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What's wrong with level matched unsighted component comparisons

post #1 of 18
Thread Starter 
In a thread discussing CDP differences, a central recurring theme was that level matched unsighted comparisons are the gold standard. In the audio world this is often refer to as DBT or ABX testing. It is full of folly and discussions have been found to lead to nasty conclusions. The text below is quoted from AA


...DBT and ABX tend to force polarization and quickly degrade into death spiraling flame wars.

Is DBT bad?

Some think so. Others do not. From a strictly scientific viewpoint, DBT has proved to be the only method that is generally accepted for determining the audibility of small differences between audio equipment and cables. It does work.

A problem exists when these tests are either done poorly or when specific results are extrapolated erroneously. DBT is also not necessary for determining personal preferences.

What's the difference between DBT and ABX?

DBT is a scientific methodology. Some believe that ABX is closer to a religion. ABX is actually a sub-set of DBT. Years ago, a group of audiophiles developed a box that was dubbed the ABX Double Blind Comparator. The purpose of the box is to allow fast switching between two things to be compared, A versus B.

Fast instantaneous switching has many advantages. One's audio memory is short. Research has shown that one is more accurate in detecting small differences when the time between test stimulus is reduced.

The controversy then becomes the question of what effect the ABX box may have on the audio signal. Is the box totally transparent? What effect does adding additional cabling have on the results? Proponents would argue that these issues are irrelevant and that the advantages of fast switching out weigh any possible problems that are non-existent anyway. Opponents simply roll their eyes and respond with, 'Get a clue'. Discussions get nastier quickly.

Isn't this being unscientific?

Again, some may think so. In reality, there are many methods for determining preferences and accuracy of audio components. Measurement data is far more accurate than one's ears. DBT is simply one procedure. DBT does a great job in removing bias from comparisons. However, DBT does not imply that differences do not exist, only that these differences in this test, are below the levels of general audibility.

Many people feel that the true character of individual components is only realized after long term listening and living with the component in question. These people would argue that it takes time to fully appreciate or understand certain subtle differences that exist in various audio components.


...just a messenger,
PeAK
post #2 of 18
Nothing precludes one from doing a long term level matched, unsighted comparison.
post #3 of 18
While I am suspicious of DBT or ABX (more so for ABX) I did participate in a DBT of the failed DCC format, correctly identifying CD Vs. DCC 8 out of 10 times. I guess my point is...you either hear a difference or you don't. Any scientific attempts to remove variables and bias should be welcomed, not dismissed out of hand.

Many of us really believe that electronic components especially have different sonic characteristics, and rightly so. Yet it would be interesting to get perfectly matched levels and try to determine if the differences are real on the same system at the exact same volume.
post #4 of 18
Quote:
Originally Posted by peakrc View Post

In a thread discussing CDP differences, a central recurring theme was that level matched unsighted comparisons are the gold standard. In the audio world this is often refer to as DBT or ABX testing. It is full of folly and discussions have been found to lead to nasty conclusions. The text below is quoted from AA

...just a messenger,
PeAK


Yes, that was included in their website after some nasty battles. This is the person of great knowledge in these matters who was instrumental and to the best of my knowledge is the author

http://home.comcast.net/~retired_old_jj/
post #5 of 18
Quote:
Originally Posted by ChickD1 View Post

While I am suspicious of DBT or ABX (more so for ABX) I did participate in a DBT of the failed DCC format, correctly identifying CD Vs. DCC 8 out of 10 times. I guess my point is...you either hear a difference or you don't. Any scientific attempts to remove variables and bias should be welcomed, not dismissed out of hand.

Why are you suspicious?

Don't know about that failed format But, 8 of 10 is not at the 95% confidence level. More testing would be needed.

Quote:
Originally Posted by ChickD1 View Post

Many of us really believe that electronic components especially have different sonic characteristics, and rightly so.

Why would this be only a belief and not of knowing?

Quote:
Originally Posted by ChickD1 View Post

Yet it would be interesting to get perfectly matched levels and try to determine if the differences are real on the same system at the exact same volume.

Well, you have a bit of leeway here. Only .1 dB spl match is needed. A good voltmeter can do this.
post #6 of 18
The Asylum is full of holes and takes money from hi end companies so of course they dont want any kind of testing. The key in that whole writing is what all audiophilles use, that being I can hear so it must be true. No one ever wants to take into account the fact that the ear and beain are fooled by so many things.And that the hi end companies have not changed physics. Also none of the hi end companies ever do peer reviews of these great finds or present at things like AES.Some even o so far as to make up new definitions of things to fit what they sell.
post #7 of 18
Quote:
Originally Posted by CharlesJ View Post




Why would this be only a belief and not of knowing?




Very good question that deserves answering.

How many people here "believe" that speakers sound different? Anyone? Why is faith involved in cd players but not speakers?
post #8 of 18
Quote:
Originally Posted by tanaka View Post

Very good question that deserves answering.

How many people here "believe" that speakers sound different? Anyone? Why is faith involved in cd players but not speakers?


No, we know that speakers are different. No need to believe when it can be demonstrated under proper protocols.
post #9 of 18
Quote:
Originally Posted by CharlesJ View Post

No, we know that speakers are different. No need to believe when it can be demonstrated under proper protocols.


You didn't understand my post. I agree with you.
post #10 of 18
Quote:
Originally Posted by tanaka View Post

You didn't understand my post. I agree with you.


OK, I see your post differently now
Hey, it happens, from time to time.
Thanks.
post #11 of 18
level match? at what frequencies? using general pink noise or white noise and get an average?
post #12 of 18
Quote:
Originally Posted by cpu8088 View Post

level match? at what frequencies? using general pink noise or white noise and get an average?

Tom Nousaine level matches, or at least checks levels at 100Hz, 1kHz, and 10kHz. Seems to work for him very well with those 3 points.
post #13 of 18
differences usually show up when using the extreme ends such as 20-80hz or above 10,000hz. so matching the mid low, mid and mid high may not be adequate
post #14 of 18
Level matching with pink noise will yield consistent results, if one has an accurate enough measuring system.
post #15 of 18
Quote:


differences usually show up when using the extreme ends such as 20-80hz or above 10,000hz. so matching the mid low, mid and mid high may not be adequate

If so, that would suggest there should be a greater amount of positives. Making sure you at least match in the middle, 1 kHz, is important because it is in an around that range that our hearing is particularly sensitive.
post #16 of 18
Quote:
Originally Posted by Chu Gai View Post

If so, that would suggest there should be a greater amount of positives. Making sure you at least match in the middle, 1 kHz, is important because it is in an around that range that our hearing is particularly sensitive.

The 1kHz example is ideal for level matching with the Radio Shack meter, which is normally what the typical guy will have at home. Good point.
post #17 of 18
Maybe your meter. Not the RS.
post #18 of 18
Quote:
Originally Posted by cpu8088 View Post

differences usually show up when using the extreme ends such as 20-80hz or above 10,000hz. so matching the mid low, mid and mid high may not be adequate


The problem with this is that the ear is much less sensitive to variations at these ends than in mid band:

http://www.provide.net/~djcarlst/abx_crit.htm

The JND at 16kHz is 3 dB spl compared to about .2-.3 around 1kHz-4kHz.
Looking at the citation above, similarly high variations applies at the low bands. So, it is most crucial in the mid bands.
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