CM6631 usb audio interface .... any good ?

[luxury54]

it seems like you already have the OEM firmware + driver if you have I2S output but you don't have the SPDIF output;
so if you want SPDIF out you must flash the firmware + driver supplied for Asus Essence One (that includes this CM6631 chipset)

the link is here and you must select your OS (operating system) before

SUPPORT

in firmware section the first one is the firmware update tool and there you have also the newest firmware

you'll need to install the new firmware and also the new asus driver to support SPDIF; anytime you want to convert back to OEM version (I2S but without SPDIF) then you must flash the OEM firmware + OEM driver from that link I provided earlier (nutsaudio)

[tdtsai]

Hi wklie:
You can't use the version of firmware. The firmware is for CM6631 chip not for CM6631A chip. If you update this firmware to your device, you device will not function any more. You should find the firmware for USB-to-SPDIF. The VID/PID should be 0x0D8C/0x0319.

Originally Posted by wklie

Hi luxury54, I did try the linked driver before. I think that driver is the April 2012 version, which refuses to install on my setup (cannot detect the CMedia USB) - perhaps because it's expecting CM6631 instead of CM6631A.

I also looked at the firmware zip and the pdf inside. This firmware is the 2203 version. I do not dare to try this out because (1) I cannot restore to my current firmware if it goes wrong; and (2) I'm afraid it might not support CM6631A.

If I were to go through a firmware reflash, it's not clear to me how to choose SPDIF or I2S (different PID?) - could you explain that? Thanks.

[KlipschKid]

Tsai - I just want to say thanks for contributing to this thread. Do you mind me asking how you know the full range of product ids etc ? C-Media don't seem to like to give out much info, and I'd really like to know more about the differences between the 31 and 31A.

For example, the 31A seems to need a USB ground connection at start up but after that the ground can be disconnected and it can have fully independent power. But the 31 doesn't seem to need this. I wonder why....

thanks

[tdtsai]

Hi KlipschKid:
The major different of CM6631A and CM6631 is sample rate support. CM6631A support 176.4K sample rate in IIS mode but CM6631 do not support it. Other feature is the same.

Originally Posted by KlipschKid

Tsai - I just want to say thanks for contributing to this thread. Do you mind me asking how you know the full range of product ids etc ? C-Media don't seem to like to give out much info, and I'd really like to know more about the differences between the 31 and 31A.

For example, the 31A seems to need a USB ground connection at start up but after that the ground can be disconnected and it can have fully independent power. But the 31 doesn't seem to need this. I wonder why....

thanks

[KlipschKid]

If anyone has bought a cm6631a for synch with ES9018, the board has simple pin headers but regular cable degrades the signal, and there's no u.fl pad. So I have made a u.fl cable to fit. It's not that easy to do - I cut the skin off slowly with a very harp craft knife and then scraped the shield wire back to expose the core cable. Then I wrapped sole solid core copper from cat6 cable around the shield. I found it quite fiddly but it's done and works.

[cogitech]

Hello all,

I have been lurking here and really appreciate all the info so far.

I have ordered a board from China with the CM6631A on it. I assume it will have the Asus firmware on it because it is equipped with coax and optical SPDIF.

I have also ordered a DAC from China which is based on WM8740 and DIR9001. The WM8740 can do 192/24, but the DIR9001 is limited to 96/24, so I do not necessarily want to use the SPDIF between the two boards.

My question: Could I bypass the DIR9001 by simply flashing my CM6631A to the OEM (I2S) firmware and then use fine wires to connect the 4 I2S (out) pins on the CM6631 to the 4 I2S (in) pins of the WM8740 chip on the DAC board?

Has anyone ever "daisy-chained" between boards like this to bypass DIR9001 and/or SPDIF?

[cogitech]

Oh, by the way, to the Linux users out there; I have read that upgrading to kernel 3.7 will solve some CM6631 issues and also bring full support for USB2 audio (past 96k).

[KlipschKid]

Seems possible - people here do it all the time - diyaudio - but without seeing the boards, it's hard to say if it will be easy or better.

[cogitech]

The two boards are:

24bit /192KHz CM6631A USB to SPDIF coaxial DAC SC | eBay

coaxial DIR9001 + WM8740DAC decoders USB + coaxial G-1 | eBay

[KlipschKid]

The DAC board looks hackable - the chips seem to be soic so that's not so bad if you have experience with smt and a reasonably good iron with a fine tip. The CM board looks close to impossible. You'll need top notch skills.

This CM board has spdif and I2S :

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

I can't find any half-decent pre-built I2S-input DACs on Ebay. Do you know AMB ? AMB does the y2 dac but it also has smt chips to do. It is WM8741 and I2S input.

http://www.amb.org/audio/gamma2/

I made one with CM :

http://www.flickr.com/photos/3030350...n/photostream/

I sell it to you if want but it's worth more than the Ebay stuff I'm afraid. I have another y2 with no cm already built too. Too many DACs eh ?