Dolby Laboratories 737 manuale d’uso

Dolby Model 737 Soundtr ack Loudness Meter – Leq(m) Users’ Ma nual Is s ue 3 P art N o . 9 1 533 MAIN[...]

Dolby Laboratories Inc www.dolby.com United Stat es 100 Potrero Avenue San Francisco, CA 94103-4813 Telephone 415-558-0200 Facsimile 415-863-1373 United Kingdom Wootton Bassett Wiltshire SN4 8QJ Engl and Telephone (44) 1793-842100 Facsimile (44) 1793-842101 WARNING: Troubleshooting must be performed by trained technicians. Do not at t e m pt to ser[...]

iii Table o f Conten ts List of Figures ......................................................................................................................... v List of Tables ..........................................................................................................................vi Chapter 1 Introduction .......................[...]

iv Chapter 3 Cat. No. 448B Input Adapter Board .............................................. 3-1 3.1 Introduction.............................................................................................. 3-1 3.2 Logic map ................................................................................................ 3-1 3.3 Component and Conn[...]

v List of Fig ures 2-1 Model 737 front panel .................................................................................................... 2- 1 2-2 Detail of front panel controls .......................................................................................... 2-1 2-3 Model 737 back panel ............................................[...]

vi List of Tab les 2-1 XLR input wiring convention for channels 1-6 ............................................................. 2-3 2-2 Mon Out wiring convention ........................................................................................... 2-4 2-3 DC Out wiring convention .............................................................[...]

Model 737 Sound track Loudn ess Mete r - Leq( m) 1-1 Chapter 1 Introduction Leq(m) is a term used by Dolby Laboratories to desc ribe the level of annoyance in mov- ie soundtracks. The Leq(m) value is a weighted true ave rage of the audio power level s en t t o t h e camera in optical or digital soundtracks, or the same weighted true ave rage of the[...]

Model 737 Sound track Loudn ess Mete r - Leq( m) 2-1 Chapter 2 Operation and Features The Model 737 Soundtrack Loudness Meter – Leq(m) is a simple 1U, rack-mountable device that measures the equivalent loudness of one-, two-, four-, or six-channel inputs, typically from the non-equalized outputs of a cinema processor or mixing console. Since the [...]

Model 737 Sound track Loudn ess Meter - Leq( m) Opera tion and F eatures 2-2 2.1.1 6/4 – 2 Channel Swit ch Located to the left of the i nput trimpots (see Figure 2-2), this swi tch may be used in future versions to introduce a f ixed offset in the measur ement of two-channel encode d material. Presently ( version 1), the of fse t is set to zer o [...]

Model 737 Sound track Loudn ess Meter - Leq( m) Opera tion and F eatures 2-3 2.2 Back Panel Connectors The back panel has six audio input connectors (shown in detail in Figure 2-4), two output connector s, and a power/ control s ignal conne ctor (shown in de tail in Figur e 2-5). Figure 2-3 Model 737 ba ck panel 2.2.1 Analo g Audio Inputs Although [...]

Model 737 Sound track Loudn ess Meter - Leq( m) Opera tion and F eatures 2-4 2.2.2 Mon Out Figure 2-5 Mon and DC Out, and power/co ntrol conne ctor Mon Out is an unbala nced output which, in calibration mode, provides an unweighted mono mix of channels. I n measurement mode, Mon Out carries a mono mix of the outputs of the weighting filters. Liste [...]

Model 737 Sound track Loudn ess Meter - Leq( m) Opera tion and F eatures 2-5 2.2.4 Power and Control The 8-pin power and control connector uses the following wiring conventions for the control and AC power signals: Table 2-4 Power and c ontrol connec tor wirin g conven tion The trip output is a si mple open collec tor buffer that passes c urrent wh[...]

Model 737 Sound track Loudn ess Meter - Leq( m) Opera tion and F eatures 2-6 2.3.2 Connecting to a Dolby Cinema Processor The method for connecting a Dolby cinema processor with the Model 737 depends on the application. For a cinema processor used in a studio or dubbing stage, the matrix- encoded Lt and Rt signals are found on the Cat. No. 150E car[...]

Model 737 Sound track Loudn ess Meter - Leq( m) Opera tion and F eatures 2-7 2.3.4 Conn ecting to Non-Dolby Digital Adapters With the digital adapter connected to the Dolby cinema proc essor, make a parallel con- nection from the cinema processor to the a udio inputs on the Model 737, and use the test media from that manufacturer as the signal sour[...]

Model 737 Sound track Loudn ess Meter - Leq( m) Opera tion and F eatures 2-8 Notes: The null circuit has two points of transition (at 82 and 85), so the + and - LEDs should be used in conjunction with the numerica l display to set the correct levels for that input. Since the null points are only at 82 and 85, to align to 88, reduce the test tone le[...]

Model 737 Sound track Loudn ess Meter - Leq( m) Opera tion and F eatures 2-9 2.4 Mains Power The Model 737 uses a mains transformer that converts incoming AC to 24 VAC. The tra ns for me r has 1 mete r leads and should be placed at the base of the equipment rack in which t he uni t is m ounted. T h e t ra n sf o rm e r should not be opera ted with [...]

Model 737 Sound track Loudn ess Meter - Leq( m) Opera tion and F eatures 2-10 2.6 Block diagram Figure 2-6 Model 73 7 block diagram The six input channels each have a balanced to unbala nced stage buffering the input sig- na l. Tri mpo ts on the front panel set each channel ’ s input leve l. The unbalanced signals then pass to the metering CCIR f[...]

Model 737 Sound track Loudn ess Meter - Leq( m) Opera tion and F eatures 2-11 The selection switches are followed by five ide al rectifiers and squaring circuits. The five squared signals are added and short term averaged. The resultant varying DC signal passes to an analog long-term averaging circuit. This requires a logic signal fr om the pushbut[...]

Model 737 Sound track Loudn ess Mete r - Leq( m) 3-1 Chapter 3 Cat. No. 448B I nput Adapter Board 3.1 Introduction The Cat. No. 448B is an input adapter board that mounts to the rear of a CP65. The card will suitably switch and adapt signals from a two- or six-track source following logic c on- trol from the CP 65, CP55, or DS4-E (UK). Format calib[...]

Model 737 Sound track Loudn ess Mete r - Leq(m ) Cat. No. 448 B Inpu t Adapt er Board 3-2 3.3 Component and Connector Layout Figure 3-1 Cat. No. 448B In terface Ada pter 3.4 Preview The atre 3.4.1 Concept The DA10 or DA20 feeds six Dolby Digital channels; the Cat. No. 150 supplies two. Since the DA10/20 output is unbalanced, the positive tags shoul[...]

Model 737 Sound track Loudn ess Mete r - Leq(m ) Cat. No. 448 B Inpu t Adapt er Board 3-3 Table 3-2 Connec ting the C at. No. 448B to the CP65 and CP5 5 Table 3-3 Pin conv ention Table 3-4 Pin conv ention ( continue d) 3. Mount the Cat. No. 448-B to the CP65 back plane using the spacers provided. 4. Use Table 2-5 to c onnect the DA10/20 to the posi[...]

Model 737 Sound track Loudn ess Mete r - Leq(m ) Cat. No. 448 B Inpu t Adapt er Board 3-4 3.5 Dubbin g studio Dubbing Studio set-ups may vary depending upon location. Contact a Dolby sound consultant or Dolby office t o resolve any uncertainties. Installation of the Cat. No. 448B can be optimized using the logic map in Table 3-1 and Figure 3-4, the[...]

Model 737 Sound track Loudn ess Mete r - Leq(m ) Cat. No. 448 B Inpu t Adapt er Board 3-5 Follow these ste ps to install the de vices used in this e xample: 1. Isolate the mains power to the processor and remove the existing dubbing in- terf ace (Cat. No. 448); lea ve all connect ions to it in place. 2. Completely remove and discard the Cat. No. 44[...]

Model 737 Sound track Loudn ess Mete r - Leq(m ) Cat. No. 448 B Inpu t Adapt er Board 3-6 3.5.1 Al ignment 1. Set the DS4-E into Discrete mode (one green LED). 2. Send tone at Dolby Level to the studio monitor bus and align the Model 737 as described in Section 2.3.6 - Calibrat ion Procedure (Dolby Digital). Note: If LK1-4 ar e in the lower positio[...]

Mo d el 737 S o un d t r a c k L oud n e s s Met e r - L eq ( m ) C a t. N o . 44 8 B I np u t A d ap t er B o a r d 3-7 Figure 3-4 Cat. No. 448B In terface Ada pter Schema tic MAIN[...]

Model 737 Sound track Loudn ess Mete r - Leq( m) 4-1 Chapter 4 Specifications T e mperature and Humidity Operating 10 o C to 35 o C, natural convecti on cooling Non-Operati ng (Stora ge) 0 o C to 70 o C Humidity Up to 9 0% relati ve humidi ty , non-conden sing EMC Limits AC power line conducted Per EN 55022 Radiated Pe r EN 55022 Immunity Per EN 50[...]

Model 737 Sound track Loudn ess Mete r - Leq( m) A-1 Append ix A Back grou nd This Append ix is an ed ited version of a paper p ublished in the Januar y 1998 SM PTE Jo urnal (Volume 107, Numb er 1) ent itled “ Are Movies Too Loud ” by Io an Allen. The complete pa per is availab le from the Do lby website at www.dolby.c om/movies . Reprints of t[...]

Model 737 Sound track Loudn ess Mete r - Leq( m) Back ground A-2 This system worked quite well for many years. Dolby Stereo (A-type encoded) films had limited headroom and the resulting constrained dynamic range yielded few audience comp lai nts. Mo st th eatr es played films at the calibrate d level. Soundtrac k format tech- nology has been signif[...]

Model 737 Sound track Loudn ess Mete r - Leq( m) Back ground A-3 In practice, the following undesirable symptoms have arisen: • There are an i ncreasing number of audience complai nts that movies are t oo loud. Newspaper articles have been w ritten on the subject and respected sound mixers have spoken publicly about the problem. • Theatres are [...]

Model 737 Sound track Loudn ess Mete r - Leq( m) Back ground A-4 None of the existing criteria for loudness can be directly applied to a soundtrack. Fundamental l oudness is defined by the relationship between frequency and level. A re g u l a r V U o r PP M m e t er does not account for the ear ’ s varying sensiti vity with respect to frequency.[...]

Model 737 Sound track Loudn ess Mete r - Leq( m) Back ground A-5 A.3.1 Alternat ive Measureme nt Indices As might be expected, the samples yielded different loudness values when assessed with different systems. The low-frequency roll-off of A-weighting results in a reduction in Leq when the material has a substantial bass content. Determination of [...]

Model 737 Sound track Loudn ess Mete r - Leq( m) Back ground A-6 Figure A-3 CCIR-we ightin g (Leq(m) ) shows inf luence of 2 – 6 kHz region . A.4 Analysis of the Data Figure A-4 shows the relationship between un-weighted (Leq) and CCI R-weighted (Leq(m)) samples. The hierar chy on the right of the figure (un-weighted) differs from that on the lef[...]

Model 737 Sound track Loudn ess Mete r - Leq( m) Back ground A-7 Figure A-4 Com parison of weighted an d un-w eighted Le q. Figure A-5 compares the maximum peak level reached in ea ch sample wit h the weighted Leq(m) value. The slope of the line between the values is now proportional to the dynamic range : the range between the average level and th[...]

Model 737 Sound track Loudn ess Mete r - Leq( m) Back ground A-8 Fig ure A-5 Com parison of Leq(m ) and peak levels Figure A-6 Peak le vels in reel 4 of Shin e SR Cl i p A Cl i p Shine Re el 4 11 0 105 100 60 65 70 75 80 85 90 95 Shine Re el 5 (D) G akko u N o K ai da n ( A ) E m p ire T ra il e r (D ) Tw i s ter T ra il e r (D ) Pri so ner s of t [...]

Model 737 Sound track Loudn ess Mete r - Leq( m) Back ground A-9 Next, examine Figure A-5 again, then Figur e A-6, and compare the peak leve ls in reel 4 of Shine with the Leq. Although this reel has an extreme dynamic range, audienc es do not complain that it is too loud. In this case, the dynamic range is correct for the nature of the material, a[...]