Dolby Laboratories CP45 User Manual
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Dolby Laboratories CP45 User Manual

Dolby Laboratories CP45 User Manual

Cinema processor
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MODEL CP45
CINEMA PROCESSOR
Users' Manual

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Summary of Contents for Dolby Laboratories CP45

  • Page 1 MODEL CP45 CINEMA PROCESSOR Users' Manual...
  • Page 2 U.S.A. 100 Potrero Avenue, San Francisco, CA 94103 Tel: 415-558-0200; Fax: 415-863-1373 U.K. Wootton Bassett, Wiltshire SN4 8QJ, England Tel: 01793-842100; Fax: 01793-842101 Dolby is a registered trademark of Dolby Laboratories Licensing Corporation. ©1995 Dolby Laboratories ISSUE 1 S95/10750 Dolby Part No. 91388...

  • Page 3: Table Of Contents

    HOW TO TELL A STEREO OPTICAL PRINT FROM A MONO PRINT ......................A-1 APPENDIX B DOLBY TEST AND DEMONSTRATION FILMS ............B-1 1. Cat. No.69T: Dolby Tone ................B-1 2. Cat. No.251: Jiffy Test Film ................B-1 3. Cat. No.351 Stereo Demonstration Film: “listen . . .” ....... B-3...
  • Page 4 ABOUT DOLBY FILM SOUND FORMATS ..............D-1 1. How Dolby Noise Reduction Works.............. D-1 2. About Dolby SR ....................D-1 3. Why the Dolby Level Adjustment Is Important .......... D-3 4. The Consumer Dolby Noise Reduction Systems......... D-3 APPENDIX E HOW FOUR CHANNELS ARE DERIVED FROM DOLBY STEREO OPTICAL PRINTS ...................

  • Page 5: Introduction

    It was necessary, for example, to electronically “fold” four sound channels into just two physical tracks on the film, and then “unfold” (decode) them on playback in the theatre. Dolby noise reduction, a form of signal processing that greatly expands the limited dynamic range of optical soundtracks, was also used, and requires its own special playback processing circuitry.

  • Page 6: Section

    About This Manual This Users’ Manual has been prepared specifically to help projectionists get the most from the Model CP45 and the theatre sound system once it has been installed and aligned. (Installation and alignment instructions are supplied to the local distributor or installation company). We suggest that you keep this manual readily available.
  • Page 7 • The Appendices contain valuable background information which will help you to get the most out of the Model CP45 and your theatre sound system. For the sake of clarity, boldface type is used for all specific references to the CP45 controls and their labels, such as Bypass, and front-panel Fader.

  • Page 8: Operating Instructions

    NORMAL OPERATION Initial Power-Up Each time the CP45 is connected to power, it automatically sets itself to the format it was in when power was removed unless the power has been removed for more than a week. Under these circumstances the wake-up state is: •...
  • Page 9 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 10: Remote Faders

    03 “Dolby Stereo without surround,” select format 04 Dolby A- type. Front Panel (Local) Fader The fader on the front panel of the CP45 controls the volume level in the theatre in all operating modes. After the CP45 has been correctly installed, setting the fader to 7 will play a Dolby film at the level at which it was mixed.

  • Page 11: Operation With Automation System

    If the CP45 in your theatre is connected to automation equipment, the format buttons and their associated LEDs may be duplicated elsewhere. In most cases, the front panel controls of the CP45 can usually be used to override commands from the automation system; however, as...
  • Page 12 NOTE The CP45 will not operate even in the bypass mode if there is a fault in the mains supply to the bypass transformer and may not operate if there is a fault in either the Cat.
  • Page 13 All other controls are for use by a trained engineer when the CP45 is first installed or repaired. Adjusting these controls requires t h e u s e o f s p e c i a l t e s t e q u i p m e n t .

  • Page 14: Maintenance And Adjustments

    SECTION 2 MAINTENANCE AND ADJUSTMENTS The installation of the Dolby CP45 in your theatre indicates a commitment to providing a high-quality presentation to your audiences. However, the presence of even the very best equipment does not in itself guarantee the best results. A number of routine maintenance and adjustment...

  • Page 15: Print Cleanliness

    Proper decoding of soundtracks encoded with Dolby A-type or SR processors requires careful level matching between each channel of each soundhead and the CP45 (see Appendix D for a discussion of Dolby noise reduction and why Dolby Level is important). When the CP45 is first installed, the installer makes this adjustment for you.
  • Page 16 The film must run in the direction of the printed arrow. 4. Open the front panel of the CP45 using a screwdriver. 5. Locate the Cat. No. 510 card and Cat. No. 222 noise reduction module. (Dolby Level adjustments are made on the Cat.
  • Page 17 If you happen to play the test film with a stereo optical format (04 or 05) selected after Dolby Level has been correctly adjusted, you may notice that the pairs of green LEDs are not equally lit or that one or both of the left hand side LEDs goes out completely.

  • Page 18: Troubleshooting

    In addition, Appendix C contains brief descriptions of each circuit module, which will further help you to track down any problems with the CP45. If you are unable to solve the problem using the information which follows, call your local authorized service engineer.

  • Page 19: If One Channel Fails Or Is Distorted

    If One Channel Fails or is Distorted Switch the CP45 to bypass; a mono signal is then fed to all three screen channels. If the distortion persists in one channel, the power amplifier or speaker for that channel is probably at fault and the amplifier for that channel should be switched off for the remainder of the show.

  • Page 20: Excessive Or Inappropriate Sound From The Surround Speakers

    If you have a spare, disconnect power from the CP45, switch off the power amplifiers, and replace the Cat. No.510 in the CP45 with the spare. Apply power to the CP45 and turn on the power amps to see if sound is restored.

  • Page 21: When The Theatre Is Closed

    If you can take the time, the following procedures may help you to track down which part of the CP45 may be the cause of the trouble. If you have to telephone your service engineer, the information you obtain can reduce the time required for him to correct the malfunction.
  • Page 22 There is sound. lies flat when plugged in. No LEDS on the front panel are lit. Main board inside the CP45 is unplugged Remove the main power block only from the Power LED's on front edge of the mains supply, open the front panel and plug main board are off.
  • Page 23 Redirect the light from the last source or keep it off during a showing. If the hum still is present, the problem is either in the grounding or wiring or in the CP45. Call service engineer.
  • Page 24 If the signal present LEDs on the Cat. No. 222A/SR module are flashing, but the ones on the front panel are not, the problem is caused by a malfunctioning card or module in the CP45. Switch to Bypass and call service engineer.
  • Page 25 Check if the amplifier concerned is on and check for blown fuses. Check that the wiring from the CP45 to the amplifier or the loudspeaker wiring have not been broken or disconnected; check that the screws connecting the wiring on the back panel are properly tightened.
  • Page 26 Check that the cards are all properly seated in their connectors, especially the 222A/SR module under the main board. Wiring from the stereo solar cell to the CP45. Check that the wiring from the stereo solar cell to the CP45 has not become kinked and that the solder connections to the fanning strip are secure.
  • Page 27 D. TROUBLESHOOTING PROCEDURES (cont'd) Trouble Probable Cause Recommended Action When a stereo film is projected, The A-chain has become misaligned. Call service engineer. the sound appears to be coming from the wrong speakers. You can hear pops and thumps If your projector changeover relay power is DC, If possible, check that the diode is installed during projector changeover.
  • Page 28 If the distortion goes away, you have found the problem. If changing both the device and the selection does not eliminate the distortion, the problem is in the CP45. Call service engineer. Malfunctioning Cat. No. 512 main board.
  • Page 29 Malfunctioning Cat. No.510 optical Call service engineer. preamplifier. The sound output of the CP45 is Fader connector unplugged from CAT No 510 Plug fader connector back into the 2 pin at a medium level, regardless of optical preamp board.
  • Page 30 Unplug the D-connector from the back of the connected to the CP45: CP45. If you can exercise local control over the CP45, the problem is in either the Cat. No. 511, The CP45 freezes into one format Incorrect wiring to D-connector plugged into...

  • Page 31: How To Tell A Stereo Optical Print From A Mono Print

    HOW TO TELL A STEREO OPTICAL PRINT FROM A MONO PRINT A Dolby encoded optical print should be identified as such on both the film can and leader. However, with handling the identification may be lost. If you are not sure if you have a stereo print, play a reel and find a section with music and/ or effects only (on dialogue or narration, stereo soundtracks look much the same as mono soundtracks).

  • Page 32: Dolby Test And Demonstration Films

    Cat. No. 69T: Dolby Tone This film is required to maintain your theatre system. The Dolby Tone recorded on the film is for adjusting Dolby Level as instructed on page 2-2; this simple adjustment must be performed whenever an exciter...
  • Page 33 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 Cat. No. 251 Jiffy Test Film listen…...

  • Page 34: Cat. No.351 Stereo Demonstration Film: "Listen

    Cat. No. 351 Stereo Demonstration Film: “listen . . .” “listen . . .”, an eight-minute Dolby Stereo demonstration film for public exhibition, has been professionally produced to demonstrate the commitment of the theatre to providing its audiences with the best in both sound and picture.

  • Page 36: Cp45 Module Descriptions

    CP45 MODULE DESCRIPTIONS 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 37 The Cat. No. 515 is a small board that is mounted on the Cat. No. 511 main board when stereo surround operation is desired. Cat. No. 222 Module This module provides two channels of Dolby A-type noise reduction for the soundtracks. Cat. No. 222 SR/A Module This module provides two channels of either Dolby A-type noise reduction or Dolby SR processing for the soundtracks.

  • Page 38: About Dolby Film Sound Formats

    (e.g., it does not turn down the treble as filters do). Dolby noise reduction is a two-step process used both at the time a recording is made and when it is played back. Just before the signal is recorded, it is processed by the Dolby noise reduction circuitry.
  • Page 39 Fixed Band Fixed Band Sliding Band Sliding Band ----------------- ----------------- Fixed Band Fixed Band (–) (–) (–) (–) (–) LF & HF Signal Anti- Anti- Spectral Output Saturation Saturation Skewing Figure D-2: Dolby Spectral Recording Encoder and Decoder Basic Block Diagram...

  • Page 40: The Consumer Dolby Noise Reduction Systems

    This is where the Dolby Level Tone on the Cat. No. 69 film comes into play. The tone on this film is very carefully recorded at the standard reference Dolby Level.
  • Page 41 (a modified version of B-type noise reduction is also used to encode the surround channel on Dolby Stereo and Dolby Stereo SR release prints). Dolby C-type was later developed to provide more noise reduction than Dolby B-type, and is provided along with B-type in many of today’s high-performance...

  • Page 42: How Four Channels Are Derived From Dolby Stereo Optical Prints

    HOW FOUR CHANNELS ARE DERIVED FROM DOLBY STEREO OPTICAL PRINTS The 35-mm Dolby Stereo optical format calls for the recording in the studio and the reproduction in the theatre of four separate sound channels, — left, center, right, and surround — and yet a Dolby Stereo optical print has only two soundtracks.
  • Page 43 In the theatre, when the signals from the two tracks on a Dolby Stereo print reach the CP45 processor, its 2:4 decoder constantly compares the two signals.

  • Page 44: Appendix Foptical Bass Extension

    The result is smooth, deep bass response which complements the improved mid and upper range response already achieved in your theatre by means of the equalization in the CP45. POWER AMPS BASS...

  • Page 45: Of Dolby Film Sound

    And what the audience hears today is very much the result of a continuing effort to improve film sound originally undertaken by Dolby Laboratories more than twenty years ago. Indeed, the evolution of motion picture sound over the past two decades is, in great part, that of Dolby film sound technologies.
  • Page 46 This caused a dilemma for soundtrack recordists. Should the tracks be recorded to take advantage of the improved speakers, or should they be prepared to sound best on the many older installations already in place? Given that it was impractical to release two versions of a given title, the only alternative was to tailor soundtracks to the older speakers.
  • Page 47 Dolby-manufactured cinema processors with far wider frequency response and much lower distortion than conventional soundtracks. In fact, the Dolby optical format has led to a new worldwide playback standard (ISO 2969) for wide-range stereo prints, just as the “Academy” characteristic applies for mono prints.
  • Page 48 There are six magnetic tracks on 70 mm film, two of which carry low bass effects. Some 70 mm films also use a technique developed by Dolby Laboratories to provide two separate surround channels in addition to the left, center, right, and bass effects screen channels.
  • Page 49 35 mm prints. This Dolby Digital format is yet another significant step forward in film sound, providing independent left, center, right, left surround, and right surround channels, plus a sixth channel for bass effects. In addition to multiple channels, the Dolby Digital track provides extraordinary dynamic capability, wide frequency, range low distortion, and relative immunity to wear and tear.
  • Page 50 The objective is high quality sound reproduction overall–dialogue and music, as well as effects. Dolby technology is a means, not an end. It can be likened to an artist’s palette that provides the director with a full range of colors, where before there were but a few.

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