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mansr

Cable differences are real

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For the fun be complete do you mind sharing instruments used: Noise generator or AFG and Spectrum Analyzer ?

Thanks.

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16 minutes ago, Arpiben said:

For the fun be complete do you mind sharing instruments used: Noise generator or AFG and Spectrum Analyzer ?

Both are part of a Tektronix MDO3024 scope.

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Yes.  Cable differences are real.  

But remember that no well constructed cable (what ever the price) is "better" than any other cable.  The cable that sounds better to your ears in your system is the best cable.

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I don't have the technical background, so I'm just going to try a little logic.  The cheaper bunch of cables are most likely the ones with the "boring" and similar response.  My reasoning for this is that companies selling inexpensive cables don't have the time (labor) or ability (materials costs and expensive machinery) to make anything unique, thus will be buying the underlying cable from one of the mass-producers such as Belden, Nexans, Southwire, Mogami, etc. who have the experience, expertise, equipment, and economies of scale in their production to do the most advanced construction affordably, such that other companies can re-brand it or doll it up a touch with a sheath and still make a profit without charging a fortune.

 

A strange (not necessarily "bad" in audio frequencies, but outside the norm of the above "cheap" rebrands of mainstream cable/wire components) test result could be from AudioQuest, as they charge enough money for the majority of their cable offerings to subsidize the most bizarre construction.

 

The very worst result seems likely to be from a company whose products are purely the result of a "cable designer," who may have no understanding whatsoever of the best electrical properties and construction techniques to maximize signal and minimize interference for a given application.  "Oh, if this works for this tonearm cable to reduce noise, perhaps I should make a giant version of it for a speaker cable or power cord, or simply twist a hundred tonearm cables together and put it into a silk sheath with platinum connectors."  Such a "designer" probably won't have test instruments, or won't know how to use them properly, or won't care or believe it's necessary to even ensure basic performance (or consider extremely negative system interactions if their cable capacitance is extremely high, for example).

 

Anyway, whatever that is worth (probably nothing), that's how I see it by trying to use a little common sense and having no expertise in electrical matters/signal theory/whatever sciences are involved.  And of course, this doesn't address sound.  It's always possible that the worst result from a technical standpoint will be the most pleasing to the most listeners.

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2 hours ago, mansr said:

Cable differences are real, and they can be measured. Rummaging through my cable box, I selected a few and measured their frequency response up to 125 MHz using white-ish noise.

 

These are the cables I used:

  • RG-58 coax, 0.5 m
  • RG-58 coax, 2 m
  • No-name cheap-looking single RCA, 5 m
  • No-name not-quite-as-cheap dual RCA, 10 m
  • No-name video (yellow plugs) single RCA, 1 m
  • Maplin Pro dual RCA, 0.75 m
  • Maplin Pro dual RCA, 3 m
  • Maplin (non-pro) single RCA, 1.5 m
  • AudioQuest Tower dual RCA, 1 m
  • iFi branded purple dual RCA, 0.5 m
  • 21 AWG zip cord, 13 m

 

Below are spectrum analyser screenshots for each of these cables, in random order. Your task is to guess which spectrum goes with which cable, as many or as few as you like. It's also OK to simply point and laugh at the more silly-looking ones. The noise generator spectrum is inherently a little rolled off, so bear that in mind.

 

  1. cable-01.thumb.png.51d078d7d8bf3261fa41fa28d2a5f4c9.png
  2. cable-02.thumb.png.87df0cb53a37acae56f514b51770a851.png
  3. cable-03.thumb.png.da817944c910cf33880fbd781733a607.png
  4. cable-04.thumb.png.51e1732cac801c75ca86020c76636353.png
  5. cable-05.thumb.png.4dfd046a9538a190b912771b2f2c76b9.png
  6. cable-06.thumb.png.ada818a7dd0d6f0c471349ff26527052.png
  7. cable-07.thumb.png.b9385512250d49c4235ab395cd2d8337.png
  8. cable-08.thumb.png.c518a84effd56d99300aed4ab10bbe1b.png
  9. cable-09.thumb.png.da61f0d6d16ac5a8e8ba316ca4979f70.png
  10. cable-10.thumb.png.10520b19091abc20d803b3731d139567.png
  11. cable-11.thumb.png.4f43d1490c4e314310a00f21048d3bbd.png

 

Have fun!

 

That's cool, now measure some USB cables up to 1GHz ;)

 

 

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1 hour ago, mansr said:

Both are part of a Tektronix MDO3024 scope.

 

Add a directional coupler  and a reference load for calibration, then sine sweep in the desired frequency range and you will get the Return Loss ( VSWR ) curve. 😉 

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I'd say:

 

6 = RG-58 coax, 0.5 m

3 = RG-58 coax, 2 m

1 = Maplin Pro dual RCA, 0.75 m

 

The rest, who knows?

 

Mani.

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Curves 8, 9 and 11 are typical of reflections. Now who is who and how it has been measured @mansr knows.

In terms of digital transmission it is not impossible that all listed cables sound same.

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If I had to guess, I'd guess 9 or 11 is the Audioquest. But I freely admit that's based largely on my bias against Audioquest (although a bias based in large part on the poor measurements of some of their equipment).

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1 hour ago, jabbr said:

Could you list the outside jacket diameters and colors for each cable?

I've updated the list with that info.

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1 hour ago, Arpiben said:

how it has been measured @mansr knows

Each cable was connected directly from the AFG output to the spectrum analyser input on the Tektronix MDO3024. Any settings not shown in the screenshots are instrument defaults.

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4 minutes ago, Ralf11 said:

BTW, did you guys know that Optical Cables are Directional?

That's because impurities in the glass act as tiny one-way mirrors.

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4 hours ago, tmtomh said:

If I had to guess, I'd guess 9 or 11 is the Audioquest. But I freely admit that's based largely on my bias against Audioquest (although a bias based in large part on the poor measurements of some of their equipment).

I like the way you're thinking, whether your guess is right or wrong.

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4 minutes ago, jabbr said:

My guess is that the cables with thicker and multicolored jackets will have worse performance :) 

That would be a fair assumption, but in this instance it isn't entirely accurate.

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price/foot on the cables will be a strong correlate of poor performance

 

possible skewed kurtotic distribution tho for ultra-cheapos

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48 minutes ago, esldude said:

I plan on having some made in the zero g of the international space station.

 

'Microgravity', not 'zero g' - common misconception 😏

 

Mani.

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2 minutes ago, Ralf11 said:

price/foot on the cables will be a strong correlate of poor performance

I don't remember the cost of most, and several were "free," the Audioquest included.

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3 hours ago, mansr said:

Each cable was connected directly from the AFG output to the spectrum analyser input on the Tektronix MDO3024. Any settings not shown in the screenshots are instrument defaults.

 

Clear that you didn't use any directional coupler, thanks.

Direct from AFG Output (BNC F) to RF Input (N F) it is simply not possible without adaptors.

On top of RF Input N->BNC  adaptor you probably also used  banana/BNC and RCA/BNC ones.

Anyhow it doesn't change the game and let me try my luck for the fun.

 

11 = 21 AWG zip cord, 13 m, 2.0 mm, black

9 = Fi branded dual RCA, 0.5 m, 3.7 mm, purple

8 = AudioQuest Tower dual RCA, 1 m

3 & 6 = RG58 coax

 

 

 

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