1、BRITISH STANDARD BS6840-2: 1993 IEC268-2: 1987 (including Amendment No.1 May1991 to IEC268-2:1987) Sound system equipment Part 2: Glossary of general terms and calculation methods (Implementation of CENELECHD483.2S2) UDC 534.86:621.39:001.4BS6840-2:1993 This British Standard, having been prepared un
2、der the directionof the Electronic Equipment Standards Policy Committee, was published underthe authority of the Standards Board and comes intoeffect on 15 November1993 BSI 07-1999 First published August1988 Second edition November1993 The following BSI references relate to the work on this standard
3、: Committee reference EEL/32 Draft for comment84/28116 DC and DC89/21657 DC ISBN 0 580 22345 0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Power Electrical Engineering Standards Policy Committee (EEL/-) to Technical Committee EEL/32,
4、 upon which the following bodies were represented: Association of British Theatre Technicians Association of Electronics, Telecommunications and Business Equipment Industries Audio Engineering Society British Broadcasting Corporation British Educational Equipment Association British Kinematograph, S
5、ound and Television Society British Radio and Electronic Equipment Manufacturers Association British Telecommunications plc Consumers Association Electronic Components Industry Federation Federation of British Audio Independent Television Association Institution of Electrical Engineers International
6、 Association of Broadcasting Manufacturers National Council for Educational Technology (NCET) Professional Lighting and Sound Association Radio Electrical and Television Retailers Association Royal Institute of British Architects Royal National Institute for Deaf People Society of Cable Television E
7、ngineers Sound and Communication Industries Federation Amendments issued since publication Amd. No. Date CommentsBS6840-2:1993 BSI 07-1999 i Contents Page Committees responsible Inside front cover National foreword ii Foreword 2 1 General terms 3 1.1 Sound system 3 1.2 Compatibility 3 1.3 Variable c
8、onsumption apparatus 3 1.4 Noise signal 3 1.5 Rated values 3 2 Power 4 2.1 Relative power level 4 2.2 Power level 4 2.3 Available power from the source 4 2.4 Available power gain 4 3 Voltage 4 3.1 Relative voltage level 4 3.2 Voltage level 4 3.3 Voltage gain 5 3.4 E.M.F. gain (overall voltage gain)
9、5 4 Source e.m.f. 5 4.1 Equivalent source e.m.f 5 5 Balance 5 5.1 Balanced circuits 5 5.2 Balanced inputs 5 5.3 Balanced outputs 5 6 Noise 6 6.1 Noise voltage 6 6.2 Signal-to-noise ratio 6 6.3 Equivalent noise source e.m.f. 6 7 Amplitude non-linearity 6 7.1 Introduction 6 7.2 Explanation of terms 6
10、7.3 Elucidation 7 8 Cross-talk and separation in multi-channel equipment 8 8.1 General 8 8.2 Cross-talk attenuation (from A to B) 8 8.3 Separation (of A from B) 8 9 Acoustic characteristics 8 9.1 Sound pressure level 8 9.2 Sound power level 8 9.3 Equivalent input sound pressure of a microphone 8 10
11、Polarity 8 10.1 Characteristics to be specified 9 10.2 Method of measurement 9 Annex ZA (normative) Other international publications quoted in this standardwith the references of the relevant European publications 13 National annex NA (informative) Cross-references Inside back coverBS6840-2:1993 ii
12、BSI 07-1999 Page Figure 1 Balance of the input 9 Figure 2 Balance of the output 10 Figure 3 Distortion spectra 11 Figure 3a Harmonic distortion 11 Figure 3b Modulation distortion 11 Figure 3c Difference-frequency distortion 12 Figure 3d Total difference-frequency distortion 12BS6840-2:1993 BSI 07-19
13、99 iii National foreword This Part of BS6840 has been prepared under the direction of the Electronic Equipment Standards Policy Committee. It is identical with IEC268-2:1987 Sound system equipment Part2: Explanation of general terms and calculation methods, as amended by Amendment No.1 (May1991), pu
14、blished by the International Electrotechnical Commission (IEC). This British Standard implements Harmonization Document HD483.2 S2:1993, published by the European Committee for Electrotechnical Standardization (CENELEC). This British Standard supersedes BS6840-2:1988 which is withdrawn. This edition
15、 introduces technical changes to bring this standard up-to-date but does not reflect a full review of the standard, which will be undertaken in due course. The changes introduced by the IEC Amendment No.1 are indicated by a sideline in the margin. BS6840 consists of the following Parts: Part 1: Meth
16、ods for specifying and measuring general characteristics used for equipment performance; Part 2: Glossary of general terms and calculation methods; Part 3: Methods for specifying and measuring the characteristics of sound system amplifiers; Part 4: Methods for specifying and measuring the characteri
17、stics of microphones; Part 5: Methods for specifying and measuring the characteristics of loudspeakers; Part 6: Methods for specifying and measuring the characteristics of auxiliary passive elements; Part 7: Methods for specifying and measuring the characteristics of headphones and earphones 1) ; Pa
18、rt 8: Methods for specifying and measuring the characteristics of automatic gain control devices; Part 9: Methods for specifying and measuring the characteristics of artificial reverberation time delay and frequency shift equipment; Part 10: Methods for specifying and measuring the characteristics o
19、f peak programme level meters; Part 11: Specification for application of connectors for the interconnection of sound system components; Part 12: Specification for applications of connectors for broadcast and similar use; Part 13: Guide for listening tests on loudspeakers; Part 14: Guide for circular
20、 and elliptical loudspeakers; outer frame diameters and mounting dimensions; Part 15: Specification for matching values for the interconnection of sound system components; Part 16: Guide to the “RASTI” method for the objective rating of speech intelligibility in auditoria; Part 17: Methods for speci
21、fying and measuring the characteristics of standard volume indicators. 1) In preparation.BS6840-2:1993 iv BSI 07-1999 Additional information Scope. IEC268-2 does not give the scope of the standard, which for the purposes of this British Standard is as follows: “This Part of BS6840 specifies general
22、terms and calculation methods for sound system equipment”. References to page numbers in the text relate to the IEC page numbers given in brackets at the bottom of each page. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are res
23、ponsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pagesi toiv, theHDtitle page, pages2 to14, an inside back cover and a back cover. This
24、standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.HARMONIZATION DOCUMENT DOCUMENT DHARMONISATION HARMONISIERUNGSDOKUMENT HD483.2S2 February1993 UDC 534.86:621.39:001.4 Descriptors: Sound sy
25、stem equipment, definition, general, calculation methods English version Sound system equipment Part2:Explanation of general terms and calculation methods (IEC268-2:1987+A1:1991) Equipements pour systmes lectroacoustiques Deuxime partie: Explication des termes gnraux et mthodes de calcul (CEI268-2:1
26、987+A1:1991) Elektroakustische Gerte Teil2: Allgemeine Begriffe und Berechnungsverfahren (IEC268-2:1987+A1:1991) This Harmonization Document was approved by CENELEC on1992-12-09. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for implemen
27、tation of this Harmonization Document on a national level. Up-to-date lists and bibliographical references concerning national implementation may be obtained on application to the Central Secretariat or to any CENELEC member. This Harmonization Document exists in three official versions (English, Fr
28、ench, German). CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland andUnited Kingdom. CENELEC European Committee for Electrotechnica
29、l Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 Brussels 1993 Copyright reserved to CENELEC members Ref. No. HD483.2 S2:1993 EBS6840-2:1993 BSI 07-1999 2 Foreword The CENELEC questionna
30、ire procedure, performed for finding out whether or not the International Standard IEC268-2:1987 and its amendment1:1991 could be accepted without textual changes, has shown that no common modifications were necessary for the acceptance as Harmonization Document. The reference document was submitted
31、 to the CENELEC members for formal vote and was approved by CENELEC as HD483.2 S2 on9December1992. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. In this standard, Annex ZA is normative. latest date of announcement of the HD at national level (do
32、a)1993-06-01 latest date of publication of aharmonized national standard (dop)1993-12-01 latest date of withdrawal of conflicting national standards (dow)1993-12-01BS6840-2:1993 BSI 07-1999 3 For the purpose of this standard, the following explanations of general terms and calculation methods apply:
33、 1 General terms 1.1 Sound system An assembly of equipment which in combination enables sound signals or audio-frequency signals to be processed or transmitted. Such equipment may be, for example, transducers, amplifiers, recorders, etc. 1.2 Compatibility A component of a system is said to be compat
34、ible with another component if, when they are connected together, satisfactory operation is obtained. 1.3 Variable consumption apparatus An apparatus in which the power drawn from the supply system may vary significantly during operation, as a function of the signal or the load impedance or of the c
35、ontrol settings (excluding power supply switches). NOTEFor some purposes, changes of less than15% may be insignificant. 1.4 Noise signal A stationary random signal having normal probability distribution of instantaneous values. Unless otherwise stated, the mean value is zero. NOTEThis explanation ap
36、plies to noise signals used for testing. Noise as an unwanted signal is considered in Clause6. 1.4.1 White noise signal A noise signal whose energy per unit bandwidthis independent of frequency. 1.4.2 Pink noise signal A noise signal whose energy per unit bandwidthis inversely proportional to freque
37、ncy. 1.4.3 Broadband noise signal A noise signal, band-limited by means of a filter with defined amplitude/frequency response whose bandwidth is greater than that of the equipment under test. NOTEA broadband noise signal may be a band-limited white or pink noise signal, or have some other defined po
38、wer spectrum. 1.4.4 Narrowband noise signal A noise signal, band-limited by means of a filter with defined amplitude/frequency response, whose bandwidth is small compared with that of the equipment under test. 1.5 Rated values In this standard, the term “rated value” is used in a particular sense. W
39、herever it is used it means “the value stated by the manufacturer”. The word “rated” has this meaning even though it is used in terms such as “rated conditions” or in the name of a characteristic. 1.5.1 Rated conditions When an equipment is to be used or tested it has to be operated under certain co
40、nditions which are fixed by the manufacturer. These conditions include electrical, mechanical and climatic conditions, and they cannot, by their nature, be verified by measurement. Rated conditions for a particular type of equipment generally include some or all of the following: Electrical Rated po
41、wer supply voltage(s) Rated power supply frequency Rated source impedance(s) Rated source e.m.f.(s) Rated load impedance(s) Mechanical Mounting position Ventilation Climatic Rated ambient temperature ranges for operation and for full performance to specification Rated relative humidity range Rated a
42、ir pressure range NOTERanges are defined by the extreme values, each of which may be regarded as a separate rated condition. 1.5.2 Rated value of a characteristic In IEC Publication 268, methods of measurement are given for a large number of characteristics. For each of these characteristics the man
43、ufacturer is required or permitted to state a value in the specification of equipment. This stated value is, by definition, the rated value of that characteristic (see Sub-clause1.5). The use of the term “rated” in this sense is not restricted to a limited set of major characteristics but may be app
44、lied to any characteristic for which a method of measurement is given. Since the rated value is the value stated by the manufacturer, the defining title of the “characteristic to be specified” does not, in general, include the word “rated”; the rated value is not something which is measured but is d
45、ecided by the manufacturer taking into account measurements on many samples of the equipment and theoretical tolerance calculations. %W % f - %W % f - BS6840-2:1993 4 BSI 07-1999 For example, a method of measurement is described in IEC Publication268-3 for the distortion-limited output power of an a
46、mplifier. The rated distortion-limited output power is the value stated by the manufacturer, usually calculated from measurements (according to the standard method) on several samples of the amplifier, supplemented by tolerance calculation. NOTEApplies to French text only. 1.5.3 Interdependent chara
47、cteristics It often happens that the value of one characteristic is required to be stated for a particular value of another characteristic. An important example is the distortion-limited output power of an amplifier, which is stated for a particular value of total harmonic distortion. In this case i
48、t is necessary to adopt one of the characteristics as a rated condition, and it is preferable to adopt that characteristic whose rated value is either specified as a reference value in a relevant IEC standard or is chosen by the manufacturer more or less arbitrarily within certain practical limits.
49、1.5.4 Matching values A knowledge of the values of certain basic characteristics of two items of equipment, which are to be connected together, is necessary in order to ensure compatability. These values are known as matching values and are stated by the manufacturer for conditions defined in the relevant parts of the standard. Some matching values are also rated conditions. 2 Power 2.1 Relative power level Ten times the logarithm to base ten of
