Midwoofer PAC SB-Acoustics 4" SB12PAC25-4 Aluminium Speaker

Features
Vented reinforced plastic chassis
Anodised aluminium cone
Low damping rubber surround
Large vented motor system
Long stroke linear suspension
Light weight CCAW voice coil
Non-conducting fibreglass coil former
Non-resonant long life lead wires

Specs
Nominal Impedance 4 Ω
DC resistance, Re 3.1 Ω
Voice coil inductance, Le 0.25 mH
Effective piston area, Sd 50 cm2
Voice coil diameter 25.4 mm
Voice coil height 15 mm
Air gap height 5 mm
Linear coil travel (p-p) 10 mm
Magnetic flux density 1.03 T
Magnet weight 0.40 kg
Net weight 0.86 kg
Free air resonance, Fs 52.5 Hz
Sensitivity (2.83 V / 1 m) 87 dB
Mechanical Q-factor, Qms 5.0
Electrical Q-factor, Qes 0.33
Total Q-factor, Qts 0.31
Moving mass incl. air, Mms 6.1 g
Force factor, Bl 4.35 Tm
Equivalent volume, VAS 5.3 liters
Compliance, Cms 1.50 mm/N
Mechanical loss, Rms 0.4 kg/s
Rated power handling* 30 W
* IEC 268-5, T/S parameters measured on drive units that are broken in.