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What's the consensus on ethernet cables?


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On 2/5/2019 at 6:13 AM, RCG said:

Anyone with the full knowledge and understanding of the OSI model and how Ethernet works knows that just having a good, solid cable is plenty good enough.  Completely different animal from the likes of USB in how it works. 

 

They both transport digital signals. I would like to hear your explanation why so different 😀

 

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42 minutes ago, Axial said:

Made in the USA

▪ http://beldenblog.com/made-in-the-u-s-a-not-as-easy-as-it-sounds/

I have zero clue about Ethernet cables made in China, India, Africa, Venezuela, Russia, Saudi Arabia, etc. My Belden Ethernet cables I use in North America

That's not Belden Electronic Wire and Cable! 

It's some sort of political blog.

* * * * * * * * * *

This is the real Belden Blogs:

https://www.belden.com/blog

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8 hours ago, mansr said:

I wish people would stop using that phrase. As you well know, electric current flows through all possible paths in inverse proportion to their resistances.

Fully agree.  Its tiny inconsistencies that can muck it all up.  Poor insulation, bad solder, conductor ran through fast dies with inconsistet diameter and crystal boundaries.  I was brushing up on grounding the other day and reread about induced voltage to grounds and shielding. That is why I asked if signal is AC or DC.  If its AC, improperly built, it can create voltage and ground loops.  

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11 hours ago, mansr said:

I wish people would stop using that phrase. As you well know, electric current flows through all possible paths in inverse proportion to their resistances.

I am specifically talking about return current path :

http://www.sigcon.com/Pubs/news/8_08.htm

Even Dr Howard Johnson uses that terminology as do many others involved in signal integrity/high speed design.

So I would say that the terminology used in this situation is correct and is to illustrate how return path current flows, a critical part of understanding signal flow.

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17 minutes ago, marce said:

I am specifically talking about return current path :

http://www.sigcon.com/Pubs/news/8_08.htm

Even Dr Howard Johnson uses that terminology as do many others involved in signal integrity/high speed design.

So I would say that the terminology used in this situation is correct and is to illustrate how return path current flows, a critical part of understanding signal flow.

To be totally correct the terminology should be the return current path is always the path of least impedance, at low frequencies (<low kHz) the path of least resistance dominates as frequency increases (low kHz +) the path of least inductance dominates...

Happier😀

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13 hours ago, R1200CL said:

 

They both transport digital signals. I would like to hear your explanation why so different 😀

 

 

From what I understand about USB Audio (which may be wrong), USB Audio (as opposed to USB) doesn't implement error correction natively via a transport layer, but relies on chunks of the data stream to be transferred within a specific time frame (clock). This can cause errors.

 

Ethernet usually has a network and transport layer as part of a protocol stack that can guarantee the correct transmission, error correction, and retransmission of packets. (My rusty networking background: development of ISO protocol stacks, X.21, X.25, X.400, X.500, SDLC/HDLC).

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2 hours ago, marce said:

I am specifically talking about return current path

Current always flows in a closed loop, and the same rules apply in all parts of said loop.

 

2 hours ago, marce said:

That's talking specifically about a high-frequency signal in a trace over a ground plane on a PCB. As it happens, the inductance increases considerably with distance from the signal trace, confining most of the return current to a small area directly beneath it. This is contrasted with the DC case wherein the return current is rather spread out with the highest density around the most direct path between the two points, regardless of the "forward" conductor routing.

 

Now, the present context was cables and their shielding. PCB design principles aren't really a good fit here, although the same laws of physics of course apply.

 

1 hour ago, marce said:

To be totally correct the terminology should be the return current path is always the path of least impedance, at low frequencies (<low kHz) the path of least resistance dominates as frequency increases (low kHz +) the path of least inductance dominates...

You're still assuming there is a single path that dominates. This may or may not be the case in any given situation.

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5 hours ago, marce said:

To be totally correct the terminology should be the return current path is always the path of least impedance, at low frequencies (<low kHz) the path of least resistance dominates as frequency increases (low kHz +) the path of least inductance dominates...

Happier😀

Actually, the return current will take all available paths. Inversely proportionally to the impedance of that path. Different paths will have different impedances at different frequencies.

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9 minutes ago, jabbr said:

Ha ha, I suspect he knows that, and as he says, he is using terminology which assumes this. It’s hard to convey a 3D model in a few words which is why we use simplifications for the purposes of discussion 

Of course marce knows how electricity works. My objection to the "path of least resistance" term is due to the misunderstandings I've seen it cause with people lacking an engineering background.

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3 hours ago, mansr said:

 

You're still assuming there is a single path that dominates. This may or may not be the case in any given situation.

 

You may feel free to correct me if I am wrong, but IIRC, at any particular instant in time, there is always a path that dominates. Perhaps not by much though. 🤪

 

Since everyone is picking nits here. And I honestly do not see the applicability here unless the DAC is plugged directly into an ethernet port. And perhaps not even then. 

 

Ethernet transmissions are basically at RF frequencies, ignoring little things like 4D encoding using Pulse Amplitude Modulation, Power over Ethernet, Full Duplex operation, etc. Or at the other end, single pair connections (PHYs) from the automotive world some folks are using for audio. 

 

The physical transport of data over ethernet is complex.  But it is data being transmitted, not music. Different rules apply. 

 

I am not convinced that the differences some folk hear with ethernet cables is purely some kind of expectation bias, but the evidence that might be the case is compelling and should not be dismissed. On the other paw, it ain’t worth stomping on someone’s dream either. 🥜

 

 

Anyone who considers protocol unimportant has never dealt with a cat DAC.

Robert A. Heinlein

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3 hours ago, mansr said:

Current always flows in a closed loop, and the same rules apply in all parts of said loop.

 

That's talking specifically about a high-frequency signal in a trace over a ground plane on a PCB. As it happens, the inductance increases considerably with distance from the signal trace, confining most of the return current to a small area directly beneath it. This is contrasted with the DC case wherein the return current is rather spread out with the highest density around the most direct path between the two points, regardless of the "forward" conductor routing.

 

 

Better have a go at this guy and all, I can't believe he's using the same terminology I used...😀 As punishment I shall read some Synergistic Reasearch White papers ...

tonight.

http://www.emcs.org/acstrial/newsletters/fall08/tips.pdf

 

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1 hour ago, mansr said:

I have come across people on this very forum believing that if you connect two resistors, 1 Ω and  2 Ω, in parallel, all the current will flow through the smaller one because it provides the "path of least resistance."

If you ever run into someone like that again, just say: "Water in a pipe" 

 

Better to explain "path of least resistance" to a newbie and avoid the word salad that derailed this thread. 😎

Main System: QNAP TS-451+ NAS > Silent Angel Bonn N8 > Sonore opticalModule Deluxe v2 > Corning SMF with Finisar FTLF1318P3BTL SFPs > Uptone EtherREGEN > exaSound PlayPoint and e32 Mk-II DAC > Meitner MTR-101 Plus monoblocks > Bamberg S5-MTM sealed standmount speakers. 

Crown XLi 1500 powering  AV123 Rocket UFW10 stereo subwoofers

Upgraded power on all switches, renderer and DAC. 

 

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1 hour ago, mansr said:

I have come across people on this very forum believing that if you connect two resistors, 1 Ω and  2 Ω, in parallel, all the current will flow through the smaller one because it provides the "path of least resistance." That's what I'm trying to avoid. The sources you're citing are addressing an audience who already knows this isn't how electricity works, and such shorthand terminology is thus unlikely to cause any confusion.

I understand your point now, as said I was using the terminology only in reference to return current path, exclusively. The thing is with digital signals (and analogue) is understanding the return path for the signal, it is as critical as the signal and often some audiophile advice on grounding, signal returns etc. are at odds with what is required for a low noise system with maximum signal integrity. Often signal integrity is discussed, often with minimal reference to all the issues that have an effect on the signal, return path being a critical one. Trying to get across all the issues and develop a better understanding of signal propagation would IMO especially with digital get the point that "Bits are Bits" as well as the understanding that EMC (noise) and signal integrity are two sides of the same coin.

It's been an interesting little discourse.

One of the things that has bugged me regarding a lack of understanding of return paths with digital audio is clock modifications, both here and on DIY audio... To illustrate my frustration have a look at this link...

https://audiobacon.net/2018/09/28/the-linear-solution-ocxo-audiophile-switch-reference-ethernet-cable-the-missing-pieces-of-digital-audio/

The clock signal is connected by a single wire, the return path is going to have to meander round the board and return by one of the supply leads. Whilst a wiring issue, the problem and issues are best illustrated by a slot in a PCB ground plane. The lack of an intimate return wire for the clock creates a huge discontinuity in the return path, not only creating ground noise (at the fundamental clock frequency and its harmonics, to be avoided at all costs) but the clocks signal integrity will be compromised...

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18 minutes ago, audiobomber said:

If you ever run into someone like that again, just say: "Water in a pipe" 

 

Better to explain "path of least resistance" to a newbie and avoid the word salad that derailed this thread. 😎

 

I like the water analogy.  For example, volts is the "speed" or "pressure" of the river, amps is the "width/depth" of the river, etc.  Works for me anyways

Hey MQA, if it is not all $voodoo$, show us the math!

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I just want to make sure people see at least one important thing in marce's post above.

 

Once you get past DC resistance and the "Mansr Problem" of least resistance, you get to Level 2 of Misunderstanding.

 

Level 2 is that you have to use impedance for all AC signals.

 

But "Wait!  There's more!  The Word Salad Shooter of circuits shows us that is just Level 3.

 

You next need to realize that impedance has to be deconstructed* by freq. bands.

 

very low frequency signals that tend to follow the path of least resistive impedance and higher frequencies tend to follow the least inductive impedance path  (I removed the motivational "want to" and replaced it with "tend to") in marce's quote

 

 

* just a nod to Derrida for the liberal arts majors... (or as we say down in NoLa, Jock-Imo)

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46 minutes ago, Ralf11 said:

very low frequency signals that tend to follow the path of least resistive impedance and higher frequencies tend to follow the least inductive impedance path

The real misunderstanding here is that there's a simple distinction between AC and DC. In reality, the current for each frequency is distributed according to the various impedances at that frequency. Suppose you have a 10 Ω resistor in parallel with a 10 μH inductor with a low DC resistance. Low-frequency currents will go mostly through the inductor while high frequencies will mostly go through the resistor. At around 200 kHz, the current is split roughly equally between the two.

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