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Old 19th June 2012, 09:54 AM   #31
repeet is offline repeet  Australia
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New version 1.9
NEW V1.9 DAC WM8741 WM8805 Coaxial Optical Decoder 24Bit kit DIY | eBay
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Old 19th June 2012, 01:14 PM   #32
alkasar is offline alkasar  France
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anyone knows what this means ?
"Version1.9 add the DC servo circuit and the Second LPF circuit is Class A current output. 4 opamps upgrade into 2 opamps"
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Old 19th June 2012, 01:44 PM   #33
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Quote:
Originally Posted by dhalbakken View Post
I recently bought a WEILIANG DAC5 from China.

Click the image to open in full size.

It sounds quite nice to me, but I expected better-looking square wave outputs from the MFSL test CD square wave tracks. I used a Win7-64bit machine and standard Windows drivers to drive the USB input to the Tenor TE7022 board, which, in turn, I think, drives the DAC5 via I2S.

1 KHz square wave as seen on my old 100MHZ Tektronix 454 scope at the phono connector output:

Click the image to open in full size.

and 5KHz square wave:

Click the image to open in full size.

I've never played with DACs before, but I think there must be some problems with this DAC. Can anyone with more familiarity with DACs give me a clue what might cause such distorted wave forms?

Dave
Perhaps, this was already mentioned somewhere in this thread, but the tilt evident in the 1KHz squarewave simply looks like a scope probe calibration issue. The ringing on the tops and bottoms of the waveform is normal, being produced by a linear phase brickwall interpolation filter. The 5kHz squarewave simply looks like the harmonics (everything above the 3rd) have been removed, which they would be by the brickwall filter. The only reason why one would apply a squarewave to a DAC is to view the time domain response, which appear normal in your photos to me. I may be missing something but, I don't see anything wrong with either waveform other than your scope probe may need calibration.
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Last edited by Ken Newton; 19th June 2012 at 01:57 PM.
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Old 5th July 2012, 08:41 AM   #34
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Quote:
Originally Posted by alkasar View Post
anyone knows what this means ?
"Version1.9 add the DC servo circuit and the Second LPF circuit is Class A current output. 4 opamps upgrade into 2 opamps"
I'm quite sure that only one dual op-amp is being used in the new version instead of one dual plus two singles. Maybe something like this:

Click the image to open in full size.

Last edited by dhalbakken; 5th July 2012 at 08:44 AM. Reason: Try to fix image appearance
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Old 5th July 2012, 11:18 AM   #35
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Regarding the interpretation of square wave response I have always found this this site Waveform Analysis to be helpful with the basics. See Fig.1 D
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Old 6th July 2012, 12:54 AM   #36
bcmbob is offline bcmbob  United States
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Hello Folks, I have a problem with a version of this design on the most basic level. I bought this kit from a vendor named good.feedback on eBay. After waiting almost eight weeks the package arrived with most of the resistors missing. They did arrive within a week or so but some still don't match up. It appears today the vendor has basically disappeared before I could get things in order and receive the docs and schematic I requested.

So I'm hoping someone (from the photos) can tell me the correct values (ohm & wattage ) for the missing resistors based on their position and/or adjacent parts. From what I can find there are at least three versions of this DAC and I'm hoping there is enough knowledge around to prevent this project becoming a lost cause.

Thanks in advance.....
Attached Images
File Type: jpg WM1.JPG (129.4 KB, 973 views)
File Type: jpg WM2.JPG (152.5 KB, 188 views)
File Type: jpg WM3.JPG (111.1 KB, 223 views)
File Type: jpg Missing Resistorss.jpg (209.2 KB, 260 views)
File Type: jpg Remainder.jpg (49.0 KB, 225 views)
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Old 6th July 2012, 03:13 AM   #37
erin is offline erin  Australia
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Did you get a schematic with the kit?
You will only need 1/4 watt resistors.
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Old 6th July 2012, 03:17 AM   #38
bcmbob is offline bcmbob  United States
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Great, that's a start. I had asked for the schematic twice and was going to do so again today when I discovered they have most likely folded up shop. I'm going to try the other vendors tomorrow.
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Old 6th July 2012, 06:45 AM   #39
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All the resistors on my board look as if they're 1% metal film 1/8 watt.

Are all the capacitors, semiconductors, etc. missing also, as your photo seems to show?

I suspect this Taobao storefront might be closely associated with Weiliang:

Google Translate

They say they provide tech support, but they didn't respond to me when I sent them an email. If I had written in Chinese instead of English, I might have had better luck.

I can send you hi-res photos of my board if that would help.

Thank you, Rodeodave, for your suggestion regarding square waves. It does look as if my waveform is close to the one that shows high-freq problems. It is not the scope probe calibration causing my strange waveform. I was sure to check probe calibration before I shot the photos. I'll see if I can find any of the references the author provides.
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Old 6th July 2012, 09:38 AM   #40
alkasar is offline alkasar  France
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I bought a finished board from good.feedback about a year ago. It was a good experience. At the time, he disappeared a few days, as his wife got a baby the day I placed my order. Maybe another baby coming


I finally bought DAC6, the USB input only version with TE7022 + WM8741, on ebay from minishow0328. It's a finished board, not available as a kit.
He is not the cheapest vendor, but english communication was excellent with Yao. Shipment with tracking number.
It arrived today. Excellent packing, very safe, and only 12 days to from Singapore to France, delivery against signature

He does not have the DAC6 v1.0 schematic and said Weiliang does not want to share it I'll have to reverse engineer the schematic from board.

This board has only one dual opamp at the output, OPA2134 despite ebay description says AD827, probably for unbalancing.

A first glance at the boad shows excellent built quality. The board is yellow now. Caps are Elna Silmic, smaller ones are Elna SilmicII. Sanyo Oscon, Wima mks and MKP in the output area.

Main filtering caps are Samwha 4700uF/35V . Never heard before about these caps. I had terrible experience with some chinese caps. These are Korean. Anyone knows how good they are ?

BTW, for those interested in USB, it seems the default windows driver has some issues with TE7022.
The latest version of driver can be downloaded from this link
少帅音响-下载中心-TeraLink-X2 USB Audio 支持WIN7-64位系统
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