The SB Acoustics SB12PAC25-4 is a 4 inch 4 ohm midwoofer that features a reinforced plastic chassis, a rubber surround and an anodised aluminium cone that offers an extended frequency response with excellent transient response. The SB12PAC25-4 is a high quality feature rich loudspeaker at a sensible price

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
  

Specifications:-

Nominal Impedance                  4 Ohms

DC resistance                     Re 3.1 Ohms

Voice coil inductance          Le 0.25 mH

Effective piston area          Sd 50.0 cm2

Voice coil diameter                  25.4 mm

Voice coil height                           15 mm

Air gap height                                 5 mm

Linear coil travel                 ( p-p) 10mm

Magnetic Flux Density                  1.03 T

Magnet weight                                 400g

Th/Sm

Moving mass incl. air            Mms 6.1 g

Free air resonance,                Fs 52.5 Hz

Sensitivity (2.83 V / 1 m)            87.0 dB

Mechanical Q-factor                 Qms 5.0

Electrical Q-factor                     Qes 0.33

Total Q-factor                             Qts 0.31

VAS                                                      5.3L

Compliance                  Cms 1.50 mm/N

Force factor                            Bl 4.35 Tm

Rated power handling*                  30 W

Specification Sheet HERE

* IEC 268-5, T/S parameters measured on drive units that are broken in.