Dayton Audio Ultimax UM18-22

• Sensitivity (1W, 1m, infinite baffle) SPL1W 86.8dB
• Frequency response 19 - 500Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 26.2Hz
• Mechanical quality factor QMS 4.05
• Electrical quality factor QES 0.85
• Total quality factor QTS 0.70

Large signal parameters

• Maximum linear excursion xmax 22mm
• Air volume displaced at xmax VD 2682cm³
• Power handling P 1000W
• Program power Pmax 2000W

Voice Coil

• Nominal impedance Z 2 x 2Ω
• DC resistance (in series) RE 4.3Ω
• Inductance (1kHz, in series) LE 1.5mH
• VC Diameter 75mm

Magnet

• Force factor (in series) Bl 21.1N/A
• Motor constant Bl/√RE 10.2N/√W
• Material Ferrite

Diaphragm

• Effective diameter 394mm
• Effective area SD 1219cm²
• Moving mass MMS 532g
• Moving mass (without air load) MMD 502g
• Material Nomex

Suspensions

• Stiffness KMS 14.3N/mm
• Compliance CMS 70µm/N
• Equivalent volume to the compliance VAS 145L
• Mechanical resistance RMS 21.6N·s/m
• Surround material Rubber

Dimensions

• Nominal diameter 18″
• 462mm
• Overall diameter 462mm
• Baffle cutout diameter 426mm
• Overall depth 248mm
• Volume occupied by the driver (estimated) 8.5L
• Frame material Cast Aluminium