Alice 538R is a mains-powered, 1U rackmount stereo optical compressor with transformer-balanced left and right inputs and outputs and a dedicated side-chain input. It uses mid/side processing to preserve the stereo image while offering wide, controllable width from mono to well beyond 100%. A hard-wired bypass, dual VU meters, and Attack/Release/Ratio controls accompany an external side-chain, making it a versatile tool for creative dynamics in studios and live systems.