Fostex FF 85 WK - Fullrange

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-6 %

RRP 73,60 €

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-6 %

ø70mm large ferrite magnet
Special paper cone made of non-wood pulp fiber [KENAF] and bio-cellulose fiber
UDR tangential edge
Aluminum center radiator connected onto voice coil

Key features:
  • A double-­layer cone paper consists of two layers. One is a basic layer and the other is a surface layer. In the FF-­WK series, a long-­fibered (low freeness) wooden pulp is used for the basic layer, which has high rigidity realized by the large volume structure and appropriate internal loss. For the surface layer, the bincho charcoal powder is blended with a short-­fibered (high freeness) kenaf, which allows to accelerate the propagation speed on the cone paper surface.The up-­roll edge shape realizes a long stroke. A polycarbonate series material which has opposite physicalities of high loss and high Young’s modulus is specially blended with urethane foam.
  • A ridge-­dome shape center cap made of aluminum alloy is employed. Dispersing and deadening a resonance occurred at a specific frequency with this cap helps to ease an unnecessary sound coloration at high frequency range. Also direct coupling with the voice coil bobbin expands the high frequency response.
  • 3-­point gluing which glues the cone paper, damper and the voice coil at one point is  employed on the FF-­WK series. Increasing the strength of the cone neck section realizes an improved high frequency response. Employing the pocket shape at the damper neck section has realized the 3-­point gluing even with the usage of junction cable.
  • In order to minimize the sound variation, the Faston 205 gold coating connection terminal is employed as a speaker terminal.

Short data

Usage as Fullrange
Power Handling 15 Watt
Impedance 8 Ohm
Frequency from 115 Hz
Max. Frequency 28 kHz
Sound pressure 86.5 dB


Overall dimensions 83 mm
Baffle cutout 73 mm
Depth (Total) 46.7 mm
Frame Material Steel plate
Membrane Type Cone
Membrane Material Kenaf Fibre
Dustcap Material Aluminium
Voice coil Ø 16 mm
Magnet Ø 70 mm
Magnet-height 15 mm
Magnet-weight 187 g
Magnet-inductance 3.93 T


Resonance fs fs: 115 Hz
Mechanical Q Qms: 3.298
Electrical Q Qes: 0.683
Total Q Qts: 0.55
Equivalent Air-Volumen Vas: 1.036 Liter
DC-Resistance Re: 7.2 Ohm
Coil Inductance Le: 0.032 mH
Mech. Compliance Cms: 0.909 mm/N
Moving Mass Mms: 2 g
Max. Excursion +/- Xmax: 0.35 mm
BL Product Bl: 3.93 N/A
Membrane Area Sd: 28 cm²
Sound pressure dB: 86.5 SPL
Efficiency Nref: 0.246 %

FF-WK Technology

Frequency & Impedance

Technical Dimensions

PDF-Product information

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