Schiit (MultiBit) Bifrost

Discussion in 'Digital: DACs, USB converters, decrapifiers' started by FlySweep, Oct 2, 2015.

  1. lm4der

    lm4der A very good sport - Friend

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    Without Wyrd, I have nothing new in device manager. It doesn't do the usb kdum kdum sound.

    With Wyrd I show:

    bimb1.png

    The device driver itself was automatically installed from the Microsoft site when I first plugged it in via the Wyrd:

    bimbydriver.png

    Pretty wyrd.
     
    Last edited: Oct 4, 2015
  2. lm4der

    lm4der A very good sport - Friend

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    Sorry, fixed the image above...
     
  3. lm4der

    lm4der A very good sport - Friend

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    Marv, maybe try uninstalling/removing the "unknown" device when plugged in via Wyrd - this will usually cause Windows to try to reidentify the device and download the drivers. It seems fine if they come down from Microsoft.
     
  4. lm4der

    lm4der A very good sport - Friend

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    Hi Jason, thanks for jumping in. I tend to agree with you that it's just my computers' usb ports, however... I am suspicious that there is a driver being downloaded from Windows Update when the Bifrost is first plugged in. This driver seems to work, but may be conflicting with the Schiit downloaded driver. That's purely speculative at this point, didn't feel like messing with it further today, as I am good through the Wyrd.
     
  5. purr1n

    purr1n Desire for betterer is endless.

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    Tried that. 1.03 drivers on laptop works. 1.16 didn't work anywhere. Still trying on the PC.
     
  6. lm4der

    lm4der A very good sport - Friend

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  7. Tuco1965

    Tuco1965 Suffring from early onset Alzheimer's - Friend

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    My Bifrost is packed and off to the post office in the morning. I can't wait for the return of the Bifrost Multibit. Hopefully round trip from Canada will be quick and painless.
     
  8. Mrip

    Mrip Friend

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    My Win 10 pc also gave the CMedia device error. After trying to install the drivers for a while I noticed that the dac was already recognized and working, with a C-Media driver. No idea. It works with and without Wyrd, but when I first realized it was working it was without the Wyrd.
     
  9. lm4der

    lm4der A very good sport - Friend

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    Yeah, my theory is that the driver you are showing auto installed from MS Window Update.
     
  10. lm4der

    lm4der A very good sport - Friend

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    EDIT: Ignore this, I think you updated your post right as I asked this, lol.

    Wait, Mrip, does it work for you without the Wyrd? I get nothing w/o Wyrd.
     
    Last edited: Oct 4, 2015
  11. purr1n

    purr1n Desire for betterer is endless.

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    UPDATE: Got 1.03 to drivers to install. Pulled everything except keyboard and mouse and did a full power down and restart.
     
  12. jacq

    jacq Top 3 poster - friend

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    I currently have a Mjolnir 2 but it'll take a little bit to buy the Gungnir MB which I plan to get eventually. Currently, I have an Adcom GDA700 PCM1702x2 DAC and running it in balanced with the Mjolnir 2.

    My question is, would the Bifrost possibly be better than what I have right now and is it worth running the Mjolnir 2 in SE? I'm very curious because I've never really had much experience with DACs to begin with. But I'm kind of worried that it might not be worth it to upgrade for my particular system. I'd like to hear some thoughts.
     
  13. Judeus

    Judeus Facebook Friend

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    pretty sure mjolnir 2 has a splitter for rca inputs so you will still get the full differential signal with the mjolnir as long as you used a balanced headphone cable
     
  14. ultrabike

    ultrabike Measurbator - Admin

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    Some comments...

    INL looks good (page 10 of http://www.analog.com/media/en/technical-documentation/data-sheets/AD5547_5557.pdf). Seems like a pretty fast converter.

    For the cases of audio multibit DACs, the PCM63P does indeed avoid providing specs for INL and DNL:
    http://www.ti.com/lit/ds/sbas006/sbas006.pdf
    Instead they go about it with this hand wave statement:
    "Even though absolute integral and differential linearity specs are not given for the PCM63P, the extremely low THD+N performance is typically indicative of 16-bit to 17-bit integral linearity in the DAC, depending on the grade specified. The relationship between THD+N and linearity, however, is not such that an absolute linearity specification for every individual output code can be guaranteed"

    Can't seem to find INL and DNL characteristics on the PCM1704 either:
    http://www.ti.com/lit/ds/symlink/pcm1704.pdf

    Anyhow, now for delta sigma, things become a bit more interesting. DS output depends on preceding samples and has memory (though not much more than most analog reconstruction filters in a DAC). However, while the static INL and DNL test may throw light into current source or resistor non-idealities in an R-2R architecture, these issues may not affect delta sigma the same way, and the tests to some extent may not be that meaningful.

    Furthermore, consider that even if a delta sigma output depends on it's previous state, it eventually settles. With proper dithering and with a few levels of quantization, limit-cycle issues disperse. With the limit-cycle issue and what not gone, consider that one thing delta sigma does very well is DC, and may do decently on an INL/DNL test. But again, the results will not provide a lot of insight into resistor or current source errors as it would do for R-2R designs.

    It's still a 16-bit part though. Quantization noise is still noise. Ironically, if those specs are true, one might be able to squeeze more bits out of the 16-bit part, through a delta sigma approach embedded inside the AD SHARC DSP processor, provided the interface and the AD5547 is sufficiently fast.

    This seems indeed like a bit of a problem, which means one may have to throw in a parallel interface afforded by an FPGA or the Analog Devices SHARC DSP processor w the mega-who-knows-what linear-phase-? frijoles-burrito digital filter thingy.

    Awesome stuff Jason! :)
     
    Last edited: Oct 5, 2015
  15. lm4der

    lm4der A very good sport - Friend

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    I haven't had any luck with the 1.03 drivers direct to the machine's usb. However in my case, the Bifrost really does not seem to like my machine's usb ports. Just inserting an _unpowered_ usb hub in between makes the Bifrost Multibit happy.

    Seems like Bifrost Multibit is rather touchy w/regard to USB impl.

    Edit: clarification of first sentence.
     
    Last edited: Oct 5, 2015
  16. Tuco1965

    Tuco1965 Suffring from early onset Alzheimer's - Friend

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    I wonder how my W10 laptop will deal with the upgraded Bifrost given that it was already recognized in its current state?
     
  17. lm4der

    lm4der A very good sport - Friend

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    I think that's probably a good sign. Also, if you already have a Gen 2 usb board in your Bifrost I would think that wouldn't change.

    As another point of reference, my older HP Win7 laptop (like 5 years old), had no problem direct to the laptop's usb. Also, in all cases it finds a driver on Windows Update that works, so I actually don't think there is a need anymore to download the drivers from Schiit - the Windows Update drivers are from CMedia and work fine as far as I can tell.
     
  18. Tuco1965

    Tuco1965 Suffring from early onset Alzheimer's - Friend

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    Yeah I was thinking I should be good since it's already installed. Just didn't know if the Bifrost Multibit upgrade altered anything in that regard.
     
  19. schiit

    schiit SchiitHead

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    What's confusing is this is the same Gen 2 implementation as in tens of thousands of other products--no difference. I suspect it's Microsoft's new handling of the driver (apparently C-Media is talking to them if it's now an automatic download, coupled to draconian USB port power management. Are all of the port power management options turned off on your machines?
     
  20. Huhnkopf

    Huhnkopf Friend

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    Hey marv,

    can you give a bit more insight into point 2? Why does this filter achieve above positives? What's the reason for it? Isn't upsampling often used to "smoothen" out the sound as in less glare, roughness? What do you lose with it?

    Oh, and does it also apply to the Gungnir Multibit? Sure I could test it myself but being weeks away from my own sample (and not having anything good at the moment) I'd rather ask you.
     

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