Logic Pro X - #63 - Mixing (part5): Compressor, Expander, and Enveloper on Drums - YouTube
Tesira EX-LOGIC (Tesira PoE logic expander with 16 logic GPIO (4 GPIO are configurable for potentiometer interface)) - Meta-Tech Solutions and Systems Corp.
Expander in Logic Pro - Apple Support (DE)
Logic Pro Expander(エクスパンダ)の使い方 -
Logic Pro 9 Tutorial - Noise Floor Reduction with Expander - YouTube