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Review and Measurements of WesionTEK Khadas Tone Board DAC

amirm

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#62
@amirm, since this hump is such a common (although not ubiquitous) feature of devices using this ESS chip, I'd find it interesting to see a distortion spectrum in the range of the hump, say at around -25 to -30dB, to compare to the spectrum at 0dBfs.
It took some effort to tease out the same distortion in THD measurements but I finally got there:

1539193706454.png


In normal THD+N vs level it would not show up (or hardly at all). Shows the usefulness of IMD measurements.

As suggested I will write a new article with lots more data and then try to forward that to ESS and see if we get an answer.
 

TimW

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#63
If you're looking for a music player for Android to support USB DAC you're pretty much left only with one choice: USB Audio Player PRO
Would this be used if you're trying to connect a phone to the generic version of the DAC via USB? Or could it run on the Khadas VIM connected to the DAC via GPIO?
 

andreasmaaan

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#64
It took some effort to tease out the same distortion in THD measurements but I finally got there:

View attachment 16369

In normal THD+N vs level it would not show up (or hardly at all). Shows the usefulness of IMD measurements.

As suggested I will write a new article with lots more data and then try to forward that to ESS and see if we get an answer.
Very interesting, thanks for going to the effort :)

I can't recall now which test you use for IMD (I think it was CCIF??), but whichever test it is, would it be possible please to display a spectrum (i.e. frequency on the x-axis, voltage or dB on the y-axis) for IMD at 0dBfs, and another graph with identical axes showing the same at say -30dBfs?

Sorry, this was what I was trying to get at with my previous post. Obviously wasn't clear enough about it!

A
 

Krunok

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#65
Would this be used if you're trying to connect a phone to the generic version of the DAC via USB? Or could it run on the Khadas VIM connected to the DAC via GPIO?
Not sure if it would work via GPIO but it would certainly work when connected with USB to any Android device. I see no reason to connect it to Khadas VIM via USB as well, in that scenario it should work as well.
 

amirm

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#66
Very interesting, thanks for going to the effort :)

I can't recall now which test you use for IMD (I think it was CCIF??), but whichever test it is, would it be possible please to display a spectrum (i.e. frequency on the x-axis, voltage or dB on the y-axis) for IMD at 0dBfs, and another graph with identical axes showing the same at say -30dBfs?
Let's have the discussion in the article I will write. For now, here are two sample points (-30 and -40 dBFS) for the SMPTE IMD spectrum:

1539194952817.png


Noise floor does not change but we get a lot more intermodulation distortion (in blue).
 

gvl

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#67
Here is the S/PDIF input performance. You activate it by just hooking up a USB power supply to USB port. I used the little switcher Wesion sent me.

View attachment 16368

With USB input, Channel 2 had some spikes around 10 kHz which are now gone, resulting in nearly 2 dB improvement.
Are you saying we basically have Benchmark DAC3 level of performance at about 1/20 of the cost?
 

amirm

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#68
Are you saying we basically have Benchmark DAC3 level of performance at about 1/20 of the cost?
Not quite. Besides all the other features Benchmark has, it also has better intermodulation distortion.

A better way to say the Khadas is within an inch of perfection for 1/20th of the price. :)
 

andreasmaaan

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#69
Let's have the discussion in the article I will write. For now, here are two sample points (-30 and -40 dBFS) for the SMPTE IMD spectrum:

View attachment 16370

Noise floor does not change but we get a lot more intermodulation distortion (in blue).
Perfect, thanks. This is exactly what I was interested in. Looking forward to the article :)
 

Krunok

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#71
Not quite. Besides all the other features Benchmark has, it also has better intermodulation distortion.

A better way to say the Khadas is within an inch of perfection for 1/20th of the price. :)
It really depends on how you define perfection as that difference in IMD can hardly be hearable.
 

amirm

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#72
Could you also please test jitter with this configuration?
Sure:

1539196940519.png


Other than a tiny mains leakage at -140 dB, it is exceptionally clean!
 

amirm

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#75
I've been thinking about getting an inexpensive reference DAC that I could use as a baseline in my audiophilic experiments. If this ain't it I don't know what is.
I am with you. I don't usually get excited when reviewing gear but I went to bed all happy to have found this DAC!

They tell me they have plans for follow up products. So let's support them by buying some of these boards. You can get an acrylic sheet and drill four holes in it and be in business.
 

pos

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#77
Amir, could you also please test if the unit emits pops/clicks on turn on/off or with spdif sync changes?

Regarding dynamic range, as I understand it the measurement in your original post is mostly influenced by the >20kHz behavior, right?
 

Veri

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#80
This DAC is seriously worth being excited over. Not sure how much of this stellar performance is audible over others, but damn if these graphs aren't sexy ;)
 
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