Dolby Laboratories CP45 Installation And Alignment Manual
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Dolby Laboratories CP45 Installation And Alignment Manual

Dolby Laboratories CP45 Installation And Alignment Manual

Cinema processor
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The information contained in this Adobe Acrobat pdf
file is provided at your own risk and good judgment.
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exchange of information related to cinema
projection and film handling, with no warranties nor
obligations from the authors, for qualified field
service engineers.
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  • Page 1 Film-Tech The information contained in this Adobe Acrobat pdf file is provided at your own risk and good judgment. These manuals are designed to facilitate the exchange of information related to cinema projection and film handling, with no warranties nor obligations from the authors, for qualified field service engineers.
  • Page 2 Model CP45 Cinema Processor Installation and Alignment Manual Issue 2 Part No. 91389...
  • Page 3 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...

  • Page 4: Table Of Contents

    2.5 Mains Power Wiring....................2-10 2.6 Connect the Transformers to AC Mains Power............ 2-11 2.7 Hum Problems ......................2-11 2.8 CP45 Circuit Card Descriptions ................2-18 Cat. No. 510/514 Input/Output Card .............. 2-19 Cat. No. 511 Main Board ..................2-19 Cat.

  • Page 5: Table Of Contents

    5.6 Non-sync Level Adjustment ..................5-34 5.7 Final Check ........................5-36 SECTION 6 REFERENCE DIAGRAMS ...................... 6-1 CP45 Signal Path Block Diagram ..................6-2 CP45 Backplane Schematic ....................6-3 APPENDIX A EFFECT OF CHANGES IN SLIT HEIGHT ON SLIT LOSSES........A-1...
  • Page 6 A-type and SR releases. It has also been designed for convenient interface with theatre automation systems. Among the standard features of the CP45 are a built-in fader with remote and mute facilities; simple push-button soundtrack format selection; and comprehensive fail-safe features that include a built-in bypass system.
  • Page 7 Dolby noise reduction adjustments—and the B-chain alignment which covers the portions of the system from the room equalization circuits to the CP45 fader through to the loudspeakers. The alignment instructions in this Manual are presented in three columns. The first column, Action, contains a drawing of the item to be adjusted and a caption containing a brief description of the action to be taken.
  • Page 8 Surround equalizer provides bass, mid- two projectors with stereo solar cells frequency, and treble adjustments for left (available from Dolby Laboratories and right surround channels, mounted on brackets for most projector c) 50 or 100 Hz crossover for subwoofer types).

  • Page 9: Equipment Required

    • Voltmeter for measuring the exciter lamp power supply. • Test Films, available from Dolby Laboratories or equipment dealers. We recommend that you make loops of these test films, sufficiently long to go through the entire projector film path so that azimuth and lateral film position adjustments can be made accurately.
  • Page 10 3. 1kHz, 100% Modulation, Left/Right — Cat. No. 97 SMPTE Buzz Track Stereo Optical Surround Level — Cat. No. 151...
  • Page 11 1.85:1 widescreen or 2.35:1 anamorphic Sound formats: digital analog SR Dolby Laboratories Inc. • 100 Potrero Avenue San Francisco, CA 94103-4813 Telephone 415-558-0200 • Facsimile 415-863-1373 Dolby, the Double-D symbol and Dolby Stereo are trademarks of Dolby Laboratories Licensing Corporation S94/10117 7.

  • Page 12: Section 2 Initial Set-Up And Installation

    CP45 is being aligned. Replacing an Existing Sound System If the CP45 replaces an existing cinema sound system, play a typical film before you remove the old system so you will have a benchmark for...

  • Page 13: Disconnect The Old System

    Locate the power amplifiers away from the CP45 to avoid hum pickup problems. Always leave a 1U (43 mm, 1.75") space above and below the CP45 to provide adequate ventilation. Install an air guide or baffle to deflect hot air from equipment below the CP45.

  • Page 14: Remote Fader(S)

    If AUX/Non-sync 2 is used for background music, this is best wired to the surround input(s) so that it plays to the surround speakers in the auditorium to prevent the muffling effect of the curtains when these are closed. If the background music is stereo, then the feeds should be wired to the two AUX surround inputs.

  • Page 15: Jumpers And Switches

    Jumpers and Switches 2.4.1 Backplane Jumpers and Switches TEST M TEST M J9 J9 BOOTH MONITOR OUTPUT BOOTH MONITOR OUTPUT IN IN OUTPUT LEVEL RANGE OUTPUT LEVEL RANGE HIGH HIGH LEFT LEFT LEFT LEFT CENTER CENTER CENTER CENTER RIGHT RIGHT RIGHT RIGHT HEARING...

  • Page 16: Output Signal Test /Hearing Impaired Signal Select Switches

    TEST IMPAIRED IMPAIRED S S S S These switches select which CP45 output signal(s) are sent to connector J4 terminals 3 and 4. With HEARING IMPAIRED/TEST switch set to HEARING IMPAIRED: L, C, R, and S are combined for use with a hearing impaired system.
  • Page 17 2.4.3 Cat. No. 513 J501 J502 100Hz 1kHz 1.8kHz TREBLE 50Hz TREBLE FREQ FREQ 1kHz 1.8kHz TREBLE Subwoofer Jumpers Jumpers for controlling the subwoofer channel are located on the Cat. No. 513 equalization board. To gain access to these jumpers, open the front panel and remove the plate covering the equalization controls.
  • Page 18 Mono Surround Jumper This jumper should be installed for mono surround operation. If your cinema is equipped with separate power amplifiers and speaker wiring for left and right surround channels, an optional Cat.No.515 Stereo Surround board is available. This jumper is removed if the Cat.No.515 is installed. Note that stereo surround signals are only available in format 61, Aux.

  • Page 19: Cat. No. 510 Switches

    There is no center or subwoofer output. The CP45 is factory set to this position. MATRIX Selects full 2:4 matrix decoding of the non-sync signal.
  • Page 20 Power Input Switch This switch selects which type of mains transformer is used to power the CP45, AC output or DC output. AC is the factory setting. LED Soundhead amplifier type jumpers J1 and J2...

  • Page 21: Mains Power Wiring

    The CP45 is supplied with two mains powered transformers. One is used to power the unit during normal operation and the other is used when the CP45 is switched to BYPASS operation. If there is any chance that the source of power to the...

  • Page 22: Connect The Transformers To Ac Mains Power

    Hum Problems If you hear undesirable hum from the speakers when you apply power to the CP45 and other projection room equipment, check the following list for possible causes: Ground loops caused by audio signal wiring, especially to power amplifiers.
  • Page 23 2-12 With CP45 FADER turned up and format 04 selected: 5. Solar cell wiring. Check the shield connections. Cell wiring should be placed away from mains and other wiring. Cell wires must not be connected to the frame of the projector.
  • Page 29 Interior view of CP45, showing modules installed...

  • Page 30: Cat. No. 510/514 Input/Output Card

    2-19 Cat. No. 510/514 Input/Output Card The Cat. No. 510 is the input and output part of the CP45. It has two stereo inputs for optical soundtracks, one mono microphone input, and six outputs for the front screen speakers. The card is normally fitted with a Cat.

  • Page 31: Cat. No. 513 Equalization Board

    2-20 There is also a pair of inputs which can be connected video projectors etc. and which feed the Dolby decoder. This input can also be used for background and intermission music. The board also carries the driver circuitry for the Cat. No. 222A or Cat. No.

  • Page 32: Cat. No. 222A Module

    The Cat. No. 516 is a small remote unit which allows selection of the film format and playback level from a point near the projectors. The connection to the CP45 is via a 15-way screened cable which may share the remote output on the CP45 with an automation system if installed.
  • Page 33 FADER ACTIVE INDICATOR Shows if the front panel fader System System 10 10 BYPASS INDICATOR has been selected. Flashes if the CP45 is in bypass mode. 60 60 Non-sync 1 Non-sync 1 Bypass Bypass The CP45 will automatically switch to bypass if the internal power supply fails.

  • Page 34: Section 3 An Overview Of The Alignment Procedure

    Dolby cinema equipment. It is useful to develop an understanding of why the CP45 is aligned as described in this manual. If the installer is already familiar with these principles, or is in a hurry to complete the installation, this section may be read later. Continue the installation procedure beginning with Section 4.
  • Page 35 Pure pink noise would yield a “flat” horizontal line on the RTA. Thus, the effect of adjustments to the CP45 equalizers is quickly and easily seen. One of the problems inherent in equalization is the nature of the environment.
  • Page 36 The amount of reverberation varies with frequency and the higher the frequency the more the treble will be absorbed rather than being reflected. A typical reverberation curve in a theater rolls off at about 3 dB per octave above 2 kHz. This characteristic is used to define the standard steady-state response curve for all dubbing theaters in which films with Dolby soundtracks are mixed and for all Dolby processor-equipped cinemas.

  • Page 37: Section 4 A-Chain Alignment

    The A-chain is the part of the sound system that covers the film path, solar cell, optical preamplifier, slit loss equalizer and Dolby processing circuit. The CP45 does not contain a magnetic A-chain but has facilities for switching external magnetic preamplifiers into the B-chain via the Aux inputs. These inputs may also be used for connecting digital film sound processors such as the Dolby Model DA20.

  • Page 38: A. Preliminary Procedures

    A-Chain Alignment Procedures a. Preliminary Procedures Step Action Indication...
  • Page 39 A-Chain Alignment Procedures a. Preliminary Procedures Notes If a stereo solar cell is already installed on Projector No. 1, inspect the surface of the cell for cracks, chipping, or other damage. If the cell appears to require replacement, remove the mounting bracket from the projector and replace the cell and mounting block assembly.
  • Page 40 A-Chain Alignment Procedures a. Preliminary Procedures Step Action Indication 70 TO 80% OF RATED VOLTAGE...
  • Page 41 A-Chain Alignment Procedures a. Preliminary Procedures Notes Remove the existing exciter lamp and replace with a new lamp. Adjust the exciter lamp DC voltage to 70% to 85% of the rated voltage and verify that there is no more than 3% ripple present with the lamp on, using an AC millivolt meter or oscilloscope.

  • Page 42: B. Optical Preamplifier Adjustments

    A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step Action Indication PROJECTOR 1 PROJECTOR 2 HIGH HIGH HIGH HIGH HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ FREQ FREQ FREQ FREQ LEFT LEFT RIGHT RIGHT LEFT LEFT RIGHT RIGHT LEVEL LEVEL LEVEL LEVEL LEVEL...
  • Page 43 Confirm that the cell wiring and connections are correct. Shielded cables must be used. The inner conductors must be wired to the CP45 PROJECTOR input connectors exactly as shown on the wiring diagram fold-out.
  • Page 44 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step Action Indication PROJECTOR 1 PROJECTOR 2 HIGH HIGH HIGH HIGH HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ FREQ FREQ FREQ FREQ LEFT LEFT RIGHT RIGHT LEFT LEFT RIGHT RIGHT LEVEL LEVEL LEVEL LEVEL LEVEL...
  • Page 45 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Notes On the Cat. No. 510 Card: Turn all of the Proj 1 and Proj 2 high freq potentiometers fully counterclockwise (CCW). Verify that power to the power amplifiers are OFF. Press the format 04, Dolby Stereo A-Type switch on the front panel; the LED in the switch should light.
  • Page 46 4-10 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step Action Indication PROJECTOR 1 PROJECTOR 2 HIGH HIGH HIGH HIGH HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ FREQ FREQ FREQ FREQ RIGHT RIGHT RIGHT RIGHT LEFT LEFT LEFT LEFT Dual SR/A Decoder Module Dual SR/A Decoder Module Cat.No.222SR/A Cat.No.222SR/A...
  • Page 47 4-11 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Notes Thread and play the Cat. No. 69T Dolby Tone test film for an initial test of the signal path through the projector preamplifier. The film emulsion should face away from the screen. Adjust the Cat.
  • Page 48 4-12 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step Action Indication CAT. NO. 97 TEST FILM OSCILLOSCOPE TRACE Dual SR/A Decoder Module Dual SR/A Decoder Module Cat.No.222SR/A Cat.No.222SR/A REPEAT...
  • Page 49 4-13 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Notes Remove the SMPTE Buzz Track Film and thread and play the Cat. No. 97 Stereo Cell Alignment Film. While the film is playing, look at the oscilloscope. If a large amount of crosstalk is present, loosen the stereo solar cell head and move the head from side to side until the crosstalk is minimum and equal.
  • Page 50 4-14 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step Action Indication 1 12 OSCILLOSCOPE TRACES Cat. No. 510 Cat. No. 510 IN IN Out of phase OSCILLOSCOPE OSCILLOSCOPE SET TO X/Y MODE Incorrect azimuth 1 13 INTO FOCUS –5 OUT OF FOCUS –10 12.5...
  • Page 51 4-15 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Notes Thread and play the pink noise on the Cat. No. 69 film (emulsion away from screen). Connect the RTA to the left test point L on the Cat. No. 510. Switch the oscilloscope to the X/Y mode and adjust the azimuth of the projector optics for the narrowest diagonal trace.
  • Page 52 4-16 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step Action Indication Cat. No. 510 Cat. No. 510 IN IN OSCILLOSCOPE OSCILLOSCOPE 1 12 1 13 REPEAT PROJECTOR 1 PROJECTOR 2 HIGH HIGH HIGH HIGH HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ FREQ...
  • Page 53 4-17 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Notes Disconnect the RTA from the left test point and connect it to the right test point R. Then repeat Steps 12 and 13. NOTE: The azimuth and high frequency response must be the same at both the left and right test points. If results are not similar, it may be necessary to remove the lens and check for oil or contamination or a degraded slit.
  • Page 54 4-18 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step Action Indication PROJECTOR 1 PROJECTOR 2 Dual SR/A Decoder Module Dual SR/A Decoder Module Cat.No.222SR/A Cat.No.222SR/A HIGH HIGH HIGH HIGH HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ FREQ FREQ FREQ FREQ LEFT LEFT...
  • Page 55 4-19 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Notes Thread and play the Cat. No. 69T Dolby Tone test film. Verify that the Dolby tone indication is shown on the Cat. No. 222 SR/A card (the center two green LEDs are lit for both the R and L channels). If necessary, re-adjust the Proj 1 left and right gain controls on the Cat.

  • Page 56: B-Chain Alignment

    SECTION 5 B-CHAIN ALIGNMENT Check Theater Equipment Thoroughly check the loudspeakers and power amplifiers for sources of poor performance: • Check that the loudspeaker cables are in good condition and that they of a suitable gauge for the impedance of the speakers and the length of the run. •...

  • Page 57: Setting Room Equalization

    B-Chain Alignment Procedures 5.2 Setting Room Equalization Step Action Indication POWER AMPS Bypass Bypass Bypass Bypass Normal Normal POWER AMP...
  • Page 58 — 5 feet off the floor level — and angled 45 degrees upward toward the screen. Connect the microphone to the RTA. Set the front panel NORMAL/BYPASS switch on the CP45 BYPASS. Turn power ON to the power amplifiers.
  • Page 59 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step Action Indication Fader Fader 10 10 fader fader active active Bypass Bypass Normal Normal 04 04 Dolby Stereo A-type Dolby Stereo A-type 64 64 05 05 Dolby Stereo SR Dolby Stereo SR Signal Signal Left...
  • Page 60 B-Chain Alignment Procedures 5.2 Setting Room Equalization Notes Set the FADER to the 0 position. Verify that the fader local active LED is on. If necessary, press the FADER ACTIVE switch. Set the NORMAL/BYPASS switch to the NORMAL position. Simultaneously press and hold the 04 and 05 switches until the mic LED lights (approximately 7 seconds).
  • Page 61 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step Action Indication PROJECTOR 2 PROJECTOR 2 PROJECTOR 1 PROJECTOR 1 75-80 dBC OUTPUTS OUTPUTS HIGH HIGH HIGH HIGH HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ FREQ FREQ FREQ FREQ TRIM TRIM TRIM TRIM TRIM...
  • Page 62 B-Chain Alignment Procedures 5.2 Setting Room Equalization Notes Open the CP45 front panel. With a sound pressure level meter located at the position in the theatre used for step 6, adjust the center channel level control on the Cat. No. 510 card until the channel produces a reading of 75-80 dBC.
  • Page 63 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step Action Indication Left –5 –10 3.15 12.5 Center –5 –10 12.5 3.15 Right –5 –10 12.5 3.15 NORM SUB MUTE LEFT J501 J502 100Hz BASS 110Hz 190Hz 330Hz 580Hz 1kHz 1.8kHz TREBLE 63Hz 50Hz BASS...
  • Page 64 B-Chain Alignment Procedures 5.2 Setting Room Equalization Notes Compare the response displayed on the real time analyzer (RTA) for each channel (L, C, R). All should show a similar shape. Any large differences indicate faulty or misaligned crossovers or defective speakers. Speaker phasing could also be at fault.
  • Page 65 5-10 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step Action Indication Signal Signal 04 04 Dolby Stereo A-type Dolby Stereo A-type Left Left Center Center Right Right Surround Surround Subwoofer Subwoofer 05 05 Dolby Stereo SR Dolby Stereo SR Signal Signal Left Left...
  • Page 66 5-11 B-Chain Alignment Procedures 5.2 Setting Room Equalization Notes Cycle the pink noise to the center channel. While observing the RTA, adjust the bass controls on the EQ board so that the bass frequency response is as flat as possible. The left hand L.F.
  • Page 67 5-12 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step Action Indication NORM SUB MUTE LEFT J501 J502 100Hz BASS 63Hz 110Hz 190Hz 330Hz 580Hz 1kHz 1.8kHz TREBLE 50Hz BASS TREBLE FREQ MARK EACH POT ARROW POSITION FREQ FREQ CENTER BASS 63Hz 110Hz 190Hz...
  • Page 68 5-13 B-Chain Alignment Procedures 5.2 Setting Room Equalization Notes Adjust the treble controls on the EQ board for as flat a response as possible up to 2 kHz, followed by a 3 dB per octave roll-off above 2 kHz. The right hand H.F. control sets the frequency range. The left hand H.F. control sets the boost or cut.
  • Page 69 5-14 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step Action Indication REPEAT...
  • Page 70 5-15 B-Chain Alignment Procedures 5.2 Setting Room Equalization Notes If the sound quality varies significantly as you walk around, the equalization has not been adequate: • You may have over equalized. Check the positions of the controls; all should be as close to 12 o’clock as possible. •...

  • Page 71: Adjusting L,C,R Output Levels

    5-16 B-Chain Alignment Procedures 5.3 Adjusting L,C,R Output Levels Step Action Indication PROJECTOR 1 PROJECTOR 1 PROJECTOR 2 PROJECTOR 2 OUTPUTS OUTPUTS 85 dBC HIGH HIGH HIGH HIGH HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ FREQ FREQ FREQ FREQ TRIM TRIM TRIM...
  • Page 72 5-17 B-Chain Alignment Procedures 5.3 Adjusting L,C,R Output Levels Notes Cycle the pink noise and adjust the L, C and R level controls on the Cat. No. 510 so that each channel produces 85 dBc in the theatre, as measured by the sound level meter at the location described in step 15 above.

  • Page 73: Subwoofer Alignment

    5-18 B-Chain Alignment Procedures 5.4 Subwoofer Alignment Step Action Indication J502 NORM SUB MUTE J501 Cat. No. 513 100Hz 1kHz 1.8kHz TREBLE 50Hz TREBLE FREQ FREQ 1kHz TREBLE 1.8kHz TREBLE FREQ Signal Signal Left Left 04 04 Dolby Stereo A-type Dolby Stereo A-type Center Center...
  • Page 74 5-19 B-Chain Alignment Procedures 5.4 Subwoofer Alignment Notes Confirm that the microphone is in the position defined on page 5-7. All connections established in the room equalization procedure apply to the following steps. Insure that the NORM/SUB MUTE jumper on the EQ board is in the NORM position.
  • Page 75 5-20 B-Chain Alignment Procedures 5.4 Subwoofer Alignment Step Action Indication Fader Fader 10 10 MONO MODE MONO MODE ENHANCE NORM ENHANCE NORM NS1 MODE MATRIX NORMAL NORMAL MATRIX SURROUND SURROUND OUTPUT LEVEL NS1 INPUT LEVEL S1 INPUT LEVEL DELAY SURR +6.7V -6.7V SURR...
  • Page 76 5-21 B-Chain Alignment Procedures 5.4 Subwoofer Alignment Notes Slowly advance the fader to position 7. The subwoofer and center channel response should be observed on the RTA. Adjust the subwoofer output level control on the Cat. No. 511 to match the level of the midrange frequencies.
  • Page 77 5-22 B-Chain Alignment Procedures 5.4 Surround Alignment Step Action Indication Fader Fader 10 10 04 04 Dolby Stereo A-type Dolby Stereo A-type Signal Signal Left Left Center Center 05 05 Dolby Stereo SR Dolby Stereo SR Right Right Surround Surround Subwoofer Subwoofer Fader...
  • Page 78 5-23 B-Chain Alignment Procedures 5.4 Surround Alignment Notes Confirm that the microphone is in the position defined on page 5-3 All connections established in the room equal. procedure apply to the following steps. Set the fader to position 0. Cycle the pink noise to the surround channel. Slowly advance the fader to position 7.
  • Page 79 5-24 B-Chain Alignment Procedures 5.4 Surround Alignment Step Action Indication 85 dBC Fader Fader 10 10 RIGHT SURROUND POWER AMP Fader Fader 10 10...
  • Page 80 5-25 B-Chain Alignment Procedures 5.4 Surround Alignment Notes Adjust the surr output control for a sound pressure level of approximately 85 dBC in the theatre. Set the fader to position 0. Turn off the Rs power amplifier. Set the fader to position 7.
  • Page 81 5-26 B-Chain Alignment Procedures 5.4 Surround Alignment Step Action Indication Cat. No. 513 Cat. No. 513 TREBLE TREBLE BASS BASS –5 –10 12.5 3.15 Fader Fader 10 10 RIGHT SURROUND AMP LEFT SURROUND AMP Fader Fader 10 10...
  • Page 82 5-27 B-Chain Alignment Procedures 5.4 Surround Alignment Notes Adjust the Left Surround EQ controls on the EQ board to match the figure as closely as possible. Use caution when adjusting the bass control; many surround loudspeaker systems are deficient in their low frequency response. Attempts to boost the output of such systems beyond their capabilities simply wastes amplifier power and can result in distortion and possibly damage to the surround loudspeakers.
  • Page 83 5-28 B-Chain Alignment Procedures 5.4 Surround Alignment Step Action Indication Cat. No. 513 Cat. No. 513 BASS BASS TREBLE TREBLE –5 –10 3.15 12.5 Fader Fader 10 10 LEFT SURROUND AMP Fader Fader 10 10 MONO MODE MONO MODE ENHANCE ENHANCE NORM NORM...
  • Page 84 With the microphone still located near the center of the theatre, adjust the surr output control on the Cat. No. 511 card for a sound pressure level of 85 dBC. Press the mic button, format 64, to restore the CP45 to normal operation.
  • Page 85 5-30 B-Chain Alignment Procedures 5.4 Surround Alignment Step Action Indication 04 04 Dolby Stereo A-type Dolby Stereo A-type...
  • Page 86 5-31 B-Chain Alignment Procedures 5.4 Surround Alignment Notes Press format 04 Dolby Stereo A-type. Thread and play the Cat. No. 151 Stereo Optical Surround Level test film. Check the sound by walking around the theatre. The surround and center channels should sound equally loud at most locations and left and right surround channels should sound equally loud and have similar frequency response in the center of the theatre.

  • Page 87: Setting Optical Surround Delay

    Action Indication The CP45 incorporates a delay line in the surround channel to ensure that sound from the rear of the theater arrives at the listeners’ ears approximately 20 milliseconds after the arrival of sound from the front speakers. The delay is set into the Cat. No. 511 card via a rotary switch.
  • Page 88 Do not be tempted to increase the surround level because the effect desired by the film production team may be impaired or destroyed. Connect a cassette deck or CD player to the from non sync terminals on terminal block TB6 on the backplane of the CP45.

  • Page 89: Non-Sync Level Adjustment

    5-34 B-Chain Alignment Procedures 5.6 Non-sync Level Adjustment Step Action Indication Model CP45 Model CP45 60 60 Non-sync 1 Non-sync 1 Fader Fader 10 10 fader fader active active MONO MODE MONO MODE ENHANCE ENHANCE NORM NORM NS1 MODE NS1 MODE...
  • Page 90 Press the format 60 non sync switch. Check that the local FADER is selected—the local active LED on the CP45 is lit. If necessary, select the local FADER by pressing the fader select switch.

  • Page 91: Final Check

    6 minutes Picture format: 1.85:1 widescreen or 2.35:1 anamorphic Sound formats: digital analog Dolby Laboratories Inc. • 100 Potrero Avenue San Francisco, CA 94103-4813 Telephone 415-558-0200 • Facsimile 415-863-1373 Dolby and the Double-D symbol are trademarks of Dolby Laboratories S96/10117/11146...
  • Page 92 The film consists of a wide variety of short scenes—both live action and animated. Each scene was selected to demonstrate different aspects of stereo sound. Evaluate the quality of the sound. If problems occur, contact the technical staff at Dolby Laboratories.

  • Page 93: Reference Diagrams

    SECTION 6 REFERENCE DIAGRAMS...
  • Page 96 APPENDIX A EFFECT OF CHANGES IN SLIT HEIGHT ON SLIT LOSSES The slit has a finite height that cannot be reduced without a simultaneous reduction in the light output and, thus, the electrical output of the system. The exciter lamp supply output could be increased in an effort to compensate, but this would shorten the life of the lamp.

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