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How to get your ALC850 Sound in 5.1 Configuration.


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The same sh**t for me. With asus A8N-SLI SE mobo and ALC850. It plays just 2 speaker configuration. When setting it to 6 speaker , also plays just 2 speakers after some more configuration choosing the right speaker. Don't know how to solve this problem, read many posts, but nothing....

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I have a DFI Lanparty with ALC 850... I have the multichannel option as presented here, and each speaker has the option of 6 channels. However all 6 channels only operate 4 of the speakers! Neither the center channel nor the subwoofer will output anything (these go to other channels when selected).

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I guess ALC850 users are never going to have a fix then... the 5.1 setup method described in this thread was close, but no cigar. The speaker assignments switch randomly. Sometimes you can't even complete the configuration without it changing output channels that you've already configured and you go in a circle "chasing" the correct settings as they keep changing. Sometimes, you can get it set right for a while, then it stops whenver you start/stop iTunes or Quicktime.

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Okay, I have an Asus A8N-E with ALC850, too, and I think I know what the problem is:

The ALC850 actually has 8-channel, not just 6-channel! So every time it is accessed using 6-channel output, there's two "ignored" channels "left" and hence the output channels are rotated by 2!

Try it with some AC3 testfile in VLC. Every time you play it, it shifts 2 channels, there are 3 different layouts until it repeats. So speaker-assignment is not really random...

If you try Fraunhofer's mp3 surround player with the encoded 6channel_id.wav the layout stays the same. But it does not react in any way to what you set in the Audio/MIDI config tool... This may be due to VLC using AuHAL for an output (like it is supposed to be) while the Fraunhofer mp3 surround player probably uses the old static-windows-channelorder method VLC used before that ignores the Audio/MIDI Speaker layout (CoreAudio?)..

And if you keep in mind the 3 steps VLC cycles through and f.ex. switch LS/RS with L/R you'll notice that VLC actually reacts to the speaker layout set in Audio/MIDI config, thanks to AuHAL!

 

I also noticed that Left/Right front (aka Normal stereo) is much louder than the other channels, but I think this can be fixed using the volume sliders in Audi/MIDI config...

 

So we need to find the person that's responsible for the AC97 driver, especially the Realtek ALC850 and ask him nicely to provide 8(7.1)-channel output (which OS X can do, just check out the Pulldown in the "Assign channel" window in Audio/MIDI!). If that's too hard to do, another option would be to provide two channels of silence for the missing Left/Right side speakers..

 

A way to check that the default channel layout is correct (so that programs like the mp3 surround player that don't use AuHAL but a fixed channel order with Core Audio) still work would be to get some generic 5.1 (or 7.1 if that's even readily available!) USB-device, plug it in and check with the mp3-surround player. Don't worry, all the ones I tried worked, there's a generic USB class for such devices.. I recommend the Terratec Aureon 5.1 USB, all these 5.1-headphones make it kinda hard to tell where the sound is really coming from! ;-)

 

btw: The M-Audio Sonica Theater can do 7.1 on the Mac - but they have their own software for OS X. Still, i think they also work with Audio/MIDI if you set them to "passthrough" IIRC, but from what I remember they placed the two extra channels BEHIND the listener as some sort of "enhanced back center", not directly on the sides (like the Realtek and other PC-manufacturers aim to do)... This could be somewhat compensated for using the Speaker assignment in Audio/MIDI, just move LS/RS to L/R and the two "back centers" (can't remember what they were called) to LS/RS..

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A little update:

If you check here, you'll see that the ALC850 is the only 8-channel Codec that Realtek ever made. In other words: Users of the ALC65x Codecs won't have the problem we are experiencing, since their MoBos only offer 6 channels!

Maybe if we could edit some plist so that the 850 is recognized as an 8-channel device instead of 6-channel? That should do the job already!.. I checked the info.plist in /System/Library/Extensions/AppleAC97Audio.kext/Contents/PlugIns/AppleAC97AudioIntelICH.kext/Contents, but there's no mention of the Codec's capabilities in there... I tried changing the ICHtype of the Nvidia entry from 99 to 8 (in Intels ICH6 entry that's the only place where I can see an Integer 6!), but it didn't seem to change anything (worked just like before!)...

Anyone know any other place where we could look? IOkit.framework looks promising, lots of hits on "channel" in IOAudioDefines.h and IOAudioTypes.h...

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  • 1 month later...
Guest Snowski

Hi Kaid,

 

Thx for providing all the info lad. I'm also looking for a solution since JAS 10.4.8. The best that I can come up with is this script which resets channels to 2 (not made by me btw)

Either we get a proper kext that uses all 8 channels properly or we edit some file so that it can only use 2 channels.

 

If you're doing audio it's a blast, constantly changing from 2 to 6 channels. But then again, this card isn't made to do proper audio. Still, it's nice to do some small work in Logic using the onboard audio. Oh well, lets keep bumping this now and then until someone comes up with a cure.

 

Later amigos

FixAudioSetup.class.zip

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I don't know why but when I come to step 5, I clicked on each of the boxes to test the speakers but only two of them work (LEFT FRONT and RIGHT FRONT). The others don't have any sound!

 

Interesting. I havn't installed it yet but I am having the same problems under Windows. I was really hoping OSX wouldn't be the same. Is this soundcard native to OSX?

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I've seen a couple other people with my issue - ALC850 but no devices show in the sound control panel - but no one seems to have any solutions. Anyone? Help me make the devices show up? When the wiki says ALC850 works out of the box but on my machine it won't even show any in.out devices, it's pretty frustrating...

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I have a problem with my audio unit. the 6-channel problem after using logic 8 pro. after logic quits...the result is a switch to 6-channel mode in audio-midi-setup with the result that the sound stops immidiatelly. After that i have to select in audio-midi-setup the 2-channel output ...with the result that the sound comes back immidiatelly. did anybody helped you or do you have a solution to this complicated procedure?

 

btw. i use snow leopard 10.6.5 on my asus m2n4 sli

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