QSC SB-15121 Brochure

Features

• 1500W,21" transducer

• Frequencyrangeextendstobelow25HzwithouttheneedforB6EQfilters

• DCP,DCMandSF-3signalprocessorsoptionallyavailable

SB-15121

21" Cinema Subwoofer

Part of the DCS Digital Cinema Speaker Series,
QSC’s SB-15121 subwoofer offers the highest
performance available for cinema subwoofer
applications. It is designed for use in premiere
cinemas and post-production applications where
the ultimate in performance is required.

The massive 21" low-frequency transducer
features a 6" diameter voice coil in a vented,
neodymium magnet structure that is designed
to dissipate extreme amounts of heat and allow
for excursion that is double that of typical 18"
transducers. This ensures cool operation, even at
high power levels, increases driver lifespan and
decreases power compression at high drive levels.

The large, ported enclosure ensures response to
the lowest audible frequency for bass that you
can not only hear but also feel. The enclosure
is constructed of high quality, heavily braced
MDF Panels. Large, fully radiused ports ensure
smooth airflow, especially at higher drive levels.
This prevents potentially audible port turbulence
noise. Both internal and external port openings
are flared.

With symmetrical port loading, the bass ports are
evenly spaced around the transducer, making
internal pressure more uniform across the back
surface of the woofer. This prevents the cone
from being displaced to one side or another by
unbalanced air pressure, reducing the chance of
driving the voice coil out of the center of the gap
at high drive levels.

Specifications

Frequency Range

-6 dB half space

-10 dB half space

Maximum Output

Calculated Peak at Rated Power

Calculated Continuous

Impedance 4Ω nominal

Maximum Input Power

100 hours of 6 db crest factor

pink noise, 25 Hz – 250 Hz

2 hours of 6 db crest factor

pink noise, 25 Hz – 250 Hz,
AES method

Recommended Amplifier Power

Sensitivity 1 watt /1 meter, half space 99 dB 40 Hz – 100 Hz

Transducer One 21" (533 mm) high efficiency subwoofer transducer featuring a vented

Recommended Processing HPF at 20 Hz, minimum 12 dB / Octave slope

Nominal Coverage Omnidirectional (80 Hz)

Connectors Barrier strip screw terminals accept up to #10 AWG stranded wire. Four

Enclosure Vented enclosure with symmetrical port design, tuned to 25 Hz, constructed

Dimensions (HWD) 48.8" x 30" x 24" (1238 mm x 762 mm x 610 mm) including feet

Weight – Net / Shipping 231 lb (105 kg) / 257 lb (114 kg)

1) All frequency ranges specified refer to measured free field response (half space, 2π).

2) 1 meter, half space, at rated rms power with 6 dB crest factor pink noise input, 40 Hz – 100 Hz.

1

23.8 Hz – 250 Hz

21.5 Hz – 250 Hz

2

137 dB SPL

131 dB SPL

1500 W RMS

2500 W RMS

3400 W RMS maximum / 1200 W RMS minimum

6" (153 mm) copper voice coil on a fiberglass former. High excursion/low
distortion design, with extremely high power handling and low thermal and
port compression. Neodymium magnet to provide a very high force factor
and linear excursion.

terminals; two inputs and two parrallel outputs.

of medium density fibre-board and heavily braced. Features vandal resistant
woofer mounting bolts.

SB-15121

Top

30"

762 mm

Dimensions

24"

610 mm

14.9"

308 mm

5.1"

128 mm

0.8"

19 mm

7.1"

180 mm

48.8"

1238 mm

25.7"

652 mm

SideFront

Specifications subject to change without notice.

©2009 QSC Audio Products, LLC. All rights reserved. QSC and the QSC logo are registered trademarks of QSC Audio Products, LLC in the U.S. Patent and Trademark office
and other countries. All other trademarks are the property of their respective owners. Patents may apply or be pending.

1675 MacArthur Boulevard • Costa Mesa, CA 92626 • Ph: 800/854-4079 or 714/957-7100 • Fax: [phone]

SB-15121 Spec Sheet – 08/24/09

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