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High End Cables
Old 10th July 2014
  #241
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FabienTDR's Avatar
 

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Hey Yannick,

first of all, your DA/AD behaves as expected, noise around -108dB, and shows the typical converter Nyquist filter behaviour. Zero harmonic distortion. No measurable aliasing.

All 3 files are extremely close to each other, which can be quickly checked with a phase correlation-meter (just pan one file left, the other full right). On a first visual analysis, I can only detect very small differences at higher frequencies, but I am not sure whether it relates to a slightly increased noise floor at high frequencies or cables. I'll create proper frequency and phase plots in the evening. There are no obvious differences so far, but let's wait what the FFT says.
Old 10th July 2014
  #242
j_j
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Quote:
Originally Posted by nms View Post
Fabien already gave him the test file he wanted him to run and Yannick just posted the recording for him to analyze. I can understand if he doesn't want to start installing and learning software, going over powerpoints etc.
Well, he could take the opportunity to listen to the lecture, it's about 1.5 hours or so, follow it on the power point, and start to understand frequency analysis a bit better.

But no, nobody has to learn.
Old 10th July 2014
  #243
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Jerry Tubb's Avatar
 

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Quote:
Originally Posted by Bob Olhsson View Post
it doesn't need to cost hundreds of dollars.
My rule of thumb regarding cables has always been:

"Spend no more (or less) on a stereo pair of cables than you charge for an hour (or two) of mastering."

Keeps it sane... Less spiraling obsession about micro-nuances of pricey cable.

Presently I'm using a mix of Belden, Mogami, Canare, & even Monster,

but the posts about Grimm Audio TPR have tweaked my curiosity!

Cheers, JT
Old 10th July 2014
  #244
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Yannick's Avatar
 

Quote:
Originally Posted by Jerry Tubb View Post
My rule of thumb regarding cables has always been:

"Spend no more (or less) on a stereo pair of cables than you charge for an hour (or two) of mastering."

Keeps it sane... Less spiraling obsession about micro-nuances of pricey cable.

Presently I'm using a mix of Belden, Mogami, Canare, & even Monster,

but the posts about Grimm Audio TPR have tweaked my curiosity!

Cheers, JT
I would check out the new Gotham starquad. I am also not a believer in expensive cable. The Gotham is around 10 euro/m and in my book is more transparant than anything I have heard.
Old 10th July 2014
  #245
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Yannick's Avatar
 

Quote:
Originally Posted by j_j View Post
Well, he could take the opportunity to listen to the lecture, it's about 1.5 hours or so, follow it on the power point, and start to understand frequency analysis a bit better.

But no, nobody has to learn.
I thought I already responded to the misunderstanding concerning the test file.

I just am not into installing a software that is difficult to run on a Windows machine. I do not want to put too much time in that.

I do have a grasp of how frequency analysis works.
It is my understanding ffts do not have the same time resolution as our hearing, isnt there always a tradeoff between freq or time resolution ?

I will try to listen to the lecture...
Old 10th July 2014
  #246
j_j
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Quote:
Originally Posted by Yannick View Post

I do have a grasp of how frequency analysis works.
It is my understanding ffts do not have the same time resolution as our hearing, isnt there always a tradeoff between freq or time resolution ?
df * dt >= c where df is frequency resolution in Hz, and dt is time resolution in seconds. 'c' varies depending on how you define the limits of "resolution". It is at best 1/2 (for gaussian vs. line spectrum for an unknown signal), and can be much larger if you want, say, 90dB of rejection of a second signal.

So yeah, there's always a tradeoff. FFT's come in all shapes and sizes, however, so you can accommodate the ear's time/frequency response as well as you would like.

Speaking as someone who's solved this problem quite a few times, in the case of a cable you will not need to match the ear, using a longish FFT is much more likely to show up issues.

And Octave works fine on my W7 box, but it's your box and your time, so whatever.
Old 10th July 2014
  #247
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I can recommend PS Audio Transcendence and Reference balanced XLR cables. They made a difference. I now look for POCCC (or variants of) copper cables, which can be had for as little as $20. I read all the info on the PS Audio cables (I bought used ones, as new price was too high for me to warrant) and the science sounded sound. Also never heard a bad review of them, which gave me a little more confidence. I was not disappointed. I also have Choseal ones and some made up for me, with XLR's one end and TRS on other. All really good.

Good cables don't have to be expensive. Blue Jeans Cables are a good place to look.
Old 14th July 2014
  #248
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Ok, I found some time to analyze Yannick's test-runs.


I took the files and extracted the impulse tests. Or more accurately: the DA - cable - AD impulse response. For my tests, I decided to use an impulse length of 6404 (it's much larger than really required in our case).

All impulses where scaled to reach 0dB at exactly 5kHz and have been windowed with a Kaiser window (alpha = 3).

Here follows all 3 tests results:


AES 01

Impulse response (only the central ~100 taps are shown here)


Frequency response +/- 1dB, linear frequency scale


Frequency response +/- 1dB, log frequency scale




AES 02

Impulse response (only the central ~100 taps are shown here)


Frequency response +/- 1dB, linear frequency scale


Frequency response +/- 1dB, log frequency scale




Velox 01

Impulse response (only the central ~100 taps are shown here)


Frequency response +/- 1dB, linear frequency scale


Frequency response +/- 1dB, log frequency scale



First conclusion

It is clearly visible that we most of all measured the DA and AD converter's response. One can easily spot the modern ADA converter's linear phase Nyquist filter section tuned right above 20kHz + the subtle phase shift of the analogue Nyquist filter (in fact, it's just its "tail", the analogue Nyquist filter operates at a very high frequency, far outside human hearing limits).

So far, no surprises.

All three files have almost the same impulse responses and thus almost exactly the same frequency and phase response. The differences are extremely small and have typical white-noise properties (i.e. it is most probably noise).

All three cables have almost absolute transparent linear behaviour, if any!


Sine-sweep and IMD tests show absolutely no measurable traces of non-linearity (just open a spectrum analyser, set it to a large window size and look for harmonics/IMG products). Even the most minimal, inaudible form of non-linearity becomes very apparent on the scope, but these 3 files show nothing! (A good sign for Benchmark and a very bad one for cable voodoo)

I can share the impulse response if anyone is interested.
Old 15th July 2014
  #249
nms
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Quote:
Originally Posted by FabienTDR View Post
All three files have almost the same impulse responses and thus almost exactly the same frequency and phase response.
Almost the same impulse? It looks (and they should be) identical but all 3 are shown at different display ranges. Was this an automatic function? No way to have them all display the same?

For the FR it would be more useful to zoom in vertically to check any amplitude difference. Although, even if there was anything there at such microscopic levels it couldn't be reasoned that it would be audible at that level.
Old 15th July 2014
  #250
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FabienTDR's Avatar
 

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Quote:
Originally Posted by nms View Post
Almost the same impulse? It looks (and they should be) identical but all 3 are shown at different display ranges. Was this an automatic function? No way to have them all display the same?
Yes, it's been done manually, hence the slightly different range of the impulse response. It shows less than 1/100 of the full response anyway. Let me give it another try tomorrow.

Quote:
Originally Posted by nms View Post
For the FR it would be more useful to zoom in vertically to check any amplitude difference. Although, even if there was anything there at such microscopic levels it couldn't be reasoned that it would be audible at that level.
I can zoom in if you want, but we're already at +/- 1dB.
Old 15th July 2014
  #251
nms
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May as well zoom in a bit more on the FR to see if there's anything at all. Just for ****s & giggles.
Old 15th July 2014
  #252
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Yannick's Avatar
 

We can all have our giggles, but what is worrying me is that almost anybody can walk in here and hear an obious difference between the cables.

So, either the test setup is flawed or we need a different set of measurements.

As I posted before, in REW I was able to see a significant (?) difference between the IRs.
Old 15th July 2014
  #253
nms
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Quote:
Originally Posted by Yannick View Post
As I posted before, in REW I was able to see a significant (?) difference between the IRs.
I looked through the REW files and there was no significant difference to be noted anywhere.

Here's the impulse of each.. a blown up direct view of the waveform. They are identical:
Attached Thumbnails
High End Cables-velox.gif   High End Cables-aes02.gif  
Old 19th July 2014
  #254
mpr
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Call me crazy, but for short balanced cable runs, I prefer no shielding. Unbalanced is a different story...

I had been using Belden 1800f for 15 years and then swapped out a bunch of the Belden interconnects for unshielded Vovox cable and my first reaction was: "What is this BS about?!"

I am convinced that I am simply hearing more HF noise (air) on the Vovox cable and my ear likes it, interpreting it as more open and spacious.

How on earth would shielding make audio sound drier, with less apparent space? Impossible.
Old 19th July 2014
  #255
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Paul Gold's Avatar
 

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Quote:
Originally Posted by mpr3 View Post
How on earth would shielding make audio sound drier, with less apparent space? Impossible.
Possible. Capacitive coupling is between conductor and shield. With no shield connection there is no HF rolloff due to capacitive coupling. As long as the noise floor is low enough you're good, until a CB radio comes down the street.
Old 19th July 2014
  #256
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Piedpiper's Avatar
I know at least one other who prefers to minimize shielding in less at risk environments.
Old 19th July 2014
  #257
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Grant Ransom's Avatar
 

Quote:
Originally Posted by Yannick View Post
We can all have our giggles, but what is worrying me is that almost anybody can walk in here and hear an obious difference between the cables.
So... they notice an "obvious" difference when you swap the cables without telling them?
Old 19th July 2014
  #258
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FabienTDR's Avatar
 

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Quote:
Originally Posted by Paul Gold View Post
Possible. Capacitive coupling is between conductor and shield. With no shield connection there is no HF rolloff due to capacitive coupling. As long as the noise floor is low enough you're good, until a CB radio comes down the street.
Which rolloff? At line-levels? (it's a different story for speaker and instrument/mic interconnection).

As a mastering engineer, recording this effect should be a piece of cake, right? After Yannick seriously burned his nose, do you really want to give it another try?!

IMHO, you're just another victim of cognitive bias, as well as the million other things heavily affecting hearing such as hormone level, temperature and humidity/pressure, long term memory effects, illness, weed, alcohol even sexual activities and whatever.
Old 19th July 2014
  #259
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Paul Gold's Avatar
 

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Quote:
Originally Posted by FabienTDR View Post
Which rolloff?
The one on most cable spec sheets.
Old 19th July 2014
  #260
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sat159p1's Avatar
Quote:
Originally Posted by FabienTDR View Post
IMHO, you're just another victim of cognitive bias, as well as the million other things heavily affecting hearing such as hormone level, temperature and humidity/pressure, long term memory effects, illness, weed, alcohol even sexual activities and whatever.
+1

Old 19th July 2014
  #261
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Grant Ransom's Avatar
 

Quote:
Originally Posted by Paul Gold View Post
The one on most cable spec sheets.
You mean capacitance?
Old 19th July 2014
  #262
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Paul Gold's Avatar
 

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Quote:
Originally Posted by Grant Ransom View Post
You mean capacitance?
Yes. I explained what I meant above. We have some Totally Daft Readers.
Old 19th July 2014
  #263
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Indeed, we seem to.
Filtering is a function of the system made by the I/O circuits and the cable capacitance:
"Roll-off" wouldn't be quoted as a spec because it would depend on the system.
Old 19th July 2014
  #264
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Paul Gold's Avatar
 

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Quote:
Originally Posted by Grant Ransom;
"Roll-off" wouldn't be quoted as a spec because it would depend on the system.

Yes, that's my point. It takes a little bit of brain power to investigate the claim.
Old 19th July 2014
  #265
nms
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Quote:
Originally Posted by Paul Gold View Post
Yes, that's my point. It takes a little bit of brain power to investigate the claim.
It would take much longer cables than most people use in order to arrive at any perceivable HF roll off at line levels.
Old 19th July 2014
  #266
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Paul Gold's Avatar
 

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Quote:
Originally Posted by nms View Post
It would take much longer cables than most people use in order to arrive at any perceivable HF roll off at line levels.
Yes, if everything was working correctly. I can imagine some failure modes that could make that happen.
Old 20th July 2014
  #267
mpr
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Has anyone else experienced unshielded Vovox before, and heard what I am talking about? (or any other unshielded solid copper core cable)

I really was happy with the Belden and Mogami that Ive been using thru 3 marriages, but now I am confused because I trust my ears, even with my mind screaming, 'impossible!'.
Old 22nd July 2014
  #268
j_j
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Can I give you guys a couple of signals to run through your cable? Just run it at the native sampling rate (no up/down sampling except what your convertor always does), record it with the best bit depth you can, and post the file back?

Bandwidth is one such thing, there are others.
Old 22nd July 2014
  #269
j_j
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Can I give you guys a couple of signals to run through your cable? Just run it at the native sampling rate (no up/down sampling except what your convertor always does), record it with the best bit depth you can, and post the file back?

Bandwidth is one such thing, there are others.
Old 22nd July 2014
  #270
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I am not a dreaded cable changer, so I can't help you. I only said i thought mpr3's claim was "possible" as opposed to "impossible". I use a console from the 1970's with cable of unknown manufacture. The rest of the cable is a motley assortment. In the console I'm building I used Gotham because it has excellent shielding, it comes in grey, and 2pr fits in a Neutrik xlr boot.
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