Clear 5.1 surround!


Sound – It works but my SoundBlaster Live! refuses to be a 5.1 surround sound card only delivering 2.1 sound. I think the problem is the rubbish implementation of Pulse Audio in Ubuntu! I have a potential fix.

Having read a lot of posts about Pulse Audio and how poor it is in Ubuntu I was expecting something of a fight to get this to work!

The problem was that I was getting a loud hiss from the centre speaker and no sound from the rear, hence 2.1 sound. I checked everything was working correctly by booting the PC in Windows XP (dual boot). 5.1 surround worked fine so the hardware was all connected up correctly.

On doing a bit of research on Google I found this post http://ubuntulinuxhelp.com/enable-51-surround-sound-on-linux-ubuntu-804-hardy/ which gave me a clue to the problem. Essentially Pulse audio was configured for 2 speakers. To change the settings launch terminal and cd /etc/pulse. The etc folder is where most applications store their configuration settings and each folder is named after the application like X11, apt, pulse. My preferred text editor form the command line is nano based on the pico text editor http://en.wikipedia.org/wiki/Pico_(text_editor). Unlike Vi, http://en.wikipedia.org/wiki/Vi, it is very simple to use. Backup the file before editing by entering sudo cp daemon.conf daemon.conf.bkup and then edit the file with the command sudo nano daemon.conf.

Fine the line ;default-sample-channels = 2, uncomment and change the value to 6 so it looks like

default-sample-channels = 6

WriteOut i.e Save the file in Nano by pressing Ctrl-o and then Exit by pressing Ctrl-c.

The next things I checked was Preferences > Sound and found that my AC97 on-board sound card was still enabled in the BIOS. So I logged restarted the PC and turned this off as it could be confusing Ubuntu.

Back in Ubuntu I set all the settings in Sound Preferences to SB Live (rev.10, serial:0x80641102) Multichannel Playback (ALSA), tested all worked. Set Default Mixer tracks to SB 5.1 (Alsa mixer). Still an very annoying hiss from the centre channel and still 2.1 sound.

Opened Volume Control in the system tray and noticed that Wave Centre, Wave Surround were all at at zero, whilst Surround and Centre were maximum. Bumped them all up to max, played a 5.1 surround DVD in VLC and got 5.1 Surround but still with a hiss!

I then took a look at at the switches tab in Volume Control. The SB Live Analogue/ Digital Output Jack check box was checked. I’m not using Digital Out on my card as my Creative Labs surround sound speaker system does not provide support. The hiss stopped and clear, clean 5.1 surround came to Linux.

To summarise. My on board sound was still enabled which confused Ubuntu, this is 2 channel and might explain the Pulse Audio config file being wrong. Possibly as a result of this initial problem, the default settings for my Soundblaster Live! sound card were also wrong when Ubuntu detected the card on installation and configured the software.

Despite all the above, the one thing I do appreciate about Ubuntu is the absence of driver disks for my hardware and when something goes wrong you can drop behind the GUI interface to get to the “advanced” configuration settings which are reasonably well documented. In Windows, you have to ‘hack’ the registry.

So far all of my hardware has been fully supported ‘out of the box’. I can not say the same for Windows!

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