QSC Audio SB-5218 - Manual (Page 3)

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*TD-000150-00*
Cinema Loudspeaker Systems User Manual
SB-5218 and SB-7218
Dual-18” Subwoofers
Introduction
The SB-5218 and SB-7218 are specially designed cinema subwoofers, featuring dual 500
and 700 watt, respectively, 18” (460mm) low-frequency transducers mounted in ported
enclosures. The enclosures are tuned to 25 hertz and use a B6 alignment. These should be
used with the B6 boost filter option provided by the QSC SF-1 or SF-3 Subwoofer Filter mod-
ules or the QSC Digital Cinema Monitor to ensure extended response to the lowest audible
frequencies.
Meeting cinema requirements for the extended low frequency response differentiates the
SB-5218 and SB-7218 from more conventional “rock-and-roll” subwoofer systems. Their fre-
quency range extends to below 25 hertz when used with the correct B6 filter.
The two custom 500 watt (700 watt, SB-7218), 18” transducers were developed especially
for cinema use. The woofers feature 4” (100mm) voice coils and vented pole pieces to
ensure cool operation, even at high power levels. Cooler temperatures increase driver
lifespan and decrease problematic power compression at high drive levels. Undercut pole
pieces provides a Symmetrical Magnetic Gap (SMG), reducing second harmonic distortion.
Enclosures are constructed of high quality MDF panels and feature Single Woofer Chambers
(SWC). The separate chamber for each transducer makes the enclosure stronger, provides
rigidity, and prevents cone over-excursion in the rare event of a driver failure (enclosure
“loading” is not lost for the remaining transducer).
Large, Fully Radiused Ports (FRP) ensure smooth air flow through the ports, especially at
higher drive levels. This prevents potentially audible port turbulence noise. Both internal and
external port openings are fully radiused.
With Symmetrical Port Loading (SPL) bass ports are evenly spaced on each side of the trans-
ducers, making internal pressure more uniform across the back surface of the transducer.
This prevents the cone from being displaced to one side or another by unbalanced air pres-
sure, reducing the chance of driving the voice coil out of the center of the gap at high drive
levels.
Enclosure is not designed to be suspended, flown, or rigged. Do not sus-
pend, fly, or rig this enclosure.
This product is capable of producing sound pressure levels that can perma-
nently damage human hearing. Always keep sound pressure levels in the
listening area below levels that can damage human hearing.
Install in accordance with QSC Audio Product’s instructions and a
licensed, professional engineer. Only use attachments, mounts, accesso-
ries, or brackets specified by QSC Audio Products, Inc. Refer all servicing
to qualified personnel. Servicing is required when the apparatus has been
damaged in any way.
WARNING! Before placing, installing, rigging, or suspending any speaker
product, inspect all hardware, suspension, cabinets, transducers, brackets
and associated equipment for damage. Any missing, corroded, deformed or
non-load rated component could significantly reduce the strength of the
installation, placement, or array. Any such condition severely reduces the
safety of the installation and should be immediately corrected. Use only
hardware which is rated for the loading conditions of the installation and
any possible short-term unexpected overloading. Never exceed the rating
of the hardware or equipment. Consult a licensed, professional engineer
when any doubt or questions arise regarding a physical equipment installa-
tion.
TD-000150-00 rev.B
© Copyright 2003, 2004, QSC Audio Products, Inc.
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