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*TD-000149-00*
Cinema Loudspeaker Systems User Manual
HF-75 High Frequency Component
Introduction
The HF-75 is the high frequency component of the SC-412 and SC-422 two-
way, biamplified screen channel loudspeakers for high performance cinema
applications. The system is shipped as two separate components: the HF-75
high frequency system and the LF-4115 or LF-4215 woofer system.
The HF-75 high-frequency system features a large format, 3” (75mm) tita-
nium diaphragm compression driver mounted on a custom designed high-
frequency cinema horn with an adjustable pan and tilt bracket. The horn fea-
tures broad horizontal and vertical coverage angles to ensure coverage of
every seat in the auditorium. The horn is a low-distortion waveguide provid-
ing highly articulate dialogue without the “honky” coloration associated
with conventional horn loudspeakers.
The HF-75 includes a driver protection and equalization network. DC block-
ing capacitors protect against DC or low-frequency signals that would likely
destroy an unprotected driver. Power limiter circuitry protects the driver from
over-powering and a response correction filter smoothes the frequency
response of the horn/driver combination. The driver and equalization net-
work provides for more reliable operation, ensuring the show will go on.
The HF-75 components come pre-assembled to reduce field assembly time.
Three bolts are all that are required to secure the HF-75 to the top of the low
frequency enclosure.
Mounting
Refer to the illustration for mounting information. The HF-75 attaches to the
top of the LF-4115 or LF-4215 with three 5/16-18 bolts, 0.75” long, with lock
washers. We recommend the use of serviceable thread locking compound
when installing the bolts to prevent loosening due to vibration. Aim the horn
in the horizontal plane (pan) before tightening. Adjust the vertical tilt with
the bracket adjustment.
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. Ser-
vicing 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, cab-
inets, 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, profes-
sional engineer when any doubt or questions arise regarding
a physical equipment installation.
TD-000149-00 rev.D
© Copyright 2003, 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
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