Fi Car Audio SP3 18 D1

• Sensitivity (1W, 1m, infinite baffle) SPL1W 91.8dB

Thiele & Small parameters

• Resonance frequency (free air) fS 32.1Hz
• Mechanical quality factor QMS 7.41
• Electrical quality factor QES 0.43
• Total quality factor QTS 0.41

Large signal parameters

• Maximum linear excursion xmax 34mm
• Air volume displaced at xmax VD 4114cm³
• Power handling P 2500W
• Program power Pmax 5000W

Voice Coil

• Nominal impedance Z 2 x 1Ω
• DC resistance (in series) RE 1.8Ω
• Inductance (1kHz, in series, estimated) LE 2.13mH

Magnet

• Force factor (in series) Bl 18.2N/A
• Motor constant Bl/√RE 13.6N/√W

Diaphragm

• Effective diameter 393mm
• Effective area SD 1210cm²
• Moving mass MMS 394g
• Moving mass (without air load) MMD 364g

Suspensions

• Stiffness KMS 16N/mm
• Compliance CMS 62.5µm/N
• Equivalent volume to the compliance VAS 128L
• Mechanical resistance RMS 10.7N·s/m

Dimensions

• Nominal diameter 18″
• 470mm
• Overall diameter 470mm
• Baffle cutout diameter 425mm
• Mounting depth 311mm
• Volume occupied by the driver 7.36L