[nick_charles]

Quote:

Originally Posted by Grizzlepaw /img/forum/go_quote.gif

Well, the differences were not audible to me. Also to see these differences you are zooming down to 0.0001 or 0.00005 second divisions (the scales are not the same for your last two segments).

Once you play this back at normal speed (as it were) any effects will be much harder to detect due to the masking effect of adjacent wave segments.
However you could run them through FooBar's ABX plug-in and see if they really are detectable, but you will have to trim the files to the same length and do a best effort alignment first or you could just tell from the file length. Let us know how you get on.

 

[Grizzlepaw]

I dunno. If I listen to the decay on both tracks, it sounds to me like left has a much smoother edge, and right has a much harder fall-off.

But that could just be my mind playing tricks.

I don't do much A/B listening, but to me it sounds like Left has more nuance.

dunno. I'm listening to it through in ear monitors right off my mac PC. So YMMV.

 

[unoab]

If you are going to post graphs and use them to draw conclusions also make sure you include the divisions on the y-axis also. For all we know you may be complaining about .02dB of difference in a silent section of the music.

If you want to use numerical data, like graphs of the WAV files make sure both amplitude and time information is visible. Then we can figure out both the approximate frequency that is present and its amplitude (only if there is a semi-sinusoidal shape to the noise). Objective data requires an objective evaluation.

 

[yotacowboy]

Quote:

Originally Posted by Febs /img/forum/go_quote.gif What I would like to see is two different .wav files (or lossless files) created with the same cable to see if the types of differences that you are observing happen even with the same cable.

exactly - otherwise the experimental design is somewhat flawed, but pretty easily fixable.

 

[nick_charles]

I have just spent the last 2 and a half hours trimming and editting the two wav files. The differences are still there but once you align the files properly so that you can see them against each other the differences are really really small.



In the picture above each time division is 1/10,000 of a second. So you see about 4 samples per division. The Y-axis is amplitude ranging from +1 to -1, it is hard to quantify percentage differences but they are small.

 

[unoab]

One thing I have been wondering about, if you were to take one test signal and feed it to the left ear, and feed the other signal to the right ear (assuming mono recordings), then if they were exactly the same you should get a perfect mono image directly in front of you. The fun comes when both signals vary from each other, based on the difference in both amplitude and phase it will create the effect of an inter-aural intensity and phase/time difference, thus locating the sound off axis of the center (soundstage? not quite..). This will be able to tell us if there is a difference in the recordings, since what is better at picking up subtle acoustic cues (read differences) than our auditory system?

I don't think this will solve the problem of which cable is better, but it could possibly give an idea of where the differences lie between both of the cables, if it shows anything at all. Also lining up the sound clips becomes critical, down to the very sample, so maybe it is not a feasible idea, in which case I want my time back that I spent typing this...

 

[Drag0n]

Using my Chaintech Av710 > Canare Starquad mini to mini > Shellbrook MaxiMoy > Gradp SR80.....

I might be imagining it, but the Right Wave version seems to have more echo and the Left Wave version seems like her lips are closer to my ear with less room ambience, but its so slight and i could be imagining it....but listen for that exact artifact yourself.

Even if there is a difference though, its not worth the money to change cables. Niether is better, just possibly different.

A well made $10 Volex cable would be fine in this case then.

Ill have to listen again to be sure of what i heard, but if there is a difference, it isnt much at all.

Maybe the difference would be more prominant on a high powered stereo amp though, being it will draw some serious current.

 

[infinitesymphony]

If we didn't have to worry about the issue of time-alignment, we could cancel out whatever was alike between the two files, leaving only the differences...

Just looking at frequency spectrum vs. volume, it appears that the "Left" version is between 0.01-0.02 dB louder, but that might be because I don't have them perfectly time-aligned. Either way, the waveforms are extremely similar, even near the sample level. They're not identical, but they're close enough that a second playthrough with the same power cord might have yielded the same differences.

Thank you for putting together this test, SamNOISE. Admittedly, you've put much more effort and consideration into your wall power than most of us have. Perhaps some of the positive effects of a filtering or shielded power cord won't be noticeable if the incoming power is already good? At least, that's what a manufacturer might ask, especially if they include ferrous materials in their power cables.

 

[nick_charles]

I tried a small expt myself. I took the analog output from my Entech DAC and used it as the input to an Edirol external USB soundcard/DAC. I then ran this into my Toshiba laptop (Core 2 Duo) 1.5GB ram and recorded the same track sample 3 times. Since my Edirol has a pretty good SNR it was quite easy to recognise where the track started and I was able to align the samples and trim them all to exactly 1:00:000000, (give or take 0.000001s since audacity has finite limits). I then ran a spectrum analyser on all three tracks from 86 hz to 21963.87 in 255 steps. I might change the granularity and try again but it will do for now. I then used Excel to calculate the differences at each frequency for the first 23.8 seconds. The results were as follows

Diff-----------1 vs 2--------------1 vs 3------------- 2 vs 3

ave*****-0.00900618 *****-0.013965263 ******-0.004959082
max******0.173462********0.041366 *********0.102386
min******-0.168647*******-0.195579*********-0.281968


So there were still differences - though quite small between the 3 trials that *should* have been identical. The 0.17db and -0.19db differences look impressive but these were at 21447 and 21533 where the energy levels hovered around -107db.

EDIT
-----
Bother ! I just checked again and 1 and 2 are 0.000025 out of alignment - I will start again.

 

[Sovkiller]

Just as a double check, try to measure ten times the same track, to see if the curves are all alike...to me those differences observed could be more due to the tolerance of the instruments...

 

[markl]

I'm sorry, but IMO, this is the most ridiculous "test" of a cable I've ever read, I almost fell out of my chair laughing.

I can't understand what the OP thought he was measuring.

What exactly were you expecting the *power cord* to do to the individual digital bits encoded on the CD you were copying to your computer? It can't turn an AC/DC track into a Barry Manilow tune... You will get the same digital bits out as you put in.

What you have done here is analogous to filming a person tasting a glass of wine A and glass of wine B, standing back, looking at the playback and asking other people to prove that they can tell the difference between the two glasses of wine that the person in the video is drinking.


EDIT: adjusted the tone controls on my post to mediate some of the sarcasm.

 

[vcoheda]

power cables for filtration. interconnects for tone adjustment.

it's that simple.

 

[Sovkiller]

Here we go again....guys do you have any better suggestion for any other experiment, to prove that cables make a difference, other than your ears that will be really good for you, but for nobody else???

 

[nick_charles]

Quote:

Originally Posted by markl /img/forum/go_quote.gif This is the most ridiculous "test" of a cable I've ever read, I almost fell out of my chair laughing. I can't even believe the OP is serious about this. What exactly, pray tell, were you expecting the *power cord* to do to the individual digital bits encoded on the CD you were copying to your computer? Turn an AC/DC track into a Barry Manilow tune? What you have done here is analogous to filming a person tasting glass of wine A and glass of wine B, standing back, looking at the playback and demanding other people prove that they can tell the difference between the two glasses of wine that the person in the video is drinking. Bravo!

If power cables can make an audible difference then we should be able to detect some differences in the audio output, yes ?.

So we can either ask for listening experiences or we can do some measurements. In this case the op has posted two samples recorded using two different cables for us to listen to and examine at our leisure.

If the cables make a difference then the sound output of the playback device should be different, yes ?.

So far so good ?

Now we cannot experience the OP's personal listening experience so the OP recaptures the analog outputs via a digitization process. So we have the analog streams re-digitized and in that form we can mess around with it, do measurements on it, listen to them ourselves and so on.

We have to take it a bit on faith that the digitization process is a "near" perfect capture of the analog waveform and that it operates consistently. However with a decent band-limited capture device and or capture software the capture to 16/44.1 should be as good as we need. We also have to take it a bit on faith that the DAC behaves consistently in the first place.

If we can accept these assumptions then the digital captures should be sufficient to reveal any wave form differences between the two samples.

Now if we reject the assumption of the consistency of the DAC and ADC then we have a much bigger problem than changing cables since we can never know what differences can be attributed to normal variations and in this case no sensible comparison is possible, but in that case we can posit with some legitimacy that the cables themselves may behave inconsistently and we could never ever know when the do, if that is the case then no listening tests will ever be meaningful due to the possibility of random variation and we can all happily buy kettle leads.

 

[markl]

Quote:

Here we go again....guys do you have any better suggestion for any other experiment, to prove that cables make a difference, other than your ears that will be really good for you, but for nobody else???

If he wanted to do something scientifically valid that could "solve" the problem, he would take a statistically significant sample size of true, acknowledged "golden ears" (like an army of Michael Fremers and such), use *their* systems that they know like the back of the their hand, and then conduct your double blind test by swapping out *their* power cord of choice (the sound of which they know like the back of their hand), and swap it out with a cheap stock cord. Then report your results. That would be a good start. But this test?...

nick_charles, I wish I had more time to play today, but I am confident if people just *think* about this experiment for a minute or two, they will see that they are not measuring anything.

You guys agree a digital bit is a digital bit, yes? He's transferred the *exact same information* twice (albeit from different sources), and has ended up with (guess what) two identical copies of the same data! How on earth could they sound different?