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Thumbnail Filmstrip of Wavecor WF120BD05 - 4 Ohm Die Cast Paper Glass Fibre Mid-Woofer Images
Wavecor Speaker Driver - WF120BD05 - 4 Ohm Die Cast Paper/Glass Fibre Mid-Woofer
Description
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.
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
- 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
Frequency SPL and Impedance Response Graphs
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 max upper frequency limit |
3.5 | kHz | ||
| 1, 4 | Sensitivity, 2.83V/1m (average SPL in range 300 - 1000 kHz) | 87 | dB | |
| 2 | Power handling, short term, IEC 268-5, 6 kHz, no additonal filtering. | 150 | W | |
| 2 | Power handling, long term, IEC 268-5, 6 kHz, no additonal filtering. | W | ||
| 2 | Power handling, continuous, IEC 268-5, 6 kHz, no additonal filtering. | 60 | W | |
| Effective radiating area, Sd | 54 | cm2 | ||
| 3, 4, 6 | Resonance frequency (free air, no baffle), Fs | 52 | 48 | Hz |
| Moving mass, incl. air (free air, no baffle), Mms | 7.3 | g | ||
| 3 | Force factor, Bxl | 4.1 | - | |
| 3, 4, 6 | Suspension compliance, Cms | 1.29 | 1.50 | mm/N |
| 3, 4, 6 | Equivalent air volume, Vas | 5.3 | 6.2 | ml |
| 3, 4, 6 | Mechanical resistance, Rms | 0.30 | 0.30 | Ns/m |
| 3, 4, 6 | Mechanical Q, Qms | 7.9 | 7.4 | - |
| 3, 4, 6 | Electrical Q, Qes | 0.45 | 0.42 | - |
| 3, 4, 6 | Total Q, Qts | 0.43 | 0.40 | - |
| 4 | Voice coil resistance, RDC | 3.2 |
Ohm | |
| 5 | Voice coil inductance, Le (measured at 10 kHz) | 0.087 | mH | |
| Voice coil inside diameter | 32 | mm | ||
| Voice coil winding height | 12 | mm | ||
| Air gap height | 4 | mm | ||
| Theoretical linear motor stroke, Xmax | ±4 | mm | ||
| Magnet weight | 370 | g | ||
| Total unit net weight excl. packaging | 1.05 | kg | ||
| 3, 4, 5 | Krm | 40 | mOhm | |
| 3, 4, 5 | Erm | 0.39 | - | |
| 3, 4, 5 | Kxm | 61 | mH | |
| 3, 4, 5 | Exm | 0.32 | - | |
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
Loudspeaker Driver Dimensions and Measurements - all dimensions in mm (approx.)
Terminal Nominal Dimensions
Loudspeaker Driver Terminal Dimensions and Measurements - all dimensions in mm (approx.)
Thickness, both terminals: 0.5 mm
Terminal plating: Gold