Media
Auto-advancing
Size
21"
Impedance
4Ω
RMS Power
3400W
Sensitivity
97dB
EBP
89
Either alignment
Vd
2352cm³
Frequency response
Manufacturer-provided response plots and related charts.
T/S Parameters
Valid
Fs33Hz
Qts0.36
Qes0.37
Qms7.7
Vas278.0L
Re3.6Ω
Le1.70mH
BL24.8Tm
Sd1680cm²
Mms335g
Xmax14.0mm
SPL97dB
Power3400W
Power Nominal1700W
Impedance4Ω
Min Impedance4.2Ω
F Low33Hz
F High1000Hz
Voice Coil116mm
Flux Density1.15T
Pricing & availability
Price movement
Other offers
1 vendorjpleisure
Updated 17 May 2026· 4Ω
Source: ex VAT · 20%
£499.52
inc VAT
Best current price
Updated 17 May 2026
bluearan
£435.00
Avg £467.26£32.26 below avg (-6.9%)
inc VAT
Dimensions & Physical
Weight14.0kg
Diameter547.0mm
Overall Depth249.0mm
Cutout Diameter503.0mm
Bolt Circle Diameter527.0mm
Additional Manufacturer Specs
Bl24.8 Tm
Fs33 Hz
Le1.7 mH
Re3.6 Ω
Sd1680 cm² (260.4 in²)
Ebp89 Hz
Mms335 g
Qes0.37
Qms7.7
Qts0.36
Vas278 dm³ (9.7 ft³)
η02.6 %
ConeRCK21SW1154
Xmax14 mm
Xvar15 mm
SpiderDouble Silicone
Cone ShapeRadial
Pole DesignT-Pole
Winding Depth34 mm (1.34 in)
Surround ShapeTriple Roll
Former MaterialGlass Fibre
Magnet MaterialNeodymium Inside Slug
Nominal Diameter530 mm (21 in)
Winding MaterialCopper
Magnetic Gap Depth14 mm (0.55 in)
Recommended Tuning32 Hz
Bolt Circle Diameter527 mm (20.7 in)
Recommended Enclosure250 dm³ (8.83 ft³)
Woofer Cone TreatmentTWP Waterproof Both Sides
Baffle Cutout Diameter503 mm (19.8 in)
Flange And Gasket Thickness14 mm (0.53 in)
Air Volume Occupied By Driver15 dm³ (0.53 ft³)
Similar Drivers
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Reference
B&C
21SW115
21"
Best current price
£435.00
Compare on
Only active params are shown here. Size stays fixed automatically.
5 active T/S params, plus size.
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