Fountek FM135D-II

• Sensitivity (1W, 1m, infinite baffle) SPL1W 90.4dB
• Frequency response 73 - 5500Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 73Hz
• Mechanical quality factor QMS 1.84
• Electrical quality factor QES 0.33
• Total quality factor QTS 0.28

Large signal parameters

• Maximum linear excursion xmax 1.5mm
• Air volume displaced at xmax VD 12cm³
• Power handling P 30W
• Program power Pmax 60W

Voice Coil

• Nominal impedance Z 8Ω
• DC resistance RE 6.3Ω
• Inductance (1kHz, estimated) LE 0.52mH
• VC Diameter 35.5mm
• Winding height HVC 10mm
• Winding material Copper Clad Aluminium
• Former material Kapton

Magnet

• Flux density B 1T
• Force factor Bl 7.96N/A
• Motor constant Bl/√RE 3.17N/√W
• Air gap height HAG 6mm
• Material Ferrite

Diaphragm

• Effective diameter 103mm
• Effective area SD 83.3cm²
• Moving mass MMS 7.23g
• Moving mass (without air load) MMD 6.7g

Suspensions

• Stiffness KMS 1.52N/mm
• Compliance CMS 656µm/N
• Equivalent volume to the compliance VAS 6.48L
• Mechanical resistance RMS 1.8N·s/m

Dimensions

• Nominal diameter 5.25″
• 135mm
• Overall diameter 132mm
• Overall depth 75mm
• Volume occupied by the driver (estimated) 0.47L
• Net weight 1.85kg