1、BRITISH STANDARD BS 5550-3.4.9: 1987 ISO 7831:1986 Cinematography Part 3: 35 mm film Section 3.4 Sound Subsection 3.4.9 Specification for reproduction characteristics of the A-chain frequency response for35mm photographic sound UDC 778.5.34.427BS5550-3.4.9:1987 This British Standard, having been pre
2、pared under the directionof the Cinematography and Photography Standards Committee, was published underthe authority of the BoardofBSI and comes into effecton 30 April 1987 BSI 10-1999 The following BSI references relate to the work on this standard: Committee reference CPM/5 Draft for comment 83/36
3、869 DC ISBN 0 580 15695 8 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Cinematography and Photography Standards Committee (CPM/-) to Technical Committee CPM/5, upon which the following bodies were represented: Association of Cinematog
4、raph, Television and Allied Technicians Association of Independent Cinemas British Broadcasting Corporation British Film and Television Producers Association British Film Institute British Kinematograph, Sound and Television Society Cinematograph Exhibitors Association of Great Britain and Ireland I
5、ndependent Television Companies Association Institute of Amateur Cinematographers Royal Photographic Society Amendments issued since publication Amd. No. Date of issue CommentsBS5550-3.4.9:1987 BSI 10-1999 i Contents Page Committees responsible Inside front cover National foreword ii 1 Scope and fie
6、ld of application 1 2 References 1 3 Definitions 1 4 Method of measurement 1 5 Characteristics 1 Annex A Overall A+B response for the replay of type 1 and type 3 photographicsound track 4 Figure 1 Complete sound reproducing system 2 Figure 2 A-chain characteristics for type1 photographic sound track
7、s 3 Figure 3 Overall A+B response 4 Table 1 A-chain frequency response for reproduction of35mm photographicsound 2 Table 2 Overall A+B response 4 Publications referred to Inside back coverBS5550-3.4.9:1987 ii BSI 10-1999 National foreword This Subsection of BS5550 has been prepared under the directi
8、on of the Cinematography and Photography Standards Committee. It is identical with ISO7831:1986 “Cinematography A-chain frequency response for reproduction of35mm photographic sound Reproduction characteristics”, published by the International Organization for Standardization (ISO). Terminology and
9、conventions. The text of the International Standard has been approved as suitable for publication as a British Standard without deviation. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn especially to the following. The comma has be
10、en used as a decimal marker. In British Standards it is current practice to use a full point on the baseline as the decimal marker. Wherever the words “International Standard” appear, referring to this standard, they should be read as “Subsection of BS5550”. A British Standard does not purport to in
11、clude all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Cross-references International Standard Corresponding British Standard BS 5550 Cin
12、ematography ISO 2969:1977 Subsection 7.4.1:1978 Specification and measurements for the electro-acoustic response of motion-picture control rooms and indoor theatres (Identical) ISO 6025:1982 Subsection 5.4.2:1983 Specification for photographic-monophonic sound test films (Identical) Summary of pages
13、 This document comprises a front cover, an inside front cover, pagesi andii, pages1 to4, an inside back cover and a back cover. This 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.BS5550
14、-3.4.9:1987 BSI 10-1999 1 1 Scope and field of application This International Standard specifies the A-chain electrical frequency response characteristic for photographic sound reproduction in motion-picture control rooms and indoor theatres. It is intended, in conjunction with ISO 2969, to assist i
15、n the standardization of recording monitor and reproduction characteristics of motion-picture sound dubbing theatres, review rooms and indoor theatres. This International Standard covers that part of the motion-picture sound system from the transducer to the input terminals of the main fader. 2 Refe
16、rences ISO 2969, Cinematography Electro-acoustic response of motion-picture control rooms and indoor theatres Specifications and measurements. ISO 6025, Cinematography Photographic-monophonic sound test films Specifications. 3 Definitions For the purpose of this International Standard, the following
17、 definitions apply. 3.1 complete sound reproduction system a system used (seeFigure 1) in sound dubbing theatres, review rooms and indoor theatres; by convention consists of an “A-chain and a B-chain” 3.2 type 1 sound track (also known as an academy sound track) a conventional pre-emphasized photogr
18、aphic sound track, which is intended for replay over conventionally de-emphasized theatre playback systems 3.3 type 2 sound track this equalization in recording and reproduction is only applied to some magnetic tracks and is outside the scope of this International Standard 3.4 type 3 sound track a p
19、hotographic sound track which has been pre-emphasized and is intended for replay over a theatre loudspeaker system aligned to Curve X of ISO2969 NOTEA type 3 sound track will normally require decoding with an electronic noise reduction system decoder. 3.5 A-chain (transducer system) the “A” part of
20、a motion-picture sound system (seeFigure 1), which extends from the transducer to the input terminals of the main fader NOTEIt is customary for the A-chain to contain the necessary de-emphasis network for the replay of type1 sound tracks. In some theatres part of the de-emphasis characteristic may r
21、esult from aperture loss. Type3 sound tracks do not require use of a de-emphasis network and aperture loss will normally require the use of noise reduction decoding circuitry. 3.6 B-chain (final chain) the “B” part of a motion-picture reproduction system (seeFigure 1), which extends from the input t
22、erminals of the main fader to the listening area of the room or auditorium NOTETwo B-chain characteristics are described in ISO2969, identified as curves N and X. 4 Method of measurement The electrical response shall be measured across the fader input terminals or at an equivalent position, using a
23、high impedance voltmeter accurate from20Hz to20kHz1dB. 5 Characteristics When a multi-frequency photographic test film, conforming to ISO6025, is played on the reproducer, the measured frequency response characteristic shall be within the tolerances of the curves given inTable 1 and Table 2. 5.1 Col
24、umn two ofTable 1 represents current practice for the replay of type1 sound tracks over curve NB-chain. 5.2 Column three ofTable 1 represents current practice for the replay of type1 sound tracks over a curve XB-chain. 5.3 Column four ofTable 1 represents current practice for the replay of type3 sou
25、nd tracks over a curve XB-chain. NOTEIn some theatres, it may not be possible to separate the overall A + B responses. For reference purposes, therefore, Table 2 andFigure 3 show the total “A + B” responses.BS5550-3.4.9:1987 2 BSI 10-1999 Table 1 A-chain frequency response for reproduction of35mmpho
26、tographic sound Frequency Type 1 sound track Type 3 sound track for use with curve Tolerances For use with curve N B-chain for use with curve X B-chain X B-chain Hz dB dB dB dB 40 63 0 0 0 0 0 0 2 125 250 500 0 0 0 0 0 0 0 0 0 1 1 000 2 000 2 500 0 1,0 2,0 0 1,0 2,0 0 0 0 3 150 4 000 5 000 3,0 4,0 5
27、,0 3,0 4,5 6,5 0 0 0 6 300 7 100 8 000 6,0 7,0 7,5 9,0 10,5 12,0 0 0 0 9 000 10 000 8,0 9,0 14,0 16,0 0 0 Figure 1 Complete sound reproducing systemBS5550-3.4.9:1987 BSI 10-1999 3 Figure 2 A-chain characteristics for type 1 photographic sound tracksBS5550-3.4.9:1987 4 BSI 10-1999 Annex A Overall A +
28、 B response for the replay of type 1 and type 3 photographic sound track (This annex does not form a part of the standard.) A.1 For reference purposes only,Table 2 andFigure 3 show the overall A+B response for the replay of type1 and type3 photographic sound-track. NOTEThe B-chain contribution to th
29、e overall A + B response is derived from the measurement techniques described in ISO2969. Table 2 Overall A + B response A.2 The figures inTable 2 (column two) and Figure 3 (solid curve) represent the average of150 theatre replay curves measured in six countries between1971 and1975, adjusted slightl
30、y to take account of current international practice. This curve is intended to ensure satisfactory replay of typically pre-emphasized sound tracks. Frequency Type 1 sound track Type 3 sound track Hz dB dB 40 63 125 8,0 3,0 0 2,0 0 0 250 500 1 000 0 0 0 0 0 0 2 000 2 500 3 150 1,0 3,0 5,0 0 1,0 2,0 4
31、 000 5 000 6 300 7,5 10,5 14,0 3,0 4,0 5,0 7 100 8 000 16,0 18,0 5,5 6,0 9 000 10 000 20,5 23,0 6,5 7,0 Figure 3 Overall A + B responseBS5550-3.4.9:1987 BSI 10-1999 Publications referred to See national foreword.BS 5550-3.4.9: 1987 ISO7831:1986 BSI 389 Chiswick High Road London W4 4AL BSIBritishStan
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