Model CP45 Cinema Processor Installation and Alignment Manual Issue 2 Part No.
Model DP562 User’s Manual Dolby Laboratories Inc U.S. Headquarters Dolby Laboratories Inc 100 Potrero Avenue San Francisco, CA 94103-4813 Telephone 415-558-0200 Facsimile 415-863-1373 www.dolby.com U.K. European Office Dolby Laboratories Wootton Bassett Wiltshire SN4 8QJ England Telephone (44) 1793-842100 Facsimile (44) 1793-842101 If you purchased the Model DP562 through a dealer or systems integrator, please contact them for technical support.
TABLE OF CONTENTS INTRODUCTION AND SPECIFICATIONS ......................................................................... i SECTION 1 EQUIPMENT REQUIRED ...................................................................................................... 1-1 SECTION 2 INITIAL SET-UP AND INSTALLATION .......................................................................... 2-1 2.1 Replacing an Existing Sound System........................................................................ 2-1 2.1.
SECTION 5 B-CHAIN ALIGNMENT ......................................................................................................... 5-1 5.1 5.2 5.3 5.4 5.5 5.6 5.7 Check Theater Equipment ........................................................................................... 5-1 Setting Room Equalization.......................................................................................... 5-2 Adjusting L,C,R Output Levels ...........................................................................
i INTRODUCTION AND SPECIFICATIONS About The Dolby CP45 The Dolby Model CP45 combines the high performance for which all processors manufactured by Dolby Laboratories are well known with a new cost-effective integrated design. The CP45 is the heart of your theatre sound system. All sound sources are connected to the CP45 which processes their signals appropriately and feeds them to the power amplifiers. The CP45 precisely complements the techniques used in the preparation of Dolby Stereo optical releases.
ii The Dolby Cinema Processor is the central element of the theatre sound system. The projector, the Dolby Processor, the power amplifiers and the loudspeakers, as well as the auditorium itself, must be considered when aligning the system for optimum performance.
iii SPECIFICATIONS Construction Rack-mount chassis frame construction with plug-in modules accessible behind hinged front panel. Signal connections Standard pluggable screw-type terminal blocks for audio signals and control connections for projector changeover. Mating halves supplied for each terminal block. Automation connections via 15-way D-type connector. Power supplied via two outboard wall-mount transformers (one main, one bypass).
1-1 SECTION 1 EQUIPMENT REQUIRED The following equipment is required for proper installation and alignment of the CP45 Cinema Processor. • Dual-trace oscilloscope with X-Y facilities. • 1/3 Octave Real Time Spectrum Analyzer (RTA) with calibrated microphone. (Preferably multiple microphones and a multiplexer should be used.) • Sound Pressure Level Meter (with slow time-constant and C weighting scale). • Voltmeter for measuring the exciter lamp power supply.
1-2 3. 1kHz, 100% Modulation, Left/Right — Cat. No. 97 4. 5. SMPTE Buzz Track Stereo Optical Surround Level — Cat. No.
1-3 6. Illumination Uniformity — Cat. No. 566 JIFFY TEST FILM Cat. No. 251 SR•D—A subjective film for testing theatre sound RECORDED IN Running Time: 6 minutes Picture format: 1.85:1 widescreen or 2.35:1 anamorphic Sound formats: 10 05 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.
2-1 SECTION 2 INITIAL SET-UP AND INSTALLATION Do NOT connect the CP45 to mains power until all connections have been made and all jumpers have been checked or set. If air-conditioning noise is audible in the theater, arrange for lubrication of the motor, fan bearings, adjustment of belts and drives, and cleaning of filters to reduce the ambient noise to a minimum. If the air-conditioning cannot be repaired switch it off while the CP45 is being aligned. 2.
2-2 2.1.3 Disconnect the old system Disconnect power from the existing cinema sound equipment. Mark each cable to an existing sound processor identifying its function, then disconnect the cabling. Leave the cables connected to the power amplifiers, booth monitor, etc. 2.2 Mount the CP45 Open the front panel and confirm that all modules and and circuit cards are seated properly. Close the front panel and cut the cable ties located on the bottom of the unit used for shipping the Cat. No.
2-3 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. If no second surround card (Cat. No. 515) is present, the feeds will be summed to mono and sent to the left surround output. With a Cat. No.
2-4 2.4 Jumpers and Switches 2.4.1 Backplane Jumpers and Switches TEST M J9 BOOTH MONITOR OUTPUT IN OUTPUT LEVEL RANGE HIGH LEFT LF J1 J2 LEFT HF CENTER CENTER LF HF RIGHT LF J3 RIGHT HF L S LOW R S SW HEARING IMPAIRED TEST OUT L C RL S J4 These jumpers set the output signal level range for each channel. They are set at the factory for a power amplifier input sensitivity of between 90 mV and 1.23 V.
2-5 2.4.2 Output Signal Test /Hearing Impaired Signal Select Switches TEST MIX NS1 NS2 IN OUT IN HEARING IMPAIRED TEST BYPASS MIX A CINEMA P MODE OUT L C R L R SW S S J 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. The individual channel switches are not active.
2-6 2.4.3 Cat. No. 513 O J501 SU U J502 100Hz 1kHz 1.8kHz 50Hz TREBLE SUB FREQ 1kHz 1.8kHz TREBLE FREQ 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.
2 -7 J6 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.
2-8 J8 J7 Non-sync 1 mode NORMAL Selects standard non-sync processing. The nonsync signals are sent to the left, center and right screen channels, with a mono mix to the surround channel. 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. The output is sent to the left, center, right, surround and subwoofer channels without noise reduction. This format would be used for playback of video sources.
2-9 OFF Disables the crossover circuitry. Use this switch position when full-range screen speakers and amplifiers are used for Left, Center, and Right screen channels. The CP45 is factory set to the position. Crossover Frequency Setting Switches These switches select the crossover frequency used with biamplified speaker systems connected to the Left, Center, and Right screen channels. 800Hz Should be used for small theaters with small high frequency horns.
2-10 Your projector may be equipped with a Cat. No. 655 LED soundhead. This product has two varieties. One type has a single 8 pin IC on it, the other has two IC’s. Set J1 (projector 1) and/or J2(projector 2) to UNBALANCED if the Cat. No. 655 LED soundhead has ONE IC. This will raise the gain of the optical preamplifier circuit and ensure correct surround decoding. Set J1 (projector 1) and/or J2(projector 2) to BALANCED if the Cat. No.
2.11 2.6 2.7 Connect the Transformers to AC Mains Power a. With the NORMAL/BYPASS switch in the NORMAL position, verify that the BYPASS indicator is off and any one of the format switch indicator LEDs is on. b. Select each format in turn, using the buttons on the front panel and check that the associated LED lights. If either format 04 or 05 LEDs do not remain on when their select buttons are released, then the Cat. No.222 card may be loose. c. Set the NORMAL/BYPASS switch to the BYPASS position.
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. 6. Exciter lamp power supply. Check for ripple on the DC power supply outputs. Some old exciter lamp power supplies and emergency supplies provide AC to the lamp. The resulting hum makes them totally unsuitable for a Dolby film sound system.
Interior view of CP45, showing modules installed
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. No. 514 optical preamplifier card which converts the solar cell signals from the projectors into voltages which are handled by the Cat. No. 510. Gain and equalization for projector slit loss and microphone gain are set by controls on the card.
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. 222SR/A modules and the audio delay circuit for the surround channel. The Low frequency content of the front screen speaker signals is separated and sent to a special output stage to drive a subwoofer if required.
2-21 of left and right surround inputs. In order to get this mix, there is a jumper on the right hand side connector which must be placed as shown on the board. Cat. No. 222A Module This module provides two channels of Dolby A-type noise reduction for the soundtracks. Cat. No. 222SR/A Module This module provides two channels of either Dolby A-type noise reduction or Dolby SR processing for the soundtracks. Cat. No. 516 Remote Unit The Cat. No.
Normal fader setting. FORMAT 01 FORMAT 04 For mono optical soundtracks. For Dolby Stereo SR For Dolby Stereo soundtracks except those marked SR or SR•D. soundtracks. FORMAT 05 FRONT PANEL FADER Controls the auditorium level when selected. The control should be set at or near 7 for normal operation.
3-1 SECTION 3 AN OVERVIEW OF THE ALIGNMENT PROCEDURE This section is an overview of the general principles involved in the alignment of 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. 3.
3-2 It is not practical for the entire cinema industry to standardize on a single make and model of loudspeaker. In any event, the different acoustical characteristics of individual theaters would, to some extent, negate any such standardized speakers. Electronic equalization of each loudspeaker system achieves consistent results in a broad spectrum of environments, and with a broad range of speakers. Accurate equalization requires the use of standardized acoustic measurement procedures.
3-3 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.
4-1 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.
4-2 A-Chain Alignment Procedures a. Preliminary Procedures Step No.
4-3 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. Clean the lens surfaces with a cotton swab moistened with glass cleaner.
4-4 A-Chain Alignment Procedures a. Preliminary Procedures Step No.
4-5 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. LAMP VOLTAGE 6V 9V DC ADJUSTMENT 4-5 volts 6.
4-6 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step No. Action Indication 1 2 3 PROJECTOR 1 PROJECTOR 2 HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ MIC RIGHT RIGHT LEFT LEFT LEVEL LEVEL LEVEL LEVEL LEVEL GND LEFT RIGHT Cat. No.
4-7 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Notes Loosely install the stereo solar cell bracket on the projector. Position the bracket carefully until the surface of the cell is 1 mm from the film plane surface. Note that if this distance is exceeded, there will be crosstalk between the two optical stereo tracks. Check the image of the slit on the cell. The image should be a thin sharp line.
4-8 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step No. 4 Action Indication PROJECTOR 1 PROJECTOR 2 HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ MIC RIGHT RIGHT LEFT LEFT LEVEL LEVEL LEVEL LEVEL LEVEL GND LEFT RIGHT Cat. No. 510 Do lby 5 04 Dolby Stereo A-type 6 GND L R Cat. No.
4-9 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. Connect the RTA and the oscilloscope to the Cat. No. 510 L (left) and R (right) test points as shown in the interconnection diagram.
4-10 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step No. Action Indication 7 PROJECTOR 1 PROJECTOR 2 HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ MIC RIGHT RIGHT LEFT LEFT LEVEL LEVEL LEVEL LEVEL LEVEL Dual SR/A Decoder Module Cat.No.222SR/A Cat.No.222SR/A SR SR A R L GND LEFT RIGHT Cat. No.
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. No. 510 Proj 1 L and R gain potentiometers until the LEDs on the Cat. No. 222SR/A Decoder Module indicate that Dolby level — the center two green LEDs are lit.
4-12 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step No. Action Indication 9 CAT. NO. 97 TEST FILM OSCILLOSCOPE TRACE 10 Dual SR/A Decoder Module Cat.No.
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. (The right channel is the track toward the outside of the projector.
4-14 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step No. Action Indication 1 12 OSCILLOSCOPE TRACES ✓ GND L R Cat. No. 510 RTA IN X x Out of phase x Incorrect azimuth Y ➤ OSCILLOSCOPE SET TO X/Y MODE 13 1 dB +10 +5 INTO FOCUS ✓ 0 –5 OUT OF FOCUS X 1.6 3.15 –10 .05 .1 .2 .4 .8 RTA DISPLAY 6.3 12.
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. (Blooming at the ends of the trace may be caused by improper lighting of the edges of the optical tracks.
4-16 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step No. 14 Action GND L R Indication Cat. No. 510 RTA IN X Y OSCILLOSCOPE 1 AND 13 REPEAT 12 1 15 dB +10 +5 ✓ PROJECTOR 1 PROJECTOR 2 HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ MIC RIGHT RIGHT LEFT LEFT LEVEL LEVEL LEVEL LEVEL LEVEL GND LEFT 0 –5 –10 RIGHT .05 .1 .2 .4 .8 1.6 3.15 6.3 12.5 kHz Cat. No. 510 dB +10 +5 Do lby X 0 –5 –10 .05 .1 .2 .4 .8 1.6 3.15 6.3 12.
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. Replace the lens, if necessary.
4-18 A-Chain Alignment Procedures b. Optical Preamplifier Adjustments Step No. Action Indication 16 PROJECTOR 1 PROJECTOR 2 Dual SR/A Decoder Module HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ MIC RIGHT RIGHT LEFT LEFT LEVEL LEVEL LEVEL LEVEL LEVEL GND LEFT L RIGHT Cat. No. 510 Do lby 17 FOR PROJECTOR NO. 2 REPEAT 1 → 16 Cat.No.222SR/A Cat.No.
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. No. 240A card. Do not re-adjust the hf controls. Repeat all of the above steps for projector No. 2.
5-1 SECTION 5 B-CHAIN ALIGNMENT 5.1 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. • Rattles (a leak in the woofer cabinet may appear to be a rattle). • Loose bolts or other hardware. • Open drivers.
5-2 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step No.
5-3 B-Chain Alignment Procedures 5.2 Setting Room Equalization Notes 5.2 Room Equalization Equalization is performed using the real-time analyzer and a calibrated microphone(s). The adjustment for the full range channels involves setting 7band equalizer controls for each of the screen channels (left, center, and right), and a 3 band equalizer for the surround channel(s). The ideal setting is reached when the room response readings on the RTA match the standard curves shown in this manual.
5-4 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step No.
5-5 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). When the 04 and 05 switches are released, the mic's LED will flash and internally generated pink noise will automatically cycle L,C,R,S,L…etc.
5-6 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step No. Indication Action 6 PROJECTOR 1 PROJECTOR 2 HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ MIC RIGHT RIGHT LEFT LEFT LEVEL LEVEL LEVEL LEVEL LEVEL RIGHT CENTER RIGHT F F 80 0 3 O 40 LEFT Cat. No.
5-7 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. (After room equalization for all channels is adjusted, the sound pressure level will be set to 85 dBC.) The pink noise should be at least 20 dB above the background noise level of the theatre.
5-8 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step No. Indication Action 10 dB +10 +5 Left 0 –5 2.0 .05 .1 .4 .2 1.6 .8 –10 8.0 6.3 3.15 12.5 kHz dB +10 +5 Center 0 –5 2.0 .05 .1 .4 .2 1.6 .8 –10 8.0 6.3 3.15 12.5 kHz dB +10 Right +5 0 –5 2.0 .05 .1 .4 .2 1.6 .8 –10 8.0 6.3 3.15 12.5 kHz 11 NORM SUB MUTE LEFT J501 J502 100Hz BASS 110Hz 63Hz BASS FREQ 190Hz 330Hz 580Hz 1kHz 1.
5-9 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. See Appendix A. Set the EQ controls on the EQ board (inside the front panel) to 12 o'clock. Move the NORM/SUB MUTE jumper on the EQ board to SUB MUTE.
5-10 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step No. Indication Action 13 Signal 04 Dolby Stereo A-type Left Center Right Surround Subwoofer 05 Dolby Stereo SR Signal Left Center Right Surround Subwoofer 14 dB NORM SUB MUTE LEFT +10 J501 J502 100Hz BASS 63Hz 110Hz BASS FREQ 190Hz 330Hz 580Hz 1kHz 1.8kHz 50Hz TREBLE SUB FREQ MARK EACH POT ARROW POSITION TREBLE FREQ +5 CENTER BASS 63Hz 110Hz 190Hz 330Hz 580Hz 1kHz 1.
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. control sets the frequency range. The right hand L.F. control sets the boost or cut. Next, adjust the H.F. trim control on the Cat. No. 510 card so that the level of the H.F. section of the curve matches the level of the midfrequency section.
5-12 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step No. Indication Action 16 dB +10 NORM SUB MUTE LEFT J501 J502 100Hz BASS 63Hz 110Hz 190Hz BASS FREQ 330Hz 580Hz 1kHz 1.8kHz 50Hz TREBLE SUB FREQ MARK EACH POT ARROW POSITION TREBLE FREQ +5 CENTER BASS 63Hz 110Hz 190Hz 330Hz 580Hz 1kHz 1.
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. The next step is to fine-tune the equalization by adjusting the EQ controls on the EQ board.
5-14 B-Chain Alignment Procedures 5.2 Setting Room Equalization Step No.
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.
5-16 B-Chain Alignment Procedures 5.3 Adjusting L,C,R Output Levels Step No. 21 Indication Action PROJECTOR 1 PROJECTOR 2 OUTPUTS HIGH HIGH HIGH HIGH FREQ FREQ FREQ FREQ MIC RIGHT RIGHT LEFT LEFT LEVEL LEVEL LEVEL LEVEL LEVEL GND LEFT 85 dBC HF HF HF TRIM TRIM TRIM LEVEL LEVEL LEVEL RIGHT CENTER RIGHT LEFT Cat. No. 510 y lb Do 22 Fader 5 4 6 3 7 2 8 1 9 0 10 23 J502 NORM SUB MUTE J501 Cat. No. 513 100Hz 1kHz 1.8kHz TREBLE 50Hz TREBLE FREQ SUB FREQ 1kHz 1.
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. Set the fader to position 0. Return the NORM/SUB MUTE jumper to NORM.
5-18 B-Chain Alignment Procedures 5.4 Subwoofer Alignment Step No. Indication Action 24 25 J502 NORM SUB MUTE J501 Cat. No. 513 100Hz 1kHz 1.8kHz TREBLE 50Hz TREBLE FREQ SUB FREQ 1kHz 1.
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. Cycle the pink noise to the center channel.
5-20 B-Chain Alignment Procedures 5.4 Subwoofer Alignment Step No. Indication Action 21 Fader 4 5 6 3 7 2 8 1 9 0 10 25 MONO MODE ENHANCE NORM NS1 MODE MATRIX NORMAL SURROUND OUTPUT LEVEL DELAY SURR SURR SUB SUB 345 67 +6.7V -6.7V +12V -12V BC D Cat. No.
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. While observing the RTA, note the change in the average level of the bands from 20 Hz to 100 Hz when the subwoofer is turned on and off via the norm/ test connector on the EQ board.
5-22 B-Chain Alignment Procedures 5.4 Surround Alignment Step No.
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.
5-24 B-Chain Alignment Procedures 5.4 Surround Alignment Step No.
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.
5-26 B-Chain Alignment Procedures 5.4 Surround Alignment Step No. Indication Action dB 37 +10 Cat. No. 513 BASS MID TREBLE +5 0 –5 2.0 .05 38 Fader 4 5 6 3 7 2 8 1 9 0 39 10 RIGHT SURROUND AMP ON LEFT SURROUND AMP OFF 40 Fader 4 5 6 3 7 2 8 1 9 0 10 .1 .2 .4 .8 1.6 –10 8.0 3.15 6.3 12.
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. The equalizer controls interact.
5-28 B-Chain Alignment Procedures 5.4 Surround Alignment Step No. Indication Action Cat. No. 513 BASS TREBLE MID dB +10 41 +5 0 –5 2.0 .05 42 .2 .1 .4 .8 1.6 Fader 4 5 6 3 7 2 8 1 9 0 10 LEFT SURROUND AMP ON Fader 4 5 6 3 7 2 8 1 9 0 43 10 MONO MODE ENHANCE NORM NS1 MODE 85 dBC MATRIX NORMAL OUTPUT LEVELSURROUND DELAY SURR SUB 345 y lb Do 44 64 Mic 0 3 80 40 F 70 F 50 O 60 BCD Cat. No. 511 789A E 6 +6.7V -6.
5-29 B-Chain Alignment Procedures 5.4 Surround Alignment Notes Adjust the right surr EQ controls on the EQ board to match the figure curve as closely as possible. Set the fader to position 0. Turn on the Ls power amplifier. Set the fader to position 7. 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.
5-30 B-Chain Alignment Procedures 5.4 Surround Alignment Step No.
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.
5-32 B-Chain Alignment Procedures 5.5 Setting Optical Surround Delay Step No. Indication Action 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. Use the following formula to calculate the correct delay setting: 1.
5-33 B-Chain Alignment Procedures 5.5 Setting Optical Surround Delay Notes You can verify that the delay setting is acceptable by listening to a familiar Dolby encoded film which ideally contains both center channel dialogue and some discernible surround sound. The Dolby Cat. No. 251 SR/Digital “Jiffy” film serves excellently for this purpose. If a stereo film is not available, the delay time can be checked with a mono film, if the film is played in format 04 Dolby A-type.
5-34 B-Chain Alignment Procedures 5.6 Non-sync Level Adjustment Step No. Indication Action 47 Model CP45 48 60 Non-sync 1 49 Fader 4 5 6 3 7 2 8 1 9 0 10 fader active MONO MODE ENHANCE NORM NS1 MODE MATRIX NORMAL OUTPUT LEVELSURROUND DELAY SURR SUB 345 Cat. No. 511 Do lb y 789A E 6 +6.7V -6.
5-35 B-Chain Alignment Procedures 5.6 Non-sync Level Adjustment Notes Play a music cassette or CD on the non-sync device. If possible, select a recording that has a natural ambience such as an orchestral work. 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. Set the FADER to the 7 setting.
5-36 B-Chain Alignment Procedures 5.7 Final Check Step No. Action 45 04 Dolby Stereo A-type 46 JIFFY TEST FILM Cat. No. 251 SR•D—A subjective film for testing theatre sound RECORDED IN Running Time: 6 minutes Picture format: 1.85:1 widescreen or 2.35:1 anamorphic Sound formats: 10 05 digital analog Dolby Laboratories Inc.
5-37 B-Chain Alignment Procedures 5.7 Final Check Notes Press the format 04 Dolby Stereo A-type switch. Thread and play the Dolby Cat. No. 351 “listen . . .” film on the newly aligned system. 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.
6-1 SECTION 6 REFERENCE DIAGRAMS
A-1 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. Equally, the cell preamplifier gain could be increased, but this could cause unwanted hum and noise.
