24S, 24S-D, 21S-SUB loudspeakers from d&b audiotechnik GmbH & Co. KG on Vimeo.
The 21S-SUB is a high performance subwoofer for use with the xS-Series and xA-Series loudspeakers and is intended for a wide range of permanently installed applications. The cabinet houses a single long excursion 21" driver in a bass-reflex design. The large, specially shaped reflex port enables the 21S-SUB to achieve high Sound Pressure Levels from a cabinet with a small footprint. When operated in INFRA mode, the 21S-SUB can be used to complement other d&b subwoofers by extending the frequency response of the system down to 33Hz. The 21S-SUB can be ground stacked or flown in either orientation. It can be flown individually or in a cluster of two cabinets. The enclosure is constructed from marine plywood with an impact resistant black paint finish. The front of the loudspeaker cabinet is protected by a rigid metal grill backed by an acoustically transparent foam. The top, bottom and rear panels each incorporate a pair of M10 threaded inserts for attaching d&b rigging hardware. The Weather Resistant (WR) option provides an IP55 rating that enables the operation of loudspeakers in changing ambient conditions, and features a fixed cable.
The d&b 30D amplifier is recommended to drive the 21S-SUB. The d&b D20 and D80 can also be used.
Frequency response (-5 dB standard)
35 - 105 Hz
Frequency response (–5 dB INFRA mode)
33 - 85 Hz
Max. sound pressure1
Cabinets per amplifier channel
Installation specific high performance subwoofer with compact footprint
Power handling capacity (RMS/peak 10 ms)
21" driver with neodymium magnet
1 x NL4
1 x screw terminal block
Dimensions / weight
Dimensions (H x W x D)
1100 x 580 x 526 mm
43.3 x 22.8 x 20.7"
1 1 m, free field, SPL max peak test signal: pink noise with crest factor 4