Skar Audio SDR-18 D4

• Sensitivity (1W, 1m, infinite baffle) SPL1W 88.6dB

Thiele & Small parameters

• Resonance frequency (free air) fS 24Hz
• Mechanical quality factor QMS 4.99
• Electrical quality factor QES 0.59
• Total quality factor QTS 0.76

Large signal parameters

• Maximum linear excursion xmax 13.5mm
• Air volume displaced at xmax VD 1572cm³
• Power handling P 600W
• Program power Pmax 1200W

Voice Coil

• Nominal impedance Z 2 x 4Ω
• DC resistance (in series) RE 1.0Ω
• Inductance (1kHz, in series, estimated) LE 1.25mH
• VC Diameter 63.5mm
• Winding material Copper

Magnet

• Force factor (in series) Bl 10.7N/A
• Motor constant Bl/√RE 10.7N/√W
• Diameter 155mm

Diaphragm

• Effective diameter 385mm
• Effective area SD 1164cm²
• Moving mass MMS 429g
• Moving mass (without air load) MMD 401g
• Material Pressed Paper

Suspensions

• Stiffness KMS 9.62N/mm
• Compliance CMS 104µm/N
• Equivalent volume to the compliance VAS 200L
• Mechanical resistance RMS 13N·s/m
• Surround material Foam

Dimensions

• Nominal diameter 18″
• 465mm
• Overall diameter 465mm
• Baffle cutout diameter 420mm
• Overall depth 231mm
• Flange thickness 29mm
• Mounting depth 202mm
• Volume occupied by the driver (estimated) 7.8L