Power Cord Abx Test

[Mudcat]

A rather long read, but the results should not surprise anyone.




http://www.hometheaterhifi.com/volume_11_4/feature-article-blind-test-power-cords-12-2004.html

 

[Audioholics]

Hmm... So basically Jason just admitted that his power cord reviews were really full of... uh, misconceptions.

"As soon as the Black Mambas had settled in, I discovered that instruments had grown in size, weight, dynamics and believability. Everyone who had previously heard my system was immediately impressed by the differences. Everything sounded more solid, three dimensional and “real.” This transformation was most noticeable on orchestral music, where instruments sounded larger, fuller, rounder, and more convincing."

It's nice that they went through the trouble to do that ABX test, but I suspect most of us could have saved them a lot of hassle. For someone who noticed such significant differences it's comical to see him score a rating that basically says he can't tell the difference one bit.

 

[jneutron]

Hmm... So basically Jason just admitted that his power cord reviews were really full of... uh, misconceptions.

It's nice that they went through the trouble to do that ABX test, but I suspect most of us could have saved them a lot of hassle. For someone who noticed such significant differences it's comical to see him score a rating that basically says he can't tell the difference one bit.

I beg to differ. I did not consider it comical...

I find it flat out admirable that he would write up these results, which are in direct contradiction with previous statements. He has "nads".

Without knowing the man, my respect for him has been raised somewhat.

Cheers, John

 

[Swerd]

First of all, I want to congratulate anyone who does a blind listening test, regardless of how well the study was done, and regardless of what the results were. It is a lot of hard work. It is far better to do the work and discuss the meaning of the results than to argue endlessly without any test results or to imagine reasons why you shouldn't perform such a test.

I also want to comment on a falsehood (IMO) that is often repeated about blind studies. About midway the article says:

It has often been said that the only way to resolve this apparent dichotomy is to use carefully controlled blind listening tests, where the listener does not know what he or she is listening to. In this manner, imaginary differences should fall away, leaving real differences that can then be correlated with objective measurements. Unfortunately, as you will have noted, for example, from David Clark's infamous blind amplifier test in Stereo Review, it seems that with such blind listening tests, all perceived subjective differences between amplifiers (apart from those due to level, absolute polarity, and amplitude-response differences) fall away. The conclusion then drawn by some observers is that, indeed, once above a certain performance threshold, amplifiers do sound alike.

But when you have taken part in a number of these blind tests and experienced how two amplifiers you know from personal experience to sound extremely different can still fail to be identified under blind conditions, then perhaps an alternative hypothesis is called for: that the very procedure of a blind listening test can conceal small but real subjective differences. Having taken part in quite a number of such blind tests, I have become convinced of the truth in this hypothesis. Over 10 years ago, for example, I failed to distinguish a Quad 405 from a Naim NAP250 or a TVA tube amplifier in such a blind test organized by Martin Colloms. Convinced by these results of the validity in the Consumer Reports philosophy, I consequently sold my exotic and expensive Lecson power amplifier with which I had been very happy and bought a much cheaper Quad 405—the biggest mistake of my audiophile career!

The phrase in bold - the very procedure of a blind listening test can conceal small but real subjective differences - is often repeated as a reason why blind tests are not good. I always get bugged when I hear this. It is only one alternative hypothesis and there is no evidence for it or against it. Another equally possible alternative is that previous perceptions obtained from prior sighted listening experiences were affected by knowledge of which gear or cable were used.

It is itself a testable question. Develop a series of small but genuinely audible differences and test how many listeners can reliably hear them or some of them under blind conditions. That would answer the question of what is the threshold between small but audible differences that can be heard and those that are indeed masked by blind listening tests. To my knowledge, no one has ever tried to do this. But that never stopped the numerous speculations on how that might affect the results.

 

[MDS]

I agree totally Swerd. The bold passage you highlighted is not the only instance of fallacious reasoning. If you go to the Secrets site, you can read the thread that introduced the idea of the test before it was done.

 

[Richard Black]

<<I beg to differ. I did not consider it comical...

I find it flat out admirable that he would write up these results, which are in direct contradiction with previous statements. He has "nads".>>

Absolutely. Good on him for doing it and having the cojones to report it as it was.

 

[Audioholics]

I'll eat some humble pie and give him kudos for that as well. It says a lot about one's character.

 

[Swerd]

After a more thorough reading of this excessively long article, I noticed these other points. They are worth some attention:

Test participants were asked to rate themselves as to how much of an audiophile they considered themselves to be. The scale was 1 to 5 where 1 = “I’m not an audiophile at all” and 5 = “I’m a hardcore tweak.” (“Tweak” is the word Manny chose; I would not have used such terminology, which I find belittling in this context). The self-proclaimed hardcore audiophiles got 48% correct; the rest got 50% correct. Again, no significant differences based on whether or not a listener felt he was an audiophile or not.

Prior audiophile attitudes did not matter.

Those above the median age of 50 scored 43% as a group; those 50 and younger scored 53% as a group. Those who frequently attend concerts of un-amplified music scored 44%, those who don’t scored 50%. Those who play a musical instrument scored 47%, those who don’t 50%. The 9 out of 15 participants who have invested in after-market power cords scored 48%.

Age, concert-going experience, playing a musical instrument, and having purchased after-market power cords did not matter.

Twelve of the 15 participants gave themselves a 3 or better on the 1 to 5 scale of degree of audiophile dedication. Half of the listeners gave themselves a 3 or better regarding their belief that they could hear difference between power cords. Those who rated themselves above the median for their perceived ability to discern differences between power cords scored 49%, the same as those who rated themselves below the median.

Prior beliefs in the positive value of audiophile tweeks did not matter.

Those who on the post-test survey felt most strongly that they had heard differences between cords during the test did not perform better than those who rated their abilities at or below the median. Those who thought they did best scored 45%, while those who thought they did so-so or poorly scored 50%.

And finally, belief by listeners that they were indeed hearing differences between power cords during the test, again made no difference.

While it is true that I am not surprised by these results, this test provides a pretty good demonstration that a number of arguments, often made by audio subjectivists who claim they can hear differences in cables, cannot be verified by blind listening tests.