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Old 21st July 2010, 05:51 PM   #5001
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Gentlemen, and any ladies...

We have several co-existant things (variables) floating about here. It's important to be aware of them, and take them into account.

- measured "distortion" does NOT correlate to "subjective fidelity."
- a source of "extra" euphonic coloration MAY cause a system that has "extra" artifacts of very low level but higher order harmonics to "sound right." (even if the system specs at "low distortion")
- the whole thing is a fairly large compromise to begin with, so the expectation of more is not realistic.
- ...something else that escapes me at the moment that is important, so it will have to wait to be mentioned later...

My beef with DBTs that I am aware of (fyi, SY, and others) is that no one seems to be nailing down these "confounding" factors when publishing their test results - sure they are "correct" but only for the specific test conditions, which may or may not have various flaws that are undocumented.

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Old 21st July 2010, 05:56 PM   #5002
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Quote:
Originally Posted by Rod Coleman View Post
. I do listening tests with a second opinion (first in weighting) - one of the longest serving sopranos at Armonico:

Armonico Consort - Home

?
Funny when I said an expert luthier, a professional gutarist, and a music instructor at Berkely could not tell the difference in an open loop FET and TL-082 as a guitar pickup, I was told that musicians make bad listeners. BTW they all were given instruments blind and practiced/played at their own comfort and leisure.
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Old 21st July 2010, 06:01 PM   #5003
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Quote:
Originally Posted by bear View Post
[snip]My beef with DBTs that I am aware of (fyi, SY, and others) is that no one seems to be nailing down these "confounding" factors when publishing their test results - sure they are "correct" but only for the specific test conditions, which may or may not have various flaws that are undocumented.

_-_-bear
I agree that there may or may not be confounding factors; nothing in life is perfect, and DBT's aren't either. BUT, most DBT's do carefully list the circumstances and conditions, and try to keep it as objectively (controlled) as possible and try to use more than a single listener to get a statistically relevant result.
That is much, much more that a subjective, 'I sat down, plunket up a CD and I found that xx sounded muchg better than yy'-type of totally uncontrolled event.
To put more trust in such an anecdotal event than in a reasonably well set up DBT is only logical if you are unwilling to give up your believe.
Which is your prerogative, of course, but let's then recognise it for what it is.

jd
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Old 21st July 2010, 06:07 PM   #5004
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John,

I wanted to reply to your message above and for some reason my reply seems to have replaced your post. Don't know what happed I'm sorry!

SY, as a mod, can you repair whatever happened?

jd
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Old 21st July 2010, 06:30 PM   #5005
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'fraid not, Jan. I'll have to look at the engine works to see what went wrong. My apologies to you and John.
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Old 21st July 2010, 06:32 PM   #5006
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Quote:
Originally Posted by scott wurcer View Post
Funny when I said an expert luthier, a professional gutarist, and a music instructor at Berkely could not tell the difference in an open loop FET and TL-082 as a guitar pickup, I was told that musicians make bad listeners. BTW they all were given instruments blind and practiced/played at their own comfort and leisure.
That's because you ended up at the wrong conclusion, silly. If a test gives you the answer you don't want, blame the test. First rule of high end audio.
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Old 21st July 2010, 06:45 PM   #5007
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Jan,

The usefulness of the published DBTs is something I question. No doubt that they may be of value. However, I have yet to read a published DBT that actually printed the results of measured and in-situ tested equipment. And by that I mean more than just the IM and THD of the amplifier(s) - although that would be a start. I think I've made this complaint before - the ones that i have read are insufficiently documented such that one could actually replicate the test conditions to any degree of reliability or certainty.

Put this another way - I have heard perfectly "good" systems that use gear that is presumably of "low distortion" and "good engineering" that to me personally sound like "dog poop", meaning that I couldn't discern one thing from another. A DBT test on such a system would be statistically valid, but imo quite meaningless beyond that particular system.

I've also heard systems that are actually "ok" but they were so horribly set up that again, I found it impossible to really hear enough of what was going on so that I would be comfortable making any determination as to a "component" being one way or the other...

I still like the IROC/NASCAR analogy - all the right parts set up just a bit wrong and the thing slams into the wall on the curve...



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Old 21st July 2010, 06:48 PM   #5008
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Scott,

Your anecdote is not surprising at all.

There are two main problems with "professional musicians" and sound.

1. Some have lost a significant part of their hearing as the result of being over-exposed to amplified music.

2. Most musicians who have significant training "hear" the music in their heads - not in the "air". This is especially true of those who can sight read music... it is a problem in some situations.

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Old 21st July 2010, 07:07 PM   #5009
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Originally Posted by abraxalito View Post
Please do flesh out the relationship of DAC setttling time to timing errors if you can, its something that's been a bit of a fuzzy area for me for a while.
In a linear network for a perfect step you get 100% of the settling on final value in 100% of the time allowed. An RC network settles to 63.7% of the value in one time constant (R*C = 1 time constant). It then settles to 63.7% of the remainder in the next time constant. (76.9% of final value) Of course it will never actually reach the final value, so custom is to allow 5 or 7 time constants. Since you want fast settling higher order filters are use.

So if your timing accuracy is really bad say 1% then a linear system will have a 1% level error, the inverse exponent system having dropped faster at first will have less error. With zero timing error the linear system should have no error and the inverse exponent must have some.

So if all your steps are single bit both methods are nice, but when you do a step of 1/2 full scale linear should still be zero error and inverse exponent will have the single bit remainder multiplied by the step size.
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Old 21st July 2010, 07:12 PM   #5010
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Quote:
Originally Posted by bear View Post
Jan,

The usefulness of the published DBTs is something I question. No doubt that they may be of value. However, I have yet to read a published DBT that actually printed the results of measured and in-situ tested equipment. And by that I mean more than just the IM and THD of the amplifier(s) - although that would be a start. I think I've made this complaint before - the ones that i have read are insufficiently documented such that one could actually replicate the test conditions to any degree of reliability or certainty.

Put this another way - I have heard perfectly "good" systems that use gear that is presumably of "low distortion" and "good engineering" that to me personally sound like "dog poop", meaning that I couldn't discern one thing from another. A DBT test on such a system would be statistically valid, but imo quite meaningless beyond that particular system.

I've also heard systems that are actually "ok" but they were so horribly set up that again, I found it impossible to really hear enough of what was going on so that I would be comfortable making any determination as to a "component" being one way or the other...

I still like the IROC/NASCAR analogy - all the right parts set up just a bit wrong and the thing slams into the wall on the curve...



_-_-bear
Bear, I'm sure you can find fault at anything you want if you look good enough (and I don't mean 'you' personally, but in general). My point is that published DBT's, with all their flaws and shortcomings, real or not, are infinitely more reliable than a casual, subjective, non-documented test with a system that's totally in the dark. Except, of course, for YOU.

Compare for instance that well-documented test that Ivor Tiefenbrunn flunket with a 'test' done by me or you sitting at home and plugging an ADC-DAC in or out of our system and then telling all the world that I/you clearly heard a difference, that the DAC-ADC "destroyed the realism" or whatever. Is it unreasonable to have more trust in my/your results than in the Tiefenbrunn test results, except if you are unwilling yo give up your believe. Which is my/your prerogative, but let's recognise it for what it is.

jd
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