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18Sound

SPEAKER 18SOUND 21" 21ID 2OHMS

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SKU:
53604
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Description

The 21iD is an 21 inch neodymium high performance subwoofer. The loudspeaker has been optimized for vented and bandpass subwoofer cabinet designs and is recommended to use a Class D or iPal (tm*) amplifier able to deliver 3600 Watt program power without clipping. Eighteen Sound engineers have obtained the best possible results with today's available materials in terms of clean and undistorted LF reproduction at a ultra high SPL, with the lowest possible power compression figure. The transducer design features include a large displacement suspension system specifically designed for matching the composite fiber reinforced, straight ribbed cone. Thanks to the Triple Silicon Spider (TSS) technology, the 21iD is able to control the moving mass with high linearity, showing an exceptional stability of mechanical parameter values in the long term. Bl force factor, as well as all other electro-dynamic parameters, are linear within the working range. This, together with the exceptional high excursion behavior - 70mm before damage, ±14mm linear Xmax - makes the 21iD an extremely low distortion, highly dynamic transducer. The 21iD features a state-of-the-art 5,3" inside outside copper ISV (Interleaved Sandwich Voice-Coil) enabling the 21iD to deliver extraordinary transient results. The 21iD has been developed after intense FEA and fluidodynamics simulation and testing,focusing on dissipating the heat generated by the powerful voice coil. Special attention was given to the optimization of air flow into the gap without introducing audible noise. A low-density material air diffractor placed into the heatsink acts as a cooling system, increasing the power handling capability and lowering the power compression figure.

FS
38 Hz
QTS
0.23
VAS
143 L
SD
1660 cm²
XMAX
± 14 mm
Resonant frequency fS 38 Hz
Electrical Q QES 0.24
Mechanical Q QMS 5.60
Total Q factor QTS 0.23
Suspension equivalent air volume VAS 143 litres
DC resistance RE 1.3 Ω
Minimum impedance Zmin 2.0 Ω
Voice coil inductance LE 1.08 mH
Force factor B·l 25.2 T·m
Suspension mechanical resistance RMS 20.8 N·s/m
Suspension mechanical compliance CMS 37 µm/N
Moving mass MMD 441.5 g
Moving mass (including airload) MMS 489 g
Surface of the diaphragm SD 1660 cm²
Effective diaphragm diameter Ø 46 cm
Maximum linear excursion Xmax ± 14 mm
Excursion limit Xlim ± 35 mm
Displacement volume at Xmax VD 2324 cm³
Efficiency η₀ 3.19 %
Efficiency bandwidth product EBP 158
Overall diameter 545 mm
Baffle hole diameter 490 mm
Overall depth 250 mm
Flange thickness 18 mm
Net weight 13.6 kg
Diaphragm material Straight ribbed carbon fiber loaded cellulose
Surround material Triple Roll, Polycotton
Voice coil diameter 135 mm
Coil material Copper
Magnet Neodymium
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