The 4¾” transducers WF120BD03 (4 ohm) and WF120BD04 (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 WF120BD03 and WF120BD07 is the shape of the mounting flange of the frames. WF120BD04 and WF120BD08 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
- Black coated semi-air-dried paper cone
- Rigid die cast alu chassis with extensive venting for lower air flow speed reducing audible distortion
- Large motor for better control and power handling
- Vented voice coil former 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
- 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
WF120BD03 /
WF120BD07WF120BD04 /
WF120BD08Unit
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
4
4
[kHz]
1
Sensitivity, 2.83V/1m (average SPL in range 300 - 1,000 Hz)
88.5
86
[dB]
2
Power handling, short term, IEC 268-5, no additional filtering
[W]
2
Power handling, long term, IEC 268-5, no additional filtering
[W]
2
Power handling, continuous, IEC 268-5, no additional filtering
50
50
[W]
Effective radiating area, Sd
54
54
[sq.cm]
3, 6
Resonance frequency (free air, no baffle), Fs
70
61.5
71.5
63
[Hz]
Moving mass, incl. air (free air, no baffle), Mms
6.55
6.25
[g]
3
Force factor, Bxl
4.5
5.5
[N/A]
3, 6
Suspension compliance, Cms
0.79
1.03
0.79
1.03
[mm/N]
3, 6
Equivalent air volume, Vas
3.25
4.25
3.25
4.25
[lit.]
3, 6
Mechanical resistance, Rms
0.49
0.42
0.49
0.42
[Ns/m]
3, 6
Mechanical Q, Qms
5.9
6.0
5.7
5.9
[-]
3, 6
Electrical Q, Qes
0.46
0.40
0.56
0.49
[-]
3, 6
Total Q, Qts
0.42
0.37
0.51
0.45
[-]
4
Voice coil resistance, RDC
3.2
6.0
[ohm]
5
Voice coil inductance, Le (measured at 10 kHz)
0.086
0.14
[mH]
Voice coil inside diameter
26
26
[mm]
Voice coil winding height
12
12
[mm]
Air gap height
4
4
[mm]
Magnet weight
430
430
[g]
Total unit net weight excl. packaging
1.04
1.04
[kg]
3, 5
Krm
27
33
[mohm]
3, 5
Erm
0.43
0.44
[-]
3, 5
Kxm
198
430
[mH]
3, 5
Exm
0.17
0.14
[-]
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