Shielded vs. unshielded Ethernet and Grounding

[asdf1000]

Hey @Miska

 

Is this stuff unshielded? There's no mention. But can you tell by the specs mentioned?

 

Cheers

 

 

[asdf1000]

While I'm with the unshielded ethernet group, I was looking through an Icron user manual and noticed this:

 

 

http://www.icron.com/pdf/el5363-hdmi-usb-2-0-manual.pdf

 

They have quite a bit of experience in both networked audio AND video, so there must be something to their recommendation, especially their notes on interference?

 

They're obviously not fans/believers of the balanced and isolated nature of unshielded ethernet.

 

It doesn't change the fact that shielding may open the door to a ground / leakage loop but they must have seen/measured this interference they mention.

 

I'll tag the respected experts @JohnSwenson @Miska @mansr @jabbr

[asdf1000]

51 minutes ago, mansr said:

I don't think that device uses Ethernet signalling, so there's that.

 

But it's HDMI video and USB 2.0 audio, over ethernet? A LEX and a REX unit.

 

http://www.icron.com/products/icron-brand/kvm-extenders/cat5/el5363-hdmi-usb-2-0/

 

 

[asdf1000]

22 minutes ago, jabbr said:

leakage currents can flow either through the shield (aka ground loops) or through the higher impedance of the PHY (parasitic capacitance of the ethernet transformer).

 

Hi jabbr. John Swenson has stated that he's had to build very customised testing gear to show the latter. Does your testing gear show the same or are just going off what John has said?

 

I have a lot of respect for John S btw, but just like to get an idea if anyone else has the means to easily see these things themselves.

[asdf1000]

27 minutes ago, jabbr said:

but does this matter?

 

Well yes, I would assume you've verified everything you say? Not that I need to see any measurements but I would have assumed you've verified with your own eyes, for yourself?

 

I mean this respectfully of course - not a personal attack. I've followed many of your posts and you are clearly a clever guy.

 

Some of us (me!!) blindly follow what the clever people say but I would have thought you'd have verified this high impedance leakage stuff yourself.

 

Anyway I don't want to harp on too much. It's really just the topic of the high impedance leakage sailing through digital isolators and ethernet's little transformers that interests me.

 

[asdf1000]

7 minutes ago, jabbr said:

Verified what? What I say about Ohm's Law?

 

No, you stated: "leakage currents can flow either through the shield (aka ground loops) or through the higher impedance of the PHY (parasitic capacitance of the ethernet transformer)."

 

The part in bold is John's claim (which I believe of course). I was just wondering if you've verified this claim with measurements yourself or just assuming it's correct.

 

 

7 minutes ago, jabbr said:

What levels of leakage currents might be significant in audio circuits?

 

(I haven't verified the answer to this question with measurements).

 

Ok, no worries at all then.

 

[asdf1000]

2 minutes ago, mansr said:

As those are the only paths available, the statement is trivially true.

 

Noted, but before John Swenson mentioned it, I'd never heard anyone talking about high impedance leakage currents sailing through ethernet transformers... 

 

Until then, only the shield path was really discussed.

 

So I was kind of asking if jabbr had actually seen what John S is talking about there... i.e. his own measurements.

 

But that was all cleared up above.

 

[asdf1000]

2 minutes ago, mansr said:

Probably because nobody else uses meaningless terms like "high impedance leakage current."

 

What was the old equivalent term/s before that?

[asdf1000]

36 minutes ago, mansr said:

Terms for what?

 

High impedance leakage currents.

 

I'm assuming if it was known before, it had another name?