Ethernet versus USB, measurements and listening tests

0 Members and 1 Guest are viewing this topic. Read 830 times.

audioengr

Empirical Audio has designed what we believe to be the best performing USB and Ethernet interfaces.  Both are available as DAC inputs as well as external converter devices.  The Interchange is our external Ethernet device and the Off-Ramp 6 is our external USB device.  The XMOS USB interface is galvanically isolated and by virtue of the Ethernet PHY, the Ethernet is also galvanically isolated.  Both interfaces are based on the same design, with the same clocking from our "Turboclock".  Both use the same power supply, the Dynamo.  The Master Clocks in the Off-Ramp 6 are both galvanically isolated from the USB cable.  The power in the USB cable is provided by another device of ours, the Power Block, so power from the computer in the USB cable is not utilized.  The Interchange is available as a product, but the Off-Ramp 6 is not available yet.

We set up the measurement  testbed so that both devices would be located in the same place and use the same power outlets and the same digital output (S/PDIF coax) and power cables.  The input USB cable was a 16-foot off-the-shelf inexpensive cable and the Ethernet cable was about 40 feet of CAT5e and CAT6, some in the wall and some as a CAT6 pluggable cable.  The 16-foot USB cable was run from a Mac Mini that is optimized for audio playback.  The Mini has both Amarra and Jriver for playback software.  Both will be used for listening tests.

Jitter measurements are made using a 7GHz Tek scope with advanced Jitter Measurement software app on it.  All units were given 30 minutes to warm-up and stabilize.

Measurements:

USB jitter distribution:



Ethernet jitter distribution:




The jitter distribution from USB is a bit wider, but still in the noise.  We are talking 23psec of jitter versus 18psec of jitter from the Ethernet interface.

USB jitter spectrum:



Ethernet jitter spectrum:



Again, these are both similar.  Below 600kHz, the jitter is essentially non-existant.

Listening tests:

For USB, listening tests were .wav files played from both Amarra and Jriver from the Mac Mini.  Memory playback mode selected for both.

For Ethernet, listening tests used the same files played from Jriver from the Mac Mini.

Tracks included 44.1 tracks of:

1) The Doors "Riders on the Storm" - listening for the rain, thunder and vocals
2) Pat Metheney "Half Life of Absolution" - percussion, electric guitar
3) Michael Hedges "Rickovers Dream" - acoustic guitar
4) Andreas Vollenweider "Behind the Gardens/Behind the Wall/Under the Tree" - paddling canoe in a swimming pool and harp

Ethernet impressions:

Very clear, but not dry.  Highest frequencies remain coherent and attached with high degree of focus to their sources, be it rain, percussion or water being paddled.  Acoustic guitar sounds are very live and pinpoint focused.  Liveness is almost startling at times.

USB impressions:

Very bold, vivid and almost glowing. Virtually identical results from Amarra and Jriver.   Highest frequencies are a bit confused, causing the guitar to be a bit unfocused or at least the highest frequencies are not firmly attached to the same lower frequency sounds.  Almost like an overly echoic chamber.  Still very pretty sounding though and nothing is being missed.  You still hear every detail.  The highest frequencies are only a bit misplaced in the sound-field.  If your system was not set-up to deliver a pin-point image, you might not hear this difference.  It is subtle, but audible enough so that you know this is a recording and not the real McCoy.

These differences are small and require critical listening with optimum tracks to hear the differences.  With certain instruments however, it's the difference between a "live in the room with you" sound and a "pretty" sound from a recording.

So, if the jitter measurements do not show a significant difference, what is going on?  Could it be that I need a really expensive USB cable to get these high-frequencies to be coherent?  This is the only hardware variable that I can think of.  Other than this, I have to deduce that somehow USB is "tainting" the data somehow.

Even if a $2K USB cable would fix this, why would I waste my money on that?  I spent maybe $25 on CAT7 cables and $130 for an isolator for Ethernet.

I have an extensive list of reasons why I prefer Ethernet to USB, but this is the one that counts, sound quality, liveness.  The second reason is that there are less hoops to jump through and less additional expenses to achieving that accurate, live sound.

Steve N.
« Last Edit: 24 Jan 2018, 05:56 pm by audioengr »

KLH007

  • Full Member
  • Posts: 335
Re: Ethernet versus USB, measurements and listening tests
« Reply #1 on: 24 Jan 2018, 03:50 am »
Steve, What was the output from the 2 units under test?

audioengr

Re: Ethernet versus USB, measurements and listening tests
« Reply #2 on: 24 Jan 2018, 04:43 am »
Steve, What was the output from the 2 units under test?

S/PDIF coax to a 75 ohm termination inside my scope.

Steve N.

mresseguie

Re: Ethernet versus USB, measurements and listening tests
« Reply #3 on: 24 Jan 2018, 09:59 am »
Steve,

Thank you for posting this. It's useful information IMHO.

Michael

mav52

Re: Ethernet versus USB, measurements and listening tests
« Reply #4 on: 24 Jan 2018, 04:54 pm »
Steve maybe its not the same device, but back around Jun 2017 you noted " Unfortunately, the Ethernet renderer has one issue right now:  it must be powered first and then the Ethernet cable plugged in.",  is this the same device and if so has that issue been resolved. http://www.audiocircle.com/index.php?topic=141373.0

Also, will you be putting this new item on your website ?

audioengr

Re: Ethernet versus USB, measurements and listening tests
« Reply #5 on: 24 Jan 2018, 05:52 pm »
Steve maybe its not the same device, but back around Jun 2017 you noted " Unfortunately, the Ethernet renderer has one issue right now:  it must be powered first and then the Ethernet cable plugged in.",  is this the same device and if so has that issue been resolved. http://www.audiocircle.com/index.php?topic=141373.0

Also, will you be putting this new item on your website ?

It turned out that this sequencing problem was due to Jriver.  Now, in order to get the best SQ, one must open Jriver first and then power-up the Ethernet interface, whether it's the DAC or the Interchange.  The difference in SQ is not huge, but audible.

I hope to put the Interchange on my website in the next month or two.  It looks identical to the Off-Ramp, except for silver boxes and front panels and a matching Dynamo is included.  It can be used right now with Jriver or Audirvana+.

Steve N.

reverendo

  • Jr. Member
  • Posts: 3
Re: Ethernet versus USB, measurements and listening tests
« Reply #6 on: 24 Jan 2018, 11:24 pm »
Steve, my DAC, a Resolution Audio Cantata, has an ethernet input. Do you know how it is similar and/or different from the way you implement it? Last time I gave it a try was a couple of years ago and the sound was great, but the upnp was not very user friendly at the time, so I stayed with USB.
What is the best scenario for using ethernet in your case? What do you use in your chain? Any optic conversion for galvanic isolation?
Hope hearing from you
Best
André

audioengr

Re: Ethernet versus USB, measurements and listening tests
« Reply #7 on: 25 Jan 2018, 12:20 am »
Steve, my DAC, a Resolution Audio Cantata, has an ethernet input. Do you know how it is similar and/or different from the way you implement it? Last time I gave it a try was a couple of years ago and the sound was great, but the upnp was not very user friendly at the time, so I stayed with USB.
What is the best scenario for using ethernet in your case? What do you use in your chain? Any optic conversion for galvanic isolation?
Hope hearing from you
Best
André

Andre - My Ethernet is DLNA compatible.  I'm not sure what your uPnP supports.  Probably DLNA.  If it is recognized and plays with Jriver and Audirvana+, its DLNA.  Like USB interfaces, there is a wide range of performance of Ethernet interfaces.

I do Ethernet 2 ways: wired from the router and wireless using my WIFI solution.

For wired, I power my router from a fast LPS that has earth ground connected to DC common in the DC power cable.  I use a short CAT7 cable from the router to an EMO EN-70e isolator and then a longer 6 foot CAT7 cable to the DAC input.

For WIFI, I power a WIFI adapter (WPS) from a similar fast responding LPS that has earth ground connected to DC common.  Same short CAT7 cable from the WIFI adapter to the isolator and then longer CAT7 to the DAC.

Unfortunately, I cannot sell just power supplies, but I can recommend the Sboosters.  You will need to jury-rig the earth-ground to DC-common wire.

Steve N.
Empirical Audio

reverendo

  • Jr. Member
  • Posts: 3
Re: Ethernet versus USB, measurements and listening tests
« Reply #8 on: 25 Jan 2018, 12:37 am »
Thank you for a swift response, Steve. Yes, it works with DLNA.
At the time I played with Fiber Conversion using this converter (https://smile.amazon.com/gp/product/B0034CSUD0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1) and these patch cables (https://smile.amazon.com/gp/product/B008BQ1LOE/ref=oh_aui_search_detailpage?ie=UTF8&psc=1). I didn't use an LPS with the second convertor, where it would be critical, but the results were still very encouraging. Do you think that the EMO EN-70e would do a better job, and, if so, why?
I used CAT6 cables. Any opinions why the CAT7 would be a better option?
Last, but not least, what does "You will need to jury-rig the earth-ground to DC-common wire." mean?
Thanks again
André

audioengr

Re: Ethernet versus USB, measurements and listening tests
« Reply #9 on: 25 Jan 2018, 02:59 am »
Thank you for a swift response, Steve. Yes, it works with DLNA.
At the time I played with Fiber Conversion using this converter (https://smile.amazon.com/gp/product/B0034CSUD0/ref=oh_aui_search_detailpage?ie=UTF8&psc=1) and these patch cables (https://smile.amazon.com/gp/product/B008BQ1LOE/ref=oh_aui_search_detailpage?ie=UTF8&psc=1). I didn't use an LPS with the second convertor, where it would be critical, but the results were still very encouraging. Do you think that the EMO EN-70e would do a better job, and, if so, why?

No, earth-grounding the negative lead on the DC cable is better.  The isolator helps a little.

Quote
I used CAT6 cables. Any opinions why the CAT7 would be a better option?

Higher bandwidth and better shielding.  Even CAT6S is better.

Quote
Last, but not least, what does "You will need to jury-rig the earth-ground to DC-common wire." mean?

It means: if the supply has no ground in the AC cord, then you will need to run a separate wire to the outlet and connect to earth ground, either by screw or banana plug in the outlet.  The other end of the wire connects to the negative of the DC cable by soldering etc..

Steve N.
Empirical Audio