Introduction

C-Media is a Taiwanese company who have designed a number of sound-chips. They generally do not manufacture sound cards, rather they design the core chips used on sound-cards by other brands. However, the end design of these cards is so similar that the drivers for one brand can be used with a card of a different brand.

C-Media based cards are interesting as they provide an inexpensive way to get bit-perfect DIO on a PC, i.e. a C-Media (aka CMI) based card capable of perfect DIO can be had for as little as 20GBP (~30USD) whilst the next cheapest option would certainly be over 100GBP.

Sometimes Asked Questions

The following questions were asked and answered on the CMI mailing list.

1. Meta

1.1. Why isn't this a FAQ?
Firstly because the questions aren't asked often enough. Also a lot of the answers here aren't supposed to be definitive, rather they form a collection of opinions and hints - please treat them as such.
1.2. How can I get information added/changed?
Contact the maintainer.
1.3. Were all these questions really asked?
No, questions like this one were made up as a way of providing information.

2. General

2.1. Where is more information available?
Try the following sites:
2.2. What cards use CMedia chips?
The following is probably an incomplete list:
  • AV510/AV511
  • Genius Soundmaker Value 5.1
  • Hercules Gamesurround Muse 5.1 DVD
  • M-Audio (Midiman) DiO 2448
  • Terratec Aureon Fun
  • Trust SoundExpert
  • Zoltrix Nightingale
2.3. Where can I buy a CMedia based card?
The Zoltrix Nightingale is available at the Clas Ohlson stores (http://www.clasohlson.se/) in Sweden. (Anders Ejdeling)
Nightingale spotted at a London Computer Fair, the one that used to be on Tottenham Court Road. (Duncan)
Trust Sound Expert from http://www.source.uk.com. (Rich Hanson)
The Terratec Aureon Fun is pretty easy to find mail order. (Duncan)
2.4. CMedia or Soundblaster Live?
Do you need a superb midi card with loadable soundfonts? Live!
Do You need a card able to record from digital sources with 1-to-1 perfect quality? CMedia
Do You need a card able to play up to 15 digital streams with different sample-rate/bit at the same time? Live!
Do You need a card just to listen to system sounds and mp3 with average analogue quality and 1-to-1 perfect digital-out quality? CMedia (Blueraf)
In my own experience, the 8738 has a D/A and opamp stage comparable to most AC97 solutions on the likes of the SBLive.
I never thought my SBLive Value sounded particularly good (my reference Vortex 2 was significantly better), and a recent experience with the 8738 driving Sennheiser HD600s directly confirmed that this card really is quite competent, to the extent where I'd pick it over an SBLive for output quality, regardless of whether comparing the onboard D/A or the digital output (where the 8738 is streets ahead due to its lack of resampling). (Tom Browne)

3. Drivers

3.1. Where can I get drivers?
The manufacturer of your card/motherboard should have them available for download. Failing that, try C-Media themselves.
3.2. How do I get 4-speaker support with Windows XP?
You have to enable the virtual 5.1 sound in the Mixer.exe program with the WDM drivers. (Xenomorph)
3.3. How do I get sound working for DOS games in Windows 2000/XP?
DOS games aren't going to work too well in Win2k/XP.
For best DOS results, use Windows 98, and the VXD drivers for the CMedia card.
With the VXD drivers in Win9x, they better support old Legacy programs and settings. (such as setting the IRQ, DMA, I/O Port, etc) (Xenomorph)
3.4. My main volume slider and mute is disabled.
S/PDIF streams usually won't respond to volume control. Only the analogue outs do. (Steve Corey)
3.5. Why do I get no output with clips recorded at 48KHz
Check that the loop-back feature isn't turned on. The option can be found in the Audio Rack software. (Ryan Kd)
3.6. Do the drivers support having more than one CMedia card in a machine at once? I'd like to use multiple cards for multi-tracking.
I have an Iwill KK266 mobo with onboard 8738, and also an M-Audio DiO 2448 with an 8738. They co-exist happily under Win2000, and I tried them using the same drivers, as well as the different drivers from their respective websites. (Steve Corey)
One problem with that idea is that the cards would all be running on a separate clock (crystal). I have also tried the idea under win98 with no success, I should try the new drivers. It would probably be possible to run the clock signals from just one card. ie disconnect the crystal from the other cards. (Greg Macmillan)
3.7. What about support for non-Windows operating systems?
For Linux users, ALSA supports CMedia cards. Current versions of NetBSD and OpenBSD have built in support. Last time I checked the NetBSD driver supported S/PDIF whilst the OpenBSD driver didn't. (Duncan)

4. Hardware

4.1. Do I need to connect the wires (analogue and digital) from my CD-ROM to my sound card?
If you have been playing CDs successfully without any of these wires, then you don't need them - Windows 98SE and later can play CDs from your CD-ROM by ripping the audio data and playing it digitally through the sound card in the same way as it would a WAV or MP3 etc. (Rich Hanson/Xenomorph)
4.2. Is there a device which converts from mic-in or line-in into S/PDIF out with low latency?
Any MD deck which can be put into monitoring mode (and has the necessary I/O, of course) will do this - latency will be very low (around 3-5ms at most, I reckon). It'd be a whole lot easier just to run Audio Repeater on an 833x, though... comes as part of the Virtual Audio Cable program... (Tom Browne)
4.3. Which of the 8738 based boards has the best analogue output quality?
Since the output stage is mostly built into the chip (and most of the boards are built from the C-Media reference design), they all pretty much sound the same, AFAIK...
I've had a few makes (Artis, Mentor, Audio Excel) and never noticed any sonic differences, though I can't say I was critically listening. (Tom Browne)

5. Applications

5.1. Do CMedia cards work with PowerDVD?
I'm not sure if PowerDVD officially supports Dolby Digital output with sound cards other than Sound Blaster Live under Windows 2000. But I've seen reports of PowerDVD 2.55 working while 3.0 not working. However, several people at http://www.avsforum.com have claimed to have PowerDVD3-Win2k-CMI8738 working (I haven't).
Anyway, Dolby Digital is not supported by Windows 2000 prior to Service Pack 2 so make sure it has been installed! (Hankarhu)