The link to that thread is wierd... Here is the link straight to the Audio Asylum section about it: http://www.AudioAsylum.com/audio/dbt.html
Basically, DBT stands for Double Blind Testing. A way to do this would be to have a switch box that compares two components. Press the (A) button to select the first component, press the (B) button to select the second component, and press the (X) button to randomly select either A or B. You could listen to both, and then try the random button, and see if you can guess which one has been selected. Using that method is called ABX (named for the three buttons).
This all sounds well and good, I mean, its good to test things, double blind testing can be very effective and legit. So why make certain areas a 'No DBT/ABX Zone'? Basically, the problem is that Double Blind Testing is INCREDIBLY DIFFICULT TO DO CORRECTLY!! Not like 'kind of difficult', but INCREDIBLY DIFFICULT. There are people who go to school for 10 years just studying how to properly give this sort of test. One of the biggest problems that prevents us from doing any DBT or ABX testing is the design of the switchbox. How do you build a switch box that lets you do instant switching, but that doesn't affect the sound AT ALL? To test cables, you would need something that isn't active OR passive. If it was electrically connected, then it would garble the test by changing the auditory signature. Having someone switch the cables manually is the only way, BUT, that way, it takes too long for your auditory memory, and you can see what they are doing, which changes your preceptions (don't try to claim that it doesn't! We are all human beings, and are prone to bias, one way or the other). The only thing I've been able to think of is a robotic system who's entire control and motor system is on an independent power source. Super high precision griping systems would replicate a human grip on the cable, but could rapidly remove one cable, and plug in a second set. The switch would have to take less than 2 seconds. Then the first cable would have to be moved out of the way, and the robot would have to let go of the newly plugged in cable, move back, and then shut down. This would have to be done to prevent any effect of having a metal hand gripping the cable, and to prevent any electromagnetic interferece from a robot affecting the sound. You start to see how this gets incredibly complex. I think maybe NASA could build a robot that does that.. But even then, it would be hard to make it so that Button A and Button B's results would be identical IN EVERY WAY to each other except the cable, and that each position would be identical to a system that had only that cable, and no other cables. For a double blind test to work, ESPECIALLY with subtle things like cables, you need to control for EVERYTHING for it to be statistically valid. You might say "oh, if i make a good switchbox, and use quality parts to do electrical switching, then it'll be fine" and then someone can't tell the difference between two cables, you might laugh triumphantly and say, "See? I've proved that they are the same!" But it wasn't scientific, because you didn't control your experiment! If you tried to pull some crap like that at a research institution, they'd laugh you right out. Or at least look at you disapprovingly.
So basically, arguments about Double Blind Testing and ABX testing are doomed to go nowhere
, and will always result in flame wars and unhappiness. It is NOT a cop-out for people who don't want to admit that their cables don't make any difference. It is based in the science of double blind testing, and its inherent difficulties.
When some professional academic institution develops a complete, perfectly controlled mechanism for doing ABX and double blind testing with audio components that takes into account ALL possible control aspects, then I'm sure Jude will lift the DBT ban so they can tell us about it. But until that happens, its best to just let people come to their own conclusions. I can use little tests to convince myself, but I can't go boasting that i've proved
anything until I do a REAL DBT test, with lots of subjects.
People try to 'prove' that certain cables are better than others, or they try to 'prove' that cables don't make a difference, but none of that is true proof, its all just hearsay, conjecture, and unscientific testing. You can give your opinions, either that you didn't notice a difference, or that you did. No one can tell you conclusively that you are 'right' or 'wrong'. I can shout PLACEBO at you all day long for claiming that a 500$ cable was better than a 20$ cable, but i'm just blowing wind because I can't offer any proof besides what I happened to notice (that is assuming, of course, that I actually listened to the expensive cable
). Likewise, I can call you "Mr. Tin Ears" till i'm blue in the face because you didn't notice a difference between the radio shack cable and the 1000$ wonder-cable, but I can't prove jack, I can only offer my own experience, once again assuming that I actually listened to them both myself!
Anyway, hope that clears things up. Things like this are very touchy in the audio world, and other worlds too. In scientific communities, DBT and ABX testing about other things is regarded VERY carefully... If you are doing tests like that, you are expected to document EVERYTHING, and to analyze the effect that EVERY variable has on the situation. Very difficult. But the scientific community realizes that those things have to be done to really get any true value out of a DBT test. What we are looking at here is a very real application of the Heisenberg Uncertainty principle, where the act of measuring something changes the outcome in an unpredictable way
. This isn't a limit of technology, its a fact of the universe's structrure (if you want, we can talk more about Physics and its implications on the world, and our daily lives).
I'm open to more scientific investigation into the properties of audio equipment, but people must realize the depth and complexity. A sound card and a cheap osilloscope are not enough for me to 'prove' a cable is the same as another cable. You aren't controlling the experiment. Its not scientific.
Now, anyway, to wrap up this little rant/explanation, I'd like to note that I'm still agnostic when it comes to cables. The engineer in me says 'bah, they are the same' and yet the audiophile in me says 'no, there is a difference, its just subtle.' I've heard differences, but i'm not sure if its placebo or not. I don't think someone who says their 500$ cable sounds way better than their 20$ cable is full of crap, but I also don't think that someone who feels that its placebo should be laughed out of the room. I think we should be open minded, listen to people's intelligent reviews and experiences, and then try it for ourselves. Then we can decide what we want, and what makes us happy.
Group Hug! Cable naysayers, and yaysayers alike!