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Topic: Power cords blind test (Read 11898 times) previous topic - next topic
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Power cords blind test

In "Secrets of Home Theatre and High Fidelity", Jason Victor Serinus has published a blind test between high-end audiophile power cable and standard power cable.

http://www.hometheaterhifi.com/volume_11_4...ds-12-2004.html

It is interesting to note that though all participants failed the test, all of them thought that they could have heard the difference. On a scale from 1 to 5, half of them claimed that they can hear the sound of a power cable with an estimation of their ability equal or superior to 3. Some of them define themselves as "hardcore audiophiles". Some of them regularly attend acoustic concerts, thus are used to natural sound. Some of them play a music instrument.
A funny comment from one of them : "SPL should have been matched. In the most basic sense the test was successful, but the difference in volume made the cable identifiable". He didn't perform better than the others.

Power cords blind test

Reply #1 –
A very interesting read. I sensed an audiophile bias through the whole article, but at least they admit that ABX testing proved that they could not tell the difference.

Power cords blind test

Reply #2 –
What a wonderful article!

* 14 out or 15 felt the test procedure was reasonable

* Half of the listeners felt they heard a difference

> The results were 73/149 correct - i.e. 50% correct: pure chance.


What's more, when asked after the test, the listeners who were certain they heard a difference during the test scored 45% correct!


This is something new - I've seen other tests where listeners knew they'd failed - they proceeded to attack ABX methodology. Yet in this test, the listeners were asked how they thought they'd done before being told their results. They honestly believed they'd heard a difference and had written it down - they didn't say "the difference is too subtle" or "this test hides the difference" - they said they did hear a difference.

But they clearly didn't, because they couldn't tell one cable from the other more than 50% of the time! As often as not, they would have got better results from flipping a coin!

This shows all sighted listening tests are junk. Simple as that.

When will they ever learn?

Cheers,
David.

Power cords blind test

Reply #3 –
It's a little subtler than that. It's theoretically possible that somebody did in fact tell a difference while everybody else didn't, but his "more positive" results got lost in the noise. But those percentage scores by listener sure seem bell curve shaped to me, and since nobody scored better than 60%.... I suspect this could be diced around a bit to yield an equivalence result with a low but meaningful significance. Also 10 responses per listener is rather low, and the cable switching time was very long, so those things do affect the power of this test.

Remember kids, nonrejectance of the null hypothesis does not mean equivalence.

Power cords blind test

Reply #4 –
A very interesting read indeed.  There are some admitted shortcomings to the test, but it sure it interesting that the particiapants scored almost exactly 50%.

Yes, sighted listening tests are junk.  I admire the people who conducted this test to have the courage to set it up with attempts to make it blind, while many publications use their pages to peddle overpriced, uesless products without a scrap of science behind them.

Power cords blind test

Reply #5 –
A friend of mine suggested that, for an encore, they A/B/X test with different power sources - Hydro vs. Nuclear vs. Coal vs. Wind. This may require a more elaborate setup...
 

Power cords blind test

Reply #6 –
Quote
It's a little subtler than that. It's theoretically possible that somebody did in fact tell a difference while everybody else didn't, but his "more positive" results got lost in the noise. But those percentage scores by listener sure seem bell curve shaped to me, and since nobody scored better than 60%.... I suspect this could be diced around a bit to yield an equivalence result with a low but meaningful significance. Also 10 responses per listener is rather low, and the cable switching time was very long, so those things do affect the power of this test.

Remember kids, nonrejectance of the null hypothesis does not mean equivalence.
[a href="index.php?act=findpost&pid=259407"][{POST_SNAPBACK}][/a]


It's true that it would be better to have more tests per listener, and then (if one listener appears to hear something) re-test that listener.

But what I was really picking up on were the people who honestly believed they could hear a differences (and presumably believed they were accurately reporting that difference) but who scored ~50%.

OK, that doesn't "prove that they didn't hear a difference", but it does prove that they didn't hear the difference that they believed they heard.


Here is a daft example for you: If I look at ten pieces of paper, and say "OK, that one is red, that one is blue, that one is blue, that one is red, that one is blue" etc etc honestly believing and convinced of what I'm saying - but then it turns out I've only got 50% right - what are you going to conclude? Probably than I'm red/blue colour blind! However, more importantly you'd conclude that (for some strange reason) I'm imagining differences that I am not actually perceiving, because most normal people would score 100%, and most colour blind people would say "I can't tell a difference" - what you've uncovered here is a third type of person - a person who claims to perceive a difference, but doesn't.

Then this person defines themselves with a helpful label: "audiophile".

I rest my case.

Cheers,
David.

(In full knowledge that some "audiophiles" know exactly what they're doing and hearing)

P.S. What is more, anyone who has taken an ABX test will know that you can pass it when detecting a difference which you find is on the very edge of your perception: you would never say you could confidently hear a difference, and yet you can just detect something and score a very significant score, e.g. 15/16. Whereas here we have people saying they can definitely hear and report a difference, and they score 5/10! Then people have the cheek to say that ABX is insensitive!

Power cords blind test

Reply #7 –
In my audiophile days, i was ABXing several different power cables, and i never got the impression that there was actually some true gain form using either of them. Sometimes i happened to have the impression there are subtle differences, but i was realistic enough to not go any further into this, and decided to invest the money ( and some of them were HELL expensice  ) into those components which are the weakest part of most stereo systems instead .... the speakers  .......

Christian

Power cords blind test

Reply #8 –
Quote
A friend of mine suggested that, for an encore, they A/B/X test with different power sources - Hydro vs. Nuclear vs. Coal vs. Wind. This may require a more elaborate setup...
[a href="index.php?act=findpost&pid=259573"][{POST_SNAPBACK}][/a]


let's do it!

i reckon hydro will sound better, because it's more natural.  coal will make the sound coarser, i think, and nuclear will give it an "overcooked" sound.  i think wind powered music would lack presence.

(is that audiophile sounding enough?)

better yet, seeing as we all know audiophile is basically a form of elitism, lets do a test of the same system in different physical locations - will Melbourne sound better than Sydney? (i've always suspected this to be the case )  does classical sound better in Berlin?

i'm sure the Earth's magnetic field has a huge effect on playback, though even in a sheilded room, i'm sure there's other factors that affect sound... perhaps neutrino activity can cause a perceptible change?  if that's the case, then i'm all for audiophiles setting their systems up 4 kilometres underground, in granite.

then there's exotic particles like tachyons... and what about gravity waves?  nobody's detected them at all yet, but i'm sure a golden eared audiophile can hear their effect.

Power cords blind test

Reply #9 –
Quote
Quote
A friend of mine suggested that, for an encore, they A/B/X test with different power sources - Hydro vs. Nuclear vs. Coal vs. Wind. This may require a more elaborate setup...
[a href="index.php?act=findpost&pid=259573"][{POST_SNAPBACK}][/a]


let's do it!

i reckon hydro will sound better, because it's more natural.  coal will make the sound coarser, i think, and nuclear will give it an "overcooked" sound.  i think wind powered music would lack presence.

(is that audiophile sounding enough?)

better yet, seeing as we all know audiophile is basically a form of elitism, lets do a test of the same system in different physical locations - will Melbourne sound better than Sydney? (i've always suspected this to be the case )  does classical sound better in Berlin?

i'm sure the Earth's magnetic field has a huge effect on playback, though even in a sheilded room, i'm sure there's other factors that affect sound... perhaps neutrino activity can cause a perceptible change?  if that's the case, then i'm all for audiophiles setting their systems up 4 kilometres underground, in granite.

then there's exotic particles like tachyons... and what about gravity waves?  nobody's detected them at all yet, but i'm sure a golden eared audiophile can hear their effect.
[a href="index.php?act=findpost&pid=259914"][{POST_SNAPBACK}][/a]

I'm afraid you have crossed the HA TOS #8  , could you provide some sample to support your claims   

Power cords blind test

Reply #10 –
Discussion about the test : http://hometheaterhifi.com/forum/showthrea...48&page=1&pp=10 (I chimed in around page 16).

MugFunky, it's too bad that the articles ( http://perso.planetis.com/pascal.tantin/HI...%20du%20son.htm ) and discussions ( http://www.homecinema-fr.com/forum/viewtopic.php?t=29760965 ) about Pierre Johannet's tweaks are in French. I'm sure you'd love them !

Power cords blind test

Reply #11 –
It was interesting how the author kept referring to how "well" the participants did, as if the test was of the participants' hearing rather than the power cable performance. Even with that in mind, thinking of the results as being on a scale of good to bad is still the wrong mindset for good science; one must desire the result, whatever it is. All results are good, as contrasted with an inconclusive experiment.

Power cords blind test

Reply #12 –
Some day I'd like to perform a blind test without ever changing a cable, and wait for the reviews on all the differences to come in

Power cords blind test

Reply #14 –
Hi folks, just had a quick read through the article and wasn't surprised about the results.

Quote
In my audiophile days, i was ABXing several different power cables, and i never got the impression that there was actually some true gain form using either of them. Sometimes i happened to have the impression there are subtle differences, but i was realistic enough to not go any further into this, and decided to invest the money ( and some of them were HELL expensice  ) into those components which are the weakest part of most stereo systems instead .... the speakers  .......

Christian
[a href="index.php?act=findpost&pid=259629"][{POST_SNAPBACK}][/a]


I agree to ChristianHJW about investing your money into the weakest part of a playback system, mainly the speakers.

I already had several discussions about this with mastering engineers at some reputable mastering studios.
The main argument not to worry much about power cords is that the wires from the wall outlet of your electrical installation in the house are just simple cheap solid copper wires. And these are quite some multiple tens of meters of them. So why should using an expensive power cable between the wall outlet and your stereo make things different? And all your good gear has serious mains filters and dc-power filters integrated. Buying heavy power cords is really a waste of money, invest it into your gear and you won't regret that.

Greets, Ivo

Power cords blind test

Reply #15 –
wait, don't you know that a good 'line conditioner' will CLEAN UP all that grunge the current gathered whilst travelling through all that dirty low-class copper??


Power cords blind test

Reply #16 –
That's why I got the local power company to lay gold lines all the way from my house to the substation. Do you have any idea what a gold wound 100MVA transformer costs? It's worth it for the sound quality, though.