Logic Pro X: Track Stacks overview
Track Stacks provide a convenient way to organize and control tracks, to manage projects with high track counts, and to create and manage audio subgroups.
There are two types of Track Stacks: folder stacks and summing stacks. Both types have a main track and one or more subtracks. The track header for the main track features a disclosure triangle that lets you show or hide the subtracks. When you close the stack, only the main track appears in the Tracks area.
Subtracks can include any track type: audio, software instrument (including layered and multi-output software instruments), external MIDI instrument, or aux tracks. Folder stacks can also include summing stacks as subtracks.
Folder stacks let you combine multiple tracks and control them as one unit, without changing the audio routing of the individual subtracks. When you create a folder stack, the channel strip assigned to the main track is called the stack master. Using the main track or the stack master channel strip, you can mute, solo, and adjust the volume level for the folder stack.
Individual subtracks in a folder stack can have Smart Controls, but the main track has no Smart Controls. There are no patches for the main track of a folder stack, and no patch can be saved when the main track is selected.
There are no regions on the main track of a folder stack, only on its subtracks. When the folder stack is closed, the main track displays an overview of the combined contents of all subtracks.
When you mute a folder stack using the Mute button on the main track (or stack master channel strip), the mute or solo state of individual subtracks is preserved, and becomes active again when the main track is unmuted.
Summing stacks let you combine multiple tracks and route their output to an audio subgroup. When you create a summing stack, the outputs from the subtracks are routed to a bus, the destination aux of which is assigned to the main track. When the main track is selected, you can mute, solo, and adjust volume and send levels for the summing stack, and add and edit plug-ins, affecting the sound of all the subtracks in the summing stack.
If a summing stack contains software instrument tracks as subtracks, you can record and play MIDI regions on the main track. MIDI events on the main track are played by all the software instrument subtracks in the summing stack. You can also record and play MIDI regions on individual (software instrument) subtracks. When the summing stack is closed, the main track displays an overview of the combined contents of all subtracks.
When the main track of a summing stack is selected, you can choose a different patch for the summing stack, and create your own patches. Patches for a summing stack can include the main track and all subtracks, along with their channel strip and plug-in settings. Logic Pro includes a set of factory patches designed for use with summing stacks.
The main track of a summing stack, as well as its subtracks, can have Smart Controls. Screen controls for the Smart Control on the main track can be mapped to channel strip or plug-in parameters on any of the subtracks as well as the main track.
For summing stack patches included with Logic Pro, only the main track has a Smart Control layout, which remains visible in the Smart Controls pane when a subtrack is selected. However, summing stack patches you create keep their individual Smart Control layouts for subtracks.
Summing stacks provide a convenient way to work with a multi-output software instrument (MOSI) and its individual outputs as a single unit. This can be used, for example, for programmed drum kits. You can create a summing stack for a MOSI with the MOSI channel strip on the first subtrack, with additional subtracks for the output aux channel strips of the MOSI stack. When you record and edit MIDI regions on the main track, the MIDI events are sent to the subtrack containing the MOSI for playback.
After you create a summing stack, you can route individual subtracks to different destinations. In the Bus submenu of the Send pop-up menu on subtracks, local busses are sorted into stack submenus. Note that if you route subtracks to a destination “outside” of the stack, those subtracks are no longer affected by the controls on the main track. Audio subgroups you create are saved as part of the summing stack, and their auxes appear as the last (bottom) subtracks in the summing stack.
When a Track Stack contains a single software instrument subtrack, that subtrack appears in the left inspector channel strip, and its routing destination (usually the main track aux) appears in the right inspector channel strip when the main track is selected. Similarly, when a Track Stack contains a single audio subtrack (and no software instrument subtracks), that subtrack appears in the left inspector channel strip, and its routing destination (usually the main track aux) appears in the right inspector channel strip when the main track is selected.