Ethernet - Galvanic Isolation

soundcheck · 28th October 2009, 09:21 AM

Hi folks.

We discussed USB isolation recently over here. Though I don't think ethernet isolation has been discussed so far.
The subject I'd regard almost as important as USB isolation.
If you -- I do -- run a wired home network, you'll for sure generate pretty awful groundloops. These might have a certain impact on your audio performance.
Your file server usually does not sit on your clean audio power rails - you actually don't want them in the audio environment.

By default the ethernet ports are isolated with transformers. However - ground loops from shielding still exist.

We all know what polluted grounds can do to the system.

The question is now what's the best way to get rid of them.

1. Take off the shields/grounds from the receiving end
2. Commercial Isolators (Checkout the circuit drawings)
3. The DIY version of 2.

4. Anything else? It should be "affordable" - therefore no fiber and deliver "high performance" - therefore no wireless?

What's your opinion about the subject? Feedback welcome.

Cheers

Michael J · 28th October 2009, 09:52 AM

ethernet optocoupler - Google Search

That sort of thing?

wwenze · 28th October 2009, 01:27 PM

My home ethernet uses unshielded twisted pairs. What is yours using?

DigitalJunkie · 28th October 2009, 02:18 PM

FYI,most every ethernet interface *IS* isolated by small pulse transformers. Take a peek near the jack on a NIC,or router.
Consider long runs from one end of a building to the other..they already thought of that.

Shielding may be an issue in some cases,but it's not commonly used in residential settings.
Some equipment has it isolated with a capacitor,from the shield to earth/case ground-there shouldn't be any ground loops.If there are,lift the shielding at one end.

star882 · 29th October 2009, 01:05 AM

Isolate the audio with a fiber optic cable. That will work if you can use the digital output.

In my experience, interference is actually not very likely.

phofman · 29th October 2009, 11:20 AM

Shielded twisted pair (STP - unlike UTP) is a perfect cable for S-VIDEO

I have not seen STP used in larger network installations and I would be very surprised if people had their homes wired with STP.

28th October 2009, 09:21 AM	#1
soundcheck diyAudio Member Join Date: Mar 2005 Location: DUS Blog Entries: 1	Ethernet - Galvanic Isolation Hi folks. We discussed USB isolation recently over here. Though I don't think ethernet isolation has been discussed so far. The subject I'd regard almost as important as USB isolation. If you -- I do -- run a wired home network, you'll for sure generate pretty awful groundloops. These might have a certain impact on your audio performance. Your file server usually does not sit on your clean audio power rails - you actually don't want them in the audio environment. By default the ethernet ports are isolated with transformers. However - ground loops from shielding still exist. We all know what polluted grounds can do to the system. The question is now what's the best way to get rid of them. 1. Take off the shields/grounds from the receiving end 2. Commercial Isolators (Checkout the circuit drawings) 3. The DIY version of 2. 4. Anything else? It should be "affordable" - therefore no fiber and deliver "high performance" - therefore no wireless? What's your opinion about the subject? Feedback welcome. Cheers __________________ ::: Squeezebox Touch Toolbox and more ::: by soundcheck

28th October 2009, 09:52 AM	#2
Michael J diyAudio Member Join Date: Oct 2009 Location: UK	ethernet optocoupler - Google Search That sort of thing? __________________ *GONADS!* If ya got 'em, bridge 'em.

29th October 2009, 01:05 AM	#5
star882 diyAudio Member Join Date: Mar 2007	Isolate the audio with a fiber optic cable. That will work if you can use the digital output. In my experience, interference is actually not very likely. __________________ "Fully on MOSFET = closed switch, Fully off MOSFET = open switch, Half on MOSFET = poor imitation of Tiffany Yep." - also applies to IGBTs!

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28th October 2009, 01:27 PM	#3
wwenze diyAudio Member Join Date: Mar 2008	My home ethernet uses unshielded twisted pairs. What is yours using?

28th October 2009, 02:18 PM	#4
DigitalJunkie diyAudio Member Join Date: Apr 2003 Location: Portland,Oregon Blog Entries: 4	FYI,most every ethernet interface IS isolated by small pulse transformers. Take a peek near the jack on a NIC,or router. Consider long runs from one end of a building to the other..they already thought of that. Shielding may be an issue in some cases,but it's not commonly used in residential settings. Some equipment has it isolated with a capacitor,from the shield to earth/case ground-there shouldn't be any ground loops.If there are,lift the shielding at one end.

29th October 2009, 11:20 AM	#6
phofman diyAudio Member Join Date: Apr 2005 Location: Pilsen	Shielded twisted pair (STP - unlike UTP) is a perfect cable for S-VIDEO I have not seen STP used in larger network installations and I would be very surprised if people had their homes wired with STP.

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