Media
Auto-advancing
Size
21"
Impedance
4Ω
RMS Power
4000W
Sensitivity
96dB
EBP
103
Vented alignment
Vd
2520cm³
Frequency response
Manufacturer-provided response plots and related charts.
T/S Parameters
Valid
Fs32Hz
Qts0.30
Qes0.31
Qms7.0
Vas200.0L
Re3.3Ω
Le1.50mH
BL32.5Tm
Sd1680cm²
Mms460g
Xmax15.0mm
SPL96dB
Power4000W
Power Nominal2000W
Impedance4Ω
Min Impedance4.2Ω
F Low30Hz
F High1000Hz
Voice Coil153mm
Flux Density1.20T
Pricing & availability
Price movement
Other offers
1 vendorjpleisure
Updated 17 May 2026· 4Ω
Source: ex VAT · 20%
£656.00
inc VAT
Best current price
Updated 17 May 2026
bluearan
£499.00
Avg £577.50£78.50 below avg (-13.6%)
inc VAT
Dimensions & Physical
Weight18.5kg
Diameter547.0mm
Overall Depth261.0mm
Cutout Diameter508.0mm
Bolt Circle Diameter527.0mm
Additional Manufacturer Specs
Bl32.5 Tm
Fs32 Hz
Le1.5 mH
Re3.3 Ω
Sd1680 cm² (260.4 in²)
Ebp103 Hz
Mms460 g
Qes0.31
Qms7
Qts0.3
Vas200 dm³ (7 ft³)
η02.2 %
ConeRCK21SW1524
Xmax15 mm
Xvar16 mm
SpiderDouble Silicone
Cone ShapeRadial
Pole DesignT-Pole
Winding Depth30 mm (1.18 in)
Surround ShapeTriple Roll
Former MaterialGlass Fibre
Magnet MaterialNeodymium Inside Slug
Nominal Diameter530 mm (21 in)
Winding MaterialCopper
Magnetic Gap Depth12 mm (0.5 in)
Recommended Tuning33 Hz
Bolt Circle Diameter527 mm (20.7 in)
Recommended Enclosure190 dm³ (6.71 ft³)
Woofer Cone TreatmentTWP Waterproof Both Sides
Baffle Cutout Diameter508 mm (20 in)
Flange And Gasket Thickness16 mm (0.63 in)
Air Volume Occupied By Driver16 dm³ (0.56 ft³)
Similar Drivers
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Reference
B&C
21SW152
21"
Best current price
£499.00
Compare on
Only active params are shown here. Size stays fixed automatically.
5 active T/S params, plus size.
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