record level sensitivity on SiS (intel8x0) audio device
 

Using Fedora core 3 on a Gigabyte 8S648-RZ motherboard with SiS onboard audio device, I find that trying to record on the line in from the tape output of an old Marantz stereo amp, the Capture slider on the ALSA volume control is far too sensitive. On the very lowest non-zero setting I get clipping and distortion on the input, increasing beyond the lowest setting causes complete saturation of the input. I believe the output levels from the amp are not excessive as I have used the same setup with different PCs in the past.

lspci output is:

00:00.0 Host bridge: Silicon Integrated Systems [SiS] SiS 645xx (rev 71)
00:01.0 PCI bridge: Silicon Integrated Systems [SiS]: Unknown device 0003
00:02.0 ISA bridge: Silicon Integrated Systems [SiS] SiS963 [MuTIOL Media IO] (rev 25)
00:02.1 SMBus: Silicon Integrated Systems [SiS] SiS961/2 SMBus Controller
00:02.5 IDE interface: Silicon Integrated Systems [SiS] 5513 [IDE]
00:02.7 Multimedia audio controller: Silicon Integrated Systems [SiS] Sound Controller (rev a0)
00:09.0 Ethernet controller: VIA Technologies, Inc. VT6102 [Rhine-II] (rev 43)
00:0b.0 SCSI storage controller: Adaptec AIC-7892A U160/m (rev 02)
00:0d.0 Ethernet controller: VIA Technologies, Inc. VT6102 [Rhine-II] (rev 43)
01:00.0 VGA compatible controller: ATI Technologies Inc Rage 128 Pro Ultra TF


The same thing happens whichever volume control software I use, including the OSS compatibilty stuff (loaded by default in FC3). Sound modules loaded are:

snd_intel8x0 34177 2
snd_ac97_codec 74937 1 snd_intel8x0
snd_pcm_oss 50673 0
snd_mixer_oss 17729 1 snd_pcm_oss
snd_pcm 98889 4 snd_intel8x0,snd_ac97_codec,snd_pcm_oss
snd_timer 32837 1 snd_pcm
snd 57285 13 snd_intel8x0,snd_ac97_codec,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_timer
soundcore 10785 1 snd
snd_page_alloc 9669 2 snd_intel8x0,snd_pcm


Any ideas what might be causing this, or any work around, other than trying to wire someting to attenuate the incoming signal?


Thanks,

David

Using alsamixer, what's the "Capture" setting on the Capture view (F4)? If it's anything above 0 try lowering it.

Using amixer shows an allowed range of 0-15. 1 is 7%, which shows the clipping I dexcribed, 0 shuts it off completely.

Line is at 0 and muted? (sorry about asking about Capture which was in your original post - I was tired)

Not muted

I noticed today that with my onboard audio (also AC97) output is fed back in on line input for some reason. That is, with no signal coming in on line it's recording whatever is currently playing. I don't have the same problem with a SB Live card that's also installed. Try muting everything and test the line input levels - if it's ok, then you have some internal feedback.

No, that's not it. I was testing with everything muted other than the line in and capture. I'm just about to try attenuating the output from the amplifier. I've found you can buy attenuators for this kind of purpose for £30 a pair so I've bought some resistors and phono plugs for about a quid to make up my own.

I've put my attenuator together and it solves the problem