Click any Insert slot, then navigate to the Mono → Surround (on mono channel strips), Stereo → Surround (on stereo channel strips), or Surround version (on surround channel strips) of the plug-in you want to use.
For example, on a stereo format channel strip, navigate to Delay > Delay Designer > Stereo → 5.1. If the project surround format is set to 7.1, the Plug-in pop-up menu of a stereo channel strip is displayed as follows: Delay > Delay Designer > Stereo → 7.1.
Tip: It’s possible to release the pointer on the plug-in name, instead of navigating all the way through the hierarchy to the channel format. The plug-in opens automatically using the default channel strip format.
In Logic Pro, Option-click a channel strip Insert slot.
The pop-up menu displays all available formats for the plug-in, rather than being limited to the matching channel format. Any downmixing or upmixing that may be necessary will happen automatically.
The default format of software instruments is stereo (if available). Mono and the project surround format are offered as additional formats.
The default format of effect plug-ins is the current channel strip format (at the insert point in the signal path).
All plug-in format variations (based on the current channel strip input format, and all available plug-in output formats) are offered, up to the maximum allowed by the project surround format.
Note: This applies only if the output of the channel strip is already routed to a surround bus or output.
Logic Pro effect plug-ins can also be operated in a multi-mono configuration, based on the project surround format.
Logic Pro automatically performs surround downmixes and upmixes whenever the format of the input and output channels don’t match. For example, if you insert a quadraphonic plug-in into a 5.1 bus, a downmix from 5.1 to Quad, followed by an upmix back to 5.1 occurs automatically.
Download the guides:
Logic Pro User Guide: PDF
Logic Pro Effects: PDF