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Review and Measurements of WesionTEK Khadas Tone Board DAC

amirm

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#1
This is a review and detailed measurements of Khadas Tone Board DAC from WesionTEK. It is on kind loan from the company. The retail price on Amazon is USD $99 including free shipping.

As the name indicates, this is a bare board DAC:

Kodas Tone Board DAC Review and Measurement.jpg

Don't confuse this with Raspberry Pi boards though. This is a complete DAC and doesn't need a host to operate. It is just like any other desktop DAC except that it doesn't come with a case.

The Khadas Tone Board is powered and accessed through the USB port and S/PDIF. For my review, I only tested the USB input.

Output as you see is through a pair of RCA jacks that have a great high-quality look and feel (as does the S/PDIF one). It would be at home in DACs at much higher prices.

WesionTEK sells two versions of this board, one of which mates with their host processor to make a complete networked DAC and player. They were kind enough to send me the host which I will review later.

Let's get into measurements and see how well it does.

Measurements
As usual, we start with our dashboard view:
Khadas Tone Board DAC Dashboard Measurement.png


I must say, I was not prepared for such excellent performance from such an unassuming board! Essentially 110 dB SINAD (signal above noise and distortion) in a $99 DAC? That is most excellent:
Khadas Tone Board DAC Sinad Measurement.png


I should have of course paid attention to the web page for this product: http://szwesion.com/khadas-tone-board/

Right there is the same dashboard measurement with the same Audio Precision APx555 analyzer I have with identical response!



Their THD+N is 0.000337% and mine is 0.000331%. Wow, what consistency!!!

This is a company that does things right, measuring and verifying designs.

Continuing on with jitter and noise we get:

Khadas Tone Board DAC jitter and noise Measurement.png


There a lot of little spikes visible but that is partly due to very low noise floor which reveals more of these. Worst case spike is below -130 dBFS which is well below any threshold of audibility.

Here is intermodulation distortion versus level:
Khadas Tone Board DAC Intermodulation Measurement.png


Here, we have typical response similar to what we get from other desktop DACs using ESS' later DAC chips.

Dynamic Range comes next:
Khadas Tone Board DAC Dynamic Range Measurement.png


This is very good but a bit shy of their numbers. This measurement though is very sensitive to such things as ground loop so in other situations it may be possible to get close to the 120 dB number they post.

I have been asked for crosstalk measurements so here it is:

Khadas Tone Board DAC Channel Seperation Crosstalk Measurement.png


The spec better than 127 dB and it definitely seems to be there at almost all frequencies.

Crosstalk usually increases with frequency as we see in Schiit Modi 3 graph but here, the Khadas Tone Board maintains the same level throughout audio band which is excellent.

Lastly, we have linearity test:

Khadas Tone Board DAC Linearity Measurement.png


I like to see less than 0.5 dB of deviation at -120 and Khadas Tone Board easily sails through that criteria.

Conclusions
WesionTEK contacted me and joined the forum immediately after someone mentioned this board as something to test. They quickly sent me the samples but due to my busy schedule, I was remiss in not testing it until now. I regret that delay seeing how well their product did in my testing.

The Khadas Tone Board is a high performance DAC and a bargain price. It is exceptionally well engineered and easily earns my highest recommendation!

Get your own case for it and tell your friends you designed it. :)

That WesionTEK is active on forums and ready to support their owners is a fantastic bonus.
 

gvl

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#4
I should look it up, but any idea what those headers are for? Is there a differential hookup?
 

Sythrix

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#8
I just want to know where the ESS hump comes from. It’s just weird behavior and it’s in every design utilizing their chips.
 

amirm

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#9
I just want to know where the ESS hump comes from. It’s just weird behavior and it’s in every design utilizing their chips.
I sent email to their marketing director and he never responded.

I don't think anyone has put magnifier glass on this issue until we started to measure it. Hopefully over time they take notice and do something about it.
 

gvl

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#10
Benchmark doesn't have this problem, right? I thought they mentioned there are usually common mode irregularities on the output of the DAC chip, proper CMR downstream of the chip takes care of it. That's what they said anyway.
 

restorer-john

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#11
That's an impressive performance from a tiny little board. Are you going do any testing via SPDIF?

The SPDIF socket silk screen appears to say in/out too...
 

Veri

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#12
I sent email to their marketing director and he never responded.

I don't think anyone has put magnifier glass on this issue until we started to measure it. Hopefully over time they take notice and do something about it.
I always thought it was their 'thd compensation' and thus basically 'expected' behavior.
 

Veri

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#13
Benchmark doesn't have this problem, right? I thought they mentioned there are usually common mode irregularities on the output of the DAC chip, proper CMR downstream of the chip takes care of it. That's what they said anyway.
Didn't Benchmark use the 9028 instead of the 9038?
 

Sythrix

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#14
Benchmark doesn't have this problem, right? I thought they mentioned there are usually common mode irregularities on the output of the DAC chip, proper CMR downstream of the chip takes care of it. That's what they said anyway.
The DAC 3 doesn’t, it would seem.
 

Sythrix

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#15

gvl

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#16
Looks like SPDIF output is only available on the board that mates with the external processor.

What I want to know if they supply a legit XMOS driver for the USB input. I'm still on W7 and don't get UAC2 for free.
 

Sythrix

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#18
...and it’s in every design utilizing their chips.
So I am wrong? It’s only in 9038? Or were there any others that had it?

I remember now. So is the consensus the hump is a 9038 "feature"?
That’s what the evidence seems to suggest, unless someone knows of a case that proves otherwise... nothing like working backwards on your successive designs! :p
 

wadec22

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#19
Are there many case options for something like this? Quick Google search doesn't return much other than their own DIY case that doesn't appear to be really made for the tone board.
 
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