JBL Decade L36 User manual

L36 DECADE INSTRUCTION MANUAL

Excellence isanelusivequality.It'ssoeasyto
recognizeyetsodifficulttoattain.
JBL craftsmenhavebeeninvolvedintheartofsound
for more thana generation — signal andsource,wood
and fabric,transducersandacoustics —all ofit.
Today these craftsmencontinuetoperformtothe
most rigid standardsanycraftsmencansubmitto: those
theyimposeuponthemselves.
JBL loudspeakersarecarefullyengineered
instruments, painstakinglycraftedandassembledto
watchmakers' standards.JBLenclosuresexpressthe
excitement ofcreativedesign;theyareelegant, solid
and flawlessly finished. JBLtransducersandelectronics
offerwhathasbeencharacterizedbydevotedmusic
listeners asthe"incomparableJBLsound."
By followingthefewsimplesuggestionscontainedin
this booklet,youcanlookforwardtosuperbhigh
fidelity reproduction that will retainitsclarityand
realism year after year.
JBLcontinually engages in research related to productimprovement.New
materials, productionmethodsanddesignrefinements are introducedintoexisting
products without notice asa routineexpression of thatphilosophy.Forthisreason,
anycurrent JBL productmaydifferinsome respect from itspublisheddescription
but is alwayswarranted to equal or exceed theoriginaldesignspecificationsunless
otherwise stated.
INDF.X
Concept Of The Decade
1
PerformanceCharacteristics 2
Specifications 2
ConnectingThe L36
4
Listening RoomAcoustics 5
Placement 5
Adjusting TheSystem 6
Power Capacity 8
SystemComponents 9
ComponentRemoval
11
The Decade Enclosure 13
In Case Of Trouble 14
Service 16
Summary
16
ForAdditionalInformation 16

Seriousaudiophilesalwaysinsistonequipment
representingtheverylatestdevelopmentsinthehigh
fidelity arts.Andformostlisteners,theonly acceptable
loudspeakershave been theworld'sfinest:JBL.
However, thebuyerwhoenjoysmusicbutis limited toa
modestsumquiteoftenhas been settlingfor less —with
the expectationthateventuallyhe will tradeuptoa JBL
system.
For suchlisteners,therefore,JBLoffersthe Decade 36,
ano-compromiseloudspeakersystemoptimizingour
latestdevelopmentsina moderatesizedenclosure.
The Decade 36 achieves full, richperformance
utilizing a 10-inchlowfrequencyloudspeaker,5-inch
midrange transducerand1.4-inchhighfrequencydirect
radiator. EachcomponentoftheL36has been designed
to functionaspartofthecompletesystem,optimizing
performanceandefficiency without sacrificing
definition ortheabilitytoaccuratelyreproducethe
fleeting burstsofsonicenergy, known astransients,so
essentialtorealism.LikeallJBLloudspeakersystems,
the L36utilizesa portedenclosureto increase efficiency
and dynamicrange—incontrasttothe sealed "acoustic
suspension"enclosurewhich achieves apparent bass
CONCEPÌ'OF THEDECADE
1

response at the expense ofefficiency,dynamicrangeand
transient reproduction.Efficiency is importantfortwo
reasons:itpermitsuseof a relativelylowpower,
moderately pricedamplifier,anditallowstheamplifier
to operate ata lowerdistortionlevel,providingthe
reservepower necessary toachieve full dynamicrange
and excellenttransientreproduction.
The Decade 36 exhibitsthestrong bass, well defined
midrange andsparklinghighfrequencyreproduction
characteristicofallJBLloudspeakersystems.However,
the most striking characteristicofthesystem is its
exceptionalclarity.Modernrecordingscontainauditory
effects thatcanonly be capturedthroughthetechnology
•of electronicsappliedin a recordingstudioor ata live
performance—delicateovertonescapturedby close
microphone placementandcomplexharmonics
producedbyelectronicsynthesis.Suchstateoftheart
techniques,usedinbothcontemporaryand classical
recording, place rigorousdemandsoneventhemost
sophisticatedloudspeakersystems— demandsthatJBL
hasalwaysmetandsurpassed.
A numberofloudspeakersystemscanhandlelarge
amounts ofpower;othersarehighlyefficient.JBL
productsareuniqueintheirabilitytocombineboth
attributes. TheL36,forexample, will convert a 1-Watt
input of "white noise"1 into a soundpressurelevel
of 76 dBmeasured ata distanceof15feet.2This is
approximately twice as loud as ordinaryconversation
and represents a comfortablelisteninglevel,
demonstrating thattheL36deliverssubstantialsound
output from very little inputpower.
Ratherthanrepeattheambiguityofmosttechnical
specifications,JBLhas traditionally refrained from
listing dataforwhichnowidely accepted testprocedure
hasbeenestablished.Inthe absence ofsuchstandards,
any well equippedlaboratorycanlegitimatelyproduce a
variety offrequencyresponsecurvesfor a loudspeaker,
1. "White noise" is a rigorous test simulating average musical
program material under laboratory conditions. It provides a
controlled means of energizing all the transducers of a
loudspeaker system simultaneously. "White noise"
encompasses all audible frequencies just as white light
includes all the colors of the visible spectrum. Produced in
the laboratory by a signal generator, "white noise" sounds
very much like the hiss heard between FM radio stations.
2. A decibel (dB), in this context, is a unit expressing relative
loudness of sound. Three dB is approximately equal to the
smallest change in loudness of program material ordinarily
detectable by the human ear.
2
PERFORMANCE
CHARACTERISTICS
SPECIFICATIONS

dependingontheconditionsselected.AtJBLthe final
analysesarecomprised of extensivelisteningsessions.
Although laboratorydataare an integralpart of the
process, thetrainedear is theultimatecriterion.The
success of thisphilosophy is reflectedintheenthusiastic
acceptance of JBLsystems by recordingstudio
engineers,producersandperformers—professionals
whoseartisticachievementsarecloselyrelated to the
equipmenttheyuse.
Power Capacity1 50 Wattscontinuousprogram
Nominal Impedance 8ohms
Dispersion 90° horizontalandvertical
CrossoverFrequencies 1500and 6000 Hz
Efficiency 1 Watt input produces 76dB
SoundPressureLevel ata distance of 15'
(Note: 75-80 dB is a comfortable listening level.)
Low FrequencyLoudspeaker
Nominal Diameter 10inches 25cm
Voice Coil 2-inch (5 cm)copper
MagneticAssemblyWeight 2Vi pounds1.1 kg
Flux Density 8500 gauss
Sensitivity2
40 dB
Midrange Transducer
Nominal Diameter 5inches
13cm
Voice Coil
%-inch (2.2cm)copper
MagneticAssemblyWeight l5/8pounds0.7kg
Flux Density
15,000 gauss
Sensitivity Averaged1-3 kHz. 45
dB
High FrequencyDirectRadiator
Nominal Diameter 1.4inches
3.6cm
Voice Coil
5/8-inch(1.6cm)copper
MagneticAssemblyWeight 1% pounds0.7kg
Flux Density
15,000 gauss
Sensitivity Averagedabove 2 kHz.
41 dB
Finish
Natural Oak
Grille
Stretchfabric
Grille ColorOptions Orange,Blue
or Brown
Dimensions 131/2"x24"xl35/8"deep
34x61x35 cm deep
Shipping Weight 45lbs
20 kg
1. Basedona laboratory test signal.SeePowerCapacitysectionforamplifierpower
recommendation.
2.Sincethemajorportionoftheenergyreproducedbythelowfrequency
loudspeakerliesbelow800Hz,thisspecificationhasbeendevelopedusinga test
signal warbledfrom100to500Hz, rather thanthe1-kHzsinewave test signalon
which theconventionalEIAsensitivityisbased.
3

IMPORTANT: Whenconnectingordisconnecting
loudspeakers from anamplifier,theamplifiermust be
turned off. Making connections while theamplifier is
operating couldseriouslydamagetheloudspeaker
system and void the warranty.
Eighteen-gaugeinsulated wire (ordinaryhousehold
lampcord) is the minimum sizerecommendedfor
loudspeakerconnectionsupto 50 feet.Beyondthis
distance,heaviergaugeinsulated wire is recommended;
16-gauge from 50 to100feetand 14-gauge from 100to200
feet.Iflampcord is used,wirescan be differentiatedby
noting thatoneoftheinsulatingjackets is smooth, while
the otherhas a distinctridge.Byconsideringtheridged
jacket"red"andthesmoothjacket"black," wiring
connectionscan be made as ifusingcolor-coded wire.
Connectionstotheaudiopowersourcearemade
using thetwopushbutton terminal postslocatedonthe
back oftheloudspeakersystemenclosure.Theholesin
JBL terminal postsdonot allow theconnecting wire to
pass allthewaythrough,preventingthepossibilityof a
short totheother terminal postortonearbyelectrical
conductors.
To make a secure connection,stripapproximately %
inch ofthe insulation from theendofthe wire, push
down thespring-loaded terminal postcap,insertthe
bare wire into theexposedopeningofthe terminal post
and release.(Insertionofthe wire into theopening will
beeasierifthestripped wire is first tinned with a
soldering tool andsolder.)
Locatetheloudspeakeroutputterminalsonthe back
of thereceiverorpoweramplifier.For each loudspeaker
system, connectthe wire from theblack terminal postto
the amplifieroutput terminal labeled"common,"
"ground" or(—),andthe wire from thered terminal post
to theremaining8-ohmspeakeroutput?
Note thatmanyamplifiershave a chassis grounding
terminal which is usuallyisolated from theother
connectors.Thisshouldnot be confused with the
"ground" designationsometimesusedtodescribetwo
of theterminalsin each setofloudspeakerconnections.
3. Connecting both speakers as described will insure proper
"in phase" operation; i.e., their cones will respond to a
monophonic signal by moving simultaneously in the same
direction, and not opposite to each other. Inadvertent out-of-
phase operation (which occurs when one set of speaker
wires is reversed with respect to the other) will not harm the
system, but may cause some acoustical "cancellation" which
will have the audible effect of reducing low frequency
response.
4
CONNECTING THEL36

The specified8-ohmimpedancerating isa nominal
figure which suggests a connectiongivingthemost
efficient powertransferbetweenamplifierand
loudspeakersystem.However, 4- or16-ohmamplifier
terminals can be used without danger.
The soundreflectingorsoundabsorbingqualities of
the listeningroom will affectthesoundqualityof a
loudspeakersystem.Room acoustics can be testedby
listening tothe echo of a sharpsound,such as hand
clapping.
A roomhavinglargewindows,paneledwallsand a
hardwood floororceiling will be acoustically "live" and
will echo noticeably. A roomcontainingoverstuffed
furniture, carpetedfloorsordrapedwindows will be
acoustically"dead"and will echo very little ornot at all.
Ideally, thereshould bea reasonable balance between
absorptivematerialandsoundreflectingsurfaces. If
therearetwolargereflecting surfaces facing each other,
the "bounce"betweenthem will makesoundsrun
togetherandthemusic will lack definition. Large, flat
wall surfaces should be brokenup with bookshelves,
drapesor screens.
Although JBLloudspeakershave a widesound
dispersion pattern,the final soundofthecompleted
installation is affectedbythelocationoftheenclosure
within thelisteningenvironment.Ifpossible,experiment
with placementof each loudspeakersystembefore
decidingon a final arrangement.
For the best possiblestereoperformance,thetwo
loudspeakersystemsshould be arrangedsymmetrically
on each sideofthelistener.As a general rule, a person
sitting intheusuallisteningpositionshouldseeanangle
5
LISTENING
ROOM ACOUSTICS
PLACEMENT
1. Depress colored button, exposing hole in terminal post.
2. Push stripped end of lead wire into hole and release
button. Never apply twisting force to the terminal post.

of about 40° betweenthetwosoundsources.The
distance from oneloudspeakerenclosuretotheother is
determined bytheirdistance from thelistenerandby
the 40° "listeningangle."
Loudspeakersmaybepositioned at anyheightabove
the floor,althoughlocatingthehighfrequencydirect
radiator nearearlevelusuallygivesthemostrealistic
suggestionof a live performance. Bass response will
beaugmentediftheenclosuresareplacednearadjacent
room surfaces,such as in a corneroron a wall nearthe
floor orceiling.
The L36 is provided with a Presence controlto
regulatetherelativeloudnessofthemidrange
transducerand a Brilliancecontroltoadjustthevolume
of levelofthehighfrequencydirectradiator.These
controls adjusttheoutputofthecomponent
loudspeakerstoachieverealistictonal balance in a
variety ofroomconditions.
The controlsarecalibratedintermsof a referencelevel,
indicated by a "0"ontheinstructionplate.Whenboth
the Presence andBrilliancecontrolsaresetatthislevel,
the loudspeakersystem will be adjustedforbalanced
6
LOUD- '
SPEAKER
LOUD-
SPEAKER
ADJUSTING THESYSTEM
40° "Listening Angle"
Sound energy from each loudspeaker blends to form a
stereo "wall of sound." The stereo image will be intensified
and the area of best stereo perception increased if the two
systems are rotated slightly toward the preferred listening
position.

performancecharacteristicsin a reverberation-free
environment. Sincemostlisteningrooms possess
varying degrees ofreverberation,someadjustment of
thecontrols is usuallypreferred.
Theloudspeakersystemshould be adjustedwhile
reproducingnormalprogrammaterial with the
amplifier tonecontrolsset at themiddle(generally
referredto as "flat")position.Beginbyplacingboth of
theloudspeakersystemcontrols at thereferencelevel
andlisteningto a varietyofprogrammateriallong
enoughto become accustomedtothesystem's
performance.
After theearhas become attunedtothe"0"setting,
evaluatethe presence andbrilliancequalitiesofthe
loudspeaker'sperformance.Themostvalidevaluation
will be obtainedusingvarioustypesofmaterialplayed
monaurally. (Thiscan be accomplishedinstereo or
quadraphonicinstallationsbysettingtheamplifiermode
control formonauralreproductionandusingthebalance
control to select theindividualloudspeakersystemto be
adjusted.)Theevaluationshould be madewhileseated
in thenormallisteningposition.
To arrive at thespecificsettingfor each ofthe
loudspeakersystemcontrols,proceed as follows:
1. Setthe Presence control at"0" androtatethe
Brilliance controltotheextremeleftofitstravel.This
will attenuatehighfrequencyperformance so thatthe
ear will perceiveonlythebalancebetweenthelow
frequencyloudspeakerandthemidrangetransducer.
2.Ifmidrangematerial—such as violin, piano, or
guitar —seems too close oroveremphasized,reducethe
setting ofthe Presence controlbyrotatingittotheleft.
Conversely,ifmidrangematerial seems toodistant,
increasetheoutputofthemidrangetransducerby
rotating thecontrolclockwise.
7
Presence and Brilliance controls are conveniently located
on the front of the enclosure, behind the removable grille
assembly.

3.Oncethe Presence controlhasbeenadjustedto
provide themostpleasingbalancebetweenthelow
frequencyandmidrangetransducers,settheBrilliance
control at"0." Ifhighfrequencymaterial—such as
cymbals,bells,triangles, violin overtonesorvocal
sibilants —seemtooprominent,lowerthesettingof
the Brilliancecontrol.Ifgreaterhighfrequencyoutput
is desired,increasethesettingofthecontrol.
After each setofadjustments,againlistento a variety
of programmaterial until theearhas become attuned
to thenewcharacteristicsandcancomparethemtothe
previous performanceofthesystem.Oncethe Presence
and Brilliancecontrolshavebeensetforthemost
pleasingoverallresults,andthe exact placementof
•each loudspeakerhasbeendetermined,compensation
for differencesin individual recordingsshould be
made with thetonecontrolsontheamplifierorreceiver.
The specifiedpowercapacityindicatesthecontinuous
program powerlevelthatcan be accepted by a JBL
loudspeakersystem without damage.Itspeakpower
capacityisconsiderablygreaterthanthecontinuous
rated value, as indicatedbytheremarkabletransient
responseofJBLloudspeakersystemcomponents.The
Decade 36 will reproducecleansoundatcomfortable
listening levelswhendrivenbyanamplifierhavingan
output ofas little as 10WattsRMSperchannel.4
However, forreproductionofthe full dynamicrange
of contemporaryrecordingsathighvolume, a quality
amplifier deliveringupto100WattsRMSperchannel
will provide optimum performance.Innormalhigh
fidelity applicationsanamplifiershouldnever be
operated with itsvolumecontrolatmaximum,yet
suchanamplifierhasthereservepower necessary for
accuratereproductionoftransients,whichcanreach
momentary peaksequivalenttotentimestheaverage
power level.
If distortion is heard,oneormoreofthesoundsystem
components is operatingbeyonditscapacity(assuming
each componentisproperlyadjusted)andtheoverall
volume levelofthesoundsystemshould be reduced.
In almostall cases, theacousticlevelgeneratedby a
JBLloudspeaker will become noticeablydiscomforting
to theearbeforetheloudspeakercan be damagedby
excessive power from theamplifier.There is virtually
4. The RMS (root mean square) rating of amplifier power
is the most stringent method currently used in the audio
industry. An amplifier rated at 60 Watts RMS per channel,
for example, is generally considered to be a high-powered
unit. The same output expressed in terms of "Music Power"
would be 160 Watts.
8
PO\ vEkCAPACITY

no clanger of damaging a JBL loudspeaker ifitis
operated within the following guidelines:
1) the signal from the amplifier,regardless of its
rated power, is not distorted; 2) the amplifier is not
driven into clipping(another form of distortionwhich
occurs when the poweroutputlimitations of the
amplifier circuitry are exceeded); and 3) the power
cord or audioconnectors arenot inserted or unplugged
while the amplifier is operating.
However, a powerful widerangeamplifier can
accidentlydamage any loudspeakerundercertain
conditions. For example,rewinding a taperecorder with
the playbackvolumeturned up can generate"squeals"
powerful enough to burn outthe highfrequency unit.
Similarly, powerful low frequencypulsesextending
down into the subsonicrange can eventuallydamage
the low frequencyloudspeaker. If the phonograph
pickup is accidentallydropped with the volumecontrol
full up, orif the system is playedvery loudly with
excessive bass boost,nearly the full ratedpower of the
amplifier can be channeled into dangeroussubsonic
energy.
The componentsused in every JBL product are
designed and produced by JBL personnel to exacting
standards. JBL loudspeakerframes are massive rigid
structures. Magnetic assemblies are precisely
manufactured of low-reluctance iron, energized by large,
high grademagnets.Voicecoils are held to within
one turn of designspecifications.Stampedframes,
punchedmagneticstructures and mass-producedvoice
coils would be less expensive;however, the resultant
loss of structuralintegrity,magneticforce and acoustic
efficiency would tend to degrade low-distortion
performance and transientresponse—qualitiesthathave
become JBL hallmarks.
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detiivirirr h^ivrp^n "che ^VK° > nil aii*. liiugn*^ ^ca^Ttihjy
li :>n> linai! thai rti.y Pn^m^i In mr>\'^ a cnia^- ini*j:ui!dliv'
'J<n{
0-J.f;Ih
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LOW FREQUENCY-Solid, well-defined bass
reproduction is provided bya 10-inchlong-throw
loudspeaker. Its 2%-poundlow-lossmagneticassembly
concentrates allthe energy ofan Alnico V magnet inthe
one place where it contributes to performance — the voice
coil gap.The copper voicecoil, two inches in diameter,
drives an integrallystiffened cone. Thislargecoil,
interacting with the magnetic field, provides the
mechanicaldrive necessary for instantaneoustransient
reproduction. Mass and stiffness of the cone havebeen
carefully selected to provide optimum low frequency
bandwidth and definition. The cone is contained within
9
SYSTEM COMPONENTS

asturdy, cast aluminum frameandsuspended at its
outer edge bya highlyflexible ring to absorbextraneous
sound wavesandallowthelongexcursion necessary
to achievedynamicrangeandextend bass response.
MIDRANGE — The Decade 36 exhibits the midrange
presence that is characteristic of all JBL systems. Presence
creates the feelingthat a performance is takingplace
in front of the enclosure,ratherthancoming from
within it.The5-inchmidrangetransducer is notedfor
peak-freeperformanceand uniform sounddistribution,
both on-andoff-axis. Its lightweight,curvilinear cone
is driven bya %-inchdiametercoppervoicecoil
suspended within the strong field generated bya
1%-pound magneticassembly.Theouter edge of the
cone is treated with an exclusiveviscous formulation
that absorbs extraneoussoundwavestravelingthrough
the materialandeliminatesfatigue. A metalliccenter
domecontributes to smoothperformance in the unit's
upperregion.
HIGH FREQUENCY-Overtones lying above the
range of musicalfundamentals are reproduced by the
1.4-inchhighfrequencydirectradiator. It utilizes a
%-inch diametercoppervoicecoilandl5/s-pound
magneticassembly.Thevoicecoil is large in relation
to cone diameterforefficiencyandtransient
reproduction with definition andaccuracy.Thesmall
diameter of the cone andcenterdomespreadssound
in a widepattern,assuringthat each listenerhears the
sametonalbalanceandblend of directandreflected
sound, regardless of position within the prescribed
listening area.Theentiredynamicassembly is
surrounded bya ring of densefoamdampingmaterial
to absorbunwantedradiationandreflections.
DIVIDING NETWORK-Smooth,imperceptible
control of theloudspeakersystemcomponents is
achieved bya frequency dividing networkcarefully
engineeredandtested to complement the specific
electricalandacousticcharacteristics of thesystem.
The function ofa precision dividing network is
considerablymore'complexthanmerelyfeedinglow,
midrange andhighfrequencies to theirrespective
transducers. Vitally important to the total sound ofa
JBLloudspeakersystem is the waythenetwork
distributes electricalenergyfor optimum control of the
systemcomponentsthrough the transitionfrequencies.
JBLnetworkcomponenttolerances are muchmore
stringent thannormalindustrypractices.Forexample,
the capacitorsused are non-inductive,non-polarized
types with high AC currentcapacity built expresslyfor
use in dividing networksand individually testedfor
conformity to rigid performancestandards.Thespecial
10

inductors haveextremelylowinsertionloss so thatnone
of the driving power tothe loudspeakersystem is
dissipated inthe network.Eachinductor is calibrated
on a sensitiveelectronicbridge andits value set
precisely.
The dividing network is provided with Brilliance and
Presence controlswhichallowbalancingloudness of
the midrange and highfrequencydrivers to satisfy
listening room acoustics and personalpreference. The
dividing networkcontrols donot appreciablyaffect the
crossoverfrequencies, nordo they limit the upper
frequencyresponse ofthe loudspeakersystem.
If it should be necessary to remove the loudspeaker
systemcomponents for testing or repair,disconnect the
loudspeakersystem from the amplifier and proceed as
follows:
GRILLE — Thegrille is secured tothe enclosure by
dowel pinslocatednear the fourcorners of the assembly.
It can be removed by graspingboth topor bothbottom
corners and gently lifting the assemblyaway from the
enclosure. To replace the grille, reposition itonthe
enclosure and applylightpressure at the corners until
the assembly is fully seated onthe dowelpins.Notethat
one of the dowelpins is offset to insurethat the grille
canonly be replacedwhenpositionedproperly. TheJBL
emblem can be rotated to readcorrectlywhether the
loudspeakersystem is placedhorizontally or vertically.
LOW FREQUENCY-Place the enclosure onits back
on a clean,paddedsurface. The lowfrequency
loudspeaker is mounted from the front ofthe baffle
panel and held in place by fourPhillips-headscrews
threaded into T-nutfastenerswhich are anchored onthe
back of the panel.Carefullyunscrew the machinescrews
11
Loudspeaker System Components
10-inch Low Frequency Loudspeaker
5-inch Midrange Transducer
1.4-inch High Frequency Direct Radiator
COMPONENT REMOVA I.

without applyingpressurethatmightdislodge the
T-nuts. When the mounting screwshavebeenremoved,
gently lift the edge of the loudspeakerframe from the
baffle panel,disconnect the wires at the tab connectors
on the loudspeakerframe and remove the unit from the
enclosure. The sealinggasketshould be reused when
the unit is replaced.
MIDRANGE AND HIGH FREQUENCY-The midrange
and high frequencyunits are each held in place by
four self-tappingscrews at each corner of the frame.
Carefully remove the screws, lift the unit from the
enclosure and disconnect the wires at the tab connectors.
The fibergasketbeneath the high frequencydirect
radiator should be reused when the unit is replaced.
•DIVIDING NETWORK -The dividing network is
installed behind the bafflepanel and is held in place by
four machinescrews. To gain access tothe network,
remove the transducers as previouslydescribed,
carefully pull the wire leads from the midrange
sub-chamber,disconnect the input leads from thetab
connectors at the back of the enclosure,remove the four
mounting screws and lift the network out through the
low frequencyloudspeakeropening.
WIRING — Whenreconnecting the wiresbetween the
dividing network and the componentloudspeakers,
proper polarity is assured bythe connectors. The wires
arecolorcoded as shownbelow.

REPLACEMENT— Reverse the removalprocedure to
replace the loudspeakersystemcomponents.Mounting
screwsshould be tightenedevenly to avoid the
possibility of framewarpage,andjustenough to
prevent airleaksbetween the componentsand the
enclosure. Avoid excessive force.
Although JBL loudspeakers are extremely ragged, the
cone andothermovingparts are subject to accidental
damage. Exercise extreme cautionwhenusing a
screwdriver or othertools in their immediate vicinity.
The Decade 36 enclosure,embodying the advanced
principles of fine furniture designandconstructionthat
havemade JBL leader of theindustry,complements the
acousticcharacteristics of the loudspeakersystem. It
utilizes a ductedportextendingthrough the baffle
panel to restrict air flow, providing the properload on
the loudspeaker cone forimprovedefficiency and
dynamic range. To achievemaximumstrength and
resistance to vibration,allpanels are constructed of
3/4-inch
stock;sideand back panels are lined with
acousticpadding; and alljoints are hand fitted, lock
mitered andwoodwelded.
The continuoussearchforrefreshingvisual approaches
led JBLto pioneer theuseof newfinishes—inthis case
natural oak.Thebeauty of itslighttone and distinctive
grain structure is broughtout bya hand-rubbedoiled
finish. Thecontrastbetween the richcolor accent
provided by the contemporarygrilleand the natural
finish reflects the mostrecentinternationaldesign
trends, suggestingthattheL36 will become an important
decorativeelement in anylisteningroom.
The grillecloth isa double knit polyesterfabric
selected foracoustictransparency,beauty,physical
strength, color fastness and soilresistance. Itcan be
cleaned by gentlydusting it with a vacuumcleaner.
Stains can be removed by usingaerosolcleaners,such
asTexize K2r, Goddard'sDry Clean, or PenChamp
Quick 'n Easy, according to each manufacturer's
instructions.
Warning: Cleaningfluids or othersolventsshouldnot
beused. Although theymayappear to remove a stain,
liquid cleaners will dissolvethe base paint onthe grille
frame beneath the cloth,resulting in permanent
discoloration of the material.
Occasionaldusting with a clean,softcloth will
maintain the originalbeauty of the oak finish. Since
moisture cannotpenetrate the oiledsurface,most
household stains can be removed with a dampcloth.
13
THE DECADEENCLOSURE

Thesurfaceshouldbetreatedonly with waxspecifically
formulated foruseonoiledfinishes.Conventional
furniture waxes,polishesor cleaners arenot
recommended.
As theoilpenetrates deeper and deeper intotheoak,
thefinishmayappeartobedryingout.Manyowners
find itdesirabletore-oiltheenclosuresurface from time
to time. With each application,thebeautyofthefinish
will become moreapparentanda warm,richpatina will
eventually beobtained.
To re-oila JBLfinish,useanyoneoftheseveral clear
oil finishingpreparationsavailablethroughfurniture
orhardwareoutlets.Applya liberalamountofthe
preparationovertheentirefinishedsurfaceofthe
enclosure.Intentofifteenminuteswipeoffthe
remaining oil with a soft,clean,drycloth.Small
surface scratches canusuallyberemovedbygently
rubbingthemout with veryfinesteelwool(4/0grade)
andapplyingoiltotheentirepanel.Whenusingsteel
wool, applylightpressureandrubonlyinthedirection
ofthegrain.Very deep scratches, dentsorother
seriousdamageshouldberepairedonlybya qualified
furniture refinisher.
Caution: Improperstorageofwipingragscouldresult
in spontaneouscombustion.Theyshouldbethrown
awayorspreadouttodryina well-ventilatedarea
beforestorageordisposal.
A JBLloudspeakersystemresponds with verbatim
accuracy tothesignalsuppliedbytheaudiopower
source;it will thereforereproduceextraneousnoisesjust
asaccuratelyasitreproducesdesiredprogram
material. Noiseseldomoriginatesintheloudspeaker
system.Its presence usuallyindicatesthatoneofthe
othercomponentsofthemusicsystem,ortheprogram
material itself,isfaulty.Inrareinstanceswhen
something does gowrong with theloudspeakersystem,
oneormoreofthecomponentloudspeakers will stop
working altogetherora distinctrattlingorscraping
sound(indicatinga rubbingvoicecoil) will beheard
wheneverthesystemisoperating.
If onechannelofa stereoinstallationisnot
operating,examinetheloudspeaker wiring and check
the balance control.If wiring instructionswerefollowed
correctly,iftheconnectionsarecleanandtight,andif
centeringthe balance control does notremedythe
situation, reversetherightandleftloudspeaker
connectionsattheamplifier,taking care to turn the
amplifier offbefore each connectionordisconnection.
14
IN CASE OFTROUBLE

If thepreviouslynon-functionalloudspeakersystem
operates,theamplifieroroneofthecomponentprogram
sources (tuner,phono,tape deck, etc.)ismalfunctioning.
In theeventthatthe suspect loudspeakersystemis
still inoperative,itisprobablydefective.
To determinewhetherthe defect liesintheamplifier
or inoneofthecomponentprogram sources (after
verifying thattheloudspeakersystemsarenotdefective)
reversetherightandleft cables from theprogramsource
attheamplifier.Iftheoriginalchannelis still
inoperative, theamplifierisdefective;ifthepreviously
inoperative channelfunctions,theprogramsourceis
defective.Iftheamplifierisnot faulty, alternately check
each programsource until thedefective unit hasbeen
isolated. Itis unlikely thatmorethanoneprogram
source will be faulty atanygiventime.
Extraneousinterferencesuchasstaticorradio
broadcast signalscanbepickedupbythecomponent
devices.Whenthisoccurs,thetroublesome unit can
beidentifiedbydisconnectinginputs from the
receiveroramplifier until theinterferencestops.Again,
if theinterferencepersists with noneoftheinput
devicesoperatingthroughthepowersource,thereceiver
or amplifieritselfisprobablydefective.Shortingplugs,
available from yourJBL Audio Specialist,shouldbe
inserted inunusedphonoinputstohelpeliminate
stray humorsignalpickup.
Fuzzy orindistincthighpitchedsoundscanusually
betracedtotherecordingitself,a defectivecartridge,
a worn stylusorinsufficienttrackingforce.Problems
with lowfrequencyreproductionareusuallytheresult
of room acoustics orplacementofthe speaker system.
Excessive bass boostorincorrectloudnesscompensation
tend togivea muddyor"boomy"qualitytoreproduced
music. Themusicsystemcanbe checked forturntable
rumble orotherextraneouslowfrequencysignalsby
removing theloudspeakergrilleassemblyandobserving
the motion ofthelowfrequency cone while thesystem
is playingathighvolume.Ifthe cone continually
movesinandoutmorethanV2 inchorso, excessive
low frequencypowerisbeingfedtotheloudspeaker
system.
Hum maybe caused bylocatinga turntableortape
recorderdirectlyoverorunderneaththeamplifieror
receiver.Thefarthertheaudiopowersourceislocated
from thephonographcartridgeortapeheads,the less
chance there will beofpickinguphum.TheACleads
and shielded cables shouldbeaswidelyseparatedas
possible;AClinesshouldnever cross cables or
15

speaker wiring. Powerlineinterferencecanbefurther
attenuatedbyusinga heavydutylineinterference
filter betweentheaudiopowersourceandtheAC
wall outlet.
Acousticfeedbackistheresultofmechanical
vibrations producedby excessive bass atveryhigh
volume levels.Theloudspeakersystemcanproduce
enough energytovibrateother objects intheroom—
including therecordplayerand,bydirectmechanical
transmission, thestylusitself.Thesevibrationsare
amplified againandagain,producingveryloud
"rumble," orevena sustained howl that increases in
intensity asthevolumeor bass controlisturnedup.
Possiblesolutions:1)locatethespeakercabinetsasfar
aspossible from theturntable,2)adjustorreplacethe
turntable shockmountings,3)placetheturntableona
rubberorspongemattofurtherabsorbvibrations.If
the lowfrequencytoneis still audible,itisprobably
the resultofinherentturntablerumbleratherthan
acousticfeedback.
Should yourJBLloudspeakersystemrequireservice,
return ittotheJBLdealer from whom itwaspurchased.
If itisnotpossibletocontacta dealer, write directly
to theJBLServiceDepartmentdescribingthe difficulty
as fully aspossible.Productsreturnedtothefactorymust
besentprepaidand will notbe accepted unless written
authorization has first beenobtained.Thewarranty
is recognizedonlywhenthe unit isrepairedbyJBL
or anauthorizedJBLServiceAgencyandiftheserial
number ofthe unit hasnotbeendefacedorremoved.
In additiontotheestablishedfive-yearwarranty,JBL
will, atitsoption,repairthespeakersfreeofcharge
during theirentirenormal life iffactoryinspection
disclosesanoriginalmanufacturingdefect.Toestablish
the warranty, fill outand mail thewarrantycard within
ten daysofpurchase.
The Decade 36exemplifies JBL's reputationfor
leadershipinacousticandvisualdesign.Itisoursincere
beliefthattheL36 —like allJBLproducts— will provide
undiminished listeningpleasureformanyyearstocome.
If youhave difficulty inachievingthefine
performanceofwhichyourJBLloudspeakersystemis
capable,consulttheJBL Audio Specialist from whom
the systemwaspurchased.Heisequipped with the
knowledge requiredtoprovideexpertadviceand
assistance. IfforsomereasontheJBLdealerisunable
to assistyou, write directlytotheJBLTechnical
Information Departmentexplainingthe difficulty in
detail.
16
:r /iCf
FOR ADDITIONAL
INFORMATION

James B. LansingSound,Inc., 3249 Casitas Avenue,LosAngeles,California 90039.
50663OM36/74PrintedinU.S.A.
jbl