QSC Audio SB-5218 Speaker User Manual


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Part of the DCS Digital Cinema Speaker Series, QSC’s
SB-5218 and SB-7218 subwoofers offer a unique
solution that addresses the requirements of digital
motion picture soundtracks. Featuring dual 18" low-
frequency transducers mounted in ported enclosures,
these systems extend response to the lowest audible
frequency.
The two custom 18" transducers were developed
especially for cinema use. The woofers feature
4" voice coils and vented pole pieces to ensure
cool operation, even at high power levels. Cooler
temperatures increase driver lifespan and decrease
power compression at high drive levels. Undercut pole
pieces provide a symmetrical magnetic gap, reducing
second harmonic distortion.
Enclosures are constructed of high-quality MDF
panels and feature individual woofer chambers. The
separate chamber for each transducer makes the
enclosure stronger, provides rigidity, and prevents
cone overexcursion in the rare event of a driver failure.
Enclosure “loading” is not lost for the remaining
transducer.
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 on each side of the transducers, 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.
SB-5218/SB-7218
Cinema Subwoofers
Specifications SB-5218 SB-7218
Frequency Range
1
-6 dB half space 24 Hz – 100 Hz 22 Hz – 100 Hz
-10 dB half space 19 Hz – 250 Hz 19 Hz – 250 Hz
Maximum Output
2
Calculated Peak at Rated Power 135 dB 137 dB
Calculated Continuous 129 dB 130 dB
Impedance 4Ω nominal 4Ω nominal
Maximum Input Power
3
100 hours of 6 db crest factor 800 W RMS 1200 W RMS
IEC 268 noise spectrum
2 hours of 6 db crest factor 1000 W RMS 1500 W RMS
pink noise, 50 Hz – 20 kHz,
AES method
Recommended Amplifier Power 1600 W RMS maximum 2600 W RMS maximum
Sensitivity 1 watt /1 meter, 99.5 dB 101 dB
half space
Transducers Two 18" (457 mm) 500 W high Two 18" (457 mm) 700 W high
efficiency subwoofer transducers efficiency subwoofer transducers
featuring 4" (100 mm) copper featuring 4" (100 mm) copper
coils on Kapton formers coils on Kapton formers
Recommended Processing LF boost frequency = 25 Hz, Q = 2.0, Gain = +6 dB provided by QSC,
SF-3 or DCM
Connectors Barrier strip screw terminals accept up to #10 AWG stranded wire
Enclosure B6 alignment, vented enclosure with summetrical port design, tuned to
25 Hz, constructed of MDF and heavily braced. Features vandal resistant
woofer mounting bolts
Dimensions (HWD) 30" x 48" x 24"
(762 mm x 1220 mm x 610 mm)
Weight – Net 205 lb (93 kg) 210 lb (95 kg)
1) All frequency ranges specified refer to measured free field response (half space, 2π).
2) Calculated SPL at 1m, (half space, 2π), speaker operating at rated RMS power with pink noise within specified frequency range.
3) Maximum input power tested in accordance with IEC 268-5 recommendations, 50 Hz – 20 kHz band limiting, 6 dB signal crest factor.
Features
• SB-5218featuresdual500Wtransducers
• SB-7218featuresdual700Wtransducers
• Frequencyrangeextendstobelow25Hzwhenusedwith
thecorrectB6filter
• DCMandSF-3signalprocessorsoptionallyavailable
• Enclosuresfeaturevandal-resistantwoofermountingbolts
• THX™approvedforprofessionalcinemaapplications