JBL 5234A Manual

JBL
5234A
INSTALLATION
AND SERVICE
MANUAL

TABLE OF CONTENTS
ARCHITECTURAL SPECIFICATIONS
ARCHITECTURAL SPECIFICATIONS 2
PRODUCT SPECIFICATIONS 3
Electrical 3
Physical 3
INSTALLATION 4
InstallationofStandardCrossoverFrequencyModules4
ProgrammingtheinternalHigh-PassFilters5
Mounting 6
Input Connections6
Output Connections6
Use FloatingorBalancedCablesforLongerRuns6
AC PowerConnectionandLineVoltageConversion7
ProtectionofCompressionDrivers8
SETUP AND OPERATION 9
General Applications9
TypicalSystemsEmployingthe5234A9
A SafetyProcedureforI nitial PoweringUpofTheSystem14
Level Control Adjustment 14
System PhasingandSignalPolarity14
SelectingtheLowFrequencyHigh-PassFilterOptions16
BlankCrossoverCardAssembly16
PARTS LIST 18
SCHEMATIC DIAGRAM19
LIST OF ILLUSTRATIONS
FigureDescription
1 TotalHarmonic Distortion 3
2 5234ALowFrequency Cutoff Characteristics3
3 ScrewRemovaltoLiftOffthe Bottom Cover4
4 Identification of Major ComponentsInside5234A4
5 CrossoverCard Mounting Alignment 4
6 OneoftheTwoProgrammingDIPSwitches5
7DIPSwitchProgrammingandResultantLow5
Frequency Cutoff Characteristics
8 Model 5234A Rear Panel6
9 UsingIsolationTransformerstoFloattheCable6
Betweena 5234A Output andanUnbalanced
Load
10UsinganIsolationTransformertoFloat(or7
Balance) theCableBetweena 5234A Output
anda Floating(orBalanced)Load
11UsinganIsolationTransformertoFloatthe7
I nput Cabletothe5234A
12ConventionalTwo-WaySystem (Passive Network)9
13 ConventionalThree-WaySystem (Passive Network)9
14DualChannelTwo-WaySystem(Biamplified)9
15 SingleChannelThree-WaySystem(Triamplified)10
16DualChannelTwo-WaySystem with Monaural10
Subwoofer(s)
17CombiningElectronicand Passive Frequency10
Dividing Networks
18 Wiring DiagramforBiamplifiedSystem11
19 Wiring DiagramforTriamplifiedSystem12
20 Wiring DiagramforTwo-WaySystem with 13
MonauralSubwoofer(s)
2112dB/OctaveBlankCrossoverCard(JBL16
Model 52-5120) with ComponentDesignations
2218dB/OctaveBlankCrossoverCard(JBL16
Model 51-5130) with ComponentDesignations
Table
1 MaximumValuesforLowFrequency8
Attenuating ProtectionCapacitors
2 JBLProtectionCapacitorsforCompressionDrivers8
3 12dB/OctaveCrossoverCardComponentValues17
418dB/OctaveCrossoverCardComponentValues17
WARNING:Toprevent fire orshockhazard,donotexpose
this unit torainormoisture.
The electronicfrequency dividing network shall
containtwochannels,each with low-levelactive
filters that separatethe program into lowand high
frequencybandsatdesignatedcrossoverfrequency
points. Each channelshallhavea transformerless,
differential amplifier input andseparate buffer
amplifiersforitslowand high frequency outputs.
Input and output connectionsshallbemadevia
either 1 /4inch(6.3mm) phone jacksorscrew
terminals provided ontheunit'srearpanel.
Crossover frequencyselectionshallbeaccom-
plishedby internally mounted plug-in circuit
modules,oneperchannel. Each module shallbe
designated with thecrossoverfrequency, printed
insucha position astobeeasilyread through a
window intheunit's front panel.Thedesignated
crossoverfrequencyshallbethe point atwhich
theslopesofthepassbandcurvescross,andwhere
each is3 dB down from theaveragepassband
output level;this point shallbe within ± 10%of
thedesignatedfrequency.A varietyofmodules
shallbeavailable,not only with different crossover
frequencypoints,butalso with 12dBor18dB
peroctave filter slopes.Blank plug-in modulesshall
beavailable, allowing forthe installation ofsuitable
capacitorsandresistorstoachievecustomcrossover
frequencypoints.
In addition, internally switchselectablelow
frequencyequalizationandsubsonic filtering shall
be provided foreachchannel,enablinglowfre-
quencyresponsetobe optimized while blocking
subsonicenergy below thelowestusablespeaker
frequency.Thesedualinlineswitchesshallallow
the following programmable options, all with
12dBperoctavesloperates(exceptthe flat
responsesetting):
a. Flatfrequencyresponse(e.g.,noL.F.cut-
offfilter).
b.20Hz high pass filter, Q = 0.707(Butter-
worth).
c. 20Hz high pass filter, Q = 2 (6dB boost
at20Hz).
d.30Hz high pass filter, Q = 0.54.
e. 30Hz high pass filter, Q = 0.84.
f.30Hz high pass filter, Q = 2 (6dB boost
at30Hz).
g.40Hz high pass filter, Q = 0.707(Butter-
worth).
h.40Hz high pass filter, Q = 2 (6dB boost
at40Hz).
The internalswitchingshallalsoallow both
channels' lowfrequency outputs tobe combined
into a monauralsignalwhich, with an appropriate
crossoverfrequency,issuitablefor driving a sub-
woofer channelwhilethe high frequency outputs
drivea full-range stereospeakersystem.
The unit shallfitina 44mm(1-3/4inch) high
space ina standard483mm(19inch) equipment
rack. Recessed front-panel adjustmentsshallbe
provided forthe high frequency output levelof
each channel.A recessedrearpanelslideswitch
shallallow operation with nominal 100to120V
2

AC or200to240V ACpowermains.
The unmodified frequencyresponseofthe
dividing networkshallbe20Hzto20kHz,
±0.5dB. Distortion shallbe less than0.01%THD
at+18dBv* into 100kohmsorgreater,or0.03%
THD at+18dBv into a 600ohmload.Signal-to-
noise ratio shallbegreaterthan90dB,measured
overa 20Hzto20kHzequivalentbandwidth.
Isolationbetweenchannelsshallbegreaterthan
70dB.
The electronicfrequency dividing networkshall
bea JBL Model 5234A.
PRODUCT SPECIFICATIONS
ELECTRICAL
Gain
0dBinthepassband
Rated Output Level
6.2V rms(+18dBv*)measured with 20Hzto20kHz
equivalent bandwidth filter
Distortion
0.01% THD,20Hzto20kHz @ +18dBv into a load
greaterthan10kn
Frequency Response
±0.5dB,20Hzto20kHz(high-passfunctions
disengaged)
Input Impedance
Greater than50kn,transformerless differential
amplifiersforbalancedorunbalancedlinelevelsources
Output SourceImpedance
50ohms,unbalanced
Output LoadImpedance
600ohmsorgreater
Channel Isolation
Greater than70dB,20Hzto20kHz
Signal/NoiseRatio
Greater than90dB,20kHzequivalent bandwidth
Controls
CH1 & CH2 High FrequencyLevel(front)
Power On/Off(front)
CH1 & CH2SubsonicFilterCharacteristic(internal)
Line VoltageSelector(rear)
Crossover Frequency& FilterSlope
Selectable by plug-in modules,12dBor18dB/octave,
atfactorydeterminedfrequencies(±10%),special
modulesforcertainJBL monitor speakers,orat
customerdeterminedfrequencies(viablank plug-in
modules)
NOTE: One module isrequiredforeachchannel,the
unit comes from thefactory with "jumper"modules
that passthesignal unfiltered sothe unit functionsa
1:2lineamplifier.
12dB/octave 18dB/octave
Model 52-
Freq.
Model 51- Freq.
5120 Blank
5130Blank
5121 250Hz 5132500Hz
5122 500Hz
5133 800Hz
5123 800Hz
5145 (Specialfor
5124 1200Hz
JBL 4345& 4355)
5125 5000Hz
5127 7000Hz
5130(SpecialforJBL4430& 4435)
5140(SpecialforJB L 4343& 4350)
*The 0 dBvreferenceis0.775V rms.Acrossa 600ohmload,this
voltagerepresentsa powerlevelof1 mW(0dBm).
High Pass Filter(SubsonicCutoff)
12dBperoctave rolloff, the cutoff frequencyand
Qswitchselectable
NOTE: Thesecharacteristicsareswitchselectablevia
theinternalDIPswitches,oneperchannel.
Filter
Level atFilter
Frequency Frequency FilterQ
20Hz
-3dB
0.707
20Hz +6dB 2.0
30Hz
-5.5 dB 0.54
30Hz
-1.5dB
0.84
30Hz +6dB 2.0
40Hz
-3dB
0.707
40Hz +6dB 2.0
Power Requirements
6 watts,100-120or200- 240V AC,50or60Hz
OperatingTemperature
5°C (41°F)to55°C (132°F)
PHYSICAL
Mounting Dimensions
44mmx 483mmx 194mmdeep
(1-3/4inx 19inx 7-5/8indeep)
NetWeight
1.8kg(4lb)
ShippingWeight
3.0kg(6-1/2lb)
Figure1 — TotalHarmonicDistortion
(Distortion componentsindBbelow+18dBv output)
Figure2 — 5234ALowFrequencyCutoffCharacteristics
(Selectable eachchannelbymeansofinternalswitches)
JBL continually engages in research related to product
improvement. New material, production methods and
design refinements are introduced into existing products
without notice as a routine expression of that philosophy.
For this reason, any current JBL product may differ in
some respect from its published description, but will
always equal or exceed the original design specifications
unless otherwise stated.
3

INSTALLATION
WARNING:Inmany cases, installationofthe JBL 5234A
Electronic FrequencyDividingNetworkinvolvesopening
thecovertogain access tointeralcircuitmodulesand
programming switches. Inaddition,conversionoftheline
voltagemayinvolveinstallationofa newpower cord. Since
dangerous ACvoltagesexistinsidetheunit,cautionmust
be exercised. These instructionsareintendedforuseby
qualified service personnelonly.
InstallationofStandard
Crossover FrequencyModules
The dividingnetworkisshippedwitha pairof
52-5120 crossovermodules (cards), eachwithtwo
100 ohmresistorsthatconverteachchannel into
a one-input, two-output unitygaindistribution
amplifier.Thetwocardsthereforeequipthe
5234A tofunctionasa pairofindependentone-
input, two-output amplifiers;thenetworkinputs
can beparalleledtoprovidefouroutputsfroma
single source.The HIGH outputswillbeatunity
gainwhenthe HIGH FREQUENCY LEVEL con-
trolsaresetatmaximum(thecontrolscanbe
turneddownif loss isdesired).
Prior toitsuseasa frequencydividingnetwork,
these jumpered"blank"cardsmustberemoved
fromthe5234Aandtheappropriatefrequency
selection cardsmustbeinstalledintheirplace.
To installthe cards:
1. Place the5234Aupsidedownona soft
surface, removethetwoPhillips-head screws from
eithersideofthe case, and lift the bottom cover
fromthe chassis (Figure3).
2. Removetheoldcrossovercardsby lifting
both sides ofa cardsimultaneouslyandgently
(Figure 4).Frictionfromthethreemountingpins
and theelectricalconnectormustbeovercome.
3. Alignthethreeholesineachnewcrossover
card withthecorrespondingmountingpinsonthe
mainprintedcircuitboard(Figure5).Thecom-
ponentsonthecardshouldfacetowardthe chassis,
withthefrequencydesignationlabeltowardthe
front panel.
4. Aseachcardisgentlypressedagainstthe
mountingpinstops(roughly6 mm,1/4in),
electrical connectionwillbemadebetweenthe
card connectorandsixpinsontheprintedcircuit
board.
5. Unless LFprogrammingistobereset(referto
next topicinthismanual),replacethe bottom
cover, observingtheproperorientation.Thecover
willnot seat properlyinthe chassis ifrotated180°
Secure thecoverwiththefour screws. Theunitis
nowreadyformountingandconnectionofthe
various inputsandoutputs.
NOTE: Operation of the 5234A without a crossover card
will not damage the unit, although neither will it pass any
audio signals.
Figure 3 — Remove These Screws toLiftOfftheBottomCover
Figure 5 — CarefullyAlign Crossover CardwithThreeMounting Pins
&Male Chassis Connector
NOTE: Information regarding the capacitor and resistor
values necessary to "make up" 12 dB/octave and 18 dB/
octave cards, as well as the components used on standard
JBL cards, is given near the end of this manual.
4
CH1 CrossoverCard
CH2 CrossoverCard
Power Supply
Figure 4 — IdentificationofMajorComponentsInside5234A
CH2 ProgrammingSwitches
CH1 ProgrammingSwitches

ProgrammingtheInternalHigh-PassFilters
Insidethe5234A,eachchannelisequipped with
a miniaturebankoffiveOn-Offslideswitches. Each
bankofslidersishousedinsmallrectangularpack-
ageresemblingan integrated circuit,andsincethe
multi-switchhousinghastworowsofpinswhich
secure ittothecircuitboard,itisknownasa dual
in-linepinswitch(hence "DIP"). Each ofthetwo
DIP switchesperformstheidenticalfunctions,one
forChannel1 andthe other forChannel2
(Figure4).
OfthefiveslidersoneachDIPswitch,#1
through #4determinethehigh-pass filter character-
istics ofthechannel,while#5isreservedforcreat-
inga monaurallowfrequency output forthetwo
channels (Figure6).
The 5234Aisshipped with theswitchessetfor
flat lowfrequencyresponseanddiscretelow
frequency outputs. IntheSetupandOperation
sectionofthismanual,considerationsinselecting
thevariouslowfrequency cutoff characteristics
are discussed.Ifa characteristic other thanthe
factorypresetisdesired,itcanbeestablished
as follows:
1. Placethe5234Aupside down ona soft
surface, removethetwoPhillips-headscrews from
eithersideofthe case, and lift the bottom cover
from the chassis (Figure3).
CAUTION: The5234AACpowercordshouldnotbe
connectedtothepowerreceptacle.Also,anypower
amplifierstowhichtheFrequencyDividing Network
maybeconnectedshouldbeturnedOffduringthis
procedure.
2. LocatetheDIP.switch(es)forthechannel(s)
tobeprogrammed.
NOTE: In a triamplified system, use high-pass filtering
only on the channel used for the low-mid/high transition;
the mid/high channel should be set for flat response. In a
biamplified system with a mono subwoofer, both chan-
nels' DIP switch "mono"sliders must be engaged.
3. SettheDIPswitch(es)accordingtothe
information inFigure7.
4. Replace,the bottom cover,observingthe
properorientation.Thecover will notseat
properly inthe chassis if rotated 180°.Secure
thecover with the four screws.The unit isnow
readyfor mounting andconnectionofthe
variousinputsand outputs.
Black square indicates
switch position.
20Hz,Q=0.707
(-3dB@20Hz)
1100
20Hz,Q = 2
(+6dB@20Hz)
1001
30Hz,Q = 0.54
(-5.5dB@30Hz)
0101
30Hz,Q = 0.84
(-1.5dB@30Hz)
00101
FLAT, MONO
1000or0100
30Hz,Q = 2
(+6dB @ 30Hz)
0001
40Hz,Q=0.707
(-3dB@40Hz)
0000
40Hz,Q = 2
(+6dB@40Hz)
MONO(Bothchannels
mustbesetto Mono.)
00100
FLAT (Discretechan-
nels, theFactoryPreset)
Figure7 — DIPSwitchProgrammingfortheVariousHigh-Pass
FilterCharacteristics,& Mono Mode
NOTES:
1. Curvesarelabeledbya binarycode.A "1" = ON(switch
closed), anda "0"= OFF(switchopen).
2. Bitpositions#1and#2selectthe cutoff frequency.
3. Bit position #3,whenclosed,gives flat response.
4. Bit position #4,whenclosed,lowerstheQ.
5. Bit position #5,whenclosedon both channels,combines
theLF outputs toa mono summedsignal.
6. Shadedareasarenotrelevantto function beingdescribed.
5
1101
Figure6 — OneoftheTwoDIPSwitches that AllowProgramming
ofthe Model 5234ALowFrequencyCharacteristics

Figure 8 - Model 5234ARearPanel
Mounting
The 5234Aissuitablefor mounting inoneEIA
standardrackspace without additionalbracingor
ventilation.A full setof mounting hardwareis
included.Alternatively,the unit maybeplacedon
a shelforcountertop.As with anylowlevelsignal
processing electronics,itisadvisablenottomount
the unit neara strongsourceofstrayelectro-
magneticfields,suchasimmediatelynexttothe
powertransformerora largeamplifier.Inany
installation,bearinmindthatallexternalconnec-
tionsaremadeontherearpanel,andthemaximum
allowableambienttemperatureforthe unit is55°C
(132°F).
InputConnections
Inputconnectionstothe5234Amaybeeither
unbalancedorsymmetrical(i.e.floatingorbalanced)
Clearly labeledscrewterminalsandparallel-wired
phone jacks ontherearpanelacceptthelinelevel
input toeachchannel(Figure8).Thephone jacks
are 6.3mm(1/4in)diameter3-circuittype,wired
so thetipisforaudiohigh,theringisforaudiolow,
andthesleeveisforshieldground.Witha balanced
or floating source,usea 3-circuit("stereo"type)
phoneplug.Withanunbalancedsource,thering
andsleeveofthe3-circuitplugmustbeshorted;
thisisautomaticallyaccomplishedbyinsteadusing
a standard2-circuitphoneplug.
NOTES:
1. Exchange of the HIGH (+) and LOW (-) connections
will result in a reversal of signal polarity.
2. Figures 9, 10 & 11 illustrate balanced or floating
input and output connections. Figures 18 through 20
illustrate wiring for typical installations.
OutputConnections
The 5234Aoutputsareunbalanced,deliveringup
to6.2V rms into a 600ohmorhigherimpedance
load(+18dBv). Each channelhasa HIGHfrequency
andLOWfrequency output, andeachofthese out-
putsisavailableattwopointsontherearpanels:
a setofscrewterminalsora parallel-wiredphone
jack (Figure8).Thephone jacks are6.3mm
(1/4 in)diameter2-circuittype,wiredsothetip
is fortheaudiosignalandthesleeveisforthe
common(shieldground).
Use FloatingorBalancedCablesforLonger Runs
Shielded cablesarerequiredforall input and
output signals.Ifthe output cablelengthsare
greaterthan4.5m to6 m (15 to20ft),werecom-
mendinstallingisolationtransformers(600£2:
60012) ateachendofthecable. This allowsdual-
conductorshieldedcabletobeusedina floating
mode,greatlyreducingthepossibilityofradio
frequencyinterference(RFI)orhum.Ifthe
amplifiertowhichthe5234A output isconnected
has a balancedor floating input, onlyonetrans-
formerneedbeinstalled— attheendofthecable
connectedtothe5234A output.
Similarly, longer input cablesshouldbe
balanced or floating toreducesusceptibilityto
RFI andhum.Ifthe output ofthedevicefeeding
the5234Aisbalancedorfloating,notransformer
is requiredatall;simplyusea dual-conductor
shieldedcable.Ifthe input sourceisunbalanced,
an isolationtransformershouldbeusedatthe
source device's output.
Withshortercables,particularlywhereintercon-
nectedequipmentismountedina singlerackor
is poweredbythesameACreceptacle,thereis
less needforbalancedor floating input and output
cables.
Figure 9 — UsingIsolationTransformerstoFloattheCable
Betweena 5234AOutput& AnUnbalancedLoad
TIP-SLEEVE
PHONE PLUG
'TOISOLATION
. TRANSFORMERS, ETC.
UNBALANCED
AMPLIFIER
INPUT
6
AS BELOW
AS BELOW
AS BELOW
INTERCONNECTING
CABLE
ISOLATION
TRANSFORMER
(MOUNT CLOSE
TO 5234A)
CASE AND/OR
ELECTROSTATIC
SHIELD GROUND
ISOLATION
TRANSFORMER
(MOUNT CLOSE
TO AMPLIFIER)
CASE AND/OR
ELECTROSTATIC
SHIELD GROUND,
PLUS CABLE SHIELDS
600 SI: 600 SI
OR

TIP-SLEEVE
PHONEPLUG
INTERCONNECTING
CABLE
TOISOLATION
TRANSFORMER &
INTERCONNECTING CABLE
Figure10— UsingAnIsolationTransformertoFloat(orBalance)theCableBetweena 5234A Output
&a Floating(orBalanced)Load
UNBALANCED
OUTPUTOF
MIXER,GRAPHICEQ,
OR OTHERSIGNAL
SOURCE
ISOLATIONTRANSFORMER
(MOUNT CLOSE TOSIGNAL
SOURCE OUTPUT)
FROMINTERCONNECTING
CABLE & ISOLATION
TRANSFORMER
TIP-RING-SLEEVE
PHONEPLUG
Figure11— UsingAnIsolationTransformertoFloatthe Input Cabletothe 5234A
AC PowerConnection& LineVoltageConversion
The 5234Acanbepowered from either100to
120V ACor200to240V AC50or60Hzmains.
The SUPPLY VOLTAGE SELECT switchonthe
rearpanelconvertsthe unitfrom one operating
rangetothe other (Figure8).Asshipped,the unit
is setfor100to120V ACoperation,andtheline
cord provided issuitableforuseintheU.S.,
Canada or Japan. Toconvertthe unit for operation
with other mainsvoltagesor outlet types,usethe
following procedure.
1. Besurethe5234Aisnotconnectedtoany
powersource.
2. Slidethe SUPPLY VOLTAGE SELECT
switchtothe appropriate range.
3. Executeoneofthesetwoalternatives:
a) Removethe bottom coverby removing the
twosmallPhillipsheadscrewsoneachsideof
the case, (Figure3)andchangetheline cord
toonewhoseattachment plug matchesthe
powerreceptacle.Securethenew cord tothe
chassis with a feed through cableclamp.Also,
besuretosolderthehigh,neutraland ground
conductorstothesameterminals from which
thecorrespondingconductorsofthe original
cord wereremoved.*
—or—
b)Installa suitableadaptertomatethe plug
ontheexistingline cord with thepower
receptacle.
NOTE: Any line cord or adapter used for 200-240 V
operation in the U.S., Canada or Japan must be both
U.L. listed and C.S.A. certified. For 240 VAC,
50/60 Hz operation in other countries, select a line
cord based on governing local regulations.
CAUTION:This unit maybedamagedifoperated
with thesupplyvoltageselectswitchsetincorrectly
forthelinevoltageapplied.Also,verifythemains
areAC since, insomecountriesaswellascertain
areas within theU.S.,DCmainsexist.
*ln U.S.A.versions,theblackwireis "hot", the white wireis
"neutral,"andthegreenwireis ground. InEuropeanversions,
blue is "hot", brown is"neutral,"andgreen/yellowis ground.
7
AS BELOW
AS BELOW
AS BELOW
OR
BALANCED ORFLOATING
AMPLIFIER INPUT
600SI: 600n
ISOLATION
TRANSFORMER
(MOUNT CLOSE
TO 5234A)
JCASE AND/OR
ELECTROSTATIC
SHIELD GROUND
AS BELOW
INTERCONNECTING
CABLE
600SI: 600 SI
OR
10Kn:10KSI

Protection of Compression Drivers
Whenever a midrangeorhighfrequencycom-
pression driverisconnecteddirectlytoa power
amplifier,itisrecommendedthata capacitorbe
wiredin series with thedriverinordertoattenu-
atedunwantedlowfrequencyandswitching
transient signals, andtoblockDCcomponents,
any ofwhichcandamagethedriver. This applies
tomostbiamplifiedandtriamplified systems
employingcompressiondrivers.(Inconventional
systems with passive, high-leveldividingnetworks,
thenetworkcomesbetweenthepoweramplifier
and thedriver(s)sotheprotectionisalready
built-in.)
NOTES:
1. In all JBL monitors which are designed for biamplifi-
cation, the dividing networks already incorporate the
required attenuation capacitors between the inputfs) and
the compression driver(s).
2. Series capacitors are not required for low frequency
and midrange cone or dome type transducers.
CAUTION: Itis imperativethat each output ofthe 5234A
electronic frequencydividingnetwork be properly con-
nected. Inadvertentexchange oflow andhighfrequency
outputconnections (atthe 5234A, the poweramplifiers,
or the transducers) may result in severe damage to midrange
or highfrequencyloudspeaker system components. Ifin
doubt,alwaystest thelow frequencyloudspeaker(s)first,
since the presence of highfrequenciestherewill be less
apt to cause damagethan the converse.
The lowfrequency series protectioncapacitors
shouldbenon-polarizedelectrolytics,eithermylar,
metallizedpolyesterorpolyestertype with working
voltages ofatleast50V.DONOTUSE POLAR-
IZEDELECTROLYTICCAPACITORS. Maximum
capacitance dependsnotonlyonthecrossover
frequencyusedforthedriver,butalsoonthe
driver's impedance,aslistedinTable1.Suitable
10% tolerancecapacitorsareavailabledirectly from
a JBLprofessionalproductsdealerorJBLdirectly;
therecommended values forspecific cutoff fre-
quencies, andtheirJBLpartnumbers,arelisted
intheTable2.
Crossover Frequency
CapacitorValues
(Driver Impedance)
Crossover Frequency
sn
4a
250 Hzto500Hz
40M F
80M F
150MF
500 Hzto 5000 Hz
20M F
40M F
80M F
Above 5000 Hz
2M F
5u F
8uF
Table 1:Maximum Values forLow Frequency Attenuating
Protection Capacitors
Capacitor
Value
JBL
Part Number
For Optimum Results at
These CrossoverFrequencies
(Based on Driver Impedance)
Capacitor
Value
JBL
Part Number
8n
4a
72 MF 52938 275 Hz
550 H/ 1100 Hz
52 MF 52939 400 Hz 750 Hz
1500
Hz
20 MF
53881 1000
Hz
2000 Hz
4000 Hz
16.5MF
1 0358 1200
Hz
2500 Hz
5000 Hz
13.5MF
1035Q' 1500
Hz 3000 Hz
6000 Hz
12 MF
10434 1700
Hz
3500 Hz
7000 Hz
8 MF 10391 2500 Hz
5000 Hz
10000 Hz
7 MF
57529 3000
Hz 6000 Hz
11000 Hz
6 MF 10296 3500 Hz 7000 Hz
13000 Hz
4 MF
41040 5000 Hz
10000 Hz
3 MF
11937 7000
Hz 13000 Hz
Table 2:JBL Protection Capacitors for CompressionDrivers
NOTES:
1. The optimum value cited in Table 2 assumes that the
capacitor is active at approximately one octave below the
listed crossover frequency, assuring minimum acoustical
interference with crossover region performance while
maintaining a good degree of protection.
2. Somewhat smaller capacitor values may be required
for additional protection in high-power sound reinforcement
systems.
3. To shunt the reactive component of the compression
driver's impedance below horn cutoff, a 50 W resistor having
a value of two to three times the rated impedance of the
compression driver should be connected across the driver's
terminals.
CAUTION: Below the cutofffrequency ofthe capacitor,
thepoweramplifierwill be unterminated. Ifthe power
amplifierhas an outputtransformer(typical of vacuum
tubeamps and somesolidstateampsdesigned to drive
constant voltage lines), a 20W resistor equal toten times
the compression driverimpedanceshould be installed
across the amplifieroutputterminals.
8

SETUP & OPERATION
General Applications
When used for two-channelbiamplification, each
channel INPUT ofthe 5234A receives the full-range
programsignal from a linelevelsource such asa
preamplifier,mixingconsole or graphicequalizer.
Identical frequencyselectionmodules are installed
in both channels, andthe dividingnetwork separates
each ofthetwo channel'ssignals into high andlow
frequency bands. Each channel'sLOW and HIGH
outputsthenfeedindividualpoweramplifiers (or
discrete amplifier channels), which in turn drive
theirrespectiveloudspeakercomponents.
The 5234A also maybe used asa dividingnet-
work fora singlechannel of triamplification. In this
application, Channel 1 ofthe 5234A receives the
full-rangeprogram signal, and separates it into two
bands, one consisting oflowandmid frequencies,
theother of highfrequenciesonly. The Channel 1
HIGH output thenfeeds the amplifierwhichdrives
thehighfrequencydriver,while the Channel 1
LOW output (carrying lowandmid frequencies) is
connected tothe 5234A's Channel 2 INPUT. The
Channel 2 crossover point is chosen to fall inthe
regionwhere thelow frequencyloudspeaker's
operatingrangeends andthe midrangedriver's
operatingrangebegins.Therefore,Channel 2's
LOW output is suitable for feeding the amplifier
which drives thelow frequencyloudspeaker,while
its HIGH output is suitable for feeding the
amplifierwhichdrives the midrangedriver. In this
way, the CHANNEL 2 HIGH FREQUENCY
LEVEL controlbecomes a midrangedriverlevel
control andis independent ofthe CHANNEL 1
HIGH FREQUENCY LEVEL control,which
affects only the highfrequencydriver.*
As a convenience, the 5234A is supplied with
"blank" frequencydividingmodulesthathave
jumperresistorsinstalled in such a way that the
input signal is split andfedtothe channel's HIGH
and LOWoutputs. As such, the 5234Aoperates
as a fullybuffereddual distribution amplifier
(described inthe Installationsection of this
manual). Whilethis isnotthe primarypurpose of
the unit, the capability canbe usefulwhen itis
necessary to split a signal and driveseparatelines
and prevent any short or noisesource onone line
from causingproblems onthe other.
Typical Systems Employing the 5234A
Figures 12and13 illustrateconventionalloud-
speaker/amplifier systems for reference. Figures 14
through 17 depictvariousbiamplified andtri-
amplif Fed systems; theseshowtypicalexamples of
5234A applications,although byno means are they
all-inclusive. Figures 18 through 20 providewiring
details for typical systems.
*The frequencydivisioncould be donedifferently, with one chan-
nel handling the low-to-mid/high transition, and thatchannel's
HIGH output feeding the secondchannel,whichhandles the
mid-to-high transition. In that case, however, theHF LEVEL con-
trol ofthe firstchannelwouldaffect both the midrange and high
frequency drivers,while theHF LEVEL control ofthe second
channel wouldaffectonly the highfrequencydriver. The scheme
presented hereavoidsthisoverlapping of function,preserving
discrete control forthe midrange and highfrequencydrivers.
PROGRAM
SOURCE
LOUDSPEAKER SYSTEM
Figure 12— ConventionalTwo-Way System (Passive Network)
LOUDSPEAKER SYSTEM
Figure 13— ConventionalThree-Way System (Passive Network)
PROGRAM
SOURCE
PROGRAM
SOURCE
5234A
ACTIVE
FREQUENCY
DIVIDING
NETWORK
LOUDSPEAKER SYSTEM
Figure 14— DualChannelTwo-Way System (Biamplified)
9
ONE
AMPLIFIER
PASSIVE
FREQUENCY
DIVIDING
NETWORK
HIGH
LOW
PROGRAM
SOURCE
ONE
AMPLIFIER
PASSIVE
FREQUENCY
DIVIDING
NETWORKS
HIGH
MID
LOW
LOUDSPEAKER SYSTEM
FOUR
AMPLIFIERS
HF
LF
HF
LF
HIGH
LOW
HIGH
LOW
CHANNEL
CHANNEL
iissiiisiisi

PROGRAM
SOURCE
5234A
ACTIVE
FREQUENCY
DIVIDING
NETWORK
Figure15- Single ChannelThree-WaySystem (Triamplif ied)
(Duplicatethissetup fora stereothree-waysystem.)
FOUR
AMPLIFIERS
LOUDSPEAKER SYSTEM
ACTIVE
FREQUENCY
DIVIDING
NETWORK
FOUR
AMPLIFIERS
PROGRAM
SOURCE
PROGRAM
SOURCE
CHANNEL
2
5234A
ULTRA-HIGH
PASSIVE FREQUENCY
DIVIDING NETWORK
LOUDSPEAKER SYSTEM
PASSIVE
FREQUENCY
DIVIDING
NETWORK
SUBWOOFER
Figure 16— DualChannelTwo-WaySystem with Monaural
Subwoofer(s)
ACTIVE
FREQUENCY
DIVIDING
NETWORK
PASSIVE FREQUENCY
DIVIDING NETWORK
10
THREE
AMPLIFIERS
LOUDSPEAKER SYSTEM
LOUDSPEAKER SYSTEM
FULL
RANGE
HIGH
LOW
PASSIVE
FREQUENCY
DIVIDING
NETWORK
PROGRAM
SOURCE
Mono position
(#5) ONon both
DIPSwitches
SUBWOOFER
HIGH
MID
LOW
FULL
RANGE
5234A
PROGRAM
SOURCE
HIGH
LOW
Figure 17— CombiningElectronic & PassiveFrequency
DividingNetworks
LOUDSPEAKER SYSTEM
OPTIONAL SECOND SUBWOOFER
HIGH
MID
LOW
CHANNEL
llllllllll
ULTRA-HIGH
HIGH
MID
LOW