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  1. #11
    Senior Member Mnyb's Avatar
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    Is the headphone amp USB bus powered ?
    --------------------------------------------------------------------
    Main hifi: Rasbery PI digi+ MeridianG68J MeridianHD621 MeridianG98DH 2 x MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3 sub.
    Bedroom/Office: Boom
    Loggia: Raspi hifiberry dac + Adams
    Bathroom : Radio (with battery)
    iPad with iPengHD & SqueezePad
    (spares Touch, SB3, reciever ,controller )
    server Intel NUC Esxi VM Linux mint 18 LMS 7.9.2

    http://people.xiph.org/~xiphmont/demo/neil-young.html

  2. #12
    Senior Member Archimago's Avatar
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    Quote Originally Posted by Mnyb View Post
    Is the headphone amp USB bus powered ?
    No, the AUNE has its own wallwart. I used the RCA out on the back for the measurements. I bet you something like the Audioquest Dragonfly would measure even worse with the USB noise, asynchronous or not I suspect is irrelevant. Dont know if reviewers have commented.

    BTW any Touch TT3 modders reading this? Is it easy to go back to stock settings afterwards?
    Last edited by Archimago; 2013-01-27 at 12:06.

  3. #13
    Senior Member Mnyb's Avatar
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    Quote Originally Posted by Archimago View Post
    No, the AUNE has its own wallwart. I used the RCA out on the back for the measurements. I bet you something like the Audioquest Dragonfly would measure even worse with the USB noise, asynchronous or not I suspect is irrelevant. Dont know if reviewers have commented.

    BTW any Touch TT3 modders reading this? Is it easy to go back to stock settings afterwards?
    Just factory reset the whole thing hold the little button above the power conector for a while .
    --------------------------------------------------------------------
    Main hifi: Rasbery PI digi+ MeridianG68J MeridianHD621 MeridianG98DH 2 x MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3 sub.
    Bedroom/Office: Boom
    Loggia: Raspi hifiberry dac + Adams
    Bathroom : Radio (with battery)
    iPad with iPengHD & SqueezePad
    (spares Touch, SB3, reciever ,controller )
    server Intel NUC Esxi VM Linux mint 18 LMS 7.9.2

    http://people.xiph.org/~xiphmont/demo/neil-young.html

  4. #14
    Senior Member Mnyb's Avatar
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    There are two use cases .

    As digital transport or listening via analogue out .

    There is some merit to that something could happen on the analog outs not so likely that a connected dac exhibits differences when using it as transport .
    --------------------------------------------------------------------
    Main hifi: Rasbery PI digi+ MeridianG68J MeridianHD621 MeridianG98DH 2 x MeridianDSP5200 MeridianDSP5200HC 2 xMeridianDSP3100 +Rel Stadium 3 sub.
    Bedroom/Office: Boom
    Loggia: Raspi hifiberry dac + Adams
    Bathroom : Radio (with battery)
    iPad with iPengHD & SqueezePad
    (spares Touch, SB3, reciever ,controller )
    server Intel NUC Esxi VM Linux mint 18 LMS 7.9.2

    http://people.xiph.org/~xiphmont/demo/neil-young.html

  5. #15
    Senior Member Archimago's Avatar
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    Quote Originally Posted by Mnyb View Post
    There are two use cases .

    As digital transport or listening via analogue out .

    There is some merit to that something could happen on the analog outs not so likely that a connected dac exhibits differences when using it as transport .
    Good point Mnyb:
    I'll look into doing some Touch-as-transport comparisons with coaxial vs. Toslink, EDO with analogue outputs on/off.

  6. #16
    Senior Member Archimago's Avatar
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    MEASUREMENT: Lossless vs. MP3!

    As mentioned in the 1st post, I'm waiting for the results of my blind MP3 test...

    In the interim, I wondered if my measurement setup can be fooled by MP3. So, with the AUNE X1 still connected, lets run the test signal lossless vs. MP3 through and see!

    Summary results:
    Name:  Lossless_vs._MP3.jpg
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    Not bad! When condensed into a single number, the different MP3 bitrates look fine! However, here's an example where single digit measurements can be very deceiving.

    Frequency response:
    Name:  MP3_FR.jpg
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    Again, MP3 looks pretty decent. However, you can start seeing the lower bitrates drop off in the high frequency prematurely beginning with 128 kbps (green) in sequence. Noticeable effect with lossless compression but not bad...

    Noise:
    Name:  MP3_Noise.jpg
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    Once again, not bad... What can I say, silence doesn't need many bits to encode :-)

    THD:
    Name:  MP3_THD.jpg
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    The "money shot" right there! It's obvious we can now differentiate the lossless (white) from the lossy compressed. There appears to be a large gap between the distortion from 128 kbps (green) to the rest. 192, 256, and 320 kbps all congregate together pretty close and I suspect for many of us, this correlates to 192 kbps+ being quite transparent.

    This is why MP3 compression effect is probably similar to VERY SEVERE jitter distortion (? at least tens of nanoseconds) in that it's correlated to the signal itself beyond simply single sidebands.

    Conclusion:
    You cannot fool machines with psychoacoustics!!!

    Addendum:
    For those AAC/iTunes lovers, AAC is without question objectively better than MP3! Nonetheless - you still cannot fool the machine :-)

    Notice that even unreasonably high bitrate 400kbps AAC (yellow) still can be differentiated from the lossless (white).

    Name:  AAC_THD.jpg
Views: 994
Size:  23.9 KB
    Last edited by Archimago; 2013-01-28 at 01:53.

  7. #17
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    Interesting for me, in that I decided a while ago that 192 (VBR) MP3 was my line in the sand for mobile use.
    Darren
    Last edited by darrenyeats; 2013-01-28 at 10:00.
    Check it, add to it! http://www.dr.loudness-war.info/

    SB Touch

  8. #18
    Senior Member Archimago's Avatar
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    In a couple week - once I finish up the results of the MP3 test, I'll start cross-posting these measurements over to my blog with specific pages for the components / tests. Wanted you guys to have a first look, especially with the SB gear I have!

    I must say, I've learned a lot about the limits of my gear and maximizing quality of the output by doing this exercise... Some of the troubleshooting when I got strange results have been particularly enlightening about the thresholds of clipping and utilizing the E-Mu as a recording device. It's also provided for me a very tangible view of the state of my equipment's sound quality - at least in terms of the digital front end part.

    I'm in the process of putting together a "Touch as transport" series of tests for later today as suggested by Mnyb. Just finishing up some 24/192 measurements with the EDO kernel... I'm very impressed by the Touch's engineering and quality of components!
    Last edited by Archimago; 2013-01-28 at 10:12.

  9. #19
    Senior Member Archimago's Avatar
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    Quote Originally Posted by darrenyeats View Post
    Interesting for me, in that I decided a while ago that 192 (VBR) MP3 was my line in the sand for mobile use.
    Darren
    Yup. 192 VBR should be fantastic for mobile purposes! I think it's absolute nonsense when people say they can "instantly" tell a difference between high quality MP3 and the real CD in a car stereo! If this is true, then there's something very wrong with their MP3 player.

    Year ago, before the true VBR algorithm in LAME, I decided on 210 kbps with the old ABR algorithm when I first ripped my CD's. Of course, over the years, they've almost all been re-ripped to FLAC.
    Last edited by Archimago; 2013-01-28 at 10:27.

  10. #20
    Archimago.. this is lot of work !!! Great contribution to the board. Thx. Looking forward to see any difference in DAC output when the Touch is used as a transport with some mods applied (like TT3.0, Linear Power supply etc).
    Main
    Wellborne Labs Power Supply -> SBT -> Zu Ash Coax -> TACT Digital Integrated Amp-> Zu Wax Speaker Cables -> Newform Research R630. Power Conditioning by Running Springs Audio Haley
    Mobile
    FLAC Files->TECLAST T51 Mp3 Player -> Silver Cables -> Ultimate Ears Triple Fi 10

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