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CM6631 usb audio interface .... any good?
CM6631 usb audio interface .... any good?
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Old 27th December 2018, 05:17 PM   #761
AndersHa is offline AndersHa  Sweden
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Quote:
Originally Posted by Kuba_eM View Post
With the help of the firmware you can choose the availability of i/o's (playback and records), using the mixer you can choose which of the available i/o's are active at the given moment.
Thanks, I think I've got enough confidence to continue with the schematics. This is a rather slow progress project, but I will report progress here.
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Old 10th January 2019, 11:05 AM   #762
spirakos is offline spirakos  Greece
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Hello,

I have recently made a try to replace CM6631A with CM6632A as i found them to have the same pinout
Once i replaced it i got a message of uknown audio device so i put back the CM6631A

Has anyone tried the same before? Was the chip defective or it is just not compatible?
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Old 10th January 2019, 02:21 PM   #763
shanghai2004 is offline shanghai2004  Taiwan
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CM6631 usb audio interface .... any good?
Quote:
Originally Posted by spirakos View Post
Hello,

I have recently made a try to replace CM6631A with CM6632A as i found them to have the same pinout
Once i replaced it i got a message of uknown audio device so i put back the CM6631A

Has anyone tried the same before? Was the chip defective or it is just not compatible?
They are compatible for pin-out but the software is different.

Before you remove the old chip, erase the f/w. Then flash new f/w for the CM6632A after you put it in. The f/w for the 6631A and 6632A are not compatible. You need 6632A f/w for the 6632A, putting 6631A f/w into a board with 6632A makes it hang during startup.
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Old 11th January 2019, 01:19 PM   #764
spirakos is offline spirakos  Greece
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This is the original board with the 6631A
Click the image to open in full size.

The 6631A is the one i want to replace with the 6632A so i can have DSD support

I have downloaded all tdtsai's documentation
What i want is only one I2S master output to connect the es9018k2m dac for stereo

I'll firstly read the ducuments and after that i'll return with more questions

Thanks
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Old 12th January 2019, 04:31 AM   #765
shanghai2004 is offline shanghai2004  Taiwan
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CM6631 usb audio interface .... any good?
Default More pins needed

Hi,

For DSD with ESS, you need 2 additional pins (data-1 and GPIO10) from the CM chip compared to PCM. Not sure if the board you're trying to use exposes these pins in an easy to connect way.

Schematic attached,

I have some (empty) 4 layer PCB's with the correct pin-out. PM me if you're interested.
Attached Images
File Type: png CM6632A-switch.PNG (16.7 KB, 109 views)
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Old 19th January 2019, 10:44 AM   #766
AndersHa is offline AndersHa  Sweden
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Join Date: Feb 2013
Default CM6631A schematics using S/PDIF input

Hi,

Now a first draft version of schematics around the CM6631A device using optical S/PDIF input, USB audio interface and I2S digital audio output to sample rate converter. Any comments are wellcome!

Amp1v1.jpg

Last edited by AndersHa; 19th January 2019 at 10:46 AM.
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Old 19th January 2019, 05:26 PM   #767
Markw4 is offline Markw4  United States
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The device can only accept SPDIF input up to 96kHz, it won't go up to 192kHz?
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Old 19th January 2019, 07:03 PM   #768
AndersHa is offline AndersHa  Sweden
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Thanks for the comment!

As read from the CM6631A datasheet "RDMA#C supports S/PDIF input (192KHz is supported only with Crystal and PLL clock source)" My guess is that the firmware created by the Firmware Configuration Tool does not support this clock mode? Or is it an undocumented feature?
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Old 19th January 2019, 07:23 PM   #769
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by AndersHa View Post
My guess is that the firmware created by the Firmware Configuration Tool does not support this clock mode? Or is it an undocumented feature?
Don't know the answer myself. Maybe someone can chime in if they do. I was only commenting on the TOSLINK input but no SPDIF (coaxial), since TOSLINK is limited to 96kHz maximum sample rate with many devices due to problems with excessive jitter above that sample rate.
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Old 19th January 2019, 08:08 PM   #770
AndersHa is offline AndersHa  Sweden
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Quote:
Originally Posted by Markw4 View Post
problems with excessive jitter above that sample rate.
Yes, jitter may be an issue at 192kHz. My "cure" to this is that I have a sample rate converter between the CM6631A and the DAC. Anyway, it seems like 192kHz might be hard to support from the S/PDIF input due to limitations in firmware.
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