Free Air Resonance (Fs): 46.0 Hz Electrical “Q” (Qes): 0.860 Mechanical “Q” (Qms): 10.690 Total Speaker “Q” (Qts): 0.796 Equivalent Compliance (Vas): 0.91 cu. ft. / 25.75 liters One-way, Linear Excursion (Xmax)*: 0.52 in. / 13.2 mm Reference Efficiency (no): 0.28% Efficiency (1W/1m)**: 86.7 dB SPL Effective Piston Area (Sd): 50.11 sq. in. / 0.0323 sq. m. DC Resistance (Re)***: 4.17 ohm Nominal Impedance (Znom): 4 ohm Continuous Power Handling (Pt): 150W