Troubleshooting Cheatsheet: Noise After Bouncing Projects (Logic Pro X)

2023-11-08

Thursday night: so I had checked everything on my mixes. Bounced them one last time in a .WAV file before sending to mastering. Everything sounded fine except… when the masters came back, there was this annoying ongoing noise in the background. I could hear it very distinctly in the first (not-so-silent) seconds of the tracks. Damned, maybe didn’t hear it before because I didn’t worked at a high volume enough. So I opened my Logic Pro sessions and heard… nothing. It was not there either in a .mp3 bounces.

So here it begun, the hunt for some noise that I couldn’t hear in the DAW but was definitely there in the .WAV file.
I spent two hours checking a lot of options, before finally finding the solution. And it was… not coming from the DAW.

This is a checklist of all potential things to go through, found across several forum threads (see list at the end).

Check plug-ins

First, check for an obvious plug-in source (delays, reverb, EQ, etc). In my case, the delay space I was using had a button very conveniently called “noise” that was not set to zero. I couldn’t hear the difference in the DAW, but I figured it would be my best bet.

Check you’re actually listening to the right file

Before moving on, check that you’re actually listening to the newly bounced file and not to an older file in cache. iTunes could do that to you, even if you delete the previous file in your working folder, but you’re bouncing your projet under the same filename (this actually turned out to be my “problem”).

Make sure to either properly purge your Music folder (’unknown albums’ or ‘automatically added music’). But the safest option is to read your files with another software to completely rule this out.

Check Settings

Do some easy checks before moving to the heavier stuff:

When bouncing your project:

set dithering to off
set Normalize to off

In Logic Audio Preferences:

Increase I/O buffer to maximum in the audio preferences
More advanced: check Project Settings > Synchronization > General: Sync Mode should be set to “internal”.

In your project:

Check there isn’t any audio input set to tracking. You can turn the audio input to “none” in the audio preference to make sure of it, just in case.
Check sound is not clipping.

Bounces, bounces

Now we’re moving to more time-consuming checks: this will require to do bounces in an organized way.

Some plug-ins appear to sometimes not react well when bouncing offline, so try bouncing in real time to see if that solves the issue. This won’t allow you to identify the cause, but you’ll get your clean bounce.

Try bouncing in different formats, with different settings: .mp3, then .WAV (24 bits) (in that order).

Dichotomic search

Dichotomic search is time consuming, but it’s radical. It’s your best chance to identify the source of the problem if it comes from an individual track or plug-in.

Bounce with half of the tracks muted. If you can still hear the noise, bounce with half of these tracks muted, and so on until you isolate the noise (or continue with the other half if you can’t hear the noise anymore).

If you want to limit bounces, you can start by exporting all tracks as audio files and check if the noise is there by re-importing them in a new project and applying the dichotomic search by muting half of the tracks.

Once you have isolated the track(s) causing the noise, you can apply the same method to identify the faulty plug-in, by disabling the plug-ins half by half

A few other things to try out if everything else fails

Close and Logic Pro and re-start the machine in case that clears some buffers.
Bounce from a clean project with no plug-in.
Check audio drivers (are they up-to-date?).

References

https://discussions.apple.com/thread/5401720

https://discussions.apple.com/thread/7902000

https://discussions.apple.com/thread/2033691

https://www.logicprohelp.com/forums/topic/81641-noise-after-bouncing-projects-solved/

https://www.reddit.com/r/Logic_Studio/comments/m5p3v5/everything_is_fine_until_i_bounce/