Use effects on the master track in GarageBand on Mac
The master track includes effects that shape the sound of the overall project. You can add, edit, reorder, and remove effects on the master track the same way as on other tracks. You view the effects on the master track by clicking the Master button in the Smart Controls menu bar.
When Master is selected in the Smart Controls menu bar, the effects on the master track are available in three sections:
Effects: Includes Master Echo and Master Reverb, and can also include reverbs used on tracks.
Output: Can include a compressor, limiter, EQ, and other effects.
EQ: A visual equalizer that shapes the overall sound of the project.
The master track includes Master Echo and Master Reverb effects. You can change the setting for the Master Echo and Master Reverb in the Effects pane when the master track is selected. Each audio and software instrument track includes a Master Echo and Master Reverb slider, which you use to control the amount of Master Echo and Master Reverb used on the track.
If a track contains shared reverbs (usually controlled by the Ambience and Reverb screen controls), the shared reverbs appear below the Master Echo and Master Reverb settings in the Master Effects upper pop-up menu, and a slider and checkbox appear below the pop-up when one of the shared reverbs is chosen.