Eighteen Sound 8NMB420

• Sensitivity (1W, 1m, infinite baffle) SPL1W 94.1dB
• Frequency response 60 - 5500Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 59Hz
• Mechanical quality factor QMS 3.81
• Electrical quality factor QES 0.34
• Total quality factor QTS 0.31

Large signal parameters

• Maximum linear excursion xmax 5.8mm
• Air volume displaced at xmax VD 132cm³
• Power handling P 280W
• Program power Pmax 400W

Voice Coil

• Nominal impedance Z 4Ω
• DC resistance RE 2.6Ω
• Inductance (1kHz) LE 0.27mH
• VC Diameter 51mm

Magnet

• Force factor Bl 7N/A
• Motor constant Bl/√RE 4.34N/√W

Diaphragm

• Effective diameter 170mm
• Effective area SD 227cm²
• Moving mass MMS 16.9g
• Moving mass (without air load) MMD 14.4g
• Material Weather protected

Suspensions

• Stiffness KMS 2.32N/mm
• Compliance CMS 431µm/N
• Equivalent volume to the compliance VAS 31L
• Mechanical resistance RMS 1.64N·s/m

Dimensions

• Nominal diameter 8″
• 200mm
• Overall diameter 210mm
• Baffle cutout diameter 186mm
• Overall depth 99mm
• Flange thickness 14mm
• Mounting depth 85mm
• Volume occupied by the driver (estimated) 0.72L
• Net weight 1.7kg