What is causing this audio glitch during recording?

Question

I have recorded some voice over using a condensor mic and the Presonus AudioBox iTwo (2-channel interface) into Logic X. The problem is that have found some random pops/clicks in the recordings.

It appears that about 130 or so samples are skipped, but the waveform is not totally disjointed, resulting in a 'muffled' click sound.

It is very inconsistant and intermittent, so it only occurred on one of my recording sessions a few times.

Does anyone know what might be causing this?

A similar problem that might be related: I have had some trouble with switching to the correct sample rate with this interface, and possibly due to the older Mac OS 10.11 System audio. In that instance, sometimes the sample rate 'semi-reverts' with 48/44.1 sample gaps, and needs to be reset.

Once the sample rate is set, as expected I can record some hours of audio. However there are still these apparent sample jumps, as pictured.

Answer 1

Disclaimer : as I don't have the same interface and software as the OP, this answer is based on general information concerning audio on MacOS.

The issue you describe might be caused by an unexpected processor usage peak while recording but given the information you provide, it seems to be a clock or sample rate issue between your audio interface and your DAW software.

You must check that both your software and the audio interface share a common sample rate. While recording, you should also check that the clock is set to the interface clock, and not the PC internal clock.

Step 1 :

Setting the appropriate sample rate and clock on the audio interface can usually be achieved (on MacOS) either by the MacOS Applications/Utilities/Audio and MIDI configuration panel (Sorry, approximate translation as I don't use an English Mac OS). Sometimes, the audio interface can also use a dedicated software for this purpose.

Step 2 :

Depending on your DAW software, when selecting the audio interface as an input for recording, it might either automatically set the project properties according to the audio interface settings, or you might have to do it yourself (setting appropriate sample rate and clock source in the DAW project).

The fact that you have an issue setting the sample rate on Logic might be caused by a sample rate conflict between your audio interface and your DAW software.

EDIT

As the OP mentions, the current specs page for Logic Pro X (June 2018) mentions that :

Minimum System Requirements : macOS 10.12 or later

Running the software under a lower macOS version can lead to unexpected issues. Upgrading to macOS 10.12 might solve the problem.

EDIT august 2018

The OP confirms in a comment that upgrading to High Sierra 10.13.6 solved the issue.