QSC Audio Portable Speaker LF 4215 User Guide

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  
LF-4215  
and  
Cinema LoudspeakeLr SFys-te4m2s 1Us5er-M8anual  
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.  
Mounting points for high  
or mid-high system  
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*  
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  
 
LF-4215 Specifications (subject to change without notice)  
Frequency Range:  
38 - 1300 Hertz ( 3 dB)  
30 - 1400 Hertz useable range (-10 dB)  
Nominal Coverage:  
Maximum Output:  
100° horizontal X 55° vertical at 600 Hertz  
134.5 dB SPL calculated peak, 1 meter, half space, at rated rms power with 6 dB crest factor pink noise input, 25 - 250 Hertz.  
128.5 dBA SPL calculated maximum continuous, 1 meter. The dBA scale is typically used to identify sound sources  
which can cause permanent hearing loss.  
Impedance:  
4 ohms nominal (8 ohms nominal, LF-4215-8)  
Maximum Input Power:  
800 watts rms (100 hours of 6 dB crest factor pink noise, 30 - 500 Hertz)  
1000 watts rms (2 hours of 6 dB crest factor pink noise, 30 - 500 Hertz, AES method)  
recommended amplifier power capability- 1600 watts rms maximum into 4 ohms (LF-4215) or 8 ohms (LF-4215-8)  
Sensitivity:  
99.5 dB half space, 93.5 dB full space, 35 - 1000 Hertz, 1 watt, 1 meter  
Recommended Processing:  
Subsonic filter below 30 Hertz, >18 dB per octave, maximum recommended crossover frequency is 1000 Hertz. QSC  
upon request.  
Connectors:  
Transducers:  
Enclosure:  
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 wire on internal-side of terminal cup and mark enclosure accordingly.  
Two 15” (381mm) high efficiency low frequency transducers featuring vented 4” (100mm) copper voice coils on Kap-  
ton® formers. High excursion/low distortion design, with extremely high power handling, and low thermal and port  
compression.  
Quasi B4 alignment, ported enclosure with fully flared ports, low turbulence symmetrical port design, tuned to 36  
Hertz, constructed of medium density fibreboard and heavily braced. Features vandal resistant woofer mounting bolts.  
Size:  
30” wide X 35” high X 20” deep (762 mm X 889 mm X 508 mm)  
195 lbs. shipping, 172 lbs. net (88/78 kg.)  
Weight:  
SPL and Impedance vs. Frequency  
SPL 2pi  
SPL 4pi  
LF-4215-8 Impedance  
LF-4215 Impedance  
Frequency (Hertz)  
 
Warranty (USA only; other countries, see your dealer or distributor)  
Disclaimer  
QSC Audio Products, Inc. is not liable for any damage to amplifiers, or any other equipment that is caused by negligence or  
improper installation and/or use of this loudspeaker product.  
QSC Audio Products 3 Year Limited Warranty  
QSC Audio Products, Inc. (“QSC”) guarantees its products to be free from defective material and / or workmanship for a period  
of three (3) years from date of sale, and will replace defective parts and repair malfunctioning products under this warranty  
when the defect occurs under normal installation and use - provided the unit is returned to our factory or one of our authorized  
service stations via pre-paid transportation with a copy of proof of purchase (i.e., sales receipt). This warranty provides that  
the examination of the return product must indicate, in our judgment, a manufacturing defect. This warranty does not extend  
to any product which has been subjected to misuse, neglect, accident, improper installation, or where the date code has been  
removed or defaced. QSC shall not be liable for incidental and/or consequential damages. This warranty gives you specific  
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 from an unauthorized  
dealer, will void this limited warranty. Periodically, this warranty is updated. To obtain the most recent version of QSC’s war-  
Contacting QSC Audio Products  
Mailing address:QSC Audio Products, Inc.  
1675 MacArthur Boulevard  
Costa Mesa, CA 92626-1468 USA  
Telephone Numbers:  
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  
Facsimile Numbers:  
Sales & Marketing Fax(714) 754-6174  
Customer Service Fax(714) 754-6173  
QSC Audio Products, Inc. 1675 MacArthur Boulevard Costa Mesa, California 92626 USA  
©2003, 2004, 2007, “QSC” and the QSC logo are registered with the U.S. Patent and Trademark Office.  
Kapton® is a registered trademark of E.I. du Pont de Nemours and Company.  
 

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