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Originally Posted by milkweg /img/forum/go_quote.gif
You said you have good memory of one amp, well, for your information, it takes less than one minute for your memory to distil to the point that your memory is completely invalid as a comparative device. That's why they do scientific ABX testing.
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That's a misunderstanding. I don't have this amp anymore, but the comparison was of course made with all three amps in the house then. «In good memory» should just say that I liked it quite a bit then and remember well its sound compared to the others. Actually I don't use any of my speaker amps anymore since quite a while.
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| So all those pro audio people that failed the ABX test are disqualified from being valid test subjects or what? Or perhaps your testing methods are not valid testing methods at all. |
To me they absolutely are, more so than what I gather from typical DBT scenarios. I didn't mean to disqualify the above-mentioned test persons at all -- another misunderstanding --, I have not even thought of them during wording of my statement. In fact I feel a bit sorry for them; most likely most of them have heard a bunch of amps and think they all sounded different; some of them may feel quite a bit unsettled in their audio world view by the test result. And I think I could absolutely have been one of them.
I know of at least one Head-Fier who has been converted from a «cable believer» to a dye-hard cable skeptic -- disillusioned by the negative result of an absolved DBT. Now it isn't generally a bad thing to get unsettled in a personal conviction, let alone to be critical and skeptical. Personally I consider it just as important to be skeptical towards DBT and a general mistrust against the reliability of human perception. While I know that human perception is anything but perfect and 100% reliable, that doesn't mean you can't rely on your senses in the long run. Such a philosophy is downright misanthropic in my book. It represents a technocratic approach which is quite common these days (in extreme form on Hydrogenaudio -- although it does make some sense there) -- some sort of backlash to new age and neo-mysticism. If it were true, you couldn't even ride a bicycle. On the other hand, your senses aren't completely reliable -- that's why it's always possible to cause an accident.
In other words: It's easy to fool yourself in a given moment, but in the long run you won't be satisfied with the sound of amp A just because it has cost more or looks prettier, although in fact it sounds the same as amp B which has been cheaper. And you wouldn't get persistent results by comparing them.
As to DBT and ABX: It's easy to produce negative listening-test results. Just use an equipment that the test person isn't intimately familiar with and let it play in an unfamiliar listening room. Or play random music samples.
I know there are people pretending that they could hear the differences between amps or cables from the kitchen. They are just pretenders. It's not that easy. It's important to know that sound transducers are by far the least accurate device within a sound reproduction chain. The inaccuracies of amps are a few magnitudes smaller. So with an unfamiliar speaker or headphone it's very hard -- if possible at all -- to detect them. As soon as you know a sound transducer and its characteristic inside out, it's much easier.
BTW, I don't think anybody will deny that you can get used to a specific sound characteristic, such as the sound of your speaker or headphone system. Consequently a change of sound caused by a new component -- let's say new speakers -- will be immediately apparent. And this even if you haven't listened to them for some hours or even days. This examples puts the following, often cited claim into perspective: «...for your information, it takes less than one minute for your memory to distil to the point that your memory is completely invalid as a comparative device.» Another example: You haven't spoken to your mother since a few months. Suddenly the phone is ringing, and the first few words will let you recognize her voice, without her mentioning her name -- and this despite telephone sound quality.
Some more considerations to DBT: To enable the highest likelihood for detecting audible differences, it is extremely important to know which amp you listen to at the very moment. Of course not the type of amp, but let's name it amp A and amp B. The other (often used) variant, random music samples, is virtually doomed to produce negative results. Without anchor points within the chaotic pattern of sample series the ears are overstrained.
It's not like two almost identical pictures you can compare each time you change your line of sight within the fraction of a second, back and forth. With random music samples you get a constant change of signal shape, never will there be two identical sequences you can hear any time you like and compare any time you like.
So there are quite a few preconditions to fulfill for a promising DBT: extreme familiarity with the reproduction chain -- room acoustics, speakers, speaker placement --, if possible also with the recording(s), as well as a test array allowing the test person to choose between sample A and sample B any time. This scenario would provide almost real-world conditions, which I consider crucial. So, it's best, possibly mandatory, to absolve the test in the test person's listening room.
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