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*TD-000177-00*
Cinema Loudspeaker Systems User Manual
LF-4315 Low Frequency Loudspeaker
Introduction
The LF-4315 15” (381mm) low frequency enclosure is designed specifically for cinema appli-
cations. Meeting cinema requirements for extended low frequency response differentiates
the LF-4315 from more conventional “rock-and-roll” woofer systems. The LF-4315 covers the
frequency range from 30 Hertz to 500 Hertz, depending upon the high frequency system
requirements.
The three custom 400 watt, 15” transducers were developed specifically for cinema use.
They feature 4” (100mm) voice coils, 120 oz.(3.4kg) ceramic magnets, and multi-vented pole
pieces to ensure cool operation. Cooler temperatures increase transducer lifespan and
decrease power compression at high power levels. Undercut pole pieces ensure the voice
coils operate in symmetrical magnetic gaps, reducing second order harmonic distortion. The
suspension and voice coils of the transducers have been designed to provide low distortion
and high impact bass at high power.
The enclosure is constructed of high quality medium density fiberboard panels with stiffen-
ing braces on all panels. Both internal and external port openings are fully radiused ensuring
smooth air flow at higher power levels, preventing audible port turbulence.
Bass ports are symmetrically spaced on each side of the transducers, making internal pres-
sure more uniform across the back surface of the transducers. This prevents the cones from
being displaced to one side or another by unbalanced forces, reducing the chance of driving
the voice coils out of the center of the gaps at high power.
Three T-nuts in the top of the enclosure provide easy mounting of QSC’s HF-75 high fre-
quency system, or MH-1075 mid-high 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-000177-00 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
high or mid-high
system