| Brand | Fostex |
| Model | BK85WK |
| Kind | Woofer |
| Nominal diameter (mm) | |
| Impedance (Ω) | |
| Rated power (W) | |
| Maximum power (W) | |
| Sensitivity (dB, 1 W/1 m) | |
| Frequency response | |
| Resonance frequency, fs (Hz) | |
| DC resistance, Re (Ω) | |
| Mechanical Q, Qms | |
| Electrical Q, Qes | |
| Total Q, Qts | |
| Equivalent volume, Vas (l) | |
| Effective piston area, Sd (cm²) | |
| Moving mass, Mms (g) | |
| Force factor, BL (T·m) | |
| Voice coil inductance, Le (mH) | |
| Linear excursion, Xmax (mm) | |
| Excursion limit, Xmech (mm) | |
| Voice coil diameter (mm) | |
| Cutout diameter (mm) | 4000 |
| Mounting depth (mm) | |
| Cone material | |
| Magnet material | |
| Weight (kg) | 1.7 |
