Eminence SIGMA PRO 18-4

• Sensitivity (1W, 1m, infinite baffle) SPL1W 97.1dB
• Frequency response 32 - 2000Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 32Hz
• Mechanical quality factor QMS 14.79
• Electrical quality factor QES 0.30
• Total quality factor QTS 0.29

Large signal parameters

• Maximum linear excursion xmax 7mm
• Maximum excursion before damage xlim 18mm
• Air volume displaced at xmax VD 798cm³
• Power handling P 700W
• Program power Pmax 1400W

Voice Coil

• Nominal impedance Z 4Ω
• DC resistance RE 3.4Ω
• Inductance (1kHz) LE 0.85mH
• VC Diameter 76mm
• Winding material Copper
• Former material Polyimide

Magnet

• Force factor Bl 16.5N/A
• Motor constant Bl/√RE 9.04N/√W
• Air gap height HAG 9.5mm
• Weight 3.402kg
• Material Ferrite

Diaphragm

• Effective diameter 381mm
• Effective area SD 1140cm²
• Moving mass MMS 121g
• Moving mass (without air load) MMD 93.7g
• Material Paper

Suspensions

• Stiffness KMS 5N/mm
• Compliance CMS 200µm/N
• Equivalent volume to the compliance VAS 361L
• Mechanical resistance RMS 1.64N·s/m
• Surround material Cloth

Dimensions

• Nominal diameter 18″
• 457mm
• Overall diameter 457mm
• Baffle cutout diameter 421mm
• Overall depth 207mm
• Volume occupied by the driver 6.62L
• Net weight 11.11kg
• Frame material Die-cast aluminum