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E1DA 9038D performance according to df-metric

solderdude

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That'll change the phase considerably in the lows, assuming the coupling cap is directly at the output.
 
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nagster

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That'll change the phase considerably in the lows, assuming the coupling cap is directly at the output.
The box containing the dummy load was not found. I didn't have time so I gave up.
Is 600ohm ok? If so, I might be able to do it tomorrow.
 

solderdude

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Most folks will load that dongle with something between 16ohm and 50ohm.
600ohm will be too high but arguably is better than 200k or even 10k.
33 ohm (standard value) makes the most sense.
 

ReaderZ

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Most folks will load that dongle with something between 16ohm and 50ohm.
600ohm will be too high but arguably is better than 200k or even 10k.
33 ohm (standard value) makes the most sense.

My HD800s(re-bought) hasn't been plugged into anything besides a dongle yet... Had it for a month or so now.:cool:
 

solderdude

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There are always exceptions. :)
Besides with 600ohm load (and even higher in the bass !) the phase shifts will be much lower than for most users that drive their high efficiency portable headphones with it.
That is... still under the assumption there is a capacitor in the headphone out part (which would make sense).
 

solderdude

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@nagster then in that case no need to bother with more testing.

It does show that a gradual phase shift of 40degrees (-3 dB) @ 2Hz, that arguably is inaudible, has a quite severe effect on nulling and number generation when small and gradual phase shifts is not corrected for in the generation of a single number that is supposed to represent 'audio quality'.
 

nagster

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@nagster then in that case no need to bother with more testing.

It does show that a gradual phase shift of 40degrees (-3 dB) @ 2Hz, that arguably is inaudible, has a quite severe effect on nulling and number generation when small and gradual phase shifts is not corrected for in the generation of a single number that is supposed to represent 'audio quality'.
got it. Well, thanks to that I was able to find the dummy load.
correction. The minimum load value built into the APx was 300ohm, not 600ohm. 300ohm was not in my mind.
 

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pma

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Nulling is a problematic method with respect to audibility. Rather make DBT with 2 files.
 

nagster

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Phase measurement of 9038D.
I don't have a Shanling device.

* All measurements were conducted with AP balanced input (200kohm) and no load.
I was just looking at the settings for the ADI-2 DAC and found that it was set to Ref 13dBu instead of Ref 7dBu.
I can't edit it, so I'll correct it here.
 
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Serge Smirnoff

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I don't know exactly how various phase shifts are perceived by the ear and I also - as many - think that the low-freq phase shift is not too important. But I also know that if we replace all the phases of some music signal with the random ones, we will get just a noise shaped according to a freq content of the initial signal. In other words, audibility of phase errors has its thresholds/limits, should be characterized and hardly researched well with real music.

In this particular case of #9038 there is another source of the degradation and even more significant - time inconsistency of the output signal. And it affects both magnitudes and phases. It is most visible on phase diffrogram with the multi-tone signal [https://audiosciencereview.com/foru...nce-according-to-df-metric.47932/post-1732473]. Here is the distribution of errors (DF,dB) for our two devices with the multi-tone signal (2min, window:50ms):

9038-multi-wf.png

#9038 DFwf(median): -32.37 dB
9038-multi-mg.png

#9038 DFmg(median): -45.49 dB
9038-multi-ph.png

#9038 DFph(median): -34.84 dB
m0-multi-wf.png

M0 DFwf(median): -75.81 dB
m0-multi-mg.png

M0 DFmg(median): -75.58 dB
m0-multi-ph.png

M0 DFph(median): -61.53 dB


The time inconsistency makes the histograms of #9038 wider and significantly worsens the median values. Thanks to that inconsistency/jitter the difference signal is pretty loud in all frequencies and those frequency components are not stable throughout the whole signal.
 

solderdude

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I don't know exactly how various phase shifts are perceived by the ear and I also - as many - think that the low-freq phase shift is not too important. But I also know that if we replace all the phases of some music signal with the random ones, we will get just a noise shaped according to a freq content of the initial signal. In other words, audibility of phase errors has its thresholds/limits, should be characterized and hardly researched well with real music.

But that is not the case here. The phase shift is gradual and not big so inaudible.
What you should do is remove that phase error from the weighing of the 'sound quality' aspect.
Of course substantial and steep phase shifts in the 400Hz to 8kHz range should be included in the weighing.

Jitter (all kinds of jitter) can be measured and shown to exist.
 

solderdude

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Is the 'except the phase error' here the biggest issue of the end result ?
Even if it results in very small magnitude differences that are in perceptible a phase error, when not corrected will appear as a magnitude difference in the null.
 
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Serge Smirnoff

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The magnitude error (DFmg) does not account the “magnitude differences” you mention (caused by the phase errors) because magnitude components of the output signal are not amplified due to the phase errors. For example the magnitude diffrograms of #9038 do not show inaccuracy of low frequencies while the phase diffrograms do [https://audiosciencereview.com/foru...nce-according-to-df-metric.47932/post-1732473]. So, the DFmg measures exclusively the “tonal” mistakes of a DUT.

And the tonal degradation in #9038 is pretty big: -45.5dB vs. -75.6dB for M0. I attribute this inaccuracy to the time inconsistency, which affects both phases and magnitudes, and phases are affected to a greater extent (see the diffrograms with multitone signal).
 
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