JBL 5231 User manual

ProfessionalSeries
Technical Manual
ElectronicFrequency
Dividing Networks
5231 Single Channel
5232Dual Channel

Index
The JBL5231and 5232
ElectronicFrequencyDividingNetworks 1
Installation 1
Operation 5
Appendix 6
ServiceNotes 8
ProfessionalDivisionWarranty
every JBL ProfessionalSerieselectronicproduct is
guaranteedagainstdefects in material and workmanship fora
period oftwo years. JBL willreplacedefectiveparts and make
necessaryrepairsunderthiswarranty ifour examination
revealsevidence of faultyworkmanship or material. The
warrantydoes not coverdamagecaused by misuse,accident
orneglect. JBL retains the exclusiveright to makesuchdeter-
mination onthe basis of factoryinspection.
If itis impractical to return the productto the factory,please
write JBL describing the difficulty or malfunction. JBL may, at
itsoption,establishalternativerepairprocedures or furnish
replacementparts as appropriate.Productsreturned tothe
factorymust be shippedprepaid.
Thewarranty onJBL productsshallremainvalidonly if
repairs are performed byJBLor under its authorizedpro-
cedures, and providedthat the serialnumber onthe unit has
notbeendefaced
or removed.
JBLcontinuallyengages in researchrelated to productimprovement.
Newmaterials,productionmethods and designrefinements are
introducedintoexistingproductswithoutnotice asa routineexpression
ofthatphilosophy. For thisreason, any current JBL product may differ
insomerespectfrom its publisheddescription butis alwayswarranted
toequal or exceed the originaldesignspecificationsunlessotherwise
stated.

TheJBL5231andS232
ElectronicFrequencyDividingNetworks
The5231and5232aredesignedforusewithstudiomonitor
orsoundreinforcementloudspeakersystemswherebi-
amplificationortri-amplificationisdesirable.The5231(single
channel)and5232(dualchannel)featureunbalanced,
highimpedanceinputs,unitygaininthepassbandand
unbalancedlowimpedanceoutputs.The5231willprovidea
singlechannelcrossover.The5232providestwoseparate
channelswithindependentcrossoveraction(asina stereo
installation).
Thepowerswitchandpilotlightfortheunitanda high
frequencylevelcontrolforeachchannelareonthefrontpanel
foreasyaccess.Thecrossoverfrequencyatwhicheach
channelisoperatingisindicatedthrougha frontpanel
window.EithermodelcanbemountedinoneEIAstandard
rackspace.
Thedesiredcrossoverfrequencyisobtainedbyinserting
thecorrespondingprintedcircuitcardintoeachchannel's
circuitry.Crossovercardsareavailableforthecommonly
usedfrequenciesof500Hzand800Hz.Filterslopesare
12dBperoctavewithhighandlowfrequencyoutputattenu-
ated3 dBatthecrossoverpoint.Cardsarealsoavailablewith
thespecificcrossovercharacteristicsrequiredfortheJBL
4330,4332,4340or4350bi-amplifiedstudiomonitors.In
addition, blankcardscanbeobtainedforconstructionof
crossovernetworksforotherfrequencies(detailsprovidedin
theappendix).
Advantages
1. Lower Distortion—The useofelectronicfrequencydividing
networksandmultipleamplifierspermitsdeliveryofoptimum
poweroverthedesiredaudiospectrumwithminimumdistor-
tion. Bydividingtheaudiospectrumpriortoamplification,the
individuallowfrequencyandhighfrequencyamplifierscan
performtheirfunctionswithgreatereffectiveness.
2. Flexibility—\n soundreinforcementapplicationsitisoften
desirabletocombineonelowfrequencydriverwithseveral
highfrequencyunitstoobtaina controlleddispersionpattern;
thus, onemayselectamplifiersoftheappropriatepowerfor
eachgroupoftransducers.
3.Cost Savings—When severalloudspeakersystemsareto
beconnectedtoa singlechannel,significantcostsavingscan
berealizedsinceonlyoneelectronicfrequencydividingnet-
workneedbeused,therebyeliminatingthehighlevelpassive
crossovernetworksnormallyrequiredforeachofthe loud-
speakersystems.Moreover,sincenopowerisdissipatedin
resistiveattenuators,theamplifierrequirementsforhigh
powersoundsystemsmaybesubstantiallylessthanwhen
highleveldividingnetworksareused.
Installation
Theelectronicfrequencydividingnetworkreceivesthepro-
gramsignalfroma linelevelsource—anaudiopreamplifier,
studiomixdownconsoleorportablemixer—andseparatesthe
signalintohighandlowfrequencybands.Outputsfromthe
networkfeedtheappropriatepoweramplifiers.Eachamplifier,
in turn, drivesitsrespectiveloudspeakersystemcomponents.
TypicalinstallationsarediagrammedinFigure1.
1

ConventionalPassiveNetworks
PROGRAM
SOURCE LOUDSPEAKERSYSTEM
ONE
AMPLIFIER
PASSIVE
FREQUENCY
DIVIDING
NETWORK
Two-Way System
LOUDSPEAKERSYSTEM
PROGRAM
SOURCE
ONE
AMPLIFIER
PASSIVE
FREQUENCY
DIVIDING
NETWORKS
Three-Way System
ElectronicNetworks
PROGRAM
SOURCE LOUDSPEAKERSYSTEM
TWO
AMPLIFIERS
ACTIVE
FREQUENCY
DIVIDING
NETWORK
Two-Way System with Single Channel Active Crossover
PROGRAM
SOURCE
THREE
AMPLIFIERS
LOUDSPEAKERSYSTEM
5232
ACTIVE
FREQUENCY
DIVIDING
NETWORK
Three-Way System with Dual Channel Active Crossover
Figure 1. Typical Installations Of The 5231 And 5232 Compared To
Conventional Passive Networks
Whenevera midrangeorhighfrequencydriverisconnected
directlytoa poweramplifier,a series capacitorisrecom-
mendedtoattenuateunwantedlowfrequency "on-off"
switchingtransientsignalswhichcandamagethedriver.
SpecificcapacitorvaluesaregiveninTable1.
PROGRAM
SOURCE
PROGRAM
SOURCE
ACTIVE
FREQUENCY
DIVIDING
NETWORK
TwoIndependentTwo-WaySystemswithDuaiChannelActiveCrossover
2
1 HIGH
MIO
LOW
S231
HIGH
LOW
HF
LF
CHANNEL
2
CHANNEL
1
HF
LF
HF
,LF
HIGH
MID
LOW
CHANNEL
2
5232
CHANNEL
1
HF
LF
FOUR
AMPLIFIERS LOUDSPEAKERSYSTEM
HF
LF
HIGH
LOW
HIGH
LOW
LOUDSPEAKERSYSTEM

LOUDSPEAKERSYSTEM
PROGRAM
SOURCE
ACTIVE
FREQUENCY
DIVIDING
NETWORK
2. Alignthethreeholes in eachcrossovercardwith the
correspondingmountingpins onthe mainprintedcircuit
board. Thecomponents onthe cardshouldfacetoward the
chassiswiththefrequencydesignationlabeloriented
towardthefrontpanel.
3. As thecard is gentlypressedagainstthemounting pin
stops(approximately1/4"),electricalconnectionwill be
madebetween the cardconnectorand six pins onthe
printedcircuitboard.
4. Replacethebottomcoverandsecure it with the four
screws.Theunit isnow ready for mountingandconnection
ofthevariousinputsandoutputs.
Mote: Operation 01 the5231 or 5232withouta crossover
card willnotdamagetheunit-
It is possible to construct a systemusing an electronic low
frequencytransitionand a conventionalpassivenetworkfor
themidrange or highfrequencycrossover.TheJBL4350
StudioMonitor,diagrammedabove, is such a system. Ifa
pair of 4350'sare tobe used, a single5232canaccommodate
bothsystems.Notethatthepassive,highlevelfrequency
dividingnetworkused in the4350alreadyincorporates the
requiredattenuationcapacitors to protectthemidrange and
highfrequencydrivers.
CrossoverCardInsertion
Priortoinstallingthe5231 or 5232, a crossovercardmust be
inserted in eachchannel as follows:
1. Placethe5231 or 5232upsidedown ona softsurface,
removethetwoPhillips-headscrewsfromeitherside of
thecaseandliftthebottomcoverfromthechassis.
4
Table1. Minimum Values
For LowFrequency
AttenuationCapacitors
The abovecapacitors are availablefrom any electronicsparts
supplier. Capacitorbreakdownvoltagesshould be greaterthan 75V.
Do notuse polarizedelectrolyticcapacitors;paper or Mylar
capacitors are acceptable. If voltageacross the protecteddriver
exceeds the voltage atthe output ofthe amplifier at frequenciesjust
below crossover, a resistormust be placed in parallelwith the
drivers. The resistorshouldhave a minimumvalue of twice the rated
impedance ofthe driver.
The crossover card is pressed on to mounting pins as shown. Note
the use of two hands to maintain proper alignment tor installation or
removal of the card.
Input and output terminals of the 5231 and 5232.
TWO
AMPLIFIERS
HF
LF
5231
LOW
PASSIVE FREQUENCY
DIVIDING NETWORK
ULTRA-HIGH
HIGH
MID
Figure 2. Combining Electronic And Passive Frequency
Dividing Networks
Crossover Frequency
Driver Impedaqe®^^
4 ohms cl£>mf$16 ohms
250 Hzto 500 Hz_^*»
Above 500JHgJf>^r1z
.'20O0 /if 100.0 /xf 50.0 /if
100.0 /if 50.0 /if 25.0 /if
10.0/if 5.0/if2.5/if
Mounting
The5231 or 5232can be mounted ina singleEIAstandard
rackspacewithoutadditionalbracing or ventilation. Air
externalconnections are made onthe rearpanel.Mounting
hardware is suppliedwitheachunit.

Connections
Shieldedcable is required at allinputandoutputsignal con-
nections. If cablelengthsgreaterthan15 to 20feetare
requiredbetweentheelectroniccrossoverandthepower
amplifier, itis recommendedthatisolationtransformers or
isolationlineamplifiersbeconnected to theoutput of the
crossovertoreducethepossibility of inducedRFinterference
orhum.
Input Connections—Inputs to the5231and5232areforan
unbalancedlinelevelsource.Screwterminalsontherear
panelareprovidedforconnection of eachinputandare
clearlyidentified.
Output Connections—Each outputchannelcandeliver6.2
voltsinto2000ohms(+18dBreferenced to 0.775volts). A
separatepair of screwterminals,locatedontherearpanel, is
providedforthelowandhighfrequencyoutput of each
channel. Outputswilldrivethehigh-impedance(bridging)line
input of anyconventionalamplifier.Typically,theimpedance
of a bridginginput isat least5000ohms(usually10,000ohms
ormore),therefore,two or morepoweramplifierscan be
drivenby a singleelectronicfrequencydividingnetwork.
PROGRAM
SOURCE
AMPLIFIER
DualChannelBi-ampiificatlon
5232ELECTRONICFREQUENCYDJVIDINGNETWORK
PROGRAM
SOURCE
PROGRAM
SOURCE
5232
Figure3. The Wiring Diagram
AMPLIFIER
AMPLIFIER
AMPLIFIER
AMPLIFIER
4
SingleChannel Bi-amplification
S231ELECTRONICFREQUENCYDIVIDINGNETWORK AMPLIFIER LOUDSPEAKERSYSTEM
HIGH
LOW
5231
CHANNEL 2
CHANNEL 1
LOUDSPEAKERSYSTEM
CHANNEL 1
LOUDSPEAKERSYSTEM
CHANNEL 2
HIGH
LOW
HIGH
LOW

SingleChannelTri-ampllficatlon
5232ELECTRONICFREQUENCYDIVIDINGNETWORK
PROGRAM
SOURCE
Shieldedcable is necessary forall input and outputconnections, as
shown. Makecertainthat the shield is properlyconnected tothe
groundterminal.
AMPLIFIER
AMPLIFIER
AMPLIFIER
LOUDSPEAKERSYSTEM
Operation
Verification Of SystemWiring
It is imperativethateachoutput ofthe electronicfrequency
dividingnetwork be properlyconnected.Inadvertent
exchange oflowand highfrequencyoutputconnections—
at the network,poweramplifiers or transducers—may
result in severedamage to midrange or highfrequency
loudspeakersystemcomponents.
Thefollowingprocedureshould be followed for each
programchannelprior to operation.
1. With ail poweroff, setthe HighFrequencyLevelcontrol at
"2" and adjust the programsourcelevel to minimum. (The
sourcematerial maybe wide-bandnoise or music.) Ifthe
poweramplifiers are equippedwithlevelcontrols,adjust
them to approximatelyone-quarterpower.
2. Turn onthe programsource,network and amplifiers forthe
channelundertest.
3.Graduallyincrease the programsourcevolumeleveluntil
audible.
If the soundcomespredominatelyfrom the midrange or
highfrequencydrivers,immediatelyshutpower offand
check all wiring.
4.Ifthelow frequencyloudspeakerproducesbass,gradually
advance the HighFrequencyLevelcontrol.
Correctsystemwiringwill be verified ifthe treblecom-
^ponent ofthe programmaterialsimultaneouslyincreases in
levelwhilecomingfrom the midrange and highfrequency
drivers.
TransducerPhasing
Oneimportantfactorcontributing tothe naturalsound
character ofa loudspeakersystem isthe phaserelationship of
thetransducers foran octavebelow and aboveeachcross-
overfrequency. Two suitablemethods for establishingproper
phase ofthe components ina two-wayloudspeakersystem
aredescribed inthe followingparagraphs.Either onemaybe
used, depending onthe availability of testequipment. A three-
orfour-waysystemshould be treated ina similarmanner by
firstestablishing the properphase forthe transducers ofthe
lowfrequencytransition and thenprogressing tothe mid- .
range,highfrequency or ultra-highfrequencytransducers,
asapplicable.
Objective Method—A realtimethirdoctaveanalyzer, con-
densermicrophone anda pinknoisesource canbe used to
establishproperphase ofthe loudspeakersystemcom-
ponents as follows:
1. Usingpinknoise as programmaterial,adjustsystem
volume for comfortablelistening andsetthe levels ofthe
individualtransducers to displayflattestoverallfrequency
response onthe realtimeanalyzer.
2. Reversepolarity ofthe highfrequencydriverandobserve
theeffect on frequencyresponsethrough the crossover
region.
Properphasing ofthe transducerswillhavebeenachieved
when the flattestfrequencyresponse has beenobtained
through the crossoverregion, as shown onthe realtime
analyzer.
5
5232
HIGH
MID
LOW
Figure 3.The Wiring Diagram

Subjective Method—If testinstrumentationisnotavailable,
properresultscanbeobtainedbasedonprogrammaterial
asfollows:
1. Adjustvolumelevelforcomfortablelisteningandset
approximatesystembalanceusingpinknoiseorthenoise
heardbetweenstationsofanFMtuner.
2. Listentoa recordingofa malevoicelongenoughto
becomeaccustomedtotheperformanceofthe loud-
speakersystem.
3.Reversepolarityofthehighfrequencyloudspeaker,which
willproducea changeinvoicecharacter.
Whenthetransducersareproperlyphased,a recorded
malevoiceshouldsoundnaturalandexhibitpresence(oran
"upfront"quality),ascontrastedtoanundesirable"hollow"
soundthatcanbeheardwhentransducersareoutofphase.
Note: Ifthecrossoverfrequencyliesabove2000Hz,
"eversingpolarityofthehighfrequencycomponentwill
„reateverylittle,ifany,perceptibledifferenceinsystem
performance.The"correct"polaritywillbethatwhich
yieldsthemostnaturalqualitywitha varietyofprogram
material.
Onceproperphaseamongthetransducersofa loud-
speakersystemhasbeendetermined,otherloudspeaker
systemsintheinstallation(assumingtheyarethesame)may
bephasedaccordingly.Ifdifferentloudspeakersystemsare
used, establishcommonphaseamongthelowfrequency
driversandfollowtheaboveproceduresforeachsystem.
LevelControlAdjustment
Inmostinstances,manufacturersofmulti-amplified loud-
speakersystemsprovideinstructionsforbalancinglevelsof
theindividualdriversofthesystem.Intheabsenceofformal
instructions,orinthecaseofcustomloudspeakersystems,
balancecanbeestablishedbyadjustinglevelstoachieve
ittestresponseona realtimeanalyzer,asdescribedinthe
transducerphasinginstructionsbeginningonthepreviouspage,
oronthebasisofsubjectiveevaluationoffamiliarprogram
material(or,moreaccurately,byusingpinknoiseorthenoise
betweenFMstations)asdescribedinthefollowingparagraphs.
Eachprogramchannelshouldbeadjustedindividually;
subjectiveevaluationshouldbemadewhileseatedinthe
normallisteninglocation.Ifsubjectiveanalysisistobeused,
andthepoweramplifiersareequippedwithlevelcontrols,
initiallyadjustthecontrolstoone-halfoftheirfullrotationand
thenregulateasnecessary.
Subjective Adjustment Of Bi-Ampiified Systems—The fol-
lowingappliestoa 5231ortoeachchannelofa 5232usedin
dualchannelbi-amplification.
1. WiththeHighFrequencyLevelcontrolat"0,"adjust
programsourcelevelforcomfortablelistening.
2. Rotatethenetworkcontrolclockwiseuntila satisfactory
highfrequencybalancehasbeenobtainedintheprogram
material. Ifnecessary,trimsourceoramplifierlevels.
Subjective Adjustment Of Tri-Amplified Systems—When
bothchannelsofa 5232areusedfora tri-amplified loud-
speakersystem,itisgenerallyinstalledsothattheChannel1
levelcontrolsimultaneouslyregulatesoutputofbothmid-
rangeandhighfrequencydriversandtheChannel2 level
controlgovernsonlythehighfrequencydriver.
1. WithbothHighFrequencyLevelcontrolsat"0,"adjustthe
sourcelevelforcomfortablelistening.
2. RotatetheChannel1 levelcontrolclockwiseuntila satis-
factorymidrangelevelhasbeenobtainedintheprogram
material. Ifnecessary,adjustsourceoramplifierlevels
asappropriate.
3.IncreasetheChannel2 leveluntila satisfactoryhigh
frequencybalancehasbeenobtained.Itmaybenecessary
toreadjustmidrange,sourceoramplifierlevelstoachieve
themostdesirableoverallbalanceoftheloudspeaker
system.
Oncehighfrequencyandamplifieroutputlevelshavebeen
established,readjustmentisnotgenerallyneeded.Some
methodofmarkingorlockingthepoweramplifierlevel
controlsisrecommended.
Appendix
BlankCrossoverCardAssembly
Inadditiontothestandardcrossovercards,circuitsforcross-
overfrequenciesof900Hz,1100Hz,1200Hz,1500Hz,
2000Hz,2500Hz,5000Hz,6000Hz,7000Hzand9500Hz
maybeassembledona blankcrossovercard(JBLModel
52-5120)usingstandardcomponents.Filterslopes
(12dB/octave)areidenticaltothoseofthestandardcross-
overcards.Thecircuitsaredesignedtousefiveidentical
resistorsandfiveidenticalcapacitors.Thecrossover
frequencycanbewrittenonthecardbracketandwillappear
throughthefrontpanelwindowofthenetwork.
6

ComponentvaluesforthevariousfrequenciesarelistedinTable2.
Componentsshouldrestagainsttheprintedcircuitboard.Leads
shouldbesolderedandcutflush.
Table2.
Blank Crossover Card
Component Values
Crossover Capacitors Resistors
Frequency C1-C5 R1-R5
(Hertz) (microfarads) (ohms)
900 .012000 10k
1100 .010000 10k
1200 .008200 11k
1500 .008200 9.1k
2000 .004700 12k
2500 .001800 24k
5000 .001500 15k
6000 .001200 16k
7000 .001500 11k
9500 .001200 10k
Note:Resistorsareall1/4-Watt,5%tolerance.Capacitors
areall5%tolerance,SEACORorAMPEREXmetalized
polyester,orequivalent.
PartsList
Servicingshouldbereferredtoqualifiedpersonnel.
Alistofmajorpartshasbeenincludedforconvenience.
SchematicReference
Number
JBLPart
Number Description
5231 5232
TRANSFORMER
T301 T301 51325 Power
Transformer
DIODES
CR401,402,
403,404
CR405,
406
CR401,
402,403,
404
CR405,
406
39869
52225
IN4003
1N4746
TRANSISTORS
Q401
Q402
Q401
Q402
48342
48341 MPSU06(NPN)1
-MPSU56(PNP)1
INTEGRATED
CIRCUITS
U401,402,
403
U401s402,
403,404,
405,406
-513662 RC4131DN3
OTHER
R407
DS101
S101
R407, 414
DS101
S101
51367
82515
84733
Pot,10,000-ohm,
10% logtaper
PilotLight
PowerSwitch
IMPSreferstoMotoroladevices
2May beJBLP/N53510,MotorolaP/N MC1741SC P1.
3RC referstoRaytheondevices
Figure4.Blank Crossover Card
WRITE
FREQUENCY
HERE

ServiceNotes
The5231and5232utilizeintegratedcircuitry.Properopera-
tioncanbeverifiedbymeasurementofDCoutputvoltagesfor
eachintegratedcircuitwhichshouldmeasure0,±Vi VDC.If
thisspecificationisnotmet,theintegratedcircuitisdefective
andshouldbereplaced.
DCvoltagesaremeasuredwithrespecttoground.Itshould
benotedthata DCvoltmeterhavinga highinputimpedance
(10megohmsorgreater)isrecommended.
8

Power Supply
Schematic Diagram Of The 5232 Electronic Frequency
Dividing Network
Theschematicofthe5231isidentical,withexception
ofthereferencedesignations(R201etc.).The
appropriateschematicispackedwiththeunits
concerned.
FREQ SELECT