Features

A special reinforced model for car audio application.
The new 21SW4000-NDY-2 is an advanced, high-strength Neodymium subwoofer driver featuring a 5.3” inside/outside copper coil with an unique dual forced design ventilation system. This combination deliveries 2000 Watts RMS power handling and a minimum weight of 30.2 lbs. making this subwoofer an unique product in his category.
The combination of special treated carbon fiber loaded cone assembly, large triple roll surround and a double silicon spider gives the 21SW4000-NDY-2 remarkable strength and excursion control under its large 15 mm Xmax, 72 mm peak-to-peak excursion before damage.
Featuring a 2 ohms voice coil and unmatchable low frequency output with a fully optimized T-pole design, this 21” subwoofer creates a whole new category on its class!
Highlights
- Nominal Impedance: 2 Ohms
- Rated AES Power Handling (RMS): 2000 Watts
- Program Power: 4000 Watts
- Sensitivity (1W/1m): 97 dB
- Voice Coil Diameter: 5.3″
Technical Details
GENERAL SPECIFICATIONS
Nominal Diameter | 21″ (553 mm) |
Nominal impedance | 2 Ohms |
Rated AES Power Handling (RMS) | 2000 Watts |
Program Power | 4000 Watts |
Sensitivity 1.41V at 1m | 97 dB |
Recommended Hi Pass Crossover** **For Full Power Handling |
45 Hz** **12db Per Octave Crossover |
Frequency Response at -10dB | 35 – 1,200 Hz |
Voice Coil Diameter | 5.3″ (135 mm) |
Voice Coil Wire | Copper |
Voice Coil Winding Depth | 39.0 mm |
Former Material | Glass Fiber |
Magnetic Gap Depth | 18.0 mm |
Frame Material | Die Cast Aluminum |

THIELE-SMALL PARAMETERS
Equivalent Volume | Vas | 284.7 l |
Excursion (mathematical)*** | Xmax | 15.00 mm |
Free Air Resonance | Fs | 30.8 Hz |
Mechanical Factor | Qms | 12.33 |
Electrical Factor | Qes | 0.28 |
Total Factor | Qts | 0.28 |
Cone Area | Sd | 1924 cm² |
Mechanical Mass | Mms | 485.0 g |
Bl Factor | Bl | 24.36 Tm |
Dc Resistance | Re | 1.8 Ohms |
Inductance | Le | 1.14 mH at 1 kHz |
Mechanical Mass Without Air | Mmd | 437.2 g |
Mechanical Compliance | Cms | 0.055 mm/N |
***Xmax=(Voice coil winding depth-Magnetic Gap depth)/2+ Mgnetic Gap Depth/4

EXTRA INFO
Overall Diameter | 21.53” (547 mm) |
Front Mount Baffle Cutout | 20.0” (508 mm) |
Mounting Depth | 9.64” (245 mm) |
Overall Depth | 10.23” (265 mm) |
Net Weight | 30.2 Lbs (13.7 kg) |
Shipping Weight | 35.3 Lbs (16.0 kg) |
Carton Dimensions W x L x H | 23.2” x 22.4” x 10.8” (590 x 570 x 275 mm) |
