RCF LF21N551

• Sensitivity (1W, 1m, infinite baffle) SPL1W 95.3dB
• Frequency response 30 - 1000Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 35Hz
• Mechanical quality factor QMS 6.20
• Electrical quality factor QES 0.35
• Total quality factor QTS 0.33

Large signal parameters

• Maximum linear excursion xmax 15mm
• Maximum excursion before damage xlim 36mm
• Air volume displaced at xmax VD 2550cm³
• Power handling P 2000W
• Program power Pmax 4000W

Voice Coil

• Nominal impedance Z 8Ω
• DC resistance RE 5.2Ω
• Inductance (1kHz) LE 3.2mH
• VC Diameter 135mm
• Winding height HVC 39mm
• Winding material Copper

Magnet

• Force factor Bl 39N/A
• Motor constant Bl/√RE 17.1N/√W
• Material Neodymium

Diaphragm

• Effective diameter 470mm
• Effective area SD 1700cm²
• Moving mass MMS 434g
• Moving mass (without air load) MMD 385g

Suspensions

• Stiffness KMS 20.4N/mm
• Compliance CMS 49µm/N
• Equivalent volume to the compliance VAS 200L
• Mechanical resistance RMS 15.4N·s/m
• Surround material Polycotton

Dimensions

• Nominal diameter 21″
• 533mm
• Overall diameter 547mm
• Baffle cutout diameter 512mm
• Overall depth 260mm
• Flange thickness 18mm
• Mounting depth 242mm
• Volume occupied by the driver 7.2L
• Net weight 14.0kg