L-Acoustics | KS21i - Compact subwoofer: 1 x 21" (install)

L-Acoustics | KS21i - Compact subwoofer: 1 x 21" (install)

The L-Acoustics KS21i is the installation version of the KS21: a compact subwoofer with a single high-excursion 21" neodymium driver, designed to bring deep, powerful low end to fixed installations. With its high power-to-size ratio, the KS21i delivers impressive impact where space is limited and aesthetics matter, such as venues, theatres, houses of worship, corporate spaces and entertainment locations.

Designed to extend the A Series install systems

The KS21i is optimised to couple seamlessly with the A15i and A10i install loudspeakers. Together they reinforce the contour of the system and extend the low-frequency bandwidth, while the KS21i can be flown or stacked alongside the A Series to form a full-range line source.

Clean, controlled low end

The bass-reflex enclosure features L-Vents™, laminar ports that significantly reduce turbulence and port noise at high levels while improving low-frequency efficiency. The result is a tight, articulate low end with strong short-term impact, well beyond what you would expect from a subwoofer of this size.

Standard or cardioid configurations

With dedicated presets, the KS21i can be deployed in standard or cardioid configurations, for both flown and stacked setups. A cardioid arrangement reduces low-frequency energy towards the rear, which helps keep unwanted bass out of stages, back-of-house areas and adjacent spaces.

Built for installation

• Premium Baltic birch and beech plywood enclosure
• Coated steel grille for durable protection
• Dedicated external rigging kits for flown or stacked installation
• Connector panel with push-in terminal block, designed for clean installation
• Weather-resistant construction, suited to demanding environments

Part of the L-Acoustics ecosystem

The KS21i is driven and protected exclusively by L-Acoustics amplified controllers with dedicated presets, ensuring consistent performance and seamless integration with your L-Acoustics installation.

• Low frequency limit (-10 dB): 29 Hz (KS21_60)
• Maximum SPL: 138 dB (KS21_100) with LA2Xi (bridge mode) / LA4X / LA8 / LA12X; 131 dB (KS21_100) with LA2Xi
• Nominal directivity (-6 dB): Standard or cardioid configuration
• Transducers: 1 × 21″ neodymium cone driver
• Acoustical load: Bass-reflex, L-Vents
• Nominal impedance: 8 Ω
• Connectors: 1 × 4-point terminal block with push-in connection
• Rigging and handling: External rigging kits; M6 inserts for rigging plates; M8 inserts for A-U15i; 1 DIN580-compatible M8 threaded insert
• Dimensions (H × W × D): 752 × 569 × 629 mm (29.6 × 22.4 × 24.8 in)
• Weight (net): 46 kg (101 lb)
• Cabinet: Premium grade Baltic beech and birch plywood
• Front: Coated steel grill; acoustically neutral 3D fabric
• Finish: Dark grey brown, Pantone 426 C; pure white, RAL 9010; custom RAL code on special order
• IP rating: IP55