JBL N500 User manual

JBL
DIVIDINGNETWORK
INSTRUCTIONMANUAL
JBL
PUBLICATIONOM22-3

James B. Lansing Sound, Inc. maintains a Tech-
nical Service Department, to help JBL owners with
their individual problems. If you cannot find the
answer you need in published JBL literature or
obtain it from your Audio Specialist, please
write us.
All JBL precision transducers are fully guaran-
teed against defects in materials and workman-
ship. Be sure to fill out and mail the warranty card
immediately.
APPLICATION
JBL precision networks usecircuitscarefullyde-
signed to give an imperceptible transitionfrom
low tohigh frequency transducers. Unlike ordinary
all-purpose networks, each JBLcircuitisspecifi-
cally engineered to match the characteristics of
theJBL transducers with whichitis used, and
should notbe connected to components forwhich
it isnot designed. Components which match each
of theJBLdividing networks arelistedinthe
table below:
NETWORK
MODEL CROSSOVER
FREQUENCY LOW
FREQUENCY
TRANSDUCER
HIGH
FREQUENCY
TRANSDUCER
HIGH
FREQUENCY
CONTROL
INPUT
IMPEDANCE
(OHMS)
SHIPPING
WEIGHT
(LBS.)
N500 500 150-4's
150-4C 375 Strapping
Bar 16 16
LX5 500 LE15A
375, LE175,
LE85
3-position
switch 8 10
LX7 500 LE14A LEI75
3-position
switch 8 10
N1200 1200
0130, D131,
130A,130B's LE175
3-position
switch 8 9
LX10 1500 LE14A LE175 Continuously
variable 8 3
LX8 2000 LE14A LE20
3-position
switch 8 3
LX11 2500 LE10A LE20
3-position
switch 8 3
LX2 2500
D123, D208,
D216 LE20 Continuously
variable 8 3
N2400 2500
D130, 0131,
D123 075 Continuously
variable 8 4
N7000 7000 Anytwo-way
system 075 Continuously
variable 4to16 3

SOPHISTICATED CIRCUITRY
Dividing networksareusedintwo-way loud-
speaker systemstoelectricallychannellow tones
to the bass loudspeakerand high notes andover-
tones tothe high frequencytransducer.
If a dividing networkisto fulfill its function with-
out compromise,itmustbeabletohandleextreme
variations indynamics,the full rangeofaudio
frequencies,complextransients,andthe varying
impedanceofa loudspeakerload.
JBL dividing networksare carefully designedto
complementtheexactcharacteristicsoftheJBL
transducers with which theyaretobeused.Each
network circuit controlsthesignaltothe high
andlowfrequencytransducersinsucha waythat
smooth acoustic response ismaintainedthrough
the full audiospectrum.Thus,theeffectsof indi-
vidual speaker characteristics,impedance fluctua-
tions, andthephysicalseparationofthetwosound
sources arealltaken into accountinthecomplete
systemdesign.
Naturally, suchsophisticatedengineeringde-
mandsveryclosetolerancesinproductionifallthe
benefitsofthedesignapproacharetoberealized.
Ordinary networks,forexample,oftenuseelectro-
lytic capacitors with tolerancesofplusorminus
20%. Response throughthecrossoverregionis
ragged,andcharacteristicsvary from unit to unit.
All JBLnetworks,ontheotherhand,use only non-
inductive paperormylardielectriccapacitors(not
electrolytic units) individually testedtomeetJBL
tolerances.ThespecialinductorsusedinJBLnet-
works haveextremelylowinsertionlosssothat
noneofthe driving powertotheloudspeaker
systemiswastedinthenetwork.Eachinductor
is calibratedona sensitiveelectronicbridgeand
its valuesetprecisely.TomeetJBLproduction
tolerances,networkcomponentsmustcheckout
within plusorminus1%oftheestablisheddesign
value.

MOUNTINGINJBL ENCLOSURES
JBL dividing networksarenormallyinstalledin
thebackpaneloftheloudspeakerenclosure.In
JBL enclosures,theymaybeeasilyinstalleddi-
rectly intothemountinghole which isprovided.
Make sure thatthewhitetubular gasket isinplace
aroundthenetworkflange.Centerthenetwork
into themountingholeand secure by driving four
#6x %"round head wood screws intotheoutside
surfaceofthepanel.(To install the LX4-2 net-
work intothestandardcutout,theF2mounting
flange isrequired.)
MOUNTINGIN CUSTOM ENCLOSURES
Dimensionsfortherequiredmountingholeare
showninthediagram.(Tomountthe LX4-2 in
acutoutofthissize,theF2mountingflange is
required.)
If youmountthenetworkinthe same compart-
mentasthelowfrequencydriver,make sure that
themountingholeiscutexactly.Otherwise,the
white tubularmounting gasket will not seal prop-
erly, andtheresultingairleaksmayintroduce
objectionable hisses andwhistlesintothesystem.

ADJUSTING HIGH FREQUENCY GAIN
Since thehighfrequencycharacteristicsofrooms
cannot bepredicted, each JBL dividing network
isprovided with a highfrequencylevelcontrol,
which makes itpossibleto achieve a realistictonal
. balance under a varietyofroomconditions.The
acoustics ofyourlisteningroomandyourpersonal
listening taste will dictatethesettingwhich will
providethemostpleasingperformance.
Thecontrol enables youtoadjustthepowerfedto
thehighfrequency transducer. It does notaffect
the crossover frequency,nor does it limit the upper
frequency response ofthe loudspeaker system.
Some experimentation with thiscontrolisusually
necessary whenthe system is first installedinits
permanent location.Ifmusicalreproduction seems
tobe shrill andedgy,turnthecontrolcounterclock-
wisetoa lowersetting.Ifit seems dead and dull,
turn clockwisetoa highersetting.Comparative
listening tests shouldbe made attheusuallisten-
ing location. Once thecontrolissetfor best overall
results,it need notbe changed. Youcancompen-
sate foradditionaldifferencesin source material
with yourpreamplifiercontrols.
THE MODELN500
TheJBLN500 dividing networkisa professional
unit designed primarilyfor theater installations.
It isusuallymountedontopofthe enclosure or
in some othervisibleandconvenientlocation.
All terminal screws lying onthewhitelineare
common.Theoutput screws onthislineshouldbe
connected totheblack speaker terminals.Thetwo
screws marked"LF"areinternally connected so
thatconnectinganLFdriverto each setof posts
effectively connects thedriversinparallel.
Thegainofthehighfrequencyunitmaybe
adjustedbychangingthepositionofthestrapping
bar.Zeropositionprovidesthemaximumintensity
level oftheHFunit.Each successive step lowers
theHFlevelonedb.

CONNECTING JBL NETWORKS
NETWORK IMPEDANCE All JBL dividing net-
works arematchedtothecharacteristicimpedance
of the transducers with which theyare used. Model
N500 isa 16-ohmnetworkandshouldbeconnected
to the16-ohmamplifiertapformostefficientpower
transfer.AllotherJBLnetworks will operate most
efficiently whenconnectedtothe8-ohmamplifier
tap,althoughthe4-ohmorthe16-ohmtapcanbe
used without danger of damage toamplifieror loud-
speakers.
WIRE SIZESInfactory-installedJBL systems,
18-gage strandedinsulated wire is used forconnec-
tion ofcomponents.Inhomeinstallations, 18-gage
strandedor solid wire orordinarycommercial
lampcord maybe used forspeaker-amplifiercon-
nectionsupto50feet.
CONNECTING TO AMPLIFIER Fasten the
leads from youramplifiertothetwopush-type
terminal posts onthefaceofthe dividing network.
The"B"orblackpost connects totheblack,or
common, lead.The"R"orredpost connects tothe
8or16ohmamplifiertap.Nosolderingisrequired.
Simply depress thecoloredbutton,insertthe bare
endofthelead wire, and release.
CONNECTING TOSPEAKERSMostJBLnet-
works aremountedonanescutcheonplate which
fits intothestandardmountingcutoutonthe
enclosure.Leadwires from the speakers are
broughtouttothepush-typeterminal posts on
thepanelthrough eyelets intheescutcheonplate.
Properconnectionsof speakers tothevariousJBL
networksareexplainedbelow. Care shouldbetaken
to follow connectinginstructionsexactlyto ensure
thatthesystem will operate in phase: thatis,so
thata signal from theamplifier will cause both
diaphragmstomoveinthe same directionatthe
same time.

CONNECTING THELX11Emergingfromthe
chassis oftheLX11networkarefourwires:two
black,one green andonered. Connect the green
wire totheredterminal post oftheLE10Alow
frequency loudspeaker. Connect theredwireto
theredterminal post oftheLE20highfrequency
transducer. Connect theblackwirestotheblack
posts ofthe speakers. Since these twowiresare
connected intheinternalcircuitryofthe net-
work, either blackwiremaybe connected to either
speaker.
CONNECTING THELX8TheLX8networkis
connected inthe same wayastheLX11. Connect
the green wiretotheredterminal post ofthe
LE14A lowfrequency loudspeaker. Connect the
redwiretotheredterminal post oftheLE20high
frequency transducer. Connect theblackwiresto
theblack posts ofthe speakers — either wireto
either speaker.
CONNECTING THEN400,N1200,N2400andLX2.
Each of these fourdividingnetworksis connected as
showninthediagrambelow:
CONNECTING THELX5,LX13,andLX10. These
networksare connected to speakers asshowninthe
diagrambelow:
ExtendedRange
orlowfrequency
speaker
Highfrequency
transducer
network
ToAmplifier
Lowfrequency
speaker
Highfrequency
transducerand
hornorhorn/lens
Network
ToAmplifier

CONNECTING THEN7000TheN7000 divid-
ing networkprovidesa means ofaddingthe075to
existing high-quality two-way loudspeaker sys-
tems toobtainadded brilliance inthevery high
frequencies.Itisconnectedtothe high frequency
terminals ofthemain dividing networkasshown
in thediagramsbelow:
Main
Network
To
Amplifier
Lowfrequency
speaker
075
.N400, N500orN1200
Main
Network
To
Amplifier
Lowfrequency
speaker
075
LX5 orLX7
JAMESB.LANSINGSOUND,INC., 3249 CASITAS AVE.,LOS ANGELES 39, CALIF.
Highfrequency
transducerand
hornorhorn/lens
Highfrequency
transducerand
hornorhorn/lens
N7000