Audacity creating noise spikes in captured audios

Hello All,
I have used Audacity a long time and love it. I am trying something new I did not know it was capable of. I am connecting to X32 Behringer digital mixer using a usb connection. I setup by selecting the x32 as an input and using 16 channels for capture. It looked good and I was excited that I could do this, but I noticed that I was getting huge 100 % noise spikes intermittently through through out all channels. We have used the same capture technique on a different windows program with no noise spikes.

Any ideas as to what is causing this? I even changed the priority to high, in case they system was running too slow, no change.

I am Running Ubuntu 15.10, 6 Processors, 6 GB RAM, and running the USB connection through the USB 3 connector for max through-put.

All channels receive the spike at the same time.

Ubuntu 15.10
6 Processors
USB 3 port
Nothing else is running during the capture period
All the latest updates for Ubuntu 15.10
Audacity 2.1.3 daily build

Thanks in advance for any and all help.


It’s probably not relevant to the problem, but alpha builds are for testing, not production work.

Are you choosing the (hw) input for the device in Device Toolbar, so that you are accessing the hardware directly through ALSA?

Please attach an example of the noise spike in WAV (select one channel and export selected audio). Please see here for how to attach files:


Hello Gale,
I rebooted Ubuntu and moved the usb from 3.0 to 2.0 and the spike issue, except at the very beginning are all gone. Not sure why using the usb 3.0 caused the issue, but the problem is now gone. Ran a 70 minute capture with only the initial spike when I started it.

Thanks for getting back with me


A USB 1.1 or 2.0 device will of course only work at that speed even if connected to a USB 3.0 port.

Reboots are good for USB recording devices.

If the problem does come back even after rebooting, please attach an example.