The 4¾” transducers WF120BD05/WF120BD09 (4 ohm) and WF120BD06/WF120BD10 (8 ohm) were designed as high performance bass and midrange units for very compact monitors and high-end hi-fi speakers.
The only difference between WF120BD05 and WF120BD09 is the shape of the mounting flange of the frames. WF120BD06 and WF120BD10 differ in the same way.
- Balanced Drive motor structure for optimal drive force symmetry resulting in largely reduced even order harmonic distortion
- Copper cap on center pole to reduce voice coil inductance and to minimize variations in voice coil inductance as a function of voice coil position
- Cone made of a new paper/glass fiber mix with improved consistency and stability
- Rigid die cast alu chassis with extensive venting for lower air flow speed reducing audible distortion
- Vented voice coil former for reduced distortion and compression
- Vented center pole with dual flares for reduced noise level at large cone excursions
- Heavy-duty black fiber glass voice coil former to reduce mechanical losses resulting in better dynamic performance and low-level details
- Large motor with 1¼” voice coil diameter for better control and power handling
- Built-in alu field-stabilizing ring for reduced distortion at high levels
- Low-loss suspension (high Qm) for better reproduction of details and dynamics
- Black motor parts for better heat transfer to the surrounding air
- Conex spider for better durability under extreme conditions
- Gold plated terminals to ensure long-term trouble free connection
Notes
Parameter | WF120BD05 / WF120BD09 | WF120BD06 / WF120BD10 | Unit | |||
Before burn-in | After burn-in | Before burn-in | After burn-in | |||
| Nominal size | 4¾ | 4¾ | [inch.] | ||
| Nominal impedance | 4 | 8 | [ohm] | ||
| Recommended max. upper frequency limit | 3.5 | 3.5 | [kHz] | ||
1, 4 | Sensitivity, 2.83V/1m (average SPL in range 300 - 1,000 Hz) | 87 | 84 | [dB] | ||
2, 4 | Power handling, short term, IEC 268-5, no additional filtering | 150 | 150 | [W] | ||
2, 4 | Power handling, long term, IEC 268-5, no additional filtering |
|
| [W] | ||
2, 4 | Power handling, continuous, IEC 268-5, no additional filtering | 60 | 60 | [W] | ||
| Effective radiating area, Sd | 54 | 54 | [sq.cm] | ||
3, 4, 6 | Resonance frequency (free air, no baffle), Fs | 52 | 48 | 54 | 50 | [Hz] |
| Moving mass, incl. air (free air, no baffle), Mms | 7.3 | 6.7 | [g] | ||
3 | Force factor, Bxl | 4.1 | 5.2 | [N/A] | ||
3, 4, 6 | Suspension compliance, Cms | 1.29 | 1.50 | 1.29 | 1.50 | [mm/N] |
3, 4, 6 | Equivalent air volume, Vas | 5.3 | 6.2 | 5.3 | 6.2 | [lit.] |
3, 4, 6 | Mechanical resistance, Rms | 0.30 | 0.30 | 0.30 | 0.30 | [Ns/m] |
3, 4, 6 | Mechanical Q, Qms | 7.9 | 7.4 | 7.6 | 7.0 | [-] |
3, 4, 6 | Electrical Q, Qes | 0.45 | 0.42 | 0.54 | 0.50 | [-] |
3, 4, 6 | Total Q, Qts | 0.43 | 0.40 | 0.50 | 0.47 | [-] |
4 | Voice coil resistance, RDC | 3.2 | 6.4 | [ohm] | ||
5 | Voice coil inductance, Le (measured at 10 kHz) | 0.087 | 0.16 | [mH] | ||
| Voice coil inside diameter | 32 | 32 | [mm] | ||
| Voice coil winding height | 12 | 12 | [mm] | ||
| Air gap height | 4 | 4 | [mm] | ||
| Theoretical linear motor stroke, Xmax | ±4 | ±4 | [mm] | ||
| Magnet weight | 370 | 370 | [g] | ||
| Total unit net weight excl. packaging | 1.05 | 1.05 | [kg] | ||
3, 4, 5 | Krm | 40 | 109 | [mohm] | ||
3, 4, 5 | Erm | 0.39 | 0.35 | [-] | ||
3, 4, 5 | Kxm | 61 | 145 | [mH] | ||
3, 4, 5 | Exm | 0.32 | 0.27 | [-] |
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