The Korg A3 Performance Signal Processor is a legendary 1U rackmount digital multi-effects unit released in 1989. It became iconic primarily due to The Edge of U2, who famously used its auto-wah/filter algorithms to create the distinctive guitar tone for the song "Mysterious Ways" and extensively utilized the unit on the Achtung Baby and Zooropa albums.

Core Effect Categories

• Dynamics & Filters: Compressor, Exciter, Auto-Wah, and generic EQs.
• Drive Modules: Overdrive, Hard Distortion, and Tube Emulation.
• Modulation: Stereo Chorus, Flanger, Phaser, Rotary Speaker simulator, Pitch Shifter, and Detune.
• Time & Space: Mono/Stereo/Modulation Delays, Early Reflections, and Room/Hall/Plate Reverbs.

Key Technical Specifications

• Processing: 16-bit digital signal processing with a 4-times oversampling digital filter.
• Effects Architecture: Houses 41 individual effect types.
• Simultaneous Processing: Can string together up to 6 effects simultaneously using 20 fixed connection patterns, known as "effect chains".
• Memory: Features 100 user-programmable RAM slots.
• Interface: A 40-character backlit LCD screen paired with seven dual-function rotary/push-button knobs for fast, hardware-style editing.
• Physical Connections: Front and rear mono inputs, stereo L/R outputs, direct audio output, MIDI In/Out/Thru, and dual footswitch inputs.