JBL
DIVIDING NETWORK
INSTRUCTION MANUAL
JBL
PUBLICATION OM22-3
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
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
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.
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