Lowther PM4

• Sensitivity (1W, 1m, infinite baffle) SPL1W 98.7dB
• Frequency response 30 - 20000Hz

Thiele & Small parameters

• Resonance frequency (free air) fS 45Hz
• Mechanical quality factor QMS 3.75
• Electrical quality factor QES 0.17
• Total quality factor QTS 0.16

Large signal parameters

• Maximum linear excursion xmax 1mm
• Air volume displaced at xmax VD 21cm³
• Power handling P 100W
• Program power Pmax 200W

Voice Coil

• Nominal impedance Z 8Ω
• DC resistance RE 7.4Ω
• Inductance (1kHz) LE 0.023mH
• VC Diameter 39mm

Magnet

• Flux density B 2.4T
• Force factor Bl 12.5N/A
• Motor constant Bl/√RE 4.6N/√W
• Air gap height HAG 5mm
• Diameter 128mm
• Material Alcomax 3

Diaphragm

• Effective diameter 164mm
• Effective area SD 210cm²
• Moving mass MMS 12.8g
• Moving mass (without air load) MMD 10.4g
• Material Twin Paper

Suspensions

• Stiffness KMS 1.03N/mm
• Compliance CMS 966µm/N
• Equivalent volume to the compliance VAS 60.5L
• Mechanical resistance RMS 0.96N·s/m

Dimensions

• Nominal diameter 8″
• 225mm
• Overall diameter 225mm
• Baffle cutout diameter 190mm
• Overall depth 155mm
• Flange thickness 13mm
• Mounting depth 142mm
• Volume occupied by the driver (estimated) 1.7L