Schiit Modi MB firmware v2 update technical measurements

Discussion in 'Source Measurements' started by atomicbob, Jul 9, 2018.

  1. atomicbob

    atomicbob dScope Yoda

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    If you are unfamiliar with audio measurements please use a search engine with the query:
    "audio measurements" or "audio measurement handbook"
    Look for publications by Richard C. Cabot and also by Bob Metzler, both from Audio Precision. There are other useful publications as well. These will provide basic knowledge.
    Interpretation of the following measurements is beyond the scope of this post.

    The data presented were acquired as follows:

    1. PrismSound dScope III, picoscope 5243B
    2. DAC balanced (Bal) output XLR and unbalanced (SE) output RCA
    3. 100 Kohm load used for measurements
    4. dScope analyzer sample rate 48 KHz unless otherwise noted
    5. DAC 44.1 KHz sample rate, 24 bit depth unless otherwise noted
    6. USB cables – Schiit Pyst and Audioquest Forest
    7. SPDIF input - Tecnec 75 ohm SMPTE 259M/292M Digital Broadcast Cable
    8. Unbalance RCA cable - Worlds Best Cable Gotham GAC-2 or DH Labs Silver Sonic Air Matrix
    9. Balanced XLR cable - Canare L-4E6S starquad with Neutrik XLR connectors
    10. Vaunix Lab Brick USB hub
    11. Shielded 14AWG and 16AWG power cables


    Schiit Modi MB firmware v2 (updated from v1)
    Modi MB - AD5547CRUZ resistor multibit 16 bit resolution DAC
    Measurements commenced after 100 hours of warmup post installing upgrade firmware IC.
    Measurements were performed over a period of 8 hours.

    Modi MB v1 firmware measurements may be found here

    Notable highlights:
    The glitch in V1 firmware previously visible at -70 dBFS is gone in V2. -90 dBFS now renders a sine.
    While V1 Gain Linearity was previously quite good for a 16 bit multiplying multibit architecture DAC,
    with V2 Schiit has set another new standard for this type of 16 bit DAC. Well done @schiit !


    WARNING - PERSONAL OPINION FOLLOWS:
    Whether either the glitch at -70 dBFS or gain linearity deviation below -70 dBFS in V1 was audible to most of the listening population is highly debatable in my opinion. However, the improvement in blackground is welcome.

    Setup picture:
    Modi MB v2 firmware small.jpg

    Index
    Post 1 - measurement setup description, highlights
    Post 1 - SPDIF input - SE outputs part A
    Post 2 - SPDIF input - SE outputs part B
    Post 3 - SPDIF input - SE outputs 1 KHz resolution series, J-Test, residual noise


    SPDIF input unbalanced output measurements part A

    THD and THD+N Spectrum
    20180708-01 Modi MB SE THD THD+N spectrum - spdif.PNG

    THD and THD+N vs Frequency
    20180708-02 Modi MB SE THD THD+N vs frequency - spdif.png

    THD and THD+N vs amplitude at 1 KHz
    20180708-03 Modi MB SE THD THD+N vs amplitude - spdif.PNG

    IMD spectrum
    20180708-04 Modi MB SE IMD spectrum - spdif.PNG

    IMD vs ampitude
    20180708-05 Modi MB SE IMD vs amplitude - spdif.PNG

    Frequency Response
    20180708-06 Modi MB SE FR - spdif.PNG

    Frequency Response (y-axis zoom)
    20180708-07 Modi MB SE FR Y axis highly zoomed - spdif.PNG

    Inferred Jitter
    20180708-09 Modi MB SE inferred jitter - 7 KHz BW - spdif.PNG

    1 KHz gain linearity
    20180708-12 Modi MB SE 1 KHz gain linearity + bandpass - spdif.png
    Very impressive Gain Linearity for a 16 bit multiplying multibit DAC architecture. Well done Schiit!

     
    Last edited: Jul 9, 2018
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  2. atomicbob

    atomicbob dScope Yoda

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    SPDIF input unbalanced output measurements part B

    Imaging
    20180708-13 Modi MB SE imaging - spdif.PNG

    Dynamic Range
    20180708-14 Modi MB SE dynamic range - spdif.PNG

    Crosstalk
    20180708-15 Modi MB SE crosstalk - spdif.PNG

    1 KHz 0 dBu THD+N THD and spectrum
    20180708-26 Modi MB SE 1 KHz THD+N THD FFT 0dBu.png

    50 Hz + 7000 Hz dual tone
    20180708-16 Modi MB SE 50+7000Hz dual tone 3 dBu - spdif.png

    600 Hz + 1700 Hz dual tone
    20180708-17 Modi MB SE 600+1700Hz dual tone 3 dBu - spdif.png


    1kHz @ -90dBFS
    20180708-18 Modi MB SE 1 KHz -90 dBFS - spdif.PNG

    1kHz @ -70dBFS
    20180708-19 Modi MB SE 1 KHz -70 dBFS - spdif.PNG

    20 Hz square wave -3 dBFS 4Vpp 10mS/div
    20180708-23 Modi MB SE 20 Hz sqr -3 dBFS 4 Vpp 10mS div - spdif.PNG

    20 Hz square wave -3 dBFS 4Vpp 100uS/div

    20180708-25 Modi MB SE 20 Hz sqr -3 dBFS 4 Vpp 100uS div - spdif.PNG
     
    Last edited: Jul 9, 2018
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  3. atomicbob

    atomicbob dScope Yoda

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    SPDIF input unbalanced outputs 1 KHz resolution - DAC equivalent of the limbo - how low can you go

    -100 dBFS
    20180708-27 Modi MB SE 1 KHz -100 dBFS - spdif.PNG

    -120 dBFS
    20180708-28 Modi MB SE 1 KHz -120 dBFS - spdif.PNG

    -130 dBFS
    20180708-29 Modi MB SE 1 KHz -130 dBFS - spdif.PNG

    -140 dBFS
    20180708-30a Modi MB SE 1 KHz -140 dBFS - spdif.PNG
    Remember, this is a 16 bit multiplying multibit DAC. Damn, that's impressive. Well done Schiit!

    J-Test
    20180708-41 Modi MB SE J-Test - 7 KHz BW - spdif.PNG
    Not quite the noise floor of Gungnir MB and Yggdrasil but still very impressive for a 16 bit DAC.

    Residual noise and interference
    20180709-60 Modi MB SE noise and interference - spdif.PNG
    The highest component is at the lowest frequency, 60 Hz mains. This plays to the Fletcher-Munson curve response of the Human Auditory System. Very good design trade-off. Outside of the power mains components, the remainder of the spectrum is clean and even.

     
    Last edited: Jul 9, 2018
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  4. atomicbob

    atomicbob dScope Yoda

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    reserved 4/4.
     
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  5. Elnrik

    Elnrik Super Friendly

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    Thanks for your work @atomicbob!

    Are you aware of when V2 firmware started shipping? I ask because I don't know if this is a new development, or something that happened a while back.

    Thanks again!
     
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  6. atomicbob

    atomicbob dScope Yoda

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    I don't know. I received an 8-pin DIP a while back and Jason suggested I might enjoy the results of the firmware update. I didn't get around to it for several months for reasons that can be found in my profile posts.
     
  7. SVChucko

    SVChucko Rando

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    Wow, nice. I bought my Mimby last November, wonder if it has this FW?

    I would love to see the results of USB input testing, if you find time.
     
  8. atomicbob

    atomicbob dScope Yoda

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    The USB input measurements are substantially similar to those found here with exception that the -70 dBFS , -90 dBFS sine and Gain Linearity look like the spdif input above. To obtain best results use an Eitr for USB to SPDIF DDC to SPDIF input on Modi MB with v2 firmware.
     
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  9. Kernel Kurtz

    Kernel Kurtz Acquaintance

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    Just wondering if the firmware DIP is socketed or soldered (asking is easier than opening mine to look). I know the Modi is not marketed as being upgradable, and I'm sure that will remain a selling feature limited to their higher price point devices, but I'm curious if it is "plug and play" regardless.
     
  10. Cspirou

    Cspirou They call me Sparky

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    Internal pics at schitt.com show that it's socketed
     
  11. Kernel Kurtz

    Kernel Kurtz Acquaintance

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    Thanks!
     

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