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JBL CINEMA SOUND SYSTEM MANUAL

Table of Contents

I. INTRODUCTION.. ..................................................................................................
II. BASIC SYSTEM CONCEPTS.. ..............................................................................

A. Analog Film Formats.. ................................................................................

B. Digital Film Formats ...................................................................................
C. A- and B-chains .........................................................................................
D. Evolving Dynamic Range Requirements in the Cinema.. ...........................

E. Integration of Loudspeakers into the Acoustical Environment..................... 7
F. Power Response and Power-Flat Systems ................................................

G. Coverage Requirements for Proper Stereo Reproduction

III. ACOUSTICAL CONSIDERATIONS ......................................................................

A. Noise Criterion (NC) Requirements.. ..........................................................

B. Control of Reverberation and Discrete Reflections ....................................

C. The Role of the Acoustical Consultant.. .....................................................

IV. SPECIFYING THE CORRECT LOUDSPEAKERS AND AMPLIFIERS.. ...............

A. Hardware Class vs. Room Size.. ................................................................

B. Advantages of Biamplification .....................................................................

17

C. Cinema Playback Level Calibration.. ..........................................................
D. New JBL Driver Developments ..................................................................

E. Mechanical Details of JBL Screen Loudspeaker Systems .........................
F. Subwoofers ................................................................................................
G. Surround Requirements.. ...........................................................................
H. Screen Losses.. .........................................................................................
I. Use of Multiple High Frequency Elements.. .................................................

V. MOUNTING REQUIREMENTS.. ............................................................................

A. General Comments .....................................................................................

31

B. Platform and Baffle Construction.. ..............................................................
C. Subwoofer Mounting.. ...............................................................................
D

Surround Mounting ...................................................................................

VI. ELECTRICAL INTERFACE ..................................................................................

A. Wiring for Non-biamplified Installations.. ...................................................

B. Wiring Diagram for a Biamplified Installation.. ............................................
C. Wiring for Surround Channels.. ..................................................................
D. Wire Gauges and Line Loss Calculations ..................................................
E. Dividing Network Characteristics.. ..............................................................
F. System Setup and Checkout.. ....................................................................

References.. ...............................................................................................................

 

Содержание CINEMA SOUND SET UP

Страница 1: ...C I N E M A S O U N D S Y S T E M M A N U A L January 1998...

Страница 2: ...RRECT LOUDSPEAKERS AND AMPLIFIERS 15 A Hardware Class vs Room Size 15 B Advantages of Biamplification 17 C Cinema Playback Level Calibration 17 D New JBL Driver Developments 18 E Mechanical Details of...

Страница 3: ...spaces More attention is being paid to the specification of sound equipment and its careful integration into the cinema environment JBL has a strong commitment to the cinema sound market We have beco...

Страница 4: ...a single surround channel At the same time the standard monophonic variable area optical track was maintained Figures IA and B show the channel layout for both 70 mm and 35 mm magnetic standards At p...

Страница 5: ...relationship triggers the playback matrix to steer that information primarily to the surround loudspeaker array Figure 2B shows details of the playback matrix used in Dolby Stereo Optical soundtracks...

Страница 6: ...ny as 5 screen channels for special applications All digital formats discussed here have a fall back failsafe mode in which the analog tracks will be used in case of failure of the digital portion of...

Страница 7: ...DUCTION LAMP i Figure 4A Block diagram of analog A chain SIGNAL OUT Figure 48 Block diagram of digital A chain SCREEN CHANNEL I1 of31 MASTER FADER pg SURROUND CHANNEL il Of 2 A 1 3 OCTAVE _ EO SUB CHA...

Страница 8: ...in this manual will meet these new specifications consistent with the size of the cinema for which the systems will be specified dE 110 100 SO 80 1 375 63 125 253 500 1K 2K r 8K 16K tiz Peak power lev...

Страница 9: ...on axis response of the system may be fairly flat when measured under non reflective conditions A Off axis response of ported horn system C Reverberant power response of a cinema system composed of e...

Страница 10: ...requency driver which has been equalized for flat power response Note that the off axis curves are essentially parallel indicating that the horn produces a solid radiation angle which is uniform with...

Страница 11: ...es strict limitations on where the listener must sit in order to perceive correct stereo imaging The factor that makes the big difference in the cinema is the presence of the center channel Not only d...

Страница 12: ...erformance is seen in Figure 8 At A we show in plan view the direct field coverage given by a JBL 2360 horn aimed at the absorptive back wall of a large theater with sloped floor Coverage at 2 kHz is...

Страница 13: ...orked out that the effects intended by the sound mixer can be appreciated by the viewing audience III ACOUSTlCAL CONSIDERATIONS A Noise Criterion NC Requirements The usual sources of noise in a cinema...

Страница 14: ...irm scientific ground in these matters Typical standard STC curves are shown in Figure 10 The isolation task is certainly easier with new construction since buffer areas can be designed between adjace...

Страница 15: ...as such will be beneficial Discrete reflections are likely to be a problem only if they clearly are displaced from the direct sound in both time and spatial orientation Side wall reflections are usual...

Страница 16: ...en the two sections 3 lmoact and structure borne noise These are some of the most difficult problems to fix since they are literally built in Plumbing noises elevator motors and air handling machinery...

Страница 17: ...300 800W 5o ooo cu ft 2700m3 108 111 500 800W 100 ooo cu R 5400m3 104 109 loo0 800W 200 ooo al ft Table 1A Maximum Reverbwant Levels1 for JBL 467OD and 467 Systems in Cinsmas of various sizes non b m...

Страница 18: ...85 dB SPL in the house when the modulation on the tape is so called zero level or 185 nanowebers meter This last quantity has to do with Mording technology and we need not concern ourselves with it f...

Страница 19: ...nse of the dual low frequency 4638 system which incorporates two of the 2035 transducers ml20 xl im 200 5m 1 000 2 03l 5 m ro om 2o clm REQUEW WJ On axis response of dual 360 mm 15 in 4636TH LF system...

Страница 20: ...I I lrn Y 17s r FQure 14 Complete system assembly diagram for 46700 and 46756...

Страница 21: ...PLODED VIEW Driver Hiih F req 2446t t Gasket 20810 Bracket Inner Driver Horn n Sale Binding Post Red 33750 Blk 33751 screw 2 No 8xV2 FWHD PH BLK I Bracket Outer Mounting Base 72109 Not For Sale Assemb...

Страница 22: ...PLODED VIEW Horn 2370A 6486641 Network 3llOA Fwyf fz t bhft3 Instattation Kit 55343 Port Tube 57932 Not For Sale Gasket Vinyl 34499 Use Mounting Hardwar IfIchled With In tion Kit 55340 Cabinet 4507 63...

Страница 23: ...ept D18R2448 tJMyJ fif Hardware Installation Kit 57538 support 2508 80851 Use Mounting Hardware Included With Unit Network 3115A 47031 lose Mounting Hardware Included With Installation Kit 55343 Gaske...

Страница 24: ...DED Gasket 60718 01 JBL4675GHF VIEW Drhw Hiih Fmq 2446H Bolt 4 114 20x l 111 Hom236OA 60703 01 Washer Bon 6 l 4 20 x 2 114 Bindin Post EzY Et Adapter 60705 Bracket Assy 25068 And Mounting Hardware 721...

Страница 25: ...gure 19 ZOMPONENT EXPLODED Scmw 4 EE6xW PHLRGHDhlSSLK g Port Tube 2 56144 Not For Sale Gasket 2 34499 Sg er Low Freq 2 Cone Rep1 Inseri Threaded 16 63154 01 10 32x l 2 screw 6 56460 No 6x3l4 FLHD PH E...

Страница 26: ...iagram 4671 B wiring diagram FROM 0 AMPLIFIER HF DRIVER LF SPWER INPUT jED 2 46738 wiring diagram 4675C wiring diagram 2mH LFSPEAKER FRcA4 AMPLIFIER t RED BLACK f lF bb HF 00 RED EIACK BLACK RED 0 0 0...

Страница 27: ...Hz Figure 21 Robinson Dadson equal loudness contours Since low frequencies are essentially nondirectional we commonly specify subwoofer U hardware by calculating the acoustical power requirements in...

Страница 28: ...exploded view of the JBL 46458 subwoofer module Each subwoofer module should be driven with its own amplifier capable of producing up to 800 continuous watts of sine wave power into a rated impedance...

Страница 29: ...OMPONENT EXPLODED VIEW Port Tube Not For Sate I JBL 4645B winat 60669 01 P Screw 65555 Speaker Low Freq 2242HPL...

Страница 30: ...oviding smooth coverage over the seating area Generally four of the units are placed on the back wall and four each on the side walls Good surround operation depends on a significant quantity of insig...

Страница 31: ...mid frequency program and enables patrons seated to the sides to enjoy good dialog intelligibility With the newer high frequency hardware the overall required system equalization is substantially the...

Страница 32: ...ce V MOUNTING REQUIREMENTS A General Comments The following rules generally appfy to screen loudspeakers 1 2 3 4 5 They should be located vertically so that the horns are between one half and two thir...

Страница 33: ...is will require that the left and right screen loudspeakers be toed in regardless of screen curvature This will ensure that proper stereo imaging will be perceived by those patrons seated toward the s...

Страница 34: ...sponse switch on the 8330 and 8340 surrounds should be placed in theIS0 2969 X curve position for cinema application Figure 27 shows details of surround mounting and Figure 28 shows an exploded view o...

Страница 35: ...ED Screw 8 762 61 CM 75 No 6 x 3I4 FLHD 100 BLK Horn Driver 127 10000 00 JBL8340 IEWO Not For Sale Speaker Low Freq 124 21000 00 screw 4 67375 No 8 x l 114 FLHD PH BLK NO 8 x 1 PNHD PH BLK T Nut 8 z s...

Страница 36: ...eature such as the IM 12 module that is included in the Open Input Architecture options available for JBL s MPA series power amplifiers FROM CPU c RED HI I I RED I I BL s BL ____ 5235 LO RED 1 STEREO...

Страница 37: ...o six loudspeakerswired in sefieslparallel Figure 30 Typical passive network cinema system 8330or8340smnmdlodswkerstypiceloftwosets of four to six budspeakers wired in seri ralld Figwe 3 1 Typical bia...

Страница 38: ...e booth For each 6340 100 to 150 watts should be allocated Thus for the 5 3 ohm per side configuration a single model MPX1200 will be appropriate with each side feeding a 5 3 ohm load and delivering a...

Страница 39: ...ANWlRE GAUGE RESISTANCE PER SlW XE RUN b m IAWG 300 METERS K OO OF COPPER 6 00 6 00 2 50 2 50 1 50 1 50 1 00 1 00 75 75 so t 0 1 2 1 6 2 0 2 5 3 2 4 0 5 0 6 3 8 0 10 0 NOTE Paralleling two identical A...

Страница 40: ...ower reqonse correction for 236OA Series horns 8 500HzlEd withpcmnreeponcleanreQionfor238044 S3ries hams Figure 34 Tvpical HF and LF response curves for active frequency dividing networks F System Set...

Страница 41: ...e that the widest possible dynamic range is preserved through the chain No electronic device ahead of the power amplifier should be driven into distortion before the power amplifier itself has reached...

Страница 42: ...Acoustical Background Noise Levels in Dubbing Stages EG14 1987 I Allen Technical Guidelines for Dolby Stereo Theatres Dolby Laboratories September 1992 6 T Holman THX Sound System Instruction Manual A...

Страница 43: ...JBL Professional 8500 Balboa Boulevard Northridge California 91329 USA H A Harman InternatoM Company Copyright 1998 JBL Professional Printed in USA...

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