RCF LF21X451

• Sensitivity (1W, 1m, infinite baffle) SPL1W 94.7dB
• Frequency response 28 - 1000Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 28Hz
• Mechanical quality factor QMS 6.90
• Electrical quality factor QES 0.39
• Total quality factor QTS 0.37

Large signal parameters

• Maximum linear excursion xmax 14mm
• Maximum excursion before damage xlim 27mm
• Air volume displaced at xmax VD 2380cm³
• Power handling P 2000W
• Program power Pmax 4000W

Voice Coil

• Nominal impedance Z 8Ω
• DC resistance RE 5.4Ω
• Inductance (1kHz) LE 2.9mH
• VC Diameter 114mm
• Winding height HVC 34mm
• Winding material Copper
• Former material Glass Fiber

Magnet

• Force factor Bl 30.5N/A
• Motor constant Bl/√RE 13.1N/√W
• Air gap height HAG 15mm

Diaphragm

• Effective diameter 470mm
• Effective area SD 1700cm²
• Moving mass MMS 355g
• Moving mass (without air load) MMD 306g

Suspensions

• Stiffness KMS 11.8N/mm
• Compliance CMS 85µm/N
• Equivalent volume to the compliance VAS 385L
• Mechanical resistance RMS 9.05N·s/m
• Spider material with silicon damping

Dimensions

• Nominal diameter 21″
• 533mm
• Overall diameter 547mm
• Baffle cutout diameter 512mm
• Overall depth 245mm
• Volume occupied by the driver 6.5L
• Net weight 15.5kg