Fostex FE108EΣ

• Sensitivity (1W, 1m, infinite baffle) SPL1W 91.7dB
• Frequency response 77 - 23000Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 77Hz
• Mechanical quality factor QMS 7.79
• Electrical quality factor QES 0.32
• Total quality factor QTS 0.30

Large signal parameters

• Maximum linear excursion xmax 0.3mm
• Air volume displaced at xmax VD 1.4cm³
• Power handling P 8W
• Program power Pmax 24W

Voice Coil

• Nominal impedance Z 8Ω
• DC resistance RE 6.8Ω
• Inductance (1kHz) LE 0.038mH
• VC Diameter 20mm

Magnet

• Force factor Bl 5.2N/A
• Motor constant Bl/√RE 1.99N/√W
• Weight 0.4kg
• Material Ferrite

Diaphragm

• Effective diameter 80mm
• Effective area SD 50cm²
• Moving mass MMS 2.7g
• Moving mass (without air load) MMD 2.4g

Suspensions

• Stiffness KMS 0.629N/mm
• Compliance CMS 1590µm/N
• Equivalent volume to the compliance VAS 5.7L
• Mechanical resistance RMS 0.17N·s/m

Dimensions

• Nominal diameter 4″
• 100mm
• Overall diameter 128mm
• Baffle cutout diameter 100mm
• Overall depth 65mm
• Volume occupied by the driver (estimated) 0.32L
• Net weight 1.2kg