How to best switch between normal and lowlatency sound in Ubuntu Studio?

Support and Help
1

Ubuntu Version:

24.10

Desktop Environment (if applicable):

KDE

Problem Description:

I am using Ubuntu studio on a laptop mostly as a regular desktop system, and occasionally I used it for playing live music: Then I connect a USB audio interface (Zoom H5), connect my instrument in the input, apply some effects in Carla and output again through the interface into the external mixing board. For this I need the lowest audio latency I can get; which in my setup is a Pipewire Quantum of 64 / 48000.

I do not normally have the interface connected because this is cumbersome in day-to-day use, and I don’t need lowlatency audio when not making live music.

So when I connect the audio interface I go through a little dance:

  • Connect the audio interface
  • Configure the Audio to 64 / 48000 in Ubuntu Studio Audio Configuration
  • Reboot the computer for the configuration to take full effect
  • Start Carla and load my plugins; play

And after I am done I do the reverse:

  • Disconnect the interface
  • Reset the Quantum to the default 1024 / 48000
  • Reboot again

While this works, it is a bit cumbersome. Is there a better way to switch between General Purpose and Lowlatency Audio?

I tried skipping the reboot step, but it seems I am getting Xruns / Pipewire errors when I do not.

Would it make sense in my case to just disable Pipewire-Jack to use plain Jack? I do not need to connect to any Desktop sound sources or sinks im my setup, after all.

I would greatly appreciate any tips; and any input on whether the reboot after changing the Quantum and/or connecting the Interface is actually necessary / beneficial, or whether that is just my superstition. :smiley:

Relevant System Information:

Laptop: Thinkpad P15s
System: Ubuntu Studio 24.10 with KDE Desktop
Interface: Zoom H5 via USB

2

Have you read this: Ubuntu Studio Audio Configuration – Ubuntu Studio ? (EDIT: I see now that you do that)

You shouldn’t have to reboot, the settings take effect immediately if done through the linked tool.

Honestly, that sounds to me like a system-specific issue. Also, just because your interface is capable of 64/48000 doesn’t mean your system is. I typically run 128/48000 with my Behringer UMC404HD and rarely encounter issues, enjoying 5.3ms latency which is indistinguishable to the human ear. (FWIW, my interface is capable of 32/192000, but that is far too taxing on my processor so it does nothing but xruns).

You might also use cpupower-gui, installed by default, to increase your processor speed to maximum and have it set to the “Performance” governor. Likewise, set the Power Management settings (in the system tray, the battery icon) to “Performance.” That should help.

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3

Thank you for the quick and helpful reply!

64/48000 does actually work for me, with a pristine system. I assumed the settings only get fully applied after a reboot, but maybe it’s some leftover processes that make the difference between freshly booted and not.

I tried to squeeze the last bit of latency out because both the Zoom H5 and the main plugin I use (an octaver, inner pitch) are a bit slow and in the sum of all the latencies it eventually adds up. But you’re probably right and the little extra latency with more relaxed buffers won’t make a noticeable difference. :sweat_smile:

When I have more time I’ll go about it scientifically, see what is best for my case and write it down.

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