Page 1
JBL
DIVIDING NETWORK
INSTRUCTION MANUAL
JBL
PUBLICATION OM22-3
Page 2
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
use circuits carefully de-
signed
to
give
an
imperceptible
transition from
low
to high
frequency
transducers.
Unlike
ordinary
all-purpose
networks,
each
JBL circuit is specifi-
cally
engineered
to
match
the
characteristics
of
the JBL
transducers
with
which it is
used,
and
should
not be
connected
to
components
for which
it
is not
designed.
Components
which
match
each
of
the JBL dividing
networks
are listed in the
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
LEI 75
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
Any two-way
system
075
Continuously
variable
4 to 16
3
Page 3
SOPHISTICATED
CIRCUITRY
Dividing
networks are used in two-way
loud-
speaker
systems to electrically channel low
tones
to
the
bass
loudspeaker and
high
notes
and over-
tones
to the
high
frequency transducer.
If a dividing
network is to
fulfill
its
function
with-
out
compromise, it must be able to handle extreme
variations
in dynamics, the
full
range of audio
frequencies, complex transients, and the
varying
impedance of a loudspeaker load.
JBL
dividing
networks are
carefully
designed to
complement the exact characteristics of the JBL
transducers
with
which
they are to be used. Each
network
circuit
controls the signal to the
high
and low frequency transducers in such a way that
smooth
acoustic
response
is maintained through
the
full
audio spectrum. Thus, the effects of
indi-
vidual
speaker
characteristics, impedance
fluctua-
tions,
and the physical separation of the two sound
sources
are all taken
into
account in the complete
system design.
Naturally,
such sophisticated engineering de-
mands very close tolerances in production if all the
benefits of the design approach are to be realized.
Ordinary
networks, for example, often use electro-
lytic
capacitors
with
tolerances of plus or minus
20%.
Response
through the crossover region is
ragged, and characteristics vary
from
unit
to
unit.
All
JBL networks, on the other hand, use
only
non-
inductive
paper or mylar dielectric capacitors (not
electrolytic
units)
individually
tested to meet JBL
tolerances. The special inductors used in JBL net-
works
have extremely low insertion loss so that
none of the
driving
power to the loudspeaker
system is wasted in the network. Each inductor
is
calibrated on a sensitive electronic bridge and
its
value set precisely. To meet JBL production
tolerances, network components must check out
within
plus or minus 1% of the established design
value.
Page 4
MOUNTING IN JBL
ENCLOSURES
JBL
dividing
networks are normally installed in
the back panel of the loudspeaker enclosure. In
JBL
enclosures, they may be easily installed di-
rectly
into the mounting hole
which
is provided.
Make
sure
that the white tubular
gasket
is in place
around the network flange. Center the network
into
the mounting hole and
secure
by
driving
four
#6 x %" round
head
wood
screws
into the outside
surface of the panel. (To
install
the
LX4-2
net-
work
into the standard cutout, the F2 mounting
flange is required.)
MOUNTING IN
CUSTOM
ENCLOSURES
Dimensions for the required mounting hole are
shown in the diagram. (To mount the
LX4-2
in
a cutout of this size, the F2 mounting flange is
required.)
If
you mount the network in the
same
compart-
ment as the low frequency driver, make
sure
that
the mounting hole is cut exactly. Otherwise, the
white
tubular mounting
gasket
will
not
seal
prop-
erly,
and the resulting air leaks may introduce
objectionable
hisses
and whistles into the system.
Page 5
ADJUSTING
HIGH
FREQUENCY
GAIN
Since
the high frequency characteristics of rooms
cannot
be predicted,
each
JBL
dividing
network
is provided
with
a high frequency level control,
which
makes
it possible to
achieve
a realistic tonal
.
balance
under
a variety of room conditions. The
acoustics
of your listening room and your personal
listening
taste
will
dictate the setting which
will
provide the most pleasing performance.
The control
enables
you to adjust the power fed to
the high frequency
transducer.
It
does
not affect
the
crossover
frequency, nor
does
it
limit
the
upper
frequency
response
of the
loudspeaker
system.
Some
experimentation
with
this control is usually
necessary
when the
system
is
first
installed in its
permanent
location. If musical reproduction
seems
to be
shrill
and edgy, turn the control counterclock-
wise to a lower setting. If it
seems
dead
and
dull,
turn
clockwise to a higher setting. Comparative
listening
tests
should be
made
at the usual listen-
ing
location.
Once
the control is set for
best
overall
results, it
need
not be
changed.
You can compen-
sate
for additional differences in
source
material
with
your preamplifier controls.
THE
MODEL N500
The JBL N500
dividing
network is a professional
unit
designed
primarily for
theater
installations.
It
is usually mounted on top of the
enclosure
or
in
some
other visible and convenient location.
All
terminal
screws
lying
on the white line are
common. The output
screws
on this line should be
connected
to the black
speaker
terminals. The two
screws
marked "LF" are internally
connected
so
that connecting an LF driver to
each
set of
posts
effectively
connects
the drivers in parallel.
The gain of the high frequency unit may be
adjusted by changing the position of the strapping
bar. Zero position provides the maximum intensity
level
of the HF unit. Each
successive
step
lowers
the HF level one db.
Page 6
CONNECTING
JBL
NETWORKS
NETWORK
IMPEDANCE
All
JBL
dividing
net-
works
are matched to the characteristic impedance
of
the
transducers
with
which
they are
used.
Model
N500
is a 16-ohm network and should be connected
to
the 16-ohm amplifier tap for most efficient power
transfer. All other JBL networks
will
operate
most
efficiently
when connected to the 8-ohm amplifier
tap, although the 4-ohm or the 16-ohm tap can be
used
without
danger
of
damage
to amplifier or
loud-
speakers.
WIRE
SIZES In factory-installed JBL
systems,
18-gage
stranded insulated
wire
is
used
for connec-
tion
of components. In home installations,
18-gage
stranded or
solid
wire
or ordinary commercial
lampcord
may be
used
for speaker-amplifier con-
nections up to 50 feet.
CONNECTING
TO
AMPLIFIER
Fasten
the
leads
from
your amplifier to the two push-type
terminal
posts
on the face of the
dividing
network.
The "B" or black post
connects
to the black, or
common,
lead. The "R" or red post
connects
to the
8 or 16 ohm amplifier tap. No soldering is required.
Simply
depress
the colored button, insert the
bare
end of the lead
wire,
and
release.
CONNECTING
TO SPEAKERS Most JBL net-
works
are mounted on an escutcheon plate
which
fits
into the standard mounting cutout on the
enclosure. Lead wires
from
the
speakers
are
brought out to the push-type terminal
posts
on
the panel through
eyelets
in the escutcheon plate.
Proper connections of
speakers
to the various JBL
networks are explained below.
Care
should be taken
to
follow
connecting instructions exactly to
ensure
that the system
will
operate
in
phase:
that is, so
that a signal
from
the amplifier
will
cause
both
diaphragms to move in the
same
direction at the
same
time.
Page 7
CONNECTING
THE LX11 Emerging from the
chassis
of the LX11 network are four wires: two
black, one
green
and one red.
Connect
the
green
wire
to the red terminal
post
of the LE10A low
frequency
loudspeaker.
Connect
the red wire to
the red terminal
post
of the LE20 high frequency
transducer.
Connect
the black wires to the black
posts
of the
speakers.
Since
these
two wires are
connected
in the internal circuitry of the
net-
work,
either
black wire may be
connected
to
either
speaker.
CONNECTING
THE LX8 The LX8 network is
connected
in the
same
way as the LX11.
Connect
the
green
wire to the red terminal
post
of the
LE14A
low frequency
loudspeaker.
Connect
the
red wire to the red terminal
post
of the LE20 high
frequency
transducer.
Connect
the black wires to
the black
posts
of the
speakers — either
wire to
either
speaker.
CONNECTING
THE N400, N1200, N2400 and LX2.
Each
of
these
four dividing networks is
connected
as
shown in the diagram below:
CONNECTING
THE LX5, LX13, and LX10.
These
networks are
connected
to
speakers
as shown in the
diagram below:
Extended Range
or low frequency
speaker
High frequency
transducer
network
To Amplifier
Low frequency
speaker
High frequency
transducer and
horn or horn/lens
Network
To Amplifier
Page 8
CONNECTING
THE N7000 The N7000
divid-
ing
network provides a
means
of adding the 075 to
existing
high-quality
two-way
loudspeaker
sys-
tems
to obtain added
brilliance
in the very
high
frequencies. It is connected to the
high
frequency
terminals
of the main
dividing
network as shown
in
the diagrams below:
Main
Network
To
Amplifier
Low frequency
speaker
075
.N400,
N500 or N1200
Main
Network
To
Amplifier
Low frequency
speaker
075
LX5
or LX7
JAMES B. LANSING SOUND, INC.,
3249
CASITAS
AVE., LOS
ANGELES
39,
CALIF.
High frequency
transducer and
horn or horn/lens
High frequency
transducer and
horn or horn/lens
N7000
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