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Wavecor Speaker Driver - WF120BD03 - 4 Ohm 5" Die Cast Paper Cone Mid Woofer
Description
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.
Features
- 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
Frequency SPL and Impedance Response Graphs
![](/mm5/graphics/wavecor/wf120bd03_04_08/WF120BD03_07-SPL-_-IMP-resp.png)
Loudspeaker Frequency Response Graph
Measuring conditions, SPL
Driver mounting: Flush in infinite baffle
Microphone distance: 1.0 m
Input level: 2.83 VRMS
Smoothing: 1/6 oct.
Loudspeaker Impedance Response Graph
Measuring conditions, impedance
Driver mounting: Free air, no baffle
Input signal: Stepped sine wave, semi-current-drive, nominal current 2 mA
Smoothing: None
Technical Specifications
Notes | Parameter | Value | Unit | |
Before Burn-in |
After Burn-in | |||
Nominal size | 4¾ | Inch | ||
Nominal impedance | 4 | Ohm | ||
Recommended frequency range |
4 | kHz | ||
1 | Sensitivity, 2.83V/1m (average SPL in range 300 - 1000 kHz) | 88.5 | dB | |
2 | Power handling, short term, IEC 268-5, 6 kHz no additional filtering | W | ||
2 | Power handling, long term, IEC 268-5, 6 kHz no additional filtering | W | ||
2 | Power handling, continuous, IEC 268-5, 6 kHz no additional filtering | 50 | W | |
Effective radiating area, Sd | 50 | cm2 | ||
3, 6 | Resonance frequency (free air, no baffle), Fs | 70 | 61.5 | kHz |
Moving mass, incl. air (free air, no baffle), Mms | 6.55 | g | ||
3 | Force factor, Bxl | 4.5 | - | |
3, 6 | Suspension compliance, Cms | 0.79 | 1.03 | mm/N |
3, 6 | Equivalent air volume, Vas | 3.25 | 4.25 | ml |
3, 6 | Mechanical resistance, Rms | 0.49 | 0.42 | Ns/m |
3, 6 | Mechanical Q, Qms | 5.9 | 6.0 | - |
3, 6 | Electrical Q, Qes | 0.46 | 0.40 | - |
3, 6 | Total Q, Qts | 0.42 | 0.37 | - |
4 | Voice coil resistance, RDC | 3.2 | Ohm | |
5 | Voice coil inductance, Le (measured at 10 kHz) | 0.086 | uH | |
Voice coil inside diameter | 26 | mm | ||
Voice coil winding height | 12 | mm | ||
Air gap height | 4 | mm | ||
Magnet weight | 430 | g | ||
Total unit net weight excl. packaging | 1.04 | kg | ||
3, 5 | Krm | 27 | mOhm | |
3, 5 | Erm | 0.43 | - | |
3, 5 | Kxm | 198 | mH | |
3, 5 | Exm | 0.17 | - |
Note 2 Tested in free air (no cabinet).
Note 3 Measured using a semi-constant current source, nominal level 2 mA.
Note 4 Measured at 25 deg. C
Note 5 It is generally a rough simplification to assume that loudspeaker transducer voice coils exhibit the characteristics of an inductor. Instead it is a far more accurate approach to use the more advanced model often referred to as the “Wright empirical model”, also used in LEAP-4 as the TSL model (www.linearx.com), involving parameters Krm, Erm, Kxm, and Exm. This more accurate transducer model is described in a technical paper (PDF) here.
Note 6 After burn-in specifications are measured 12 hours after exiting the transducer by a 20 Hz sine wave for 2 hours at level 7.75/11 VRMS (4/8 ohm version). The unit is not burned in before shipping
Driver Nominal Dimensions
![](/mm5/graphics/wavecor/wf120bd03_04_08/WF120BD03_04-outline-drawing.png)
Loudspeaker Driver Dimensions and Measurements - all dimensions in mm (approx.)
Terminal Nominal Dimensions
![](/mm5/graphics/wavecor/wf120bd03_04/Terminals-dimensions.gif)
Loudspeaker Driver Terminal Dimensions and Measurements - all dimensions in mm (approx.)
Thickness, both terminals: 0.5 mm
Terminal plating: Gold