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In Reply to: RE: It would be a deal-breaker for me indeed.....to this reviewers credibility. posted by dave789 on January 02, 2015 at 18:26:05
If there was some kind of a ground loop it might be hard to track down the cause. It might disappear when different equipment is used. Or it could be hum in the digital source that is causing jitter that the ASRC in the benchmark filtered out. Or, (most likely) it could be defective power supply components in the Peachtree DAC clock circuitry.
I would bust the reviewer for calling the product's sound "neutral" while it had such gross hum modulation of the audio signal. He should have heard something wrong with the DAC's sound. One would hope that a reviewer who can't hear problems would at least be competent at measuring and interpreting results. This does not appear to be the case. (I've been to the web site and previously reached a conclusion about his reviews.)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
Follow Ups:
Do you think the reviewer did something (connection or placement) that no reasonable-minded audiophile in the world will ever do at home?
It is hi-fi designer's responsibility to make it jitter free in wide range of possible settings.
The reviewer is not wrong about not feeling the jitter sidebands. They are below the well known masking curve. Nothing dishonest about that.
It is of course possible that some other people hear that kind of jitter.
Hi,
> The reviewer is not wrong about not feeling the jitter sidebands.
Why not? Anyone who cannot hear hum at -60dBFS is pretty much deaf.
And FM at -60dB the same.
Of course, there is a good chance that when the unit was auditioned these hum components were absent (as I think anyone would have tried to eliminate such obviously audible problems).
As said, the problems are likely the result of not setting up the test correctly and overlooking something that would have been obvious to a competent professional.
Ciao T
At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to untolerable pain. Really, what more could we need?
They are not -60dbFS hum.
They are (11000 +/- 60)Hz tones below 60dB of 11000Hz tone. Please do internet search about masking curve.
Now what is the level 60Hz tone you are claiming to be induced by wrong set up? See the whole review and figure it out. Do not imagine!
The spectra with the spuria shows only a narrow frequency range. We don't know what the level was at 60 Hz during this test. This presentation, by itself, shows the incompetence of the reviewer. He should have given a complete spectra, followed by zooming in to the high frequency peak. I've seen more than my share of doctored graphs and charts. Shifting the axis is a standard method of lying by statistics. (These graphs are statistics, by the way.) In this case, however, I suspect incompetence rather than dishonesty. Given that the DAC didn't have a polarized plug, something as simple as reversing the power plug might have cured the problem.
Note that this reviewer is not a soft-touch, feel-good non-technical subjectivist audiophile. The web site trys to project technical expertise and is written from an objectivist viewpoint. I came upon this web site a few months ago and after reading an number of articles, I concluded that the web site was worthless, a relic of the Julian Hirsch reviews in Stereo Review.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
"Given that the DAC didn't have a polarized plug, something as simple as reversing the power plug might have cured the problem."
If reversing the plug can cause such a high jitter, then it is design defect or manufacturing defect. It is not at all fault of the user or the reviewer.
If the reviewer were competent he would have understood the possibilities and would have discovered and reported that the product sample was sensitive to ground loops. This would have been useful information. However, he did not do this.
I find it hard to know whether a product is good if I am forced to deal with information that comes through an obviously incompetent reviewer.
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
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