4″ SB12MNRX2-25-4 / Norex


  • 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
Categories: ,

Additional information

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


(2.83 V / 1 m) 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


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.



There are no reviews yet.

Be the first to review “4″ SB12MNRX2-25-4 / Norex”

Your email address will not be published. Required fields are marked *