Field guide to determining Modi MB or Bifrost MB v1 or v2 firmware

Discussion in 'Source Measurements' started by atomicbob, Jul 16, 2018.

  1. atomicbob

    atomicbob dScope Yoda

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    Field guide to determining Modi MB or Bifrost MB v1 or v2 version firmware

    This procedure requires some DIY ability and willingness to acquire appropriate HW & SW.

    Required:
    1. Soundcard I/O with at least 16 bit A/D input
    2. Digital Scope program

    The Behringer UCA202 $30 US is an inexpensive USB 16 bit A/D and D/A that works well enough for this purpose:
    https://www.amazon.com/BEHRINGER-U-Control-Low-Latency-Interface-Digital/dp/B000KW2YEI


    Christian Zeitnitz created a very useful soundcard oscilloscope that can be found here:
    https://www.zeitnitz.eu/scope_en

    It would be good to give him a virtual beer+inexpensive meal (Soundcard Scope $14 US) as a thank-you:
    http://www.shareit.com/product.html?productid=300341154


    This combination of HW+SW provides a very low cost Signal Generator / Oscilloscope combination. Very useful for continued education and experimentation.

    When using the UCA202 assure that the driver is correctly configured:

    1. select the UCA202 driver
    20180716-01 UCA202 win7 setup device selection.png

    2. levels should be set to 100
    20180716-02 UCA202 win7 setup level.png

    3. default shared mode should be 2 channel, 44 KHz, 16 bit. Verify both boxes are checked.
    20180716-03 UCA202 win7 setup format and mode.png

    Connect DAC outputs to soundcard inputs (monitor switched off):
    IMG_2465_small.jpg


    Soundcard Scope setup:

    1. select appropriate input and output devices
    20180716-01 Soundcard Scope device select.png

    2. adjust signal generator for 440 Hz and amplitude of 0.0000316 (-90 dBFS). After entering this value press Enter key.
    20180716-02 Soundcard Scope sig gen setup.png

    The display will return 0.000. Don't worry. It has been adjusted but doesn't display beyond 3 digits past the decimal point. Remember to enable the signal generator.
    20180716-03 Soundcard Scope sig gen setup display truncation.png


    3. Adjust scope parameters as shown in the screenshot
    1.5m amplitude
    8.0m time base
    normal trigger
    trigger on


    Modi / Bifrost MB with v1 firmware display (no evidence of a sine wave)
    20180716-05 Soundcard Scope v1 firmware.png

    Modi / Bifrost MB with v2 firmware display (sine wave apparent in display)
    20180716-04 Soundcard Scope v2 firmware.png

    In my setup channel 1 was used for a Modi MB DAC with v2 firmware and channel 2 for v1 firmware (separate, additional DAC) so I could capture both simultaneously. I did this for my convenience. Only channel 1 is necessary for determination.



     
    Last edited: Jul 16, 2018
  2. Elnrik

    Elnrik Super Friendly

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    Last edited: Jul 16, 2018
  3. gixxerwimp

    gixxerwimp Professional tricycle rider

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    It would be great if people who have made the determination could post their serial numbers so that those that are unable to have data points with which to extrapolate.
     
  4. kukur9

    kukur9 Rando

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    Sheesh, I keep thinking I can sell my Schiit for a good resale price if needed, but then A2 comes along and now this kind of thing pops up! v2 Firmware?!? I better get my Modi Multibit on HF before everyone there reads this post... Dang. What's next to drive used Schiit prices down? Dimmer LEDs?!? Front-mount power switches? Black finish, standard? The price of progress is killin' me. ;)
     
    Last edited: Jul 17, 2018
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  5. Ash1412

    Ash1412 Friend

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    Thanks @atomicbob. Can you show us your results for the 70db sine? Also, why 440hz instead of 1k like your standard measurements?
     
  6. atomicbob

    atomicbob dScope Yoda

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    The purpose of this test was to provide a low cost method of identifying v1 vs. v2 firmware in either a Modi MB or Bifrost MB. It wasn't meant to be a measurement suite. 440 Hz is the Soundcard Scope signal generator default setting. It also is more pleasant to experience if a speaker or headphone has inadvertently been left enabled. 1KHz is very annoying, stimulating the basilar membrane to a higher level, as can be determined by looking at Fletcher-Munson curves.

    The data you request may be found in these two posts:

    v1 firmware: Schiit Modi MB technical measurements

    v2 firmware: Schiit Modi MB firmware v2 update technical measurements
     
  7. lm4der

    lm4der A very good sport - Friend

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    @atomicbob Does the fact that the v2 firmware shows a sine wave whereas the v1 firmware doesn't indicate that the v2 firmware is doing something better than v1? Can you elaborate on what's going on there?
     
  8. atomicbob

    atomicbob dScope Yoda

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    The answer to your questions may be found in the Notable Highlights in this post:
    Schiit Modi MB firmware v2 update technical measurements
     
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  9. purr1n

    purr1n Finding his inner redneck

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    -90db is flipping the two LSBs up and down, so with 16 bit content, we are not going to really see a sine wave anyway, but in theory just a step up and a step down. Nothing is perfect, so we will see random noise, ripple, and glitch. The v1 had a lot of glitch and ripple from that, so there pretty much wasn't anything resembing a signal. The v2 gets rid of the glitch and seems to add dither, a randomish wavering of the signal so it looks more like a curved sine. (Think dither in GIF images limited palette.)
     
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  10. atomicbob

    atomicbob dScope Yoda

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    Here is a link that has a reasonably high level explanation including the images analogy visualized:
    http://darkroommastering.com/blog/dithering-explained

    Also keep in mind that for this purpose, the UCA202 has a 16 bit D-S A/D with corresponding anti-aliasing filter which further degrades actual fidelity. But the UCA202 is good enough to make a discrimination between versions and is cheap.
     
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  11. gixxerwimp

    gixxerwimp Professional tricycle rider

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    So I took a whack at this, but the results are a bit inconclusive, probably due to my setup.

    My PC has a Realtek ALC888 audio codec with ADCs that support 16/20/24-bit PCM. I didn't have an RCA > 3.5mm adapter, so I made one like this.

    20180718_214824.jpg

    I followed Bob's instructions and got the following:

    Amplitude: 0.0000316
    Modi 0.0000316.jpg

    The sine wave wasn't as clear as Bob's v2, so I increased the amplitude to see what would happen.

    Amplitude: 0.000050 (a bit better)
    Modi 0.00005.jpg

    Amplitude: 0.000080 (looks kinda like Bob's v2)
    Modi 0.00008.jpg

    Amplitude: 0.000100
    Modi 0.00010.jpg


    I wonder if the input signal is being attenuated, as my amplitude is lower than Bob's, and this is what the recording controls look like:
    Recording Controls.jpg

    "Recording" level is maxed, but Mic and Line Volume are at about 75% and I can't change them. I'm using Line In for input.

    I also measured my Micro iDSD (Silver) and got this:

    Amplitude: 0.0000316
    Micro iDSDa.jpg

    Looks like a hint of sinusoidal, maybe.
     
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  12. atomicbob

    atomicbob dScope Yoda

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    @gixxerwimp : your adapter isn't up to the task. 0 dBFS for Modi MB is 2Vrms. -90 dBFS is approximately 63.25 uVrms. 63 millionths of a volt. Shielding must be maintained end to end to avoid introduction of noise from external sources. You have significant noise in your measurement. If you are using a laptop or PC internal line input A/D there may be additional opportunities for noise contamination.

    You need one of these:
    https://www.amazon.com/C2G-Cables-40645-Adapter-Compliant/dp/B000J1H4VI/

    props for attempting this.
     
    Last edited: Jul 18, 2018
  13. gixxerwimp

    gixxerwimp Professional tricycle rider

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    Yeah, I figured as much. I used to have one of those adapters but I cannabalized it for something. HW store across the street only had that 2-into-1 3.5mm dealio. I'll pick up the right one and try it again.
     
  14. gixxerwimp

    gixxerwimp Professional tricycle rider

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    I bought an RCA > 3.5mm cable and tried it again, but the results are pretty much the same. So I guess the limitation in my setup is the internal line input A/D of my PC.
    Oh well ... :drunk:
     
  15. atomicbob

    atomicbob dScope Yoda

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    Ok, let's work with the first measurement you documented at -90 dBFS (gen at 0.0000316).
    Look at the repetitive bursts. They are similar to the ones in the v1 firmware I've posted. Additionally, the sinusoidal baseline in your measurement at that low level appear to have a period of 5.5 mS which is consistent with 180 Hz mains noise. So if your Modi MB is more than several months old, I'd venture it is v1 firmware.

    Modi MB v1 at -90 dBFS
    20180716-05 Soundcard Scope v1 firmware - annotated.png

    @gixxerwimp Modi MB at -90 dBFS
    Modi 0_0000316 - annotated.png

    props again to @gixxerwimp for diagnostic work.
     
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  16. Kernel Kurtz

    Kernel Kurtz Friend

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    I already know my Modi Multibit is a V1, but that software certainly looks interesting. I think I'll give this a try just for fun.
     
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  17. Elnrik

    Elnrik Super Friendly

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    The UCA222 arrived. Took no time to get it setup.

    My results are a bit more fuzzy than @atomicbob's. I'm thinking V2.

    Scope.png

    Scope2.png

    If anyone wants to borrow this device, let me know. Just pay shipping.

    IMG_20180719_094933.jpg

     
    Last edited: Jul 19, 2018
  18. Ash1412

    Ash1412 Friend

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    How bout running it at -70db and looking for the glitch? Thats assuming the glitch fix came with the dithering update.
     
  19. Ash1412

    Ash1412 Friend

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  20. Elnrik

    Elnrik Super Friendly

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    Sure, what's the amplitude setting for that on the signal generator?

    It's connected via USB, yes.
     

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