Redcatt 21NPWX4 4 ohm 21-inch Woofer speaker

The 21NPW is a high efficiency, (97 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 50mm (2in).

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

General specifications

Nominal Diameter: 21 in.

Rated Impedance: 4 ohm 

Power handling

AES Power: 1800 Watts

Program Power: 3600 Watts

Peak Power: 7200 Watts

Voice Coil

Diameter: 5,3 in

Winding wire: Copper

Former: Glass-Fiber

Winding height: 33 mm

T/S Parameters

Resonant frequency: 34 Hz

Re: 3.0 ohm

Qes: 0,32

Qms: 12

Qts: 0,31

Vas: 168 liters

Sd: 1665 cm2

Sensitivity: 98 db

Mms: 480 grams

Bl: 32

Le: 0.83 mH

Design details

Surround Materia: Fabric

Cone material: Paper with CF

Spider: Triple Nomex

Plate thickness: 12 mm

Peak to peak linear cone Displacement: 15 mm

Overall diameter: 546 mm

Bolt circle diameter: 520 mm

Number of mounting holes: 8

Depth: 250 mm

Net weight: 13,4 Kg

Ordering codes

4 ohm version: 21NPWX4-018

8 ohm version: 21NPWX8-018

16 ohm version: N/A

Recone kits

4 ohm version: RC21NPWX4-018

8 ohm version: RC21NPWX8-018

16 ohm version: N/A