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Review and Measurements of WesionTEK Khadas Tone Board DAC

mahirzukic2

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These questions are not noobish and are hardly ignorant, in fact they are quite good questions. I will let someone who has read the schematics more than me answer this question.
 

Marvin

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There is no OPA1612 on the board. The output stage consists of 100% NDA (no datasheet or specifications available) opamps that are produced by ESS and sold as part of a complete ES9038Q2M DAC design. In essence this is implemented on the Khadas board with really great PCB design to complement the ESS design.

The parts are as the schematic calls them RT6862D and RT6863.

Seen here:
f76BHjS.jpg


Yellow box is the ES9038Q2M DAC chip itself. Red cube is the output stage opamps.
 

Reyer

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Well, that explains a lot why I couldn't find them on any picture. I've found them listed in description of an ebay auction. Weird.
Thanks for explanation \o
 
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maxxevv

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My KTB has been on order and in the mail for a month and its still nowhere in sight .... Usually I get my stuff delivered within 2~3 weeks max (using free shipping) from Aliexpress.

The official Khadas store hasn't been helpful either. Getting really annoyed.
 

ngs428

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My KTB has been on order and in the mail for a month and its still nowhere in sight .... Usually I get my stuff delivered within 2~3 weeks max (using free shipping) from Aliexpress.

The official Khadas store hasn't been helpful either. Getting really annoyed.

Do you have tracking on the shipment? Are you in the US?
 

maxxevv

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Tracking hasn't moved in 3 weeks. Transport even by ship doesn't take 3 weeks to get to me, I have actually purchased some stuff on Taobao.com that were big enough to use ship cargo via a different forwarder and it was delivered to me in 3 weeks flat!

No I'm not in the US.

Usually I get my stuff from Aliexpress within 2~3 weeks maximum. On good runs, I have received items using "Standard Shipping" in 6 days!
This is tethering on the edge of lost shipments in my experience.
 

gvl

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Mini-Poll. I know the man showed us the graphs.... But does anyone else think the TB is shrill at times? Listening through JDS Labs Atom/HD6XX I can barely handle some tracks. It is very clean, but ear drum piercing at the same time. Speaking of the ESS sound signature... Or is it just bad mastering?
 
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March Audio

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There is no OPA1612 on the board. The output stage consists of 100% NDA (no datasheet or specifications available) opamps that are produced by ESS and sold as part of a complete ES9038Q2M DAC design. In essence this is implemented on the Khadas board with really great PCB design to complement the ESS design.

The parts are as the schematic calls them RT6862D and RT6863.

Seen here:
f76BHjS.jpg


Yellow box is the ES9038Q2M DAC chip itself. Red cube is the output stage opamps.

Rest assured the spec and performance of those op amps is excellent ;)
 

March Audio

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Yeah, but I would like to craft something like that myself. Mostly because I want to learn something totally new and put RPI into use already.

Out of curiocity I have a few more questions that will allow me to understand a bit of how does the op-amps and circuits on DACs work. Please don't get angry, I do understand that they may be outrageously ignorant:

I've read somewhere that the board is equipped with OPA1612. Where are they located?
Since they're most like soldered to the board, would it be okay to unsolder them and swap with some other op-amps? Would it break the board or impair its awesome performance?
Would be there any point in changing them if the board itself is almost perfect?
Would it be possible to add an op-amp socket that would make op-amps swapping more convenient or it would only increase noise in signal or increase the resistance of a circuit that would negatively impact the sound?

In a word, dont :)

Firstly the size of the SMD components makes it a very, very difficult job to replace them. Secondly you will not achieve an significant improvement in technical performance or sound quality - it might well even be degraded.

Amir has a test somewhere on opamp rolling. Im afraid that most that indulge in this sport do not have the technical equipment to make measurements to see if there is any performance change, and then proceed to perform un-controlled listening tests which draw almost certainly faulty conclusions.
 

bequietjk

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Tracking hasn't moved in 3 weeks. Transport even by ship doesn't take 3 weeks to get to me, I have actually purchased some stuff on Taobao.com that were big enough to use ship cargo via a different forwarder and it was delivered to me in 3 weeks flat!

No I'm not in the US.

Usually I get my stuff from Aliexpress within 2~3 weeks maximum. On good runs, I have received items using "Standard Shipping" in 6 days!
This is tethering on the edge of lost shipments in my experience.

Mine took a few weeks ordered straight from Khadas' website.
 

mahirzukic2

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My KTB has been on order and in the mail for a month and its still nowhere in sight .... Usually I get my stuff delivered within 2~3 weeks max (using free shipping) from Aliexpress.

The official Khadas store hasn't been helpful either. Getting really annoyed.
I have ordered the Khadas Tone Board on 17th of December, almost 2 months now. Still nowhere in sight. I am considering (most likely) filing a claim on paypal if it doesn't arive on the 2 month mark (17th of February).
 

soundwave76

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^ same here, it's been a while. Too long soon.

Was there a Khadas representative on these forums?
 

trl

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@hetzer opened up a thread about this opamp https://www.audiosciencereview.com/forum/index.php?threads/new-face-in-op-amp-industry.6058/, in case anyone's interested.

https://dl.khadas.com/Hardware/ToneBoard/Schematic/Tone_V13 SCH.pdf - schematic, scroll down to last page, then zoom in to see the two opamps: RT6862D DFN8 and RT6863 DFN10.

So yes, the 2nd opamp is having 10-pins, so quite difficult to find one to replace it (not even know with what 10-pin opamp). It looks like an output buffer, but I'm not sure I understand what L+/ L-, R+/R- means, given the DACL/DACLB, DACR/DACRB annotation from the DAC chip. I see that its outputs are connected in parallel with the outputs from the first two dual opamps, so is it a DC-servo maybe? Perhaps @Ben1987 could explain what this chip is about and why is it needed inside Khadas? Thank you!

RT6863-DFN10.png

It's not the first time when manufacturers starts testing new components in Asia, not sure it's a marketing strategy or not (I remember ESS did this with a voltage regulator recently).
 

Marvin

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The schematic makes more sense when it's drawn out and not split to pieces. The official schematic is "a professional view" and one has to follow the singal markings.

Sorry for the crudeness, but here is my quick redraw of it with only the interesting components marked (and signal names to match the official schematic) but you can trace it out on the official schematic to see the resistor/capacitor values.

BYgV885.png
 
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alashikata

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Thanks everyone. I got the driver figure out that works perfect now
Whenever you upgraded FW, you may end up with evaluation driver. So make sure you do uninstall and check the box (Delete driver) then run the Setup from this file Thesycon-Stereo-USB-Audio-Driver-V224.rar
Note: Do not run searching driver in the folder but run the setup
Thesycon-Stereo-USB-Audio-Driver-V224.rar

The DSD sounds better than FLAC/MP3. When I compared to the SACD from disc, I didn't hear any different. That's awesome. I can rip my SACD discs to iso to play on computer.
 

alashikata

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I'm using this driver with a different XMOS-based DAC and you're right about Windows settings, in Control Panel > Sound there's a max of 24/192 setting available. With the default Win10 drivers I guess more bitrate is available.

Source files: http://www.msbtechnology.com/faq/bit-perfect-test-files/, http://www.2l.no/hires/ etc.

The 2-XMOS XS-U8 DJ (EVL) driver shows 32 bit 192000 Hz but not the office version. But I will check again tonight to make sure. Because I played from different devices. I remembered I saw 32 bit on laptop when I got Eval version but last night when I configured on desktop, it shows 24 bit. Will double check again to make sure.

Yep, should be same data :D

The bad part is can't play some 5.1 SACD lol which still need to play from SACD player
 

RedCometZero

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Without reading back through the last 20 pages here, what is the advantage to upgrading the firmware of the Tone Board? I can't find update notes on their website. My tone board is on stock firmware right now.
 

gvl

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Without reading back through the last 20 pages here, what is the advantage to upgrading the firmware of the Tone Board? I can't find update notes on their website. My tone board is on stock firmware right now.

You get a nice Trojan tacked onto one of the files. Oh wait, haven't they fixed it already?
 
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