Fi Car Audio SP4 18 D1

• Sensitivity (1W, 1m, infinite baffle) SPL1W 88.4dB

Thiele & Small parameters

• Resonance frequency (free air) fS 24.7Hz
• Mechanical quality factor QMS 7.45
• Electrical quality factor QES 0.60
• Total quality factor QTS 0.55

Large signal parameters

• Maximum linear excursion xmax 33mm
• Air volume displaced at xmax VD 3993cm³
• Power handling P 3000W
• Program power Pmax 6000W

Voice Coil

• Nominal impedance Z 2 x 1Ω
• DC resistance (in series) RE 1.3Ω
• Inductance (1kHz, in series, estimated) LE 1.94mH

Magnet

• Force factor (in series) Bl 13.7N/A
• Motor constant Bl/√RE 12N/√W

Diaphragm

• Effective diameter 393mm
• Effective area SD 1210cm²
• Moving mass MMS 555g
• Moving mass (without air load) MMD 525g

Suspensions

• Stiffness KMS 13.5N/mm
• Compliance CMS 74µm/N
• Equivalent volume to the compliance VAS 154L
• Mechanical resistance RMS 11.6N·s/m

Dimensions

• Nominal diameter 18″
• 470mm
• Overall diameter 470mm
• Baffle cutout diameter 425mm
• Mounting depth 286mm
• Volume occupied by the driver 7.36L