[LAU] can't hear the LFE channel

Florin Andrei florin at andrei.myip.org
Fri Feb 22 03:00:35 EST 2008

Ubuntu 7.04
sound card Delta 1010
The speakers are connected to outputs #1 and 2 on the card.
This works very well for stereo stuff.

Today I put the Avia II DVD in the system and played the audio tests
using Xine as a software DVD player. Xine uses ALSA for output.
The Dolby 5.1 test for identifying the speakers was fine for the most part:
- I could hear the front left and the surround left channel in the left
- the front right and surround right channels in the right speaker
- the front center channel in both speakers

However, I hear nothing during the LFE (subwoofer) channel test. Yes, my
audio chain should be able to reproduce that frequency, it's a pair of
fairly good studio monitors connected through a Mackie box to the 1010.

I tried to reconfigure Xine, changed a few things in the Audio section,
but still nothing.

There are some other tests for the speakers, containing low frequency 
signal, and those played just fine. It looks like if there's signal only 
in the LFE channel, while the other channels are silent, then no sound 
is reproduced.

I could only test with Xine, other players either crash or don't work 
very well on this machine.

Same test failed on the laptop:
ThinkPad T60
sound card Intel 82801G
Ubuntu 7.10

It also failed on another laptop running Vista, tested with several 
players - Windows Media Player, VLC, some Dell media player. Same deal: 
if there's signal only in the LFE channel, then no signal is reproduced.

The DVD is fine, I put it in my hardware DVD player and the LFE channel 
test played just fine.

Florin Andrei


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