On Thu, Oct 29, 2009 at 2:21 PM, Damien Brossard <brossard.damien@xxxxxxxxx> wrote: > > Hi. > > I recently bought a Gigabyte GA-MA78GM-S2H motherboard. This board uses the > (in)famous (from what i've read for now) alc889a chip. While playing 5.1 > content, I can hear noise or distortion coming from the center channel. I > can not test my configuration with another OS, so I can't fully dismiss a HW > problem. However, i made several tests with 5.1 and 2.0 speakers which > points me to soundcard problem. > > I've made some tests with speaker-test (speaker-test -D surround51 -c 6) : > 1) Each time a sound is played either on front left channel or rear left > channel, a noise can be heared on the center channel (and subwoofer, this is > confirmed pluging a stereo headphone on the center/lfe jack). No noise when > a sound is played on right channels (front or rear). > 2) In alsamixer, if I set the volume to 0 for the front or rear left > channels, i can hear the noise on center/lfe when a sound is "played" on > this channels > 3) In alsamixer, if I mute the front or rear left channels, i can hear no > more noise on center/lfe > > Complementary tests have been made with alsaplayer and using a simple mp3 > file. In this configuration (stereo output), center and rear channels play > the same sound as front channel. > 1) If all channels are unmuted, I hear no noise. > 2) If either the front channel or the rear channel are muted, I can hear the > noise on center channel. > > I tried this with alsa-driver 1.0.20 and 1.0.21 with the same result, I > recently went back to 1.0.20 due to kernel upgrade. > > Things that seem strange to me (maybe not so strange to alsa dev :)) : > 1) alsamixer shows volumes in percentage, however when I set a channel > volume to 50% and the master volume to 50%, I hope to find a resulting > volume of 25%, not 0. > 2) lspci reports my soundcard subsystem id as 1458:a022, but in > /proc/asound/card0/codec#0 the subsystem id is 1458:a002 > > Googling around made me find few references (in alsa-devel list) to a > similar problem : > > http://mailman.alsa-project.org/pipermail/alsa-devel/2008-July/008942.html > http://mailman.alsa-project.org/pipermail/alsa-devel/2008-August/009754.html > > The distortion / noise described here is exactly what i can hear with my > system. Apparently the user solved the issue buying another soundcard. I'd > like to be sure it is the only way to go. > > Attached is the file produced by alsa-info.sh A user had the same issue (Gigabyte P35-DS4), with alsa-info http://www.alsa-project.org/db/?f=eb49c36810be2543bcb913d80390f6cba13ec766 and he just reported back that setting the model line to options snd-hda-intel model=6stack-dig he was able to fix the problem. He tried this on Ubuntu 9.10 (Alsa 1.0.20). Assuming that it has not been fixed yet, what change would I make to the Alsa source code so that newer versions would be able to autodetect the chipset? I would appreciate such an answer, as I tend to get a few feedback reports on audio cards. Simos _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
