Work with plug-in latencies in Logic Pro

Some effect and instrument plug-ins may cause small timing delays, known as latency, when processing audio. Audio processing may cause input latency, output latency, or both. For example, playing a software instrument in Logic Pro incurs only an output latency because the instrument’s audio is generated by the application. However, monitoring an audio recording may have both an input and an output latency because the signal must be input into Logic Pro before it can be processed. Input latency (if any) is added to the output latency, resulting in an overall monitoring latency. Each further process—such as the use of insert effects, for example—may also add to the overall monitoring latency. However, Logic Pro can compensate for these latencies using plug-in latency compensation, ensuring that all your audio output is perfectly synchronized.

You can turn plug-in latency compensation on or off. When plug-in latency compensation is turned on, there can be a slight lag between the moment you start playback and the moment when output begins, depending on how much latency is being compensated.

Logic Pro offers two types of plug-in latency compensation. If you insert latency-causing plug-ins only on audio and instrument channel strips, you can choose plug-in latency compensation for only audio and instrument tracks. Logic Pro achieves this by pre-delaying audio and MIDI regions on audio and instrument tracks. This results in snappy playback response. If you have inserted latency-causing plug-ins on auxillary and/or output channel strips, you can choose plug-in latency compensation for all types of channel strips. When this setting is turned on, Logic Pro compensates for latency-causing plug-ins by calculating the amount of latency caused by all plug-ins, and then delaying all audio streams that do not pass through those aux and/or output channel strips by an appropriate amount. This type of plug-in latency compensation can result in a slight lag in playback response, depending on how much latency is being compensated.

If you use latency-causing plug-ins, it’s best to use them only after you have finished recording. Delays in playing back audio, whether caused by a plug-in or by the plug-in latency compensation feature, can result in your performance being out of time. However, if you find that you need to do additional recording after you have inserted latency-causing plug-ins into your mix, you can activate Low Latency mode, which will route your audio around any latency-causing plug-ins, so that the recorded audio isn’t delayed.

To determine whether a plug-in causes latency, see that plug-in’s documentation.

Turn on plug-in latency compensation

In Logic Pro, choose one of the following options from the Compensation pop-up menu in Logic Pro > Preferences > Audio > General:
- Audio and Software Instrument Tracks: If you have inserted latency-causing plug-ins only into audio and/or instrument channel strips, choose this option. Logic Pro automatically shifts audio and MIDI regions in time to keep all the output synchronized.
- All: If you have inserted latency-causing plug-ins into aux or output channel strips, choose this option. Logic Pro delays all audio streams by an appropriate amount to keep them all synchronized with each other.

Plug-in latency compensation is only available when Show Advanced Tools is selected in Logic Pro > Preferences > Advanced.

Turn on Low Latency Mode

In Logic Pro, do one of the following:

Click the Low Latency Mode button in the control bar.
Note: The Low Latency Mode button does not appear in the control bar by default. To add this button to the control bar, see Customize the Logic Pro control bar.
Select the Low Latency Mode checkbox in Logic Pro > Preferences > Audio > General.

Recorded audio is routed around any latency-causing plug-ins in the signal path. This ensures that the maximum delay that can occur across the signal flow (that is, across the entirety of the current track’s signal path) is less than the latency vaue you set using the Limit slider in Logic Pro > Preferences > Audio > General.

The sound may change when you turn on Low Latency mode. Depending on the plug-ins in use, the change in sound can be anything from subtle to dramatic. If plug-ins being used do not exceed the total latency limit, there is no audible difference.

Low Latency Mode is only available when Show Advanced Tools is selected in Logic Pro > Preferences > Advanced.

Helpful?

Logic Pro User Guide

Work with plug-in latencies in Logic Pro

Turn on plug-in latency compensation

Turn on Low Latency Mode