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Review and Measurements of WesionTEK Khadas Tone Board DAC

matgir99

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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:


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:
View attachment 16340

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:
View attachment 16341

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:

View attachment 16342

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:
View attachment 16343

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

Dynamic Range comes next:
View attachment 16344

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:

View attachment 16345

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:

View attachment 16347

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.
Am I the only one using the khadas tone board also as amplifier directly for my IEMs?
 

Veri

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Am I the only one using the khadas tone board also as amplifier directly for my IEMs?
Considering it is not built for this, the impedance output of the DAC will have unexpected effects on the frequency response.
It's not really recommended. I'm sure noise-wise it will be not a problem, but FR-wise... not the best idea!
 

g29

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Considering it is not built for this, the impedance output of the DAC will have unexpected effects on the frequency response.
It's not really recommended. I'm sure noise-wise it will be not a problem, but FR-wise... not the best idea!
FWIW: Khadas sells this optional adapter cable for an additional cost.

Connect your Tone Board's RCA stereo output to a 3.5mm compatible set of speakers or headphones.

Compatibility:
  • Khadas Tone Board
  • Audio Equipment w/ RCA Output
  • Headphones or Speakers with 3.5mm Male Audio-Jack
RCA to 3.5mm cable


 

zermak

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@g29
If I recall looking at the Kahdas TB schematics the impedenceof the RCA outputs is 100 Ohm very high impoedence to get a flat FR with IEMs and their low impedence. I suggest you to use a amp with low output impedence to enjoy the music with your IEMs.
 

g29

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@g29
If I recall looking at the Kahdas TB schematics the impedenceof the RCA outputs is 100 Ohm very high impoedence to get a flat FR with IEMs and their low impedence. I suggest you to use a amp with low output impedence to enjoy the music with your IEMs.
Mine goes straight into an electronic XO. No earbuds or headphones.
 

Veri

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FWIW: Khadas sells this optional adapter cable for an additional cost.

Connect your Tone Board's RCA stereo output to a 3.5mm compatible set of speakers or headphones.

Compatibility:
  • Khadas Tone Board
  • Audio Equipment w/ RCA Output
  • Headphones or Speakers with 3.5mm Male Audio-Jack
RCA to 3.5mm cable


As said, this doesn't change anything about the 100ohm output. Still wouldn't do it.
 

g29

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Hi,
I connected the J3 FPC 30PIN to ESS Controller from Ian from diyaudio.com,
and now I can control any registers of ES9038Q2M. View attachment 34763
Very cool. Thanks for sharing.

From page 6, it looks like only 6 "signals" are used.
  • 5V
  • GND
  • I2C CL
  • I2C DA
  • LRCK/D1
  • SCK

Ian’s ESS controller user ’s guide
KTBD Manual

Update:

Looks like 10 wires (5 grounds) can be soldered to the 10 through hole mounts on the back of the controller/display and then soldered to a 30 Pin FPC to DIP breakout board. The ribbon cable then completes the connection between the controller/display and the KTBD.


 
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Very cool. Thanks for sharing.

From page 6, it looks like only 6 "signals" are used.
  • GND
  • I2C DA
  • 5V
  • SCK
  • LRCK/D1
  • I2C CL

Ian’s ESS controller user ’s guide
Yes exactly.

Looks like 10 wires (5 grounds) can be soldered to the 10 through hole mounts on the back of the controller/display and then soldered to a 30 Pin FPC to DIP breakout board. The ribbon cable then completes the connection between the controller/display and the KTBD.
You can connect to J3 10pin or to J1 40pin.
 
Last edited:

g29

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Yes exactly.

You can connect to J3 10pin or to J1 40pin.
Have you noticed any anomalies using Ian's ESS Controller ?

Do all of the features/menu options/displays work with the KTBD ?

Did you diverge from the factory default settings/filter selections ?

TIA
 
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Have you noticed any anomalies using Ian's ESS Controller ?
Everything looks good to me...

Do all of the features/menu options/displays work with the KTBD ?
Everything seems to be working as in the ESS Controller manual, some functions are not for ESS9038Q2M (like IIR filter Bandwidth, FIR filter shape).

Did you diverge from the factory default settings/filter selections ?
Yes, but I didn't spend much time on it, I focused on launching and functional testing of all functions by connecting KTBD to a laptop.
Now I have to connect to a better source than a laptop, maybe I will have to add a separate power supply to KTBD. We'll see ...
 

maxxevv

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This has certainly piqued my interest for the KTB add-on. Think it will fit nicely with a case made to match the JDS Atom dimensions !

Time for some research !
 

g29

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...

Yes, but I didn't spend much time on it, I focused on launching and functional testing of all functions by connecting KTBD to a laptop.
Now I have to connect to a better source than a laptop, maybe I will have to add a separate power supply to KTBD. We'll see ...
Thanks for the quick response.

I was wondering if the USB's 5VDC was enough to drive the DAC, ESS Controller and RCA outs by itself.

As for an alternate input source, this Topping D10 S/PDIF Bridge thread maybe of interest, but you will be limited to 192 via S/PDIF.
 
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I was wondering if the USB's 5VDC was enough to drive the DAC, ESS Controller and RCA outs by itself.
KTBD normally is power hungry (specification 5V/500mA). But with laptop work OK, but when connect to eg. Raspberry Pi I have often hangs. And now I must connect to KTBD external power 5V and maybe 1A. I will test...
 
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KTBD normally is power hungry (specification 5V/500mA). But with laptop work OK, but when connect to eg. Raspberry Pi I have often hangs. And now I must connect to KTBD external power 5V and maybe 1A. I will test...
My raspberry 4 with touchscreen and KTB runs without problems on Anker usb charger via good usb cable (amazon basics)
 
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My raspberry 4 with touchscreen and KTB runs without problems on Anker usb charger via good usb cable (amazon basics)
Raspberry 4 is a different USB design than eg. ver. 3B+. It is USB 3.0 (higher current) and separated USB Hub from LAN. And here everything can be OK.
 
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Any evidence if the Tone board suffers from the so called noise floor modulation?
@amirm, can you post the FFT of the board when outputting nothing and a sin at full amplitude?
 
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