BETA- 12A Series Standard American Recommended for professional audio and bass guitar applications as a woofer in a vented enclosure. Also works well for PA in a sealed or bandpass enclosure. SPECIFICATION Nominal Basket Diameter 12", 304.8 mm Nominal Impedance 16 ohms Power Rating Watts 250 W / Music Program 500 W Resonance 47 Hz Usable Frequency Range 43 Hz - 3.8 kHz Sensitivity 98 Magnet Weight 38 oz. Gap Height 0.312", 7.92 mm Voice Coil Diameter 2", 50.8 mm THIELE & Small Parameters Resonant Frequency (fs) 47.1 Hz DC Resistance (Re) 9.81 Ohms Coil Inductance (Le) 1.33 mH Mechanical Q (Qms) 9.05 Electromagnetic Q (Qes) 0.62 Total Q (Qts) 0.58 Compliance Equivalent Volume (Vas) 116.6 liters Peak Diaphragm Displacement Volume (Vd) 128.0 cc Mechanical Compliance of Suspension (Cms) 0.283 mm/N BL Product (BL) 13.75 T-M Diaphragm Mass inc. Airload (Mms) 40.3 grams Efficiency Bandwidth Product (EBP) 76.0 Maximum Linear Excursion (Xmax) 2.37 mm Surface Area of Cone (Sd) 538.9 cm² Maximum Mechanical Limit (Xlim) 11 mm MOUNTING Information Recommended Enclosure Volume Sealed 25.5-35.4 liters, 0.9-1.25 cu.ft. Vented 36.8-139 liters/1.3-4.9 cu.ft. Overall Diameter 12.03", 305.5 mm Baffle Hole Diameter 10.95", 278.1 mm Front Sealing Gasket standard fitted as standard Rear Sealing Gasket standard fitted as standard Mounting Holes Diameter 0.25", 6.4 mm Mounting Holes B.C.D. 11.59", 294.3 mm Depth 4.57", 116 mm