EMG cavity shielding

[SpiderVenom]

This is one of those questions I'm asking merely because I want to know the answer, but here goes... is it worth copper shielding the control cavity of an EMG loaded guitar? Although EMGs themselves are fairly immune to interference, wouldn't the controls themselves still be subject to it? My second thought was that if you did do this, would it cause a mess of ground loops through contact with the pots (based on EMG's diagrams)?

 

[dani]

Re: EMG cavity shielding

emgs need no cavity shielding. they are internally shielded.

 

[SpiderVenom]

Re: EMG cavity shielding

emgs need no cavity shielding. they are internally shielded.

But their pots aren't shielded...? After all, lots of people leave their passive 'buckers in factory condition but shield the control cavity, so what would the point of that be if only the pickups were the problem?

 

[octavedoctor]

Re: EMG cavity shielding

emgs need no cavity shielding. they are internally shielded.

That's quite correct, but the wiring is still potentially vulnerable to inductive noise. What keeps this minimised is the low impedance of the pickups output which helps to damp oscillation in the input stage of the amp. This means that the induced noise is kept to a low level relative to the signal (high s/n ratio).

This doesn't mean that the guitar won't benefit from cavity screening, just that guitars with EMGs are less vulnerable.

Basically, you can't have too much screening.

I was support tech for an EMG distributor for 6 years...

 

[SpiderVenom]

Re: EMG cavity shielding

So would covering the cavity with copper shielding cause any grounding problems due to contact with the pots?

And I assume the idea would be to make sure the copper shield is continuous and grounds to a pot?

 

[octavedoctor]

Re: EMG cavity shielding

Absolutely. That's the case with all sscreening.

Some people on here have reported an increase in noise after screening; this happens when you don't do it properly. It has to be contiguous (no gaps) and connected to the guitar's earth circuit.

 

[bryvincent]

Re: EMG cavity shielding

i shielded my EMG-loaded SG Speacial Faded and has no problem with grounding whatsoever. in electrically noisy places like my house, EMGs can still pickup EMI and shielding the cavity will minimize that quite significantly.

 

[SpiderVenom]

Re: EMG cavity shielding

Ah, nice pic, explains a lot. Just one question... how did you deal with grounding the foil. Did you solder a wire from it to a pot?

 

[bryvincent]

Re: EMG cavity shielding

no, i didn't solder any thing to the foil, it is on contact with the input jack ground

 

[octavedoctor]

Re: EMG cavity shielding

You wouldn't be able to solder to aluminium anyway, but the screen is in contact with all the pots and the jack anyway. You only need to hardwire a link in if you've got a guitar with all the pots moutned on a scratchplate.

 

[SpiderVenom]

Re: EMG cavity shielding

You wouldn't be able to solder to aluminium anyway, but the screen is in contact with all the pots and the jack anyway. You only need to hardwire a link in if you've got a guitar with all the pots moutned on a scratchplate.

*slaps forehead* Yes, it would be just like me to go and thoughtlessly solder to aluminium. "Hmmm, what's that burning wood smell?"

Didn't think about the pot contact thing either. Even if it wasn't touching the jack, it'd still have a path to ground through the pots. Well, when I assemble my next guitar (beginning of next year ), I'll know what to do with shielding now. Thanks.

Edit: Just one question. I assume the standard EMG diagrams from the website will work fine with a shielded cavity?

 

[octavedoctor]

Re: EMG cavity shielding

Edit: Just one question. I assume the standard EMG diagrams from the website will work fine with a shielded cavity?

Certainly will!

One thing to watch though, particularly with foil screening, is inadvertant shorts to earth caused by signal points making contact with the foil. Occasionally you can get bits of foil coming loose an causing this. The rivets holding the solder tags to the pot tracks are favourite sources of this particular irritation. You only need a bit of wrinkly foil under one pot and suddenly it's gone all quiet...

 

[SpiderVenom]

Re: EMG cavity shielding

I'm planning on using adhesive copper tape, so that shouldn't be a worry, with any luck (but thanks - at least I'll know something to check if it does happen).