JBL 4350 User manual

Installation
The 4350hasprovisionformirrorimage mounting ofthehigh
frequencycomponentstominimizeormaximizeacoustic
separationbetween systems, as desired. Thesystemisshipped
with alldriversinstalledinthe"left-hand"configuration.Whenthe
twohignfrequencyunitsareinterchanged with theirrespective
cover platesonthe right sideotthebattle panel, the system will
beconsideredtobeintheright-hand'configuration.Threeof
themoslusefulacousticalarrangementsfora pairof4350sare
shownonthenextpageasexamplesolthe several possibilities,
sucn asinvertedsuspensionor multi-unit arrays, thatexist.
Specific mounting instructionsareprovidedunderComponent
Removal, startingonpage4 ofthismanual.
Determinationofthepreferredconfigurationforeach4350
shouldbemadeonlyafter careful audition(and/ormeasurement)
ofthe total soundreproductionchain with each monitor placed
initsfinalroomposition.Ifadditionaltrebleseparationisdesired,
thehignfrequencycomponentsofthe unit intenoedforright-hand
placementcanberemountedto increase theirphysicaldistance
UtilizingA Pair014350s
Rigfi- ancleft-handnomenclature has been adooteoonly as a
convenient reference. Using :wo 4350s in theright-handconfiguration
wojldorovioeihe sarre separation as a pa1'ofunis in theongma.
lell-handconiigjration
from theothersysterConversely,a reouctionoftreble
seoarationcanbe achieved by mounting thehighfrequency
transducers ottheun.tontne left tominimizetheacoustic
distance between systems. Inmany instances - wiereconsistent
driverspacingispre'erred.orifthelistener is fa'enough from
me enclosures sotnatinaividuaisourdsourcescannot DO
perceived --changingtheconfigurationwillnotbe necessary
The highfrequencyacousticlensispackedwilnIhegrilles m a
separate container.Itshouldoepositionedontheenclosure
baffle panel overthe mouth otthehighfrequencyhorn Mounting
tapeontheDa*flepanelandontheappropriate surfaces ofthe
lens holdsthe unit inposition.
Placement
For optimum sourcelocalization within tnestereoimage,a pair
of4350ssho-ldoearrangedsothatthelisteningpos'tionis
centeredbetweentnetwo systems and nomorethan30°off axis
horizontally (O' 15°vert calty; from eithe' unit Ifthreeormore
4350s areusedtneenclosuresshou'dbeangedtowardihe
nonzontatcenterlineoftnearraytoobtaintherecommendeo
patternoverlapattnehstenirgpositionNote:A minimum
distance ol2.5metres(8 feet) shouldbemaintainedbetweentne
4350 andthelistener
Eye bo'tsareprovidedor.tne bottom oftheenclosuretoallow
invertedsuspension The eyebollsareanchoredtoa neavycuty
stee: braceboitectotnebafflepanelandtotre bottom pane*of
theenclosureTo preserve the clean visual linesoltne enclosure,
the base mayberemovedwnentneeyeboltsare utii zed ifthe
base isremoved [n<ne machine screws threadedmtoT-nuts).the
screws shouldbereplacedtomaintainthe air-tight seal oflhe
acoustic chamber
Grilles
The twogrillesectionsofthe4350are secured tothoenclosure
withmojnting tapeandpositionedbyoowe'pinsattheendsof
each assembly. TheJ3Lnameplate.;ocatecontneuppergme
section. is heldinplace with removablespringciipsAnalternate
mounting positionisprovidedattheoppositeendottnegnieso
thatthenamepiatecanbemovedtoavoointerference with the
nighfrequencycomponentswhentheyaretransferredtothe
nght-handconfigurationThelocatingpinsonthebac<ofthe
narrep.atearearrangedsymmetricallysothatt canberotated
180°toreadccreciiywneneverthe4350isinstalledm the
invertedposition
Connections
Inputtothe4350is through spring-ioadodterminalslocated
onthebackoftheenclosureTwocolo'-coded sets of:e'minals
afe providedancabeedtortheloworhighfrequencysections
oMhesysten Oose've consistentpolantybetweentnetwoinputs
so that botn redte'mmais receive a positivesignalor both receive
a negative s-gna'
Important:WhenconnectingordisconnectingloudspeakersIroman
amplifier,theamplifiermustbeturnedoilMakingconnectionswhile
theamplifierIsoperatingcouldseriouslydamageIheloudspeaker
system andvoidthewarranty.
2
MaximumSeparation
MinimumSeparation
ModerateSeparation

One-mm(18 AWG 3 insulatedwiretstheminimum size
recommendedtorloudspeakerconnectionsupto15m (50ft)
Heavier gaugewire ;S recommendedforgreaterdistances
***-mm(16AWG)upto30m [100ft)and 1 6-mm(14AWG)up
_,0m(200 ft).
System Adjustment
Bi-amplificationolthe4350allowsutilizationoltwomoderately
poweredamplifiersratherthana single,largeamplifier. Since
thepowerdensitydemanded from eachamplifierisreducedin
D-amplification,eachpowersourceis less likelytoapproachits
limitsofdistortion,even though considerablevolumelevelsare
achieved Thelowfrequencyloudspeakersoperateto250Hz
andrequireanattenuationrateof12dBperoctavebelowand
abovethe crossover frequencyTransitionmaybeaccomplished
with a JBL 5233(singlechannel)or5234[dualchannel)
Electronic FrequencyDividingNetworkor with oneotseveral
electronic crossovers or filtering oevices commerciallyavailable
The systemcanbebalancedsubjectivelyusingfamiliar
programmaterialor,moreaccurately, with whitenoise,
pinknoiseorbanosofnoise. Balance canbedetermined
electronicallyusingpinknoiseandadjustingthe output voltage
levels ofthetowandhighfrequencyamplifierssothatiheyare
equal TO eachother,measureoattherespective input terminals
ofthe 4350. Theultra-highfrequencylevelcontrolcanbe
adjustedsubjectivelyorbymeasuring output usingpinknoise
as sourcemateria1..Iflow-levelcrossovernetworksareto
beutilizedforthehighfrequencyanaultra-highfrequency
transitions,complex acoustical testingapparatuswillberequired
forprooerbalancingoftheresultant system Therefore,the4350
is not fitted with terminalconnectionsforanyconfiguration
otherthanthestandardlouospeaker system describedinthis
publication.
Componentinstallationinthe4350enclosure.left-nandconfiguration
"wn. Noteverticalorientationoltheultra-highireouencyt^ansOucer
actionstot.
System andneiworkconnections
viewedIromrearolPeenclosure

AmplifierPower
Tne maximumrecommendedpower input totnelowfrequency
loudspeakersis200 W continuoussinewaveatanImpedance
of4 n.and100W contiruoussirewaveat8 n into the high
freouencysectionLargeramplifierscarbeemployed U normal
precautionsagainst input device distortion oramoifierclipping
are followed
ComponentRemoval
To optimizethesounddispersioncharacteristicsofthe
loudspeaker system, maintaintneacoustical integrity oftne
enclosureandfacilitateinspectionandservice ah components
mount directlytotnebafflepane!andareremovable from the
front oltheenclosure
Loudspeakersystemcomponentsolthe4350Studio Monitor.
Itisrecommendedmattheenclosurebeplaceoonitsback
whenremovinganyofthecomponentsRemovalofthe left low
frequencyloudspeakerisrequiredwhentakingoutthe high
frequencyorultra-highfrequency drivers; however,it is advisable
toremove both lowfrequencyloudspeakerstoprovide
max,mum access totne interior oftheenclosureandasa
safeguardtopreventaccidentaldamagewhicncouldoccurto
tne right lowfrequencyloudspeakerifitwere left inplace.When
convertingthe4350tothenght-nandconfiguration,removalof
both loudspeakersis necessary.
Lett-Hano Configuration
Right-Hand Configuration
Low Frequency and Midrange-The lowfrequencyandmidrange
loudspeakersareeacnsecuredtotheenclosureby four cast
clamps heldinplacebymachine screws threaded into T-nuts
Each loudspeaker can betaken outof theenclosure Oy loosening
the mounting screws, removingtheclampsand lifting the unit
from theenclosure.(Ifitisimpracticaltoplacetheenclosureon
itsback,a loudspeakercanberemovedbylooseningthe four
mounting screws, swingingtheupperclampsoutoftne way. anc
then lifting the unitfrom thelowerclamps) Oncea loudsoeaker
has been lifted afewinches from thebafflepanel,the mout leaas
can oedisconnectedattheterminalsonitsframe.
High Frequency-the high frequencycompressiondriver.
model2440,is bolted totheexponentialhornandsupport
bracket;theassemblyistneninstalledintheenclosure.Thehorn
flangefits into a cutout providedonthebaffleoanelfawhite
vinyl ring gasketonthehorninsuresan airtight seal) andthe
input terminalstotne4350.Observecoisisieni polarity tortheiowand
high frequencysectionsottheloudspeakersystem.
installationofthehigh-frequencycomp'essiondriverandnowareas
shown. Note orientation otthe support oracketa-iduseotlockwashers
meach configuration.

oport bracket is secured with a clamptothefront-to-rearbrace
;he 4350enclosure.Removalisaccomplishedby unbolting
jclamp from theenclosurebrace,takingoutthefour screws
'•ng through thebafflepaneltothehornflange, and lifting
^.ver/horn/bracketassembly from theenclosureThehorn
dbracketcanthenbeunbolted from thecompression
ver Caution To avoidthepossibilityofpersonalinjury,besure
oroperiysupportthednver/horn/bracketassemblywhile
novingthe mounting screws holdingthehorntothebaffle
iei. sincetheassemblyweighsapproximatelyl3HKg[30lb)
*oconvertthe4350toright-handconfiguration,toehigh
quercydnve'/horn/bracketassembly wilt havetobe
archanged with itscorrespondingcoverplateonthe right of
bafflepanel.(The2405ultra-highfrequencydriverw:lialso
/e tobeinterchanged with itsrespectivecoverplate,as
scribed inthe following paragraphs)Thecoverplateis
;uredbehindthebaffle panel byfourmachine screws threaded
•> T-nuts. The supportbracketmustbe taken offthednver/horn
;embly.rotatedt80°andreattachedtotherearflangeofthe
musingtheoriginalhardware(lockwasnersareusedunder
heads oltnetwoooltsthatsecurethe©racket}Theentire
;emoiycanthenbeinsta'ieconthebaffiepanelandthe
jport bracketclamp bolted totheinternalbraceonthe right
e ofthe enclosure. Finally,installthecoverplatebehindthe
•ncutoutonthe left sideofthebafflepaneiusingthe screws
theiditinitsoriginallocation.
"-High Frequency-The 2405ultra-highfrequencydriveris
,d through thebafflepanel from insidetheenclosureand
leldinplacebyfourmachine screws. To achieve tnedesired
persionpatternthe unit mustbepositionedsothatthe
ractionslotisorientedvertically.
Vhen movingthe2405totheright-handconfigurationthe
respondingcoverplateonthe right sideofthebaffiepanel
st beremovedandreinstalledbehindtheopeningoriginally
:upiedbytheultra-nighfreauencydriverThecoverplateis
dmplace with tour machine screws threadednto T-nuts The
ne mounting screws aretobeusedtoinstallthecoverplate
the left sideofthebaffiepane!.
iding Network-Remove thetransducersaspreviously
icribed. pull theleadwires from themidrangesub-chamber
] disconnectthe input leadstothedividingnetworkatthetab
inectorsattachedtothe input terminalsonthebackpanel,
detheenclosure.Theultra-highfrequencyieveicontrolis
untedona sub-panelsecuredtotnebackoftheenclosure
fiepanelby two machine screws extending through thepanel
) threadedfasteners To gam access totnecontro . carefully
j|oftthe serialized foil namepiate.removethe mounting
ews andplacetnecontrolassemblyonthe bottom ofthe
:losure. Thenetworkitselfismountedonthe bottom pane;of
encosure andisheldinplacebysixmachine screws and
Afterremovingthe mounting screws, thenetworKano
molassemblycanoe lifted outoftheenclosure through
er ofthelowfreauencyloudspeakeropenings
e: Malfunctionofthe networK ishighlyunlikely. Since the
namepiategenerallyisdestroyedirremoval,tt;snotrecom-
mendedthatthenetworkberemovedsimplyforthepurpose
ofinspection
Replacement- Reverse theremova:proceduretoreplacethe
system components. Mounting screws forall devices shouldbe
tightenedevenlyandiust tight enoughtopreventairleaks
AlthoughJBLloudspeakersareextremelyrugged,theconeandother
movingpartsaresubjecttoaccidentaldamage. Exercise extreme
cautionwhenever using a screwdriverorothertoolsIntheirimmediate
vicinity.Wheneverthehornisremovedfromthe compression driver,
themouthofthedriver should becoveredwith plastic tape.Anintense
magneticfieldexistsinthemoutholthedriver,andItisextremely
Importantthatforeignobjects such asIron chips, othermetallic
contaminants, mountinghardwareortoolsbekeptfromthearea.
Maintenance
The grilleclothisa double-knitpolyesterfabricselectedfor
acoustic transparency, beauty,physica'strength,color fastness
andsod resisiance Itcanbecleanedbygentlydustingit with a
vacuum cleanerStainscanberemovedbyusingaerosol
cieaners. suchas Texize K2r Goddard'sDry Clean, or Pen
Champ Quick 'n Easy accordingtoeacnmanufacturers
instructions.
Warning:Cleaningfluidsorother solvents should notbe used. Although
theymayappeartoremovea stain,liquidcleanerswilldissolvethe
base paintonthegrilleframebeneaththe cloth, resultinginpermanent
discoloration ofthematerial.
Occasional dusting with a clean, softclothwillmaintanthe
finishoftheenclosure Since both thetexturedgrayandoiled
wainut surfaces aremoisture resistant, adamp c<oth willremove
moststains Mild detergentmaybeusedonthegrayfinishto
removesmudgesormorepersistent stains. Conventional
furniture waxes orpolishesshouldnotbe used; tneoiledwalnut
enclosure, however,maybetreated with waxspecifically
formulatedforsuchsurfaces
The walnutfinishmayappearto age. ordryoutastheoil
penetratesdeeperanddeeper into theveneeritmay,therefore
bedesirabletore-oiltheenclosuresurface from timetotime.
Witheachapplication,theoeautyofthefinishwillbecomemore
obvious,anda warm,richpatinawiileventualy beobtained
To re-oila JBL oiledwalnutfinisnuseanyoneofme severa
clear oilfinishingpreparationsavailable through furnitureor
hardwareoutlets.Applya liberalamountoftheoreparationover
theentirefinishedsurfaceoftheenclosure.Intentofifteen
minuteswipeofftheremainingoil with a soft, clean, drycloth
Sma/ surface scratches can usuallyberemovedbygently
rubbingthem witn veryfinesieelwool(4/0grade)ancapplying
oiltotheentirepanel Very deep scratches, dentsorotherserious
damageshouldoerepairedonlyoy a Qualifiedfurniturerefmtsner
Caution: ImproperstorageofwipingragscouldresultInspontaneous
combustion. Theyshouldbethrownawayorspreadouttodryina
well-ventilatedareabeforestorageor disposal.

Electronic FrequencyDividingNetworks
JBL electronictreauency dnooing networksare availableintwo
configurations. Model 5233forsinglechanneloperationand
Model 5234tordua.channelapplicationsPerformanceand
operationa1characteristicsofthetwomodesareidentical
Bothmodelsaremaximally flat second-orderelectronic
crossover networksdelivenng prec.se control ofthetransitionoy
utilizing activefittersTheyexhibitextremely>ownoiseand
operateat output levelscapableofdrivingthepoweramp'ifier
without distortion Each channelisequipped with a level control
toregulate high frequency output Thecrossoverfrequencyis
determinedbya moduleinsertedm eachcnannel'scircuitryIn
addition tothe250-Hzcrossover cara requiredforuseinthe
4350, insertsare avaifatVefortransi!ionsof500Hz,300Hz.
1.2kH^5 kHzand7 kHzA blankcardisalsoavailablefor
conslruct.onofcircuitrytoprovideothercrossoverpoints.
(hp n?h!f^eC,,n9
theleads,0tow ^equency
louaspeakers
0rbetween
Additional Information
JBL maintainsa techmca1 staffto answer questionspertain.ngto
professionalsound reproductionDetailedtecnnicai information
on JBL productsisavai'ab'e from thesamesource,inquires
maybeaddressedtotheApplicationsEngineer,Professional
Div*ion. James 8 Lansing Sound. Inc8500 Balboa Rouie/ard.
^orthndge.California91329.USA
Caution
h^S^'VV^5,
D
H
roQjcedIt*^350may
cause permanent
heamgi0Ss.athalfratedpower1:5d6 can oegeneratedat six feet)
rnesuggested.maximumexposureis 115 oBAforncmorethan15
ttirotas (US Oeaanmert ofLaborBuflitt)#334)