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fcpx audio monitoring bug

After some heavy FCPX sessions, we thought it was a good idea to document one of the most annoying bugs with Final Cut Pro X, OS X and external audio. With some amazing timing and help we also found a fix!

FCPX is a slick piece of software no doubt, but it still does have its quirks and bugs. Apple can't test every feature in every editing situation, so hopefully any information fed back to them should help to get rid of bugs. 

One particular problem has been annoying us a lot. Audio monitoring, or lack of it in the browser when deselecting tracks. 

If a clip in the browser has stereo channels, by deselecting the audio in the Inspector to just one channel, lets say the left, the audio is routed out of third party devices as a mono channel (down 3 or 4 we think) and thus you can't hear it.

This is annoying as camera originals fed back over satellite feeds (with a stick mic on one leg and a loud camera mic on the other) can be difficult to monitor in stereo and also it means having to disable the other channels on the timeline every time to hear it.

 stereo mono fcpx


If you have a lot of one-legged interviews then you don't have the choice of being able to set the clip in the browser to the track you want, then continue to edit  laying down each interview with the correct audio.

If you are using the internal speakers with your Mac, you shouldn't experience this issue. It is only with external devices used for monitoring such as an AJA IO 4K or Blackmagic Ultrastudio Express.

Just as we were writing up this article (It actually started off as a bigger bug rant, but we will save that for later) we came across @Vordio's tweet describing exactly the same problem.



Then after a few Twitter exchanges where we both came up with incorrect theories as to why this was happening, Vordio posted a link to this Apple Knowledgebase Article. It was last modified on April 17 2015.

If you can’t monitor mono or dual mono audio from Final Cut Pro X 10.2 in OS X 10.10.3

The good news is that following the instructions, it fixed the issue. We can now listen to a mono track through a stereo output device. Cheers all round and a huge thank you to Vordio for doing the homework.

 Here's what you have to do:

  • Open Audio MIDI Setup.
  • Select your audio output device in the audio device list.
  • Click Configure Speakers in the bottom right of the window.
  • Click Multichannel.
  • Choose Stereo from the pop-up menu and click Done.
  • Where is the Audio MIDI Setup? You'll find it in the Utilities folder within the Applications folder. Once found, this is the page you will need.

    midi stup fcpx


    Ours was already set to stereo, but putting it into 5.1 then back and then selecting 'done' fixed the problem.

    A fix and we are very, very pleased, but this really shouldn't be an issue in the first place. 



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