# Realtek ALC1200, lots of static noise when playing music

## neocui

I got the brand new ASUS GeForce 8300 motherboard last week. It has an onboard Realtek ALC1200 HDA chip. When I play music, there is a lot of static noise. It happens whether I output through analog or S/PDIF, so I know it's not interference.

I'm running vanilla 2.6.25.9 kernel. I tried the bundled ALSA-1.06-rc2, as well as alsa-drivers-1.06 from portage, as well as the realtek release of ALSA-1.06 from their website. It's the same problem, altho it appears that the problem is less severe with the realtek drivers.

Does anyone know what might be causing this? Is there a configuration parameter I missed?

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## poly_poly-man

it's too close to the rest of the system... onboard sound always has problems like this (usually static, I've seen other problems, but not often)

This is not a software problem (though some software may mask it), it's a hardware problem. Use a PCI card, or better, external.

EDIT: the reason it's on both analog and digital is the way it works - the interference comes in before it's analog,

poly-p man

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## neocui

Assuming it that's all digital, and never gets converted to analog, why would the signal be suceptible to interference?

Ok, I'm going to verify your claim by installing Vista... If vista also has these problems, then you are right.

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## neocui

Works perfectly in Vista. No noise at all. So that disproves your theory.

I'm pretty sure this is a driver issue. Realtek will probably fix it at one point...

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## CanuteTheGreat

This might be too obvious, but worth checking: see if there is a "PCM" device listed in the volume controls (i.e. alsamixer) and make sure it's not at 100%. I have a similar problem on one machine (but it's intel-hda sound, so ymmv) and decreasing the PCM volume down to around 70-75% eliminates the distortion.

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## neocui

I use spdif output, so the PCM volume control does nothing. Raw PCM gets passed through SPDIF.

I'm almost 100% sure this is a timing issue in the device driver. Because not only there is noise. It appears that the the music is playing slower, as if it's continuously pausing and resuming. Also, I can make the problem worse by cranking up the processor clock rate, using cpufreq-utils.

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## MotivatedTea

Are you using the "snd-hda-intel" module? If so, try different values for the "position_fix" module parameter. (You said you had a Realtek HDA chip, but the only "HDA" I know of is Intel's High Definition Audio? Maybe Realtek is using Intel's chips?) My laptop has an older version of an Intel HDA audio chipset, and I had to try different values before I found one that worked.

See the file "/usr/src/linux/Documentation/sound/alsa/ALSA-Configuration.txt" (assuing /usr/src/linux is a symlink to your kernel source tree) and search for "position_fix" for more information. In particular, the possible values for position_fix are:

```
 position_fix - Fix DMA pointer (0 = auto, 1 = none, 2 = POSBUF, 3 = FIFO size)

```

You may also want to try turning "enable_msi" on or off to see if it make a difference.

To test different values, either unload and re-load the modules manually with modprobe, or add a line like:

```
options snd-intel-hda position_fix=2

```

to the end of "/etc/modules.d/alsa", re-run "/sbin/update-modules", and then "/etc/init.d/alsasound restart".

HTH

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## soth

I had some pretty bad static after getting a new mobo and found this post when searching.

After reading MotivatedTea's excellent post, I discovered I hadn't rerun alsaconf. Now that I have 

```
/etc/modules.d/alsa
```

 references the right card. Perfect sound. 

Long shot, but it might help someone.   :Cool: 

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## neocui

This has been fixed in the kernel tree. The trick was to enable "snooping" whatever that means.

http://lkml.org/lkml/2008/8/4/110

This problem applies to all newer nVidia HDA chips.

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