Shielded or Unshielded Ethernet Cable

Anyone who recommends Ethernet over mains in an environment where we are interested in audio quality and impacts of RFI can not be taken seriously. And anything that an  organisation/company/person says should be treated with care and caution if they advocate such techniques. One can't ignore the physics of our famous founding scientists such as Hertz and Maxwell even it's inconvenient for the marketeers. Convenience doesn't have to mean putting up with possible health risks and possible sub optimal audio performance. (Sorry I get quite emotive on this.. ethernet over mains in domestic settings is one of most ludicrous technologies I have come across and where additionally contempt appears given by most of the organisations pushing the technology to the side effects caused - all in my personal opinion of course)

Mike is right some domestic  broadband  router switch  ports are poorly designed and can cause issues with TCP streams and multicast packets used in UPnP / DLNA as well Airplay applications. A dedicated consumer switch seems to mostly alleviate these issues and avoid any complications.

From a KIS perspective I would second Mike's diagram..

Simon

+1 & then some

Both the Chord Company and Chord Electronics web sites make reference to the use of ethernet-over-mains:

Chord Electronics “ethernet-over-mains connections can also be used if required” re: DSX1000 Reference network music player.

Chord Company “We also noticed differences in a system where the Ethernet signal was carried over mains wiring (not our recommended way of getting the music into your streamer”. re: New Chord Ethernet cables.

Make of it what you will.

Dave

Ethernet over the mains is really a last resort and i'm sure from a convenience point of view it's a neat and quick solution. It's a nasty technology though and not something i'd entertain in this house. Given the tight EMC specs we need to design for these days, i'm still amazed that legislation to allow powerline communication was ever allowed through 

+1, It's allowed because of an influential group of vested interests.

Originally Posted by james n:

Ethernet over the mains is really a last resort and i'm sure from a convenience point of view it's a neat and quick solution. It's a nasty technology though and not something i'd entertain in this house. Given the tight EMC specs we need to design for these days, i'm still amazed that legislation to allow powerline communication was ever allowed through 

+1, It's allowed because of an influential group of vested interests.

And exactly who is this influential group of vested interests?

Dave

I saw a group of string-vested interests at Margate the other week.

This body seems to cause a lot of disruption and has had a lot of lobbying power within the EU

http://en.wikipedia.org/wiki/H...g_Powerline_Alliance

Simon

or even: http://www.homeplug.org/

déjà vu I think. 

Dave

My experience with CAT7 has bought both gains and traps.  

I suspect the gains come from the improved conductor balance specifications and physical construction stability, as much as the shielding.

 The traps come from extending the ground plane of your system to digital components carrying noise currents (eg end-to-end to NAS), and/or accidentally introducing a second low- impedance grounding path at audio frequencies. This can be exacerbated when powered units straddle two spurs as I accidentally did and lost my top-end sparkle. So it needs a careful mapping of what-connects-to-what, and what-is-powered-from-where. In this respect, SMPS can be more forgiving than linear supplies.

For a really informative and easy-to-read backgrounder I recommend

audiosystemsgroup.com/RFI-Ham.pdf 

In regard to Mike-B's useful diagrams, consider also the 'DC' line from a switch's wall-wart to the switch as critical, assuming a standard domestic or lower-end unit.  I found a choke on a GS605v4's feed (10 turns of the DC wire around pliers was all I had to hand!) removed a distinctive edge to the harmonics.   It brought similar benefit to a linear supply.  A proper multi-turn LF ferrite in this position should be very effective.

I'd now be cautious about CAT7 end-to-end. A section of CAT6 UTP somewhere is automatic galvanic isolation! Conversely, linear PSUs can introduce lower-impedance ground linkages than SMPS.  Be careful with the combinations.

Thanks Simon, that was the lot I was thinking of, but I couldn't remember their name.

A multi-turn ferrite IS very effective on SMPS DC lines

I have them on all my SMPS that are associated with the audio power supply & that includes the phone & broadband on a power strip thats on the same supply.

And also on the AC side of the supply,  the SMPS switching noise is radiated in both directions.    

I use a ferrite clamp and wind the DC cable from SMPS several times through the clamp then click shut... that is a very effective choke and small and neat.

not sure about limiting to LF... in radio RF parlance LF is usually considered < 3MHz and there is quite a lot of crud above this upto 100~150 MHz I would want to attenuate.

Simon

I believe it gets a bit complicated as some of the broadband ferrites (normally considered usable 3-300MHz)have higher LF permeability than than some of the LF (500kHz - 60MHz) ferrites.  Hence, on a volume for volume basis, they're more effective for RFI suppression, even when used below 1MHz.

How about this:

I configure my VM Super Hub to modem only mode and connect a NetGear R7000 nighthawk (has shrouded metal ethernet ports) to it using a Chord C-Stream. I then connect the R7000 to the SuperUniti using another Chord C-Stream. Lastly, I connect a portable USB 3.0 HDD to the R7000 and use the R7000 media streamer to stream my Apple Lossless files on the HDD to my SuperUniti.

Is it sensible to use Chord C-Stream (shielded cat7) in the above scenario?

OK, update:

I'm now working on the copy and diagrams, and I've contacted a friend who's a competent graphic designer to work on the Web Site presentation.

Thanks to all for their efforts and contributions - especially useful for the inexperienced such as myself.

Just an update. I decided to buy the R7000 and Chord C-Stream cables and give them try. I connected a WD Elements USB portable drive to the R7000. I put the Virgin Media router into modem only mode and connected the C-Stream cables as described in my previous post.

To my relief it all appears to be working well. I'm using the media server built into the R7000 (ReadyDLNA) and it indexes and streams my apple lossless files (iTunes library) from the connected USB drive to my SuperUniti perfectly with no problems so far. I perceive the SQ to be an improvement from before, however, this is entirely subjective. I'm very happy with the results and can now get lost in the music (Damien Rice, 9 Crimes was a great place to start) rather than worry about whether my ethernet cables are shielded or not.

Chord did verify that in their own testing they found that as long as the shield was correctly terminated they got consistently better results with shielded cables, hence C-Stream is shielded.

All the best.

Just an update for those following - I returned the R7000 as I was having problems with it, the backup to the connected USB drive was failing - when attempting to restore files Windows informed me the file was corrupt.

I also returned my Chord C-Stream cables after returning the R7000 as my conclusion from the information that I have read is that you need to be some sort of electrical/electronic/network engineer to make head or tail of matters. It just seems safer to use unshielded.

I have reinstated initial simple setup of VM hub using Belkin Cat 6 unshielded. I have though introduced a simple unmanaged network switch to separate the SuperUniti and NAS from the VM hub – thanks to Mike-B for the advice. Difficult to say if sound is any different or not, almost certainly not noticeable. At the end of the day, it sounds good whatever.

All the best.

I hope the forum chat about Cat7 & grounding has not caused you to return the C-Stream. It is quite simple  once you get under the techno-babble

C-Stream between US & switch cannot be a problem. Add an unshielded section from switch to NAS & its 100% OK.   

OK, it sounds as though, in my guide for streaming networks, I need to add some potted solutions for using shielded cable.

Unfortunately I can only cover a few specific circumstances, not solutions for every conceivable permutation.

Huge, when you develop your guide I really would advise you steer away from shielded cables..they really are not needed in the home environment and appear to cause a lot of unnecessary confusion and complication for those starting off.. ( to do it correctly is more involved so as to avoid earth loops) And I am sure a lot of it is consumer marketing bling..

They can be added as a tweak for later on if wanted and when the use has become a little more proficient.

Simon

Simon I agree that shielded is not required in home environment, but you might be treading on toes with those who have already gone down that path & with some exotic (expensive) stuff & I would be concerned about not saying something could go against the acceptance of Huge work. 

My experiments & changes this week (posted in the “Chord Ethernet cables” thread) have proven to me the negative effects of more than one ground.

In my case I had 2 grounds running on the same power circuit & adding an RJ45 M/F UTP connector on the 2nd ground point (NAS) was £5 well spent.

(Huge I did not elaborate on this) but I ran an experiment with an extension lead from the ring main that includes kitchen, utility & heating to temporally power the NAS; the change with & without the UTP dis-connector was a lot more than slight. 

To the point about marketing “bling”,  100% agree – words of wonder & little or nothing else – I won’t get into the way some of these cables are constructed outside ISO/IEC 11801 standards.   But saying nothing risks joining in another cable debate,  whereas unlike the yeh’s & nay’s & need for golden ears & deep pockets over power, speaker & IC cables,  Ethernet cables do have a real technical reason in their network application.  

Simon, essentially I have done that, it starts off with UTP, then UTP with ferrites, then goes on to mention STP but warns that it gets a lot more complicated because of earth loops!

Simon, Mike, In the Padded Cell thread, I've just posted a link to a PDF version.

Mike,  That result using different earths isn't exactly unexpected (I'm sure it wasn't for you either), but as the empiricists say "One should not place too much faith in theory until it's confirmed in practice.": So a very useful test.

There again the theoreticians say "One should not place too much faith in practice until it's confirmed by theory."