• S721400
  • DE 29323089


Elegant designed mid-woofer trimmed for maximum sound quality.
The extremely rigid cone consists of a novel basalt-fiber-paper compound – the perfect combination to guarantee clear and straight sound even at high volume levels. Beside a powerful bass reproduction and peerlessly neutral mids, the S 4B impresses with exceptionally low distortion.

A dream team is the combination with the S 1T tweeter that ideally complements the frequency range. Together with an Audiotec Fischer power amplifier, the S loudspeakers strike up to top form and provide the perfect basis for absolute top sound systems!


  • 4” / 100 mm mid-woofer with novel basalt-fiber-paper compound cone – a perfect combination of lowest weight, high stiffness and inner damping
  • Specially shaped rubber surround for larger effective cone area and increased maximum excursion
  • Individual HELIX basket with additional ventilation holes for better voice coil cooling and high power handling
  • Rugged rubber magnet boot with HELIX-logo
  • Gold-plated terminals

Technical data

Power RMS / max. P 70 / 140 Watts
Impedance  Z 4 Ω
DC resistance  Re 3.4 Ω
Frequency response   75 Hz - 6,000 Hz
Resonance frequency  Fs 120 Hz
Mechanical Q factor  Qms 4.24
Electrical Q factor  Qes 1.11
Total Q factor Qts 0.88
Compliance Cms 232 μm/N
Equivalent air volume Vas 1.2 L
Force factor  B*I 4.1 Tm
Sensitivity 1 W / 1 m SPL 89 dB
Cone area  Sd 61 cm²
Moving mass  Mms 5.9 g
Cone material   Basalt-fiber-paper compound
Mechanical resistance  Rms 1.19 kg/s
Voice coil diameter ø 25 mm
Voice coil winding height   12 mm 
Max. linear excursion  Xmax +/- 3 mm
Outer diameter ø 102 mm / 4.01"
Installation diameter ø 92.3 mm / 3.63"
Installation depth   46.5 mm / 1.83"
Recommended enclosure volumes  
Sealed box  
Net volume   3 L
Lower limiting frequency (-3dB)   100 Hz

Scope of delivery

2 x Mid-woofer HELIX S 4B
1 x Mounting material
1 x Data sheet
1 x Mounting pattern

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