Testing the audible differences in mains cables.

[Wakefield Turntables]

Fantastic, I applaud this test. However, who did all the setting up and did any of the participants listen to your test gear on previous occasions. The only reason I ask is because this can add bias into an experiment. Firstly if any other your listeners have heard your system previously they will know its strengths and weaknesses and this could be viewed as them being able to judge its sonic characteristics. Secondly did the person who assembled the test kit have any idea of the cable brand? Again this is another possible area where bias could be introduced. Sorry to sound like this but I actually get paid to design experiments and assess the validity of the methodology. No methodology is perfect but yours is the best I have seen so far to test cables. There are loads of other areas which could have also added bias into your experiment but thats for another day. Well done mate

[PaulStewart]

Andy, the person who assembled the kit and set it up was my assistant, he knew which lead was which for the purposes of switching the leads over and noting the results. He had no idea of my expectations of the leads, nor did the other test subjects. Even if you take my observations and scores out of the results they are not a lot different. This was done on kit we use every day that is pretty revealing, it's for monitoring after all. Sometime next year, I would like to repeat this with a larger subject base and more time. I simply did it 'cos I had the kit to hand and a quiet day and it seemed a good idea

[lurcher]

Yep, but the point of a double blind is to remove any doubt about "He had no idea of my expectations of the leads". Also who selected the order in which the leads were used?

Again, not trying to be negative, but for a truly rigorous test these things matter.

[PaulStewart]

The leads were tested in no particular order and as I said Nick, this was done off the cuff but I feel the results are valid, as far as they go. Next year I'd like to do it bigger and better, I may approach one of the show organisers. I'd also like to test linear PSUs against wall warts 'cos preliminary results with an MCRU 12v supply against a Stax wall wart running my Stax energiser & cans show a marked improvement with the linear, too a number of people, again with the test done blind.

[lurcher]

The leads were tested in no particular order and as I said Nick, this was done off the cuff but I feel the results are valid, as far as they go.

Yep, any thing I can do to help just ask. May be good to get Andy's input if this overlaps what he does professionally.

[synsei]

In some ways the point scoring system is moot, the fact that your test subjects could detect a difference between the three cables goes a long way towards putting this debate to bed. I look forward to the larger test Paul, well done

[User211]

Well I've tried swapping mains cables a few times and can hear no difference, even with Nordost level foo.

Measure any change and I might be convinced.

I got curious about tube rolling changing the sound a while back, so I did some system FR tests using a mic and different 211 valves. Tube rolling effects overall system FR - and what's more I have the data to prove it! As much as 3DB variations were detected in some parts of the frequency range.

[Oldpinkman]

Just briefly (cos I've got man-flu) to add my appreciation to this effort. Both the rational and non-defensive attitude, the desire for a reliable methodology, and the service of "being the ears"

(That was more than "both" wasn't it? Told you I've got man-flu)

The "Being the ears" is the key. As I have noted many a time before, I or anyone else not persuaded yet by mains cables or burnin, can sit and listen and not hear till we're blue in the face, and it only serves to prove we have cloth ears. To carry the debate forward constructively needs someone who is both able to hear the difference, and prepared to avail us all of that ability by giving up their time to do so. So much appreciated.

As I noted to Mike privately, the problem is that even the best test may not nail this subject forever, and it is doomed as Marco foretells to re-emerge recurringly through time, as the last debate is forgotten and it kicks off anew. To maximise the prospect of a really useful "nailer" rather than just another interesting account of someone who has heard a difference means that "the ears" need to be deployed as effectively as possible - the methodology Andrew and others alude to.

Briefly (for me) I would suggest Paul's test was more elaborate than necessary for the purpose of "proving mains affects the sound" and seems, quite appropriately probably, better suited to mains cable product development, or evaluation of alternatives for the purpose of selecting the most appropriate to use. This doesn't spoil the test, but makes it harder to replicate. And to achieve the goal of "proving mains cables" it is going to need to be a test which is consistently repeatable - either by (at least some) others in "their labs" , or by demonstration by Paul and his team for observers satisfying themselves that the test procedures have no possible risk of contamination.

And it begs a lot of questions, which need to be addressed. Like "why can't some others hear these affects"? Is it only applicable to those speakers? That room? That local mains grid? Further testing would be simplest if it were possible to definitively identify an audiophile cable and a standard one, which were readily available, and which should readily be able to show the difference with specific readily available equipment it is attached to (say a Quad 405-2 amp, or the wall-wart for a Bushmaster, or whatever)

It would probably also be helpful if Paul could suggest what he thinks might be happening - ie how a mains cable might affect the sound of equipment. If we can theorise "how" it may be easier to identify good test peripherals.

If we can theorise "how" - we may be able to identify a relevant means of measurement to confirm, but unlike Justin I do not believe a measurement ESSENTIAL to providing a powerful confirmation. Just good (the very best) controlled test procedure.

Once again - congratulations to Paul for taking the initiative and volunteering his ears.

[PaulStewart]

As for theories, well very tentative at this time, looking at both the audophile cables, they scored very close to one another but I note they are both well screened for RFI and of good mechanical construction. All the kit used was fed from the edit suite's UPS which gives a very clean sine wave. So I think RFI may be playing a big part here. The Black Rhodium Cratos cables are constructed to reduce microphony, as this cable came out best overall this may also be a factor, but I suspect it is just better at handling RFI. As I said, needs more work and a bigger sample. The most telling thing thing was Raff and Dave the two editors I roped in to help on this did not know what part of the system they were comparing could have been interconnects or anything. They are both experienced A/V editors coming from the studio business and the BBC respectively, so I trust their observations as I trust mine. As to why some people can't hear this effect, unless it's a blind test, I still think reverse placebo effect has some merit

[User211]

If we can theorise "how" - we may be able to identify a relevant means of measurement to confirm, but unlike Justin I do not believe a measurement ESSENTIAL to providing a powerful confirmation. Just good (the very best) controlled test procedure.

Test kit is more sensitive than our ears. A lot more sensitive. Whilst there may be no change in frequency response, any change may be measurable elsewhere. If I was making the things, I'd make sure I had the evidence that they make some sort of measurable difference FOR THE BETTER. If I couldn't do so, I wouldn't make them.

However, a really large sample set indicating that the test kit is failing to measure the correct parameters i.e. there really is beyond any reasonable doubt people heard a difference, would be very interesting. For some Paul's test may be enough.

Is there really that much magic involved in pushing air around, though? Can there really be something we can't measure with such an activity? I doubt it.