Hi,

On 06.09.2012 22:20, louis@museresearch.com wrote:

Hi! I'm attempting to get the "Clock Selector" mixer control to work with the PreSonus AudioBox 1818VSL (a UAC2 device).

The control shows up in amixer as an enumerated value, but I don't seem to be able to set it (I've tried amixer, alsactl, and setting it programmatically). The possible values are correct (listing Internal Clock, S/PDIF Clock, and ADAT Clock as possible options); It just doesn't appear to take my setting, by which I mean amixer doesn't update the settings, I still have the occasional click when the sampling rates match over S/PDIF and I attempt to use external sync. No error is returned.

After digging around USB specs and ALSA's usb/mixer.c and being unfamiliar with both the USB audio spec and the inner workings of ALSA, I thought it'd be best to ask the list about this: How would I check to see if ALSA is asking the device to change clock source at all?

Hmm. A clock selector is handled like any other control entity on the hardware. Some thoughts:

- Are you able to control other settings like the volume?

- It's fairly common for devices to not accept a new clock source setting if they can't lock to the external source within some time. Did you connect anything to the digital inputs?

- Are you able to control that setting with the native Mac OS X driver? (IOW, without installing a 3rd-party driver)

Also, please send the output of "lsusb -v" for that device.

Daniel