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*TD-000141-00*

Cinema Loudspeaker Systems User Manual

LF-4215

 and

 LF-4215-8 

Low Frequency Loudspeakers

Introduction

The LF-4215 dual 15” (381mm) low frequency enclosure is designed specifically for cinema 
applications. Meeting cinema requirements for extended low frequency response differentiates 
the LF-4215 from more conventional “rock-and-roll” woofer systems. The LF-4215 covers the 
frequency range from 35 Hertz to 1000 Hertz, depending upon the high frequency system 
requirements. Close Coupled Woofers (CCW), with its tight spacing between woofers, improves 
coupling and keeps coverage angles wide over a greater frequency range than more widely 
spaced designs. The LF-4215-8 is an 8 ohm version of the standard 4 ohm LF-4215.

The two custom 400 watt, 15” transducers were developed especially for cinema use. They fea-
ture extremely large 4” (100mm) voice coils and a multi-vented pole piece to ensure cool opera-
tion, even at high power levels. Cooler temperatures increase transducer lifespan and decrease 
the problem of power compression at high power. An undercut pole piece ensures the voice coil 
operates in a Symmetrical Magnetic Gap (SMG), reducing second harmonic distortion.

The enclosure is constructed of high quality MDF panels and features Single Woofer Chambers 
(SWC, separate chambers for each transducer). In the rare event of a transducer failure, this 
prevents over-excursion of the remaining transducer caused by improper box loading. 

Large, Fully Radiused Ports (FRP) ensure smooth air flow through the ports, especially at higher 
power. 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 forces, reducing 
the chance of driving the voice coil out of the center of the gap at high power.

Three T-nuts in the top of the enclosure provide easy mounting of QSC’s HF-75 high frequency 
system, or MH-1075 mid-high system.

Enclosure is not designed to be suspended, flown, or rigged. Do not suspend, 
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 lis-
tening 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, accessories, or brack-
ets specified by QSC Audio Products, Inc. Refer all servicing to qualified per-
sonnel. 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 hard-
ware which is rated for the loading conditions of the installation and any pos-
sible 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 installation.

TD-000141-00 rev.E

© Copyright 2003, 2004, 2007, 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

Summary of Contents for LF-4215

Page 1: ... from being displaced to one side or another by unbalanced forces reducing the chance of driving the voice coil out of the center of the gap at high power Three T nuts in the top of the enclosure provide easy mounting of QSC s HF 75 high frequency system or MH 1075 mid high system Enclosure is not designed to be suspended flown or rigged Do not suspend fly or rig this enclosure This product is cap...

Page 2: ...ay not function If this is the case remove the terminal cup and verify the presence of the factory yellow jumper and blue jumper wires remedy as required or have the loudspeaker serviced Individual Transducer Connection requires modification CAUTION Requires removal of terminal cup and cutting of both the yellow and the blue jumper wires that connect the SPK1 and SPK2 terminals The transducers are...

Page 3: ...r frequency is 1000 Hertz QSC DSP configurations are available at www qscaudio com Parameters for alternative processing hardware are available upon request Connectors Barrier strip screw terminals accept up to 10 AWG stranded wire Four terminals two INPUT and two PARALLEL OUT Drivers are internally wired in parallel For independent transducer connection remove blue jumper wire and yel low jumper ...

Page 4: ...legal rights This limited warranty is freely transferable during the term of the warranty period Customer may have additional rights which vary from state to state In the event that this product was manufactured for export and sale outside of the United States or its territories then this lim ited warranty shall not apply Removal of the serial number on this product or purchase of this product fro...

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