Inside the SYBA SD-CM-UAUD USB Stereo Audio Adapter

SYBA SD-CM-UAUD USB Stereo Audio Adapter

I am using this tiny USB-audio adapter as part of my Wifi Radio project.  It’s a ridiculously cheap $8 at and contains a C-Media CM119 chip targeted at VoIP applications.  I have no idea why they chose to use a VoIP chip for this application because it contains a lot of bells and whistles that are not being used in this device, such as support for a matrix keypad!

SYBA SD-CM-UAUD USB Stereo Audio Adapter

Unfortunately, I have not been able to locate a datasheet for the CM119 so for now I will be using it only for it’s intended application – adding an audio output to a wireless router with USB.  Come to think of it, that is probably not it’s intended application, but it’s close enough.  Hooray for embedded Linux!

SYBA SD-CM-UAUD USB Stereo Audio Adapter

15 thoughts on “Inside the SYBA SD-CM-UAUD USB Stereo Audio Adapter”

  1. Just a note for supported hardware, I was able to get the USB SIIG Soundwave 7.1 card to work just fine. It cost me a whole $4 and has a built in preamp.

  2. Has anyone tried using the adapter included with the Samsung – Pleomax Crystal 2.0 USB Speaker, PSP-7000W speakers found at walmart, amazon, etc? I’m curious if it would require a different driver or if the kmod-usb-core and kmod-sound-core would cover it. I’m also curious about how loud they might be…anyone know?

  3. It (the wifi radio) also works with an USB sound card
    based on chips from Texas Instruments.
    You can find an overview here:
    These chips are often used for somewhat better sound adaptors
    with S/PDIF. And they are easier to get than the C-Media chips.
    I’ve tested it with OpenWRT 8.09 on a NSLU2. Should also
    work on an ASUS router.

    1. Cool, that’s great to know. I think there’s a good chance that those chips will work in 7.09 (what I am running on the Wifi Radio) as well. Thanks!

  4. Hello mightyOhm,
    I found a datasheet from 2006 at “”. It’s quite a nice gadget.

  5. I also bought one from deal extreme, but mine was blue. If it is the same thing, it only supports 48000 bitrate audio, not the 44100 bps stream that Jeff sets up in part 5.

    in /etc/mpd.conf simply change
    format “44100:16:2”
    format “48000:16:2”

    If this doesn’t work, try looking for supported audio modes in the boot sequence.

  6. Your adapter is similar but not identical. I had no issues getting stereo output on the SYBA adapter on any of the three machines I tested it on. My guess is your problem lies with your adapter, your audio drivers, or your audio cable. Good luck!

  7. CN – You’re right, these are very useful. I’m thinking about getting another one to add a cheap headset to my desktop computer for Skype. The best part is, the CM119 is supported by Windows XP, OS X, and Linux, so pretty much any computer will work with these. I don’t even think you need to load a driver.

    I’m glad you are enjoying reading about the the Wifi Radio project. It has been a lot of fun to create.

    Thanks for stopping by!

  8. Thank you for bringing this delightful little gadget into the spotlight!

    This is the perfect little doodad for fixing audio on laptops and little slimline PCs with busted audio. I do feel a little ashamed that I’m only thinking about the uses it’s being marketed for…

    Good luck on your radio quest, and thank you for the tutorial. Beginners like me find it nice to see little “tricks” like your method for changing the serial pinout on the router.

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