Eighteen Sound 18NLS4000

• Sensitivity (1W, 1m, infinite baffle) SPL1W 91.4dB
• Frequency response 28 - 500Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 27Hz
• Mechanical quality factor QMS 13.70
• Electrical quality factor QES 0.36
• Total quality factor QTS 0.35

Large signal parameters

• Maximum linear excursion xmax 22.3mm
• Air volume displaced at xmax VD 2732cm³
• Power handling P 1200W
• Program power Pmax 2400W

Voice Coil

• Nominal impedance Z 4Ω
• DC resistance RE 2.9Ω
• Inductance (1kHz) LE 2.6mH
• VC Diameter 100mm
• Winding height HVC 52mm

Magnet

• Force factor Bl 24.2N/A
• Motor constant Bl/√RE 14.2N/√W
• Air gap height HAG 15mm

Diaphragm

• Effective diameter 395mm
• Effective area SD 1225cm²
• Moving mass MMS 433g
• Moving mass (without air load) MMD 403g

Suspensions

• Stiffness KMS 12.5N/mm
• Compliance CMS 80µm/N
• Equivalent volume to the compliance VAS 168L
• Mechanical resistance RMS 5.36N·s/m

Dimensions

• Nominal diameter 18″
• 462mm
• Overall diameter 462mm
• Baffle cutout diameter 422mm
• Overall depth 250mm
• Flange thickness 24mm
• Mounting depth 226mm
• Volume occupied by the driver (estimated) 7.6L
• Net weight 12.0kg