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My cable test enterprise

post #1 of 438
Thread Starter 

measurements consolidated into one post !

 

 

Quote:

Originally Posted by nick_charles View Post

Cables arrived


All cables



Audioquest



Audioquest-unboxed


Blue jeans


Tartan (Belden)


Stocky


Monoprice


Audioquest-Blue-jeans-AR


Quote:

Originally Posted by nick_charles View Post

So the first order of business was to see how flat the response of each cable was.

First I generated a 40 second clip of white noise , I saved this as a Wav file and ran it through a spectrum analyser,
this is the reference point.

Then I burned the sample to CD and tested each of my CD players by playing it back and recording the analog
output to find the one most like the reference in shape and overall level. I settled on a Denon DCD910 analog
output which had the lowest deviation from the reference from 20 - 20K using stock cables.

Now I set about more critically measuring the response for the 4 cables I bought plus my own 77c specials.

To do this I played back the white noise sample and recorded it to my PC. To cater for random variations
I did each recording with each cable **10** times.

Each resulting wav file (70 of them, I tested the AQ cables aligned by the arrows and unaligned to test for the claimed directionality) was clipped to exactly 24.003628 seconds, each file is precisely
4.03 MB (4,234,284 bytes) all white noise. Due to careful editting ( the same protocol used for each file)
no wav file can differ from any other wav file in alignment by more than 1/1000th of a second.

Each file was then run through a spectrium analyser with 1024 sample points. Each spectrum was exported as a text file.

Then I started up Excel and I loaded each set of ten trials into a separate worksheet. This allowed me to see the Min, Max and Average levels for any frequency. Also it allowed me to see how much variation there was in any set of trials.

For instance the biggest difference between any two trials for any frequency with the Stock cables was 0.056db, the average difference between the max and min value for all frequencies for stock cables was 0.032 db.

Tartan cable 0.032 and 0.014
BlueJeans 0.047 and 0.016
AQ G-Snake Not Aligned 0.061 and 0.016
AQ G-Snake Aligned 0.038 and 0.013
AQ Sidewinder Not 0.050 and 0.014
AQ Sidewinder Aligned 0.044 and 0.014


Quote:

Originally Posted by nick_charles View Post

The way that the recording was set up meant that each recoding was always at a slightly lower absolute level than the reference. Thus the best cable by definition at any frequency would have the highest value or the lowest attenuation from the reference. This made life easy.

In no case did any cable boost any frequency above the reference level.

Each set of 10 trials for each cable was averaged and the results fed into the worksheet with the reference values.

The maximum difference found between any two cables at any frequency point was 0.029db. The average difference between the best and worst cable across all frequencies was 0.012db. Note that the identity of best and worst cable did differ between frequencies.


Quote:

Originally Posted by nick_charles View Post

Two of the cables I purchased are supposed to be directional. I recorded samples using the Audioquest G-Snake and Audioquest Sidewinder both correctly aligned and incorrectly aligned. I recorded 10 samples with each of the 4 combinations.

The G-Snake correctly aligned was in fact measurably different from the G-Snake incorrectly aligned. When I fed the results into SPSS the result was significant.

the maximum difference at any frequency was 0.022db and the average difference was 0.001db. For the Sidewinder the maximum difference was 0.011db and the average difference at all frequencies was 0.002db.


 

Quote:
Originally Posted by nick_charles View Post

Do any of these cables roll off any more than any others. I tested the differences in level between 1K and 20K, 2K and 20K, 3K and 20K, 4K and 20K, 5K and 20K, 6K and 20K, 7K and 20K, 8K and 20K, 9K and 20K, 10K and 20K, 11K and 20K, 12K and 20K, 13K and 20K, 14K and 20K , 15K and 20K and finally between 16K and 20K.

The maximum difference in roll-offs between any two cables for any two frequencies was 0.016db


Quote:

Originally Posted by nick_charles View Post

Stock(77c) vs Sidewinder ($60) , max diff 0.020db, ave difference 0.009 db
Stock(77c) vs G-Snake ($35) , max diff 0.013db, ave difference 0.003 db
Stock(77c) vs Blue Jeans($26.75), max diff 0.014db, ave difference 0.004 db
Stock(77c) vs Tartan ($5) , max diff 0.009db, ave difference 0.003 db

Tartan ($5) vs Sidewinder ($60) , max diff 0.014 , ave difference 0.006db
Tartan ($5) vs G-Snake ($35) , max diff 0.009 , ave difference 0.003db
Tartan ($5) vs BJC ($26.75) , max diff 0.007 , ave difference 0.002db

BJC($26.75) vs Sidewinder($60), max diff 0.011 , ave difference 0.005db
BJC($26.75) vs G-Snake ($35), max diff 0.012 , ave difference 0.004db

Sidewinder vs G-Snake max diff 0.018 , ave difference 0.009db


 

Quote:
Originally Posted by nick_charles View Post

I just loaded my dataset up into SPSS and ran a repeated measures ANOVA with cable type as a covariate and some ANOVAs between cables.

The results show that for these cables there was no significant effect on changing cable, no cable was significantly different from any other. Frequency also did not alter the result, no cable was significantly different at any frequency.

The other result was that there was much more variation between trials than between cables, this is entirely predictable as a cable is a passive device and and ADC is not, so my decision to average 10 trials was justified. Amusingly the repeated measures variation was significant. Remember this was a variation of no more than 0.056db between any two trials for any given cable at any frequency, but when you have 4600+ data points little differences become statistically significant.



 

Quote:
Originally Posted by nick_charles View Post

I just tested the Sidewinder vs the stock cable using a cymbal crash with lots of harmonics and transients.


Quote:

Originally Posted by nick_charles View Post

Stock and Sidewinder

Complex set of square waves from 10hz to 10000hz, maximum difference 0.027, average diference 0.0028


 

Quote:
Originally Posted by nick_charles View Post

New test of Sidewinder vs Stock cable with cymbal crash
-------------------------------------------------------

Max difference 0.102340db average difference 0.003539db

Average overall signal
Stock------------ Sidey ------------ difference
-37.743888 ******-37.742651 ****-0.001237







This graph shows the stock cable with the sidewinder dropped by 20db so you can see the patterns




For the Anoraks - the distribution of differences against frequency




And finally difference vs signal level


 

Quote:
Originally Posted by nick_charles View Post

With many thanks to Maxvla I have a 0.5m Zu Oxyfuel on loan for testing. I ran the cymbals test and compared the results against the stock cable.

The max variation was 0.08db at 129hz and -54db, the average difference is 0.001408db.


 

Quote:
Originally Posted by nick_charles View Post

These were done using a five second sample of digital silence and recorded back via the ADC. I ran the tests ( 10 trials) for both stocky and the Zu Oxyfuel.

Average Noise levels Stock -95.7975db.........Zu Oxyfuel -95.8598db

This is quite close to the theoretical noise levels for 16 bit systems



Low frequency noise pattern
---------------------------



I also did a few tests on my $2.11 Monoprice and the $60 Sidewinder. Interestingly each cable has a distinct noise pattern with specific low level spikes at different frequencies.

To place these noise figures in context, here is the noise juxtaposed against the cymbals crash.




In absolute terms the stock cable is the worst for noise with three low frequency spikes between -78 and -76db , how relevant this would be for normal music listening is arguable. Early tests suggest that the Monoprice is as good as the most expensive cables for noise, but I will need to run 10 trials.


Quote:

Originally Posted by nick_charles View Post

This text is between a DH labs BL-1 Series II Silver Plated Copper cable and the solid copper Sidewinder with the cymbals sample.

Maximum difference is at 19488hz where the difference is -75.3254db to
-75.3695db i.e a difference of 0.0441db, average difference from 20 to 20K is 0.0014 db. See graph below



 

Quote:
Originally Posted by nick_charles View Post

Noise pattern fro DH Labs cable - nothing unusual here, low levels of background noise at an average of -95.63db and a few spikes at ~ -86db

 

Quote:
Originally Posted by nick_charles View Post

White Noise tests 20 - 20K
-------------------------
Maximum difference at any frequency = -0.00436 db , the Monoprice cable has less attenuation at all frequencies, the average difference = - 0.00266 db.

No graph posted, no point , impossible to see the deviations.


 

Quote:
Originally Posted by nick_charles View Post

For these tests I made a slight change to my protocol I used a 16K FFT analysis which translates to 7K sample points. Since I have all the original wav files I may redo them with a smaller FFT later if it is a bust.

Noise differences ranged from
Freq (Hz)SilverCopperdiff
1418-101.0146-92.8366-8.1781
1421-100.8319-95.2206-5.6112
1416-100.7780-95.2324-5.5456
541-99.8670-96.9008-2.9662
15111-97.3906-95.1398-2.2508
538-99.8972-97.7621-2.1351

to

Freq (Hz)SilverCopperdiff
721-79.8842-95.098515.2143
301-80.4885-95.816915.3284
299-79.8153-95.577015.7617
719-79.4283-95.246215.8179
121-65.8202-82.408316.5881
600-79.7158-96.373216.6574
118-66.7071-83.371416.6642
363-80.7216-98.865118.1435
358-73.5922-99.016525.4243
361-70.9139-98.449627.5356


Silver Average Noise level = -97.8339 db
Copper Average Noise level = -99.5085 db
Average difference = 1.6746 db


 

Quote:
Originally Posted by nick_charles View Post

Averages
silvercopperdiff
-35.1717-35.19860.0269


Range of differences from

Freq (Hz)silvercopperdiff
10864-31.2361-31.1511-0.0850
12037-34.3904-34.3113-0.0791
19598-64.2617-64.1956-0.0661
17821-60.0233-59.9590-0.0643
18050-53.2547-53.2003-0.0544
19668-64.8693-64.8172-0.0521


to

Freq (Hz) silvercopperdiff

17870-58.5000-58.59830.0983
12029-32.1039-32.20500.1011
19679-68.4469-68.55140.1045
19663-66.2487-66.38070.1321
121-53.2967-53.58550.2888
118-55.8897-56.20280.3131





Differences vs frequency

 

Quote:
Originally Posted by nick_charles View Post

Average difference levels from 3hz to 20Khz

Silver copper diff
-12.2418-12.26050.0188


Range of differences
Freq(Hz)Silvercopperdiff
19237-12.7538-12.76280.0090
19902-13.4680-13.47800.0100
19862-13.2093-13.21950.0102
19657-13.5434-13.55390.0105

to
Freq(Hz)Silvercopperdiff
12880-12.7116-12.73470.0231
16422-13.0786-13.10170.0232
8454-12.6774-12.70070.0233
8064-11.8652-11.88850.0233
18594-13.4783-13.50170.0234
17286-13.2584-13.28180.0234
11666-13.2417-13.26540.0237
7580-11.4654-11.48910.0237
19113-13.3649-13.38870.0238
10933-12.7789-12.80300.0241

Differences vs frequency
-----------------------




Pattern of Frs against Frequency




 

Edited by nick_charles - 2/26/11 at 4:00pm
post #2 of 438
Thread Starter 
So the first order of business was to see how flat the response of each cable was.

First I generated a 40 second clip of white noise , I saved this as a Wav file and ran it through a spectrum analyser,
this is the reference point.

Then I burned the sample to CD and tested each of my CD players by playing it back and recording the analog
output to find the one most like the reference in shape and overall level. I settled on a Denon DCD910 analog
output which had the lowest deviation from the reference from 20 - 20K using stock cables.

Now I set about more critically measuring the response for the 4 cables I bought plus my own 77c specials.

To do this I played back the white noise sample and recorded it to my PC. To cater for random variations
I did each recording with each cable **10** times.

Each resulting wav file (70 of them, I tested the AQ cables aligned by the arrows and unaligned to test for the claimed directionality) was clipped to exactly 24.003628 seconds, each file is precisely
4.03 MB (4,234,284 bytes) all white noise. Due to careful editting ( the same protocol used for each file)
no wav file can differ from any other wav file in alignment by more than 1/1000th of a second.

Each file was then run through a spectrium analyser with 1024 sample points. Each spectrum was exported as a text file.

Then I started up Excel and I loaded each set of ten trials into a separate worksheet. This allowed me to see the Min, Max and Average levels for any frequency. Also it allowed me to see how much variation there was in any set of trials.

For instance the biggest difference between any two trials for any frequency with the Stock cables was 0.056db, the average difference between the max and min value for all frequencies for stock cables was 0.032 db.

Tartan cable 0.032 and 0.014
BlueJeans 0.047 and 0.016
AQ G-Snake Not Aligned 0.061 and 0.016
AQ G-Snake Aligned 0.038 and 0.013
AQ Sidewinder Not 0.050 and 0.014
AQ Sidewinder Aligned 0.044 and 0.014
post #3 of 438
Thread Starter 

Differences between cables part 1

The way that the recording was set up meant that each recoding was always at a slightly lower absolute level than the reference. Thus the best cable by definition at any frequency would have the highest value or the lowest attenuation from the reference. This made life easy.

In no case did any cable boost any frequency above the reference level.

Each set of 10 trials for each cable was averaged and the results fed into the worksheet with the reference values.

The maximum difference found between any two cables at any frequency point was 0.029db. The average difference between the best and worst cable across all frequencies was 0.012db. Note that the identity of best and worst cable did differ between frequencies.
post #4 of 438
Wow, very thorough so far. Excellent write-up! I can't wait to see more on this. I've been ordering Monoprice interconnects feeling a bit bad about not springing for more expensive ones. I think these tests might make me feel a bit better.
post #5 of 438
Interesting, I like the thoroughness. I've never heard any difference between IC's so I'll be interested to see just how big a difference there really is. I wonder what the audible threshold is.. I'm guessing .05 of a db is pretty much insignificant.
post #6 of 438
Thread Starter 

Can Audio cables be directional ?

Two of the cables I purchased are supposed to be directional. I recorded samples using the Audioquest G-Snake and Audioquest Sidewinder both correctly aligned and incorrectly aligned. I recorded 10 samples with each of the 4 combinations.

The G-Snake correctly aligned was in fact measurably different from the G-Snake incorrectly aligned. When I fed the results into SPSS the result was significant.

Before anyone gets excited the maximum difference at any frequency was 0.022db and the average difference was 0.001db. For the Sidewinder the maximum difference was 0.011db and the average difference at all frequencies was 0.002db.
post #7 of 438
Thread Starter 

Cable Roll-offs

Do any of these cables roll off any more than any others. I tested the differences in level between 1K and 20K, 2K and 20K, 3K and 20K, 4K and 20K, 5K and 20K, 6K and 20K, 7K and 20K, 8K and 20K, 9K and 20K, 10K and 20K, 11K and 20K, 12K and 20K, 13K and 20K, 14K and 20K , 15K and 20K and finally between 16K and 20K.

The maximum difference in roll-offs between any two cables for any two frequencies was 0.016db
post #8 of 438
Thread Starter 

Direct Comparisons

Stock(77c) vs Sidewinder ($60) , max diff 0.020db, ave difference 0.009 db
Stock(77c) vs G-Snake ($35) , max diff 0.013db, ave difference 0.003 db
Stock(77c) vs Blue Jeans($26.75), max diff 0.014db, ave difference 0.004 db
Stock(77c) vs Tartan ($5) , max diff 0.009db, ave difference 0.003 db

Tartan ($5) vs Sidewinder ($60) , max diff 0.014 , ave difference 0.006db
Tartan ($5) vs G-Snake ($35) , max diff 0.009 , ave difference 0.003db
Tartan ($5) vs BJC ($26.75) , max diff 0.007 , ave difference 0.002db

BJC($26.75) vs Sidewinder($60), max diff 0.011 , ave difference 0.005db
BJC($26.75) vs G-Snake ($35), max diff 0.012 , ave difference 0.004db

Sidewinder vs G-Snake max diff 0.018 , ave difference 0.009db
post #9 of 438
Thread Starter 

And the winner is.....

The differences are so small as to be utterly and totally meaningless.

Nevertheless in an absolute numerical sense, if you insist , the best cable was the Sidewinder ($60) which consistently had the lowest attenuation , and the worst cable was the G-Snake ($35) which consistently had the highest attenuation. But we are talking 100ths of a db here.

But all these cables behaved absolutely identically , none had anything which could even remotely be called a personality, none changed the signal more than any other in any material way.

Next step music recordings and listening tests...Spreadsheet available from

http://www.mediafire.com/download.php?nkmzxdnm2n3
post #10 of 438
Tartan for 5 bucks should be a contender just for the price.
post #11 of 438
Is frequency response the only factor you're measuring, and do you think that will tell you enough about how they sound?

Well done for doing the experiment by they way, good man, you deserve respect for that.
post #12 of 438
Nice job.
post #13 of 438
Great job, finally a measurable experiment on interconnects.
post #14 of 438
Thorough. Good testing procedures. Thanks for taking the time to do trial and for posting the results.
post #15 of 438
Good work. I'd love to see this test done on some seriously expensive ICs though. Personally I've never heard a cheap Audioquest IC that was worth bothering with, but at least it shows there IS a difference, even if a tiny and arguably insignificant one.
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