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

  1. #11
    Member Sponsor Addicted to Best! dallasjustice's Avatar
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    Thanks Amir!
    MUSIC IS GOOD

  2. #12
    Quote Originally Posted by kevinkwann View Post
    LOL! Quite right. Once again, the emperor has no clothes despite his protestations to the contrary.
    I don't have time at the moment, but I can say that the tests are a bit flawed and that you are focusing on the wrong things. The REGEN's main purpose is to improve the signal integrity going into the DAC (such that the DAC's own PHY chip generates less packet-data-noise and ground-plane noise), and this is best measured with a very wide band scope and an eye-pattern test. John Westlake (a competitor in that he is planning, based on what he has seen with the REGEN, to develop a more elaborate, 3-stage version in a larger case that cant be placed at the DAC's input) did just that with a REGEN and had a host of compliments about what he saw. Here are the two eye-patterns he posted:

    Without the REGEN--
    Name:  direct usb.jpg
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    With the REGEN--
    Name:  regen usb.jpg
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    ==========
    And some quotes from him about the above measurements and his comments:

    "Above is a colour graded eye pattern of the Direct PC USB connection to an XMOS based DAC (streaming 1KHz, 0dB FS) High speed USB.
    Note the multitude of lines, but more importantly that the background is not black (Black means no data points fell in this area) - the background its dark blue because during the acquisition low frequency "Runt" waveforms where sampled in this area - these "Runt"waveforms occurred as the PC / operating system processed other applications / Operating system house keeping tasks etc. On the Analogue scope it was a horrific mess…
    Now with the ReGen USB Data, notice not only the much cleaner waveform but far more importantly that there is very little "Runt" data - the background is Black. The USB Hub IC in the Regen has for the most part cleanly repackaged the data."
    "I'd agree that the Regen resulted in the greatest measurable difference to the downstream USB Data."

    And a another post from Mr. Westlake with additional appropriate measures:
    This evening I tried using a real-time spectrum analyzers to look at the USB data, but basically my unit is design for observing narrower bandwidth RF transmissions then the 500MHz Span which is required to observe the USB spectrum. I’m rather disappoint the unit has proved to be so useless. I’ll replace it with the new unit from the US once it arrives – space is at too much of a premium in the lab.

    I made some further measurements with a faster digital analyzer 15GHz Band width – but it lacks the large memory for the deep color grading that the slower scope has, but it still managed to capture the LF events on the Direct USB PC connection.

    The Eye pattern of the direct USB connection at 200pS Div – note the LF Runt pulses are just visible despite the short sampling time:-

    https://dl.dropboxusercontent.com/u/...SB%20200pS.jpg

    The same 200pS Div measurement with the ReGen:-

    https://dl.dropboxusercontent.com/u/...en%20200pS.jpg

    No trace of LF Runt pulses – but a slightly higher jitter on the rising edge – but it’s the LF jitter that matters, which the Regen clearly improves upon.

    Direct USB connection at 500pS Div – again note the LF Runt data:-

    https://dl.dropboxusercontent.com/u/...SB%20500pS.jpg

    And via the Regen at 500pS Div, showing a cleaner Eye pattern without a trace of LF runt Data :-

    https://dl.dropboxusercontent.com/u/...en%20500pS.jpg

    As above but with the Jitter Bug fitted between the ReGen output and XMOS based DAC PCB.

    https://dl.dropboxusercontent.com/u/...JB%20500pS.jpg

    I’d almost suggest the Jitter bug degraded the crossing point jitter – I suggest its really designed to filter the power supply rail on the USB line which is most beneficial for USB powered DAC’s / Devices, but not so beneficial for self powered DAC’s like the MDAC.

    Any RF filtering is a good idea, but IMO the Regen offers better “Performance per pound” then the Jitter Bug for MDAC type designs which are self powered.

    Phase noise test of the ReGen's clock - measured from the Clock output pin on the USB Hub IC - I've seen worst

    Some odd components at 3.3KHz and beyond... but really not so bad.

    https://dl.dropboxusercontent.com/u/...MHz%20Xout.jpg

    -114dBC at 1KHz offset -133dBC @ 100KHz.

    ----------------------

    And with regards to the graphs of SMPS spread spectrum noise that Elberoth posted on this thread's first page, note how far down they are and how high in frequency. I won't defend the $12 SMPS we include with the REGEN (other than that this 7.5V/2.93A/22W model is better than the pile of others we tried in the range), and many people are using the REGEN with LPS units from modest to fancy (our own choke-filtered, dual-output, 5-7A JS-2 being one of them). But let's keep perspective here.

    I defies logic for there to be measured increases in jitter from insertion of the REGEN, so I suspect something is amiss with Amirm's testing. I will ask my partner, engineer John Swenson to review and comment upon that. By the way, you did not indicate what DAC or USB input you used in your testing.

    I would welcome further meaningful dialog about our popular product. With just under 2,000 units sold around the world and being used with DACs from modest to mega, do dismiss our device without really understanding how it works does not seem appropriate.

    Thank you and regards,

    --Alex Crespi
    UpTone Audio LLC

  3. #13
    Member Sponsor Addicted to Best! dallasjustice's Avatar
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    Amir,
    Did you write this thread during the "supermoon" last nite? If so, all of your findings are invalid and should be ignored as crackpot science.
    MUSIC IS GOOD

  4. #14
    Member Sponsor Addicted to Best! Elberoth's Avatar
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    Quote Originally Posted by kevinkwann View Post
    LOL! Quite right. Once again, the emperor has no clothes despite his protestations to the contrary.
    I think it is way too early for such a conclusions. The plots posted by Amir clearly show that it improves the quality of USB power A LOT. Now we need to find out why on the two DACs tested (or just one, Amir ?) Regen introduced some other, unexpected problems.

    Wether the benefits outweight the problems - that is a completely different story and may be very much system dependent.
    Adam

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  5. #15
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    Welcome to the forum Alex. Appreciate your participation and data added to the conversation.
    Quote Originally Posted by Superdad View Post
    I defies logic for there to be measured increases in jitter from insertion of the REGEN, so I suspect something is amiss with Amirm's testing. I will ask my partner, engineer John Swenson to review and comment upon that.
    It was surprising to me too but is what I got. Note that their levels is very low.

    By the way, you did not indicate what DAC or USB input you used in your testing.
    I did actually. I used the Meridian Explorer:



    I am unclear what you mean by "USB input." I used the short cable that came with the box to connect it to my USB port on my laptop.

    I would welcome further meaningful dialog about our popular product. With just under 2,000 units sold around the world and being used with DACs from modest to mega, do dismiss our device without really understanding how it works does not seem appropriate.
    This is a puzzling remark. What is "appropriate" for any audiophile is what sound is produced by the DAC. What the waveform looks like coming into it is of no concern. What is next? Checking to see what the CPU is doing???

    Eye pattern analysis is very useful for data communication where long lines are involved or very high speeds. Neither is the case here. No one is having reliability issues here with data loss. It is extreme misdirection to focus the issue on eye pattern instead of what is produced by DACs.

    I am looking to substantiate statements like this on your web site:

    "If you are familiar with the variations in sound quality that come from different computer configurations, USB cables, and power supplies (no, "bits are bits" really does not apply when pursuing the audio summit), then you will immediately recognize the often dramatic effect that the REGEN can have on the the connection you feel with the music."

    How would you connect the eye pattern on USB bus to "connection you feel with music?" None of us feel those pulses. We feel the analog signals coming out of the DAC through the rest of our system. You go on to say:

    "Although the REGEN does not eliminate all sound quality differences between USB cables in a high-end system, it significantly reduces those differences. "

    Is there some evidence of this? Any measurements you like to share?

    I like to understand how we can demonstrate this to be true:

    "From all the time we have spent listening to the REGEN in our systems we can say that it is exceeding our expectations. Often it sounds like you are listening to a different DAC! "

    None of my measurements indicate I am listening to a different DAC. Do you have some that do that?

    If the only advertising on your site was about the eye pattern, then you would have a case showing it such even though in our applications, data integrity is not a concern. But currently you talk about audible benefits with a technical explanation. We need to be able to connect these two somehow. I hope you appreciate that.

    Thank you and regards,

    --Alex Crespi
    UpTone Audio LLC
    Thanks again for joining us. I welcome any and all feedback you have on this topic.

  6. #16
    Member Sponsor Addicted to Best! Elberoth's Avatar
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    I just thought it would be interesting to quote John Westlake again on this topic:

    The Analogue scope measurements of the USB direct and ReGen USB revealed the truly "horrid" nature of the USB traffic from a PC with heavy "CPU Process" jitter modulation - and I've been trying to think how to graphically capture it so I can post it here on PFM.

    So I dug up a Digital scope - rearranged the lab to make space for it... I think its the first time I've really used it - I hate them, but it proved useful to capture the data.



    Above is a colour graded eye pattern of the Direct PC USB connection to an XMOS based DAC (streaming 1KHz, 0dB FS) High speed USB.

    Note the multitude of lines, but more importantly that the background is not black (Black means no data points fell in this area) - the background its dark blue because during the acquisition low frequency "Runt" waveforms where sampled in this area - these "Runt"waveforms occurred as the PC / operating system processed other applications / Operating system house keeping tasks etc. On the Analogue scope it was a horrific mess...



    Now with the ReGen USB Data, notice not only the much cleaner waveform but far more importantly that there is very little "Runt" data - the background is Black. The USB Hub IC in the Regen has for the most part cleanly repackaged the data.

    The colour grade data sample hit size is the same for both plots (20K Hits on the Red).


    Those plots clearly show that the Regen gets its primary job done (reducing USB jitter which should lead to reduced PHY noise). What is more John basicly validated Regen's concept by saying:

    Yes, I strongly believe that the USB Packet jitter cause "second order" effects in the MDAC (PSU, Ground plane and RF modulation).

    I realise that the MDAC's USB device (the TAS1020B) not only decodes the USB, but its also the house keeping processor on the MDAC mainboard - so its directly connected to the ESS DAC (via the ESS's I2C MCU configuration port) allowing multiple RF coupling paths between the external USB Host device (PC / Computer) and the ESS DAC.


    So what we see here is:

    1. greatly reduced noise on power line
    2. greatly reduced USB data jitter

    Now the 1 million dollar question everyone is asking now is, how it is possible that greatly reduced jitter and noise, induced more distortion in the DAC. Either we didn't measure the right thing, or there is other variable, that Amir's tests didn't account for (like the SMPS).

    I would very much like to see how this topic develops.
    Adam

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  7. #17
    Member Sponsor Addicted to Best! Elberoth's Avatar
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    Superdad's post just mysteriously appeared over my post - it was probably waiting for moderator's approval (1st post by Superdad) - chence double posting of the same graphs.
    Adam

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  8. #18
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    Quote Originally Posted by Elberoth View Post
    I just thought it would be interesting to quote John Westlake again on this topic:

    [I]The Analogue scope measurements of the USB direct and ReGen USB revealed the truly "horrid" nature of the USB traffic from a PC with heavy "CPU Process" jitter modulation - and I've been trying to think how to graphically capture it so I can post it here on PFM.

    So I dug up a Digital scope - rearranged the lab to make space for it... I think its the first time I've really used it - I hate them, but it proved useful to capture the data.



    Above is a colour graded eye pattern of the Direct PC USB connection to an XMOS based DAC (streaming 1KHz, 0dB FS) High speed USB.
    I came to post what he had written here and you saved me the typing .

    I must say, I am very surprised that a PC USB port would have such horrid eye output. Then I read the initial line that he is using some kind of "heavy "CPU Process" jitter modulation?" I don't know what the heck that is but this is not what I expect the eye pattern to be on a USB port with a short cable. I can't imagine the above eye pattern being from a USB compliant port.

    There is unfortunately no USB police to speak of so it is entirely possible for him to have an implementation that is not well implemented.

    Note that my laptop was simultaneously driving the DAC and my Audio Precision analyzer over USB. In typical server playback, assuming your music is not coming from USB, you would have a much quieter environment than mine. The CPU load in playing music is nothing, certainly lower than what I was doing in this measurement.

    Anyway, even if we are going to talk about eye patterns, we better show a broader spectrum of USB ports than one unknown one here.

  9. #19
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    Quote Originally Posted by Elberoth View Post
    Superdad's post just mysteriously appeared over my post - it was probably waiting for moderator's approval (1st post by Superdad) - chence double posting of the same graphs.
    We don't have moderator approval for first post so not sure what may have happened.

  10. #20
    [WBF Founding Member] Moderator RBFC's Avatar
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    I approved his post a bit ago. There were posts directed at Alex personally, and the post did not violate forum rules.

    Interestingly, Mark Waldrep of AIX records has already sent out his daily email complimenting Amir's post on this topic.

    Lee
    Lee Aldridge

    I post my own opinions except when posting as a moderator in green.

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