System Tweaks

There are some system tweaks that give better audio performance. As a general suggestion, it is recommended that the user install a low latency Linux kernel.

The System Tweaks tab looks like:

It has four controls:

• CPU Governor: The performance setting runs the CPU at it highest rated speed and gives the best audio performance. However, it may use more power and so it may be worthwhile switching to Powersave or Ondemand when not doing audio work. It has been noticed that audio glitches sometimes happen when the CPU changes speed, in particular when the CPU switches to a lower speed.
• Intel Boost: While it would seem like a great idea to be able to run a little faster when the CPU is able, the same problem arises when the CPU switches back down to the rated speed, the audio may glitch. Turning Intel Boost off while doing audio work gives the best audio stability.
• Logging level: Studio Controls has a background process called Autojack that runs from session start to session end. It is the real workhorse in Studio Controls, the GUI is just a front end for this process. Autojack has a logging facility and the logging level determines how much autojack writes to it's log file. If sending a bug report about Studio Controls, attaching a logfile with the logging level set to Extra may be helpful for debugging purposes. The log file may be found at: ~/.log/autojack.log

• FireWire Module select: Chooses the kernel modules to use for FireWire devices. There are the FFADO modules and the newer ALSA Firewire modules (the ALSA firewire modules are based on the FFADO modules). The ALSA modules are easier to use and only work with JACK's ALSA back end. However, there are some Firewire devices that do not have working ALSA modules and work better with the FFADO modules. The FFADO modules also give sample accurate MIDI input and output. Once a change has been made to this setting, A reboot is required to make the new setting available to JACK.

  The author has an AudioFire 12 and has found that while the ALSA modules work fine for most work, The lowest latency on this device using the ALSA firewire modules was setting JACK to 256/2, while when using the FFADO modules, it was easy to set the latency to 32/2 and experience only 1 xrun over 4 hours. So the FFADO modules give lower latency and better stability, at least for this setup.

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