Hi! Benny Sjostrand wrote:
done. The DC level before the coupling capacitors at the inputs of the amps changes from 2.26V down to 0.03V when rising both PCM and master to maximum volume. The higher master and PCM level, the smaller the DC level and the more distorted the sound gets. When setting master to max and rising PCM level, in the end (at 0.03V) you don't hear any sound. The right channel reaches this state one step of the PCM mixer before the left channel. (There was some mail about slightly different levels right/left on this list, I think. Perhaps that's the reason for this slightly different behaviour of the channels?)same problem for me and my DMX XFire 1024 :-(. I think the distortion sounds like a DC offset introduced by the PCM channel. Do you also get popping noise when changing the PCM volume? It just sounds like changing the supply voltage of a running amplifier for me. Perhaps I can measure the DC level before the output capacitors or --perhaps even better-- at the input stage of the output amps? (But I don't know if the DAC used on this card can output DC voltage and if the LM386 amps are AC or DC coupled. I'll have to find a screwdriver and some time first.)
After reloading the snd-cs46xx module, the DC level of both channels stays at 2.26V regardless of the mixer settings and the sound doesn't get distorted. So, what could be the difference after reloading the module? (Did you get my /proc/asound/... dumps?)
If I could answer this question, I would be happy. Then I would have an audio component with SPDIF input :-) (Not true! I've got this XFire soundcard...)Not only the PCM sound is distorted, but everything that goes through the mixer, I think. If you lower the PCM volume and playback e.g. a CD through the CD input of the card, then the quality is OK. This seems to be a problem with the XFire only, as none of the other cs46xx users has reported this problem. Perhaps it has something to do with the audio codec (the XFire uses one codec for 4 channels, other cs46xx use two codecs for this)? Or some GPIO?Is the sound from that comes from the SPDIF interface OK ?
Before updating to Mandrake 9.0 I played around with the GPIO controls but didn't notice any change/improvement. At the moment I'm using the mdk-rpms, so I can't tests this in detail until I change back to cvs or tarball. Sorry!
Just would try to understand if the problem is digital, DSP related issue,
or something analog, CODEC related ...
Most soundcard got some kind of "amplifier", that possibly is controlled
by some GPIO, like the case of Santa Cruz, and Hercules GTXP.
If Terratec wont release and technical specifications about the card,
then you can try to play with the EPGIO hack in the cs46xx driver (compile alsa
defining the CONFIG_SND_CS46XX_DEBUG_GPIO option) and try find out
if any of the EGPIO0-7 can solve the problem.
/Benny
regards
fritz e.
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