Schiit Bifrost MB (loaner program unit) technical measurements

Discussion in 'Source Measurements' started by atomicbob, Nov 21, 2015.

  1. atomicbob

    atomicbob dScope Yoda

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    The data presented were acquired as follows:

    1. PrismSound dScope III, picoscope 5243B
    2. DAC unbalanced output RCA
    3. 100 Kohm load used for measurements
    4. 44.1 KHz sample rate, 24 bit depth
    5. USB input – Audioquest Forest
    6. Toslink input - generic toslink optical cable
    7. Unbalance cable DH Labs Silver Sonic Air Matrix RCA
    8. Vaunix Lab Brick USB hub

    Bifrost MB - AD5547CRUZ resistor multibit 16 bit resolution DAC
    Measurements were performed over a period of 21 to 27 hrs of DAC power on time after arriving at my lab.

    Notable highlights:

    Not surprisingly the measurements for the loaner program unit are substantially similar to my Bifrost MB

    Excellent channel matching, even in the distortion measurements
    Jitter is close, though not quite as excellent, as Gungnir MB
    Listening evaluation to note multibit magic of dimension and depth present
    Incedible performance for a 16 bit resolution DAC

    USB input measurements:

    Frequency Response
    20151120 Bifrost MB SE FR - USB.PNG

    Frequency Response (y-axis zoom)
    20151120 Bifrost MB SE FR y axis highly zoomed - USB.PNG

    Dynamic Range
    20151120 Bifrost MB SE dynamic range - USB.PNG

    THD and THD+N
    20151120 Bifrost MB SE THD THD+N - USB.PNG

    IMD
    20151120 Bifrost MB SE IMD - USB.PNG

    Crosstalk
    20151120 Bifrost MB SE crosstalk - USB.PNG

    Inferred Jitter
    20151120 Bifrost MB SE inferred jitter - USB.PNG

    Inferred Jitter (x axis zoom)
    20151120 Bifrost MB SE inferred jitter - 2KHz BW - USB.PNG

    1kHz @ -70dBFS
    20151120 Bifrost MB SE 1KHz -70 dBFS - USB.PNG

    1kHz @ -90dBFS
    20151120 Bifrost MB SE 1KHz -90 dBFS - USB t2.PNG
     
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  2. atomicbob

    atomicbob dScope Yoda

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    USB measurements part B

    1 kHz gain linearity
    20151120 Bifrost MB SE 1KHz gain linearity - USB.PNG

    Imaging
    20151120 Bifrost MB SE imaging - USB.PNG

    20 Hz square wave 0dBFS 6Vpp 10mS/div
    20151120 Bifrost MB SE 20 Hz sqr 6 Vpp 10mS div - USB.PNG

    20 Hz square wave 0dBFS 6Vpp 500uS/div
    20151120 Bifrost MB SE 20 Hz sqr 6 Vpp 500uS div - USB.PNG

    20 Hz square wave 0dBFS 6Vpp 100uS/div
    20151120 Bifrost MB SE 20 Hz sqr 6 Vpp 100uS div - USB.PNG

    Test setup
    Loaner program unit.jpg
     
    Last edited: Nov 21, 2015
  3. atomicbob

    atomicbob dScope Yoda

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    Toslink input measurements

    Frequency Response
    20151120 Bifrost MB SE FR t3 - toslink.PNG

    Frequency Response (y-axis zoom)
    20151120 Bifrost MB SE FR y axis highly zoomed t3 - toslink.PNG

    Dynamic Range
    20151120 Bifrost MB SE dynamic range - toslink.PNG

    THD and THD+N
    20151120 Bifrost MB SE THD THD+N - toslink.PNG

    IMD
    20151120 Bifrost MB SE IMD - toslink.PNG

    Crosstalk
    20151120 Bifrost MB SE crosstalk - toslink.PNG

    Inferred Jitter
    20151120 Bifrost MB SE inferred jitter - toslink.PNG

    Inferred Jitter (x axis zoom)
    20151120 Bifrost MB SE inferred jitter - 2KHz BW - toslink.PNG

    1kHz @ -70dBFS
    20151120 Bifrost MB SE 1KHz -70 dBFS - toslink.PNG

    1kHz @ -90dBFS
    20151120 Bifrost MB SE 1KHz -90 dBFS - toslink.PNG
     
    Last edited: Nov 21, 2015
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  4. atomicbob

    atomicbob dScope Yoda

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    Toslink measurements part B

    1 kHz gain linearity
    20151120 Bifrost MB SE 1KHz gain linearity - toslink.PNG

    Imaging
    20151120 Bifrost MB SE imaging - toslink.PNG
     
    Last edited: Nov 21, 2015
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  5. atomicbob

    atomicbob dScope Yoda

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    reserved.
     
  6. SSL

    SSL Friend

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    Substantially similar, but some notable differences. In particular, the 20Hz square wave appears to have quite a different shape on the top of that waveform. Also, this unit is missing the spike in the noise floor at 2.3kHz. The inferred jitter measurement also appears to be missing those little bumps on either side here as well.

    Measuring variation, expected manufacturing variance, or...?
     
  7. atomicbob

    atomicbob dScope Yoda

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    The 20 KHz square waves for my personal BiMB were captured with a 0 dBFS square wave source. The overshoot is saturating the DAC output stage. I can demonstrate that my personal DAC will look substantially similar when measured at -1 dBFS as I did with the loaner BiMB so the overshoot is completely visible.

    The spike in the noise floor at 2.3 KHz may be due to an issue with my BiMB. When resolved I will measure again. Those little side lobes in the jitter measurement are from the same issue. The Loaner BiMB is more representative of typical performance.
     
  8. SSL

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    Good to know, thanks for clearing that up!
     
  9. Cspirou

    Cspirou They call me Sparky

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    Can you explain what the imaging plot means?
     
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  10. atomicbob

    atomicbob dScope Yoda

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    Imaging is any out of band signals above the filter cutoff frequency, in this case, above 22 KHz. You also can see the roll off of the DAC low pass anti-aliasing (anti-imaging) filter.
     
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