JBL Professional Series User manual

ProfessionalSeries
TechnicalManual
Model4311
ControlMonitor

Index
ProfessionalDivisionWarranty1
Specifications1
The4311ControlMonitor2
TestParameters3
Installation4
Maintenance5
AdditionalInformation5
ProfessionalDivisionWarranty
EveryJBLProfessionalSeriestransducerisguaranteed
againstdefectsinmaterialandworkmanshipfora periodof
fiveyears.JBLelectronicproductsarewarrantedfora
periodoftwoyears.JBLwillreplacedefectivepartsand
makenecessaryrepairsunderthiswarrantyifourexam-
inationrevealsevidenceoffaultyworkmanshipormaterial.
Thewarrantydoesnotcoverdamagecausedbymisuse,
accidentorneglect.JBLretainstheexclusiverighttomake
suchdeterminationonthebasisoffactoryinspection.
Moreover,becausewebelievethata fineloudspeaker,
likea finemusicalinstrument,shouldneverwearout,we
willrepairanyJBLtransducerfreeofchargewithouttime
limitationiffactoryinspectiondisclosesevidenceofan
originalmanufacturingdefect.
Ifitisimpracticaltoreturntheproducttothefactory,
pleasewriteJBLdescribingthedifficultyormalfunction.
JBLmay,atitsoption,establishalternativerepairproce-
duresorfurnishreplacementpartsasappropriate.
Productsreturnedtothefactorymustbeshippedprepaid
andwillnotbeacceptedunlesswrittenauthorizationhas
firstbeenobtained.
ThewarrantyonJBLproductsshallremainvalidonly
ifrepairsareperformedbyJBLorunderitsauthorized
procedures,andprovidedthattheserialnumberonthe
unithasnotbeendefacedorremoved.
PowerCapacity' 75Wattscontinuousprogram
CrossoverFrequencies 1500and6000Hz
NominalImpedance 8ohms
HighFrequencyDispersion 90°horizontalandvertical
FrequencyResponse 45-15,000Hz±3dB
Sensitivity2 42dBat30teetwitha 1-mWinput
averaged500to2500Hz,
withcontrolssetforflattest
response
81dBat10feetwitha 1-Watt input,
averaged500to2500Hz,with
controlssetforflattestresponse
LowFrequencyLoudspeaker
NominalDiameter 12inches30cm
VoiceCoil 3-inch(7.6cm)edgewoundcopper
ribbon
MagneticAssemblyWeight 6.75pounds3.1kg
FluxDensity 10,400gauss
Sensitivity3 42dB
MidrangeTransducer
NominalDiameter 5inches13cm
VoiceCoil %-inch(2.2cm)copper
MagneticAssemblyWeight 2.75pounds1.2kg
FluxDensity 16,500gauss
Sensitivity
(averaged1-3kHz) 46dB
HighFrequencyDirectRadiator
NominalDiameter 1.4inches3.6cm
VoiceCoil %-inch(1.6cm)copper
MagneticAssemblyWeight 1.6pounds0.7kg
FluxDensity 15,000gauss
Sensitivity
(averagedabove2 kHz) 47dB
Finish Texturedgrayoroiledwalnutwith
blackfabricgrille
Dimensions 23Vx 14Vx 11Vdeep
60x36x30cmdeep
NetWeight 42lbs19kg
ShippingWeight 49lbs22kg
'SeeInstallationsectionforamplifierpowerrecommendation,
2Note:
Unlikemany"theatretype"loudspeakersystemsthatexhibitariseinthe
midrangeregion,the4311isa truemonitorprovidingsubstantiallythesame
sensitivitythroughthefullrangeofaudiblefrequencies.Measuredsensitivity
below500Hzorabove2000Hzmaybeconsiderablygreaterthanthatof
othersystemswithhigherEIAsensitivityratings.
3Sincethemajorportionoftheenergyreproducedbythelowfrequency
loud-
speakerliesbelow800Hz,thisspecificationhasbeendevelopedbyusinga
testsignalwarbledfrom100to500Hz,ratherthantheconventional1-kHz
sinewavetestsignalonwhichtheEIAsensitivityisbased.
Specifications

The4311ControlMonitor
AproductofJBL'slongexperienceandintimateinvolvement
withtherecordingindustry,the4311isa powerful,yetcom-
pact,monitorloudspeakersystem.Itswide-bandreproduction
atloudnesslevelsrequiredinprofessionalworkmakesthe
4311ideallysuitedforcontrolroominstallations,small
studios,mixdownfacilities,broadcastmonitorsandportable
playbacksystems.
Components
Low Frequency-Bass materialisreproducedbya powerful,
longexcursion,12-inchloudspeakerhavinga 3-inchdiam-
eteredgewoundcopperribbonvoicecoiloperatingina
magneticfieldof10,400gauss.Themagneticassembly,
energizedbyanAlnicoV magnet,weighs6.75pounds:free
airresonanceis22Hz.Thesurfaceoftheconeiscoated
withanexclusivedampingformulationthatprovidesmass
anddensitytooptimizebassperformance,preventspurious
resonanceandprovidesmoothperformanceextendinginto
themidrangeregion.
2

Midrange —Transitiontothemidrangeunitismadeata
crossoverfrequencyof1500Hz.The5-inchtransducer
providesclarityandfreedomfromdistortion,evenatthehigh
loudnesslevelsencounteredinprofessionalapplications.
ThetransducerisenergizedbyanAlnicoV magnethoused
ina closedassemblyhavinga totalweightof2.75pounds
andcreatinga magneticfieldof16,500gauss.The%-inch
diametercoppervoicecoildrivesa 4-inch,edge-damped
conethatoperatesasa truepiston,providingsmooth
frequencyresponseandwidedispersionthroughoutits
operatingrange.
High Frequency- Reproductionabove6000Hzisaccom-
plishedbya 1.4-inch directradiator.Its 1.6-pound magnetic
assemblyand%-inchdiametercoppervoicecoildrivea
coneandcenterdomewithcontrolledlinearityassuredby
animpregnatedclothtermination.Thevoice coil, suspended
ina magneticfieldof15,000gauss,isunusuallylargein
relationtoconesizeforefficiencyandexceptionaltransient
response.Thesmallconediameterisresponsibleforwide,
uniformdispersionofhighfrequencyenergy:a ringofdense
foamsurroundsthemovingassemblytodampunwanted
radiationandreflections.
Dividing Network—The frequencydividingnetworkinstalled
inthe4311hasbeendesignedandtestedtoachievethe
smoothestpossibletransitionsbetweencomponent loud-
speakers.Allnetworkcomponentsareofthehighestquality.
Capacitorsarenon-inductive,non-polarizedtypeswithhigh
ACcurrentcapacitybuiltexpresslyforuseindividingnet-
worksandindividuallytestedforconformitytorigidperform-
ancestandards.
Enclosure —AswithallJBLloudspeakersystems,thecom-
ponenttransducers,frequencydividingnetworkanden-
closurearedesignedandtestedtofunctionasa single,
integratedunit.Theenclosureissolidlyconstructedof%-
inchstockthroughoutwithlock-mitered,wood-weldedjoints
topreventunwantedresonance.Internalpaddingabsorbs
spuriousreflectionsandstandingwaves.Allcomponents
mountdirectlytothebafflepanelandareremovablefrom
thefrontoftheenclosure.A ductedportprovidesproper
acousticalloadingofthelowfrequencyloudspeaker.
TestParameters
Theaccompanyinggraphandspecificationswerecompiled
frommeasurementsmadeunderstandardlaboratorytest
conditions.Theloudspeakersystemwasmountedflushin
thecenterofa large,flatbaffleinananechoicenvironment:
acalibratedcondensermicrophonewassuspendedata
knowndistancefromthesoundsource,sufficientlyfartobe
safelyoutofthenear field; andallelectronicequipmentwas
checkedandcalibratedbeforetestswererun.
Theon-axisfrequencyresponseofa typical4311doesnot
varymorethan±3dBfrom45to15,000Hz.Duetothe
wide-anglecharacteristicsofthemidrangeandhighfre-
quencyunitsandtheirphysicalorientation,response
measuredupto45°off-axis,horizontallyorvertically,does
notdeviatemorethan6 dBfromon-axisresponseat2 kHz
normorethan10dBat8 kHz.The4311slackofdistortion
isequallyoutstanding.Distortionisinaudibleevenathigh
powerlevelsandatverylowfrequencies,asshowninthe
photo.
35-Hz Output
Thisunretouchedphotoshowstheacousticoutputofthesystem
whendrivenbya 50-WattRMSsinewavesignalat35HzA labora-
torymicrophonewasusedtopickupthesoundfromthe 4311. The
signalfromthemicrophonewasconnecteddirectlytoanoscillo-
scopeandthetracephotographed.
Sustainedperformanceatthisintensitywouldnotbeencountered
duringnormaluse.A 50-Wattsinewaverepresentsa farmore
difficultjobfortheloudspeakerthanitsratedcapacityof50Watts
programmaterial,particularlyintheverylowfrequencyrange.Even
so. itcanbeseenthatthe4311producesanalmostperfectsine
wave. (Note:Below50Hz,mostloudspeakersystemsproduce
substantialdistortionwithaninputofonlya fewWatts.)
Responsecontourofsystemwithcontrolsset"flat'.'
(PresenceandBrilliancecontrolseachsetat"5'.')Measuredon-axis
responseofa typical4311,includingallpeaksanddips,doesnot
deviatemorethan3 dBfromtheabovecurve.
3
Bandwidth—On-Axis

installation
Placement
Foroptimumsourcelocalizationwithinthestereoimage,a
pairof4311sshouldbearrangedsothatthelistening posi-
tioniscenteredbetweenthetwosystemsandnomorethan
30degreesoff-axishorizontally.Verticalorientationshould
betreatedina similarmanner.(Note:Smoothestfrequency
responsewillbeheardfroma listeningposition15degrees
off-axisfromeitherunit.)Ifthreeormore4311s areused,the
enclosuresshouldbeangledtowardthehorizontalcenter
lineofthearraytoobtaintherecommendedpatternoverlap
atthelisteningposition.Ifa pairof4311sareplacedhorizon-
tally,andfairlyclosetogether,a widerstereoperspectivewill
berealizedbyorientingtheenclosuressothatthehigh
frequencydirectradiatorsarefurthestapart.Ifphysically
practical, locatingthe4311ssothatthehighfrequencyunits
arenearearlevelisgenerallypreferable.
SystemConnection
Inputtothe4311isviaspring-loadedterminalpostslocated
onthebackoftheenclosure.Theterminalsarecolorcoded
tofacilitateconsistentpolarityconnectionbetweenunitsin
stereoormulti-channelinstallations.Eighteengaugeinsulated
wireistheminimumsizerecommendedforconnectionsup
to50feet.Heaviergaugewireisrecommendedforgreater
distances;16-gaugefrom50to100feetand14-gaugefrom
100to200feet.
Important:Whenconnectingordisconnectingloudspeakersfrom
anamplifier,theamplifiermustbeturnedoff.Makingconnections
whiletheamplifierisoperatingcouldseriouslydamagetheloud-
speakersystemandvoidthewarranty.
SystemAdjustment
Thefrequencydividingnetworkofthe4311isprovidedwith
frontpanelcontrolstoallowseparateregulationofoutputin
the1500to6000Hz"presence"rangeandthe"brilliance"
regionabove6000Hz.Labeled"Presence"and"Brilliance','
thecontrolsarecontinuouslyvariablefrommaximumtofull
off,withtheflattestresponse(measuredinananechoic
environment)achievedatthemidpointsoftheirtravel.With
suitablesettingsofthetwocontrols,thefrequencyresponse
contourofthe4311canbealteredtocompensateforalmost
anyacousticalenvironment,ortoachievethetonalbalance
desired. Controlscalesareclearlymarkedfrom0 to10,with
"5" astheirmidpoints,sothatspecialsettingscanbelogged
andeasilyresetwhenneeded.
PresenceandBrilliancecontrolsarelocatedonthefrontpanel,
belowthegrille.Flattestresponse,measuredina laboratoryenviron-
ment,willbeachievedwithbothcontrolssetat"5:'/
AmplifierPower
The75-Wattcontinuousprogrampowercapacityofthe4311
isindicativeofan"average"programlevelthatcanbetoler-
atedbythecomponentswithoutdamage;however,transients
canexceedthislevelbya considerablemarginwithout
danger.Toachievetheamplifierpowerreservenecessary
foraccuratetransientreproductionathighloudnesslevels,
the4311maybedrivenbyamplifiersratedupto150Watts
RMS(perchannel).Evenlargeramplifierscanbeemployed
ifnormalprecautionsagainstinputdevicedistortionor
amplifierclippingarefollowed.Forportableinstallations,
amplifiershavingaslittleoutputas10WattsRMS(perchan-
nel)willdrivethe4311touseablevolumelevels.
ComponentRemoval
Tooptimizethesounddispersioncharacteristicsofthe loud-
speakersystem,maintaintheacousticalintegrityofthe
enclosureandfacilitateinspectionandservice,allcompo-
nentsmountdirectlytothebafflepanelandareremovable
fromthefrontoftheenclosure.
Gr/V/e-Thegrilleissecuredtotheenclosurebyhook-and-
pilemountingtapeateachcorneroftheassembly.Toremove
thegrille,graspitatthebottomedgeandgentlyliftitfrom
theenclosure.Toreplacethegrille,repositionitontheen-
closureandapplylightpressureatthecorners.
Low Frequency—The lowfrequencyloudspeakerismounted
withfourPhillips-headscrewsthreadedintoT-nutfasteners
whichareanchoredonthebackofthebafflepanel.After
placingtheenclosureonitsbackona clean,paddedsurface,
carefullyunscrewthemountingscrewswithoutapplying
pressurethatmightdislodgetheT-nuts.Whenthescrews
havebeenremoved,gentlylifttheedgeoftheloudspeaker
framefromthebafflepanel,disconnectthewiresatthe
terminalsandremovetheloudspeakerfromtheenclosure.
Midrange and High Frequency—The midrangetransducer
isheldinplacebyfourself-tappingscrewsateachcorner
ofitsframe.Carefullyremovethescrews,lifttheunitfrom
theenclosureanddisconnecttheleadsattheterminals.The
highfrequencydirectradiatorismountedina similarmanner,
withtheexceptionthatitsinputisviatabconnectors.
Dividing Network-The dividingnetworkismountedtothe
rearofthebaffleandheldinplacebymachinescrewsextend-
ingthroughthefrontofthepanel.Togainaccesstothe
network,removethetransducers,pullthewireleadsfrom
themidrangesub-chamber,disconnecttheleadsatthetab
connectorsontheinputterminalsatthebackoftheenclo-
sure, carefullypeelbackthefoilnameplatewhichconceals
thetwomountingscrews,removethescrewsandliftthe
networkoutthroughthelowfrequencyloudspeakeropen-
ing. Note:Malfunctionofthenetworkishighlyunlikely.Since
thenameplateisgenerallydestroyedduringremoval,itis
notrecommendedthatthenetworkberemovedsimplyfor
thepurposeofinspection

Replacement -Reversetheremovalproceduretoreplace
thesystemcomponents.Mountingscrewsshouldbetight-
enedevenlyandjustenoughtoavoidairleaksbetweenthe
componentsandtheenclosure.
Maintenance
Thegrilleclothisa doubleknitpolyesterfabricselectedfor
acoustictransparency,beauty,physicalstrength,colorfast-
nessandsoilresistance.Itcanbecleanedbygentlydusting
itwitha vacuumcleaner.Stainscanberemovedbyusing
aerosolcleaners,suchasTexizeK2i: Goddard'sDry Clean.
orPenChampQuick n Easy, accordingtoeachmanufac-
turer'sinstructions.
Warning:Cleaningfluidsorothersolventsshouldnotbeused.
Althoughtheymayappeartoremovea stain,liquidcleanerswill
dissolvethebasepaintonthegrilleframebeneaththecloth,
resultinginpermanentdiscolorationofthematerial.
Occasionaldustingwitha clean,softclothwillmaintainthe
finishoftheenclosure.Sinceboththetexturedgrayandoiled
walnutsurfacesaremoistureresistant,a dampclothwill
removemoststains.Milddetergentmaybeusedonthegray
finishtoremovesmudgesormorepersistentstains. Con-
ventionalfurniturewaxesorpolishesshouldnotbeused:
theoiledwalnutenclosure,however,maybetreatedwith
waxspecificallyformulatedforsuchsurfaces.
Thewalnutfinishmayappeartoage.ordryout.astheoil
penetratesdeeperanddeeperintotheveneer.Itmay,there-
fore, bedesirabletore-oiltheenclosuresurfacefromtime
totime.Witheachapplication,thebeautyofthefinishwill
becomemoreobvious,anda warm,richpatinawilleventually
beobtained.
Tore-oila JBLoiledwalnutfinish,useanyoneofthe
severalclearoilfinishingpreparationsavailablethrough
furnitureorhardwareoutlets.Applya liberalamountofthe
preparationovertheentirefinishedsurfaceoftheenclosure.
Intentofifteenminuteswipeofftheremainingoilwitha soft,
clean, drycloth.Smallsurfacescratchescanusuallybe
removedbygentlyrubbingthemoutwithveryfinesteel
wool(4/0grade)andapplyingoiltotheentirepanel.Very
deepscratches,dentsorotherseriousdamageshouldbe
repairedonlybya qualifiedfurniturerefinisher.
Caution: Improperstorageofwipingrags couldresultinspon-
taneouscombustion.Theyshouldbethrownawayorspreadout
todryina well-ventilatedareabeforestorageordisposal.
AdditionalInformation
JBLmaintainsa technicalstafftoanswerquestionspertain-
ingtoprofessionalsoundreinforcement.Detailedtechnical
informationonJBLproductsisavailablefromthesame
source.InquiriesmaybeaddressedtotheApplications
Engineer,ProfessionalDivision,JamesB.LansingSound,
Inc.,3249CasitasAvenue,LosAngeles,California90039.
5
LowFrequency
Midrange
HighFrequency
While
Black, Red
Black
Red Green
Black
TerminalPosts
(rearatenclosure)
Red Red
Black Black
DividingNetwork
Whenreconnectingthewireleadsbetweenthenetwork,input
terminalsandhighfrequencydirectradiator,properpolarityis
assuredbytheconnectors.Connectionstotheothercomponents
arecolorcodedasshown.
Interiorviewofthe4311.

JBLcontinuallyengagesinresearchrelatedtoproductimprovement.
Newmaterials,productionmethodsanddesignrefinementsare
introducedintoexistingproductswithoutnoticeasa routineexpression
ofthatphilosophy.Forthisreason,anycurrentJBLproductmaydifferin
somerespectfromitspublisheddescriptionbutisalwayswarrantedto
equalorexceedtheoriginaldesignspecificationsunlessotherwise
stated.

UBL
ProfessionalDivision
JamesB.LansingSound,Inc..3249CasitasAvenue,LosAngeles,California90039.
50657PTB4311/74Printedin U.S.A.