Apple Logic Pro X - Manual (Page 186)

Chapter 7 Work with tracks 186
Summing stacks
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.
Subtracks
Main track
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.
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.