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"Manual of Analoque Sound Restoration Techniques"

von Peter Copeland. - Dieses (elektronische) Buch ist von der "British Library" public gestellt worden und somit frei verfügabr. Ich hatte dort in London im Feb. 2009 angerufen und mit dem Archiv-Leiter gesprochen.

This manual is dedicated to the memory of Patrick Saul who founded the British Institute of Recorded Sound (renamed the British Library Sound Archive in 1983) and was its director from 1953 to 1978, thereby setting the scene which made this manual possible.

Selbstverständlich kommt hier der vollständige Verweis auf die Quellen:
Published September 2008 by The British Library, 96 Euston Road, London NW1 2DB Copyright 2008, The British Library Board www.bl.uk.

CONTENTS (Achtung: hier ist das Original-Inhaltsverzeichnis)

(Der Verweis auf die Seitennummern stimmt natürlich nicht mehr.)
Preface and Acknowledgements (kommen bei uns ganz hinten)

1 Introduction/Einführung (ist bei uns Teil 1)

1.1 The organisation of this manual............3
1.2 The target audience for this manual......4
1.3 The original sound.................................6
1.4 Operational principles...........................8
1.5 A quadruple conservation strategy......10
1.6 How to achieve objectivity...................11
1.7 The necessity for documentation.........12

2 The overall copying strategy (ist bei uns Teil 2)

2.1 The problem to be solved..........................13
2.2 General issues.......................................13
2.3 The principle of the “Power-Bandwidth Product”.......14
2.4 Restricting the bandwidth.........................16
2.5 Deciding priorities......................................17
2.6 Getting the best original power-bandwidth product.....17
2.7 Archive, objective, and service copies......19
2.8 “Partially objective” copies.........................20
2.9 Documentation strategy..........................20
2.10 Absolute phase........................................22
2.11 Relative phase...........................................23
2.12 Scale distortion..........................................23
2.13 Conclusion.................................................24

3 Digital conversion of analogue sound (ist bei uns Teil 3)

3.1 The advantages of digital audio.............................................25
3.2 Technical restrictions of digital audio - the “power” element....26
3.3 Technical limitations of digital audio: the “bandwidth” element.28
3.4 Operational techniques for digital encoding...............................30
3.5 Difficulties of “cloning” digital recordings.................................30
3.6 Digital data compression.......................................................33
3.7 A severe warning...................................................................35
3.8 Digital watermarking and copy protection..............................37
3.9 The use of general-purpose computers..................................38
3.10 Processes better handled in the analogue domain...............39
3.11 Digital recording media...........................................................40

4 Grooves and styli (ist bei uns Teil 4)

4.1 Introduction............................................42
4.2 Basic turntable principles.........................43
4.3 Pickups and other devices........................44
4.4 Conventional electrical pickup considerations...45
4.5 Operational procedure for selecting a stylus....47
4.6 U-shaped and V-shaped grooves.............48
4.7 The principle of minimising groove hiss.....52
4.8 “Soft” replay styli..................................53
4.9 “Hard” replay styli.............................55
4.10 Stereo techniques.......................57
4.11 “Elliptical” and other styli........59
4.12 Other considerations..............61
4.13 Playing records backwards......63
4.14 Half-speed copying.................65
4.15 Distortion correction...............65
4.16 Radius compensation.............67
4.17 Electronic click reduction.........70
4.18 Electronic hiss reduction..........74
4.19 Eliminating rumble....................76
4.20 De-thumping............................76
4.21 Future developments.................77
4.22 Recommendations and conclusion....78

5 Speed setting (ist bei uns Teil 5)

5.1 Introduction...........................................................81
5.2 History of speed control.........................................82
5.3 History of speed-control in visual media..................84
5.4 Setting the speed of old commercial sound records...86
5.5 Musical considerations............................................90
5.6 Strengths and weaknesses of “standard pitch”......91
5.7 Non-“standard” pitches..........................................91
5.8 The use of vocal quality..........................................92
5.9 Variable-speed recordings.....................................93
5.10 Engineering evidence..........................................95
5.11 Timings................................................................97

6 Frequency responses of grooved media

6.1 The problem stated
6.2 A broad history of equalisation
6.3 Why previous writers have gone wrong
6.4 Two ways to define “a flat frequency response”
6.5 Equalisation ethics and philosophy
6.6 Old frequency records as evidence of characteristics
6.7 Two common characteristics
6.8 Practical limits to equalisation
6.9 Practical test discs
6.10 International standard microgroove test discs
6.11 Coarsegroove (78rpm) test discs
6.12 Generalised study of electromagnetic cutters
6.13 Characteristics of “simple” cutterheads
6.14 High-resistance cutterheads
6.15 Western Electric, and similar line-damped recording systems
6.16 Western Electric revolutionises sound recording
6.17 The Western Electric microphone
6.18 The Western Electric amplifier
6.19 Documentation of HMV amplifier settings, 1925-1931
6.20 The Western Electric cutterhead
6.21 How to recognise recordings made with Western Electric 1A and 1B systems
6.22 Summary of equalisation techniques for the above
6.23 Western Electric developments after 1931
6.24 Recognising recordings made on RCA-modified and Western Electric 1C and 1D systems
6.25 Summary of equalisation techniques for the above
6.26 Other systems using line-damped cutterheads: British Brunswick, Decca, DGG 1925-1939
6.27 Other systems using line-damped cutterheads: The Lindström system
6.28 Conclusion to line-damped systems
6.29 The Blumlein system
6.30 The Blumlein microphone
6.31 The Blumlein moving-coil cutterhead
6.32 Test discs made by Blumlein’s system
6.33 How to recognise Blumlein cutters on commercial records, 1931-1944
6.34 Summary of how to equalise the above
6.35 The Gramophone Company system
6.36 How to recognise the Gramophone Company system on commercial records..131
6.37 Summary of how to equalise “Gramophone system” recordings.................131
6.38 Extended-Range Blumlein recordings (1943-5) and later systems...............131
6.39 Summary of how to equalise “Extended-Range” and subsequent systems....132
6.40 Early EMI long-playing and 45 r.p.m. records
6.41 Other systems giving a “Blumlein-shaped” curve - amateur and semi-pro machines
6.42 British Decca-group recordings 1935-1944
6.43 Summary of how to equalise Decca-group recordings 1935-1944
6.44 Synchrophone
6.45 Summary of how to equalise Synchrophone recordings....................135
6.46 Conclusion to “Blumlein-shaped” equalisation..................135
6.47 The Marconi system..............................................136
6.48 BBC Disc Record equalisation - Introduction..137
6.49 The subject matter of these sections..............138
6.50 Pre-history of BBC disc recording..................139
6.51 BBC matrix numbers......................................139
6.52 BBC “current library” numbers......................140
6.53 BBC M.S.S. recordings...................................141
6.54 BBC American equipment..............................142
6.55 BBC transportable equipment........................142
6.56 BBC coarsegroove 33rpm discs......................142
6.57 Later BBC coarsegroove systems...................143
6.58 Early BBC microgroove discs..........................145
6.59 BBC “CCIR characteristics”...........................145
6.60 RIAA and subsequently.................................146
6.61 Brief summary of BBC characteristics.............146
6.62 “Standard” equalisation curves.....................147
6.63 General history of “standards”......................147
6.64 Defining standard curves...............................149
6.65 Discographical problems................................150
6.66 General history of changeover procedures....151
6.67 NAB (later “NARTB”) characteristics.............152
6.68 Decca Group (UK) “ffrr” characteristics........152
6.69 American Columbia LPs.................................155
6.70 “AES” characteristics....................................156
6.71 Various RCA characteristics...........................157
6.72 “CCIR” characteristics..................................158
6.73 “DIN” characteristics....................................158
6.74 Concluding remarks......................................159

7 Analogue tape reproduction

7.1 Preliminary remarks...........................................163
7.2 Historical development of magnetic sound recording...164
7.3 Bias...................................................................166
7.4 Magnetised tape heads......................................168
7.5 Print-through....................................................169
7.6 Azimuth............................................................170
7.7 Frequency responses of tape recordings.............172
7.8 “Standard” characteristics on open-reel tapes....173
7.9 Standards on tape cassettes................................176
7.10 Operational principles...................................177
7.11 “Mono” and “half-track” tapes....................180
7.12 “Twin-track” tapes.......................................181
7.13 “Quarter-track” tapes...................................182
7.14 Practical reproduction issues..........................183
7.15 “Hi-fi” Tracks on domestic video..................184

8 Optical film reproduction

8.1 Introduction......................................................187
8.2 Optical sound with moving pictures...................187
8.3 Considerations of strategy..................................188
8.4 Basic types of optical soundtracks.......................189
8.5 Soundtracks combined with optical picture media....190
8.6 Recovering the power-bandwidth product.........191
8.7 Frequency responses.........................................193
8.8 Reducing background noise...............................194

9 Reciprocal noise reduction

9.1 Principles of noise reduction...............................196
9.2 Non-reciprocal and reciprocal noise-reduction....196
9.3 Recognising reciprocal noise reduction systems..197
9.4 Principles of reciprocal noise reduction systems..198
9.5 Dolby “A”.........................................................199
9.6 Dolby “B”.........................................................201
9.7 DBX systems......................................................202
9.8 JVC ANRS (Audio Noise Reduction System).......205
9.9 Telcom C4.........................................................205
9.10 Telefunken “High-Com”...............................206
9.11 The “CX” systems.........................................206
9.12 Dolby “C”....................................................207
9.13 Dolby SR and Dolby S...................................208
9.14 Other noise reduction systems......................209
9.15 Noise reduction systems not needing treatment....211
9.16 Conclusion...................................................211

10 Spatial recordings

10.1 Introduction.................................................213
10.2 “Two-channel” recordings............................213
10.3 Archaeological stereo....................................216
10.4 Matrixing into two channels..........................218
10.5 Three-channel recordings..............................218
10.6 Four-channel recordings - in the cinema.......219
10.7 Four-channel audio-only principles................220
10.8 Matrix “quadraphonic” systems....................221
10.9 The QS system.................................................221
10.10 The SQ system..................................................222
10.11 Matrix H................................................................223
10.12 “Dolby Stereo”..........................................................224
10.13 Developments of “Dolby Stereo” - (a) Dolby AC-3..........226
10.14 Developments of “Dolby Stereo” - (b) Dolby headphone...227
10.15 Developments of “Dolby Stereo” - (c) Pro Logic 2..........227
10.16 Discrete 4-channel systems - The JVC CD-4 system....227
10.17 The “UD-4” system..................................................228
10.18 “Ambisonics”.........................................................229
10.19 Other discrete four-channel media.....................230
10.20 More than five-channel systems.......................230
10.21 Multitrack master-tapes................................231

11 Dynamics

11.1 Introduction.................................................233
11.2 The reasons for dynamic compression...........234
11.3 Acoustic recording........................................235
11.4 Manually-controlled electrical recording........235
11.5 Procedures for reversing manual control.......237
11.6 Automatic volume controlling.......................238
11.7 Principles of limiters and compressors............241
11.8 Identifying limited recordings........................243
11.9 Attack times.................................................244
11.10 Decay-times.................................................245
11.11 The compression-ratio and how to kludge It.246

12 Acoustic recordings

12.1 Introduction.................................................249
12.2 Ethical matters..............................................249
12.3 Overall view of acoustic recording hardware.251
12.4 Performance modifications............................252
12.5 Procedures for reverse-engineering the effects........254
12.6 Documentation of HMV acoustic recording equipment...255
12.7 The Recording horn - why horns were used...........256
12.8 The lack of bass with horn recording....................257
12.9 Resonances of air within the horn.................257
12.10 Experimental methodology............................257
12.11 Design of an Acoustic Horn Equaliser............259
12.12 Resonances of the horn itself.........................259
12.13 Positions of artists in relation to a conical horn....261
12.14 Acoustic impedances.....................................262
12.15 Joining two horns..........................................263
12.16 Joining three or more horns..........................264
12.17 Another way of connecting several horns......264
12.18 Electrical equalisation of recordings made with parallel-sided tubes....265
12.19 Electrical equalisation of recordings made with multiple recording horns....266
12.20 The recording soundbox................................267
12.21 “Lumped” and “distributed” components....267
12.22 How pre-1925 soundboxes worked..............268
12.23 Practicalities of acoustic recording diaphragms.......270
12.24 The rest of the soundbox..............................271
12.25 Notes on variations.......................................271
12.26 When we should apply these lessons............274
12.27 Summary of present-day equalisation possibilities......274
12.28 Conclusion...................................................275

13 The engineer and the artist

13.1 Introduction.................................................279
13.2 The effect of playing-time upon recorded performances.....279
13.3 The introduction of the microphone..............283
13.4 The performing environment........................284
13.5 “Multitrack” issues........................................287
13.6 Signal strengths............................................289
13.7 Frequency ranges..........................................290
13.8 Monitoring sound recordings........................291
13.9 The effects of playback.................................292
13.10 The Costs of recording, making copies, and playback....295
13.10.1 The dawn of sound recording.............295
13.10.2 Mass produced cylinders.....................297
13.10.3 Coarsegroove disc mastering costs......297
13.10.4 Retail prices of coarsegroove pressings298
13.10.5 One-off disc recording........................300
13.10.6 Magnetic tape costs............................301
13.10.7 Pre-recorded tapes and cassettes........302
13.10.8 Popular music
13.10.9 Digital formats
13.10.10 Conclusion for pure sound recordings
13.11 The cinema and the performer
13.12 Film sound on disc
13.13 The art of film sound
13.14 Film sound editing and dubbing
13.15 The automatic volume limiter
13.16 Films, video, and the acoustic environment
13.17 Making continuous performances
13.18 Audio monitoring for visual media
13.19 Listening conditions and the target audience and its equipment
13.20 The influence of naturalism

Appendix 1. Preparing media for playback
Appendix 2: Aligning analogue tape reproducers...............328
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