Measuring DAC Accuracy

Discussion in 'Source Measurements' started by Marvey, Mar 30, 2017.

  1. Marvey

    Marvey Loves Sex and Records

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    Gumby results for one leg of the differential XLR output. Not as good as the balanced, but looks much better than SE (with the summing circuit), at least for just this measurement.
    Gumby 0.5BAL DNL.png
     
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  2. bazelio

    bazelio Friend

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    Oh that's interesting.... yeah, I simply floated XLR pin 3. Subjectively a few of us felt the end result was at least as good as using the ISOMAX. Both Ron and I were running our rigs that way at the Big Meet.
     
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  3. Marvey

    Marvey Loves Sex and Records

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    Yup. Pin 3 was floated in the measurement above. I would hesitate short circuiting those pins considering how the circuit clips with 600 ohm loads.

    FOR NOOBS: Be cautious if you don't know what you are doing. When in doubt, use SE outputs.
     
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  4. atomicbob

    atomicbob Friend

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    Take what Marvey says very seriously. Some pro audio equipment is designed to handle pin 3 (return of hot / return, pin 2 and pin 3) shorting to ground. Mackie and others design for live SR situations where people that do not know what they are doing are likely to do very bad things to the equipment. But this is really a BAD IDEA in general. Use an isolation transformer or float pin 3, with pin 2 only going to the single ended input. Pin 1 will provide the reference ground. Failure to understand how this works will result in a very high probability of distortion and damage.
     
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  5. bazelio

    bazelio Friend

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    And don't buy an off the shelf cable that "looks right" just because it has XLR on one side and RCA on the other side. You probably have no way of knowing if that cable was constructed properly for this use case, and without a DMM you probably have no way to figure it out.
     
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  6. Marvey

    Marvey Loves Sex and Records

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    Haha. You guys just saved Schiit from dealing with a dozen "warranty" returns.
     
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  7. Azteca

    Azteca Friend

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    Yep. I have cables in my office closet that are for one specific panel in one specific venue. They are labeled extremely clearly and have their own hook they hang from. Don't fry your own gear or anyone else's.
     
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  8. cizx.6

    cizx.6 Just couldn't stay away...

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  9. Psalmanazar

    Psalmanazar Friend

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    Well Schiit makes great DACs and AKM makes the best DS chips (outside of my soft spot for the Wolfson 8741 and maybe the new CS4399 if it can lose the hash).
     
  10. ultrabike

    ultrabike Measurbator - Admin

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    It's a competitive market. I dunno if AKM makes the best DS chips. I think Cirrus has it's fans, as do TI. I personally like TI because Texas, but their shit has been expensive lately and they recently decided to kill a lot of nice through hole parts, while upgrading their SMDs. So maybe I don't like TI that much anymore.

    SMDs make sense from the manufacturability point of view though (pursuing the $ cow), but I'm getting out of topic really quick here. So carry on, nothing to see here.
     
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  11. SSL

    SSL Friend

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    Is that true if they've gone to the chipan-fi darkside?
     
  12. Cspirou

    Cspirou Friend

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    Just noticed this thread.

    Modi 2 has a capacitor coupled output while Modi MB is DC coupled. Don't know how much a capacitor would contribute to bowing but it makes sense.
     

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