Massdrop x ZDT Jr. Measurements

Discussion in 'Headphone Amplifier Measurements' started by purr1n, Nov 18, 2017.

  1. purr1n

    purr1n Desire for betterer is endless.

    Staff Member Pyrate BWC
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    Load is 330ohm resistor (HD600 and H650 nominal are 300 ohms). A /10 differential probe was used, so voltage is 0.550. This is the same reference voltage I've been using. 0.550V is very darn loud from the HD650.

    Warning: measurement extremists will be shot and killed. Don't mind the spurs. I moved my gear around so am using the ODAC straight from USB. I usually rely on Wyrd / Modi 2. Mostly interested in the D2, D3, D4, etc. and THD.

    1kHz. 0.14% THD
    ZDR jr 1kHz .550V.png


    Checking bass here. How do the transformers perform in the bass?

    100Hz. 0.19% THD
    ZDR jr 100Hz .550V.png

    50Hz 0.29% THD
    ZDR jr 50Hz .550V.png

    30Hz. THD 0.55%
    ZDR jr 30Hz .550V.png
     
  2. purr1n

    purr1n Desire for betterer is endless.

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    Power spec. Turned it up until I hit 1% distortion and could see the beginnings of clipping (odd harmonics). At the point it hits 1% distortion, things go badly very very quickly. So the 1% distortion is the knee on the curve that sort of gives us an effective power rating.

    Again, this is 1kHz into 330ohms. Voltage is 1.39V at 1% THD. (note /10 divider probe)
    ZDR jr 1kHz clipping.png
     
  3. Cspirou

    Cspirou They call me Sparky

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    Any plans on measuring the low impedance output with a smaller resistor?
     
  4. WNovizar

    WNovizar Facebook Friend

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    Any subjective stream of conscious-style impression?
     
  5. purr1n

    purr1n Desire for betterer is endless.

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  6. purr1n

    purr1n Desire for betterer is endless.

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    Using a 22 ohm resistor, I got 2.75 for the low Z out and 4.75 for the high Z out.

    However, check these measurements out for HD650K.

    Gray: Magni 3
    Yellow: Low Z
    Red: High Z

    Looks the same except for very tiny rolloff.
    ZDT HD650K outputs.png

    And here are the 500Hz square waves
    ZDT sq wave HD650M.png
     
  7. purr1n

    purr1n Desire for betterer is endless.

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    NOTE: The distortion / power measurements above were taken on the low Z output. I should do the same with the high Z outputs.
     
  8. Priidik

    Priidik MOT: Estelon

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    3 or 5 ohms into 300 ohms I would expect the difference to be buried to uncertainty.
    I hoped the high-z out to be much higher.
    At what frequency did you measure?
    It might be interesting to see low end response into low resistance.
     
  9. WNovizar

    WNovizar Facebook Friend

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  10. Cspirou

    Cspirou They call me Sparky

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    And people say tubes add tons of distortion. Those HD 650 curves look pretty damn identical.
     
  11. qetadg

    qetadg New

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    Somehow I am having difficulty comprehending this post...
     

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