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