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

  1. #41
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    Quote Originally Posted by mansr View Post
    I think what they mean is that the cable between computer and REGEN matters less than if it connected directly to the DAC.
    Thanks. But what good would that be if it just shifts the dependency to the cable feeding the Regen?

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    Quote Originally Posted by jkeny View Post
    For someone who preaches quiet often about bias, I'm surprised that you don't recognise the very high likelihood of a biasing effect when doing measurements before sighted listening? So, in answer to your question - you have gotten the wrong end of the stick - the measurement results affecting your auditory perception is what I'm suggesting
    As I just noted and will repeat, we are not debating what I did or did not hear. You all have ears like me and don't need my listening experience to add to your convictions. What I can uniquely do in the forum is use my measurement equipment to try to figure out what this black box does. I am not at all hurt or worried about reliability or lack thereof of my listening tests. So dismiss them and note that such talk is beyond the scope of this subforum.

  3. #43
    Quote Originally Posted by amirm View Post
    Thanks. But what good would that be if it just shifts the dependency to the cable feeding the Regen?
    The Regen is small enough that it can easily be placed very close to the DAC, so there's that. Once might also suppose that even a bad cable from Regen to DAC, starting out with a clean signal, would be better than the same cable starting out with a dirty signal directly from the computer. All this is of course predicated on the Regen being useful at all, which as we've seen is far from evident.

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    Quote Originally Posted by amirm View Post
    I don't know. My suggestion is to re-test with an assumption that the device can do nothing or even harm the sound. Then see if it improves the sound still. The notion that 99% of other people said it makes thing sound better is a powerful bias.
    Hmmm, exactly my point about you doing measurements before listening - a very powerful bias for a particular mindset!


    It could be a lot. But not because of the reason you mention . My mission was to verify the technical aspects of the product. It said it cleaned up the USB signal, ergo it cleans up the output of the DAC. That didn't turn out to be the case. If the improvements were as universal as you said, then probabilities would say that it should have occurred in my test system and my listening room. Again I could not arrive at that conclusion based on listening or measurements.
    Amir, I believe this is what people on this forum have in the past objected to - your arrogance in making such categorical statements. You admit you could be missing something in your measurements (could you even be measuring the wrong things?) & yet you proceed to make these categorical declarations. I've already pointed out a different possibility to your original statement about the Regen's 8Khz 16KHz (& no doubt other harmonics) spurs. Do you really mean to be so categorical?


    In a science thread I am not digging deeper in this area. We are here to discuss the objective data which cannot be doubted as easily as what I did or did not hear.


    Oh? So what was the outcome with the supplied cable? Were those reports not so positive?

    As I post earlier the manufacturer advertises that reduces dependency on cables: "Although the REGEN does not eliminate all sound quality differences between USB cables in a high-end system, it significantly reduces those differences. "

    How is what you say possible when they say that cable should not matter as much and supply a short one instead?

    Do we now have two USB cables we need to tweak to get better sound, one to this device and one to the DAC?
    Do you genuinely want to find out if the device has an effect or are you trying to attack a device & prove something?
    Manufacturer digital products www.Ciunas.biz
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    Quote Originally Posted by amirm View Post
    As I just noted and will repeat, we are not debating what I did or did not hear. You all have ears like me and don't need my listening experience to add to your convictions. What I can uniquely do in the forum is use my measurement equipment to try to figure out what this black box does. I am not at all hurt or worried about reliability or lack thereof of my listening tests. So dismiss them and note that such talk is beyond the scope of this subforum.
    So why report your listening tests in the first place then?
    Amir, it is this attitude that you always have to be correct which is most bothersome to many!!
    Manufacturer digital products www.Ciunas.biz
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  6. #46
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    Quote Originally Posted by jkeny View Post
    So why report your listening tests in the first place then?
    I explained why. Because I was asked repeatedly to do so.

    Amir, it is this attitude that you always have to be correct which is most bothersome to many!!
    MOD: This is a formal warning. We are not going to have any talk of the forum being this and that and personal commentary of this sort. If the thread is bothersome to you, don't read it. Further comments of this sort will result in sanctions.

    We created this subforum to be free of this kind of commentary. I on purpose put the word "science thread" in the title. I put a note in there saying to not come here and say but your ears say this and that. Despite all of this, we get posts like this.

  7. #47
    Quote Originally Posted by microstrip View Post
    Surely, we understand it. But if your listening had shown any difference probably you would have looked for another type of measurement that would show a difference. At less it is what I expect scientists to do.
    Why don't you suggest some other measurements?

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    Quote Originally Posted by mansr View Post
    Why don't you suggest some other measurements?
    Because I am not an expert in DAC design.
    At last settled around the DCS Vivaldi 2.0 stack and a pair of Wilson XLF's : Forsell Air Force One, ARC Phono 2SE, cj GAT 2, cj ART monoblocks , TA OPUS MM2 IC's and sp, TA XL digital, TA XL gen V power cables, CenterStage footers and Nordost Qkore8's!

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    Quote Originally Posted by amirm View Post
    You have not John. So it is clear, I have read all of those posts. What I am after is him explaining how it is typical for USB to have such poor response in application of playing music. I take at face value that he has a computer and it spits out the performance he is showing. I don't doubt his method of measurement and the graph at all.
    But you suggest that it is a rogue USB port or rogue computer - so it's not exactly "at face value" now is it?

    And to be clear, nothing he has post is at odds to what I have reported. Nothing! I take it as a given that the hub in Regen produces a clean signal since it is outside of the computer and regenerates the bus yet again. That he shows this to be case simply confirms my basic assumption.
    Hold on a minute - did you not say that it introduces extra distortions? I can't see where you said it produces a clean signal - can you point to this?

    As I explained earlier though, we don't listen to USB bus. We listen to the output of the DAC. I measured this response. JohnW did not. So again, what he reported and what I reported are not at odds. It is not like he measured a DAC output and found that profound difference. He did not.
    And as I said he is intending to use a spectrum analyser on the output of his DAC for further analysis

    Unfortunately as we see from the response of the manufacturer and forum posts, everyone is running with that eye chart as that as if that is the sign of what improvements come out of the DAC itself. JohnW himself warns about not doing that later in that thread but it is just a line compared to the pretty graphs.
    When looking at any device, it is instructive to see it's immediate effect & if possible, trace the repercussions of this effect through the rest of the chain. Often it is far more difficult to measure effects further downstream unless one knows what specifically to look for & possibly design one's measurements to best reveal this. The jitter test is a good example - it was designed to uncover inter-symbol effects in SPDIF receivers, & one may well argue that without this specificity jitter may well have remained a boogey man. BTW, I've said it often that this general purpose "jitter test" being run on USB digital devices is a misapplication of such a test - why call it a jitter test why not a single tone test?

    So again, there is no conflict between JohnW's measurements and mine. His are measuring USB, I am measuring the DAC output." One doesn't predict the response of the other. You as a listener and buyer need to decide which data is more useful to you. I think it is the DAC output but you are welcome to think otherwise.
    Amir, as I said above measurements should be approached in a methodical way & not jumping to the end point where it is often more difficult to measure differences. If this logic is to be followed then we should dispense with all measurements apart from those that come from the speaker - that is what we listen to, right?
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  10. #50
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    Quote Originally Posted by amirm View Post
    I don't know. My suggestion is to re-test with an assumption that the device can do nothing or even harm the sound. Then see if it improves the sound still. The notion that 99% of other people said it makes thing sound better is a powerful bias.
    The number of positive reports (about the Regen) is just too big, feedback too unanimous/similar in contents for it to be powerful bias alone (to me). Also I was one of the first of the customers to report that the standard SMPS was a deal breaker for me and that a linear PSU was needed in my system to really improve SQ. I think this shows I'm a critical listener and customer. Yes, this is all merely anecdotal and hardly scientific but I think it is significant enough to question the validity/completeness of your measurements.

    Quote Originally Posted by amirm View Post
    It could be a lot. But not because of the reason you mention . My mission was to verify the technical aspects of the product. It said it cleaned up the USB signal, ergo it cleans up the output of the DAC. That didn't turn out to be the case. If the improvements were as universal as you said, then probabilities would say that it should have occurred in my test system and my listening room. Again I could not arrive at that conclusion based on listening or measurements.
    The primary purpose for the REGEN was that it builds a new wave form with better signal integrity. To quote Alex C.:

    Just as reminder to those just joining, the REGEN performs 2 completely separate functions:

    1) For the data it produces a entirely new USB signal of high integrity (that's rise-time, amplitude, edge-jitter, noise, etc.--all the stuff seen with an eye-pattern test) and proper impedance match--right at the input of the DAC so that the DAC's own USB input PHY chip and processor stay "calm" and generate less ground-plane and packet-noise INSIDE the DAC. This is the big thing that differentiates the REGEN from all other current devices.

    2) For the USB power side we completely ignore the 5V coming in on pin 1 of the USB cable and use the best-in-class 1A ultra-low-noise regulator, the TI TPS7A4700 along with a ultra-low-ESR 220uF capacitor, etc. to provide clean 5VDC to DACs that require it.
    I don't know why you can't hear any improvements (or deterioration) in SQ, it contrasts with the opinion of many owners and reviewers. Perhaps some other issue is masking it.

    Also there are reports that some devices don't benefit from using the Regen (I remember Melco and some Aurenders). As soon as a regular computer is involved however almost everyone is very positive.

    Your measurements show that USB power quality is improved. The measurements of John Westlake (that you question) show the improved signal integrity. NB. I think you may find John W.'s explanation of his measurements interesting: http://www.pinkfishmedia.net/forum/s...&postcount=710

    Quote Originally Posted by amirm View Post
    In a science thread I am not digging deeper in this area. We are here to discuss the objective data which cannot be doubted as easily as what I did or did not hear.
    Fair enough.

    Quote Originally Posted by amirm View Post
    Oh? So what was the outcome with the supplied cable? Were those reports not so positive?

    As I post earlier the manufacturer advertises that reduces dependency on cables: "Although the REGEN does not eliminate all sound quality differences between USB cables in a high-end system, it significantly reduces those differences. "

    How is what you say possible when they say that cable should not matter as much and supply a short one instead?

    Do we now have two USB cables we need to tweak to get better sound, one to this device and one to the DAC?
    Correct, the result with the short cable is less than with the solid adapter, so these reports were less positive (but not negative). Uptone Audio is honest enough to confirm this but has also explained why they chose to include it anyway. I've seen many people that can't use the solid adapter search for alternatives, some have found one in a short and expensive Aqvox cable.

    When Uptone Audio speaks about SQ difference between USB cables they're talking about the cable connecting the source to the Regen. The Regen is designed to be connected as close to the DAC as possible to (among other reasons, see Alex C. quote, bullet 1, above for all) ensure a proper impedance match. If I remember correctly they've even researched the possibility to solder a connector to the Regen internally to connect it to the DAC directly, without any adapters, but found this too impractical/limiting it's use for a broad spectrum of devices.

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