L-Acoustics KS21 High Power Compact Subwoofer

KS21 is a compact reference subwoofer designed to extend the bandwidth of A15 and A10 systems. KS21 features one high excursion, direct radiating 21" transducer mounted in a bass-reex tuned enclosure.

KS21 operates from 29 Hz to 60 Hz when associated with A15, or 30 Hz to 100 Hz when associated with A10. KS21 features L-Vents that substantially reduce turbulence and port noise at high levels while also increasing LF eficiency.

The KS21 frequency response is optimized to couple perfectly with both systems. KS21 features a two-point, integrated rigging system that is compatible with A15. Combinations of KS21 and A15 can be flown or stacked to form a full range line source. KS21 also integrates a threaded insert to enable pole-mount configurations of A15 or A10.

KS21 can be deployed in standard or cardioid configurations with dedicated presets, for flown and stacked deployment.

• Deep Bass: Extends system response down to 29 Hz.
• High Output: Delivers a powerful maximum SPL of 138 dB.
• A-Series Match: Designed for seamless rigging and sonic integration with A15 and A10.
• L-Vents: Specialized porting that reduces turbulence and air noise at high volumes.
• Flexible Setup: Supports flown, stacked, and cardioid configurations for precise low-end control.

Low frequency limit (-10 dB)

• 29 Hz (KS21_60 preset)

Maximum SPL

• 138 dB (KS21_100 preset, peak @ 1 m, half-space, CF4 pink noise)

Directivity

• Standard or cardioid configuration (-6 dB nominal)

Transducers

• 1 × 21" neodymium cone driver

Acoustical load

• Bass-reflex design with L-Vents

Nominal impedance

• 8 Ω

Physical & Electrical Connectors

• 2 × 4-point terminal block (push-in connection)

Rigging options

• M6 inserts for rigging plates
• M8 inserts for A-U15i
• 1 × DIN580-compatible M8 threaded insert

Dimensions (H × W × D)

• 764 × 571 × 601 mm (30 × 22.5 × 23.7 in)

Weight (net)

• 49 kg (108 lb)

Cabinet construction

• Premium-grade Baltic beech and birch plywood

Front grille

• Coated steel grille with acoustically neutral 3D fabric

Rigging hardware

• High-grade steel with anti-corrosion coating

Finish

• Dark grey-brown (Pantone 426 C)

Ingress protection

• IP55 rated