Jaunty 9.04, jackd and two Gina 24 soundcards

Luke Yelavich themuso at ubuntu.com
Sun Aug 16 23:51:38 BST 2009

On Mon, Aug 17, 2009 at 07:14:13AM EST, Richard Lamont wrote:
> After much googling several people say that the only way to get two
> cards to work with jackd is to do the alsa pcm_multi thing. Is this
> still the case or is it out of date? I suspect the latter, because
> hw:0,1 appears as an option in qjackctl's setup screen.

The first thing you need to do, is make one card the clock master, and slave the other card to it. When you set up multiple cards tied together with jack, you MUST make sure they both have the same clock so they don't drift appart. This is usually possible either via wordclock or S/PDIF.

The next thing you need is some code in a .asoundrc file that you can tell jack to use, so you can use more than one sound card simultaneously. I know of a page that talks about this. It uses envy24 based cards, but its no different, you will just have to adapt the asoundrc code to suit your hardware. http://www.sound-man.co.uk/linuxaudio/ice1712multi.html

I have successfully done this with 3 envy24 based cards, and it has worked perfectly, once I slaved them to each other to have the same clock.

I have actually been thinking as to whether it would be possible to write a tool that helps users set this up more easily, in terms of writing the asoundrc code needed to make this work.

If you have any questions, feel free to reply and ask.


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