Dayton Audio Ultimax II UMII18-22

• Sensitivity (1W, 1m, infinite baffle) SPL1W 87.5dB
• Frequency response 20 - 500Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 22Hz
• Mechanical quality factor QMS 2.53
• Electrical quality factor QES 0.67
• Total quality factor QTS 0.53

Large signal parameters

• Maximum linear excursion xmax 28mm
• Air volume displaced at xmax VD 3315cm³
• Power handling P 1200W
• Program power Pmax 2400W

Voice Coil

• Nominal impedance Z 2 x 2Ω
• DC resistance (in series) RE 4.2Ω
• Inductance (1kHz, in series) LE 1.15mH
• VC Diameter 76mm

Magnet

• Force factor (in series) Bl 19.2N/A
• Motor constant Bl/√RE 9.37N/√W
• Material Ferrite

Diaphragm

• Effective diameter 388mm
• Effective area SD 1184cm²
• Moving mass MMS 420g
• Moving mass (without air load) MMD 393g
• Material Carbon Fiber

Suspensions

• Stiffness KMS 8.07N/mm
• Compliance CMS 124µm/N
• Equivalent volume to the compliance VAS 248L
• Mechanical resistance RMS 23N·s/m
• Surround material Rubber

Dimensions

• Nominal diameter 18″
• 427mm
• Overall diameter 427mm
• Baffle cutout diameter 220mm
• Overall depth 229mm
• Volume occupied by the driver (estimated) 6.9L
• Frame material Cast Aluminium