> > > Damien Brossard 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 >> > > Hi, > > I tried the "model" solution, but it did not solve the problem for me. > > Playing a bit with "PCM Volume" in alsamixer allows me to give a better > description of what can be heared (very clear when you use "-t sine" option > with speaker-test) : > * the distortion played on center channel looks like the same tone but in > higher octave (that's remind me of harmonics - if the term have any sense in > english), I don't know how to clearly explain the phenomenon, but the center > channel plays a higher frequency than the one played on left channels (front > or rear), few octaves higher (original frequency multiplied by an unknown > factor) > > Damien. > Hi. Sorry for bringing back my problem. I was finally able to test my board under Vista with Realtek drivers. The sound produced is nice and much more loud than with alsa 1.0.20. I can hear no distortion as well. So my conclusion is : software issue. Perhaps an interesting thing to notice is that with Vista, i must plug my rear speakers on the side slot, while with alsa i use the rear slot. Is there a way to dump the codec configuration (as with /proc/asound/card0/codec#0) in Windows so as to be able to compare it with the one obtained in Linux ? Thanks Damien. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
