Midrange NRX SB-Acoustics 4" SB12MNRX2-25-4 Norex Speaker

Features
Proprietary cone material with natural fibres made in-house
Shortened voice coil optimized for pure midrange reproduction
High damping Butyl rubber surround for non-resonant sound character
Vented pole piece for reduced compression
Vented cast aluminium chassis for optimum strength and low compression
CCAW voice coil for reduced moving mass
Long life silver lead wires
Non-conducting fibre glass coil former for minimum damping
Shorting ring in motor system for reduced distortion

Specs
Nominal Impedance 4 Ω
DC resistance, Re 3.2 Ω
Voice coil inductance, Le 0.15 mH
Effective piston area, Sd 50 cm2
Voice coil diameter 25.4 mm
Voice coil height 9.4 mm
Air gap height 5 mm
Linear coil travel (p-p) 4.4 mm
Magnetic flux density 1.03 T
Magnet weight 0.4 kg
Net weight 0.92 kg
Free air resonance, Fs 63.5 Hz
Sensitivity (2.83V/1m) 90.5 dB
Mechanical Q-factor, Qms 4.19
Electrical Q-factor, Qes 0.35
Total Q-factor, Qts 0.32
Moving mass incl. air,Mms 4.2 g
Force factor, Bl 3.9 Tm
Equivalent volume, Vas 5.3 liters
Compliance, Cms 1.5 mm/N
Mechanical loss, Rms 0.4 kg/s
Rated power handling* 50 W
* IEC 268-5, T/S parameters measured on drive units that are broken in.