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- 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
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FREQUENCY RESPONSE
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Downloads
SPL and impedance response curves as text files
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MR120BD01/03 SPL response
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MR120BD01/03 impedance response
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MR120BD02/04 SPL response
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MR120BD02/04 impedance response
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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.
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NOMINAL SPECIFICATIONS
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Notes
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Parameter
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MR120BD01/03
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MR120BD02/04
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Unit
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Before burn-in
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After burn-in
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Before burn-in
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After burn-in
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Nominal size
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4.75
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4.75
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[inch.]
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Nominal impedance
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4
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8
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[ohm]
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Recommended frequency range
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200 - 4,000
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200 - 4,000
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[Hz]
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1, 4
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Sensitivity, 2.83V/1m (average SPL in range 300 - 2,000 Hz)
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89
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86
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[dB]
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2, 4
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Power handling, short term, IEC 268-5, HP 200Hz@6dB/oct.
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550
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550
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[W]
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2, 4
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Power handling, long term, IEC 268-5, HP 200Hz@6dB/oct.
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125
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125
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[W]
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2, 4
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Power handling, continuous, IEC 268-5, HP 200Hz@6dB/oct.
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55
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55
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[W]
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Effective radiating area, Sd
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50
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50
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[sq.cm]
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3, 4, 6
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Resonance frequency (free air, no baffle), Fs
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72
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70
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73
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72
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[Hz]
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Moving mass, incl. air (free air, no baffle), Mms
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5.7
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5.5
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[g]
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3, 4
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Force factor, Bxl
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4.2
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5.2
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[N/A]
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3, 4, 6
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Suspension compliance, Cms
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0.87
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0.90
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0.87
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0.90
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[mm/N]
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3, 4, 6
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Equivalent air volume, Vas
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3.1
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3.2
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3.1
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3.2
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[lit.]
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3, 4, 6
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Mechanical resistance, Rms
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0.30
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0.30
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0.30
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0.30
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[Ns/m]
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3, 4, 6
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Mechanical Q, Qms
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8.5
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8.4
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8.3
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8.3
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[-]
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3, 4, 6
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Electrical Q, Qes
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0.47
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0.46
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0.60
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0.59
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[-]
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3, 4, 6
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Total Q, Qts
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0.45
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0.44
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0.56
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0.55
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[-]
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4
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Voice coil resistance, RDC
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3.2
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6.4
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[ohm]
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5
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Voice coil inductance, Le (measured at 10 kHz)
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[mH]
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Voice coil inside diameter
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[mm]
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Voice coil winding height
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7
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7
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[mm]
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Air gap height
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4
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4
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[mm]
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Theoretical linear motor stroke, Xmax
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+/-1.5
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+/-1.5
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[mm]
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Magnet weight
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440
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440
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[g]
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Total unit net weight excl. packaging
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1.1
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1.1
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[kg]
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3, 4, 5
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Krm
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[mohm]
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3, 4, 5
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Erm
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[-]
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3, 4, 5
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Kxm
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[mH]
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3, 4, 5
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Exm
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[-]
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Note 1
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Measured in infinite baffle.
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Note 2
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Tested in free air (no cabinet).
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Note 3
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Measured using a semi-constant current source, nominal level 2 mA.
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Note 4
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Measured at 25 deg. C
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Note 5
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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.
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Note 6
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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.
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HARMONIC DISTORTION
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OUTLINE DRAWING AND NOMINAL DIMENSIONS (mm)
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Part no. MR120BD01-01
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4 ohm version, round, individual packaging (one piece per box)
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Part no. MR120BD01-02
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4 ohm version, round, bulk packaging
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Part no. MR120BD02-01
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8 ohm version, round, individual packaging (one piece per box)
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Part no. MR120BD02-02
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8 ohm version, round, bulk packaging
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Part no. MR120BD03-01
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4 ohm version, truncated, individual packaging (one piece per box)
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Part no. MR120BD03-02
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4 ohm version, truncated, bulk packaging
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Part no. MR120BD04-01
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8 ohm version, truncated, individual packaging (one piece per box)
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Part no. MR120BD04-02
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8 ohm version, truncated, bulk packaging
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Latest update: March 1, 2024
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Specifications are subject to change without any further notice.
Copyright © 2006-2023 by Wavecor Ltd., China. All rights reserved.
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MORE INFO
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 PDF data sheet
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Balanced Drive technical paper
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