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Originally Posted by slim.a /img/forum/go_quote.gif
Let's assume for one second that jitter is audible.
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We know it is audible, at about 10ns according to B and G.
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People who say they hear difference between different transports usually notice changes in the following aspects: Soundstage & Imaging, Frequency extremes (deep bass and high treble) and low level details. |
But we do not honestly know how many of these actually do hear a difference and how many merely think they hear a difference. So what they say they notice may or may not have a basis in reality. So unless you have a sample proven to unequvocably be able to detect differences we are talking speculation here.
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Those same people take a lot of care in selecting the best DACs, interconnects, headphone amps and headphones. None of them would consider the Sony MDR V6 as being revealing enough for those characteristics. |
Best defined as what ? Highest priced, most lovingly reviewed by Stereophile, FOTM ? What reliable criteria makes item X better than Y especially when we are talking about a very specific discrimination test. I have never heard the Sony's but I think they have been used quite heavily in studio environments where the ability to pick out differences may be important ?
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So do you honestly believe that the Sony MDR V6 was good enough to reveal changes in soundstage, low level details and frequency extension at the extremes? |
This begins to look a bit like snobbishness. That the Sony's are not a boutique headphone does not mean that they cannot be used to detect distortion. Again they have a good FR and low distortion, that they are not $1000 is neither here nor there.
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Wouldn't a set up similar to the one used by M. N. Kunchur help get more accurate results? |
I could not possibly speculate except to say it seems to have nothing at all to do with listening to music which formed part of B and G's tests.
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There is limited measurement of the DAC used. We don't have detailed measurement nor the kind of design (power supply, output stage, feedback, ...). Again, if you refer to Kunchur research, you will see that one has to be careful when selecting test equipment. |
The DAC used: DAC B had a Dynamic range of 105 dB.SNR. I would have liked to see precise FR figures but I don't need to know what power supply was used. If it had a flat FR and low distortion that is all that is necessary on top of its known jitter rejection.
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I always thought that science meant a critical approach. But sadly, it doesn't seem to be the case here.
If you really convinced yourself that their method and tools were beyond reproach, I am really saddened for you. |
A forced choice model would have been a better method rather than up-down, that is a fair criticism , but that is more likely to produce more generous results i.e subjects reporting false detection. Beyond that the methods look ok to me, they keep all variables the same except one.
As for critical approach, part of my working life is reviewing academic papers for journals and conferences, I am fully aware of the value of a critical approach.
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Scientists are not gods, they make assumptions and they also make mistakes. It has happened in many fields other than the audio industry. Kunchur's work is a step in the right direction. He didn't make assumptions about what was good enough and had surprising results. He could have used crappy equipment and concluded : the temporal resolution of human hearing is less than what we expected. Would that have been true according to your standards? |
Kunchur lowers the temporal resolution to say 4.7 microseconds, which is interesting in itself and a decent enough finding, Krumbholz (2003) already had it at ~10 microseconds so this is a decent refinement but it is not orders of magnitude different. A microsecond is 1000 nanoseconds. In terms of jitter this is an eternity and orders of magnitude worse that what we get in real world kit. And again unless you listen to signal generators which, contrary to what some folks think, I do not, this is wholly moot, the best audio system cannot reproduce the conditions that Kunchur created so you will never be in a position where anything you actually listen to will show this limitation even under the most extreme test.
More broadly, I find it somewhat amusing that the folks who are the most fervent jitter-worriers always hedge and fudge when empirical jitter papers are discussed but cannot point to a *single* reliable study that shows jitter to actually be an audible problem.