Two soundcards or one?

I got my Scarlett 18i20 working on Linux. I get all system sounds as well as jack connection. All works fine. I can see the latency in the Jack configuration which is 2ms. I think that is too optimistic but I am not too concerned about latency at the moment.
I have a question: I am running Pulse server for all the regular (system, multimedia, video) sounds. I could use the pulseaudio-module-jack to run everything through Scarlett. I am wandering though. What would be the best configuration? Should I enable the on board sound-card (disabled at the moment) and dedicate that to system sounds and have Scarlett serve only Ardour through Jack? Or is it better to use Scarlett for everything?
With my rough knowledge of how system works I would say it would be better not to push any more through USB than necessary.
What would give me the best performance in Ardour?

From my experience it’s best to disable pulse completely while you use jack. A convenient way to to that is by invoking jackd (typically through qjackctl) with a command like pasuspender qjackctl &. That way you won’t hear any system sounds and can’t distract yourself through youtube, but these conveniences are back once you quit jackd.
I do use the on-board sound chip for the mundane stuff and the multi-channel card for recording music, but it doesn’t really matter because “system sound” and “jack” are mutually exclusive in the above scenario, and that’s a good thing.

Thanks Seb. I’ll try that.

Hi Seb,

Can you put pasuspender parameter somewhere in qjackctl setup interface or do you start qjackctl with the parameter already in place?

I don’t use pulse at all, and have jackd running all the time on my recording pc.

There http://jackaudio.org/faq are some tips for (see How can I play audio from … via JACK? section)

That’s what I had Lazyklimm but I do not have a dedicated recoding PC at the Moment. I would like to run pulse for system, Youtube and stuff like that and use USB driver via Jack for recording only.

Hi,

There is another way, both AV Linux and KXStudio use an ‘aloop-daemon’ (a script by KXStudio’s falkTX) that creates a loopback device to any ALSA applications automatically route their audio to the selected running JACK device. For example you have JACK running on your system and want to have Youtube audio from your web browser and audio from a Virtual machine in Virtualbox which both use ALSA… no problem! If you are running the aloop-daemon this is all taken care of by the aloop-daemon and PulseAudio is not even installed on the system.

This is available to all Ubuntu users through the KXStudio PPA’s in the ‘Cadence’ package and it comes as a standalone app in AV Linux.

*NOTE the aloop-daemon requires the ‘snd-aloop’ Kernel module to be loaded at boot, some distros do this by default, some don’t…

Hi,

There is another way, both AV Linux and KXStudio use an ‘aloop-daemon’ (a script by KXStudio’s falkTX) that creates a loopback device to any ALSA applications automatically route their audio to the selected running JACK device. For example you have JACK running on your system and want to have Youtube audio from your web browser and audio from a Virtual machine in Virtualbox which both use ALSA… no problem! If you are running the aloop-daemon this is all taken care of by the aloop-daemon and PulseAudio is not even installed on the system.

This is available to all Ubuntu users through the KXStudio PPA’s in the ‘Cadence’ package and it comes as a standalone app in AV Linux.

*NOTE the aloop-daemon requires the ‘snd-aloop’ Kernel module to be loaded at boot, some distros do this by default, some don’t…

This is how i have my pc running, kx studio has it all setup for you out the box so no playing around. I had ubuntu studio and spent ages trying to get the alsa-jack and jack-also working properly but it would be problematic.

it just works in kx studio, however i have problems in ardour trying o export when the also- jack bridge is running, it exports but then freezes and xruns start counting up, after that ardour will not export, i have to disable to also-jack bridge when exporting.

The alsa jack bridge can come in handy, if you want to run a non jack aware program into ardour and record it.