If you see an audio and MIDI sync alert in Logic Pro for Mac
Find out what to do if you see "Error while trying to synchronise Audio and MIDI" in Logic Pro.
This alert appears when the sample rate of an incoming audio signal doesn't match the project's sample rate or if the sample rate fluctuates. It appears most often when using an external audio interface, an external sync device or plug-ins.
Follow the recommendations in this article to prevent the alert from interrupting your session. After each recommendation, try playing your project again to check if the alert still appears. If the alert does still appear, try the next recommendation until the alert stops appearing.
Check sample rate settings
When using an external audio interface with Logic Pro, the sample rate for your interface should adjust automatically to match the sample rate of your project. Sometimes, however, sample rate settings may not match. Check that the sample rate settings match.
Check the sample rate on your external interface
Most external audio interfaces have an application (usually accessible in System Preferences or in the Applications folder) that you can use to view and change hardware settings, including the device's sample rate. See the documentation for your device for more information.
Check the sample rate in Logic Pro
To check your project's sample rate, choose File > Project Settings > Audio. If your project's sample rate doesn't match your interface's sample rate, select the correct sample rate from the Sample Rate pop-up menu.
If your project's sample rate does match your interface's sample rate, select a different sample rate from the Sample Rate pop-up menu, then set it back to the original sample rate.
Check clock settings on digital devices
If you're using an external audio interface with another digital device connected to it, make sure that only one interface is the main clock source. See the documentation for your interface for more information.
Check aggregate device setup
If you're using multiple external audio interfaces combined as an aggregate device
Connect the devices together using word clock, SPDIF, Lightpipe or AES/EBU.
Designate one device as the main clock source.
See the documentation for your interfaces for more information.
Increase the I/O buffer size
To increase the I/O buffer size in Logic Pro, choose Logic Pro > Preferences > Audio, then choose a larger size from the I/O Buffer Size pop-up menu.
Freeze tracks
Freeze any tracks in your project that have plug-ins.
Check sync settings
Check sync settings if you're syncing other applications or devices to Logic Pro, or if you're syncing Logic Pro to another application or device.
When syncing other applications or devices to Logic Pro
When syncing another application or device that can generate MIDI timecode (MTC) or MIDI clock to Logic Pro, turn off "Auto-enable external sync and Tap Tempo". Choose File > Project Settings > Synchronisation, then untick "Auto-enable external sync and Tap Tempo".
When syncing Logic Pro to other applications or devices
When syncing Logic Pro to another application or device using MTC, do the following:
Make sure that the application or device generating MTC isn't also generating MIDI clock. See the documentation for your application or device for more information.
With your Logic Pro project open choose File> Project Settings > Synchronisation, click the Audio tab, then select External or Free from the Core Audio pop-up menu.
Bypass Reaktor Ensemble
If your project includes a software instrument track with a Reaktor Ensemble that syncs its LFO to the song tempo, try bypassing or removing the plug-in from the track.
Use built-in audio
If you're using an external audio interface, try using the built-in audio on your Mac instead of the interface.
Unplug your external audio interface from your Mac.
Open Logic Pro, then choose Logic Pro > Preferences > Audio.
Choose Built-in Output from the Output Device pop-up menu.
Choose Built-in Microphone (or Built-in Input, depending on your computer) from the Input Device pop-up menu.
If alerts aren't appearing, you may need to update or service your audio interface. Contact the manufacturer for support.
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