If you see an audio and MIDI sync alert in Logic Pro X

Learn what to do if you see “Error while trying to synchronize Audio and MIDI” when using Logic Pro X.

Logic Pro gives this alert 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 keep the alert from interrupting your session. After each recommendation, try playing back your project to see if the alert still appears. If it does, try the next recommendation until the alert no longer appears.

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 might not match. Check to make sure 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 on your Mac) that lets you 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 a digital device connected to it, make sure to designate only one interface as the master clock. 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, make sure to do the following:

  • Connect the devices together via word clock, SPDIF, Lightpipe, or AES/EBU.
  • Designate one device as the master clock. 

See the documentation for your interfaces for more information.

Increase I/O buffer size

To increase the I/O buffer size in Logic Pro, choose Logic Pro X > Preferences > Audio, then choose a larger size from the I/O Buffer Size pop-up menu.

Freeze tracks

On tracks with plug-ins, try freezing them.

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 Enable Sync in Logic Pro. Choose Project Settings > Synchronization, then uncheck 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 the application or device generating MTC is not also generating MIDI clock. See the documentation for your application or device for more information. 
  • In Logic Pro, choose Project Settings > Synchronization > Audio, 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.

  1. Unplug your external audio interface from your Mac.
  2. Open Logic Pro, then choose Logic Pro > Preferences > Audio.
  3. Choose Built-in Output from the Output Device pop-up menu.
  4. Choose Built-in Microphone (or Built-in Input, depending on your computer) from the Input Device pop-up menu.

If alerts don’t appear, you might need to update or service your audio interface. Contact the manufacturer for support.

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