Modi 2U and D30 DAC: Deconstructing Amir's Hack Job Part II

Discussion in 'Source Measurements' started by purr1n, Jun 8, 2018.

  1. atomicbob

    atomicbob dScope Yoda

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    One set of D30 measurements in the can. Will need to repeat a few as I want to make certain I've double checked the suite before posting. There are some things that have been conveniently ignored and one or two strange behaviors I've not seen in any other DAC.
     
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  2. atomicbob

    atomicbob dScope Yoda

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    Vetting data and I believe another run will be in order thanks to some the challenges the D30 presents. Some measurements are fairly consistent over several runs, and some are not. Examples:

    Topping D30 spdif 1kHz @ -90dBFS take 1
    20180609-18 D30 SE 1 KHz -90 dBFS - spdif - t1.PNG

    Topping D30 spdif 1kHz @ -90dBFS take 2
    20180609-18 D30 SE 1 KHz -90 dBFS - spdif - t2.PNG

    Topping D30 spdif 1kHz @ -90dBFS take 3
    20180609-18 D30 SE 1 KHz -90 dBFS - spdif - t3.PNG

    Topping D30 spdif 1kHz @ -90dBFS take 6 with 8mS time window
    20180609-18 D30 SE 1 KHz -90 dBFS - spdif - t6.PNG
     
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  3. purr1n

    purr1n Finding his inner redneck

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    Hmm. I will verify with a -90db 1kHz signal later tonight. I can do a spectrum with the AverLAB. And a waveform on the Focusrite (but just subtract the 60Hz related carriers in your heads - well I could just focus on a single sine.)
     
  4. purr1n

    purr1n Finding his inner redneck

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    This is what I got for the Topping D30. The Focusrite has behaving well today - no AC or multiples on the line. This was through USB. Maybe I should try SPDIF?
    D30 -90db sine.png

    @atomicbob: Maybe the included switcher was bad? Can you try with an external LPS? Good thing you were open to investigation and didn't instantly condemn it, like how we know one other guy who would have.
     
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  5. atomicbob

    atomicbob dScope Yoda

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    I found one problem. It appears that a single ground to one channel output is insufficient for the D30 when it floats with respect to a solid ground. There is no ground on the SMPS. dScope inputs float. Usually I only need ground one channel and the DUT provides adequate ground to the other channel. Not so with this D30. Have to ground both channel outputs individually to obtain better results.

    I will be measuring with LPS as well. Unfortunately I want to repeat tests with dual grounds SMPS and then LPS. Schedule is such that I this is not likely to begin until coming weekend.
     
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  6. LetMeBeFrank

    LetMeBeFrank Won't tell anyone my name is actually Francis

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    Aw c'mon Bob, it's not like you have to drive 75 miles each way twice and spend only 4 hours with multiple other DACs along with it. You should be able to knock out some perfectly accurate expert measurements for a single DAC in, what, 30 minutes? /sarcasm

    Seriously though I appreciate your professionalism.
     
  7. astromo

    astromo Rando

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    A big thanks to @purr1n and @atomicbob

    It's great to get alternate data reported so that at the very least an odd man out assessment can be done (and in this case, it looks like there's a seriously odd man involved).

    I've never been convinced by the geishavatar guy. The sensationalism and hyperbole that he spouts are better placed in a cheap tabloid newspaper.

    When that sort of narrative is dressed up as science, my BS-o-meter naturally fires up. Unfortunately, I don't have the tools to objectively refute the diatribe. Thanks for helping to confirm what my good sense has told me.
     
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  8. purr1n

    purr1n Finding his inner redneck

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    There is a huge human element to measurements. Amir would have us believe that all we need to do is hook up the probes, press go (and calibrate the AP555 correctly before), and run though eight DACs and eight hours.

    I've said this a million times. Sometimes, for whatever reason, the results are wrong. The only way we know they are wrong is from human experience.
     
  9. Screwdriver

    Screwdriver Rando

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    I have been pointing people here and head-fi when people use Amir as their source for why they think Schiit sucks. All I get back is that everyone else but Amir is a tool of Schiit/Jason.

    I'll be the first to admit that I have no idea what these charts mean. I like how my Schiit gear sounds and that is all that matters. I will say that I took Symbolic/Applied Logic in college and looking at the arguments on both sides shows me that Amir uses an invalid argument as proof. He seems to be the odd one out showing errors and as more and more people run tests that match the majority, then he should correct his findings by re running them correctly, or he should STFU.
     
  10. Dzerh

    Dzerh Rando

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    ... "There are three kinds of lies: lies, damned lies, and measurements" :)
     
  11. Dzerh

    Dzerh Rando

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    Sorry, the lines confused me. What are they representing? And wouldn't it be visually better to have the same scale on both axes? Or I'm missing something?
     
  12. purr1n

    purr1n Finding his inner redneck

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    The ideal in that plot is a diagonal line. Where the result starts to deviate from diagonal is when the output analog levels no longer match the digital input levels. The D30 in this specific case, with my AverLAB, and in my environment, started to deviate from ideal at a higher digital input level than the Modi 2U. Therefore don't buy the D30!

    In reality, the results are too close to call. Buy the one that sounds better to you. Or buy the one where the DAC vendor has a website, in a language you can understand, and may perhaps return e-mails.
     
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  13. Dzerh

    Dzerh Rando

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    I understand that much, I just not sure that deviation of the topping's line from diagonal is a part of the joke or there is more behind it :)
     
  14. bobsherman

    bobsherman Acquaintance

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    It is because the amir is an audio god and we are just mere mortals. He knows and see what we can only wish!
     
  15. Forza AudioWorks

    Forza AudioWorks MOT: Forza AudioWorks

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    Personally I like the word 'amirbits'. It sounds nice and fits the story perfectly ;)
     
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  16. bobsherman

    bobsherman Acquaintance

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    I think the amir is controlled by powerfull forces not of this planet.

     
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