QSC SC-424-8F Owner's Manual

LF-4215-8F

Cinema Loudspeaker User Manual

Low–Frequency Loudspeaker

TD-000295-00-A

*TD-000295-00*

2

IMPORTANT SAFETY PRECAUTIONS AND EXPLANATION OF SYMBOLS

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 or placement. 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 regarding physical equipment installation. Ensure that all local, state and national regulations
regarding the safety and operation of loudspeakers and related equipment are understood and adhered to. This product is capable of
producing sound pressure levels that can permanently damage human hearing. Always keep sound pressure levels in the listening area below
levels that can damage human hearing.

Warranty (USA only; other countries, see your dealer or distributor)

Disclaimer

QSC Audio Products, LLC 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, LLC (”QSC”) guarantees its products to be free from defective material and/or workmanship 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,
one of our authorized service stations or an authorized QSC International Distributor 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. The warranty on QSC products is NOT VALID if the products have been purchased from an
unauthorized dealer/online e-tailer, or if the original factory serial number has been removed, defaced, or replaced in any way. Damage to, or loss of any
software or data residing on the product is not covered. When providing repair or replacement service, QSC will use reasonable efforts to reinstall the
product’s original software configuration and subsequent update releases, but will not provide any recovery or transfer of software or data contained on
the serviced unit not originally included in the product.

Customers may have additional rights, which vary from state to state or from country to country. In the event that a provision of this limited warranty is
void, prohibited or superseded by local laws, the remaining provisions shall remain in effect.

Periodically, this warranty is updated. To obtain the most recent version of QSC’s warranty statement, please visit www.qscaudio.com.

Contact us at 800-854-4079 or visit our website at www.qscaudio.com.

The QSC limited warranty is valid for a period of three (3) years from date of purchase in the United States and many (but not all)
other countries.

For QSC warranty information in countries other than the United States, contact your authorized QSC international distributor. A list of QSC International
distributors is available at www.qscaudio.com.

To register your QSC product online, go to www.qscaudio.com and select ”Product Registration”. Other questions regarding this warranty can be an­swered by calling, e-mailing or contacting your authorized QSC distributor.

© 2009, QSC Audio Products, LLC. Patents may apply or be pending.
QSC is a registered trademark of QSC Audio Products, LLC. “QSC” and the QSC logo are registered with the U.S. Patent and Trademark Office.
All trademarks are the property of their respective owners.

1

Introduction

The LF-4215-8F dual 15" (381 mm) low-frequency enclosure is designed specifically for large format cinema applications. Meeting cinema
requirements for extended low-frequency response differentiates the LF-4215-8F from more conventional “rock-and-roll” woofer systems. The
LF-4215-8F covers the frequency range from 35 Hertz to 1000 Hertz, depending upon the high-frequency system requirements.

The LF-4215-8F is an 8 ohm version of the standard 4 ohm LF-4215 that is designed for safe and easy suspension via M10 fly points. Heavily braced,
tour grade construction provides great strength while keeping weight to a minimum.

The two custom 400 watt, 15" transducers were developed especially for cinema use. They feature extremely large 4" (100 mm) voice coils and a
multi-vented pole piece to ensure cool operation, 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 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 transducers, 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.

Sixteen M10 mounting points provide safe and secure means to suspend the enclosure via M10 forged eyebolts (not included) or user-supplied
brackets. Always consult a licensed structural engineer to approve any mounting method.

Features

• “Flyable” 4–way tri-amplified screen channel speaker system

• Constructed of heavily braced, 15 mm tour-grade plywood

• Sixteen M10 fly points per enclosure for safe and easy suspension

• Common dimensions of Mid/Hi and LF enclosures facilitate easy installation in vertical or horizontal arrays

• Unique HF/VHF diaphragm has less mass than traditional diaphragms resulting in exceptional dynamic range, extended high-frequency response

and lower distortion

• Low-distortion waveguides provide highly articulate dialogue

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4

Suspension

The LF-4215-8F enclosure features 16 load-rated attachment points. As shipped from the factory, each attachment point has a bolt installed to retain
the air-tight design of the enclosure. Never operate the loudspeaker with the attachment points open (unsealed) as it will degrade the performance
of the product.

The LF-4215-8F and MHV-1090F have the exact same external dimensions and attachment points. They can be supported individually or as a pair,
depending on what works best for the application. The boxes can be arrayed vertically and horizontally. When paired together, it is recommended that
the mounting structure connects both boxes to the suspension system rather than suspending the boxes from one another. Commercially available
uni-strut or other custom fabricated brackets can be used.

Suspending the system from the top rear attachment points results in a slight down angle that may be close to the desired aiming for many
installations. The bottom attachment points can be used for a pull-back cable to fine tune the tilt of the system.

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 or
placement. 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 regarding physical equipment installation. Ensure that all local, state and national regulations regarding the
safety and operation of loudspeakers and related equipment are understood and adhered to.

Ensure all attachment points are installed and correctly tightened in order to maintain enclosure’s rated strength. Additionally, air
leaks resulting from missing hardware will degrade the loudspeaker’s performance. Use only QSC’s M10 forged shoulder eye bolts.
Contact QSC Technical Services department for complete information.

M10 Attachment
Points

3

Connections

Normal Connection

Amplifier connections to the LF-4215-8F are made on the rear panel via a Neutrik NL4P SpeakonTM connector supplied by the installer. This connector
provides power to both woofers of the LF-4215-8F via the 1+ and 1- terminals. The woofers are internally wired in parallel. Pre-made Speakon cables
using high grade, 2 or 4 conductor stranded wire are readily available from a number of suppliers and is highly recommended.

MF No Connection

INPUT

PINOUT

1+ 1- 2+ 2-

POS NEG N/A N/A

Specifications

LF-4215-8F

Frequency Range

±3 dB 38 – 1000 Hz

-10 dB 30 – 1200 Hz useable range

Maximum Output 134.5 dB SPL calculated peak

Impedance 8Ω nominal

Maximum Input Power

100 hours of 6 dB crest factor pink
noise, 30 – 500 Hz

2 hours of 6 dB crest factor pink

noise, 30 – 500 Hz, AES method

Sensitivity (half space / watt / 1 meter) 99.5 dB half space, 96.5 dB full space, 35 – 1000 Hz, 1 watt, 1 meter

Transducers

Recommended Processing Subsonic filter below 30 Hz, >18 dB per octave, maximum recommended crossover frequency is

Nominal Coverage 135° horizontal x 50° vertical at 500 Hz

Connectors Neutrik SpeakonTM NL4, LF 1+, 1-, No Connection 2+, 2-

Enclosure Heavily braced 15 mm tour-grade plywood with 16 M10 load-rated attachment points.

800 watts

1000 watts

Two 15" (381 mm) high-efficiency, low-frequency transducers featuring vented 4" (100 mm)
copper voice coils on KaptonTM formers. High-excursion/low-distortion design, with extremely
high-power handling, and low thermal and port compression.

1000 Hz. QSC DSP configurations are available at www.qscaudio.com. Parameters for alternative
processing hardware are available upon request.

Dimensions (HWD)

Weight Shipping 144 lb / 65 kg

Net Weight 134 lb / 61 kg

40" x 31.5" x 19" (1016 mm x 800.1 mm x 482.6 mm)

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6

SPL and Impedance vs. Frequency

SPL 2 Pi (half space)

SPL (dB)

Impedance

Impedance Ohms

Dimensions

31.5"

(800.1 mm)

2 x 3"

(2 x 76.2 mm)

Frequency (Hertz)

2 x 13"

(2 x 330.2 mm)

19"

(482.6 mm)

2 x 37"

(2 x 939.8 mm)

40"

(1016 mm)

2 x 1.5"

2 x 38.1 mm

2 x 28.5"

2 x 723.9 mm

31.5"

800.1 mm

Front Side

5

Top

Mailing Address:

QSC Audio Products, LLC

1675 MacArthur Boulevard

Costa Mesa, CA 92626-1468 USA

Telephone Numbers:

Main Number: [phone]

Sales & Marketing: [phone] or toll free (USA only) [phone]

Customer Service: [phone] or toll free (USA only) [phone]

Facsimile Numbers:

Sales & Marketing FAX: [phone]

Customer Service FAX: [phone]

World Wide Web:

www.qscaudio.com

E-mail:

[e-mail]

[e-mail]

© 2009 QSC Audio Products, LLC. All rights reserved. QSC, and the QSC logo are registered trademarks of QSC Audio Products, LLC in the U.S. Patent and Trademark office and

other countries. Speakon is a trademark of Neutrik. Kapton is a trademark of DuPont. All other trademarks are the property of their respective owners.

Patents may apply or be pending.

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Passionate About Sound