10.6

Table Of Contents
206Logic Pro User Guide
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 the bus 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.
This is similar to the way an audio group works.
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.