CM6631 usb audio interface .... any good?

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W

wklie

Member
Joined 2013
ttan98 said:
Hi Fellows,
If someone can recommend me a model to buy at Ebay I would appreciate it. I have my eye on this model:
eBay Australia: Buy new & used fashion, electronics & home d?r

what do you think?
Click to expand...

I think this is one of Weiliang's design. You need to confirm with the seller about two things:
1. It is using PCB revision 1.4 instead of older (e.g. 1.3)
2. If you care about 176.4kHz (and 88.2kHz), you need to make sure it comes with CM6631A instead of CM6631. Assuming the item description is up-to-date, it does not sound like it is using CM6631A.
 
T

ttan98

Member
Joined 2006
wklie said:
I think this is one of Weiliang's design. You need to confirm with the seller about two things:
1. It is using PCB revision 1.4 instead of older (e.g. 1.3)
2. If you care about 176.4kHz (and 88.2kHz), you need to make sure it comes with CM6631A instead of CM6631. Assuming the item description is up-to-date, it does not sound like it is using CM6631A.
Click to expand...

Thanks for your input, technically when do you use 176.4khz, when you need to over sample 44.1khz audio stream coming from CDs? If this is not the case when do you use it? If this is the case why do you have to over sample it, better audio?
 
T

ttan98

Member
Joined 2006
W

wklie

Member
Joined 2013
ttan98 said:
Thanks for your input, technically when do you use 176.4khz, when you need to over sample 44.1khz audio stream coming from CDs? If this is not the case when do you use it? If this is the case why do you have to over sample it, better audio?
Click to expand...

I don't actually do these (my 10-year old AV receiver maxes out at 96kHz), but my understanding of the benefits of 176.4kHz is:
1. DSD to PCM conversion, if you purchase DSD files or rip from SACD using a hacked PS3
2. Some people prefer integer multiple of upsampling, i.e. 44.1kHz -> 176.4kHz instead of 44.1kHz -> 192kHz.
 
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terranigma

terranigma

Member
Joined 2007
Is there anyone who familiar with these boars?

taobao agent CM6631 an absolute fever b USB turn coaxial finished Board - TMALL outlet,TMALL english,TaoBao Agent, English Taobao, Taobao Outlet - Products Online from China TMALL at 12got.com
China Wholesale - The CM6631 absolute fever version USB to coaxial finished board - 31.22 - China service

This one has 26C32 buffer and RJ45 socket for i2s. The buffer used for i2s or Spdif (or both?) is not clear for me.

China Wholesale - A CM6631 fever version - 40.98 - China service
 
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N

Navyblue

Member
Joined 2012
I am interested in getting one of these. I need:

- Mac full compatibility
- SPDIF output (if I can easily add SPDIF with the I2S board I am all ears)
- 88.2k compatibility is preferred, but if it save me enough money I am willing to let this go

This seems to fit the bill, but uncased and no option for external power supply.

24bit 192kHz CM6631A USB to SPDIF Coaxial DAC USB Power SC | eBay

This one is almost perfect but doesn't do 88.2k.

New Hi Fi CM6631 USB to Coaxial Optical SPDIF Convertor for DAC 192kHz 24bit | eBay

Are the ones from diyinhk better? But it is uncased and has no SPDIF.

24bit 192kHz USB to I2S SPDIF PCB CM6631 with Ultralow Noise 6 5UV Regulator | eBay

My question is, are they made equal (or almost)? Which ones should I be looking at?
 
W

wklie

Member
Joined 2013
I can't find boards equivalent to terranigma's links from taobao (so cannot find any comments.)

As for Navyblue's 1st link, I can find it from taobao but there are almost no useful comments. Due to post #228, I'd recommend having the option of external power.

2nd link: my comments in post #261 are applicable.

I don't believe they are made equal due to different designs and components, and quality of soldering as many of them are hand made. I use the one in post #34 (with optional TCXO upgrade.)
 
W

wklie

Member
Joined 2013
terranigma said:
Taobao links:
The narrower boards same but different revisions.
Click to expand...

The seller got excellent ratings. I read all the comments - there are no negative comments (taobao usually has very few negative comments, but having absolutely none is most certainly good.). All comments about the build quality are good. Most reported improved audio quality but two said it (the narrow blue version) still cannot compare with CD players.

I think, but am not 100% sure, the differences among the three are:
- The narrow green version is the oldest
- The narrow blue version is newer and has coaxial output
- The more expensive wide blue version has coaxial, optical (but the photo does not show the connector?!), I2S output and may have better components.

0.1ppm TCXO upgrade costs RMB140 extra.
 
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N

Navyblue

Member
Joined 2012
wklie said:
As for Navyblue's 1st link, I can find it from taobao but there are almost no useful comments. Due to post #228, I'd recommend having the option of external power.

2nd link: my comments in post #261 are applicable.

I don't believe they are made equal due to different designs and components, and quality of soldering as many of them are hand made. I use the one in post #34 (with optional TCXO upgrade.)
Click to expand...

Thanks. :)

As of now, I think the path of least resistance is the second link.

Is there a particular seller that has best/good reputation?

I don't rule out Taobao either, just haven't figure out how to make a purchase there.
 
terranigma

terranigma

Member
Joined 2007
wklie said:
The seller got excellent ratings. I read all the comments - there are no negative comments (taobao usually has very few negative comments, but having absolutely none is most certainly good.). All comments about the build quality are good. Most reported improved audio quality but two said it (the narrow blue version) still cannot compare with CD players.

I think, but am not 100% sure, the differences among the three are:
- The narrow green version is the oldest
- The narrow blue version is newer and has coaxial output
- The more expensive wide blue version has coaxial, optical (but the photo does not show the connector?!), I2S output and may have better components.

0.1ppm TCXO upgrade costs RMB140 extra.
Click to expand...

Thank you for good brief. I'm actually looking for a easy customizable (reg+oscillator modifications) layout and close-to-chip I2S tapping headers. Narrow blue version seems fit for me in this perspective.

For TCXO, should I prefer replace 12Mhz one first?
 
N

Navyblue

Member
Joined 2012
For this one here, I just noticed that there is no capacitor on it, but quite a few inductor.

Hi Fi CM6631A 192kHz 24bit USB 2 0 to Coaxial Optical SPDIF Convertor DAC Board | eBay

For this one, there is neither capacitor nor inductor.

24bit 192kHz USB to I2S SPDIF PCB CM6631 with Ultralow Noise 6 5UV Regulator | eBay

Can any of you more informed folks infer anything from it? Is it a good thing to be able to do without capacitor in this kind of circuit? Or is this some kind of cost cutting measure?
 
R

rade95

Member
Joined 2010
Hi KlipschKid, I am trying to puzzle together your posts about diyinhk USB 192K CS6631A board and I am not sure why all your pictures have disappeared hindering this whole thread. I am trying to figure out how to make use of SPDIF out on that board because the pads are not solderable. The circuit should be there though, I think...Can somebody shed some light on this please. thanks
 
N

Navyblue

Member
Joined 2012
rade95 said:
Hi KlipschKid, I am trying to puzzle together your posts about diyinhk USB 192K CS6631A board and I am not sure why all your pictures have disappeared hindering this whole thread. I am trying to figure out how to make use of SPDIF out on that board because the pads are not solderable. The circuit should be there though, I think...Can somebody shed some light on this please. thanks
Click to expand...

I messaged the ebay seller recently. According to him/her, the output is only a few mA, and is good for a Toslink module. But for a coax output extra circuitry is needed.

As for KlipschKid, I wonder if you are taxing the SPDIF output? May be something like a 6:1 transformer to step down the V and beef up the I is more appropriate here? (assuming that such suitable parts exist)
 
R

rade95

Member
Joined 2010
Navyblue said:
I messaged the ebay seller recently. According to him/her, the output is only a few mA, and is good for a Toslink module. But for a coax output extra circuitry is needed.

As for KlipschKid, I wonder if you are taxing the SPDIF output? May be something like a 6:1 transformer to step down the V and beef up the I is more appropriate here? (assuming that such suitable parts exist)
Click to expand...

Yep, I got the same reply from diyinhk, so I am no longer interested in trying SPDIF outputs on the board. Its not really intended to be used. Instead I will use the board for its real intended purpose: as a USB in, I2S out board @ 192KHz and as a MCLK source for the ES9018 board.
 
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