[alsa-devel] Sound distortions with Realtek ALC889A
Hello.
Due to a hw defect, I recently bought a Gigabyte X48-DQ6 board which utilizes a Realtek ALC889A for sound output. At first glance everything seemed fine but during day-to-day use I figured that during playback of a 5.1 file, I've to turn up the volume quite a bit to match normal 2.0 playback or the volume levels of my old board (ADI1988B). And to make matters worse, the surround channel produces (static) noise on the center channel. If I mute every channel but the surround channel, the distortions are clearly hearable. During normal 5.1 playback, they are only hearable during scenes with a lot of talk or quieter scenes which is still very annoying unfortunately. Muting the surround channel also stops the distortions on the center channel.
Also the model is not properly recognized, I've to pass model=6stack-dig to get all channels properly working with digital out.
By the way, this is with a 2.6.26-rc7 x86_64 kernel running a alsa git checkout from last monday.
I'd appreciate any help or hints I can get. Thanks in advance.
Best regards, Matthias Dahl
Hi.
Replying to my own mail with a set of new informations. Maybe those are of some help:
- no distortions under vista (doesn't help me much as I don't use it -g-)
- my revision id is different from what is expected within patch_realtek.c so I made the necessary adjustments (changed the id, and put patch_alc883 in place) and at least the volume seems to be back to normal now under 5.1 output (my revision id: 0x100101)
- those distortions worsened though: with the alc882 (6stack-dig) code, muting the surround channel during 5.1 output quit those distortions on the center channel. (not an option, but a clue) Now I have to mute front and surround channel to quieten those distortions. Things get worse also when I switch to 8 channel in alsamixer.
I have already looked around the net to find a data sheet for the ALC889A but there seems to be none available. A nice comparision chart on the Realtek site though made me believe that the chip is actually closer to the ALC885 than the ALC883.
By the way I have attached a set of data with the alc883 code in place.
Thanks for any hints or help in advance. I'll happily help where ever I can to get this fixed and working properly.
Best regards, Matthias Dahl
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Matthias Dahl