B 21

B 21 old 3

B 21 is a multi-purpose passive bassreflex subwoofer with high power SE AUDIOTECHNIK 21″ woofer.

Extremely flat frequency response extends down to 25 Hz.

Smart design ensures easy handling and operation in various applications, including cardioid subwoofer stacks.


B 21 old 4

Port design

Aerodynamic port design reduces distortion and airflow noise. The unique asymmetric shape reduces port noise drastically by (-35 dB).

Sockets at front grill

Convenient multiple Neutrik speakON® sockets in front and back allows for easy set up ideal for live performances.
B 21 old 5
B 21 old 6

Octopus feet

The so called “octopus feet” are made from some flexible rubber/plastic material, which provides good slip resistance.

Cardioid subwoofer setups

Due to the intelligent stacking design and the front and rear sockets, it is possible to operate our B-Line subwoofers as a cardioid setup without any problems.
B 21 old 7


B 21 old 8
B 21
Frequency range (-3 dB) *: 33 Hz - 130 Hz
Frequency range (-10 dB)*: 26 Hz - 160 Hz
Coverage (-6dB) [H x V]: Omnidirectional
Nominal impedance 8 Ω
Sensitivity**: 99 dB
Peak power: 4000 W
Continuous power ***: 1000 W
Maximum Peak SPL ****: 142 dB
System type: 1-way passive system
Crossover frequency: -
Transducers: 1 x 21" driver
Enclosure: Vented box
Connectors: Input / Link signal: 4 x Neutrik speakON® NL4
Link output: 1 x Neutrik SpeakON® NL4
Wiring: Pins 1+/1- : driver
Pins 2+/2- : link (Output CH 2, pins 1+/1-)
Product Dimensions [H x W x D] (Including Rigging): 666 x 585 x 832 mm
Net weight: 51 kg
Packaging dimensions [H x W x D]: 796 x 685 x 930 mm
Total weight: 61.5 kg
Cabinet: 15 - 24 mm plywood
Cabinet finishing: Black or white polyurea coating
Grille: Powder coated perforated steel
Hardware: 4 SE Audiotechnik® ergonomic handles
8 rubber feet and top recesses
M20 pole thread
Stacking: -
Splay angles: -
Pole bar: SPS20
Flight case: B21 FC
Transport dolly: B21 TD
Transport cover: B21 TC
All product specifications are subject to change without prior notice. * Measured with a 6th-order Butterworth low-pass filter applied at 130 Hz
** Half space, 1W / 1m, on axis
*** According to EIA-426B Standard (based on RMS Voltage)
**** Max Peak SPL = Sensitivity + 10log10(Continuous Power) + 12 dB Crest Factor

* Half-space (1W / 1m)
** max. SPL peak = Sensitivity + 10 x log10 (RMS Power) + 12 dB Crest Factor
*** Peak Power = Average Power + 6 dB Crest Factor

- All product specifications are subject to change without prior notice. -


B 21 old 9

B 21 Dolly Board

Dolly Board for B 21 subwoofer

B 21 Dolly Board

B 21 old 10

SPS 20

M20 Pole support to mount M-F3A PRO (or M-F3A) on top of our subwoofers

SPS 20


Engineering Data Sheet


EU declaration of conformity - Passive Loudspeakers

EU declaration of conformity - Rigging and Accessories