SC305
CENTER CHANNEL
SPEAKER
OWNER’S
MANUAL
INTRODUCTION
Congratulations on choosing JBL
Series loudspeakers. Their highly
accurate, uncolored and balanced
sound character will greatly increase
your enjoyment of recorded music.
JBL speakers are built with careful
attention to detail, using only the
highest quality materials. They will
provide many years of excellent performance.
The SC305 Center Channel Speaker
is the result of concentrated efforts to
combine traditional JBL performance
values with elegant contemporary
appearance. Some of the engineering features of the SC305 are:
Smooth, extended response:
The 14mm Titanium Laminate dome
tweeter, dual 5" polymer laminated
cone drivers and carefully designed
dividing network deliver the clear,
crisp, quality sound reproduction
needed to deliver the accurate, intelligible vocal information required by a
center channel speaker.
305
SC
High Quality Crossover
Network: the computer-optimized
dividing network employs up to thirdorder (18 dB per octave) crossover
sections. JBL's use of high quality
capacitors and low-loss/low-distortion
inductors assures freedom from
phase or amplitude distortions.
Magnetic Shielding: prevents stray
Fig.2
Fig.1
magnetic fields from creating any
interference or distortion of the video
picture. This allows placement of the
SC305 directly on top of, or directly
below the video monitor.
Cabinet Design: the multi-angled
cabinet provides options of locating
the SC305 directly on top of the video
monitor or on the floor in front of the
monitor.
PLACEMENT
As the center channel contains the
dialog and other central action
sounds, the speaker should be located very close to the video monitor
centered with the monitor's center line.
The SC305 can be placed in two locations:
1) On top of the video monitor.
Place the large flat bottom of the
speaker directly on top of the monitor,
with the front edge of the speaker
grille flush with the edge of the monitor. The speaker grille/baffle should
be pointing directly at the listener.
See Fig. 1.
2) On the floor directly in front of the
monitor.
cabinet on the floor so that the speaker grille/baffle is pointing directly
at the listener. The grille can be
removed and re-installed so the JBL
Logo is oriented properly. See Fig. 2.
Place the angled side of the
CENTER LINE
CONNECTIONS
To connect the SC305 to the center
channel output of your AV receiver or
amplifier, use two-conductor insulated
wire. Your JBL dealer can recommend
suitable cables, or you can buy wire at
most hardware stores. We recommend #16 AWG wire as a minimum
size. If your speaker is more than 30
feet (10 m) from your AV receiver or
amplifier, use larger diameter wire.
Connections are made at the terminals located on the back of the SC305
speaker. The terminals accept bare
wire or dual banana plugs, either of
which will provide easy, secure connections.
CENTER
LINE
Preparing the hookup wire
1. First determine the distance
between the most distant speaker.
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.
3. Strip off 3/8" of insulation from both
ends of each conductor.
2
4. Twist each set of thin wires into a
AV Receiver
Center
•
•
(-) (+)
Center
Speaker
Blk Red
(-) (+)
•
•
Fig. 3
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 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
both speakers are connected identically. Push down on the button below
the terminal and insert the wire, or the
banana plug, through the hole (see
Fig. 3).
POWER HANDLING
Thanks to its high efficiency, the JBL
SC305 loudspeaker will produce reasonable volume levels in a room of moderate
size with very little amplifier power.
However, using a small amplifier to obtain
the desired volume listening levels may
lead to overdriving the amplifier. This will
generate high distortion levels and may
cause damage to your loudspeaker. For
the best performance, an amplifier should
be selected with an output rating that is
greater than the maximum power that will
be used. This margin of reserve power will
ensure that the amplifier will not attempt to
deliver more power than its design allows.
However, the amplifier's power rating per
channel must not exceed the maximum
recommended amplifier power for that specific loudspeaker model. Please see the
specification section for details. Following
these guidelines will provide virtually distortion-free sound reproduction and long loudspeaker life.
TROUBLESHOOTING
The vast majority of new speaker "malfunctions" end up being traced to connections
or switch settings. Check the following tips
first, before requesting service.
The red terminal on the loudspeaker
should be connected to the red or (+)
center channel connection terminal on
the AV receiver or amplifier, and the
black to the black or (-). Connecting
the loudspeaker in this manner
ensures that it will be in phase; that is,
work together rather than in opposition
to the left and right channel speakers.
Connecting loudspeakers out of phase
will not damage them, but will result in
less bass and poor imaging.
Using the controls on your center
channel AV receiver/amp, adjust the
center channel level (volume) control
so that the sound from the center
speaker is the same level
mal listening position
at your nor-
, as the sound
from the left and right front speakers.
No sound at all or very faint sound from
the center channel speaker
1. Speaker wire has become disconnected.
2. One of the connections between sound
source and AV receiver/amp is faulty or
has become disconnected.
3. AV receiver/amp center channel mode
not selected. Please select a mode that
activates the center channel.
4. AV receiver/amp "audio direct" switch is
activated. This switch should be off to activate the 5 speaker surround mode.
5. Sound source (VDP, VCR,CD,cassette
deck, turntable) not turned on, not activated, not hooked up or not selected on AV
receiver/amp front panel.
Speaker plays at low volumes but shuts
off as volume is increased OR sound
turns on and off intermittently
A few strands of speaker wire may be
shorting out. Recheck the connections.
Recheck the impedance of the amp.
3
GENERAL CARE
The grille is held in place by pins near the
edges. To remove the grille, grasp it by
both top and bottom edges and pull gently.
To replace grille, re-position it carefully and
press gently at the corners. Do not push on
the center area of the grille.
The loudspeaker cabinet may be cleaned
with a slightly damp cloth. To remove dust
from the grille cloth, use a vacuum with a
brush attachment. Spots may be removed
with a commercial spot remover. Do not
use any cleaners or solvents on the
speaker drivers themselves.
SERVICE
Should your loudspeaker ever need service, return it to the JBL dealer from whom
it was purchased. If for some reason this is
impractical, in the United States, call 800336-4JBL for your nearest warranty station.
Military personnel who purchased from
authorized military outlets should return
them to a similar outlet or contact:
ALA Associates Enterprises
985 Ponce de Leon Avenue
Atlanta, GA 30306
Phone: 800-875-4252
FAX: 404-873-3592
If purchased outside the United States,
contact your local distributor to make
arrangements for repair service. Do not
return products to the JBL factory without prior authorization.
Specifications SC305
High Frequency Dome Transducer 14mm Titanium Laminate
Low Frequency (High Polymer Laminate) 5"(2)
Crossover Frequency 2.7 kHz
Frequency Response (- 6 dB) 100 Hz to20 kHz
Sensitivity(1 Watt/1 meter) 87 dB
Nominal Impedance 8 ohms
Recommended Amplifier Power* 10 to 100 Watts
External Dimensions (HxWxD) 7"x 20"x 6-1/2"
External Dimensions (millimeters) 178x508x165
Weight (each) 15 lbs (6.8 kg)
Shipping Weight 18 lbs (8.2 kg)
*Undistorted continuous power per channel.
JBL continually strives to improve its products. New materials, production methods and
design refinements are introduced into existing models without notice as a routine expression of our design philosophy. For this reason, JBL loudspeakers may differ in some
respect from their published specifications and descriptions, but will always equal or
exceed the original specifications unless otherwise stated.
JBL Consumer Products, Inc.
240 Crossways Park West
Woodbury, NY 11797
8500 Balboa Blvd.
Northridge, CA 91329
800 336 4JBL
Part No. 75993
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