J 820M (serv.man2) - JBL Audio User Guide / Operation Manual

j 820m (serv.man2) user guide / operation manual
J 820M (serv.man2)
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User Guide / Operation Manual

Read JBL J 820M (serv.man2) User Guide / Operation Manual online

J Center
J Series OM  7/28/98 10:20 AM  Page 1
Congratulations on choosing JBL 
J Series Loudspeakers. Their highly
accurate, uncolored and balanced
sound character will greatly increase
your enjoyment of recorded music
and movies. JBL speakers are built
with careful attention to detail, using
only the highest quality materials.
They will provide many years of
excellent performance.
The J Series is the result of combin-
ing traditional JBL Signature Sound
performance values with elegant 
contemporary appearance.
Maximum Cone Surface Area:
The J Series transducers have been
designed to maximize the cone 
surface area, a technology that
allows for shorter excursion of the 
driver without sacrificing critical air
Maximum Efficiency:
Larger air
movement coupled with shorter coil
movement allows the J transducers to
be very efficient. See specifications.
Maximum Transducer Control:
Reduces distortion by tightening 
the control of driver excursion and
increasing driver linearity.
Smooth, Accurate, Extended
The J Series transducers,
computer-optimized dividing net-
works, and bass reflex cabinets com-
bine to give clear, crisp, accurate,
JBL Signature Sound.
Bookshelf Models:
For the best
stereo reproduction, the two loud-
speaker systems should be an equal
distance from your listening position
and separated so that the angle
between them, at the listening posi-
tion, is between 40 and 60 degrees
(see Fig. 1). For example, if your lis-
tening position is 8 to 12 feet (2.5m
to 4m) from each speaker, the two
systems should be about 8 feet
(2.5m) apart. Placing the loudspeak-
ers in corners or against a wall will
result in the strongest (not necessa-
rily the most accurate) bass. Except
for the J50, all J Series speakers
have their ports in the front so you
can place the rear of the speaker up
against a wall. In the case of the J50,
do not place the speaker closer than
3 inches (75mm) to the wall behind it
if possible.
For the best stereo imaging, we rec-
ommend that the systems be placed
so that the high frequency transduc-
ers are positioned approximately at
ear level of a seated listener. Every
room is different and there are differ-
ent tastes, so don’t hesitate to experi-
ment on your own.
Tower Models:
The Tower models
cabinet height and driver placement
allow for speaker placement directly
on the floor. For the best stereo
reproduction, the two loudspeaker
systems should be an equal distance
from your listening position and sepa-
rated so that the angle between
Fig. 1
J Series OM  7/28/98 10:20 AM  Page 2
them, at the listening position, is
between 40 and 60 degrees. For
example, if your listening position is 
8 to 12 feet (2.5m to 4m) from each
speaker, the two systems should be
about 8 feet (2.5m) apart. 
Center Channel Model:
As the 
center channel contains the dialog
and other central action sounds, the
speaker should be located very close
to the Monitor/TV and centered with
the Monitor/TV’s center line.  Place
the J Center directly on top of or
directly below the Monitor/TV with the
front edge of the speaker grille flush
with the edge of the Monitor/TV.  You
should have your Left and Right
speakers within a 2 ft or less height
range of your Center Channel for
proper sonic performance (see Fig. 2).
In Case Color Interference Occurs:
The speaker is shielded to work with
video applications, however some
color interference may be observed
on the TV screen depending on the
type of your TV set.  If color interfer-
ence is observed, turn your TV off for
15 minutes and move the speaker
back about 1" from the front edge of
the TV.  Turn on TV and recheck.  If
this is not far enough, move back fur-
ther and experiment until the interfer-
ence disappears.  You may have to
turn the TV off for a few minutes and
turn it on again to clear the screen.
To connect the loudspeaker systems
to the receiver or amplifier, use two-
conductor insulated wire. Your JBL
dealer can recommend suitable
cables, or you can buy wire at most
hardware or electronic stores. We
recommend #16 AWG wire as a mini-
mum size. If your speaker is more
than 30 feet (10m) from your receiver
or amplifier, use larger diameter
lower gauge wire. Connections are
made at the terminals located on the
back of the J Series speakers.
Preparing the Hookup Wire
Carefully plan your wire lengths
before cutting any speaker wire.
Be sure to allow plenty of extra
wire to help hide paths in corners,
along baseboards, etc.
1. For Left and Right Speakers, first
determine the wire length needed
between the most distant speaker
and the receiver or amplifier. 
2.  Now make the hookup wires for
both speakers this length, even if one
loudspeaker is much closer to your
amplifier than the other.  This will
help maintain proper signal balance.
(For the J Center, determine the
length needed from AV receiver’s
center channel output to speaker).
3. Strip off 
" of insulation from both
ends of each conductor.
4.  Twist each set of thin wires into a
tightly-bunched spiral.
5.  At this point you need to identify a
visual difference between the two
conductors of each molded pair of
speaker wire. Differentiating marks
can be a different color wire (copper
or “silver”); a strand of yarn in one
conductor; thin, raised ribs on one
(2 ft. or less)
(2 ft. or less)
Fig. 2
J Series OM  7/28/98 10:20 AM  Page 3
part of the outer insulation; or a 
printed “+” marking on one of the
insulators. It does not make any 
difference which of the two strands of
wire go to (+) and (–) on the speakers
and amplifier, as long as all speakers
used in your system are connected
identically. Push down on the button
below the terminal and insert the wire
through the hole.
For each channel, the red terminal on
all loudspeakers should be connected
to the red or (+) speaker connection
terminal on the receiver or amplifier,
and the black to black or (–) speaker
connection terminal (see Fig. 3).
Connecting the loudspeakers in this
manner ensures that they will be in
phase; that is, work together rather
than in opposition.  This is very
important when connecting sev-
eral speakers together in a Dolby
Pro-Logic AV application. Connecting
the loudspeakers out of phase will
not damage them, but will result in
less bass and poor imaging.
When connecting the J Center or
other J Series speakers to a Dolby
Pro-Logic AV receiver, refer to the
instructions accompanying your AV
component for use of the “test tone”
to properly balance the sound output
from each speaker. The use of the
“test tone” and the controls on your
AV receiver will enable you to cor-
rectly balance the level (volume) of
sound coming from each speaker in
your Dolby Pro-Logic application.
Hooking Up Multiple Sets 
of Speakers
If your receiver has two complete
sets of speaker terminals (“A” and
“B”), it’s possible to hook up an addi-
tional pair of speakers for 
sound in another room. However,
some speakers may not be usable as
a second pair if you want to play two
sets at once. Before hooking up
another set of speakers besides your
J Series loudspeakers, check the 
Your amplifier’s 
minimum load
nominal impedance 
of the
second set of speakers. Both of
these specifications are expressed in
ohms and both can be found in the
owner’s manuals which came with
your speakers and amp/receiver. The
receiver’s minimum load impedance
is determined by whether or not
power ratings are given for 4 ohms.
This is because two sets of 8 ohm
speakers will present a 4 ohm load to
the receiver. The J speaker, when
combined with an 8 ohm speaker,
produces an impedance sufficiently
close to 4 ohms.  For example, the
following entry in an amplifier owner’s
manual. . .
A)100 watts RMS into 8 ohms, both chan-
nels driven, 20-20kHz with less than
B) 160 watts RMS into 4 ohms, both
channels driven, 20-20kHz with less than
0.02% THD.
Red Blk.
(+) (–)
Fig. 3
J Series OM  7/28/98 10:20 AM  Page 4
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Download JBL J 820M (serv.man2) User Guide / Operation Manual

Here you can read online and download JBL J 820M (serv.man2) User Guide / Operation Manual in PDF. J 820M (serv.man2) user guide / operation manual will guide through the process and help you recover, restore, fix, disassemble and repair JBL J 820M (serv.man2) Audio. Information contained in service manuals typically includes schematics / circuit diagrams, wiring diagrams, block diagrams, printed wiring boards, exploded views, parts list, disassembly / assembly, pcb.