79 replies to this topic

[Mike Gillespie]

EMI/RFI paper has come up as an issue in the Jplay forums before, but never in one spot that's easily accessible.  Kyrill had some great comments to make in Marcin's mega-thread about building a Computer Audio that ran over 300 – 400 pages if you printed it.  (I know because I once made the mistake of trying to print it and read it and it was 300 pages way before the thread kind of died out).

 

I would like this thread to become a simple place to find the best information from the forum audience. 

 

I'm only bringing this up now, because many of us are again considering using EMI/RFI paper but we don't know how to use it (really where to put it for best effect).

And it's extraordinarily expensive — up to $120/sheet U.S. for SOtM, and easily $70 per sheet for the 3M 5100S paper. 

If those of you who've already experimented with this paper can share their photos and advice here, I'm sure many of us would appreciate it.

 

Also, if you had negative results, that would be good to know as well.

 

I've never posted photos here…So if someone knows how, that would also be helpful.

 

Thanks.

 

Mike

 

===================

Here are some tips from emails I've got: 

 

From Marcin: "There is no need to paste it, works the same" (if you just put it on the surface)

——————-

Audiophil's: 

Here is a link to Audiophil’s Dac photo and memory photo:

https://twitter.com/...3543168/photo/1 , https://twitter.com/...5223040/photo/1, here is the link to some pics of Sotm and what they say to do for treating a CAT: http://sotm.godo.co.........=186785451

Edited by Mike Gillespie, 19 October 2013 - 05:49 AM.

[Mike Gillespie]

Here is advice that Kyrill contributed to other threads that I'm putting for convenience here:

 

"On the mother board as Marcin suggested put it "everywhere"  against the memory coolers, strips on top and alongside the coils which as a set belong to a strip of Voltage regulators (VR), on top of the VR,You can see such a strip near the memory bank and near the CPU and there can be more, Yes on the CPU and ground the cooler of the CPU put 2 strips on top of each other and alongside ( small strips) the clock( s) on the motherboard. Clocks especially broadcast RFI in spite of their little metal housing. Also glue strips along side the lanes getting to clock. The idea is to put a strip on top of the lane which is the output of the clock as it is a broadcasting  antenna of the clock  and is not shielded. Choose also all  the bigger chips or put a sheet  that covers a big part of the motherboard.

If inside is also the (swps) digital power supply ( better is it to place it outside and out of sight of the beautiful PC enclosure (enclosure must be aluminum and not steel or iron, but most are aluminum) the swps must be "buried" in those sheets

A whole sheet underneath the motherboard unless it is wood. If you are young, eager and enthusiastic, do it in small steps. Listen after every step. make notes. Listen at least 20 minutes to get the "gestalt" of the sound, then proceed with the next step, listen, make notes and so on. Especially the notes will contribute to this forum

A primary condition for this (young) researcher is that NO digital garbage leaks back via the powerchord of the digital device into the powerline that feed your analogue stereo setup (preamp and or poweramp or integrated) if you use one.


Take the thickest sheet with better damping properties. I think it is 1mm. I would buy the combined RFi/EMI sheets, or as separate sheets

their freq range is broad so that is a plus, the broader the better as I dont know in which freq range  PC motherboards RFI domain is.

buy 1 sheet first or 2,  one for each type and experiment first  if you hear a difference. My  setup is developed to be very transparent. I hate  opaque sound-fields. so now differences in gear and recordings are multiplied. I have no crossovers. woofer, mid and highs are directly coupled to the amplifiers, all cross overs are digital with almost zero phase differences (DEQX)  Every component (dac, amps, preamp) all have their own dedicated line conditioner so no interference between components .Other setups may have other advantages but be less transparent,so differences in hot rods or closed enclosures or with or without 3M sheets are harder to discern.

 

A standard sata cable is cheap and bad it is an internal antenna which picks up all generated HF garbage within the computer. Know why you cannot phone within an airplane? If tens of ppl would use their mobile phone approx at the same time when connecting the aluminum  fuselage of the aircraft would reflect  that connection spike  back into the plane itself a too big amount of the generated RFI which may interfere with sensitive components of the plane. The aluminum case of for instance a PC is a very good reflector  keeping all the RFI garbage inside the enclosure. A hot rod does not have that problem but has external RFI and EMI drawbacks. Still much less ugly micro vibrations

 

The difference between my (still) hot rod and a laptop was huge but also because of the 5V clean linear power to the hard disks which is not possible in a laptop. my motherboard is connected t wood.

"As you noticed, there is a piece of wood inside every DAC chassis. It is not a decor and it is not some mysterious voo doo element. We simply discovered strong dependency between the sound quality and the proximity of grounded steel planes to the DAC chip. That means that if the DAC chip "sees" a steel grounded object in the proximity of say 10 cm – it will somehow choke the sound. Without solving that mystery scientifically – we decided to remove the steel floor from underneath the entire PCB and replace it with a nice wooden flooring. For the same reason we  eliminated the steel top cover and replaced it with aluminum one. The music flows free and unrestricted.  Magnetically speaking, the DAC pcb is floating in the air. "  (Lucas Fikus)

I expect a SSD  outside the computer with its own aluminum (earthed!) dedicated enclosure* with emi sheets inside or glued to its outside    feed by a shielded high end silver sata cable ( also emi shielded) will sound better than with a  USB/SATA converter in between. *not its own enclosure protecting its innards.  Direct and simple connections sound mostly better than complex ones. Analogue interlinks sound better the more they are shorter. This is NOT true for digital interlinks. ( Steve Nugent/Emprical audio) reflections in the cable need a certain time frame to run behind the original signal, in order not to become intermixed with it and fuzzy the sound. His rule of thumb, is 1.5 mtr but there is some variation depending on clock frequencies. SO make it between 100cm and 2 mtr. OR a direct link as short as possible, a sata cable of 8 cm or shorter, this will place the ssd + enclosure inside the computer.The 5V line for linear pwr to a SSD should in all cases be shielded too.



Last night I tested the 3M AB5100S EMI ($72) sheet against the ERS Stillpoints ($25). Money-wise is not a fair comparation,  but this is the 3M what Kirill recomended. Thank you Kirill. Wink

The difference is very obvious. With Stillpoints it was a compromise, clearer mids, but sucked highs! The bass was boomy also. No life.

With 3M everything is clearer, more transparency and much better, tighter bass. Bass is one of the things that I did not expect to improve that much! With 3M is only a benefit, witch is very rare with the tweaks.

In my opinion it's definetly worth the money and I will go with 3M.

Now there is another question what bugs me: How will sound the different 3m sheets? Frown

I guess that we can't have an answer for everything, and probably different sheet will perform different in depending on place.

Screenmusic I bought the 3M sheets from here: http://www2.mouser.c...ct.....hGlXGlU=

Again, thanks to Kirill.

 

I bought 3 sheets (free shipping) and I tried them everywhere, on top of my PC-Mini, on top of my DAC, on top and under my big amps transformers. The results where the same. This was just a quick experimentation.

[stoneman]

Gents, this is very interesting. I've ordered some 3M sheets, but what's also interesting is whether replacing the base of the PC with wood would provide benefits? I note the point about DACs in particular; I use two Lyngdorf TDA 'power DACs' perhaps these would benefit from wooden bases? I'd intended to replace the top of my PC cases with thick aluminium sheets - primarily to make my PS Audio Power bases work, but it seems they will also improve the RFI? Regards Andy

[ellisdj]

Just ordered a sheet of 3M 5100s to try out - going to put it on my ram and riser card cable to start with it to see what if any difference it makes.   Is it essential to remove the heat spreaders from the ram - or will the paper still have the desired effect placed ontop of the heat spreader?

[RubenV.]

Awesome thread Mike /wp-content/forum-smileys/sf-cool.gif Very helpfull! Thanks.

[AudioPhil]

Hi

 


This is my Mytek DAC with SOtM eABS-100.

 

[Mike Gillespie]

Phil,   Thanks for posting that photo.    Some closer shots would also be great to see.

[Sligolad]

Meitner MA1 SMPS lined with the 3M heavy stuff....it certainly does not allow my AF Camera to focus on it!!!

[Mike Gillespie]

Pearse, thanks for posting it. On the bottom, is that just a whole sheet laid down?   And on the SMPS, how did you choose what to cover?  Will help all of us to get some hints.

[Sligolad]

Sorry messed up link to one of the pics and cannot edit original post so here is a pic of the bottom again.

I just cut strips for all the faces of the Power Supply housing internal walls.

[Mike Gillespie]

Remember, Group 3m 5100S Buyers... (and others) share your results by posting photos here... to help us less tech-oriented.   Thanks.

[item]

We have some experience using shielding/absorption materials. There are some pictures of an SoTM-fettled PC  here: http://www.itemaudio........sheet.html

Some of this overlaps the group buy thread, so apologies.

It's pretty frustrating to try deploying random bits of highly expensive material in dubious sizes and locations without understanding precisely what/why you're doing (it)! Lots of trial and error.

Any box that produces a tuned analog frequency response (DAC, preamp, amplifier) has been fettled for a desired frequency response in that case - allowing for the enclosure and conditions inside in. Most such components sound different when played cabriolet for that reason: EM/RF radiation bouncing around internally has to some extent been factored in to the design and corrected for.

So when we march in scattering EM/RF absorption, it's not always a good thing. We're as likely to put a wet blanket on the sound as clean it up. Successful internal application tends to be minimal and judicious. When Rick Cullen modified the PS Audio DAC, he used just a couple of square inches of Stillpoints ERC fabric on the case around the 'reflection point' of the IEC inlet.

Tricky business.

Also important to release that Stillpoints ERS, for instance, is mainly effective as shielding, but isn't thick enough to be useful at absorption of lower Gigahertz frequencies. And when you attach it to a metal case, it's adding nothing to the shielding characteristics of the case itself: in fact, it's rather hard to imagine how putting a sheet of of such material on top of a metal case would do anything at all - other than perhaps to plug screening gaps created by ventilation slots or holes, which may allow stray RF to beam into the case. Attaching it to a power cable or plastic mains outlet may provide useful shielding where there is none, however.

Overall, if it's worth using, it's probably worth using heavier gauge, more wide-ranging materials than Stillpoints cloth - such as the 3M 5100 series and SoTM aBS100 - unless you're tackling a specific 2-10GHz issue that isn't too serious, or are on a tight budget. Stillpoints ERS is cheaper, but has bare conductive edges and is pretty friable: we've fritzed more than one board with a rogue fibre. We nowadays tend to tape the edges.

Some pictures here: http://www.itemaudio........sport.html

Crucially, though, computer transports aren't producing analog output. We don't need to worry about tailoring a frequency response or spoiling a pre-set balance. We're looking only to tame and contain the white noise melée of RF radiated by the board and its power supply that will otherwise bounce around the case and feedback into signal paths. The more absorption you use, the quieter the electrical environment of the case and the closer we reach the holy grail of the computer delivering 'only noughts and ones'. It's hard to see (and hear) how you can overdo absorption in a digital device.

But assuming you don't blanket the entire apparatus, bankrupting yourself and overheating the PC, where best to deploy the stuff? First - exactly as you would when trying to mask a light-bulb to reduce lux levels in an enclosure - tackle the most energetic sources first: the area around the processor, power input, switching regulators, memory, PATA & ATX interfaces. Second, the USB output. Third, the reflection point. Finally, everywhere else.

[stoneman]

Hi item, can you explain reflection points please? Ta Andy

[stoneman]

I meant to add... I`m not especially technical, but it strikes me that absorbing RFI will have most benefit where it can firstly prevent radiation into the case, then where it prevents stray radiation entering a sensitive component and lastly in mopping up stray effects in the case, is that correct? Ive used a sheet of the 3M stuff in each of my PCs trying to follow that logic but to be honest, the effect was minimal. I`m content with it as a 'just in case' (excuse the pun) ploy and as a fun exercise What I did find extremely beneficial was sheilding my DC lines, and I suspect a certain amount of the PPA SATA cable improvement is due to their sheilding too (Paul confirmed they're shielded to me). In my mind's eye at least, these important carriers are now effectively 'outside' the case and therefore avoid the RFI altogether. Following your advice, I think I probably have a few bits of 3M doing very little – I will try putting them on the unsheilded SATA and power connectors Regards Andy

Edited by stoneman, 16 November 2013 - 11:41 AM.

[Mike Gillespie]

Guys, for those of you who have used the 3M paper before, please help those of us who haven't.  Please update the thread:

 

http://jplay.eu/foru........38;ret=all

 

Can the guys who've used EMI/RFI paper (SOtM, 3M, etc.) post photos here of how you did it?

 

PHOTOS and some hints would be so appreciated.

 

Thanks.

[kyrill]

AudioPhil said:

Hi

 

This is my Mytek DAC with SOtM eABS-100.

 

I take this picture as a nice example of how most people 'glue' their 3M on top of chips while you can see that the legs of the chip are still bare. Better protection is if you cut the piece of 3M a bit bigger so it covers the legs as well if after all the little bits and pieces of cuts you still have some spare 3M parts, double the layers as they add to each others

 

there is no reason not to cover 'things' which are not chips on the board, stray RFI reaches everything; 

especially aluminum cases reflect stray RFI very well. the "E" part of EMI. So cover at least one wall of each side and the top. Two parallel reflectors are like two mirrors and reflection will going on many many times until it dies out. 

The designer of lampizator dac Lukasz Fikus found that a metal plate (underside enclosure) to close to the board or components have a negative effect to the musicality of the sound unless d=> 6cm+. So he replaced it with a wooden plank ( in one of his versions) First,  wood does not reflect or induce EMI, it has a very very pleasant resonance frequency of its own compared to metal or stone or plastic, imagine a violin o of aluminum or plastic how it will sound …Its drawback is it pass thru RFI and magnetic fields of other sources.

So as the 'floor' of an enclosure it will do wonders if you live on ground floor level. Not higher or you use lessemf.com sheets underneath the wood with a 3M 5100s sheet in between. that is what I did with my PC

 

By now I have expressed my enthusiasm for the AVM paint very clearly. if you think the paint is a risk to yr treasured dac pc or amps then paint the 3m sheets pieces before you cut them,

Paint them while they are firmly pressed to the components: Firmly pressed. Then paint the piece. It will 'magically' damp the always present micro vibrations and you will hear it. but, yeah..it will sound better if you paint the whole underside of the boards and so on as instructed by avm.

Edited by kyrill, 14 February 2014 - 12:00 PM.

[item]

stoneman said:

I meant to add...

I`m not especially technical, but it strikes me that absorbing RFI will have most benefit where it can firstly prevent radiation into the case, then where it prevents stray radiation entering a sensitive component and lastly in mopping up stray effects in the case, is that correct?

Ive used a sheet of the 3M stuff in each of my PCs trying to follow that logic but to be honest, the effect was minimal. I`m content with it as a 'just in case' (excuse the pun) ploy and as a fun exercise

What I did find extremely beneficial was sheilding my DC lines, and I suspect a certain amount of the PPA SATA cable improvement is due to their sheilding too (Paul confirmed they're shielded to me). In my mind's eye at least, these important carriers are now effectively 'outside' the case and therefore avoid the RFI altogether. Following your advice, I think I probably have a few bits of 3M doing very little – I will try putting them on the unsheilded SATA and power connectors

Regards
Andy

Most SATA cables are shielded, but most DC cabling is not - so copper-foil treating and insulating cabling in the case is always a good idea. We use such cable universally in our ATX looms for the three-rail supplies.

In the Mac Mini mods, and the T1, we always aim to put the absorption material as close as possible to the noisiest components: always underneath the motherboard, around the ATX power input, on both sides of RAM (unless it has a heatsink), and sandwiching the Adnaco or SoTM output card.

[SIMA66]

I will have about 3 feet (1m) long DC cables from my Power Supply to my Zuma. The question is what and how will be the best way to shield this cables against EMI?   Would it be better to use a grounded copper mesh (or something different) and shield the + and - together or separately? Should they be twisted around each-other? What should I do and what should I avoid?   Any other thoughts or ideas are appreciated.

[kyrill]

if you make yr own cable as it is so simple, 1) use occ copper, with teflon or pure cotton sleeves. dont shield them apart, but twist them, 2-3 turn per inch. 2) then do cotton wool loosely around it to enlarge the distance between wires and shield, the more the better. Dont press the cotton wool, the more air is trapped, the better'. This will enlarge the diameter of the construct, 3) wrap RFI/EMI absorber ( carbon based foil) around it but dont press the cotton and fix it in place at the end with tape. 4) Repeat with RFI blocker like Ripstop  fabric (lessemf,com). or 3b) replace 3) with very thin teflon tape (used by plumbers) and 4b) shove it gently through a bigger diameter teflon tube, now it is firm 5) do copper mesh around the teflon tube or one layer of carbon EMI absorber around the tube and the mesh 5B if  to close there are other power cables around with their strong EMI add one layer of foil including cobalt 6) finish with something to make it look fine  If you can ground the foil or mesh is even better The crux is to keep the metallic copper or copper silvered mesh as far as practical (!) distanced from the power wires That is what I would do

Edited by kyrill, 14 March 2014 - 06:17 PM.

[SIMA66]

Woooow, thanks Kyrill, that was more that I expected!   Where you can find, and what is the purpose of Cotton Wool from step #2? Dielectric ?