some.

When I was in a band years ago, the other guitarists had something about his rig where he would occasionally pick up some local radio frequencies ... (it was a Strat)...

normula1

You should solder the copper tape as over time the joints oxidise and become less conductive.