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Comment by Night_Thastus | Hacker News Reader

I know this sounds stupid, but I actually had something like this happen to me. It was due to the cable.

My PC is very electrically noisy on account of the GPU. This noise was coming out of all the ports, including the Ethernet port. It was making it through that port, by CAT-6 cable, to my switch. The switch then sent it to my Raspberry Pi I was using as a streamer, then into my DAC, amplifier and finally speakers. You could hear it, it was loud when a game started up.

The solution - swap out the CAT-6 with CAT-5 cable which doesn't connect the ground planes. Instantly solved.

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I think electrical engineers having done some RF designs generally regard audiophiles as flat-earthers explaining what is wrong with a flat map; they might get it right now and then, but always for the wrong reasons. Remember how in the 90ties you could hear an SMS coming to a phone near an audio device? Right! No physical connection and sure you can’t hear the 900mhz ish gsm signal, but the rectified and smoothed signal had an audible time division multiplexing (envelope). And the carrier wave often resonated with paths in the signaling path of the audio device.

The keywords are: EMI (electromagnetic interference), signal integrity, power integrity.

Memcpy can have second order effects due to EMI radiated by CPU, motherboard or coupled via power fluctuations.

There are audible and measurable effects of audio system clock jitter which in turn depends on oscillator power quality.

Someone mentioned that ethernet has isolation transformers. But isolation transformers have parasitic common mode coupling which can inject the noise to ground plane if interference is strong and device is susceptible enough

Watch the EEVBLOG on company which designed scope capable of measuring 1kV common mode signals. (present in EV electronics) https://youtu.be/I7ppDNLlEL4

Audiophile stuff is a weird mix of real effects and snake oil.

Yeah.... but somehow changing the memcpy method improved the audio also of the commenters. Unless the commenters have all the same PC, it all smell like "bias".

This, so much this. Many people ignore most of the things affecting sound quality in their setup. Audiophiles don’t, and they often go the extra mile to satisfy their compulsion for better sound—up to and including psychoacoustics.

If a $10,000 power cable makes your amp sound better to you, who’s to say it doesn’t?

the aunt of a friend promised sick people to talk to angels about their issues for only a modest sum. i'm sure those people felt at least a bit better afterwards, because they were of options otherwise.

on the other hand, they spent hundreds of dollars for nothing and if they eventually recovered they'd tell other sufferers about it, dragging them down too.

does the victims glimmer of hope justify her scam?

background: she herself suffered from an "incurable" illness for months, where she paid other angel conjurers (that's where she got the idea from). turns out it was just iron deficiency and easily cured with iron supplements. at that point she'd already paid several hundred dollars to those charlatans.

That is called ”caveat emptor” and it is the founding principle of America.

Just because the placebo effect is real, it's bad to advocate people spending $10k on a placebo.

Hey, some people buy ads on social media.

What do you mean the 90s? I can still hear my phone pining the tower when it's too close to my speakers ? (Eris E5 on balanced XLR into a Scarlett 2i4)

The common term is 'GSM buzz', you'll find a lot about it online.

I've also heard it in the 2000s.

On a Sunday morning I used to lie in with the radio on, sleeping on and off.

There was one song around 1999 that included the sound and also had my ring tone.

It was a very confusing time.

Found it: https://youtu.be/y8ClVMzt9Dw

[edit: added link]

I heard it just a couple years ago, when I used a 2G phone. 3G and 4G don’t have that fault.

Fault or feature? Was nice to get some warning your phone was about to ring

... in the 90s? It still happens today with my phone

No, we don't. And with having enough budget and skills we try our best to shield stuff we make. As for radio noises: just remember that every freakin physical body is an antenna. Not just wires. All we can do generally is tune things in such ways that they resonte in a range we need and be as silent as possible in all other frequencies.

Hum,Im pretty sure you mean STP vs UTP, and not cat5 vs cat6. Electrically, cat5 and cat6 are equal; cat6 is slightly thicker, has a thread separator in the middle, and its rated for higher frequency. Electrically? The same. STP cable (regardless if specced for cat5 or cat6) does have a ground plane.

Oh! That must have been it, thank you. I'm not very familiar, I just knew the cables were cat6 and cat5. Thought it might have something to do with the shielding.

Looking over the product page, it's marked as S/FTP

Yeah don’t use grounded cables if you don’t have ground to actually ground them.

At least that’s what I was told once upon a time since EE is definitely not my forte.

Correct. More specifically, if a shield is not actually grounded, all it becomes is a re-radiating antenna for all of the EMI around it, as well as a means by which to directly transfer electrical noise from one device to another.

I never see either of these terms on sites like Newegg. How do I know which is which? Which one am I supposed to use at home?

The "U" stands for Unshielded, the "S" stands for Shielded. For home use and office use, UTP is fine. STP makes sense in "noisy" (electrical or magnetic) environments, such as factory floors with heavy machinery, clinics & hospitals with specific machinery, etc. See more details on the kind of protection the shielding offers here: https://en.wikipedia.org/wiki/Shielded_cable

Makes sense, but my point was that I've never even seen an option to buy one kind of ethernet cable or other. Is it safe to assume the $15 StarTech cables I buy from Newegg are unshielded? And does the "TP" stand for "Twisted Pair"?

Yes and yes

I have a computer that will sometimes crash hard, frozen screen and mouse, awful static on the speakers and, interestingly, something coming over the ethernet port too. This interference goes up to the next device on the line, my network switch, and brings that to its knees too. Nothing can move through the switch while that computer is having a seizure. I can disconnect the wire at the switch and the network comes back to life within a minute.

I'm considering putting a sacrificial switch from my junk box inline to that one computer so maybe the rest of the network can survive its crashes.

That is probably the nic in said machine still being alive and unable to pass any received frames up to the os. When its buffer runs full, it starts spamming pause frames, which dumber switches just blast out every port effectively paralyzing the whole network segment.

You could verify this by running Wireshark on another machine, or try disable sending pause frames on the machine before it crashes via eg ethtool

Mmmmh interesting.

In my case just a few weeks ago I had an AP that went bananas, and was directly connected via ethernet to a RPi4, and made the Raspbian kernel panic on the Broadcom driver, randomly. Not long after the AP stopped working completely.

I cannot upvote you enough, as I've been through similar problems many times. But in your case you could just re-crimp one side of your cable with unshielded connector. This is actually a good practice not only for noise and ground-loop preventions, but electrical safety too. Also, CAT.6 doesn't require shielding like FTP/SFTP/etc. - I'm using a CAT.6 UTP right now.

And anti-audiophiles are sometime becoming even worse than manical audiophiles - because of their deep blind belief in their educated superiority (while in reality it's a bit .. untrue).

There's usually a grain of truth in that audiophile nonsense, that it could in theory have some material basis in reality. The problem is the complete rejection of the scientific method.

Or better, use devices designed with a propper grounding scheme and avoid the Raspi DAC for anything critical.

The raspberri pi isn't a dac, it's a streamer. It acts as a middleman to avoid using my PC as the source of the audio.

I'd definitely prefer a DAC with good filtering on its inputs so I wouldn't need to use a middleman, but that is expensive. One with a proper USB module with complete isolation can run ~$5000.

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