Ethernet Noise: Proof Of Concept

From DJM Electronics:
The DJM Electronics FOIL™ brand Ethernet filters utilize patented technology and are the only EMI/RFI filters for Ethernet on the market that offer 100dB performance from 10kHz to 10GHz and higher. Housed in a single, convenient filter package, FOIL™ Ethernet Filters are the easiest and most reliable solution for bringing 10/100 and Gigabit Ethernet access to all varieties of shielded rooms and enclosures.

Standard signal line filters rely on capacitors and inductors to eliminate unwanted RF signals. However, these types of filters often eliminate the high frequencies that make up the sharp edges of high speed digital square wave signals thereby degrading the integrity of the signal. In order to avoid this side effect, it is necessary for standard signal line filters to have extended passbands that allow the higher frequencies to pass unimpeded. Even the best standard signal line filters offer only 70dB from 50MHz to 10GHz and will only work with 10Base-T. There are no Fast Ethernet (100Base-TX) or Gigabit Ethernet (1000Base-T) standard signal line filters available on the market. Also, it is important to note that standard signal line filters do not differentiate between Ethernet signals and undesirable signals. They act like a "hole" in the shielded enclosure to all signals - good and bad - within the passband.

Unlike standard signal line filters, FOIL™ Ethernet Filters utilize a fiber optic isolation link (FOIL) to maintain 100dB shielding integrity. The filter converts ONLY Ethernet packets, so there is no passband and no transmission of unwanted signals.

We guarantee that FOIL™ Ethernet Filters will not interfere with your network, increase hop counts or degrade network performance - a common problem with standard signal line filters.

I received an email from Steve McNally of DJM Electronics wherein he asked if I'd be interested in giving one of their Ethernet EMI filters a listen. I said, "Yes".

I'll be writing about the DJM Electronics GigaFOILv3 ($1,000) in the not too distant future.

Clever Dean's picture

I'll go fiber all the way. Test the EMP unit!

Michael Lavorgna's picture that it's more of a "proof of concept" than review since the GigaFOILv3 is not designed for home use. As you point out, there are less expensive solutions including fiber, but if the DJM product offers a clear improvement, the company may design a much less expensive unit for home use.
DH's picture

Acc'd to SOtM, their CAT 6 Lan Isolator "Our device contains 10GBASE-T Ethernet magnetics" and

"The 10GBASE-T Ethernet Magnetics is an Ethernet isolation transformer but the only one which supports the 10GBASE-T specs. Those are of much higher bandwidth/speed and less loss/noise than 10/100BASE-T, hence suitable for a far higher-quality LAN connection. Most isolation transformers can’t support Gigabit Ethernet. We use a CAT6-compliant RJ45 connector so the iSO-CAT6 fully supports the CAT6 connection. "

Michael Lavorgna's picture
...since DJM does not serve the consumer market, they are unaware of the SOtM filter.
PeterV's picture

Hi Michael,

In line with the positive experience with the jitterbug and other 'jitter-killers' I have been searching the web for solutions like these for ethernet cables as well. I've found products from acoustic revive and Acousense and ordered recently the Acoustic Revive LAN filter abd am currently testing it in combination with my 15 meter poor quality ethernet cable. It does have a positive effect on the sound quality, although not as much as the jitterbug with the USB stick I use. Maybe you can take a closer look at these products, even evaluate them?

Phil_C's picture

I wonder how the FOIL Ethernet filter compares to a tweak suggested by a presenter at the recent T.H.E. Show Newport who works for a large audio company. He uses a couple of Ethernet/optical cable converters to reduce noise created through Ethernet cable.

The converter is a Startech 10/100 Mbps Multimode Fiber Media Converter SC. But, he said several manufacturers offer this equipment.

The converter's purpose is to extend an Ethernet network over optical fiber cable, a way of bridging the two. But an intriguing byproduct, and of potential interest to digital music audiophiles, is noise is eliminated by going from Ethernet to optical cable. Kind of like a noise break in the signal path.

Imagine an audio signal going from a router and Ethernet cable into a converter, out to an optical cable and into another converter, and then out to a short length of Ethernet cable to its destination. An optical cable sits in the middle and this eliminates Ethernet cable noise. Or, if the destination device handles optical cable then only one converter is needed.

This particular converter costs about $65 on Amazon, so it seems like a relatively inexpensive noise reduction tweak.

marce's picture

I would say that it would be money well spent when compared to the price and functionality of some Audiophile based devices, and would provide true isolation, could you put a link up please, it may be the answer to my dreams:)

Phil_C's picture

T.H.E. Show Newport 2015
Digital Audio Advanced Lecture

When this screen opens, scroll down to find the Digital Audio Advanced lecture.

Go about 42 minutes into the lecture to hear about the Ethernet to Fiber Optic Bridge idea.

Michael Lavorgna's picture to run fiber from your router to a switch which would feed all Ethernet to your hi-fi. This would essentially isolate the switch from any electrical noise coming from the router. Some have raised the question of whether or not the fiber converter at the receiving end will itself introduce some noise since it is a powered device...

I've got my eye on the TP-Link (on Amazon) which run $44.79/ea. Add in the fiber cable and you're looking at roughly $100 depending on the length of the fiber run.

marce's picture

The SOTM has a isolation transformer (Hanrun HR602498) that is present on every Ethernet interface anyway and some through hole capacitors... Considering the noise we are concerned about is high frequency these PTH capacitors are as much use as a chocolate fireguard... The lead inductance alone will make them pretty useless, they should have at least attempted to do the job properly and use SMD devices with the minimum of stray inductance.
Sotm are correct in that there are magnetics available for 10GBase-T

Whether adding another set of magnetics in the middle of your Ethernet connection is going to do anything I have doubts with the Sotm device....
The other devices is for isolating EMC rooms and other instances when you want Ethernet in a shielded room, a different ball game to audio, but if you have the money and think the noise is a problem then these will do the trick, or just convert to a fibre LAN round your house, something I would love to do as our home network is growing larger every day.

marce's picture