JBL Motion Picture Loudspeaker Systems User manual

InstructionManual
A.Introduction:
Althoughthecompany'srootsextendback
totheearlydaysofmotionpicturesound,it
hasonlybeeninthelastfewyearsthatJBL
hasmadea significantimpactonthecommercial
theatermarket.Someofthereasonsforthisare
thecompany'spreeminenceinhigh-qualitysound
reinforcementingeneralandthedevelopmentof
thenotionofflatpowerresponseinparticular.
Injustthelastyear,JBLtheatersystemshave
beenincorporatedintosomeofthemostpresti-
geousdubbingtheatersandscreeningroomsin
thefilmindustry.Wenowfeelthatthetimeis
righttopreparea comprehensiveapplications
manualforourtheaterdealerstoaidthemin
systemdesignandspecificationandtogivethem
anedgeovertheircompetitors.
B.SystemsforSmallerHouses:
1. A summaryofhousetypes:
Byfar,mostofthetheatersbeingbuilt
todayarelongrectangularrooms.Theyare
usuallybuiltingroupscalledmultiplex
theatersforreasonsofeconomy.Mostof
thesetheatersaremono,witha single
loudspeakerbehindthescreen,andthe
seatingcapacityusuallyrangesfrom200
to500.Ingeneral,thelargerhouses,those
seating1000ormore,werebuiltsomeyears
ago, andtheseareusuallyequippedwith
threeorfiveloudspeakersbehindthescreen
andwillhavea multi-speakersurround
channellocatedontherearandsidewalls.
Averyfewhouses,usuallyfoundonlyin
largercities,willhavespecialeffects
low-frequencychannels,suchasSensurround,
forspecialscreeningsofimportantfilms.
MotionPicture
LoudspeakerSystems
2. GeneralAcousticalCharacteristics:
Historically,motionpicturetheaters,
whatevertheirsize,havebeenacoustically
"dead" rooms;thatis,theyhaveconsider-
ableabsorptionontheboundaries,andrever-
berationtimes,eveninthelargerhouses,
rarelyexceed1.25seconds.Morelikely,we
willfindthereverberationtimesinsmaller
housestobeinthe0.5secondrange.The
reasonforthisofcoursehastodowith arti-
culationandclarityofdialog.
Themostcommonmethodoftreatingthe
interioroftheatersiswithvelourdraping.
Thisisaninteriortreatmentonly;structurally,
thearchitectreliesonsolidblockwallsto
minimizesoundleakagefromadjacenttheaters.
Oneofthemostcommonproblemsencoun-
teredintheatersisa slaporreflectionoff
theback wall, whichoftengoesuntreated.
Shouldthebackwallbecurved,thenthe
effectmaybeevenworse,duetofocussingof
thereflectionbacktothefront.
3.SoundLevelRequirements:
Averagepeaklevelsof85dB-SPLarecommon
inthetheater.A minimumheadroomfigure
abovethiswouldbe10dB,butJBLrecommends
15dBfora greatermeasureofsafety.The
followingfactorsaretakenintoconsideration
indeterminingthekindofsystemtospecify
andtheamountofamplifierpowerwhichwill
berequired:
a. Roomvolume
b.Roomboundaryarea
c.Reverberationtime
d. Systemsensitivityandpower
rating
e.Systemdirectivityindex

TableI presentsJBL'ssystemrecommenda-
tionsbasedongeneralassumptionsregarding
roomratiosandreverberationtimes.Allthe
theaterdealerorcontractorhastodois
calculatetheroomvolumeandgotothatentry
inthetable.Themid-houselevelsarethose
calculatedbyassumingthatthereverberant
soundinthetheaterandthedirectsoundfrom
theloudspeakersareequal.Beyondthatpoint,
thesoundlevelwilldropoffsomewhat,while
infrontofthatpointthesoundwillbelouder.
DetailsofthevariousJBLsystemsrecom-
mendedforsinglechanneluseinmultiplex
theatersaregiveninFigure1.Thechoice
betweenseveralsystems,allofwhichmight
meetthespecification,mustbebasedona num-
berofconsiderations.Ingeneral,themodels
4672Aand4674Awillresultinlessamplifier
powerrequirement;however,thesesystemsbegin
torolloffbelow120Hz,whilethemodels4671
and4673extendsmoothlydownto45Hz.Another
considerationisenclosuredepth.Thespacebe-
hindsomescreenscanbeassmallas0.6meter
(2feet),andthisoftendictatessystemchoice.
4. SystemInstallation:
Wheneverpossible,thescreenloudspeaker
shouldbelocatedone-thirdthewayupthescreen.
Shouldthescreenitselfbehigherthanusual,
requiringpatronsseatedtowardthefrontofthe
housetolookupward,thentheloudspeakermay
beplacedsomewhatlower.Asa rule,the loud-
speakerhigh-frequencyelementshouldbeaimed
towardthefarthestseats.Thisiscertainlythe
waytogoifthebackwallisdraped.Ifit
cannotbedraped,thentiltingthesystemdown
abitmayhelp.Thesystemshouldbeplacedas
closeas0.3meter (1 foot)tothescreento
minimizetheeffectofhigh-frequencysound
reflectingbetweenthescreenandthewallbe-
hindtheloudspeaker.Ifpossible,thewallarea
behindthescreenshouldbetreatedwithsound
absorptivematerial.SeeFigure2 fordetailsof
this.
Mostofthewirerunsina theaterwillbe
shortenoughsothata wiregaugenogreater
thanAWG#12willberequired.AllJBLtheater
systemsshouldbeconsideredas8-ohmsystems
inmakinglinelosscalculations,andthegeneral
ruleisthatlinelossesshouldbeheldtono
greaterthan0.5dB.TableIIshowslinelosses
forvariousrunsandgauges.
Thetheaterdealershouldalwaystrytospeci-
fya stereoamplifierwhichcanbebridgedfor
monooperation.Caremustbetakenthatthe
amplifier'sbridgedmonoratinginto8 ohmswill
notbeexceeded.
C.SystemsforLargerHouses:
1. Choosingthesystem:
Figure3 showstheJBLsystemsnormally
specifiedformulti-channeluseintheaters.
NotethatthesesystemsallmakeuseofBi-Radial
high-frequencyhorns.Themodels4675and
4676A-1makeuseofthe236090-by-40degree
hornfornormalcoverage,whilethe4676A-2
usesa pairof236560-by-40hornssplayedfor
90-degreecoverage.
Ofthesethreesystems,the4675willbethe
mostusefulbecauseitexhibitsthesmoothest
powerresponseofanysystemthatJBLmakes.
Thisis,infact,theonethathasbecomewell
knowninfilmproductioncirclesas"JBL'snew
theatersystem."
TableIIIwillenablethetheaterdealerto
specifyandchoosepowerforthesesystemsin
largertheaters.Thepowersgivenforeach loud-
speakerenableeachchanneltoreacha levelof
100dBinthehouse.Dependingontheexactna-
tureofthemulti-channelinstallation,the
behind-the-screenresourcesmaybefive full-
rangechannels,orthreefull-rangechannelsand
twolow-frequencyaugmentationchannels.
2. Poweringthesystem:
Withtheselargersystems,wehavetheoption
ofbiamplification.Whilethisismoreexpensive
thanthenormalsingleamplifierapproach,itdoes
resultinfarcleanersoundonpeaksbymakingit
impossibleforlow-frequencysignalstomodulate
high-frequencysignals.Figure4 showsthetwo
waysthattheselargersystemscanbeimple-
mentedelectrically.
Biamplificationallowsconsiderablymore
powertobedeliveredtotheLFportionsoftheater
systems,sincethepassivedividingnetworkis
beingbypassed.Biamplificationshouldcertainly
beconsideredessentialifthetheaterinstallation
isintendedforplaybackatlevelsinexcessof
100dB.
3.Installationofthesystem:
Aswestatedearlier,itiscustomaryfor
screenloudspeakerstobelocatedabout
one-thirdthewayupthescreenandasclose
as0.3meter (1 foot).Thecenterloudspeaker
shouldbenormaltothescreen,buttheflank-
ingloudspeakersmaybetoedinslightly,as
showninFigure5,inordertoensureeven
coverage,andconsequentlybetterstereo,for
thosepatronsseatedofftooneside.

D.SurroundChannels:
1=Genera!requirements:
Whilethereislittleconsistentpracticein
specifyingandimplementingsurroundchannels,
wecanlaydownthefollowingrequirements:
a. Thetotalacousticalpowerdelivered
bytheensembleofsurround loud-
speakersshouldbeequaltooneof
thescreenchannels.Therearepro-
bablynotmanysurroundchannels
whichmeetthisrequirement,but
itisessentialifthefullimpact
ofsurroundinformationistobe
appreciated.Whilea 15-dBheadroom
factorisa partofthepowercalcu-
lationsforthescreenchannels,it
maybeunreasonabletodemandthat
ofthesurroundchannel.Thus,a
requirementthatthesurroundchannel
beabletoproducea levelinthe
houseof95dB-SPLwillsuffice.In
thecaseofthedistributed200mm
(8")speakersystem,a levelof
92dBisdeemedsufficient.
b.Thequantityofsurroundloudspeakers
shouldbesufficientsothatlisteners
arenotawareofonlyoneofthem.
Thisusuallymeansa minimumof
eight:threeeachonthesidewalls
andtwoontheback wall.
c.Thesurroundloudspeakersshould
exhibitwidedispersionsothatthe
entireaudienceareacanappreciate
evencoverageacrossthefrequency
range.
d. Surroundloudspeakersshouldbe
unobtrusiveandnotinterferewith
theaterdecor.Thisrequirementmay
runcountertosomeoftheacoustical
requirementsinthatsizeisrelated
tosystemefficiency.
TheJBL4401monitorloudspeakerworks
extremelywellsincea smallnumberofthem,
usuallylesstham12,willprovidethedesired
levelinmanyhouses.TheMC4401mounting
cradleprovidesa convenientmethodof wall-
mountingandanglingthe4401system.TableIV
presentsdetailsofsurroundloudspeaker
selection.
Theuseofmultiple200mm(8")loudspeakers
hasbeenfavoredbyDolbyLaboratories.Whilethe
hardwarecostsmaybereasonable,thelaborcosts
forthisapproachareaccordinglyhigher.Forthis
typeofsystem,theJBL8140co-motionaltrans-
ducerwillbea logicalchoice.Thebafflesused
insuchaninstallationshouldideallybe con-
structedaccordingtothetransducermanufac-
turer'splansorrecommendationssothatlow-
frequencyresponsewillbeadequate.A lowercost
approachcallsforusingoneofthemanystandard
tiltedfrontenclosures.Asa rule,thesearetoo
smallinvolumeforproperlow-frequencyresponse,
andtheclientshouldunderstandthisattheoutset.
The4671theatersystemisrecommendedfor
high-powersurrounduse.Withanefficiencyof
3.5%,relativelyfewoftheseunitsarerequired.
Theywouldnormallybespecifiedwhentheentire
theaterreproductionsystemwascalleduponto
producelevelsinthe105-to-110-dBrange.
2. Poweringthesurroundchannel:
Figure6 presentsdetailsoftheimplementa-
tionofthesurroundchannel.AtC throughE,we
showdetailsoftheelectricaldistribution.Depen-
dingonthenumberofsurroundloudspeakers,the
hook-upwillbeseries-parallel,andtheresulting
impedancecanusuallybeheldtonolessthan4
ohms. Anamplifiershouldbechosenwhose4-ohm
powerratingwillnotbeexceeded.Insomecases,
theJBLmodel9375linematchingautotransformer
willbeusefulinmaintainingthedesiredim-
pedance.Forthe200mm(8")loudspeakers,a
70-voltdistributionsystemshouldbeused.See
JBLTechnicalNote,Volume1,Number2,for
detailsofthismethod.
E.SubwooferSystems:
1. Background:
Universal'sintroductionof"Sensurround"
duringtheseventiesbroughtspecialeffectsvery-
low-frequencychannelsintothemotionpicture
theater.Typically,thesechannelscovertherange
from20-25Hzupto40-50Hz.Quitehighacoustical
poweroutputisrequired,sincetheearisrelatively
insensitivetoextremelylowfrequencies.
2. Implementation:
Mostinstallationsofsubwoofersaredictated
bytherequirementsofparticularscreenings,and
instructionswillgenerallycomefromthestudios
orthroughthefilmdistributors.TheDolbymodel
CP200processorprovidesa low-frequencyoutput
thatmaybeusedtodrivea subwooferchannel
directly.
TableV presentsdataonselectingthe
numberofsubwoofermodulesneededforparti-
cularsoundlevelsintheatersofdifferent
volumes.Theenclosurerecommendedhereisthe
4518. Itsspecificationswiththe2245HLFdriver
aredetailedincolumn4 ofJBLTechnicalNote,
Volume1,Number1.Itisimportanttoprovide
adequateandstablepowerforpropersubwoofer
operation. Wheneverpossible,theamplifiers
shouldbelocatedattheloudspeakersthemselves.
Notethatasthenumberofmodulesis
doubled, thesoundpressureincreases6 dB.
ThreedBareduetothedoublingofpower

handling, andtheremainingthreecomefrom
mutualcoupling,thetendencyoftwoloudspeakers
tobehaveasa single,moreefficientloudspeaker.
F.AcousticalResponse:
1. Conceptofflatpowerresponse:
toshipthecomponentscompletesothatthe
systemscanbereadilyassembled.Itisa wise
dealer,however,whowillkeepa goodstockof
replacementcomponentsandmountinghardware.
Thesystemsdonottravelwellintheirassem-
bledform,sotheyshouldalwaysbeassembledat
theirfinalsite.Alltransducersshouldbechecked
priortobeingsentout,however.
Whilemostloudspeakersystemsarefairly
flatonaxis,theytendtonarrowconsiderablyin
theircoverageanglesathighfrequencies.Their
powerresponseissaidtorolloff.Ifa loud-
speakermaintainsfairlyconstanthorizontaland
verticalcoverageanglesovermostofitsfre-
quencyrange,thenflaton-axisresponsewillalso
implyflatpowerresponse.Sinceabouthalfofthe
soundheardinthetheaterhasbeenreflectedat
leastonce,itisimportantthatloudspeakers
exhibitfairlyflatpowerresponseifthereproduced
soundistobenatural.
Anotherconsequenceofusingloudspeakers
withflatpowerresponseisthatlittlesystemequal-
izationisrequired.Figure7 illustratesthis.At
A,weseetheboundaryabsorptionina typical
well-designedtheater.Notethatitisquiteflat
overthefrequencyrange.High-frequencylosses
duetoairabsorptionareshownatB,andtypical
high-frequencyscreenlossesareshownatC.
Whenweaddupallofthese,wegettheresponse
shownatD,andthisisexactlytheacoustical
responsewewouldobserveintheroomifwe
wereusinga loudspeakerthathadflatpower
response.
Figure8 showsthestandard"housecurve"
towhichmosttheatersystemsareequalized.
Notethatitcloselyresemblesthesummed
curveshowninFigure7,D,indicatingthatflat
powerresponsesystemswillrequirelittle,ifany
addedequalizationinmosthouses.
JBL'stheatersystemsusingBi-Radialhorns
exhibitessentiallyflatpowerresponseaswell
asflaton-axisresponse.Thesmallersystems
exhibitflaton-axisresponse,buttheirpower
responserollsoffslightlyathighfrequencies.
JBL'spassivedividingnetworksprovidefora
high-frequencyboostwhicheffectivelymakesany
ofthesystemspower-flatathighfrequencies.
Inthesmallersystems,thismaybeaccompanied
bya slighton-axisriseathighfrequencies.
Nevertheless,werecommendthatthehigh-
frequencyboostbeusedinalltheaterapplica-
tions.
H.SystemAssembly:
2. Detailsofassembly:
WepresentinFigure9 detailedwiring dia-
gramsofeachofthetheatersystems,alongwith
acompletelistingofcomponentsineachsystem.
Figure10showsdetailsofmountingLFtrans-
ducersinthevarious4500-seriesLFenclosures.
Themodels4507,4508and4518allrequirefront-
mountingoftransducers.ThereareT-nuts
mountedonthebacksideofthebaffle,andthe
fourmountingscrewsforeachtransducerengage
theseasshownatA.
Boththe4550BKAand4560BKAhave
demountablebackpanels.Theseareremovedand
theLFtransducersmountedinplacewithscrews
engagingT-nuts,asshownatB.
High-frequencyhornsaremountedasshown
inFigure11.The2370horn-2425HFdrivercom-
binationisplaceddirectlyontopofthe4507LF
enclosure,anditsmouthisparallelwiththefront
oftheLFenclosure.Itshouldbemountedflush
withthefrontoftheLFenclosure.Twoangleirons
maybeusedtosecurethefrontofthehorntothe
enclosure,asshownatA.Analternatewayto
mountthesmallerBi-Radialhorns(2370and2380)
istoscrewthebottomfrontflangeintotheupper
frontedgeoftheLFenclosure,asshowninFigure
11C. TheusershouldnoteingeneralthatBi-Radial
horns, becauseoftheirextendedverticalcoverage
athighfrequencies,donotnormallyhavetobe
tiltedwithrespecttotheLFenclosureinorderto
providepropercoverageoftheaudiencearea.
Whenthe4560BKAenclosureisused,the
2370hornismountedina spaceprovidedatthe
topoftheLFenclosure.Theupperpanelis
removed, andthehornisscrewedintoplace,as
shownatB.
The2380hornismountedontopoftheLF
enclosureinthe4670A,4673,and4674Asystems.
Withthe2445HFdriverinplace,thehorn-driver
combinationsitsontopoftheenclosurewithits
mouthparalleltothefrontoftheenclosure.As
inthecaseshownatA,thefrontofthehorn
shouldbesecuredtotheenclosuretopwithangle
irons, orbyscrewingintothefrontedgeoftheLF
enclosure.
1. Generalcomments:
JBL'stheatersystemsareshippedtothe
dealerincomponentform.Everyattemptismade

TheBi-Radialhornsrequirethemodel2506
mountingbracketforproperinstallation.Proper
mountingisshownatbracketforproperinstalla-
tion. PropermountingisshownatD.Thebottom
ofthemouthoftheBi-Radialhornshouldbeflush
withthefrontoftheLFenclosure,andthemount-
ingbracketshouldbesecurelyscrewedtothetop
oftheenclosure.
Figure12showshownetworksaremounted.
Thesmallernetworks,models 311OA and3115A,
aremountedincut-outsintherearoftheLF
enclosures,asshownatA.Thehigh-power3152A
isscrewedontothebackoftheenclosure,as
shownatB.
4671 4673 4670A 4672A 4674A
PMAX=
150W PMAX=
150W PMAX= 300W PMAX=
150W PMAX= 150W
SENSITIVITY:
97dB,
1W,1 M
SENSITIVITY:
97dB,
1W,1 M
SENSITIVITY:
100dB,
1W,1 M,
SENSITIVITY:
103dB,
1W,1 M
SENSITIVITY:
103dB
1W,1 M
EFFICIENCY:
3.5% EFFICIENCY:
3.5% EFFICIENCY: 7% EFFICIENCY: 6.4% EFFICIENCY:
6.4%
FIGURE1.JBLSYSTEMSFORSMALLERTHEATERS
TABLEI.SYSTEMSANDPOWER
RECOMMENDATIONS
FORSMALLERHOUSES
SEATS VOLUME
(APPROX.) SYSTEMS POWERREQUIRED
FOR100dB RECOMMENDED
AMPLIFIERPOWER
200 1700M3
(60,000FT3) 4671
4673
4672A
4674A
46WATTS
46WATTS
23WATTS
23 WATTS
100WATTS
100WATTS
50WATTS
50WATTS
350 2832M3
(100,000
FT3)
4670A
4672A
4674A
30WATTS
30WATTS
30WATTS
50WATTS
50WATTS
50WATTS
500 4530M3
(160,000
FT3)
4670A
4674A 50WATTS
50WATTS 100WATTS
100WATTS
ABSORPTIVE
MATERIAL
2/3
V3
SCREEN
FIGURE2. SCREEN
MOUNTINGOF
LOUDSPEAKER

4675 4G76A-, 4676A-2
PMAX=
300W PMAX=
300W PMAX=
300W
SENSITIVITY:
100dB,
1W,1 M
SENSITIVITY:
106dB,
1W,1 M
SENSITIVITY:
109dB,
1W,1 M
EFFICIENCY:
7% EFFICIENCY:
8% EFFICIENCY:
16%
FIGURE3.JBLTHEATERSYSTEMSFORLARGERHOUSES
TABLEII.WIRELOSSES
WIRERUN(DOUBLE;COPPER)
NO. 10 NO.12 NO.14 NO.16
NO. 18
10M(33') .02 .032 .05 .08 .125
20M (66') .04 .064 .10 .16 .250
30M(100') .06 .096 .15 .24 .375
40M(132') .08 .128 .20 .32 .500
50M(165') .1 .160 .25 .40 .625
60M(200') .12 .192 .30 .48 .750
FOR8HLOAD,LINERESISTANCESHOULDBE 0.552 ORLESS.
TABLEIII.SYSTEMSANDPOWER
REQUIREMENTSFOR
LARGERHOUSES
SEATS VOLUME
(APPROX.) SYSTEMS POWERREQUIRED FOR100dB
RECOMMENDED
AMPLIFIERPOWER
PERLOUDSPEAKER
500-
8500M3 4675 72WATTS 150WATTS
1000 (300,000 FT3) 4676A-1 63 WATTS 125WATTS
14,160M3 M676A-2 42WATTS 100WATTS
1000-
14,160M3 4675 90WATTS 200WATTS
2000 (500,000FT3) 4676A-1 79WATTS 200WATTS
M676A-2 53 WATTS 125WATTS
BECAUSEOFTHEIREXTREMELYHIGHPOWERRATINGS,
THESESYSTEMSWOULDBESPECIFIEDWITHMUCHLARGER
POWERAMPLIFIERSTHANSUGGESTEDHEREFORUSEIN
SPECIAL,HIGHSOUNDLEVELAPPLICATIONS.

AMPLIFIER
HF
NETWORK
HFAMPLIFIER
LFOUT
LF
k
FULL-RANGEAMPLIFICATION BIAMPLIFICATION
*500Hz,POWERRESPONSE
CORRECTEDCARDTOBEUSED
FIGURE4.FULL-RANGEAMPLIFICATIONANDBIAMPLIFICATION
TABLEIV.SURROUNDSYSTEMDATA
SEATS 4401MONITOR 8140DISTRIBUTED
SYSTEM 4671
500-
8UNITS 30UNITS@ 6UNITS@
1000 @50WATTS 5WATTS 100WATTS
EACH
EACH* EACH**
1000-
12UNITS@ 38UNITS@ 10UNITS®
2000 50WATTS 5WATTS 100WATTS
EACH
EACH* EACH**
*FORA MAXIMUMLEVELOF92dB
'*FORA MAXIMUMLEVELOF107dB
BOTH4401AND8140SURROUNDSYSTEMSSHOULD
BEHIGH-PASSEDAT40HzORHIGHER.
TABLEV.SUBWOOFERSELECTIONDATA
NUMBEROFMODULES EFFICIENCY ELECTRICAL
POWERINPUT ACOUSTIC
POWER
SOUNDLEVELS
500- 1000-
1000SEATS2000SEATS
1
2%
300WATTS 6WATTS 101dB 100dB
2
4%
600WATTS 24WATTS 107dB 106dB
4 8% 1200WATTS 96WATTS 113dB 112dB
8
16%
2400WATTS 384WATTS 119dB 118dB

/ / \ / \ \
FIGURE5.POSITIONINGLOUDSPEAKERSBEHINDTHESCREEN
2/3
• • • •
T
1/3
ir
1
— .
A.SIDEVIEW
~• L_JCT™
]
]
mi—II—i
B.TOPVIEW
FIGURE6.SURROUNDSYSTEMIMPLEMENTATION

FIGURE6,CONT'D.ELECTRICALCONSIDERATIONS
70-VOLTOUTPUT
OFAMPLIFIER
(MAKESUREAMPLIFIER
HASADEQUATE
POWEROUTPUT) 200MM(8")LOUDSPEAKERSUSEDINMULTIPLE,
70-VOLTCONFIGURATION
JBL9315HT
*EACHLOUDSPEAKER
TAPPEDAT5 WATTS
FIGURE6,CONT'D.ELECTRICALCONSIDERATIONS
8UNITS= 12UNITS=
4X2 LEFT
SIDE
RIGHT
SIDE
5.30 LEFT
SIDE
RIGHT
SIDE

ROOMBOUNDARYLOSSES
EXPRESSEDINdB
(TYPICAL)
AIRLOSSESAT15METERS,
50% RELATIVEHUMIDITY
SCREENLOSSES
(15MILTHICKVINYL,8%OPENING)
FIGURE7,RESPONSEINTHEHOUSE
FIGURE8.ISOSTANDARDPLAYBACKRESPONSE
dB,
RELATIVE
LEVEL
dB,
RELATIVE
LEVEL
dB,
RELATIVE
LEVEL
SUMOFCURVES
A,B,ANDC
dB,
RELATIVE
LEVEL
DATAFROM
FIGURE7

A.4671:Components:
B.4673:Components:
C. 4670A:Components:
D.4672A:Components:
E.4674A:Components:
F.4675:Components:
G. 4676A-1: Components:
H.4676A-2:Components:
1-4507 LowFrequencyEnclosure
1-2225H LowFrequencyTransducer
1-2370 HighFrequencyHorn
1-2425J HighFrequencyDriver
1-311 OANetwork
1-4507 LowFrequencyEnclosure
1-2225H LowFrequencyTransducer
1-2380 HighFrequencyHorn
1-2445J HighFrequencyDriver
1-3115A Network
1-4508 LowFrequencyEnclosure
2-2225JLowFrequencyTransducers
1-2380 HighFrequencyHorn
1-2445J HighFrequencyDriver
1-3152A Network
1-4560BKALowFrequencyEnclosure
1-2225H LowFrequencyTransducer
1-2370 HighFrequencyHorn
1-2425J HighFrequencyDriver
1-311 OANetwork
1-4560BKALowFrequencyEnclosure
1-2225H LowFrequencyTransducer
1-2380 HighFrequencyHorn
1-2445J HighFrequencyDriver
1-3115A Network
1-4508 LowFrequencyEnclosure
2-2225JLowFrequencyTransducers
1-2360 HighFrequencyHorn
1-2445J HighFrequencyTransducer
1-2506 MountingBracket
1-3152A Network
1-4550BKALowFrequencyEnclosure
2-2225JLowFrequencyTransducers
1-2360 HighFrequencyHorn
1-2445J HighFrequencyTransducer
1-2506 MountingBracket
1-3152A Network
2-4550BKALowFrequencyEnclosures
4-2225HLowFrequencyTransducers
2-2365HighFrequencyHorns
2-2445JHighFrequencyDrivers
2-2506MountingBrackets
1-3152A Network
FIGURE9.JBLTHEATERSYSTEMSCOMPONENTSANDWIRINGDIAGRAMS

J. WiringDiagramfor:
4671
4672A
4673
4674
K.WiringDiagramfor:
4670A
4675A
4676A-1
FIGURE9,CONT'D.
• 2225H

L.WiringDiagramfor:
4676A-2
Note: SplayeachHFHorn221/2°offcenter
(TotalSplayangleof45°)
FIGURE9,CONT'D.
FIGURE10.LFENCLOSUREASSEMBLYINSTRUCTIONS
3152A
A.MOUNTINGLFTRANSCLUCERSIN4507,4508,
AND4518 B.MOUNTINGLFTRANSDUCERSIN4550BKA
AND4560BKA

HORN/DRIVER
SCREWEDINPLACE
BI-RADIALHORN
4WOODSCREWS
INTOFRONTEDGE
OFLFENCLOSURE
LFENCLOSURE
FIGURE11.MOUNTINGHORNSINTHEATERSYSTEMS
ANGLEIRON'
PANELREMOVED
2506ADAPTER
HFDRIVER

FIGURE12.MOUNTINGNETWORKS
INCLUDED
WITH
NETWORK
INSERT
T-NUTS
#6
SCREWS
TERMINALBOARD
PLATEREMOVED
FROMINSIDE

JBLIncorporated
RO. Box 2200
8500BalboaBoulevard
Northridge,California91329 U.S.A.