The RCF LF21X451 is a premium 21-inch subwoofer built for ultra-high-output low-frequency performance. Featuring a robust 4.5-inch inside/outside copper voice coil, dual-forced air ventilation, and a fiber-loaded cone, this transducer delivers deep bass, exceptional linearity, and maximum reliability. With 4000W program power handling and high excursion capability, its engineered for demanding professional audio applications requiring both punch and precision.

Product Specifications:

Nominal Diameter: 21″

Rated Impedance: 8 ohm

Program Power: 4000 W

Power Handling (AES): 2000 W

Sensitivity: 97 dB

Frequency Range: 28 Hz 1 kHz

Voice Coil Diameter: 4.5″

Voice Coil Material: Copper

Voice Coil Design: Inside/Outside, 2 layers

Voice Coil Length: 1.34″

Magnet Type: Ceramic

Top Plate Thickness: 0.59″

BL Factor: 30.5 Tm

Inductance (1 kHz): 2.90 mH

Mechanical

Cone: Fiber-loaded, curved design

Surround: Triple-roll polycotton

Spider: Dual with silicon-based damping

Max Excursion (Before Damage): 2.13″

Xmax (Linear Excursion): 0.55″

Thiele-Small Parameters

Resonance Frequency (Fs): 28 Hz

DC Resistance (Re): 5.40 ohm

Qms: 6.90

Qes: 0.39

Qts: 0.37

Moving Mass (Mms): 355 g

Vas: 385 L

Sd: 0.170 m

Efficiency (Half-space): 2.20%

Mounting Information (Inches)

Overall Diameter: 21.54″

Bolt Circle Diameter: 20.75″

Bolt Hole Diameter: 0.28″

Baffle Cut-out (Front/Rear): 20.16″

Driver Depth (Height): 9.65″

Driver Volume Occupied: 0.26 ft

Dimensions & Weight

Height: 9.65″

Diameter: 21.54″

Weight: 34.17 lbs

Package (H x W x D): 11.18″ x 22.99″ x 23.78″

Shipping Weight: 40.79 lbs