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WF120BD11/12/13/14     4¾” die cast, Kevlar/Carbon fibre cone mid/woofers

 

 

 

 

 

 

Balanced Drive

The 4.75” transducers WF120BD11 (round, 4 ohm), WF120BD13 (truncated, 4 ohm), WF120BD12 (round, 8 ohm), and WF120BD14 (truncated, 8 ohm) were designed as high performance bass and midrange units for compact monitors and high-end hi-fi speakers.

Frequency resp.
Downloads
Specifications
Harmonic distortion
Dimensions
Ordering info

FEATURES

Round versions WF120BD11, WF120BD12
Truncated versions WF120BD13, WF120BD14

  • New cone of interwoven Kevlar/Carbon fibers, a new reference for the combination of low mass, rigidness, and damping - highly beneficial properties for midrange reproduction
  • Balanced Drive motor structure for optimal drive force symmetry resulting in largely reduced even order harmonic distortion
  • Vented, inverted center dome for reduced compression
  • 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
  • Rigid die cast alu chassis with extensive venting for lower air flow speed reducing audible distortion
  • Heavy-duty black fiber glass voice coil former to reduce mechanical losses resulting in better dynamic performance and low-level details
  • Large motor with 1” 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 RESPONSE

WF120BD11/13 SPL response

Measuring conditions, SPL
Driver mounting: Flush in infinite
     baffle, back side open (no cabinet)
Microphone distance: 1.0 m
Input signal: 2.83 VRMS LogChirp, 64k, Hanning/2
Smoothing: 1/6 oct.

Measuring conditions, impedance
Driver mounting: Free air, no baffle,
     back side open (no cabinet)
Input signal: Stepped sine wave, semi-
     current-drive, nominal current 2 mA
Smoothing: None

WF120BD11/13 impedance response
WF120BD12/14 SPL response

Measuring conditions, SPL
Driver mounting: Flush in infinite
     baffle, back side open (no cabinet)
Microphone distance: 1.0 m
Input signal: 2.83 VRMS LogChirp, 64k, Hanning/2
Smoothing: 1/6 oct.

Measuring conditions, impedance
Driver mounting: Free air, no baffle,
     back side open (no cabinet)
Input signal: Stepped sine wave, semi-
     current-drive, nominal current 2 mA
Smoothing: None

WF120BD12/14 impedance response

Downloads
SPL and impedance response curves as text files

WF120BD11/13 SPL response

WF120BD11/13 SPL response

WF120BD11/13 impedance response

WF120BD11/13 impedance response

WF120BD12/14 SPL response

WF120BD12/14 SPL response

WF120BD12/14 impedance response

WF120BD12/14 impedance response

Important!
Please observe that these text files for download are actual measurements of the drivers measured in infinite baffle and without any enclosure. Measuring the drivers in a finite baffle (like the baffle of most speaker cabinets) and in any size of enclosure will lead to different response curves.

NOMINAL SPECIFICATIONS

Notes

  Parameter

WF120BD11/13

WF120BD12/14

Unit

Before burn-in

After burn-in

Before burn-in

After burn-in

 

Nominal size

4.75

4.75

[inch.]

 

Nominal impedance

4

8

[ohm]

 

Recommended max. upper frequency limit

4

4

[kHz]

1, 4

Sensitivity, 2.83V/1m (average SPL in range 300 - 2,000 Hz)

88

85

[dB]

2, 4

Power handling, short term, IEC 268-5, no additional filtering

400

400

[W]

2, 4

Power handling, long term, IEC 268-5, no additional filtering

120

120

[W]

2, 4

Power handling, continuous, IEC 268-5, no additional filtering

40

40

[W]

 

Effective radiating area, Sd

48

48

[sq.cm]

3, 4, 6

Resonance frequency (free air, no baffle), Fs

58

56.5

59

57.5

[Hz]

 

Moving mass, incl. air (free air, no baffle), Mms

6.6

6.4

[g]

3, 4

Force factor, Bxl

4.2

5.3

[N/A]

3, 4, 6

Suspension compliance, Cms

1.15

1.20

1.15

1.20

[mm/N]

3, 4, 6

Equivalent air volume, Vas

3.8

3.9

3.8

3.9

[lit.]

3, 4, 6

Mechanical resistance, Rms

0.25

0.25

0.25

0.25

[Ns/m]

3, 4, 6

Mechanical Q, Qms

9.6

9.4

9.5

9.3

[-]

3, 4, 6

Electrical Q, Qes

0.40

0.40

0.50

0.49

[-]

3, 4, 6

Total Q, Qts

0.39

0.38

0.47

0.46

[-]

4

Voice coil resistance, RDC

3.0

5.9

[ohm]

5

Voice coil inductance, Le (measured at 10 kHz)

 

 

[mH]

 

Voice coil inside diameter

25

25

[mm]

 

Voice coil winding height

10

10

[mm]

 

Air gap height

4

4

[mm]

 

Theoretical linear motor stroke, Xmax

+/-3

+/-3

[mm]

 

Magnet weight

440

440

[g]

 

Total unit net weight excl. packaging

1.1

1.1

[kg]

3, 4, 5

Krm

 

 

[mohm]

3, 4, 5

Erm

 

 

[-]

3, 4, 5

Kxm

 

 

[mH]

3, 4, 5

Exm

 

 

[-]

Note 1

Measured in infinite baffle.

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 at least 12 hours after exciting the transducer by a sine wave at the frequency of Fs for 2 hours at level 4/5 VRMS (4/8 ohm version). The unit is not burned in before shipping.
 

HARMONIC DISTORTION

WF120BD11/13 harmonic distortion

Measuring conditions, harmonic distortion
Driver mounting: In sealed enclosure, internal volume 2 lit.,
Microphone distance: 0.5 m
Input signal: Stepped sine wave, 4.7 VRMS (WF120BD11/13) / 6.3 VRMS (WF120BD12/14)
Smoothing: 1/12 oct.

WF120BD12/14 harmonic distortion

OUTLINE DRAWING AND NOMINAL DIMENSIONS (mm)

WF120BD11/12/13/14 outline drawing
WF120BD11_12_13_14-outline

TERMINAL NOMINAL DIMENSIONS (mm)

Terminal dimensions

PACKAGING AND ORDERING INFORMATION

Part no. WF120BD11-01

4 ohm version, round, individual packaging (one piece per box)

Part no. WF120BD11-02

4 ohm version, round, bulk packaging

Part no. WF120BD12-01

8 ohm version, round, individual packaging (one piece per box)

Part no. WF120BD12-02

8 ohm version, round, bulk packaging

Part no. WF120BD13-01

4 ohm version, truncated, individual packaging (one piece per box)

Part no. WF120BD13-02

4 ohm version, truncated, bulk packaging

Part no. WF120BD14-01

8 ohm version, truncated, individual packaging (one piece per box)

Part no. WF120BD14-02

8 ohm version, truncated, bulk packaging

Latest update: March 20, 2024

 

Specifications are subject to change without any further notice.
Copyright © by Wavecor Ltd., China. All rights reserved.

 

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MORE INFO

WF120BD11/12/13/14 specificationsPDF data sheet

 

Balanced Drive technical paperBalanced Drive technical paper

 

 

 

 

 

 

 

 

 

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