Logic Pro iPad track sync and panning issues

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Level 1

24 points

Logic Pro iPad track sync and panning issues

First song using Logic Pro/iPad - long time GB/iPad user. Created song with MIDI and audio tracks in GB, then imported into Logic Pro/iPad - worked great. After adding more audio tracks, fx, and editing (over a few days), when I start playback from beginning sometimes the vocal (audio) stacked tracks are out of sync with rest (about 1 beat early). After restarting from beginning, it usually gets back in sync. Also, when exporting, sometimes the first export results in m4a file with same issue, and re-exporting usually works (vocal stack back in sync). In addition, the export seems to swap Left/right panning occasionally and re-exporting usually swaps it back to correct left/right pan.

with Logic Pro/iPad being so new I’m not sure if I’m missing some setting, or if this is a bug…

anyone else experience this?

iPad Pro

Posted on Jun 13, 2023 6:10 AM

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Answer 1

Best reply

Ardenne

Level 1

23 points

Jun 14, 2023 11:21 PM in response to Greggbhill

Interesting observation with the Q3.

You can try using the standard Logic Pro compressor. It has a sidechain input that will be able to serve as a suitable test case.

Try side chaining this compressor from a track with a strong kick drum. Just be sure to change the threshold setting until you see the compressor start to pump. This will have the added effect of giving you a sense how accurate the timing is.

It is a stretch, you may also want to check your delay compensation and/or input monitoring preferences to eliminate all timing related settings as a possible root cause.

As it is unclear which iPad rev you are running, changing your sample rate (to a lower value) and/or audio buffer size setting (to a larger value) may also impact this sense of timing.

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Answer 2

Greggbhill Author

Level 1

24 points

Jun 14, 2023 5:03 PM in response to Greggbhill

I narrowed this down to using a FabFilter Pro-Q3 with sidechain input. If I set sidechain to none, close project, reopen, start playback it is in sync. If I set sidechain to an audio channel or a bus (with audio channels), close project, start playback it is out of sync first playback. Second and subsequent playbacks are in sync.

is this an issue with the plug-in? Are there any apple plugins that have sidechain input I can try?

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Answer 3

Greggbhill Author

Level 1

24 points

Jun 15, 2023 9:12 AM in response to Ardenne

@Ardenne, Thanks for the tip! So when I add the Logic Pro compressor, and point sidechain at same bus as Q3 (Q3 is turned off), I get no sync issue. I set threshold such that you could see/hear the pumping. If I turn Logic compressor off and Q3 on, the sync issue occurs. The interesting thing is, the sync problem only happens on first playback after opening song file, or first time after turning Q3 on. Subsequent playbacks are in sync as if there is something “warming up”, but even waiting 30 seconds after opening before playback has issue. Something about the initial playback after opening song - maybe a buffer isn’t being cleared? And same for export: initial export after opening song the resulting m4a has the sync issue, but re-exporting results in no issue. I guess I need to check with FabFilter support

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Logic Pro iPad track sync and panning issues

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