DJM ACTIV Audio Ethernet EMI Filter Review (Bonus!)

[pablolie]

App level? I don't know of any app level error checking that operates over TCP/HTTP in a LAN. They rely on TCP for that.

There are UDP level applications that perform their own checking (e.g. NFS) but that is not what is used in home audio streaming.

Indeed true. UDP apps often craft their own tailored recovery methods if they need them. TCP doesn't need it, really, but there are extensions to it to further its reliability. Defense and some financial stuff. Proprietary secretive stuff. And as you said... irrelevant in home audio streaming.

Stuff exists that would be far more effective if a network path becomes compromised and the application is critical. Redundancy design... fast rerouting to a hot standby... alternate geography reliability zone fallback... none of that is truly applicable to our home audio hobby...

 

[Chrispy]

Indeed true. UDP apps often craft their own tailored recovery methods if they need them. TCP doesn't need it, really, but there are extensions to it to further its reliability. Defense and some financial stuff. Proprietary secretive stuff. And as you said... irrelevant in home audio streaming.

Very odd as I hit like for this post I got a window saying are you sure? That's new. Don't understand why particularly either. I just thought it an interesting angle beyond my pay grade....

 

[michaelahess]

This is a review and detailed measurements of the DJM ACTIV Audio Ethernet EMI filter. It was sent to me by the company and costs US $1,950.
View attachment 380788
If there was an attempt to justify the price of a small component like this, DJM has done it. The unit feels super dense and solid and a nice shiny finish and writing which doesn't come across in the picture well. There is an ethernet port and external power supply feed on the left of the indicator LEDs. The power supply is a proper, Meanwell supply. On the right is the outbound Ethernet port. Operation was automatic and without any impact despite me connecting and disconnecting cables a number of times.

This is a proper company building this device, unlike many high-end audio tweaks seeing specifications and certification not only in the company website, but also back of the device (abbreviated here):
View attachment 380789

Here is the filter specs:

View attachment 380790

I wish a transfer function graph was provided as I can't quite tell where the filtering starts from, other than full 100 dB at 10 kHz. Alas, I don't have equipment to measure noise and interference on Ethernet filter either so can't provide plot it that. But I did find an indirect way to do so at the end of this review.

DJM ACTIV Audio Ethernet Filter Measurements
As frequent readers of ASR know, my main focus is to see if the output of an audio device changes as opposed to what goes in it. That is what we hear and what ultimately matters. To that end, I pulled out the yet to be reviewed Eversolo DMP-A8 streamer for this testing (full review to come shortly) for the measurements here. Naturally Ethernet connection was used to stream test signal to the A8 and balanced analog outputs measured. Here is the dashboard of DMP-A8 with volume reduced one notch and Ethernet connection without the EMI filter:
View attachment 380791
Superb performance as we expect from Eversolo. However, there are some noise and distortion spikes (well under audible threshold < -130 dB). Can some of this be from Ethernet link? Let's insert the AVTIV Audio filter in the path:
View attachment 380792
There is difference other than run to run variations. Note that this doesn't mean noise was not filtered. But that the A8 is implemented well as to be isolated from Ethernet. What is there as far as spurious noise components is inherent in the DMP-A8, not from incoming noise on Ethernet.

To see if any ultrasonic noise is filtered, I ran 1 MHz FFT with and without EMI filter:

View attachment 380794
Again, we see noise components but they must be internal as there is no difference with and without filter. I also tested with J-test signal with similar outcome:
View attachment 380795

I then decided to just look at the spectrum of noise without streaming anything to DMP-A8:
View attachment 380796

Again, no difference.

For the final test, I decided to use my AC transformer that powers my headphone measurement gear. This has proven effective in other interference tests and did the job here:
View attachment 380797

We see that there is no difference at mains 60 Hz interference but as we go higher in frequency, we progressively see more attenuation. Keep in mind though that the the graph is massively magnified with the top of the graph at whopping -130 dB or 15 dB below threshold of hearing. So this noise would not be audible in either case. But we do see that filtering does exist.

Conclusions
I commend DJM Electronics for not only offering to send this filter, but insisting that I test it despite me cautioning them that I have not found any of these devices to make a difference that would be audible. Note that their company's core business is EMI filtering and is not focused on audio per se. On that front, this seems like a performant device. I think it would have good application in industrial domain. I have for example heard of CNC machines causing interference over Ethernet.

For audio, my tests on high performance streamers shows that the product is not needed. However if you are experience data errors on Ethernet due to special situation you might have, the DJM Electronic's ACTIV Audio Ethernet EMI filter may help deal with that.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-au

 

[pablolie]

Very odd as I hit like for this post I got a window saying are you sure? That's new. Don't understand why particularly either. I just thought it an interesting angle beyond my pay grade....

You can be sure. If you don't trust accuracy you could go as far as implementing a block chain protocol, which forces several agreed upon entities to agree and validate data.

Seems a bit of an overkill for audio to circle between the holder of the original recording, your streaming source and your end device to establish that.... but if anyone is willing to pay handsomely for such ultimate assurance, hey, it can be done.

 

[michaelahess]

I've been a network engineer for nearly 30 years. There is no environment I haven't dealt with (including military systems training) that would benefit from this.

Completely useless device.

If you put Ethernet anywhere that would impact performance, you aren't doing your job right.

 

[pablolie]

I've been a network engineer for nearly 30 years. There is no environment I haven't dealt with (including military systems training) that would benefit from this.

Completely useless device.

If you put Ethernet anywhere that would impact performance, you aren't doing your job right.

thank you. at the current 800GE standard I would think Ethernet is pretty capable for audio apps, provided you want to spend on the best possible. about 50k a single interface with basic functions right now, special promo.

 

[Chrispy]

You can be sure. If you don't trust accuracy you could go as far as implementing a block chain protocol, which forces several agreed upon entities to agree and validate data.

Seems a bit of an overkill for audio to circle between the holder of the original recording, your streaming source and your end device to establish that.... but if anyone is willing to pay handsomely for such ultimate assurance, hey, it can be done.

It was this forum's software interjecting that....

ps or at least it sure looked like it

 

[pablolie]

It was this forum's software interjecting that....

I love this forum. Because it has not once ever injected unfounded bias into any discussion ever or moderated in bias against halfway educated dissenting opinions.

So I wonder why you encountered that - I have never seen it.

None of my points represent an attack on the review of a product. I have often said that the measurements here are the reason I joined and stayed on... because they allow me to establish all I need to know to make up my own mind.

 

[Chrispy]

I love this forum. Because it has not once ever injected unfounded bias into any discussion ever or moderated in bias against halfway educated dissenting opinions.

So I wonder why you encountered that - I have never seen it.

Me either. It was weird. If it was externally influenced makes me wonder even more. It reminded me of sometimes when clicking on a youtube video a window comes up asking if you're sure to play or other options to get out....

 

[phoenixdogfan]

There may be high RFI environments where this kind of specialized filtering proves useful:

But a typical audio listening room is probably not one of them.

 

[pablolie]

There may be high RFI environments where this kind of specialized filtering proves useful:

View attachment 380817

But a typical audio listening room is probably not one of them.

nor is a typical hospital or fast trading room or SpaceX or missile reponse and such. Isn't it odd they'd rather invest in top networking gear and fully redundant architectures rather than EMI filters?

 

[-dsr-]

For much less money, we can run ethernet over fiber optic and be completely immune to any interference that this could possibly filter out.

A 100 foot preterminated optic cable is around $40; if your equipment already supports SFP or SFP+, add $20 to each end for the transceiver and you're done. If it doesn't, a copper-to-fiber media converter is an additional $15-$25 per side for up to 1Gb/s, and under $100 for 10Gb/s. So at worst, you get much much better performance and a 100 foot reach for under $300. At best, $80.

 

[Cal_Cobra]

I've been in enterprise/commercial networking for decades, this device is utter snake oil. If there's errors, it's almost always an equipment issue, faulty cable, faulty SFP, etc (or a config issue, although less likely these days). As far as "industrial" equipment goes, most companies with a need would be using ruggedized switches and firewalls/routers, but for EMI resilient gear, you're getting into the niche. I worked at a company [that shall remain unnamed] that may or may not have made specialized networking gear for military applications made to withstand EMI pulses during a nuclear war. That said, we're talking about an entirely different application.

 

[pablolie]

For much less money, we can run ethernet over fiber optic and be completely immune to any interference that this could possibly filter out.

A 100 foot preterminated optic cable is around $40; if your equipment already supports SFP or SFP+, add $20 to each end for the transceiver and you're done. If it doesn't, a copper-to-fiber media converter is an additional $15-$25 per side for up to 1Gb/s, and under $100 for 10Gb/s. So at worst, you get much much better performance and a 100 foot reach for under $300. At best, $80.

Agreed, but also within the designated distances for standardized IEEE compliance there is zero difference between any cable standard though.

Their standards are very demanding.

 

[Highvolt60]

Does this mean there is an Eversolo DMP-A8 review coming soon ?

 

[TheWalkman]

PT Barnum, would, no doubt offer these as buy five, get one free. (And a lifetime pass to the circus, no extra charge.)

 

[Fafnar]

Devices like this really mess with the rating system. It is very expensive but does what it says. However what it does is also irrelevant to home audio and I imagine pro audio has better ways to deal with anything where this might be applicable.

So I want to rate it both: useless and fine.

 

[Hayabusa]

I wish a transfer function graph was provided as I can't quite tell where the filtering starts from, other than full 100 dB at 10 kHz. Alas, I don't have equipment to measure noise and interference on Ethernet filter either so can't provide plot it that. But I did find an indirect way to do so at the end of this review.

You could have measured the transfer function from one side to the other side on one specific wire pair while not connected to LAN?
Not up to 40GHz of cause but up to how high the AP can go,

 

[amirm]

You could have measured the transfer function from one side to the other side on one specific wire pair while not connected to LAN?

I don't think it would operate without a valid signal at the source at least.

 

[Sokel]

Company operates since 1978 and it's indeed about mil stuff.
It also offers EMI filters,shields,etc for USB,HDMI,etc. and they seem highly specialized about it.

There's not a word in their site about audio,I guess there were curious about the proprietary (as they point out) technology's performance and wanted to cross-check it with Amir?
Although I guess some sales wouldn't hurt.
At least it works and does as it says.

Thanks Amir!