Shielded Ethernet cable suggestions to cure ground loop like hum

stangman67

I feel for you! I went through the same thing with him after I put my VPI table in the loop and finally traced it down to a dimmer switch. Was definitely a rage inducing troubleshooting process.

Good luck with figuring it out!

heiney9

Actually mine looks more like this one in color and has the grounding wire

https://www.ebay.com/itm/185505028283?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=185505028283&targetid=1263104805766&device=c&mktype=&googleloc=9021890&poi=&campaignid=14859008593&mkgroupid=130497710760&rlsatarget=pla-1263104805766&abcId=9300678&merchantid=118887902&gclid=Cj0KCQiAofieBhDXARIsAHTTldp_-0UtcG4gKtX2kDhQYX1MAciqF55atp8TzMB-fTDLb_hKYbeFTXcaAsqaEALw_wcB

ALL212

So…

If that Ethernet surge plugged the words are remembered, no hum.

If you ground the green wire does it forget the words?

STP - absolutely cat 5e or better but STP. Regardless of this issue use STP if the budget allows. Mono price has cat 7 and 8 and if you don’t care about color you can sometimes get good prices.

Not all pairs in cat wiring are used for TCP/ip and it’s not impossible that the wire is fine but your end point devices aren’t quite wired under the full standards correctly.

heiney9

A2 - This is the current cable I'm using......I was under the impression it was STP?

https://www.amazon.com/gp/product/B00HEM5YJE/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

H9

ALL212

Yep - it states shielded and the connections appear to be metal.

So you have good cable. What also needs support for STP are the endpoints. The 8 wires don’t provide the shielded ground, the connectors/ connections do via the foil or mesh around the wires.

This isn’t a definitive step to be rid of the humm but it does mean you’ve got a good Ethernet wire.

There are other threads about using fiber and it’s not particularly expensive to try a basic setup. If this a ground loop issue a fiber drop should kill that.

Roughly:

Good short Ethernet cable to a converter. Converter outputs are fiber (fiber patch cable - probably about $1 / foot) other end fiber to converter and good short Ethernet to the device. STP not required.

$60 some odd + fiber patch cable and a couple of short Ethernet cables for troubleshooting. Then go nuts on parts if this works.



https://www.amazon.com/Gigabit-SFP-Dual-Transceiver-1000Base-Tx/dp/B099JF9KJD/ref=mp_s_a_1_1_sspa?crid=3HYEJ6O0QIB3S&keywords=fiber+to+ethernet+converter&qid=1675627266&sprefix=fiber+to+ethrr,aps,101&sr=8-1-spons&ufe=app_do:amzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyT1RZMVYzN09aS1IxJmVuY3J5cHRlZElkPUEwODU0MjQ5MkwzUjRDSjQ4WFlCMCZlbmNyeXB0ZWRBZElkPUEwNTg0NDIxMjBaODRQMUIwVk1YUCZ3aWRnZXROYW1lPXNwX3Bob25lX3NlYXJjaF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

SCompRacer

Like this. (Aaron introduced me to this last year. Thanks Aaron!). IIRC Ed the SRT king has them too. Eventually I'll mount them on screen behind rack. Most folks will use the wall wart on the 'dirty' side FMC and use a good linear PS for the 'clean' side FMC. There are single SFP and multi-mode (dual) SFP modules. These are dual or duplex LC to LC fiber. Just ensure you buy the correct fiber cable to match the SFP modules you go with. They were out of single SFP's when I purchased mine.



This PS was ~$90 on Amazon. Uses Vishay BC caps. While it has two 5v outputs, I don't connect both modules with PS or I lose galvanic isolation. Some suggest connecting dirty side FMC to different outlet.
https://www.amazon.com/dp/B07T44S4MV?psc=1&ref=ppx_yo2ov_dt_b_product_details



My stuff... ~ $167.
Two SFP's. Available as single or multi (dual). These are the ones Small Green Computer uses/suggests. Their kit is ~$350 with their PS.
https://www.amazon.com/dp/B003CFATYM?ref=ppx_yo2ov_dt_b_product_details&th=1
Short fiber (you have to observe a gradual bend radius so you don't damage fiber).
https://www.amazon.com/dp/B07YLCQLGK?psc=1&ref=ppx_yo2ov_dt_b_product_details
Two of these.
https://www.amazon.com/dp/B08Z7BZG5K?psc=1&ref=ppx_yo2ov_dt_b_product_details
The PS.
https://www.amazon.com/dp/B07T44S4MV?psc=1&ref=ppx_yo2ov_dt_b_product_details

I already had Cat STP patch cords. My wall jacks are shielded as well.

msg

Cool stuff, Rich! Might check out one of those power supplies to use with the SBT.

ALL212 wrote: »

Yep - it states shielded and the connections appear to be metal.

So you have good cable. What also needs support for STP are the endpoints. The 8 wires don’t provide the shielded ground, the connectors/ connections do via the foil or mesh around the wires.

This isn’t a definitive step to be rid of the hum but it does mean you’ve got a good Ethernet wire.

There are other threads about using fiber and it’s not particularly expensive to try a basic setup. If this a ground loop issue a fiber drop should kill that.

Roughly:
Good short Ethernet cable to a converter. Converter outputs are fiber (fiber patch cable - probably about $1 / foot) other end fiber to converter and good short Ethernet to the device. STP not required.

$60 some odd + fiber patch cable and a couple of short Ethernet cables for troubleshooting. Then go nuts on parts if this works.

Ern, question I had earlier in the thread was re: whether there were metal shields on the original ethernet cable. There was a lot of activity so it may have been missed.

If no shielded conns on the first cable, then the noise is transmitting across the signal pairs, yes.

If there were shielded connectors on that first cable as well, then it makes sense to try to either defeat the shield on the connector on the far side, or remove it altogether. Same thing Rich mentioned with the use of the Kapton tape on that USB connection, and also mentioned by @Groundrod speaking specifically to the ethernet connector shields.

Of course if not yet tested, the other easiest option would be to use a regular ethernet cable with no shielding if one on hand. I think it's unlikely that this noise is being picked up along the way. Seems more likely it's being transmitted from the source.

Also - I may have missed this - but, @heiney9, with the ethernet still in place and hum present on the speakers, did you ever disconnect your coax from your modem to see whether the hum dropped away?

There were a couple of key questions here that I'm not sure were answered, but I may have missed them.

That fiber conversion is a surefire fix, @ALL212 @SCompRacer, and looks to be nicely affordable, as well, not to mention, a pretty friggin' neat idea. Interesting upgrade. I like that power supply. I think I'm gonna try one of those for my SBT.

msg

Gardenstater wrote: »

I know this isn't the same situation, since it is a USB digital cable in this case, but before I got the SBT and I used to connect up to my ifi nano idsd DAC from my computer via USB cable, I used to get 8kHz packet noise spikes that was very annoying and because I was so attuned to hearing it, it destroyed my enjoyment of music (my guests barely heard it, except quiet between songs). It got worse the higher the amplification. Powering the DAC separately and not using the USB for the power did not cure the problem. The noise was coming through the digital wires of the USB because the computer digital output was contaminated with it, for whatever reason.

So digital wires can definitely carry or pickup an analog noise signal, despite the 1s and 0s thing seeming to proclude that. The quality of the source is a factor.

@SCompRacer Rich mentioned this earlier in the thread, but the USB noise situation is very similar to Brock's ethernet situation. I fought through that USB issue as well.

I learned that there are two ways USB audio can be hosed up:

1. If your DAC is running off the same USB bus as other USB devices, which is quite likely, you are passing audio on the same USB bus as other USB traffic. A spinning external hard drive polling and parking will present as noise in your audio. So will use of a mouse, and it's an extremely annoying sound.
2. You may also notice that keyboard and mouse control becomes erratic and unreliable while playing audio over USB.

The fix for me was to install a dedicated USB 2.0 card for connection to a USB DAC to remove the USB bus noise. I didn't have a compound issue with the power noise, but it happens. There are special cables you can buy that separate the signal and power paths to remove noise and purify the signal path. iFi makes one, and there's also some guy out there who was making something. Just checked my notes - the "USB Disruptor".

@SCompRacer - do you still have that fancy USB card?!?

msg

Disregard my posts above - you answered your question here with this post where you mention using the Tripp-Lite device:
https://forum.polkaudio.com/discussion/comment/2713233/#Comment_2713233

By using Tripp-lite inline device, presuming you used a regular ethernet cable in one of the ends of it, you removed the shielding on the cable connectors from the path, which is likely what's been transmitting the hum across the connection path.

SCompRacer

msg wrote: »

@SCompRacer - do you still have that fancy USB card?!?

Yes, I still have the discontinued Sonore Audiobyte USB to i2s interface in a Twisted Pear BIII 9038Pro DAC, TP Mercury I/V stage. The Audiobyte has USB isolation and topped out at Native DSD128. It also has a switchable on/off oversample filter for PCM, 384kHz. This is parked for now as I have a Gustard R26 DAC with Singxer SU-6 DDC. The R26 will do 768kHz/DSD512.

I also have an Amanero USB to i2s module with Twisted Pear Hermes USB isolator and TP Cronus reclocker.