LA Audio GCX20 - Manual (Page 7)

Page 7
The GCX20 side chain connectors are wired as follows -
Sleeve
Screen Ring
Send
Tip
Return
Plugging into the GCX20's side chain automatically breaks the signal path
to the side chain circuitry. This path must be completed by the external
connected equipment.
The side chain in-out signal path affects both the Compressor and the
Gate response.