Eighteen Sound 21NTLW5000 8Ω

• Sensitivity (1W, 1m, infinite baffle) SPL1W 94.7dB
• Frequency response 30 - 1800Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 31Hz
• Mechanical quality factor QMS 5.20
• Electrical quality factor QES 0.38
• Total quality factor QTS 0.36

Large signal parameters

• Maximum linear excursion xmax 17.5mm
• Air volume displaced at xmax VD 2909cm³
• Power handling P 1800W
• Program power Pmax 4000W

Voice Coil

• Nominal impedance Z 8Ω
• DC resistance RE 5.3Ω
• Inductance (1kHz) LE 1.6mH
• VC Diameter 115mm
• Winding height HVC 42.5mm

Magnet

• Force factor Bl 32N/A
• Motor constant Bl/√RE 13.9N/√W
• Air gap height HAG 15mm
• Material Neodymium

Diaphragm

• Effective diameter 460mm
• Effective area SD 1662cm²
• Moving mass MMS 372g
• Moving mass (without air load) MMD 325g

Suspensions

• Stiffness KMS 14.1N/mm
• Compliance CMS 71µm/N
• Equivalent volume to the compliance VAS 270L
• Mechanical resistance RMS 13.9N·s/m

Dimensions

• Nominal diameter 21″
• 533mm
• Overall diameter 545mm
• Baffle cutout diameter 492mm
• Overall depth 320mm
• Flange thickness 18mm
• Mounting depth 302mm
• Volume occupied by the driver (estimated) 10L
• Net weight 12.5kg