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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 Connector Layout .......................................................... 3-2

3.4

Preview Theatre ....................................................................................... 3-2

3.4.1

Concept ........................................................................................ 3-2

3.4.2

Installation.................................................................................... 3-2

3.4.3

Alignment .................................................................................... 3-3

3.5

Dubbing studio......................................................................................... 3-4

Chapter 4

Specifications

.......................................................................................... 4-1

Appendix A Background

............................................................................................. A-1

A.1 Loudness ................................................................................................. A-1

A.2 How Loud Is a Movie? ........................................................................... A-3

A.3 Standardizing a Measurement Technique for Soundtrack “Loudness” .. A-4

A.4 Analysis of the Data................................................................................ A-6

MAIN

Summary of Contents for 737

Page 1: ...Dolby Model 737 Soundtrack Loudness Meter Leq m Users Manual Issue 3 Part No 91533 MAIN ...

Page 2: ...ms implied by statute are excluded to the fullest extent allowed by law LIMITATION OF LIABILITY It is understood and agreed that Dolby Laboratories liability whether in contract in tort under any warranty in negligence or otherwise shall not exceed the cost of repair or replacement of the defective components and under no circumstances shall Dolby Laboratories be liable for incidental special dire...

Page 3: ...Inputs 2 3 2 2 2 Mon Out 2 4 2 2 3 DC Out 2 4 2 2 4 Power and Control 2 5 2 3 Connection and Calibration 2 5 2 3 1 Connecting to an Audio Console 2 5 2 3 2 Connecting to a Dolby Cinema Processor 2 6 2 3 3 Connecting to a DA10 20 Digital Adapter 2 6 2 3 4 Connecting to Non Dolby Digital Adapters 2 7 2 3 5 Connecting to the SDU4 Surround Decoder 2 7 2 3 6 Calibration Procedure 2 7 2 3 7 Automated In...

Page 4: ...yout 3 2 3 4 Preview Theatre 3 2 3 4 1 Concept 3 2 3 4 2 Installation 3 2 3 4 3 Alignment 3 3 3 5 Dubbing studio 3 4 Chapter 4 Specifications 4 1 Appendix A Background A 1 A 1 Loudness A 1 A 2 How Loud Is a Movie A 3 A 3 Standardizing a Measurement Technique for Soundtrack Loudness A 4 A 4 Analysis of the Data A 6 MAIN ...

Page 5: ... 3 2 Installation of Cat No 448B 3 2 3 3 Typical UK setup 3 4 3 4 Cat No 448B Interface Adapter schematic 3 7 A 1 Peak levels of photographic soundtrack formats A 2 A 2 A weighting vs CCIR weighting curve offset by 5 6 dB A 5 A 3 CCIR weighting Leq m shows influence of 2 6 kHz region A 6 A 4 Comparison of weighted and un weighted Leq A 7 A 5 Comparison of Leq m and peak levels A 8 A 6 Peak levels ...

Page 6: ...2 4 2 4 Power and control connector wiring convention 2 5 2 5 DA10 20 Audio Out Conn J8 Signal Assignments 2 6 2 6 Calibration levels for Dolby Dolby SR and Dolby Digital soundtracks 2 7 3 1 Logic map of Cat No 448B 3 1 3 2 Connecting the Cat No 448B to the CP65 and CP55 3 3 3 3 Pin convention 3 3 3 4 Pin convention continued 3 3 MAIN ...

Page 7: ...ginning and end of an entire movie The degree of repeatability of Model 737 measurements is dependent on the length of the measure ment For example a ten second spot requires about two frame accuracy whereas a two minute thirty second trailer needs only two second accuracy for correct measure ment For an entire feature the measurement can be started and stopped at a convenient time within two minu...

Page 8: ...r moving coil meter for trend analysis The Trip Set adjustment sets the level that lights the Trip LED and triggers a signal to the Trip Output The Trip Output can activate a more noticeable device such as a light or sound to alert the user that a preset level has been exceeded at the end of the measurement 2 1 Front Panel Controls The front panel has three pushbuttons Cal Start Stop a two digit L...

Page 9: ...position switch that sets a value from 78 Leq m at position 0 to 92 Leq m at position E in 1 unit increments When Stop is pressed to end the measurement if the Trip Set level has been exceeded the Trip LED lights and a signal is sent to Trip Out The Trip LED does not light during the measurement to allow transient Leq m values to exceed the Trip Set value without triggering Trip Out Note The Trip ...

Page 10: ...t when measuring 5 1 channel material Figure 2 4 Audio input connectors detail of rear panel The XLR input connectors for channels 1 6 use the following wiring convention Table 2 1 XLR input wiring convention for channels 1 6 Pin Connection 1 Chassis 2 Audio 3 Audio Ch 1 Lt Left Dolby and the double D symbol are trademarks of Dolby Laboratories Ch 3 Rt Right Ch 2 Center Ch 4 Left Surround Ch 5 Rig...

Page 11: ...e balanced with the studio monitor level Mon Out uses the following wiring convention Table 2 2 Mon Out wiring convention 2 2 3 DC Out DC Out is an unbalanced output to drive an optional moving coil meter chart recorder Using a 1 mA moving coil meter with a calibrating potentiometer across its terminals is a useful method to observe measurement trends DC Out uses the following wiring convention Ta...

Page 12: ...are independent of the signal source Dolby Level should be used as the test signal input level In the digital domain Dolby Level correlates to 20 dBFS 20 dB below Full Scale digital The calibration for each input must be performed with only that input connected When that input is calibrated unplug it and plug in the next input to calibrate All inputs are connected after the calibration in preparat...

Page 13: ...mono will result in incorrect levels 2 3 3 Connecting to a DA10 20 Digital Adapter When checking levels in a theatre or print checking facility the Model 737 derives its input signals directly from the J8 connectors on the back of the DA10 20 The following table lists the CP Audio Out Conn J8 pin number signal assignments and the nearest ground pin Table 2 5 DA10 20 Audio Out Conn J8 Signal Assign...

Page 14: ... input trimpots must be used to calibrate the inputs to standard levels to account for the differing levels and formats of the various signal sources Use the table below to determine the calibration setting and follow the steps below to calibrate the inputs Table 2 6 Calibration levels for Dolby Dolby SR and Dolby Digital soundtracks 1 Press the Cal button 2 Send the appropriate test signal at Dol...

Page 15: ...ck plug in all inputs and send the appropriate tone to all applicable channels The meter should register an Leq m value of 88 Dolby Lt Rt 91 Dolby Digital Dolby SR Lt Rt and Dolby LCRS soundtracks 94 Dolby SR LCRS 6 Repeat the calibration if there is a significant discrepancy Note The 3 dB difference between L C R and the surround channels matches the transfer levels for Dolby Digital movie soundt...

Page 16: ...do not use it Consult a qualified electrician 2 5 Interface The connections for remote start stop control are normally wired to a relay across the projector motor or to a console mounted toggle switch When the contacts close or the Stop button is pressed the display flashes the last measured value When the contacts open again or the Start button is pressed the unit enters measurement mode Pressing...

Page 17: ... and make up gain stages The signals on the wipers of the selector switch controlled by the Mon trimpot are buffered and sent to Mon Out on the rear panel CCIR Filter Rectifier X 2 in in in in in in in in in in in in L Lt C Ls R Rt Sub Rs Monitor Out Hold Cal Run Start Average Trip Level 7 3 Trip point out DC out fine level Rectifier and LED Driver Remote Start Stop CCIR Filter CCIR Filter CCIR Fi...

Page 18: ...short term average DC voltage is converted to12 bit binary and sent to a 6805 processor that also averages but over a much longer time span The samples are taken at 850 msec intervals summed divided by the time since the Start button was pressed and then converted to a square root value This value is then converted to a dB log scale scaled to a reference level of 85 and sent to the front panel LED...

Page 19: ...t is appropriate for most studio applications assuming that Lt Rt exist on monitor buses 2 3 or 1 3 Input jumpers are available to switch between the two The Cat No 448B can switch an auxiliary two track input i e Optical from Cat No 150 to the Model 737 and pass this auxiliary signal to the DS4 E UK auxiliary meter input normalized for Dolby Level This increases the versatility of the board to co...

Page 20: ...six track input to ensure sufficient gain 3 4 2 Installation Figure 3 2 Installation of Cat No 448B 1 Before mounting the Cat No 448B ensure the jumpers LK1 4 are in the upper 1 3 position 2 Connect the Cat No 448B with the cinema processor using Table 3 2 and adhere to the pin conventions in Table 3 3 and Table 3 4 Lt Rt GND Lt Rt OPT MAT SR 15 15 0V CAT150 TO DS4E L L C C R R Ls Ls Rs Rs Sw Sw F...

Page 21: ... a null point at 85 dB L C R Sw and 82 dB Ls Rs for each channel 2 Thread up and play a length of Cat No 69T with the cinema processor in Format 01 Mono and check that the calibration of the optical pre amp card is normal 3 Select Format 04 Dolby Stereo Connect each channel to the Model 737 in turn L R and adjust RV1 L and RV2 R trim pots of the Cat No 448B to obtain a null point at 85 dB for each...

Page 22: ...via the auxiliary input OPT and MAT should be fed from either the FA line of the CP65 or the MAT line of the dubbing interface and SR should be grounded Follow the installation steps in Section 3 4 2 on page 2 The six track input is paralleled from the 300 mV input to the CP65 after any switching between the monitor bus and DA20 Figure 3 3 Typical UK setup Example 2 The six track main inputs are b...

Page 23: ...K1 4 in the upper position 4 Make the following connections before mounting the Cat No 448B see Table 3 3 and Table 3 4 for pin conventions 5 Mount the Cat No 448B to the CP65 back panel using the spacers provided and then make the following connections 6 Connect the Cat No 448B output to the Model 737 7 Mount the dubbing interface Cat No 448 on top of the Cat No 448B Cat No 448B CP65 CP55 From Ca...

Page 24: ...tary switch on the Cat No 291 of the DS4 E is set to Lt Rt position 5 Send tone at Dolby Level to Lt Rt 6 dB on DS4 E meter and check Model 737 for 85 per channel 6 Select SR on the DS4 E SR A or Proc 2 switch illuminated and check Model 737 for 88 per channel 7 Place the DS4 E meter to Monitor position rear toggle switch in down position and adjust the rear trim pots on the meter for 6 dB per cha...

Page 25: ...Model 737 Soundtrack Loudness Meter Leq m Cat No 448B Input Adapter Board 3 7 Figure 3 4 Cat No 448B Interface Adapter Schematic MAIN ...

Page 26: ...n Operating Storage 0o C to 70o C Humidity Up to 90 relative humidity non condensing EMC Limits AC power line conducted Per EN 55022 Radiated Per EN 55022 Immunity Per EN 50082 1 General Dimensions 19 x 7 8 x 1 75 inches 43 x 20 x 4 5 cm Net Weight 6 lb 3 kg Power Requirements 24 VAC 500 mA wall transformer provided Power Consumption 10 WAC max MAIN ...

Page 27: ... be surprised at the subjective statement that The Right Stuff 1983 Dolby A type 70 mm and Dolby A type stereo optical was a loud movie The Right Stuff was a subjectively louder movie than Shine 1996 Dolby Digital Since Shine was subjectively louder than Days of Heaven 1978 perhaps a case could be made that movies have been getting both louder and quieter Of course this does not lead to an objecti...

Page 28: ... known as associative loudness When the dubbing mixer sees an actor on the screen and there is no fight with music or effects the dialogue level in a moderate close up is set to be plausible for the visual Within reasonable limits this holds true to within 2 or 3 dB This natural dialogue level does not hold true for narration as there is no corresponding visual reference Music and effects have no ...

Page 29: ...s has led to the desire for a uniform measurement technique and a self disciplined constraint It is possible that the increased use of headroom from Dolby A type to Dolby SR and digital releases has not been matched by a corresponding increase in power amplifier and loudspeaker capability The resultant distortion from overloaded equipment may well exacerbate the loudness problems of recent soundtr...

Page 30: ...e of sustained loudness is called Leq loudness equivalent which was originally derived to gauge potential hearing damage from exposure in industrial environments to sustained varying level sounds Leq can be defined as the level of a steady state tone with an equivalent level as the level of a time variant signal The original intent was to define potential hearing damage in industrial noise environ...

Page 31: ...he subjective annoyance criteria Figure A 2 Figure A 2 A weighting vs CCIR weighting curve offset by 5 6 dB Although there is no technical parallel between high level soundtrack loudness and low level recording medium noise the CCIR curve provided a convenient weighting filter for the tests and a better subjective match than Leq a The CCIR curve can be further adapted to represent soundtrack loudn...

Page 32: ...g lines denotes the amount of bass content in the program Lines with higher slopes indicate larger amounts of bass while horizontal lines 0 slope or lines with negative slope indicate less bass content Of the samples shown notice that Indiana Jones and the Temple of Doom is raised in the hierarchy due to the lack of bass in the five minute sample This matches the apparent loudness of the sample on...

Page 33: ... comparison of dialogue levels of Spencer s Mountain 1963 an Academy mono film with the dialogue level of Shine 1996 a Dolby Digital release The two films show identical Leq levels confirming the supposition that mixers set dialogue levels at a plausible point associative loudness regardless of the format of the release Shine Reel 5 D Gakkou No Kaidan A Empire Trailer D Twister Trailer D Prisoners...

Page 34: ...Shine Reel 5 D Gakkou No Kaidan A Em pire Trailer D Twister Trailer D Prisoners of the M ountain Trailer D M ars Attacks Trailer D Slayer s Return SR Star Wars Trailer D Shine Trailer D ST Generations Reel 2 D Evita Trailer D Indie Tem ple of Doom A Spencer s Mountain M ono Shine Dialog D Leqm CCIR weighted Peak Level C weighted fast 5 6 dB offset Tim e dB 75 80 85 90 95 100 105 Shine demo 1 Rach ...

Page 35: ...his constraint however would have the effect of restricting dynamic range and not necessarily of controlling the subjective loudness of the material US created digital trailers typically have an Leq m level up to 15 or even 20 dB above the feature they advertise It must be emphasized however that the higher Leq m values of trailers is caused in part by the selection of only the loudest most exciti...

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