SRM450
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5
O F 6 P A G E S
Active Speaker System
Active Speaker System
SRM450
SPEAKER
SRM450
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6
O F 6 P A G E S
LOUD Technologies continually engages in research related to product improvement. New material,
production methods, and design refinements are introduced into existing products without notice as a
routine expression of that philosophy. For this reason, any current LOUD Technologies product may differ
in some respect from its published description, but will always equal or exceed the original design speci-
fications unless otherwise stated. ©1999-2004 LOUD Technologies Inc. All rights reserved. Mackie and
the “Running Man” figure are registered trademarks of LOUD Technologies Inc.
Part No. 091-221-00 Rev. B 09/04
www.mackie.com
16220 Wood-Red Road NE, Woodinville, WA 98072 USA
800.898.3211, fax 425.487.4337, sales@mackie.com
UK
+44.1268.570.808, fax +44.1268.570.809, uk@mackie.com
Active 2-Way Sound
Reinforcement Speaker System
SRM450
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1
O F 6 P A G E S
SRM450
SPEAKER
Electronic files for this product available at:
www.mackie.com
This Specification Sheet SRM450_SS.PDF
Owner/Operator’s Manual SRM450_OM.PDF
The active two-way, full-range loudspeaker system
shall incorporate one 12-inch low-frequency (LF) trans-
ducer and a 1-inch exit/1.75-inch diaphragm compression
driver high-frequency (HF) transducer. The LF driver shall
be mounted in a vented polypropylene molded enclosure
tuned for optimum low-frequency response. The HF trans-
ducer shall be loaded on a multi-cell horn aperture and
mounted on a combination exponential and conical horn.
The system shall have a nominal coverage pattern of
90° (horizontal) x 40° (vertical). System frequency response
shall vary no more than ±3 dB from 55 Hz to 18 kHz
measured on axis. The loudspeaker shall incorporate a
Class G low-frequency amplifier capable of delivering 300
watts rms over a frequency range of 20 Hz-2000 Hz. The
system shall incorporate a Class AB 100 watt rms ampli-
fier specifically designed to power the HF driver over the
range of 1500 Hz-20 kHz. The amplifiers shall be mounted
on an aluminum heatsink, which shall be mounted on the
rear of the speaker system, and shall be convection cooled.
Thermal protection shall be provided by a thermal
sensor mounted on the heatsink, which monitors the
heatsink temperature and triggers the thermal protection
circuit should the temperature exceed 158° F (70° C). The
Thermal LED shall light and the input signal to the ampli-
fiers shall be muted until the heatsink cools to a safe oper-
ating level, at which point the thermal protection circuit
auto-resets and normal operation resumes.
Overload protection for the LF driver shall be provided
by a dynamically variable high-pass filter, the corner fre-
quency of which shall slide from 40 Hz to 120 Hz as the LF
amplifier output approaches clipping. Additional protec-
tion shall be provided for both the LF and HF drivers by a
compressor circuit, which monitors the low-frequency and
high-frequency amplifier outputs and reduces the gain as
the amplifiers approach clipping.
The system shall include an XLR input connector, an
XLR loop-through signal connector, a level control capable
of providing up to 40 dB of gain to accommodate both
microphone and line-level signal levels, a sound contour
switch pro3 dB of equalization at 100 Hz and 12 kHz,
a high-pass switch for filtering out frequencies below 75 Hz,
and a timed turn-off switch for self shut-down.
The loudspeaker enclosure shall have an asymmetrical
trapezoidal shape and shall incorporate 10 integrated
M10 fly points, two side handles, and a top relocation
handle. The enclosure shall be molded from polypropylene
material. The front of the loudspeaker shall be covered with
a powder coated, weather-resistant perforated steel grille.
The active two-way full-range loudspeaker system shall
be a Mackie SRM450.
INPUT
THRU
2
3
1
2
J15
3
1
HI-PASS
LOW CUT
CONTOUR
COMPRESSOR
THRESHOLD
COMPRESSOR
SWEEPING
FILTER
LO-PASS
DELAY
176uS
HI-FREQ
40-120 Hz
LO-FREQUENCY
DRIVER
TWEET
LO-FREQ
AMP
HI-FREQ
AMP
SENSE
RESISTOR
BASS CONTROL SERVO LOOP
WOOF
PEAK
LIGHT
PEAK
DETECTION
MACKIE
SRM450
BLOCK DIAGRAM
(#060322SEDF)
THRESHOLD
LPF
THRESHOLD
+
–
MID VDC
+
–
LO VDC
+
–
HI VDC
TOROIDAL POWER
TRANSFORMER
FUSE
POWER
SWITCH
ON
OFF
+15VDC
SIGNAL
SENSE
SIGNAL
SENSE
MUTE
ON/OFF
CONTROL
MUTE
MUTE
POWER
LEDS
THERMAL
LED
THERMAL
SWITCH
LOW AC
VOLTS SENSE
TIMED
TURNOFF
SIGNAL
LED
SRM450 Block Diagram
Architects’ and Engineers’ Specifications
