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Shielding components from EMI/RFI... Help please

A recent experiment with a product designed to reduce EMI/RFI left me curious about other ways to reduce EMI/RFI in my system. In the past ten days, I've stepped onto a slippery slope, at the bottom of which is surely some kind of insanity...

I've been experimenting with copper plates in an effort to absorb, deflect, diffract, and block EMI/RFI. I've tried copper plates under components, on top of components, and inside components.

This is the point where you tell me I don't know what I'm doing and I'm likely to short circuit something and/or electrocute myself. Consider me duly warned. This is also the point where you tell me to get some balanced interconnects, or at least to get some shielded interconnects for Chrissake. Consider me duly informed. Moving on...

I'm hoping you can help me make the most of this experiment, and help me avoid killing a component or myself. My strategy so far has been to:

1. Place copper plates at locations that generate a lot of EMI/RFI, e.g., components with switching mode power supplies or high frequency clocks. The system has a total of 3 SMPS and 3 clocks.

2. Place copper plates at locations that are vulnerable to EMI/RFI, e.g., under the amp, near the transformer.

3. Place copper plates inside noisy components -- in particular, my Meridian G68 preamp/processor. I've begun to build 2 partial Faraday cages, one for the SMPS, and one for the analog output stage.

4. Ground the copper plates either to the component chassis (when plates are used inside a component) or to an independent ground point (when plates are used above/below a component).

Has anyone tried this sort of thing?

Bryon
bryoncunningham
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almarg
9,670 posts
 
Also, in many cases either the letters UTP (unshielded twisted pair) or STP (shielded twisted pair) will appear on the cable.

Or if a manufacturer's part number appears on the cable, Googling that number will presumably lead you to a description of the particular cable, and whether or not it is shielded.

I believe that it is considerably more common for CAT 5e cable to be unshielded than shielded. Not sure about CAT 6.

Another point to keep in mind, I believe, is that the shield in most or all shielded ethernet cables will only be grounded if the jack it is plugged into makes that provision, and I believe that only shielded jacks will do so.

Best regards,
-- Al
sarcher30
596 posts
 
I am guessing that consumer equipment is unlikely to have sheilded jacks if most ethernet cables are unsheilded? Oh well. They only set me back $25 with shipping.
bryoncunningham OP
890 posts
 
Thanks, Al. My Cat 5 cables are unshielded. I just ordered some shielded Cat 6.

Yesterday I received the materials to complete the DIY projects described in the OP. Hopefully there will be some results. I will report back.

bc
sarcher30
596 posts
 
Bc, I should get my cat6 tomorrow. I will report back if I hear any change. I have my doubts though. Please let us know how your projects work out.

P.S. I like your real room. Nice and tidy. If not for the speakers you would not know an audiophile lived there.

Sean
bryoncunningham OP
890 posts
 
Thanks, Sarcher. Interested to hear if the Cat6 makes any difference.

I have an update...

I have installed 7 copper plates inside my preamp/dac. They are each 16 gauge, or .06", which is fairly thick. I grounded each plate to the chassis. I bolted 3 plates around the analog output stage, 3 plates around the power supply, and 1 large plate to the underside of the lid.

The results are surprisingly good. The noise floor dropped noticeably. The resolution increased slightly. The high frequencies got smoother. I can turn the volume up about 3dB with the same comfort level.

I've tried quite a few tweaks and mods, and this is one of the most audible. The results are much more obvious than when I recently added ERS cloth to the preamp/dac. Total cost for this mod: about $100 in copper from an online retailer, who also cut the plates to exact sizes.

Next up: I'm building a copper/aluminum enclosure for my reclocker. The enclosure will be grounded to a dedicated ground rod I just buried under the house...

...to be continued.

Bryon
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