An interesting "Linus" video on the "Audio Quality Ethernet"

Audio Gear Talk
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OK, I’ve done the first part.

Made a -120dBFS 24bit/48kHz pink noise track in REW, converted it to FLAC, loaded it into my local library and played it in Roon.

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Volume on HPA4 was at 0dB, i.e. maximum. This equates to playing both AHB2s at full volume. 380W per channel into 8 ohms.

Couldn’t hear a thing from the speakers with my ear pressed up against the drivers. No noise, no hiss, nothing, SILENCE.

Network and RPi aren’t contributing anything AUDIBLE to the noise floor of my setup, despite using an enterprise switch with its own built-in SMPS, standard Cat6 cables AND powering the RPi via PoE+. THE PoE+ HAT has its own SMPS too which offers up 3.3 V, 5 V and 12 V from the nominal ~48 V supplied from the switch.

There’s a lot of noise around here, but none of it coming from ethernet… :rofl:

EDIT:
Streaming audio is just data. It’s just bits - you can’t change the “sound” of streamed audio data, because that would change the data and the TCP checksum would fail, there would be packet retransmission, potentially packet loss and gaps in playback. Jitter is a non-issue for TCP. Data is time independent and buffered and reconstructed at each interface.

So the audiophile ethernet aficionados tell us it’s not the data, it’s “NOISE” propagating via ethernet cables and polluting the analogue output of the DAC. My experiment says otherwise - there’s no audible noise propagating into the DAC from either the ethernet, or the PoE+ powered RPi because there’s nothing coming out of the DAC. And it has to be the least audiophile network setup going.

Standard Cat6 cables and patch panels, a standard enterprise grade switch, even PoE+ power to the (ca. £200) RPi end point (this also opens up questions around high-end streamers!). No fancy USB cable connecting the DAC. Interconnects between DAC/HPA4/AHB2s are as per Benchmark’s spec - Canare Starquad cable (2 of them are Van Damme Starquad cable, which makes no difference) and Neutrik XLRs, ordinary SPOFC speaker cables connected via Neutrik Speakons.

The Benchmark gear has sufficiently low THD+N to resolve Hi-Res audio, i.e. to get out of the way and let anything else be heard. In this possibly worst-case scenario, it turns out there is nothing else to be heard when it’s playing “silence” (-120dBFS test track) amplified to the maximum capability of the gear. Were I playing a 0dBFS signal at this level, my speakers would go up in smoke and the AHB2s would shut down. I’d also suffer permanent hearing damage.

EDIT 2: OK, this is a little nuts, the HPA 4 has a further 15dB of gain to offer. It can output up to 20 Vrms on the balanced analogue outputs. At about a further 4dB of gain, I could hear a faint hiss which stopped if I paused the noise track. Hmm, was I actually hearing a -120dBFS pink noise track? Only one way to find out - I made a -120dBFS 1 kHz square wave and listened to that. Sure enough, at about +4dB, I can make out a 1kHz tone. Yes, there’s a little hiss with it, but the tone is there. So I have to push a -120dBFS test track into audibility before I can make out any noise coming from any of the equipment. So even listening to music with 100dB transients, the noise is at least 20dB below the threshold of audibility. And I suspect here, I’m hitting the limits of the Benchmark DAC, line amp and power amps.

Nothing from ethernet, or from the RPi is adding anything audible.

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69

We can make it happen :stuck_out_tongue_winking_eye:

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One of the most memorable movies of my youth!

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If bjc is blue jeans cable, you haven’t heard a good cable yet. I did a test a couple years ago based on recommendations from another audiophile site which claimed bjc were much better than cables many times their price. So I bought a new pair of their top of the line IC’s and compared them to my current IC’s that cost more than 8x more than what the bjc cost.
After hundreds of hours of break in, I sold the bjc. They were dull and lifeless compared to my current cables.
Try a top quality cable to see if you hear the difference.
Also, Ethernet cables do make a sizable sq difference

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Agree with all your assessments. Power supplies can make a difference but replacing a good switching power supply with a mediocre linear PS, not necessarily for the better. Digital and power conductors–snake oil. Analogue conductors (speaker cables and interconnects)–could, under some circumstances, make a tiny difference, but nothing like what the vendors and users of $1500 speaker cables wax about.

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I tried a $3000 audiophile cable on my kettle. I can’t do without it now, the water tastes so much better. Even the lass commented who knows nothing about me changing the lead how she thought it boiled quicker.

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To my knowledge, the guy who offered a $1,000 wager on a DBT was never obliged to pay out.

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I’m afraid I disagree. An ethernet cable’s role is to get the bits from A to B. If it’s doing anything else, then something is amiss.

Audiophile ethernet cables are often claimed to be made to Cat7 or Cat8 standards, which are shielded. Shielding defeats Ethernet’s inherent galvanic isolation and can introduce artifacts into the audio chain.

If I’m honest, most of the constructions I’ve seen wouldn’t test out to Cat6 requirements, let alone Cat7 or Cat8.

They’d make no difference in my system as everything is Cat6. No continuity of shielding across the patch panels or faceplates.

BJC is one of the few manufacturers who test their cables to ensure they meet the network specification standards. That’s why they cost more than vanilla ethernet cables. Testing takes time and the equipment needed costs serious money.

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Tasty comment, though I’d have to agree with our resident scientist and his view on that issue.
:popcorn:

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While I agree that nearly all reviews are unreliable, there is another possible explanation that would explain why only good reviews are published: They elect not to publish bad reviews. A reason would be not to cause bad blood with a possible advertiser or supplier of goods, possibly there are contracts as well.

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Yeah, that’s a good point. Six of one; half a dozen of the other. :slightly_smiling_face:

It doesn’t change the fact that reviewers are an untrustworthy lot.

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No, it doesn’t change the fact that the whole ecosystem of manufacturers and reviewers is generally in a sorry state. Nothing new and in large part may be inevitable due to various factors.

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I need to find the post on ASR - I’m sure there’s a guy offering $10k on a DBT on DACs.

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Four or five years ago, there was someone on this forum who offered plane fare to a testing site and $10k to anyone who could reliably blind test, I think it was, cables.

No one every replied to him, as I recall.

OTOH, I’m not sure he would have ever carried thru with the offer.

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Solid work, Graeme, thank you.

It is a rare thing for such a well thought out test to be conducted and for findings to be shared.

The results are quiet enough to drown out the loudest contrarian claims. :blush:

An analogy I proferred elsewhere when discussing Ethernet and audio and trying to show what really happens:

** fireworks ignite and burn in the night sky **
Crowd: “ooooh! MAGIC!”
Bystander: “Certainly looks that way, but it boils down to chemistry. Copper-based compounds give off the blue light, brightness and whites are enhanced by Magnesium compounds, Strontium and Barium make it red. Various oxidisers are used to enable the reactions to occur!”
** blank stare **
Crowd: “MAAAAGIC!”

People would be less dogmatic and more open if the networking product claims in much of the marketing bumpf of kit claiming audiophile performance had a shred of engineering plausibility.

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Thanks Tel for your kind comments.

I love your analogy.

I have to confess, the “silent” test track wasn’t my original idea - I’m sure I read a thread here recently about using one to make sure a DAC wouldn’t mute it’s outputs with no input. If I find it again, I’ll credit the original poster.

It was a fun and relatively easy experiment to conduct, made all the easier by the capability of Benchmark Media’s SoTA noise performance.

Until today, I would never have believed you could push a -120dBFS track into audibility. It turns out you can, and not only that, it’s even possible to pick out a 1kHz test tone.

I’ll have to repeat it with my digital 'scope across the amp’s outputs. I’m curious to see what the 1kHz square wave actually looks like coming out of the amp. It won’t be pretty though, I’m sure…

There’s so much hot air around hi-fi and audiophilia that has been debunked by science, yet despite all of the evidence, there are still those who believe in MAGIC!

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It’s plausible (well, you proved it). With enough windings and enough juice, you could amplify amoeba flatulence into audibility.

This is an experiment that I’d be really interested in, the results would quantify what any extraneous noise looked like in relation to the signal.

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Nicely worded. Also nice cable managment. :slightly_smiling_face:

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Ah. The “barber theory” springs to mind here:

In a town with two barbers, you have to decide which one you will go to in order to have your mop trimmed. One is immaculately groomed with perfect hair, the other looks like he had an altercation with a cactus in a mattress-stuffing factory. Although it is counter-intuitive at first glance, you eschew the smart and well turned-out barber and go to get your hair cut by the guy who looks better suited to professional dumpster-diving than cutting hair.

This is the reason I am not showing my network. Not the stateful firewall, the routers, any switches and not the cabling. Nope. :rofl:

In all seriousness, Graeme, that looks pretty damn good. There are some parts of my OCD I can ignore (cable management in my own home is one of them - barring prudent separation measures for function rather than form); it seems you are a completist :slightly_smiling_face:

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