Materials of construction Kapton coil former for increased rigidity and thermal protection Polyamide-imide coated two-layer aluminium voice coil for lower mass and increased sensitivity Ferrite magnet Vented core for increased power handling Premium pressed steel basket for maximum strength Paper cone Cloth cone edge Solid composition paper dust cap For all high power bass applications including bass guitar. Eminence Model No.Delta 15Nominal Chassis Diameter 15 381mmImpedance 8Omega Power Rating400WrmsResonance40HzUsableFrequency Range40Hz to 4kHzAverage Sensitivity 1W 1m101dBMagnetWeight56oz.Magnet Gap Depth0.375 9.52mmVoice Coil Diameter2.5 63.5mmMounting InformationOverall Diameter15.15 384.8mmBaffle Hole Diameter13.77 349.6mmFront Sealing Gasketfitted as standardRear Sealing Gasketfitted as standardFixing Holes Diameter 8 off0.25 6.4mmFixing Hole P.C.D.14.56 369.9mmDepth6.05 153.6mmWeight12lbs 5.48kgShipping Weight14.6lbs 6.6kgThiele-SmallParametersResonant Frequency fs40HzImpedance Re6.9OmegaCoil Inductance Le0.86mHElectromagnetic Q Qes0.54MechanicalQ Qms6.56Total Q Qts0.49Compliance Equivalent Volume Vas293 litres10.4 cu.ftPeak Diaphragm Displacement Volume Vd231ccMechanical Compliance of Suspension Cms0.28mmNBL Product BL13.6 T-MDiaphragm Mass inc. Airload Mms55 gramsEquiv. Resistance of Mechanical SuspensionLoss Rms2.12NsecMEfficiency Bandwidth Product EBP77Voice Coil Overhang Xmax2.7mmSurface Area of Cone Sd856.3cmsup2supImpedance atResonance Zmax52Omega