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Thread: Science Thread: Review of Audioquest Jitterbug and Uptone Regen USB Conditioners

  1. #61
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    Quote Originally Posted by Sal1950 View Post
    +1

    Amir, The anti-science voices are being allowed to go to far outside the rules here.
    TIA
    Do you mean anti-science or better-science voices? Personally, I'm looking for better science & let the cards fall where they may.
    Let's look at JohnW's approach to measurement of the Regen - he approached it in a structured way - he firstly measured his USB signal. Is it a rogue one, as Amir implied - I have no reason to assume this but maybe it is as he found a surprising level of low frequency noise riding shotgun on the USB signal waveform. This LF noise he observed was correlated with activity in the PC. Now, I know this is something that Amir has riled against in the past when the subject of different software players was discussed here so I'm not surprised that he riles against this report. BTW, the LF noise (or "runt events" as JW calls them) are seen as the blue shading on the eye pattern plot already posted.

    Having established the characteristic of the USB signal waveform & connection he then measured the ground plane noise on the output of the Regen with a linear PS & with the supplied SMPS PS. It showed the noise of the SMPS but, as a side issue, it showed the 8KHz noise that occurs from the USB protocol itself - something John Swenson, the designer of the Regen, has always maintained that the Regen isn't designed to attenuate.

    JW has stated that he will be doing some spectrum analysis of the DAC's output signal which I expect he will do so shortly.

    Having established the LF noise on the USB signal, I would imagine his DAC analogue output measurements will be directed towards establishing the effect of this LF noise here & it's attenuation upstream. I believe that any effect on the analogue outs will require very careful & focussed measurement, not some generalised "jitter" measurement.

    I would suggest that JW's approach is far more focussed than what we see here but maybe JW will find nothing? Who knows? However, what I am saying here is that we need to be more scientific & not presume that differences will leap out from general measurements.

    I know this will enter into the realm of measurements Vs auditory perception but hey, this is where I believe we are at in current audio progress - most of the low hanging fruit has already been addressed.
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  2. #62
    Quote Originally Posted by Superdad View Post
    Well here is some hard data for you:
    a) The $175 REGEN is sold with a 30-day, money-back, satisfaction guarantee;
    b) To-date we have sold 1,723 units;
    c) Exactly 8 people have asked for a received a refund on their purchase. That is less than 0.5%.

    -Alex Crespi, UpTone Audio LLC
    There is no data there that is relevant to this discussion.

    Tim
    In high-end audio, you can't even fight an opinion with the facts.

  3. #63
    Quote Originally Posted by Jud View Post
    There could well be. Still, I don't think talk of bias is any more germane than mention of positive reports in this thread. I await further test data with interest and curiosity.
    In this case, talk of expectation bias is just speculation on the cause of the positive reports, but make no mistake, expectation bias is science and IMHO has every business in a science thread. I will give you that it would be off-topic, had the anecdotal positive reports not been given as an answer to Amir's tests, but they were.

    Tim
    In high-end audio, you can't even fight an opinion with the facts.

  4. #64
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    Quote Originally Posted by jkeny View Post
    Do you mean anti-science or better-science voices? Personally, I'm looking for better science & let the cards fall where they may.
    L
    I don't believe so. You just wont be happy till someone can come up with some phony science to support the incorrect subjective listeners conclusions.

  5. #65
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    As usual, Tony's post is on target. This thread is what you get when non-scientists start to dabble in science. I went through this awhile back in another thread at this forum; in order for something to be considered "science", the scientific method needs to be followed. Amir's observations are just that, observations, which can be used as the first part of an attempt (following the scientific method) to try to establish (or not) a scientific fact. The next step, should anyone wish to take it, is to generate an hypothesis from these observations; then one should devise an experiment to try to test said hypothesis. The results of that experiment can be analyzed in an attempt to prove or disprove the original hypothesis. So the preliminary observations posted here are perhaps interesting but prove (or disprove) nothing.

  6. #66
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    Quote Originally Posted by Sal1950 View Post
    I don't believe so. You just wont be happy till someone can come up with some phony science to support the incorrect subjective listeners conclusions.
    Welcome to WBF Sal....

    the incorrect subjective listeners conclusions.
    Priceless....
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  7. #67
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    Quote Originally Posted by Tony Lauck View Post
    I did not find your work an adequate scientific study for two reasons:

    1. The "mission" is not broken down into separate questions, namely: (a) does the device (e.g. REGEN) improve the USB signal integrity? and (b) does this affect/improve the analog output of the DAC?

    (a) For me a scientific study would have required lab quality USB measurement equipment used. Measurements should have been performed to characterize the USB signal quality of a variety of computer sources, involving a variety of computer hardware, computer software and USB cables.

    (b) For me a scientific study would require a wide range of USB DACs, including those at a wide range of price points, together with comparisons of input waveforms (with and without the REGEN) and output waveforms. In addition the tests should have been formulated to avoid ambiguities, such as the ambiguity of the Jtest signals at 8 and 16 kHz being jitter vs. harmonics. There are enough variables involved that a range of test conditions are needed before it is possible to evaluate any cause-effect relationships. There was no experimental design or possibility of statistical analysis with the small sample of gear tested.

    I doubt I could have done any better. I don't have a hardware lab, let alone one costing six figures. But without the appropriate equipment and appropriate test methodology I would be forced to dabble, not do science.

    This may be a matter of personal style, but given the results you obtained with what is at best a preliminary investigation, I would not have published your measurements, as it is too easy to interpret them as denigrating a well regarded product. Had they been positive, then I would have been inclined to publish the results as preliminary measurements, but not make any attempt to justify that one is doing any kind of science, or even engineering. What you did strikes me as more appropriately a case of a technician doing preliminary testing of equipment to scope out if it is working, prior to any serious work being done.
    An excellent and well thought post. Thanks!
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  8. #68
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    Quote Originally Posted by Occam View Post
    Welcome to WBF Sal....

    the incorrect subjective listeners conclusions.
    Priceless....
    Actually, from a strictly scientific point of view, Amir's measurements are no more valid than someone's subjective listening impressions

  9. #69
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    A further follow-on step in JW's measurements - I find it a logical step for the next measurement to see it's effect in the next step along the signal path:
    Having measured LF frequency noise riding on the USB signal, here he's showing how such noise can infiltrate digital logic - a USB receiver, for instance http://www.pinkfishmedia.net/forum/s...postcount=1373

    He uses one of the simplest logic ICs, a 74HC04 & says this
    "The 74HC04 HEX inverter is the simplest logic gate you can find - in this test only 2 logic gates are operational - imagine the phase noise effect of millions of logic gates in a typical "complex device" such as a USB input device or a integrated DAC IC."

    "The purpose of this test was to demonstrate how external phase noise can cross domains at the digital level - this is why Memory buffers etc. offer jitter poor isolation unless VERY VERY carefully designed - and not as an integrated solution.

    Its also why its important even with an ASync DAC to insure that the USB input is as free of unwanted Phase Noise as possible"
    Last edited by jkeny; 09-29-2015 at 02:13 PM.
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  10. #70
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    Quote Originally Posted by Purite Audio View Post
    Perhaps the manufacturer should have performed these measurements , to establish the worth or otherwise of the product before release?
    Keith.
    How do you know they didn't?

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