Cavity/pickgard shielding

[moobox]

Well, I have my body all painted. I ordered some copper tape from Stewmac (all 3 widths). Now how the heck do I shield the body? Do I just cut up little strips until that whole cavity is shielded? And should I shield every cavity ie. jack cavity, spring cavity, the whole swimming pool thing?

As for the pickgard I got from Warmoth, it has a bit of silver stuff just where the controls will go. Do I need to shield the rest of the gard?

Sorry hey, I'm not sure of this at all. Just know that it must be done.

Cheers - Ed

 

[bagman67]

Hi, Ed -


There are two things in play here: electronics and aesthetics.


As an aesthetic consideration, shielding can be gratifying because it gives you that lovely copper-lined cavity, etc., etc.  How much you choose to shield is really a matter of how you want it to look in there.  Because:


As a matter of ELECTRONICS, the shielded chamber you create is likely to make only as much difference as you convince yourself it will make.  The great big holes the pickups poke out of, and so on, make the attempt at a fully shielded cage (called a Faraday cage) ineffective. 


Now, some folks report an improvement in hum management as a consequence of shielding, and I can't tell you they're wrong, but I can tell you this:  Even a lot of premium builders cranking out very sophisticated axes don't bother to shield. 


But what I would do is go searching for pictures and try to replicate the best of what you see.  If you come close to that, you'll probably be as close to perfect as a shielded cavity can get.


In particular, I recommend you seek out builds by a guy named Ron Kirn over on the tdpri.com board.  He does some very well documented builds with lots of photos, so go search him out on their Tele Home Depot sub-forum.

 

[Jusatele]

ever studied faraday cages
the first thing you learn is you have to enclose a item fully, such as on all6 sides not just 5.
Go ahead and shield that puppy on 5 sides.

 

[moobox]

So, what I'm getting from this is that it's a waste of time. Makes it easier for me I guess. Just wondering why there is so much talk for it.

 

[AutoBat]

^Pretty much. Didn't stop me from doing it to my strat though. I was young and foolish back then.

 

[Picklemitts]

I just shielded my strat the other day.  It made no difference that I can tell.  Using position 2 or 4 seems to be the only thing that works on hum.

 

[fdesalvo]

You won’t notice any difference in noise level that is attributed to 60-cycle hum or poorly regulated/filtered AC.  When you find yourself around fluorescent lighting or other sources of interference, a properly shielded cavity will absolutely make a difference.

 

[Cagey]

You have different laws of physics in your neighborhood?

 

[fdesalvo]

Jigga please.  Newtonian physics flows from all the faucets in OC, and string theory from every electrical outlet.  Whatchootalkinbout?

 

[Jusatele]

As stated, shield is a farst. half that pickup is above the pickguard. If you cannot del with that then how is shielding going to work?

 

[fdesalvo]

Call me crazy, but I had a SG (with covered hums) that benefitted from cavity shielding.  Yeah, open coils - I can see that being pointless.

Directional sources of emi can be intercepted or rejected by use of shielding - a fully enclosed cavity isn't entirely necessary against certain kinds of interferance.  You can get the gist of the effect by placing your guitar in front of a CRT monitor and angling it away while observing the varying levels of noise.  There are several products on the market for mobile phones, for example, that provide ample shielding by only adding a film on one side of the device. 

 

[MSP]

I'm certainly no expert on the technical aspects of shielding, but wouldn't partial shielding still act like an, umm, shield?  Even if everything's not fully enclosed, wouldn't it still inhibit eternal electrical interference?

 

[Cagey]

Think of it like being under water. How watertight does your environment need to be before it's acceptable? If it's not totally enclosed, Is there a point where you only sorta die, or do you die no matter what?

It's not a perfect analogy, but it's close enough for ork 'n' orr.

 

[MSP]

Ah, okay.  Thanks for the illustration.  In my mind it was more like sealing a room from light: you might not get perfect darkness, but you can drawn the blinds and make it darker.

 

[fdesalvo]

The trouble is there is more than one kind of interference and it's all but impossible to protect yourself against them all. 

 

[rkoeper]

Hey guys,

I'm confused about the faraday cage. IIRC a faraday cage is able to shield every wavelength that is longer than the magnitude of its openings. Wavelength of power outlets is thousands of kilometers, wavelength of fluorescent lights (frequency about 30 kHz) is about 10 km.

So any opening of the magnitude of centimeters shouldn't matter at all. But seemingly they do. How so?

 

[Cagey]

The pickup itself is an antenna that's probably a kilometer long. Also, harmonics.

 

[Super Turbo Deluxe Custom]

There is something to be said for using shielding tape on the backs of pickguards and control cavities.  Not because they shield, per se, but allow static to "drain".  Many may never experience this, but I have, and it is noticeable before and after.

 

[rkoeper]

Hey Cagey,

pickup as an antenna - sure. That's the problem with single coils and no shielding will get rid of this. But shielding the cavities should get rid of any extra noise that would come in through unshielded wires, right? And at least for hum buckers that should be the major source of noise.

rk

 

[bagman67]

Hey Cagey,

pickup as an antenna - sure. That's the problem with single coils and no shielding will get rid of this. But shielding the cavities should get rid of any extra noise that would come in through unshielded wires, right? And at least for hum buckers that should be the major source of noise.

rk

In other posts, I believe Mr. Cagey has advocated the use of shielded wires in wiring up a guitar with humbuckers.  Forgive me if my memory is at odds with reality on this point.