Mackie manual Architects’ and Engineers’ Specifications, SRM450 Block Diagram, Speaker

SPEAKER

SRM450 Active Speaker System

Architects’ and Engineers’ Specifications

SRM450

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.

SRM450 Block Diagram

							THRESHOLD
			LOW CUT	CONTOUR
		J15				HI-PASS
INPUT	2					HI-FREQ	HI-FREQ	TWEET
	3						AMP
	1					COMPRESSOR
THRU	2
	3
		SIGNAL		THERMAL	POWER
	1
		LED		LED	LEDS
		SIGNAL	THERMAL					PEAK
								DETECTION
		SENSE	SWITCH	MUTE	MUTE		MUTE	PEAK
			LOW AC	ON/OFF				LIGHT
	+15VDC		VOLTS SENSE	CONTROL
		TIMED
		TURNOFF
		OFF						LO-FREQUENCY
	SIGNAL					40-120 Hz DELAY LO-PASS COMPRESSOR
	SENSE	ON						DRIVER
		POWER			SWEEPING	176uS
							LO-FREQ
	FUSE	SWITCH			FILTER			WOOF
							AMP

	+	+
	MID VDC	HI VDC	THRESHOLD	LPF	THRESHOLD
	–	–
					BASS CONTROL SERVO LOOP
TOROIDAL POWER	+
TRANSFORMER	–LO VDC				SENSE
					RESISTOR

MACKIE DESIGNS SRM450

BLOCK DIAGRAM (#060322SEDF)

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 accomodate both microphone and line-level signal levels, a sound contour switch providing +3 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 polyproylene 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 Designs SRM450.

Electronic files for this product available at:

www.mackie.com

		This Specification Sheet			SRM450_SS.PDF
		Owner/Operator’s Manual			SRM450_OM.PDF
		CADD files			SRM450.DXF
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