Beyma 4FR40Nd

• Sensitivity (1W, 1m, infinite baffle) SPL1W 86.4dB
• Frequency response 100 - 20000Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 94Hz
• Mechanical quality factor QMS 10.80
• Electrical quality factor QES 0.78
• Total quality factor QTS 0.73

Large signal parameters

• Maximum linear excursion xmax 3mm
• Air volume displaced at xmax VD 17cm³
• Power handling P 40W
• Program power Pmax 80W

Voice Coil

• Nominal impedance Z 8Ω
• DC resistance RE 6.4Ω
• Inductance (1kHz) LE 0.2mH
• VC Diameter 20.3mm
• Winding height HVC 7.7mm

Magnet

• Force factor Bl 4.7N/A
• Motor constant Bl/√RE 1.86N/√W
• Air gap height HAG 4mm
• Material Neodymium

Diaphragm

• Effective diameter 84mm
• Effective area SD 55cm²
• Moving mass MMS 4.5g
• Moving mass (without air load) MMD 4.2g

Suspensions

• Stiffness KMS 1.6N/mm
• Compliance CMS 627µm/N
• Equivalent volume to the compliance VAS 2.7L
• Mechanical resistance RMS 0.25N·s/m

Dimensions

• Nominal diameter 4″
• 100mm
• Volume occupied by the driver (estimated) 0.1L
• Net weight 0.28kg