Eighteen Sound 21NLW4100 8Ω

• Sensitivity (1W, 1m, infinite baffle) SPL1W 94.2dB
• Frequency response 32 - 300Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 36Hz
• Mechanical quality factor QMS 7.80
• Electrical quality factor QES 0.49
• Total quality factor QTS 0.46

Large signal parameters

• Maximum linear excursion xmax 15.2mm
• Air volume displaced at xmax VD 2525cm³
• Power handling P 1500W
• Program power Pmax 3000W

Voice Coil

• Nominal impedance Z 8Ω
• DC resistance RE 5.1Ω
• Inductance (1kHz) LE 2.1mH
• VC Diameter 100mm
• Winding height HVC 36.5mm
• Winding material Copper

Magnet

• Force factor Bl 29.4N/A
• Motor constant Bl/√RE 13N/√W
• Air gap height HAG 12.4mm
• Material Neodymium

Diaphragm

• Effective diameter 460mm
• Effective area SD 1661cm²
• Moving mass MMS 374g
• Moving mass (without air load) MMD 327g
• Material Water repellent

Suspensions

• Stiffness KMS 19.2N/mm
• Compliance CMS 52µm/N
• Equivalent volume to the compliance VAS 210L
• Mechanical resistance RMS 10.9N·s/m

Dimensions

• Nominal diameter 21″
• 533mm
• Overall diameter 545mm
• Baffle cutout diameter 492mm
• Overall depth 247mm
• Flange thickness 7mm
• Mounting depth 240mm
• Volume occupied by the driver (estimated) 7.7L
• Net weight 10.5kg