SB ACOUSTICS SW26DAC76-8, 27cm ALUMINUM CONE SHALLOW SUBWOOFER 8OHMFeatures Unique patented long through shallow design Vented cast aluminum chassis for optimum strength and low compression Dual rigid aluminum cone structure Non-conducting fiber glass coil former for minimum damping Shorting ring in motor system for reduced distortion Copper voice coil for improved power handling Long life insulated silver lead wires Powerful neodymium motor system Specs Nominal Impedance 8 Ω DC resistance, Re 6.4 Ω Effective piston area, Sd 312 cm2 Voice coil diameter 75.5 mm Voice coil height 30 mm Air gap height 6 mm Linear coil travel (p-p) 24 mm Magnetic flux density 1.0 T Magnet weight 281 g Net weight 3.43 kg Free air resonance, Fs 19.5 Hz Sensitivity (2.83V/1m) 83 dB Mechanical Q-factor, Qms 4.4 Electrical Q-factor, Qes 0.29 Total Q-factor, Qts 0.28 Moving mass incl. air,Mms 172 g Force factor, Bl 21.4 Tm Equivalent volume, Vas 54 ltr. Compliance, Cms 0.39 mm/N Mechanical loss, Rms 4.8 kg/s Rated power handling* 250 W * IEC 268-5, T/S parameters measured on drive units that are broken in.