S 21i is a compact, high-performance passive subwoofer for fixed installations, designed to complement our FR-X, ARES 8 and ARES 12 series in theatres, houses of worship, live music venues, stadiums, and other sound reinforcement applications.

S 21i houses a long excursion 21″ neodymium driver and combines front diffusion, bass reflex and transmission line design for maximum efficiency and outstanding SPL.

Deployed standalone, stacked, or flown, S 21i adapts to mirror the needs of the venue and offers huge space and weight savings compared to industry-standard 2×18” subs.

S 21i is built with pride in Belgium and coated in tough, weather-resistant polyurea to safeguard your investment. The cabinet front is protected by a rigid metal grill, backed by acoustically transparent foam.

S 21i can be quickly deployed in any configuration, including cardioid and end-fire, when used with AUDIOFOCUS A Series amplifiers. Armonia presets are also available for Powersoft amplifiers.


58,8 kg
28 Hz - 100 Hz
8 Ohms
Radiation direct bass-reflex
Omni 360°
M8 threated inserts
Config cardio possible
Made in Belgium




Tech S21i

Technical Sheet S21i

Preset S21

Preset S21 for Powersoft


Preset S21 for AudioFocus A Series

A Chart

A Serie Output Chart