[jules]

Lightfire, would you like to hone your suggested test a little?

As Marbles has pointed out, 100% correct is not required and in fact if you claim to have done such tests and achieved 100% accuracy in the results, I am very skeptical.

I see no reason why the listener should be told that the cable is being changed from "cable A" to "cable B". One useful testing procedure is to "change" cable A to cable A again to see if the listener "perceives" a difference. Telling the listener which cable they are listening to  [A, B or C] increases the probability of guessing correctly. Put another way, the less you tell the listener, the better the test.

You suggest that 15 (between three cables at random?) tests [or more] should do the trick but in reality what you might get from this is a result like .. 9 correct and 6 wrong. From this, you would need to decide what proportion correct could occur by guessing [which is not 50% in such a small sample] and beyond that, how significant your results are. This is why I earlier suggested that 50 tests would be the sort of number needed to get a statistically meaningful result.

Now, if you have your listener hearing the same track from the same CD 50 times other factors come into play ... namely, they get bored with the sound and hence their judgment is altered.

So ... any advance on the first test?

jules

[mfsoa]

Years ago one of the Steroephile/AbSound reviewers (I don't recall) participated in some sort of Analog-vs.-Digital AB/X test at an electronics show, feeling confident he could pass the test. He nailed it, 7 right out of 7, having no problem hearing the differences.

And then was told that this was NOT considered a positive result, since statistically, there was some probability that random guesses would also give a 7 for 7!

[Occam]

JohninCR,

I guess the attack part was my frustration with your reference to powercords. Yes, I realize you were not the one who introduced cords into this discussion. Screw powercords. Inevitably, when there is a discussion of powerconditioning, someone just has to bring powercords into the picture. (the same way that if there is a discussion of whatever tweak, someone allways makes reference to those $400 wooden knobs )

I certainly don't have any issues with your subjective investigations into OB geometry. We work with the tools available to us, and we both realize our own ears are valuable tools in our investigations. And as my interest is DIY powerconditioning, rigorous objective measurements as well as controlled subjective experiments are easier than investigations into other areas of audio reproduction.

But unlike you, the preponderance of subjectivists are armchair critics. They opine that nothing is valid if not vetted by their own rigorous standards, like LightFire's insistence on 100% accuracy in identification. In other words, they don't have a clue.  They build these torturous 'thought experiments' that although convenient, are not clouded by actual empirical investigation, and yield definitive conclusions. Often wrong, but definitive nevertheless.

I realize that most empirical experiments involving listener's subjective evaluations are flawed, including my own. It a no win scenario.

Regards,
Paul

[LightFire]

I would like to apologize to Occam to have introduced power cords in a power purifiers discussion. It was a momentary lapse of reason.

Lightfire, would you like to hone your suggested test a little?

I see no reason why the listener should be told that the cable is being changed from "cable A" to "cable B". . .

Jules. Here are some more reliable links to ABX info:


http://en.wikipedia.org/wiki/Double-blind

http://en.wikipedia.org/wiki/High_fidelity#Ascertaining_high_fidelity:_double-blind_tests

http://en.wikipedia.org/wiki/Codec_listening_test

[miklorsmith]

Initial post:

As an ex manufacturer I can tell you some of the experiences I had.
Audiophiles come in two different groups as far as this is concerned. The first group appreciates things like RFI/EMI filters at the AC input and regulated power supplies in their power amps.
The second group would rather pay less for the individual unit and use assorted power conditioners and expensive cables.
            d.b.

LF - maybe you're not aware how useless ABX debates are or how they kill threads.  Can we please try to stay on-topic?  Anybody wanting to start another ABX discussion somewhere like Fight Club, great, do it.  Or better yet, start one on AH and find legions of kindred listeners.

[Dan Banquer]

Initial post:

As an ex manufacturer I can tell you some of the experiences I had.
Audiophiles come in two different groups as far as this is concerned. The first group appreciates things like RFI/EMI filters at the AC input and regulated power supplies in their power amps.
The second group would rather pay less for the individual unit and use assorted power conditioners and expensive cables.
            d.b.

LF - maybe you're not aware how useless ABX debates are or how they kill threads.  Can we please try to stay on-topic?  Anybody wanting to start another ABX discussion somewhere like Fight Club, great, do it.  Or better yet, start one on AH and find legions of kindred listeners.

Speaking of power cords; does anyone know of manufacturer whose web site actually has some spec's on their power cords and that include attenuation of RF? A frequency response of the cord or something that says that it has x amount of attenuation at a given frequency would be helpful.
I hope this is not an unreasonable question to ask.
                                    d.b.

[JohnR]

 

 

[Dan Banquer]

 

 
d.b.

[Carlman]

I agree, this thread's had it.  If anyone is genuinely interested in discussing this kind of thing, pick some part of it and start a new thread.... If you mainly just want to argue about it, start it in Fight Club.