Subject: [linux-audio-user] Weird noise on 1010LT inputs; low level on PCM output
From: e. j. branagan - the MUSE (laug_AT_themusenashville.com)
Date: Tue Oct 12 2004 - 04:02:51 EEST
I'm running FC1/Planet CCRMA and Mandrake 9.2 (dual boot).
It took me a long time to get the 1010LT to pass sound from a pair of inputs to a pair of outputs under Mandrake 9.2; I'm not sure what I changed to make it work, but now under both operating systems, I no longer get signal through the card. IPGA, HW and ADC levels are turned up, and channels are all unmuted, etc.
However, I am now getting a weird, low volume, almost periodic noise on all 8 analog inputs. It typically repeats with a cycle of 1 sec., and sounds like a muffled drumbeat with a short pause about once a second. The same noise is very loud on the mystery capture ports 11 and 12.
Seemingly, the only major change which correlates with the loss of signal throughput and aquisition of noise is installation of another disk drive, and creation of a FC1/Planet system on that drive - but I lost signal on the unaltered MDK9.2 system as well. Removing the new drive and booting MDK9.2 doesn't help.
Then I noticed that the pause correlated with qjackctl writing a line to the Messages panel. Then I found out that running 'while true; do cat big-text-file; done' in a terminal window almost completely eliminates this sound. Running a compile results in silence for the duration of the compile.
So it seems to be related to my CPU going into some sort of idle state; as long as I keep it busy, the noise is surpressed.
Anyone experience anything like this? I'm at a loss to figure out if this is a setup/config issue, a motherboard/processor problem (its an old PIII/500Mhz), or a hardware problem with the 1010LT. Since I lost the ability to pass signal, I'm worried that the card might have died. Since I have the same symptoms on two different OS distributions, with different versions of just about everything, I don't think its a software problem.
I did finally get it to produce sound via libjack and the PCM outputs last night, but I have to turn the output levels up all the way in envy24control and the volume knob on my amp all the way up to hear it; with my tuner, this volume setting would produce massive loud distortion and result in a visit from the police about a noise complaint. If I set the patchbay to send 'digital mix' to HW out 1/2 and turn up PCM 1/2 in the monitor mixer, I see very high levels in the monitor mix meters, dispite very low output signal. DAC 1/2 levels are turned up all the way (Actually I resorted to turning EVERYTHING up all the way). I can't believe the output signal level is actually supposed to be so low. Is my 1010LT sick or dead?
-- e. j. branagan the MUSE § Nashville, TN
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