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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