SB21SDC-C000-4 / Fabric


  • Large surround dome for increased acoustic output.
  • Dual balanced compression chamber for improved dynamics.
  • Copper cap for reduced voice coil inductance and minimum phase shift.
  • Saturation controlled motor system for low distortion.
  • Non-reflective rear chamber with optimized dampingfor improved dynamics.
  • Flow optimized vented pole piece for optimum
    coupling to rear chamber.
  • CCAW voice coil for low moving mass.
  • Long life silver lead wires.
  • Low resonance frequency.
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Additional information

Nominal Impedance

4 Ω

DC resistance

Re 3.1 Ω

Voice coil inductance

Le 0.04 mH

Effective piston area

Sd 4.9 cm2

Voice coil diameter

20.4 mm

Voice coil height

1.5 mm

Air gap height

2.5 mm

Linear coil travel (p-p)

1.0 mm

Moving mass incl. air

Mms 0.25 g

Free air resonance

Fs 720 Hz


(2.83V/1m) 91 dB

Mechanical Q-factor

Qms 2.41

Electrical Q-factor

Qes 1.55

Total Q-factor

Qts 0.95

Force factor

Bl 1.5 Tm

Rated power handling

*40 W

Magnetic flux density

1.02 T

Magnet weight

0.13 kg

Net Weight

0.33 kg


*IEC 268-5, high-pass Butterworth, 2600 Hz, 12 dB/oct

SB21SDC-C000-4 Datasheet