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Originally Posted by slim.a /img/forum/go_quote.gif
nick_charles,
Those are interesting measurements but they were made by people trying to prove that cables do not matter. So it is easier to choose which parameteres to measure and then find out (what a surprise) that capacitance, resistance, ... do not change the sound in an noticeable manner.
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As far as I am concerned the only measurements really worth making are at end-user parameters such as FR, Noise , distortion and so on. It may be interesting to speculate about the effect of other electrical properties but if they do not lead to potentially audible differences it is a bit pointless. However more important is whether any two cables are actualluy audibly different under strict conditions. In the article I linked to Gene DeSalla said the differences might be audible and this is where the "different" cables are really extremely different. It is always possible to make cables audibly different just wang in a huge resistor and that will do the trick. The question is whether any two "normal" cables of comparable gauge will be sufficiently different to be distinguishable. It is here that strong evidence is so far lacking. Strong evidence has to mean unsighted lsitening tests as sighted tests are just completely unreliable.
I am not convinced that DeSalla has an agenda, if you look at Audioholics they talk about hugh end stuff , they are not some hairshirt objectivist cult like MatrixHiFi. But, even if he does the differences form these extremely different cables are still very very small indeed.
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| Focusing on those few parameters to measure is like focuse on thd and SNR alone to review a DAC. If those two parameteres were the only important parameters in a DAC, the EMU 0404 usb should trash 99% of audiophile DACs. I have the EMU 0404 usb at home and listening to violins through it make them sound like synthetized computer sound compared to the audio-gd dac-19mk3 which doesn't measure as good. |
With respect if your comparison was sighted , without careful level matching and with a long delay in switching between units then all sort of bias and expectancy effects come into play.
I found that whe I compared my external DAC with my CD player using a switch box that the level difference was sufficient to make the difference obvious, even unsighted, the hotter DAC always sounded better. However when I adjusted the average levels to within 0.1db these obvious diffefrences disappeared in unsighted testing.
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| Those articles you linked tell that the direction of cable should not matter. Yet some people (say they) hear differences in using the cable in different directions even in digital cables. Are they crazy ? Not really. |
I have measured directipnal effects in analog cables, they were very small (0.001db or so) but they did exist and were consistent, bit 0.001db is not audible. I would not call crazy I would say mistaken and also unverified.
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| You can find here an old test done by stereophile on digital cables. They found out this : "The overall RMS jitter was 4050ps with the Wonder Link connected in one direction, and 2700ps with the cable reversed. ". So what some people seem to hear (before even knowing there was a measurement to prove it) has indeed a "measurable" proof. |
While 4ns is indeed really bad jitter in absolute terms there is so far no strong evidence to suggest that the diffetence between this and less, even sub-ns jitter is at all audible. No manufacturer has ever been able to provide blind listening test data to support the audibility of jitter of such levels even thye most pessimistic data from Benjamin and Gannon place audibility at around the 20ns mark for worst case i.e correlated jitter.
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| I am sorry for the digression, but I just wanted to remind that showing that x parameters tell that there is no measurable diffrence between different cables does not necesseraly mean that there aren't other parameters (maybe yet to be identified) that prove the opposite. |
Again, it is trivial to make a cable audibly different but you have to do it deliberately and always when you do this you make the cable worse by introducing FR errors. Cables are normally flat to at least 20K, even lamp wire is flat to 20K. As for (yet to be identified) I am sorry but this is magical thinking, and even if there were other unidentified electrical properties it would not matter as we can already measure FR, noise and distortion and so on perfectly adequately.
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| Here is a link to some tests done by empirical audio on there cables. If you look at figure 8 for example, you see that a cable that measures flat to 100khz (well above human hearing range) actually rounds off the leading edge of a square signal. So maybe we spend to much time analyzing frequency bandwith in a static manner and less time analyzing the signal in a dynamic matter (attack, decay, multiple signals, ...). |
I have serious questions about this article, I will fill this section in with my next edit.
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| From this result you can see that the 11 AWG barely stays linear through the audio range, falling off dramatically after 20KHz |
Er, no the response is within 0.05db at 20K, even according to the crude graph which I had to blow up to 3000% to view`properly, 20K is a point at which human hearing is incedibibly insensitive in any case and the drop to 40K is a mere extra 0.1db hardly something to lose sleep over and irrelevant for audio anyway !
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| The superimposed waveforms of Figure 2 show clearly that the leading edges of the squarewave are being rounded with the 11 AWG ZIP-cord, but the fast leading-edge is preserved in the Clarity7 waveform |
That is not how I see it. Both square waves are in fact rounded, but don't take my word for it. Load the graph up into any image editor and zoom it up a bit it is patently obvious that neither wave is square at the leading edge. But so what, this is a 9Khz square wave , how much square wave content is there in music anyway - hint none normally.
Fig 3 is an obvious bit of image doctoring, the grid lines have disappeared in several places !, If I mathematically process tha data I used for my cable tests the gridlines did not disappear. There is even a bad pixel at 106:120 !. But wait there is more. In the processed graph the curve of the cheapo cable descends down to 106:118. In the undoctored graph the curve never gets below 106:109. The curve has been shifted down by 9 pixels.
A 6% phase shift at 20K is irrelevant it is not humanly detectable.
The 1 microsecond transient response test, that is 1 cycle of a 1Mhz signal, that is relevant to audio frequencies that top out at 20K how ?
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| By the way I am no engineer but I find that it is unfortunate that many engineers (or so called engineers) tend to analyze what is easy to do (static measurements) and they don't try to think about the music we are listening to as a dynamic signal that needs probably new ways to measure (other than what is necessary for industrial applications). |
Music has frequency, time and amplitude characteristics. Analysing it is straightforward.
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| If we applied the same rules to musical instruments, we should not give that much importance to Stradivarius violins or Steinway pianos since they probably measure the same as much cheaper and avalaible instruments. |
Actually that is untrue, each instrument has physical properties such as the precise shape and size of the soundbox, the resonance of the materials used and so on that make for the differences between them.
