Architectural specifications

The loudspeaker shall consist of a single 21" long excursion low frequency neodymium driver in bass-reflex design.
The loudspeaker shall only be operated by a dedicated, compatible controller amplifier.
The cabinet enclosure shall be made from marine plywood with an impact resistant black paint finish.
Special colours according to RAL table and a weather resistant option shall be available upon request.
The drivers shall be protected by a rigid metal grill backed by an acoustically transparent foam.
Four rubber feet shall be incorporated in the bottom panel to prevent the cabinet from movement and four corresponding recesses in the top panel shall be incorporated to prevent movement of stacked cabinets.
The cabinet shall incorporate two M10 threaded inserts on the top, bottom and side panels for the secure attachment of dedicated mounting brackets.
The connection panel on the back shall be recessed and fitted with one speakon NL4 M socket and a two pole screw terminal block. A cover plate for protection of the connection panel shall be included.
The loudspeaker shall only be operated by a dedicated, compatible controller amplifier.
The power handling capacity shall be 650 W RMS and 2600 W peak (10 ms). The frequency response (–5 dB) measured on axis shall be 35 Hz to 105 Hz with a maximum sound pressure of at least 135 dB.
The dimensions (W x H x D) shall not exceed 580 x 1100 x 526 mm (22.8" x 43.3" x 20.7") and shall weigh no more than 54 kg (119 lb).

The loudspeaker shall be the 21S-SUB by: d&b audiotechnik GmbH & Co. KG.