1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationSound system equipment Electroacoustic transducers Measurement of large signal parametersBS EN 62458:2011National forewordThis British Standard is the UK implementation of EN 624
2、58:2011. It is identical to IEC 62458:2010.The UK participation in its preparation was entrusted to Technical CommitteeEPL/100, Audio, video and multimedia systems and equipment.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not
3、 purport to include all the necessary provisions of acontract. Users are responsible for its correct application. BSI 2011 ISBN 978 0 580 62423 0 ICS 33.160.50Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of t
4、he Standards Policy and Strategy Committee on 30 June 2011.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS EN 62458:2011EUROPEAN STANDARD EN 62458 NORME EUROPENNE EUROPISCHE NORM March 2011 CENELEC European Committee for Electrotechnical Standardization Comit Europen
5、 de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 62458:2011 E ICS 33.160.50 English ver
6、sion Sound system equipment - Electroacoustic transducers - Measurement of large signal parameters (IEC 62458:2010) Equipements pour systmes lectroacoustiques - Transducteurs lectroacoustiques - Mesure des paramtres en grand signal (CEI 62458:2010) Elektroakustische Gerte - Elektroakustische Wandler
7、 - Messung von Grosignal-Parametern (IEC 62458:2010) This European Standard was approved by CENELEC on 2011-01-02. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without
8、any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language m
9、ade by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
10、 Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 62458:2011EN 62458:2011 - 2 - Foreword The tex
11、t of document 100/1624/FDIS, future edition 1 of IEC 62458, prepared by IEC/TC 100, Audio, video and multimedia systems and equipment, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62458 on 2011-01-02. Attention is drawn to the possibility that some of the elements
12、 of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication of an identical national standard or
13、by endorsement (dop) 2011-10-02 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2014-01-02 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 62458:2010 was approved by CENELEC as a European Standard with
14、out any modification. _ BS EN 62458:2011- 3 - EN 62458:2011 Annex ZA (normative) Normative references to international publications with their corresponding European publications The following referenced documents are indispensable for the application of this document. For dated references, only the
15、 edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies. Publication Year Title EN/HD Year IEC 60
16、268-1 - Sound system equipment - Part 1: General HD 483.1 S2 - IEC 60268-5 A1 2003 2007 Sound system equipment - Part 5: Loudspeakers EN 60268-5 A1 2003 2009 BS EN 62458:2011 2 62458 IEC:2010(E) CONTENTS INTRODUCTION.6 1 Scope.7 2 Normative references .7 3 Terms and definitions .7 4 Test signals 9 4
17、.1 General .9 4.2 Large d.c. signal9 4.3 Large d.c. signal and small a.c. signal .9 4.4 Broadband noise signal .9 4.5 Music 9 5 Mounting condition .10 5.1 Drive units .10 5.2 Loudspeaker systems10 6 Climatic conditions .10 7 Acoustical environment 10 8 Preconditioning 10 9 Time-varying properties of
18、 the loudspeaker 11 10 Methods of measurement .11 10.1 General .11 10.2 Static or quasi-static method .11 10.3 Point-by-point dynamic method .12 10.4 Full dynamic method .14 11 Nonlinear force factor .15 11.1 Force factor curve Bl(x) .15 11.2 Force-factor limited displacement, XBl.16 11.3 Symmetry p
19、oint, xsym(xac)17 11.4 Voice coil offset, xoffset 18 12 Nonlinear stiffness18 12.1 Nonlinear stiffness curve Kms(x) 18 12.2 Compliance-limited displacement xC 19 12.3 Stiffness asymmetry AK(xpeak)19 13 Displacement-dependent inductance, Le(x).20 13.1 Inductance curve Le(x) 20 13.2 Inductance-limited
20、 displacement, xL 21 14 Current -dependent inductance, Le(i)21 14.1 Characteristic to be specified 21 14.2 Method of measurement 21 15 Parameters derived from geometry and performance 22 15.1 Maximal peak displacement, xMAXd .22 15.2 Method of measurement 22 Bibliography23 Figure 1 Electro-dynamical
21、 transducer .7 BS EN 62458:201162458 IEC:2010(E) 3 Figure 2 Static and quasi-static measurement setup . 12 Figure 3 Setup for measurement of large signal parameters by using the point-by-point dynamic method .13 Figure 4 Setup for dynamic measurement of large signal parameters.14 Figure 5 Reading th
22、e maximal peak displacement xBlimited by force factor only .16 Figure 6 Reading the voice coil offset from the symmetry point xsym(xac) curve 17 Figure 7 Definition of the symmetry point xsymin the nonlinear force factor characteristic Bl(x) 18 Figure 8 Reading the stiffness asymmetry from the Kms(x
23、) curve .20 BS EN 62458:2011 6 62458 IEC:2010(E) INTRODUCTION Electro-mechanical-acoustical transducers such as loudspeaker drive units, loudspeaker systems, headphones, micro-speakers, shakers, and other actuators behave in a nonlinear manner at higher amplitudes. This limits the acoustical output
24、and generates nonlinear signal distortion. Linear models fail in describing the large signal behaviour of such transducers and extended models have been developed which consider dominant nonlinearities in the motor and suspension. The free parameters of the large signal model have to be measured on
25、the particular transducer by using static or dynamic methods. The large signal parameters show the physical cause of the signal distortion directly and are very important for the objective assessment of sound quality and failure diagnostics in development and manufacturing. Furthermore, the model an
26、d parameters identified for a particular transducer are the basis for predicting the maximum output and signal distortion for any input signal. The close relationship between causes and symptoms simplifies the interpretation of the harmonic and intermodulation distortion measured according to IEC 60
27、268-5. Large signal parameters are valuable input data for the synthesis of loudspeaker systems and the development of electrical control systems dedicated to loudspeakers. BS EN 62458:201162458 IEC:2010(E) 7 SOUND SYSTEM EQUIPMENT ELECTROACOUSTICAL TRANSDUCERS MEASUREMENT OF LARGE SIGNAL PARAMETERS
28、 1 Scope This International Standard applies to transducers such as loudspeaker drive units, loudspeaker systems, headphones, micro-speakers, shakers and other actuators using either an electro-dynamical or electro-magnetic motor coupled with a mechanical suspension. The large signal behaviour of th
29、e transducer is modelled by a lumped parameter model considering dominant nonlinearities such as force factor, stiffness and inductance as shown in Figure 1. The standard defines the basic terms and parameters of the model, the methods of measurements and the way the results should be reported. 2 No
30、rmative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60268-1, Sound system equi
31、pment Part 1: General IEC 60268-5:2003, Sound system equipment Part 5: Loudspeakers Amendment 1 (2007) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 electro-mechanical equivalent circuit electrical circuit of an electro-dynamical transducer
32、, as shown in Figure 1 Re(TV) Le(x, i) i i3L2(x, i3) i2R2(x, i2) u Bl(x) v Bl(x) Bl(x) i vFm Cms(x) MmsRmsZloadIEC 2511/09 NOTE 1 This Figure shows an example of a lumped parameter model of an electro-dynamical transducer considering the dominant nonlinearities. NOTE 2 Other equivalent circuits can
33、be applied. Contrary to the results of linear modelling some parameters of the lumped elements are not constant but depend on instantaneous state variables (such as displacement x, velocity v, current i). Figure 1 Electro-dynamical transducer BS EN 62458:2011 8 62458 IEC:2010(E) 3.2 input current an
34、d voltage i, u electrical state variables at the terminals of the transducer 3.3 displacement x deflection of the voice coil from the rest position 3.4 velocity v time derivative of displacement x 3.5 d.c. resistance Reelectrical impedance Ze(s) at very low frequencies where the effect of the back E
35、MF can be neglected NOTE Electrical impedance can be used for measuring the d.c. resistance Reof the voice coil. The d.c. resistance Redepends on the mean voice coil temperature TV.3.6 nonlinear inductance and losses nonlinear elements to model the effect of the magnetic a.c. field, the losses in th
36、e magnetic material, and the losses caused by eddy currents where the equivalent circuit in Figure 1 uses the LR-2 model comprising the inductance Le(x, i), the inductance L2(x, i2) and additional resistance R2(x, i3) 3.7 nonlinear force factor Bl(x) dependency of instantaneous force factor Bl(x) on
37、 voice coil displacement x defined by the integral of magnetic flux density B versus the voice-coil conductor of length l NOTE The product of force factor Bl(x) and velocity v is the back EMF generated on the electrical side in an equivalent circuit as shown in Figure 1. The product of force factor
38、Bl(x) and input current i gives the electro-dynamical driving force of the mechanical system. 3.8 reluctance force Fmadditional electro-magnetic driving force caused by the displacement varying inductances Le(x, i) and L2(x, i2) 3.9 stiffness, Kms(x), of the suspension ratio between the instantaneou
39、s restoring force F(x) and the displacement x as given by ( ) ( )xxFxK =ms (1) NOTE The nonlinear compliance Cms(x) = 1/Kms (x) is the reciprocal quantity of the mechanical stiffness. BS EN 62458:201162458 IEC:2010(E) 9 3.10 mechanical mass Mmstotal moving mass including the mass of the moving assem
40、bly and the reactive part of the air load on both sides of the diaphragm 3.11 mechanical resistance Rmsnon-electrical losses of the driver, due to suspension, turbulences and radiation 3.12 mechanical impedance Zloadmechanical impedance which may represent any additional load caused by mechanical el
41、ements (cone, panel) or acoustical elements (such as a vented enclosure or horn) 4 Test signals 4.1 General The measurement of the large signal parameters requires an electrical, mechanical or acoustical stimulus. Depending on the method used for the measurement of the large signal parameters differ
42、ent kind of test signals are used as stimulus for the excitation of the transducer. Since the loudspeaker behaves as a time-varying system the stimulus may cause a permanent or temporary change of the loudspeaker properties. Thus, the properties of the stimulus (spectral bandwidth, crest factor, pro
43、ability density function) shall be statet. The same stimulus should be used if the numerical values of the results should be compared from two measurements. 4.2 Large d.c. signal A constant d.c. voltage or d.c current of defined magnitude and sufficient duration is supplied to the electrical termina
44、ls to measure the steady-state response of the transducer. If the transducer is mounted in a sealed enclosure a difference between the static air pressures inside and outside the enclosure may be used as d.c. stimulus. 4.3 Large d.c. signal and small a.c. signal A constant d.c. signal of defined mag
45、nitude and sufficient duration (see 4.2) superimposed with a small a.c. signal is used as stimulus. The a.c. signal (such as noise, sinusoidal sweep, impulsive test signals) should have sufficient bandwidth to identify all parameters of the loudspeaker model. 4.4 Broadband noise signal One of the no
46、ise signals defined in IEC 60268-1 or any other noise having sufficient bandwidth and amplitude may be used as stimulus. The crest factor of the noise should be less than 4 to reduce clipping in the amplifier. 4.5 Music Ordinary music, speech of sufficient bandwidth and amplitude may be used as a st
47、imulus. NOTE The dynamic methods need a stimulus which provides persistent excitation of the loudspeaker to identify the parameters correctly. The stimulus should have enough spectral components at least one octave below resonance frequency fsand one decade above fs. BS EN 62458:2011 10 62458 IEC:20
48、10(E) 5 Mounting condition 5.1 Drive units The driver unit may be mounted a) in free air without a baffle or enclosure, b) in a standard baffle according to 11.1 of IEC 60268-5, c) in half-space free field according to 5.2 of IEC 60268-5, d) in the standard measuring enclosure (type A or type B) acc
49、ording to 11.2 of IEC 60268-5, or another, specified enclosure, e) in vacuum, f) other configuration defined in the presentation of the results. The acoustic loading depends upon the mounting arrangement, which shall be clearly described in the presentation of the results. During the measurement the transducer should be firmly clamped to suppress additional mechanical resonances close to the resonance frequency fs. A vertical position of the transducer (cone displacemen
