QSC Audio specifications SB-5218/SB-7218

SB-5218/SB-7218

Cinema Subwoofers

Features

•SB-5218 features dual 500 W transducers

•SB-7218 features dual 700 W transducers

•Frequency range extends to below 25 Hz when used with the correct B6 filter

•DCM and SF-3 signal processors optionally available

•Enclosures feature vandal-resistant woofer mounting bolts

•THX™ approved for professional cinema applications

Part of the DCS Digital Cinema Speaker Series, QSC’s SB-5218 and SB-7218 subwoofers offer a unique solution that addresses the requirements of digital motion picture soundtracks. Featuring dual 18" low- frequency transducers mounted in ported enclosures, these systems extend response to the lowest audible frequency.

The two custom 18" transducers were developed especially for cinema use. The woofers feature 4" voice coils and vented pole pieces to ensure cool operation, even at high power levels. Cooler temperatures increase driver lifespan and decrease power compression at high drive levels. Undercut pole pieces provide a symmetrical magnetic gap, reducing second harmonic distortion.

Enclosures are constructed of high-quality MDF panels and feature individual woofer chambers. The separate chamber for each transducer makes the enclosure stronger, provides rigidity, and prevents cone overexcursion in the rare event of a driver failure. Enclosure “loading” is not lost for the remaining transducer.

Large, fully radiused ports ensure smooth airflow, especially at higher drive levels. This prevents potentially audible port turbulence noise. Both internal and external port openings are flared.

With symmetrical port loading, the bass ports are evenly spaced on each side of the transducers, making internal pressure more uniform across the back surface of the woofer. This prevents the cone from being displaced to one side or another by unbalanced air pressure, reducing the chance of driving the voice coil out of the center of the gap at high drive levels.

THX is a trademark of THX Ltd.

Specifications	SB-5218	SB-7218
Frequency Range1
-6 dB half space	24 Hz - 100 Hz	22 Hz - 100 Hz
-10 dB half space	19 Hz - 250 Hz	19 Hz - 250 Hz
Maximum Output2
Calculated Peak at Rated Power	135 dB	137 dB
Calculated Continuous	129 dB	130 dB
Impedance	4Ω nominal	4Ω nominal
Maximum Input Power3
100 hours of 6 db crest factor	800 W RMS	1200 W RMS
IEC 268 noise spectrum
2 hours of 6 db crest factor	1000 W RMS	1500 W RMS
pink noise, 50 Hz - 20 kHz,
AES method
Recommended Amplifier Power	1600 W RMS maximum	2600 W RMS maximum
Sensitivity 1 watt /1 meter,	99.5 dB	101 dB
half space
Transducers	Two 18" (457 mm) 500 W high	Two 18" (457 mm) 700 W high
	efficiency subwoofer transducers	efficiency subwoofer transducers
	featuring 4" (100 mm) copper	featuring 4" (100 mm) copper
	coils on Kapton formers	coils on Kapton formers
Recommended Processing	LF boost frequency = 25 Hz, Q = 2.0, Gain = +6 dB provided by QSC,
	SF-3 or DCM
Connectors	Barrier strip screw terminals accept up to #10 AWG stranded wire
Enclosure	B6 alignment, vented enclosure with summetrical port design, tuned to
	25 Hz, constructed of MDF and heavily braced. Features vandal resistant
	woofer mounting bolts
Dimensions (HWD)	30" x 48" x 24"
	(762 mm x 1220 mm x 610 mm)
Weight - Net	205 lbs (93 kg)	210 lbs (95 kg)

1)All frequency ranges specified refer to measured free field response (half space, 2π).

2)Calculated SPL at 1m, (half space, 2π), speaker operating at rated RMS power with pink noise within specified frequency range.

3)Maximum input power tested in accordance with IEC 268-5 recommendations, 50 Hz - 20 kHz band limiting, 6 dB signal crest factor.