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Dolby Laboratories CP65 manual Loudspeakers and Crossovers, a. Setting Room Equalization, Action

Models: CP65

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Page 41

Loudspeakers and Crossovers

5-4

B-Chain Alignment Procedures

a. Setting Room Equalization

Step	Action	Indication
No.

4

Cat. No.	Cat. No.
85	150

5

5-5

B-Chain Alignment Procedures

a. Setting Room Equalization

Notes

Remove the Cat. No. 150 Card. Note that when the Cat. No. 150 card is removed, two card edge connectors are exposed on the backplane and that another slot to the immediate left of the Cat. No. 150 slot is accessible. This second slot and associated connector are for the Cat. No. 85C Pink Noise Generator.

Install the Cat. No. 85C Pink Noise Generator in the special slot to the left of the Cat. No. 150 slot. The switches in the Cat. No. 85C are up or down for ON and center for OFF. The phase is positive when the switches are in the up position and negative in the down position.

Loudspeakers and Crossovers

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.

In systems with pairs of drivers — woofers or tweeters — one of the pair may be open but the system will still function. Check the speakers with an ohmmeter. If one channel requires markedly more equalization than the other or if one speaker overloads at lower levels than the other speakers, an open driver circuit could be the cause.

•Missing drivers or other components.

•The settings of the crossovers to match the type of drivers in use and the acoustics of the theater.

The tweeter level control must be set for the best possible frequency response with the Cat. No. 64 controls all at mid-point before you attempt any equalization. (The same procedures should be followed if the system uses active crossovers with bi-amp equipment.) This check should be made with a real time analyzer.

•Phasing between the woofers and tweeters, and between the channels (see Appendix A).

•Aiming of speakers.

Check that the speakers are correctly aimed into the auditorium, and that they are not obstructed by the screen frame, struts or other obstructions.

Image 41

Dolby Laboratories CP65 manual Loudspeakers and Crossovers, a. Setting Room Equalization, Action, Indication

Contents

Model CP65 Cinema Processor Installation and Alignment InstructionsU.K. European Office Dolby Laboratories Inc U.S. HeadquartersDolby Laboratories Inc 100 Potrero Avenue San Francisco, CA TelephoneINITIAL SET-UPAND INSTALLATION Table of ContentsINTRODUCTION EQUIPMENT REQUIREDAPPENDIX B APPENDIX AAPPENDIX C APPENDIX DCP65 INTRODUCTION04 Dolby Stereo A-type 05 Dolby Stereo SR 60 Non-syncPage 2 1kHz, 100% Modulation, Left/Right - Cat. No SECTION EQUIPMENT REQUIRED1 Dolby Tone and Pink Noise - Cat. No 3SMPTE Buzz Track TEST FILM4Stereo Optical Surround Level - Cat. No JIFFYSECTION INITIAL SET-UPAND INSTALLATION Voltage SettingAcceptable Voltage RangeCat. No J5 J6 J7 J8 Cat. No. 249, Power Supply ModuleCat. No. 242, B-ChainCard J3 IN Cat. No. 443, Control Logic CardStandard CP65 or CP65A CP65 BackplaneCP65-300 In a CP65-300when Cat. No. 300 modules are fitted in place of the normal Cat. No. 350 modules J16 and J18 should be rotated so that the words “Format 42” appears the right way up. With J24 in the “NR” position input signals will be A-typedecoded when the Mag/Aux format is selected. With J24 in the “NO NR” position signals pass through the noise reduction modules but the processing will be turned off. If both of these processing options are required frequently an external switch may be connected to J24J1 Optical Bass Extension output level sets the output level range for the subwoofer channel. In the HIGH position J1 is set at the factory for a power amplifier input sensitivity of between 90 mV and 1.23 V. If the power amplifiers used in the installation are very sensitive 10 mV to 100 mV input sensitivity, it may be necessary to set J1 to the LOW position. If you are unsure of the sensitivity of your power amplifiers set J1 to the LOW position initially. If the high output position is required this will be determined during OBE alignment Card Descriptions selected projector. Electronic switches selectSlot CardReduction Module Two-channelNoise2 4 Channel Decoder 7,8,9Card SlotFunction Cat. NoInternational Voltage SettingFuse TypeGB F D I E S NL IEC NOTICESIMPORTANT SAFETY NOTICE IMPORTANT - NOTE DE SECURITEModel CP65 HUM PROBLEMS3.Room lighting dimmer controls SCR-TYPE With CP65 FADER turned up and format 04 selected 2. Aligning the B-Chain SECTION AN OVERVIEW OF THE ALIGNMENT PROCEDURE1. Aligning the A-Chain and with a broad range of speakers. Accurate equalization requires the use of standardized acoustic measurement procedures Many loudspeakers used in theatres are far from ideal and require boosting of the low- and high-frequencyextremes in order to produce an approximation of the standard reference response curve. Bass and treble controls-centeredon the turnover points of typical loudspeakers-liftthe ends of the spectrum without the need for large amounts of narrow- band boost from the third-octavecontrols in the Cat. No. 64 cards. The third-octavecontrols are used for minor adjustments that are required to smooth the frequency response curve SECTION A-CHAINALIGNMENT a. Preliminary Procedures Notes a. Preliminary ProceduresAction Indicationa. Preliminary Procedures A-ChainAlignment Proceduresa. Preliminary Procedures Notes Actionb. Optical Preamplifier Adjustments Notes b. Optical Preamplifier AdjustmentsAction Indicationb. Optical Preamplifier Adjustments A-ChainAlignment Proceduresb. Optical Preamplifier Adjustments Notes ActionCAT NO L L R R L L R Rb. Optical Preamplifier Adjustments b. Optical Preamplifier Adjustments NotesIndicationn ActionCAT. NO. 97 TEST FILM REPEATRTA DISPLAY OSCILLOSCOPE TRACESA-ChainAlignment Procedures b. Optical Preamplifier AdjustmentsREPEAT 12 ANDA-ChainAlignment Procedures b. Optical Preamplifier AdjustmentsFOR PROJECTOR NO. REPEAT 1 → CAT NOb. Optical Preamplifier Adjustments b. Optical Preamplifier Adjustments NotesMagnetic Alignment c. Magnetic Preamplifier AdjustmentsMagnetic Alignment A-ChainAlignment Proceduresc. Magnetic Preamplifier Adjustments SECTION B-CHAINALIGNMENT a. Setting Room Equalization Notes a. Setting Room Equalizationbypass Actiona. Setting Room Equalization Loudspeakers and Crossoversa. Setting Room Equalization Notes ActionAmplifiers bypassGeneral a. Setting Room Equalizationa. Setting Room Equalization Notes B-ChainAlignment ProceduresAction Indicationa. Setting Room Equalization REPEATa. Setting Room Equalization Notes Actiona. Setting Room Equalization B-ChainAlignment Proceduresa. Setting Room Equalization Notes Actiona. Setting Room Equalization Do not adjusta. Setting Room Equalization Notes Actiona. Setting Room Equalization Notes a. Setting Room EqualizationAction Indicationb.Adjusting L,C,R Gain b. Adjusting L,C,R GainL 14 → 21 R 14 → 22REPEATc. Setting Mono Gain Notes c. Setting Mono Gain79 dBC Actiond. Subwoofer Alignment Cat. No. Notes d. Subwoofer Alignment Cat. NoB-ChainAlignment Procedures ActionB-ChainAlignment Procedures 90 dBCd. Subwoofer Alignment Cat. No Actiond. Subwoofer Alignment Cat. No FROMd. Subwoofer Alignment Cat. No Actiond. Subwoofer Alignment Cat. No Select format 04 Dolby Stereo A-TypeAction REPEATd. Subwoofer Alignment Cat. No SAME ASd. Subwoofer Alignment Cat. No Actione. Surround Equalization Alignment Cat. No Re Se. Surround Equalization Alignment Cat. No ActionAction e. Surround Equalization Alignment Cat. NoREPEAT e. Surround Equalization Alignment Cat. NoAction Action 88 dBCe. Surround Equalization Alignment Cat. No e. Surround Equalization Alignment Cat. No B-ChainAlignment ProceduresAction IndicationThumbwheel Switch f. Adjustment of Surround Delaymsec Settingg. Adjustment of Bypass Gain Notes g. Adjustment of Bypass Gainxx dBC B-ChainAlignment ProceduresB-ChainAlignment Procedures FROM xx dBC -3dB yy dBCg. Adjustment of Bypass Gain g. Adjustment of Bypass Gain Notesh. Adjustment of Non-syncGain Notes h. Adjustment of Non-syncGainPress the format 60 non sync switch Actionh. Adjustment of Non-syncGain Notes h. Adjustment of Non-syncGainAction Indicationi.Adjustment of Mono Gain and Equalization Notes i. Adjustment of Mono Gain and Equalization5REPEAT PAGE 5-20STEP B-ChainAlignment ProceduresJIFFY TEST FILM Press the format 04 Dolby Stereo A-type switchj. Final Checks j. Final Checks NotesSECTION REFERENCE DIAGRAMS Cat. No. 222 Dual Noise Reduction Module OUTPUTS INPUTSPage Cat. No. 242 B-ChainFacilities Card Cat. No. 249 Power Supply Card Cat. No. 259 Transformer Module OUTPUTS INPUTSCat. No. 443 Control Logic Card Cat. No CP65 POWER DISTRIBUTION TABLE+24V +15VAPPENDIX A CHECKING PHASING OF SPEAKERS 5,000 Frequency in Hz10,000 20,0002.Cat. No. 327A Circuit Description APPENDIX C CP65M MONO INSTRUCTIONS1.Operation A3C2984 rev C.2 Schematic Cat. No. 327ACP65 Backplane Connections APPENDIX D BACKPLANE CONNECTIONS LISTTerminal Block TB1 Terminal Block TB2D connector J18