[jtwrace]

Can anyone tell me if this actually does anything of any benefit?  What would be inside?  Coils and transformers?

http://www.acoustic-revive.com/english/pcaudio/lan_isolator.html

This hobby is just crazy!  I see stuff like this and just wonder....

[randytsuch]

$250 at Amazon?

Seems pretty pricey.

Ethernet already has a transformer built in, so I'm not sure how this thing decreases the noise as they claim.

[AKLegal]

Most medical grade isolators are at least the size of an average male's wallet.  Yet this one claims to outperform them in a package that is barely larger than the RJ45 port itself.  I haven't tried it but I am skeptical that it outperforms *real* medical grade isolators or straight up ethernet EMI/RFI filters.

Its hard for a regular consumer to find medical grade isolators for easy one unit purchase.  These folks might be exploiting that fact since there wont be many people who can compare it to a real medical isolator.   

[highfilter]

Not sure about the Acoustic Revive, but something like the GISO, from what I understand, is basically just using higher quality transformers to isolate (eff if I know). I have no personal experience with the isolators, but I've read user reports that the GISO Isolator outperforms the Acoustic-Revive when compared directly.

Information on the more wallet-sized GISO isolator: http://www.acousence.de/index.php?option=com_content&view=article&id=253&Itemid=90&lang=en

[randytsuch]

If I was going to try to improve an Ethernet connection, I would consider getting an Ethernet switch, and buy or build a linear reg to power the switch, and then run the ethernet through that.

My 2 cents.

[mjock3]

Lan-Isolators do offer some improvement in sound. Not night and day but some.
I too have read some very good feedback on the GISO isolators. And what I have read makes me think it blows the doors off of the Lan-Isolator by Revive. Check out Jplay and see what some have said. None of them have any intentions of sending them back, but they are rather pricey.

[PeteG]

I have the Acoustic Revive on the way (didn't know about GISO), I will also get a linear PS for my router. Hopefully I will hear a difference.

[jtwrace]

Not sure about the Acoustic Revive, but something like the GISO, from what I understand, is basically just using higher quality transformers to isolate (eff if I know). I have no personal experience with the isolators, but I've read user reports that the GISO Isolator outperforms the Acoustic-Revive when compared directly.

Information on the more wallet-sized GISO isolator: http://www.acousence.de/index.php?option=com_content&view=article&id=253&Itemid=90&lang=en

What's the cost of this beast?

[mjock3]

I have the Acoustic Revive on the way (didn't know about GISO), I will also get a linear PS for my router. Hopefully I will hear a difference.

Yes Pete,  I plan on the linear PS as well. Looking forward to hearing the difference. I never would have thought that would make a difference but have read good things about that as well.

[highfilter]

What's the cost of this beast?

GISO-DS $331
GISO-GB $464

I know, ouch.

[kc8apf]

I'm really curious why they make a difference.  Ethernet uses differential pairs and requires transformers at both ends of the cable.

I took apart a MagJack (ethernet jack with built-in magnetics for use on PCBs) the other day to reverse engineer the pinout.  Internally, there were two transformers: one for each differential pair.  The wire side of the transformer is a normal 2 wire connection while the PCB side uses a center-tap configuration.

The transformer is designed to pass 100BaseTX which signals at 125MHz.  That certainly could cause system noise but you can't filter it or the Ethernet wouldn't work.  Grounds are not tied unless you are using shielded cable.  That doesn't leave many options for passing noise from the cable to the PCB.

I'm certainly willing to believe these isolators make a difference.  I'd just like to understand how.

[jtwrace]

GISO-DS $331
GISO-GB $464

I know, ouch.

Thanks.  Yes, ouch!

[ted_b]

Can anyone tell me if this actually does anything of any benefit?  What would be inside?  Coils and transformers?

http://www.acoustic-revive.com/english/pcaudio/lan_isolator.html

This hobby is just crazy!  I see stuff like this and just wonder....

I love mine; best $229 I've spent in a long long time.  Same with several buddies I know.  In my setup it ists between my controlpc and my audiopc (which is a direct connection).  The dongle is going nowhere.  The overall solidity of the soundstage improves, as does the texture/tonality....and according to Priaptor (Dr Howie) he measured that the affected pc was getting a significantly more consistent ethernet data rate, which tells me its noise filters are working to prevent re-sending (i.e error correction).  That's all I know, but I've had plenty of tweaks that do nothing.  This isn't one of them.

Ralf at Acousence is a long time acquaintance, and I highly reocmmend his recordings to all out there.  His GISO doe not yet have a US distributor, so US evaluations from me will have to wait

[randytsuch]

I'm really curious why they make a difference.  Ethernet uses differential pairs and requires transformers at both ends of the cable.

I took apart a MagJack (ethernet jack with built-in magnetics for use on PCBs) the other day to reverse engineer the pinout.  Internally, there were two transformers: one for each differential pair.  The wire side of the transformer is a normal 2 wire connection while the PCB side uses a center-tap configuration.

The transformer is designed to pass 100BaseTX which signals at 125MHz.  That certainly could cause system noise but you can't filter it or the Ethernet wouldn't work.  Grounds are not tied unless you are using shielded cable.  That doesn't leave many options for passing noise from the cable to the PCB.

I'm certainly willing to believe these isolators make a difference.  I'd just like to understand how.

I think the actual bitrate for 100baseT is more like 25 MHz.  125MHz is the signal rate.

And you can EMI filter fast signals, they have EMI filters for even faster things like USB.  For example, Common mode chokes can be used. 

Now I wonder what they are doing inside these things?

Like I said before, Ethernet has to be transformer isolated. And there are definitely limits to what you can do before you degrade the signal.  There is something called an "eye diagram" which can be used to measure the integrity of ethernet signals, but you need expensive test equipment to make these measurements.

Randy

[kc8apf]

If you don't care about the details of Ethernet, skip ahead.

You're right, 125MHz is the symbol rate.  25MHz is the clock rate for MII (the 4-bit wide interface from the MAC to the PHY).  The PHY applies 4B5B encoding to the MII data to get the 125MHz symbols rate.  For 100BASE-TX, MLT-3 is then applied which keeps the same symbol rate but causes the fundamental frequency to be a quarter of the symbol rate (31.25MHz).

So, EMI filtering can be applied to filter signals above 31.25MHz.  A common-mode choke could do that but I'm not sure what that really buys you.  There are no shared power signals in Ethernet so you won't see noise from the other side's power supply.  I just don't see much noise getting into the system via Ethernet that you can actually filter.

USB is a bit different since the power rails are frequently connected and the data signals are directly attached.  The wire encoding (NRZI) also causes frequency to track the # of consecutive 0s.  For USB2 that means you need to handle up to 480MHz.

[jtwrace]

Is there anyone on this forum that's in the medical IT department?  What LAN isolator's do you use? 

[skunark]

Ethernet isolators for medical use are only designed to stop any leakage current to flow to a patient in the event of a device fault.   In other words, an additional CYA safeguard to prevent shocking a patient because of some random failure.   These isolators aren't designed to reduce RF or reject noise, etc..  In general ethernet is pretty low noise to begin with, but if you are concerned switch to fiber.

You can put this in the same camp as a "usb isolator" that they have to connect the ground, which by definition isn't isolated. 

[skunark]

I slightly find the silence of this thread interesting since I pointed out that the medical isolators for ethernet were not remotely designed to do what was originally thought.   

Effectively the *cough* medicial Lan-Isolators are no more useful than wrapping tinfoil on the bunny ears to improve reception.    Yes i'm poking at the fire (for the best $xxx spent) but between the magical 15 ohm resister sold for hundreds on the nickel and threads like this, there's a lot money to be made on false hopes. 

Keep in mind that I only stated the requirement for medical ethernet lan-isolators, not that they performed as well as aluminum foil wrapped around the bunnies of your BW TV... 

Jim
George Straight - Ocean Front Property

[Hank]

Nicely pu, Jim.

[randytsuch]

I slightly find the silence of this thread interesting since I pointed out that the medical isolators for ethernet were not remotely designed to do what was originally thought.   

Effectively the *cough* medicial Lan-Isolators are no more useful than wrapping tinfoil on the bunny ears to improve reception.    Yes i'm poking at the fire (for the best $xxx spent) but between the magical 15 ohm resister sold for hundreds on the nickel and threads like this, there's a lot money to be made on false hopes. 

Keep in mind that I only stated the requirement for medical ethernet lan-isolators, not that they performed as well as aluminum foil wrapped around the bunnies of your BW TV... 

Jim
George Straight - Ocean Front Property

This thread is a year old, so I wouldn't read much into the lack of response, I had forgotten about it.

Since I haven't tried it, I won't comment on if it helps or not, I don't have any first hand experience to relate.

BTW, there are actually USB isolators that do isolate the grounds, but they only go up to full speed, Analog Devices makes the chip.
http://www.analog.com/en/interface-isolation/usb-isolators/adum3160/products/product.html