LF
Sub-woofer
21"
21NPW
Code: DR-21-002-4R-B2-C0001
Sub-Woofer/21inch/Neo/Paper/1800W/4ohm
Key Features
- 5.3” diameter voice coil
- 3600 watts program power handling
- Triple silicone spider, heavy duty fiber reinforced cone with large surround
Quick Specs
Impedance
4 Ω
Program Power
3600 W
Sensitivity
96.32 dB
Fs
35.00 Hz
Magnet
Neodymium
Voice Coil
134.6 mm
Design Notes
The 21NPW is a high efficiency, (96 dB 1watt / 1 meter) 21-inch woofer with incredibly linear frequency response characteristics, extreme high power handling capability while generating low harmonic distortion artifacts. The 21NPW uses a lightweight carbon fiber loaded cone assembly along with a high excursion triple roll constant geometry surround. This combination provides remarkable strength, high efficiency and a peak to peak maximum excursion of 31mm.
Power Handling
At the core of the 21NPW is it’s voice coil technology featuring a composite Polyimide former material capable of withstanding peak temperatures in excess of 350C, well beyond the thermal requirements of modern professional audio systems. The 21NPW delivers incredible performance.
REDCATT has implemented a triple layer/silicone spider design to ensure long term Fs memory, consistency and diminish anomalies associated with spider deterioration.
Power Handling
At the core of the 21NPW is it’s voice coil technology featuring a composite Polyimide former material capable of withstanding peak temperatures in excess of 350C, well beyond the thermal requirements of modern professional audio systems. The 21NPW delivers incredible performance.
REDCATT has implemented a triple layer/silicone spider design to ensure long term Fs memory, consistency and diminish anomalies associated with spider deterioration.
Specifications
General Specs
Nominal Diameter
21"
Rated Impedance
4 Ohm
Magnet
Neodymium
Basket Material
Aluminum
Power Handling
AES Power
1800 W
Continuous Power
3600 W
Peak Power
7200 W
Voice Coil
Diameter
134.6 mm
Winding Wire
Copper
Former
Glass Fiber
Winding Height
33 mm
T/S Parameters
Resonant Frequency (Fs)
35.00 Hz
Re
3.00 \u2126
Qes
0.330
Qms
11.12
Qts
0.320
Vas
149.00 liters
Sd
1662.00 cm\u00B2
Mms
514.00 grams
Rms
10.16
Cms
0.0400
Bl
32.90 T\u00B7m
Le
1.140 mH
Sensitivity
96.32 dB
Design Details
Surround Material
fabric
Cone/Dome Material
Paper CF
Spider
Nomex
T-Plate
15 mm
Xmax (peak)
9 mm
Xmech
24 mm
Overall Diameter
546.00 mm
Bolt Circle Diameter
520.00 mm
Baffle Cutout Dia.
496.00 mm
Mounting Holes
8
Depth (flange to rear)
245.00 mm
Net Weight
14.85 kg
Ordering Codes
Product Code
DR-21-002-4R-B2-C0001
Downloads
Frequency Response & Impedance
2D Drawing
Technical Summary
The 21NPWX4-018 is a 21-inch professional sub-woofer driver rated at 1800 W AES (3600 W continuous) into a nominal 4-ohm impedance, designed for touring, large-venue installation, and high-SPL bass reinforcement systems requiring maximum output in the sub-bass frequency range. The driver delivers 96.32 dB sensitivity (1W/1m), among the highest in its class for a 21-inch frame, and is built around a neodymium motor generating a Bl of 32.9 T.m - providing exceptionally tight cone control at high drive levels with reduced thermal compression over sustained operation.
The driver is rated for use with amplification of approx. 1800 W AES (3600 W continuous) into 4 ohms, with a high-pass filter recommended in the 24-35 Hz range depending on alignment. DSP processing with excursion limiting is essential at sustained high-power levels; below the tuning frequency, cone excursion increases rapidly and approaches the 9 mm Xmax before thermal limits are reached. Two drivers wired in parallel present a 2-ohm load; series wiring presents 8 ohms.
The 21NPWX4-018 is intended for professional touring sub arrays, stadium and large-venue ground stacks, club and nightclub subwoofer installations, concert infrastructure subwoofer systems, and fixed-install bass reinforcement in venues where the combination of high sensitivity, extreme power handling (Polyimide former rated to 350 degC), and maximum cone displacement define the required performance envelope.
The driver is rated for use with amplification of approx. 1800 W AES (3600 W continuous) into 4 ohms, with a high-pass filter recommended in the 24-35 Hz range depending on alignment. DSP processing with excursion limiting is essential at sustained high-power levels; below the tuning frequency, cone excursion increases rapidly and approaches the 9 mm Xmax before thermal limits are reached. Two drivers wired in parallel present a 2-ohm load; series wiring presents 8 ohms.
The 21NPWX4-018 is intended for professional touring sub arrays, stadium and large-venue ground stacks, club and nightclub subwoofer installations, concert infrastructure subwoofer systems, and fixed-install bass reinforcement in venues where the combination of high sensitivity, extreme power handling (Polyimide former rated to 350 degC), and maximum cone displacement define the required performance envelope.
Recommended enclosure volumes are simulated results. For best enclosure volumes and tuning, we recommend secondary simulation and careful evaluation. Several rounds of samples and fine-tuning may be required for optimal results.
Enclosure Recommendations
Recommended enclosure alignments (bass reflex): - 125 liters tuned to 38 Hz: high output, strong mid-bass, reduced excursion; -3 dB approx. 35 Hz, HP filter 30 Hz - 150 liters tuned to 34 Hz: balanced response, general-purpose (recommended); -3 dB approx. 29 Hz, HP filter 24 Hz - 175 liters tuned to 29 Hz: extended low-frequency, requires HP filter protection; -3 dB approx. 25 Hz, HP filter 20 Hz
Frequently Asked Questions
- - 5.3” diameter voice coil
- - 3600 watts program power handling
- - Triple silicone spider, heavy duty fiber reinforced cone with large surround
Recommended enclosure alignments (bass reflex): - 125 liters tuned to 38 Hz: high output, strong mid-bass, reduced excursion; -3 dB approx. 35 Hz, HP filter 30 Hz - 150 liters tuned to 34 Hz: balanced response, general-purpose (recommended); -3 dB approx. 29 Hz, HP filter 24 Hz - 175 liters tuned to 29 Hz: extended low-frequency, requires HP filter protection; -3 dB approx. 25 Hz, HP filter 20 Hz
Outdoor / weather-resistant; large-format vented or horn-loaded subwoofer / infra-bass; weight-critical installs
AES Power: 1800 W,
Continuous: 3600 W,
Peak: 7200 W.
Sensitivity: 96.32 dB (1W/1m).
