*TD-000173-00*
Cinema Loudspeaker Systems User Manual
LF-3215
Low Frequency Loudspeaker
Introduction
The LF-3215 dual 15” (381mm) low frequency enclosure is designed specifically for cinema
applications. Meeting cinema requirements for extended low frequency response differenti-
ates the LF-3215 from more conventional “rock-and-roll” woofer systems. The LF-3215 cov-
ers the frequency range from 32 Hertz to 1500 Hertz, depending upon the high frequency
system requirements. With its tight spacing between woofers, the LF-3215 offers improved
coupling and keeps coverage angles wide over a greater frequency range than more widely
spaced designs.
The 300 watt, 15” transducers are well suited for cinema use. They feature 3” (76mm) voice
coils, 120 oz.(3.4kg) ceramic magnets, and vented pole pieces to ensure cool operation.
Cooler temperatures increase transducer lifespan and decrease the problem of power com-
pression at high power levels. The suspension and voice coil of each transducer have been
designed to provide low distortion and high impact bass at high power levels.
The enclosure is constructed of high quality medium density fiberboard panels with stiffen-
ing braces on all panels and features separate woofer chambers. This prevents over-excur-
sion of a transducer caused by improper box loading in the rare event of a transducer failure.
The eight stiffening braces reduce panel resonance.
Both internal and external port openings are fully radiused ensuring smooth air flow at high
power. This prevents audible port turbulence noise.
With symmetrical port loading, bass ports are evenly spaced on each side of the transduc-
ers, 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 forces, reduc-
ing the chance of driving the voice coil out of the center of the gap at high power levels.
Three T-nuts in the top of the enclosure provide easy mounting of QSC’s HF-63 high fre-
quency system, or MH-1063 mid-high frequency system.
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-000173-00 rev.C
© Copyright 2004, QSC Audio Products, Inc.
QSC® is a registered trademark of QSC Audio Products, Inc.
“QSC” and the QSC logo are registered with the U.S. Patent and Trademark Office
1675 MacArthur Blvd., Costa Mesa, CA, 92626 USA
Main Number (714) 754-6175 Sales & Marketing (714) 957-7100 or toll free (USA only) (800) 854-4079
Customer Service (714) 957-7150 or toll free (USA only) (800) 772-2834
Mounting points for mid-
high or high frequency
system
