Use of Copper Foil for RFI / EMI

In another active thread a forum member stated how he uses copper foil for EMI / RFI reduction. It's not clear to me how to best use this. Not so much interested in the theory but the mechanics of how and where to actually apply it. Info on the best materials and their sources also appreciated. And if anyone can show or point to photos of the foil applied.

Thanks.

ps sandyk is not welcomed to this thread

Why so ?

sandyk is not welcomed to this thread

In another active thread a forum member stated how he uses copper foil for EMI / RFI reduction. It's not clear to me how to best use this. Not so much interested in the theory but the mechanics of how and where to actually apply it. Info on the best materials and their sources also appreciated. And if anyone can show or point to photos of the foil applied.

 

Thanks.

 

ps sandyk is not welcomed to this thread

As applied to what?

If you want an instant 20dB reduction of EMI/RFI use the metal conduit that romex is pulled through for commercial building installs and ground it.

That's taking a very long shot that you actually have external EMI/RFI in a typical home environment to worry about. Most likely you don't.

There is also faraday cage spray paint.

Shielding supplies

http://www.mouser.com/Tools-Supplies/Adhesive-Tapes/_/N-wp6v?P=1yzv2xq&pop=76wx

Mesh Foil to make transparent EMI / RFI shielded windows and displays

A little explanation:

Hum Rejection in Unbalanced Audio Cables -- Blue Jeans Cable

Nice 7 second video on how much it can help.

For the truly paranoid:

Frequently Asked Questions: EMF Shielding

Don't see why you single out sandyk in your thread. He might be rather helpful in matters of this topic.

You can figure the rest of it out on your own since you want to be picky about where your advice comes from.

And if anyone can show or point to photos of the foil applied.

Well, recalling example where Marantz engineers used copper foil to shield underneath of DAC board (and connection cable) from below's Analogue...

HD-DAC1 uses a Cirrus Logic CS4398...

 

ps sandyk is not welcomed to this thread

That's uncalled for.

There is also faraday cage spray paint.

Seriously? I want to get some, even if I have no idea of how I might use it.

Seriously? I want to get some, even if I have no idea of how I might use it.

Electromagnetic Field Shielding Paints

You just roll it on, and ground it somewhere. Blocks wifi and other stuff. Otherwise, You better Call Saul. Well actually his brother.

A cheaper solution is a galvanized metal trash can. Seems with all the hysteria regarding EMI around computer audio every PC should be in such a can and every DAC should too. Not a high WAF factor though.

It's a really complex subject, the more you read about it, the more you see how specialist it is. I started it as a cheap easy experiment on the plastic covered Intona. Equipment is regulated on FCC emissions testing, not how well it's covers reducing noise going to the DAC.

But I am not comfortable in shielding from members......No matter how noisy the interference.....

That's CA admins job.... Sorry... I'd love to join in. and help if I can..but...?

Ask away on the other thread by all means....

Sent from my SM-G900F using Computer Audiophile mobile app

That's uncalled for.

Thanks for your opinion. If you saw what he did to my other thread you'd know why.

Anything to contribute on this topic?

Shielding supplies

 

http://www.mouser.com/Tools-Supplies/Adhesive-Tapes/_/N-wp6v?P=1yzv2xq&pop=76wx

 

Mesh Foil to make transparent EMI / RFI shielded windows and displays

 

A little explanation:

 

Hum Rejection in Unbalanced Audio Cables -- Blue Jeans Cable

 

Nice 7 second video on how much it can help.

 

 

For the truly paranoid:

 

Frequently Asked Questions: EMF Shielding

 

Don't see why you single out sandyk in your thread. He might be rather helpful in matters of this topic.

 

You can figure the rest of it out on your own since you want to be picky about where your advice comes from.

Thanks for the useful links.

It's because of the mess he made here: http://www.computeraudiophile.com/f10-music-servers/best-reasonable-cd-ripping-practice-29863/

Thanks for your opinion. If you saw what he did to my other thread you'd know why.

 

Anything to contribute on this topic?

You can ask Admin for off topic, or types of replies you don't wish to see, removed , and the poster concerned to stop posting them, but you can't dictate who is, or isn't , permitted to reply in the threads you start !

You can ask Admin for off topic, or types of replies you don't wish to see, removed , and the poster concerned to stop posting them, but you can't dictate who is, or isn't , permitted to reply in the threads you start !

Regardless, I'm not interested in your input.

No, wait, I'll change that. If you can manage to behave and make meaningful contributions then please do so. Just don't do what you did to my last thread. Despite your penchant for hysteria I do admit you seem to be a pretty smart guy.

There is some Black Magic involved in EMI/RFI and the higher the frequency the less predictable it gets. But first there needs to be a source of the interference and there needs to be a hi-fi component susceptible to that type of interference.

Henry Ott wrote an 850 page book on the subject:

EMC Books

Jim Brown, past AES committee co-chair on EMI/RFI wrote about 1000 pages on the subject.

Audio Systems Group, Inc. Publications

*******************************

Now getting back to copper foil. Yes correctly applied foil can act as shielding and shielding is always a good plan.

But it's a problem solver not a magic bullet.

A silver bullet would be nice.... Just too shoot me for looking into this....

There are so many variables to be specific. Only a completely closed box works but those pesky cables.... I so far kept it simple... Aluminum tape and copper tape these block external RFI. It can also reflect from the internal emissions.. Metal like MU metal can absorb EMI like sponge depending how thick the metal and strong the field. Shaping the field line's.... but a small amount is as expensive as a cast Aluminium project box.

A mix of cheap metals seem the better course....Making sure the smallest gaps are covered mean higher frequencies can't get in. You can't stop transmission of everything so a mix of copper aluminum as I see it act as a broader spectrum shielding.... Wires with good copper braid and silver foil... terminations attached to the shield.

You can see the obsession with clean power and signals so I am suprised there hasn't been more discussed especially by some of the industrial experts lurking....

Overlapping tapes at joints, a drain wire were possible. I am having a blast at shielding a toroidal transformer in my LPS with the mu metal and copper.

I just soldered a wire to the MU metal and tacked it onto the earth on the IEC connector. Blocking the AC side from the DC to see if it helps....

The main thing is as I am no expert to say the least...Cheap experiments safely done... Have a listen.. Unless I get some serious electronic qualifications and access to a high grade spectrum analyser. .. A few engineers at work said they see if it works.....

My transport is floating (battery) But the Intona shielding did sound better.

Suck it and see... Then try again...

Ultimately design mitigation is the key....What can be done for extra cost in amps dacs I am not sure. Cost V gains....

Sent from my SM-G900F using Computer Audiophile mobile app

Thanks for the useful links.

 

It's because of the mess he made here: http://www.computeraudiophile.com/f10-music-servers/best-reasonable-cd-ripping-practice-29863/

I had not read that other thread, so I understand where you are coming from now.

Still I think Alex (sandyk) is a good guy. Don't throw the baby out with the bathwater.

Thanks for your opinion. If you saw what he did to my other thread you'd know why.

 

Anything to contribute on this topic?

I assure you he has treated me much worse than he has treated you.

The worst thing you can do with that kind of irrational religious zealotry is feed into the persecution complex.

Copper foil is good for RFI kind of things, but not so good for EMI in case there is magnetic conduction. Tin-plated magnetically responsive steel (*) is good because it works on wide variety of interference types. "The good ol' tin can" material.

*) My vocabulary for steel chemistry is failing right now and I don't remember what was the correct name. Anyway, there are different types of steels, some types respond to magnets while other types don't. Depends on the internal structure as result of manufacturing process.

Copper foil is good for RFI kind of things, but not so good for EMI in case there is magnetic conduction. Tin-plated magnetically responsive steel (*) is good because it works on wide variety of interference types. "The good ol' tin can" material.

 

 

*) My vocabulary for steel chemistry is failing right now and I don't remember what was the correct name. Anyway, there are different types of steels, some types respond to magnets while other types don't. Depends on the internal structure as result of manufacturing process.

Is "ferromagnetic" the word you're looking for?

Copper foil is good for RFI kind of things, but not so good for EMI in case there is magnetic conduction. Tin-plated magnetically responsive steel (*) is good because it works on wide variety of interference types. "The good ol' tin can" material.

 

 

*) My vocabulary for steel chemistry is failing right now and I don't remember what was the correct name. Anyway, there are different types of steels, some types respond to magnets while other types don't. Depends on the internal structure as result of manufacturing process.

Are you thinking of mu-metal?

https://en.wikipedia.org/wiki/Mu-metal

Or just galvanized steel.

Is "ferromagnetic" the word you're looking for?

Yeah, I think so, ferritic as opposed to austenitic steel.

Man, this is great stuff. I am convinced we are not prepared for the mother of all solar flares. Now I can paint my house with Pliskins' "faraday cage spray paint."

No more worries about those pesky North Koreans, ISIS, or ole' Mr. Sun.

I am sure the power grid is fully prepared for disaster, natural or otherwise.

I guess my thoughts are on local sources and protection, i.e. coming from the components themselves and protecting circuitry, chips etc within their local fields.

Should I assume generally speaking there are harmful fields coming from transformers and maybe certain other items? And that generally speaking there are certain items (DAC chips and ?) that are sensitive to these fields? Therefore these items could be either treated to prevent radiation leakage, or treated to prevent being hit by radiation?

I guess my thoughts are on local sources and protection, i.e. coming from the components themselves and protecting circuitry, chips etc within their local fields.

 

Should I assume generally speaking there are harmful fields coming from transformers and maybe certain other items? And that generally speaking there are certain items (DAC chips and ?) that are sensitive to these fields? Therefore these items could be either treated to prevent radiation leakage, or treated to prevent being hit by radiation?

See you can worry about it all, and imagine it happening, and it is at some very low level. But how low and does it matter. You sometimes run into issues. I have used foil or metal to fix such things before, but this idea your gear is pervasively having trouble is one I rather doubt. I also don't think change stuff and listen is an efficient method to go about this. Measuring it is.

I once did an experiment where I wrapped some RCA interconnects three times around a high powered gaming PS outside the case of the PC and with the PC under heavy load. Recorded the result and yes there was low level hash and it was barely audible. Unwrap and move those a foot away (30 cm) and all the garbage was not there. It was well below the noise floor. I also wrapped some XLR interconnect 5 times around the same PS, and there was nothing picked up. That is another thing I see lots of here on CA. People worried about picking up stray signals and going to expensive inconvenient add on solutions to the problem yet not using gear with balanced connections. Heck using balanced gear helps bunches if you fear radiated noise problems.

Are you thinking of mu-metal?

 

https://en.wikipedia.org/wiki/Mu-metal

 

Or just galvanized steel.

Mu-metal would be fancy and good, but also plain tinned (not zinc!) steel works fine. Most of the shield cages attached directly to PCBs are just tinned steel, and many board houses are able to manufacture such also.

There are of course bunch of companies specializing on these things, like:

1500 - 1800 series PCB shielding cans & compartment shields

they have primarily two materials "mu-copper" and "tinned steel". For example pretty much every TV and VCR (old days) have the primary antenna RF parts housed in such internal tinned steel case. Many people have probably seen those.

I've just purchased plain bulk tinned steel sheets in the past, cheap and works well and easy to deal with. Ground wire can be soldered directly to the sheet.