QSC LF-3115, LF-4315 User Manual

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Cinema Loudspeaker Systems User Manual

LF-3115 Low Frequency Loudspeaker

Introduction

The LF-3115 15” (381mm) low frequency enclosure is designed specifically for cinema appli­cations. Meeting cinema requirements for extended low frequency response differentiates
the LF-3115 from more conventional “rock-and-roll” woofer systems. The LF-3115 covers the
frequency range from 33 Hertz to 1900 Hertz, depending upon the high frequency system
requirements.

The 300 watt, 15” transducer is well suited for cinema use. It features a 3” (76mm) voice
coil, ceramic magnet, and a multi-vented pole piece to ensure cool operation. Cooler temper­atures increase transducer lifespan and decrease the problem of power compression at high
power levels. The suspension and voice coil of the transducer 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 stiffen­ing 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. The stiffening
braces reduce panel resonance.

Bass ports are evenly spaced on each side of the transducer, 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.

Mounting points for

high frequency system

Three T-nuts in the top of the enclosure provide easy mounting of QSC high frequency sys­tems, such as the HF-63.

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 perma­nently 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, accesso­ries, 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 installa­tion.

*TD-000172-00*

“QSC” and the QSC logo are registered with the U.S. Pa tent and Trademark Office

QSC® is a registered trademark of QSC Audio Products, Inc.

© Copyright 2004, QSC Audio Products, Inc.

TD-000172-00 rev.B

Connections

Normal Connection

The LF-3115 has barrier strip screw termi­nals for connection. The terminals accept
up to #10 AWG (5.3mm

2

) stranded loud­speaker wiring. Use the largest wire size
and shortest wire length possible for a
given installation. Observe the polarity
markings and keep polarity consistent
throughout the system for best perfor­mance.

Normal Connection Example:

Amplifier capable of
driving 8 ohm loads

Parallel Connection of Second LF-3115

The terminals marked OUTPUT may be
used to connect another LF-3115 in paral­lel. Connect the wires as shown in the illus­tration, at right.

Parallel Connection Example:

Amplifier capable of
driving 4 ohm loads