Use of Copper Foil for RFI / EMI

[Cornan]

Nothing has lower impedance than a straight wire.

Yes, but braided wires have lower rf restistace which makes it a good conductor.

 

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[Speedskater]

Ah dam.... I asked the engineers what a low impedance wire was.. they picked solid wire.... Not as thick as that....

Kind regards

Dave[emoji2]

At low frequencies the greater the cross-section area, the lower the impedance.

But at high frequencies, flat braided wire, flat straps and Litz wire will have lower impedance than a solid or stranded wire of the same cross-section area.

Of course, length is the biggest factor.

[mansr]

Yes, but braided wires have lower rf restistace which makes it a good conductor.

 

Can you hear radio frequencies?

[Cornan]

Can you hear radio frequencies?

 

My bad. It should be low resistance not low rf resistance.

 

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[sandyk]

I found these articles and made me think about the Caps in audio pcbs.....Vibration is part of our environmental testing in work.. We shake 4 big surface mount PCBS in the a Y axis to give greater abuse a plane engine can give. We strap and bond our caps down but they work fine.... Audio ...So would 3 dots of silicone work...? on loose free standing electrolytes Rather than float on 2 wires....

You will find that many commercial; products have a cement like substance around the base of larger capacitors to firmly anchor them.

[mansr]

My bad. It should be low resistance not low rf resistance.

 

A straight wire has the lowest resistance. As frequency increases, capacitance and inductance become more important, and thus depending on the application, other topologies may give better results. Now below 1 MHz or so, none of this matters. Depending on the signal level, shielding may be an issue, but that's a separate concern.

[Middy]

Right then my late night MOD rough but done.

 

I curled under the the metal back on its self at the bottom..... The MU Metal wasn't wide enough to wrap in one large piece so I have stripped back the insulation in 4 places and bonded one wire around the mu metal. Can't hurt....?

3 Kapton solid wires soldered 1/3 spaced around the shield..... wrapped around then twisted and soldered to the earth..

No real heat off this BTW I checked yesterday..... I light twisted (pig tail) to reduce length as suggested in the tech paper.....

 

A very Frankenstein rough job taking pieces of different techniques as I am just guessing....

 

If there is no objections i will wrap the Caps in copper and place a little silicone sealer in three places for vibration dampening tommorow ..is that safe ...heat? with no shorting of course........... If it matters.... but in for a penny in for a pound.....

Something is different... I think better....

 

Pics for a laugh how bad it looks but safe... I think....

 

I hope I am not embarrassing myself too much..

 

Have fun all and nn

Dave[emoji2]

 

 

 

 

 

 

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[Middy]

I do running tests as a late night listen when the house is all switched off and quiet and first thing when I wake up as my ears have rested.. My theory anyway.....

But I think with my version of Doc Brown's flux capacitor I have a winner....

 

Trying to split up the 3 sections.. AC side.... The Transformer and DC out......

 

I think it sounds better.. much better..... on my LPS anyway....

 

So Alex doesn't tell me off... Make sure an electrician or qualified person verifies basic safety. . ( I do not want anyone hurt) This is my MOD.... any risk is mine...

 

Blind luck and stealing ideas 1 ....

Electronics Degree 0......

 

This ties in with the Power side of shielding...

 

Bonding helps ???

extra metal on top of the Mu metal? ??

Curl up the plate on its self to help with sharp edges and magnetic fields ...???

3 solid core wires soldered spaced even and twisted and soldered to Earth???

 

Further tweaks ??

May be curl over the top ? In cross section make a tall C shape to help with field line management and match Toroidal shape???

Add steel foil ?

 

Just guessing on why it works and the little extras on top of just one wrap of MU metal....

 

Cheers

1 suprised

 

Dave

 

Material cost $30 + bits I have lying around....

 

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[Cornan]

Looking for DC magnetic shielding I found this little interesting youtube video:

 

 

It seems that GIRON material have a lot better magnetic shielding properties (for stronger magnetic fields) than MU metal. Could be an interesting material to use. Thinking that this material could be useful in shielding my battery packs since they are pretty close to my audio gears at the moment.....hmmm?

[Cornan]

Further tweaks ??

Well you can for example change that mains fuse to a hifi tuning fuse (valuable AHP fuses for example) and change the IEC socket to a Furutech AC-1001 with mains filter or similar (just make sure it fits).

If your DC output cable do not have a ferrite clip on the cable you could add one as well. YMMV applies!

[Middy]

The Sbooster designer said they tried 50 different fuses and picked that one shown..... I fitted a Synergistic research black UK 3 PIN on the power cable..... It changed the sound and being a 'snake oil' product to some..... did suprise me it worked, a speaker guy in work badgered me to try one. Not sure if I want to spend that much again...But it does work ( changes sound) and I hate to say so ?... It is deoxited clean and Cilclear....

 

The space I have in there the Giron would be too thick... It's waffle shape and as the video shows you need layers for better effect... I had the MU before I saw that video.... Not sure of the cost.... All EMI shielding is still in the expensive specialist domain....

 

The guys in work mentioned just use a big ferrite but wasn't sure if it doesn't add issues on a DC line?

 

I will try some copper tape on the caps for fun.... And try and get the filters on my Tacima power strip with MU.

Thank you as always, for the tips and encouragement...

I just hope it helps others for minimum cost..

Cheers

Dave

 

 

 

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[Cornan]

Unfortunately not all tweaks are cheap! However, a "tweak" that could be fairly cheap is to dampen and isolate LPS from vibrations with things like for example Antiphon inside the case (where possible) and Novibra used as damping feets.

Copper taped caps might be good but I cannot tell if it is a good tweak or not. Just go ahead and try it...for the fun of it!

[Cornan]

I think I came across whole threads on doing extensive shielding work in the computer on a JPlay forum, it was a couple of years ago, but you should be able to find it again, with lots of pictures in it.

Hi YashN! Might this be the thread you was refering to? Can the guys who've used EMI/RFI paper (SOtM, 3M, etc.) post photos here of how you did it? - Computer Audio - JPLAY - hi-end audio player for Windows Looks like interesting information for this thread indeed!

[sandyk]

Unfortunately not all tweaks are cheap! However, a "tweak" that could be fairly cheap is to dampen and isolate LPS from vibrations with things like for example Antiphon inside the case (where possible) and Novibra used as damping feets.

 

Some people mount PCBs using small rubber grommets to reduce the effects of external vibration.

This is also done when fitting SSDs to aluminium mounting adaptors in PCs.

The old Musical Fidelity X-DAC V3 is mounted on slide in rubber lengths to reduce vibration which could affect it's Xtal Oscillator.

Some even fit large self adhesive domed rubber feet to the top of their large electrolytic capacitors.

 

Alex

[Cornan]

Interesting Alex!

Some even fit large self adhesive domed rubber feet to the top of their large electrolytic capacitors.

It reminds me about my tube tweaking days. I wonder if Duende Criatura tube rings (or the general idea) would work for those capacitors as well?

[YashN]

Hi YashN! Might this be the thread you was refering to? Can the guys who've used EMI/RFI paper (SOtM, 3M, etc.) post photos here of how you did it? - Computer Audio - JPLAY - hi-end audio player for Windows Looks like interesting information for this thread indeed!

 

Yes, that could be it, there are other threads too.

[Middy]

Heat was my only concern with foiling the Caps and using silicone at the base . That's why I thought a tripod .. 3 dots just to support them and allow some air flow A total bead would be better as it has more mass to absorb...

Well in my thinking it would . .

Might not do much on an LPS but I don't want to play on my Brooklyn. ...but if it does benefit...shielding and vibration management on Caps I may try it. LPS £200 ....Mytek £1700....

 

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[Middy]

http://learn.interferencetechnology.com/2016-emc-filters-guide/

 

A free guide from a company... I don't know what people think of the Filtered IEC sockets....

 

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[semente]

Yes, but braided wires have lower rf restistace which makes it a good conductor.

 

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Could RF resistance be an asset in certain uses such as analogue interconnects?

 

R

[Middy]

Another late night MOD job with the last of my copper tape....

 

Like I said ...I don't know how much RF OR EMI if any comes off Capacitors ..in general... power and rating of the caps.... Dependant. My experimenting is just aping what I think may work and see ..hear if there is a change. ..welcome to my ears or not...

 

Here's a picture for your viewing pleasure.... I didn't replace the Caps with Duracell batteries BTW.....

 

 

 

Will let you know if I think there is a change...

 

Kind regards

Dave

 

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[Cornan]

Could RF resistance be an asset in certain uses such as analogue interconnects?

 

R

 

I would'nt know. My tablet descided to make fun of me putting an rf in front of resistance. I guess you want to extend that happy moment?

 

 

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[Middy]

From adding RF EMI shielding to my Sbooster's Transformer. Caps ....at least subjectively I feel it worked... I will write an Email to the company and ask if they feel the same if they try in a similar vein....

I will try to get some Objective data from a friends Oscilloscope in work.

The new power thread is having a bit of a "power struggle.".. So I am at a loss to what testing should ask my friend to look for....But at least I have made the shielding removable .....

 

Subjective win on power... Sbooster transformer

Subjective win on the intona ....

 

 

 

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[Cornan]

From adding RF EMI shielding to my Sbooster's Transformer. Caps ....at least subjectively I feel it worked... I will write an Email to the company and ask if they feel the same if they try in a similar vein....

I will try to get some Objective data from a friends Oscilloscope in work.

The new power thread is having a bit of a "power struggle.".. So I am at a loss to what testing should ask my friend to look for....But at least I have made the shielding removable .....

 

Subjective win on power... Sbooster transformer

Subjective win on the intona ....

 

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Nicely done with those copper taped caps Middy! I am happy it turned out to be a (subjectively) good tweak! I guess that copper cover also reduces some (minor) vibrations as well which is a good thing. I do not know if caps are perticularly sensitive to RFI/EMI. Caps is in general a very limited part of my "knowledge-bank".

[semente]

I've preferred my single-ended unshielded ICs to a twisted-pair and a BJC LC1.

It appears to sound "clearer" and also "cleaner" and more extended in the top.

I'm using 20cm mono-conductor Teflon-insulated thin solid core wire, parallel and distanced 10mm with a single return wire between the two live ones and the custom-designed amplifier uses optimised grounding.

I don't get any hum and the tweeters are hardly whispering at full power with ear near tweeter in normal conditions, or even with the phone over the cable, I must try with an electric motor.

Cost me less than £5 including the time it took for soldering.

 

R

[Cornan]

I've preferred my single-ended unshielded ICs to a twisted-pair and a BJC LC1.

It appears to sound "clearer" and also "cleaner" and more extended in the top.

I'm using 20cm mono-conductor Teflon-insulated thin solid core wire, parallel and distanced 10mm with a single return wire between the two live ones and the custom-designed amplifier uses optimised grounding.

I don't get any hum and the tweeters are hardly whispering at full power with ear near tweeter in normal conditions, or even with the phone over the cable, I must try with an electric motor.

Cost me less than £5 including the time it took for soldering.

 

R

Very interesting semente! So you mean that if I for example use solid core gold silver Mundorf wires with a distance between data+ and data- on my USB cables this will improve things from twisted wires? It would´nt surpice me since there is a capasitive coupling along the lenght of the wire even with the data wires. I just assumed the twisted wires would minimize EMI and that it was unnoticable. Will be interesting to try though since it is completely in line with my kind of thinking with cables! As soon as I have the time for it I will see if unwinding the data wires on my Elijah Audio Konvertible Lite will make a difference or not.