Ethernet Cables, Audiostream test...

[Daudio]

Softsel/Merisel. 13 years from 1980 to 1993. Met a ton of computer industry luminaries along the way as I was a product acquisitions director for a long time.

 

Ah, sorry, not familiar with them. I was in the Plug-Compatible equip. repair business from 1973-1980 (CDC, Comma, Amdahl) and thought it might be one of the various leasing companies of the (short-lived) time...

 

I'm not sorry you missed the Paul Allen gig, you might have made a lot of money, but that part of your soul that craves innovation and quality might have been sorely deprived

[Quest]

Quest- it is entirely possibly that in most systems, ethernet cables make no difference at all. It is also possible that your system has some equipment sensitive to interference along the same lines as a bluetooth receiver.

This, I may agree with. However, every system I have visited to tune so far on this issue, can discern differences.. so I admit I am biased.

 

What I keep repeating though, is that ethernet or network issues are probably not that important at all since most people haven't even done the basics.. focus on what matters more first.

 

It is also possible, as you suggest that only very high end systems can-for lack of a better word- resolve well enough to present those differences.

This I disagree with. I have heard the same differences on entry level gear too.

Maybe the word 'transparent' can be used here.. what I mean being having very low coloration in the system. Not the same as 'neutral' sounding.

 

One of my good friends owns a setup that is less than 10x the price of mine, and the differences are every bit as discernible.. it's my personal belief that you can get well designed entry level gear to sound almost as good as high end gear (there will still be differences, but on an increasingly steep price/performance ratio), the more limitations you remove from the system. I start to believe the amount I paid for my gear may not have been necessary, but I already own it anyway, and I bought it to take a 'shortcut' rather than having to deal with those issues back then.

 

I feel sometimes higher end gear tends to have so much over-engineering because they try to solve issues for you - e.g. remember power amps with in-built regenerators? Well, if you improve the electricity at home, that becomes little benefit vs a similar design without that.. just an example.

 

 

Happy new year!

[KurtBJC]

Hi, there, all. I'm Kurt Denke, owner of Blue Jeans Cable in Seattle, WA. I saw this thread and thought I'd throw in a few observations relating to some of the things people have said here.

 

First, on the Megabits = Megahertz thing: not quite. Remember that one "cycle" (if you're an old guy) or one "Hertz" (if not so old) is a swing from the baseline up, then back through the baseline, down, and back up to it again. What that looks like is not one bit, but two: a one and a zero, if "plus" is one and "minus" zero. For this reason, the convention is, when thinking in frequency-domain terms, to regard the frequency of a binary bitstream as one-half the bitrate, so 100 Mbps would be 50 MHz, for example.

 

But it's a bit more complicated than that still, because most Ethernet signals are not sent in a straight ones-and-zeros format. There are different encoding structures which use multiple voltage levels, the most extreme of these in general use being PAM-16 which has sixteen different voltages. This is why we find Cat 6a cable, which is supposed to deal with 10 Gbps, tested only to 500 MHz which would equate to 1 Gbps/pair.

 

The relevance of the frequency range is a bit more complicated, too, by the fact that digital signals are sent in something approximating a square wave. It's impossible to send actual square waves, but the transitions are more sudden than in the pure sine wave which we think of when we think of a diagram of a cycle graphed against time and voltage, and this suddenness is important because it helps us to correctly measure voltages and/or time the transitions. Now, a square wave can be represented as the sum of the primary frequency and lesser-amplitude doses of all of the odd harmonics (e.g., the third, fifth, seventh, ninth, and on to infinity...) thereof; and the behavior of the cable actually shows this -- one reason it's hard to push digital signals through cable at distance is that attenuation increases with frequency, so the higher-order harmonics effectively just disappear. But much of the energy in the augmented "shoulders" of the bit is in that third harmonic. So you want a cable which performs well at the fundamental, and that performs well at the third harmonic at least, if you want to get these transitions through well. That's why, for example, 3G SDI cable is now sweep-tested to 4.5 GHz -- the third harmonic of the 1.5GHz fundamental of a 3 Gbps stream.

 

Some mention was made above of our Cat 6a cable and its floating shield. The floating shield is a bit of an odd critter, and it's not something one sees in a lot of applications. The reason it's there is that in Cat 6a we are concerned not only with crosstalk within the cable but also with "alien" crosstalk, which gets in from neighboring cables in a cable tray. Remember that this stuff is really specified with data centers and the like in mind, where there may be dozens of cables running together in close proximity -- that's why as we get up into higher bitrates alien crosstalk, which is not much of a problem in Cat 5e, becomes a big issue.

 

That floating shield is not really a general-purpose shield, and the fact that hum can be induced through it is no surprise. The function of the shield is to manage alien crosstalk, and it does this by acting as a sort of reflector and dissipator--the idea is that crosstalk hits the shield, flows along it, and dissipates itself, burning up in resistance and/or cancelling out with other crosstalk flowing in the shield. One of the odd consequences of this is that where, with conventional shielding, one wants the shield as heavy as possible for high effectiveness, this shield must be just thick enough--because we want the resistance of the shield to help attenuate the crosstalk, which a thicker foil would actually do less welll. When looking at a floating shield on a Cat 6a cable, one needs to discard a lot of the conventional notions of what it is that makes for good shield effectiveness. If this were not primarily an anti-alien-crosstalk shield, we'd expect it to be thicker; we'd expect it to be tied to ground at both ends of the cable; and if it were expected to deal well with low-frequency, high-energy noise, we might expect the foil to be overlaid by a nice heavy copper braid. There are products like that out there, too -- e.g., Belden's "DataTuff" cables.

 

There are of course people who prefer to use conventionally-shielded Cat 5e, 6, and 6a cables. For whatever reason, in Europe shielded Ethernet cables are very popular, and in the US not so much. Common mode noise rejection on well-made Cat 6 and 6a cable is really superb, so if the sending and receiving circuits are well balanced, a shield tends not to be all that relevant. Alien crosstalk presents special problems because of the proximity of the source, the similar or identical data rate of the source to the signal interfered with, and basic problems of cable layout -- if you've put a dozen runs of the same cable into a tray together, then there are only four lay lengths involved and so every pair in the tray has eleven neighboring pairs that are running at the same lay length. This is problematic for crosstalk because one assumption on which common mode noise rejection rests is that noise will hit the cable symmetrically; but when the source of the noise is twisting at the same rate as the receiver of the noise, it is anything but symmetrical.

 

Kurt

Blue Jeans Cable

[Paul R]

Hi Kurt- thanks for posting that, I really enjoyed reading it. And welcome to CA!

 

So- the big question- do ethernet cables make a difference in your audio system?

 

(grin)

The only thing I was not sure of in your posting, by the way, is your explanation of data rate. I have always understood ethernet signaling to be pulsed, not a sine wave. More, as you say, like a square wave signal. A 1 gigabit per second connection sends up to 1 billion pulses (bits) in a second. Full duplex, 2 billion. (adjusted to the correct power of two of course.)

 

Slower data rates are realized because of lack of activity, queuing delays, signaling overhead, etc.

 

It is quite possible I am wrong on that, but I think that understanding is correct.

 

Paul

[KurtBJC]

So- the big question- do ethernet cables make a difference in your audio system?

 

Oh, heck. You know, I actually have no experience with audio over ethernet--I think it is fair to say that in any application it's good to have well-made product that actually meets spec, and our recent review of ethernet cables found that a horrifying number of them not only don't meet their stated spec but don't meet the 5e spec either. One cable we tested, allegedly a "Cat 6," failed return loss at 5e by 8 dB, and I would not want to rely on that for any data, at any non-negligible speed. Could it make a difference? Yeah. Does it often, in practical fact, make a difference? Dunno. I would not spend a lot of money on Ethernet cables; but being sure you buy something good (not necessarily expensive) can be important.

 

I have always understood ethernet signaling to be pulsed, not a sine wave. More, as you say, like a square wave signal. A 1 gigabit per second connection sends up to 1 billion pulses (bits) in a second. Full duplex, 2 billion. (adjusted to the correct power of two of course.)

 

Well, sort of. I think you and I may have the same thing in mind. Yes, the idea is to more or less instantaneously transition between voltage states, holding the voltage state until the next bit begins. That's not what I would term "pulse," which to me implies bursts with spaces between. And it transitions, of course, both up and down. The idea is to generate something akin to a square wave, but an actual square wave is not attainable. If you've ever looked at an "eye pattern" from an HDMI signal, that's the sort of thing (though in an eye pattern the ups, downs and sideways traces are all laid over one another) -- the transitions are sharper than a sine wave but less sharp than a square wave.

 

Slower data rates are realized because of lack of activity, queuing delays, signaling overhead, etc.

 

Yes, true. And one also gets slower effective data rates if packets need re-sending, or if the signal quality is so bad that the whole system downshifts to a lower data rate. But the "native" data rate is the same in all these cases other than the downshift -- when the data are flying, they do it at the specified rate, but there are times when they're not.

 

Kurt

[Paul R]

Oh, heck. You know, I actually have no experience with audio over ethernet--I think it is fair to say that in any application it's good to have well-made product that actually meets spec, and our recent review of ethernet cables found that a horrifying number of them not only don't meet their stated spec but don't meet the 5e spec either. One cable we tested, allegedly a "Cat 6," failed return loss at 5e by 8 dB, and I would not want to rely on that for any data, at any non-negligible speed. Could it make a difference? Yeah. Does it often, in practical fact, make a difference? Dunno. I would not spend a lot of money on Ethernet cables; but being sure you buy something good (not necessarily expensive) can be important.

...

...

...

Kurt

 

Honestly? I tend to use fibre for important or long distance runs. Light has its own issues, but it is effectively immune to pretty much all the issues like crosstalk and such.

 

I do agree that reasonable cost and good quality are important in cables. Actually, I have a few of your cables - since they are available on Amazon with Prime (i.e. free 2 Day) shipping. I have to admit though, mentioning "cables" around here is like waving a whole flock of red flags at a bunch of bulls...

 

-Paul

[KurtBJC]

Fiber's nice, yes. Glass fiber, anyhow; POF isn't so great. I'm planning on getting some fiber patch cords onto our site in the not-too-distant future. Glad to hear you've got some of our cables! We do try to get them into every household...

[Paul R]

Do some nice decent glass TOSlink cables for the home market, please!

 

Fiber's nice, yes. Glass fiber, anyhow; POF isn't so great. I'm planning on getting some fiber patch cords onto our site in the not-too-distant future. Glad to hear you've got some of our cables! We do try to get them into every household...

[KurtBJC]

Do some nice decent glass TOSlink cables for the home market, please!

 

Now, there's a mystery. I have looked and looked, at trade shows, through vendor catalogs, and everywhere I can think of, for glass that can be used for TOSlink. I know that some vendors claim to sell them -- and yet everyone I have ever talked to in the glass fiber business tells me that it's nonsense, and that you can't do it because the aperture is all wrong. POF is huge by comparison to any glass optical fiber I've seen, and you've got to have a big aperture at the source or you get hardly any of the light. I have no idea how to do it--it seems as though you'd need a whole lens assembly just to focus the big source light down to a small aperture, and then another to take that and spread it out at the other end.

 

Now, maybe someone has a way to do that, or some sort of wacky glass fiber I've never seen offered anywhere -- but I'm not too sure. I have half a mind to buy some glass fiber TOSlink cables and cut 'em in half to see if they're actually POF.

 

Now, if it can be and is done, the only real advantage would be attenuation. It'd be a lot easier to get signal to travel long distances. But the bitrate in TOSlink is so slow that even the not-so-good attributes of POF are just fine for it, so long as the run isn't too long.

 

Kurt

[Audio_ELF]

Fiber's nice, yes. Glass fiber, anyhow; POF isn't so great. I'm planning on getting some fiber patch cords onto our site in the not-too-distant future. Glad to hear you've got some of our cables! We do try to get them into every household...

Kurt - POF being Plastic Optical Fibre (or something similar) and not, I assume, Pakistan Ordnance Factories?

 

Just a second thing - as a manufacturer I believe Chris requests you have a signature explaining who you are.

 

Welcome to the site.

 

Eloise

[KurtBJC]

Kurt - POF being Plastic Optical Fibre (or something similar) and not, I assume, Pakistan Ordnance Factories?

 

Pakistan Ordnance Factories tend to be lossy for digital audio transmission, so yes, Plastic Optical Fiber.

 

And thanks for the note re: signature. For some reason I cannot figure out where one inserts a signature--been through the profile and do not see it. So, dumb question, undoubtedly with extremely obvious answer: how do I do that (other than, of course, manually on each message)?

 

Kurt

Blue Jeans Cable

[Paul R]

I'm not quite willing to cut up my Silflex glass optical Toslink cable to prove it, but I would expect there to be glass and not plastic inside it.

 

Amazingly enough, it actually does sound a lot better than a $0.51 plastic Toslink cable from Amazon...

[KurtBJC]

I'm not quite willing to cut up my Silflex glass optical Toslink cable to prove it, but I would expect there to be glass and not plastic inside it.

 

Well, there certainly should be. But if there is, plainly they (and a few others) know something about this which nobody I've ever met in the glass fiber industry knows. I'd dearly love to know, but the call for long-run TOSlink isn't very great and the easiest thing to do is just convert to S/PDIF in most cases.

 

Kurt

Blue Jeans Cable

[Paul R]

Greatest call in the audiophile market is for short run cables- half meter, meter, possibly up to 3 meters I think. The long run TOSli k is much more the A/V guys, and that seems to be mostly HDMI these days. YMMV.

 

 

Well, there certainly should be. But if there is, plainly they (and a few others) know something about this which nobody I've ever met in the glass fiber industry knows. I'd dearly love to know, but the call for long-run TOSlink isn't very great and the easiest thing to do is just convert to S/PDIF in most cases.

 

Kurt

Blue Jeans Cable

[Daudio]

Now, there's a mystery. I have looked and looked, at trade shows, through vendor catalogs, and everywhere I can think of, for glass that can be used for TOSlink.

 

Kurt.

 

It was my impression that:

...there are glass TOSlink cables available for audio use

...the superiority of glass is due to the better optical termination (polish, perpendicularity)

...the biggest drawback to TOSink is the cheap, generic optical/electrical transceiver chips everybody uses

 

Have I been mislead ?

[KurtBJC]

Kurt.

 

It was my impression that:

...there are glass TOSlink cables available for audio use

...the superiority of glass is due to the better optical termination (polish, perpendicularity)

...the biggest drawback to TOSink is the cheap, generic optical/electrical transceiver chips everybody uses

 

Have I been mislead ?

 

Daudio:

 

I think there are indeed glass TOSlink cables available. I've been looking around again and what I'm seeing, in a few cases, are people who report that they are using bundles of many strands -- 280 in one case -- of glass fiber. That would be one way to deal with the huge difference in aperture. I have never seen bulk cable stock of that sort on offer, anywhere, and I know that if I were to have someone here (e.g., Telecast) make it for me it would be very costly. But it may be that there's a factory in China that does the stuff--I have yet to find anyone who does, however.

 

I doubt that glass is superior to POF for TOSlink in any respect other than attenuation. POF is rather lossy. The other advantage of glass would be that because the individual fibers are narrower, there are shorter reflection paths within the fiber and this will mean that transitions are better preserved -- sharper rise and fall -- than in POF. However, the data speed for TOSlink is so slow that I have difficulty imagining how that could matter. In data applications with high bitrates, however, that's a big deal; you want all of the photons traveling the same distance, ergo arriving at the same time.

 

I don't know anything about the quality of the optical/electrical transceiver chips. It is easy to imagine that quality issues there are relevant. I know that we do see that they vary considerably in how much attenuation they'll tolerate, but beyond that I don't know anything on the subject.

 

Kurt

Blue Jeans Cable

[Superdad]

Kurt:

Thanks very much for joining CA and posting such factual and informative information. It is refreshing too, for a manufacturer to be forthright in acknowledging the limits of their expertise. You seem to understand data transmission issues with cables very well. It is great to post about that and to let the rest of us try to integrate that with our personal experiences (both objective and subjective) as they relate to high-end audio.

 

By the way, as seen in this thread and elsewhere, I am a BIG fan of the BlueJeans Cable Cat6a (based on a Belden bonded pair 10GX wire assembly). In my critical audio data application it is blatantly obvious in the first 10 seconds of music playing how much better it is than the Cat5 cable it replaced--both 25 feet in my case).

 

I am still interested in trying a version of the same construction cable (Belden 10GX, 24AWG, bonded-pair) but without the foil shield. Kurt, does your Cat6 (versus the Cat6a) meet that description, or is it made from a lower series of Belden?

 

Also, perhaps you can post a bit about the supposed Cat7 standard." When I did my multi-cable/multi-construction shootout of 25-foot Ethernet cables, there was a cheap Cat7 in the mix, but it sounded worse than all the rest. Perhaps because I found out afterwards that it was a copper-clad-aluminum construction.

And some Ethernet cables have separate foil shields around individual pairs. Not sure what the standard those fall under or what the particular goal is. Just more "alien-crosstalk" suppression? (Isn't that what Han Solo was attempting in the bar scene when he told those creatures to shut up? ;-))

 

Regards,

Alex C.

 

P.S. I telephoned BJC a few weeks ago; I am assuming that it was you I spoke with.

[Audio_ELF]

And thanks for the note re: signature. For some reason I cannot figure out where one inserts a signature--been through the profile and do not see it. So, dumb question, undoubtedly with extremely obvious answer: how do I do that (other than, of course, manually on each message)?

Top right hand corner of the page is "Settings" then down the left side one of the options is "Edit Signature" (just under "My Profile".

 

It took me a few minutes to find and I thought I knew where it was...

 

Eloise

[KurtBJC]

By the way, as seen in this thread and elsewhere, I am a BIG fan of the BlueJeans Cable Cat6a (based on a Belden bonded pair 10GX wire assembly). In my critical audio data application it is blatantly obvious in the first 10 seconds of music playing how much better it is than the Cat5 cable it replaced--both 25 feet in my case).

 

Thanks! Glad to hear it. And, as you note, it is indeed a 10GX series cable. For people who are building networks, that's a relevant consideration because while these do meet spec and stand on their own just fine, there are some things about the 10GX system which they support as well. In particular, 10GX patch cord stock and horizontal cable have offsetting crosstalk characteristics -- the "worst" pairs for crosstalk in the patch match the best in the horizontal, and vice versa.

 

One other note re: it being a 10GX cable -- on a question you haven't asked but which people do ask -- while it is a 10GX series cable it does not correspond to any Belden part number you can buy, and it's not even the same stock as the Belden-terminated patch cords which Belden makes in Canada. There are a few patch cord stocks in Belden's custom-order range, and this is one of those.

 

I am still interested in trying a version of the same construction cable (Belden 10GX, 24AWG, bonded-pair) but without the foil shield. Kurt, does your Cat6 (versus the Cat6a) meet that description, or is it made from a lower series of Belden?

 

Our Cat6 meets that description in all respects except that it's not a 10GX cable. Here's the deal:

 

When we test Cat 6 assemblies at Cat 6a criteria, they ordinarily pass. In fact, they often pass with larger margins than the 10GX cable does. Now, if that's the case, why are they not deemed "Cat 6a" cables instead of mere Cat 6? The difference is this: all cables must, to be deemed compliant, be made from components which comply to the applicable component specs for the category, and THEN must also pass the return loss and crosstalk specs as assembled. Our plugs are 6a compliant, and our 6a patchcord stock is 6a compliant, but the regular "6" patchcord stock would have to meet 6a alien crosstalk standards to be a 6a compliant patchcord stock. I believe that this is the only reason that our "6" patchcords cannot be deemed "6a."

 

Now, as you will likely already have considered, this is completely irrelevant to you if you are not running the cable in a big bundle of cables. Alien crosstalk is all about what happens when these are run in close proximity to one another, and the standards are written with huge cable trays in mind.

 

Also, perhaps you can post a bit about the supposed Cat7 standard." When I did my multi-cable/multi-construction shootout of 25-foot Ethernet cables, there was a cheap Cat7 in the mix, but it sounded worse than all the rest. Perhaps because I found out afterwards that it was a copper-clad-aluminum construction. And some Ethernet cables have separate foil shields around individual pairs. Not sure what the standard those fall under or what the particular goal is. Just more "alien-crosstalk" suppression? (Isn't that what Han Solo was attempting in the bar scene when he told those creatures to shut up? ;-))

 

I don't know much about Cat 7, and I don't have a copy of the spec, but most of the cable I've seen advertised as Cat 7 seems very suspicious. First off, I'm pretty sure it is impossible to make an RJ-45 plug which is Cat 7 compliant -- there are Cat 7 connectors, but they look quite different and are not plug-in compatible (there are dual-purpose jacks, which will take either an RJ-45 plug or one of these Cat 7 plugs, but the RJ-45 mode is not intended to support Cat 7). To my understanding Cat 7 sees some use in Europe, but it's so rare in the USA that Belden doesn't even make it here.

 

Copper-clad aluminum? That's odd. It is true, however, that skin effect at these frequencies is very strong and so it shouldn't matter much what the core is. I am not sure, however, that there are not issues in drawing wire like that--plating depth is going to be meaningful, and you wouldn't want it to vary much.

 

The Cat 7 standard, as I understand it (again, I don't actually have a copy of the spec), does call for the pairs to be individually shielded. This will cut down on all crosstalk -- alien and otherwise -- but it makes connectorization more unpleasant, and it makes the impedance of the pairs a bit dicier to control because the shield affects the impedance and its wrapping cannot be done quite as consistently as the conductor-to-conductor spacing can be (not to mention drain wire--which messes with symmetry and spacing as well). I don't think I've seen any Cat 6 or 6a with individually shielded pairs, but there's nothing in the spec which would prohibit that sort of construction.

 

I telephoned BJC a few weeks ago; I am assuming that it was you I spoke with.

 

Not sure--could be, though.

 

Kurt

BJC

[Superdad]

Awesome reply Kurt--thanks! Be careful though, these forums can really suck the productivity out of your day (he says after 3 hours straight of this).

 

I just went ahead and ordered a 25-footer of your Cat6 (to compare with your Cat6a I already love) from Amazon (Prime gets it to me in 2 days with free freight, though I wish you would stock something other than black with them). I'll report if I hear any difference in my application.

 

As for Ethernet cables with individually shielded pairs: Oddly there is a Cat6a being sold by BetterCables being sold on Amazon that shows this (along with a braided outer shield) in a close-up photo. Amazon.com: Cable Matters Cat6a Snagless Shielded (SSTP/SFTP) Ethernet Patch Cable in Blue 5 Feet: Computers & Accessories See the fifth photo. I did order and try this cable but did not like it (sound--don't ask). One would think they would call it a Cat7, but as you say, RJ45 does not really fall under that.

 

And for "Cat7" and copper-clad-aluminum, take a look at this one: Amazon.com: KEYDEX 25ft CAT7 SSTP 600Mhz Gold-Plated Snagless Network Lan Ethernet Patch Cable - Blue: Computers & Accessories

The page says 27AWG stranded copper, but Keydex's actual product page (Keydex) say aluminum. And I have read about CCA used for cheap Ethernet cables.

I bought this one and it was the worst of the whole bunch!

 

Thanks for making the good stuff so affordable!

 

Ciao,

AJC

[KurtBJC]

If you have any of those still on hand and would like to know how they test, I'd be happy to test 'em for you. I am surprised to see individual shielded pairs on a Cat 6a, and especially to see what look like outward-facing foils (foil shields are usually bonded to mylar, and either have the conductive face in, or out, though there are also two-faced foils as well), in contact with one another and in contact with a braid. I would expect inward-facing foils as there can be squirrelly results when you've got shields touching each other at these frequencies, especially if they don't touch consistently from place to place. But it's hard to be sure, from the photos, exactly what the deal is. On the "Cat 7" one--I can't test it at Cat 7 but I certainly could see whether it passes 6a.

 

By the way, re: Black being the only color on our Amazon listings: we will be adding more colors. It's just that our experience has been that products start to sell on Amazon very slowly, so we don't want to load them up with dozens and dozens of items that might not sell. As the black ones pick up sales, we'll broaden the offerings.

 

Forums can indeed suck productivity out of one's days. Fortunately for me, though, public outreach is one of my jobs....

[Superdad]

Thanks for the reply and for the offer Kurt. But I sent back to Amazon all the cables that I did not like. That included another one from CableMatters, their UTP Cat 6.

 

Frankly I don't think you need to load Amazon up with a bunch of colors, just something instead of black might sell better. I bet blue is their most popular selling color of Ethernet cable.

Actually, with the very round, very large and stiff 7.3mm diameter of your Cat6a, of grown fond of the black. Makes it look like giant RG6! It's pretty serious stuff.

 

Forgot to ask if you have any comments regarding use of stranded versus solid conductor for high performance Ethernet cables. I know there are other tweaks on this forum who would be interested in the objective differences. Do some of the Cat standards specify solid core? I was kind of surprised (yet pleased) to find it with your Cat6a cable. I always thought that most Ethernet patch cords were made with stranded wire. Is that the case or have things changed?

[KurtBJC]

The TIA spec suggests, but does not require, stranded conductors for patch cords. But really, the flex life of solid copper conductors is excellent and I think that's unnecessary.

 

The biggest issue, performance-wise, is that impedance stability is ordinarily better with solid wire. Why? Well, it's a sort of a symmetry/topology issue. A solid wire presents a smooth rounded face to the outside, which means that when a cylinder of insulation is extruded over it, the insulation is very close to the ideal: equal thickness at all points. Think about it in cross-sectional slices of the cable and you see what this means: the relationship of the conductors of the pair to each other, and the amount of dielectric between them, is more consistent in the solid wire case. There are practical issues that can crop up as well; we tend to think of stranded wire as being extremely uniform, but any manufactured product really is not, and so we're not always looking at a really geometrically tight seven-strand bundle with a rounded hexagonal outer profile--we may have spacing within the strands, we may have irregular twist, and things like that which affect the shape of the wire.

 

When I talk about things like this, people tend to think it's a bit silly -- that it cannot possibly matter whether the strands are oriented just so or not. But high-frequency signalling is a strange world, and all kinds of dimensional tolerances that make absolutely no difference in the DC or low-frequency world start to matter. Considerations like these do cause impedance to be a little harder to manage in stranded cable, and when you have products like Cat 6a which are difficult to make compliant, little fractions of dBs matter.

[Superdad]

Great answer. Thanks again Kurt.

[Audio_ELF]

The TIA spec suggests, but does not require, stranded conductors for patch cords. But really, the flex life of solid copper conductors is excellent and I think that's unnecessary.

The problem with solid copper on patch chords is usually when you are stacking a dozen 24port patch panels in a cabinet and then adding cable management and then forcing the door closed*...

 

In domestic environment I doubt it is likely to matter

 

*stranded patch chords tend to bend with smaller radius without kinking!