SD-21

• 21" high power woofer
• 1,000 watts RMS
• 30Hz-1.5kHz
• Large 6" voice coil
• High 99dB SPL

Nominal Basket Diameter	21" / 530mm
Impedance	8 ohms
RMS Power Rating	1,000 Watts
Program Power	2,000 Watts
Frequency Response	30Hz - 1.5kHz
Sensitivity (1W/1m)	96.9dB
Voice Coil Diameter	6" / 152.4mm
Voice Coil Material	ALR
Terminal Type	G old Plated Push
Spider Material	Treated Cotton
Former Material	Glass Fiber
Dust Cap	Paper
Basket	Cast Aluminum
Basket Color	Blue
Cone Material	Paper Pulp
Surround Material	Treated Cloth
Magnet Material	Ferrite
Magnet Weight	152.3 oz.
Net Weight	34.4 kg. / 75.68 lbs.
Shipping Weight	40 kg. / 88 lbs.
MOUNTING INFORMATION
Overall Diameter	21.46" / 545mm
Baffle Cutout Diameter	19.25" / 488.2mm
Bolt Circle Diameter	20.47" / 520mm
Overall Depth	9.74" / 247.5mm
Flange Thickness	0.95" / 24mm
No. Of Mounting Holes	8
THIELE-SMALL PARAMETERS
Resonant Frequency (fs)	41 Hz
Impedance (Re)	5.3 ohms
Coil Inductance (Le)	1.4mH
Mechanical Q (Qms)	9.886
Electromagnetic Q (Qes)	.434
Total Q (Qts)	.416
Compliance Equivalent Vol. (Vas)	200.61 Liters/7.08cu. ft.
Voice Coil Overhang (Xmax)	5.9mm
Xmax (Peak to Peak)	31.7mm
BL Factor (BL)	31.72
Surface Area of Cone (Sd)	.173m2
Reference Efficiency	3.08%
Low Frequency Response
Mounting Dimensions