2009/10/30 Simos Xenitellis <simos.lists@xxxxxxxxxxxxxx> > 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 > 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. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
