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The last meter - Common mode noise


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Winding the cable through tight turns will effectively cause it to be out of spec after breaching its minimum bend radius.

 

It will absolutely increase the likelihood of crosstalk where the tight turns have been forced and shift the pair alignments/twist rates. It will stop the inherent noise-rejection design of twisted pair from working properly. The very thing you want to avoid.

 

Still, if you think it has merit, fill your boots.

 

 

 

 

 

 

 

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Winding the cable through tight turns will effectively cause it to be out of spec after breaching its minimum bend radius.

-- No, just need a flexible cable and it has to be U/UTP

 

It will absolutely increase the likelihood of crosstalk where the tight turns have been forced and shift the pair alignments/twist rates.

-- No measurement have shown problems in that direction

 

How to do it?

 

https://www.fair-rite.com/wp-content/uploads/2022/04/OTA-Mar-Apr-PB-Toroid-with-credit.pdf

 

Torben

Edited by TRHH
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I couldn't see mention in the cited materials where the crosstalk issue has been dealt with or how the laws of physics with bend radii have been deflty sidestepped. Anyway, enjoy if it works for you.

 

It's refreshing to understand where 30 odd years of networking knowledge is wrong. Well, it would be if I could find something in the material quoted.

 

Again, enjoy your experiments.

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It's refreshing to understand where 30 odd years of networking knowledge is wrong. Well, it would be if I could find something in the material quoted.

- That 30 years old networking knowledge is not wrong! But in audio common mode noise can be an issue (please note I am NOT talking about jitter)

 

Based on a cost of 50-60 EURO it is a cheap solution.

 

Torben

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  • 1 month later...
On 20/02/2024 at 3:07 AM, TRHH said:

 

- That 30 years old networking knowledge is not wrong! But in audio common mode noise can be an issue (please note I am NOT talking about jitter)

 

Based on a cost of 50-60 EURO it is a cheap solution.

 

Torben

 

But that's not audio, it's networking.

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  • 3 weeks later...
On 20/02/2024 at 1:42 AM, TRHH said:

 

Based on a very interesting post:

"The choke cable – minimizing common mode interference over the last meter"

I have bullied this setup:

 

CommonModeNoiseFilter19022024A.thumb.jpg.af77a2952d1be2b8ea91cfc4e23f67e4.jpg

 

 

 

 

 

I can highly recommend such a setup on "The Last Mile" -  measurement and test have shown SQ improvement.

 

Torben

 

This is totally ridiculous. 

How are you maintaining category spec? 

 

This is why appropriate measurements matter!

The sad challenge is the OCD inclined reading this thread, will try making this cable. ;) 

 

Edited by Grizaudio
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On 20/02/2024 at 6:07 AM, TRHH said:

It's refreshing to understand where 30 odd years of networking knowledge is wrong. Well, it would be if I could find something in the material quoted.

- That 30 years old networking knowledge is not wrong! But in audio common mode noise can be an issue (please note I am NOT talking about jitter)

 

Based on a cost of 50-60 EURO it is a cheap solution.

 

Torben

 

Honestly save yourself the heart ache and anxiety and use WiFi. 

 

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On 19/02/2024 at 10:42 PM, TRHH said:

I can highly recommend such a setup on "The Last Mile" -  measurement and test have shown SQ improvement

 

The measurements shown are not of the audio output of a connected audio device (dac/streamer etc).

 

They do not demonstrate an improvement in audio quality.

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11 minutes ago, Grizaudio said:

 

Honestly save yourself the heart ache and anxiety and use WiFi. 

 

 

Or simply don't worry about things which are not a problem, ie ethernet.

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2 hours ago, Grizaudio said:

 

image.png.fe95704e6a4b9adc093c665ece5ca7e6.png

The little isolating transformers in there are useful too. I made a S/PDIF isolating transformer using one of them a while back to break the ground loop between my PC and DAC and it still works to this day!

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On 20/02/2024 at 1:42 AM, TRHH said:

 

Based on a very interesting post:

"The choke cable – minimizing common mode interference over the last meter"

I have bullied this setup:

 

CommonModeNoiseFilter19022024A.thumb.jpg.af77a2952d1be2b8ea91cfc4e23f67e4.jpg

 

 

 

 

 

I can highly recommend such a setup on "The Last Mile" -  measurement and test have shown SQ improvement.

 

Torben

 

Thanks for posting this Torben. Very interesting.  Are you  able to describe what your setup was before and after the change and also any audible changes you perceived.

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Posted (edited)

This is the final setup that I am using on the last mile from FMC to DAC:

 

Audio15042024C.thumb.jpg.ebf66d1d076f1b681fc1fb8bef153b06.jpg

 

The setup look like this:

 

Audio15042024B.thumb.jpg.388060d010f049d793465385e4f0dd63.jpg

 

Torben

Edited by TRHH
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An very interesting lecture from Rob Watts, Digital Design Consultant, Chord Electronics:

 

"Digital is digital, it's all ones and zeroes. Except that, no it isn't. Beyond the fundamentals of the digital-to-analogue conversion process, there are a host of additional factors that can dramatically affect the sound of your DAC — and consequently, what you will hear through your signal chain. Discover how power supplies, analogue devices and circuit design, galvanic isolation, digital cables and more can dictate your listening experience. But most importantly, learn how sometimes, digital isn’t."

 

 

Torben

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6 minutes ago, TRHH said:

An very interesting lecture from Rob Watts, Digital Design Consultant, Chord Electronics:

 

"Digital is digital, it's all ones and zeroes. Except that, no it isn't. Beyond the fundamentals of the digital-to-analogue conversion process, there are a host of additional factors that can dramatically affect the sound of your DAC — and consequently, what you will hear through your signal chain. Discover how power supplies, analogue devices and circuit design, galvanic isolation, digital cables and more can dictate your listening experience. But most importantly, learn how sometimes, digital isn’t."

 

 

Torben

 

Yes that's all well and good but you haven't actually established there was ever a problem to solve with your dac.  

 

With respect you have assumed there was some audible problem caused by emitted RF, made a "solution" to which expectation bias and sighted testing makes you hear an improvement.

 

It should be noted that Rob Watts does make quite incredible (read beyond physics) claims regarding being able to hear differences at -200dB!

Edited by March Audio
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20 minutes ago, TRHH said:

This is the final setup that I am using on the last mile from FMC to DAC:

 

Audio15042024C.thumb.jpg.ebf66d1d076f1b681fc1fb8bef153b06.jpg

 

The setup look like this:

 

Audio15042024B.thumb.jpg.388060d010f049d793465385e4f0dd63.jpg

 

Torben

Those tight bends in the cable probably introduce more problems than the rest of the odds and sods claim to solve..

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I started watching the video, managed to get past the section about jitter which is non problem in any well designed current DAC but once he started talking about audible levels of intermodulation distortion being stopped by solid core mains cable I really lost the will to live.

 

IM is easily measureable and I have never seen any data which indicates RF coming through the mains had created audible levels of IM in competently designed kit.

 

It's ironic that class d amps powered by switch mode power supplies, both of which are fundamentally RF noisy, are some of the best performers in regard to IM.

Edited by March Audio
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Thanks for that Torben,  I note you have chosen to retain the AIM NA9 prior to your fibre module.  I have the older NA7 cable and like it very much. Have you tried without the NA9 and if so can you describe any difference you have noticed.

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23 minutes ago, bob_m_54 said:

Those tight bends in the cable probably introduce more problems than the rest of the odds and sods claim to solve..

 

No - UltraFlex Cat.6A patch cable allows significantly smaller bending radii compared to standard PVC and standard LSOH cables

 

Torben

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The video makes extraordinary claims.

 

At 15:22 He starts to talk about what level of noise floor modulation is audible.  He states that it doesn't matter how small it is, it's audible.  " at levels of minus hundreds and hundreds of dB"

 

This statement has no credibility, is beyond physics and human perceptual limits - limits which have been well understood, researched and tested for many, many decades.

 

He offers no evidence or data, objective or subjective, to support his claims.

 

Later in the video he claims to be able to hear differences at the -350dB level.

Edited by March Audio
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2 hours ago, TRHH said:

 

No - UltraFlex Cat.6A patch cable allows significantly smaller bending radii compared to standard PVC and standard LSOH cables

 

Torben

 

No, I'm afraid that is not correct, it doesn't allow a smaller radius than any other cable of the same diameter; bend radius is a function of diameter.

 

Just because a cable is flexible does not mean it can't push the twisted-pairs out-of-spec for bend radius. There is no correlation between cable flexibility and resisting the standards for minimum bend radius to conform to specification.

 

ANSI/TIA standard guidance on minimum bend radius for copper Ethernet is 4x the outer diameter of the cable for both solid core and stranded-copper as the minimum bend radius advised.

 

The specs I could find for generic termed 'ultraflex' suggested a minimum OD of 3.8mm although the cable in your picture looks a lot thicker than that when compared in scale to the Ethernet plugs. If we take 3.8mm then using the constant from ANSI/TIA to derive the minimum radius, we get 15.2mm. So any full-circle with an inside diameter of under 30.4mm is out of spec for bend radius.

 

It's clear that with a ferrite toroid of 61mm as per the original schematic, that each of the UTP turns around the toroid in the picture are well beyond tolerance for bend radius specs.

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3 minutes ago, TRHH said:

No - this is not the case with the cable. That is why I am using it.

 

Torben

 

Sorry Torben, you may be well intended with this, but it is still misinformation. Manufacturing specs and standards specs are not to be conflated. You cannot alter the standards. Regardless of sheath flexibility, the twist-rate is part of the standard and pulling those twists through a tight-enough turn will render them non-compliant and susceptible to worse crosstalk outcomes.

 

There is no issue with you, or anyone else, playing until your heart's content on all of this stuff, but it is right to highlight that it will take any cable out of spec when wound so tightly. Just imagine anyone who might have spent hundreds of dollars on an Ethernet cable claiming audiophile credentials that then tries to replicate this without appreciating that even if they subsequently disassemble the contraption, their cable will be out of tolerance after being stretched (stretched, as in taken through tighter turn radius than TIA/ANSI standards advise) through such physical contortions and then straightened-out again. It will be like a spring taken beyond its yield point. I doubt you will want to provide a warranty for anyone following such advice, so I am doing what is the right thing to do by other users and by StereoNET in advising caution.

 

I'll state again, even your thin, flexible cable, based upon scale observation in your picture appears out of spec now, regardless of what the manufacturer has said.

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