JBL 250Ti Jubilee User manual

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250Ti Jubilee Instruction Manual
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Contents
The 250Ti Jubilee............................................................. 2
Placement......................................................................... 2
Speaker Wire.................................................................... 3
Connections ..................................................................... 3
Amplifier Power Recommendations................................ 5
Biased Crossover Battery Replacement........................... 6
Grille ................................................................................. 6
General Care..................................................................... 7
Service.............................................................................. 7
Specifications................................................................... 7
The 250Ti Jubilee
A definitive expression of quality and craftsmanship, the
250Ti Jubilee is the most advanced JBL loudspeaker built
for the home. No effort has been spared and no perfor-
mance factor has been overlooked in building the most
accurate loudspeaker possible, from the singular shape
of the enclosure to the design of the level controls. The
woodworking of the 250Ti Jubilee – with each hand-
detailed enclosure carefully crafted of dense fiberboard
and finished in high-gloss lacquer – complements the
engineering.
The 250Ti Jubilee will sound as good as your equip-
ment and program source will allow. Imaging is precise
and stable. Frequency response, both on and off axis, is
nearly ruler-flat to well beyond the audible bandwidth.
Distortion is held to levels more typical of fine electronics
than of loudspeakers.
Despite its sophistication, the 250Ti Jubilee is easy to
set up properly. Please read this manual thoroughly before
beginning. The instructions and information it contains will
ensure a trouble-free setup and will allow you to realize the
full potential of your system.
Placement
For the best performance, place your 250Ti Jubilee speakers
at least three feet from any walls, and equidistant from your
primary listening position (there is no designated right or
left speaker). The location of your primary listening position
is determined by the distance between the speakers; the
area created between the loudspeakers and the listening
position should ideally equal a 40- to 60-degree angle. For
example, if the loudspeakers are 2.4m (8 feet) apart, your
listening position should be 2.4 – 3.65m (8 to 12 feet) from
each speaker. To widen the area in which the best stereo
image will be perceived, turn the speaker to face the primary
listening position.
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Speaker Wire
Speaker wire and interconnecting cables are an important
component in an audio system. The 250Ti Jubilee system
is internally wired with specially designed cable manufac-
tured for JBL by Monster Cable®. The same care that was
taken in selecting internal system wiring should be taken
in selecting and applying the cables that will connect the
various system components. Your 250Ti Jubilee dealer
has the experience and knowledge to recommend suitable
interconnects and speaker wire to best complement your
system.
The following gauge wires (minimum requirements) are
recommended:
Gauge Distance
1 mm2 (18 AWG) Up to 5 meters (15 feet)
1.5 mm2 (16 AWG) Up to 10 meters (30 feet)
2 mm2(14 AWG) Up to 25 meters (75 feet)
The length of the wire will depend on the location of the
loudspeakers and amplifier. Since you should listen care-
fully to your loudspeakers
before determining their final
position, you may want to arrange a temporary wiring
layout that allows you to move the loudspeakers and
experiment with their placement. After you have deter-
mined the best location for the system, permanent con-
nections may then be made using the shortest cable runs
possible. Use the same length wires for both speakers.
In some systems, the amplifier may be located near
the loudspeaker system and connected using a short
length of wire. Although such a hookup requires a
relatively long cable between the preamplifier and main
amplifier, the benefit of the short amplifier-to-loudspeaker
connection often outweighs any drawbacks.
Connections
WARNING: Be sure your amplifier is turned off before
connecting or disconnecting the loudspeakers. Making con-
nections while the amplifier is operating could seriously
damage the loudspeaker system and void the warranty. The
amplifier must also be turned off before connecting or dis-
connecting cables at the amplifier or preamplifier inputs.
Before you begin. Examine your speaker wire carefully.
One conductor is solid, and the other is differentiated
by a ridge, printed marking or color stripe. Assign one
conductor positive (+) and the other negative (–) polarity,
and always connect the designated conductors to their
respective amplifier and loudspeaker terminals, positive-
to-positive, and negative-to-negative. This will ensure that
the loudspeakers will work together (in phase) rather than
in opposition. (Connecting the loudspeakers out of phase
will not cause damage but will result in reduced low-
frequency output and lack of stereo effect.)
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JBL 250Ti Jubilee loudspeakers are designated to pro-
duce a positive pulse when a positive voltage is applied to
the positive (red) terminal. Some audio amplifiers invert
polarity (i.e., reverse the polarity of both channels). Before
you make your final connections, audition the system
carefully with both normal (+ amp to + speaker) as well as
reversed (+ amp to – speaker) connections to determine
the best method. The “correct” connection is the one that
yields the best audible results. Be sure to reverse both left
and right connections to keep the system in phase.
Connections to the 250Ti Jubilee loudspeaker system
are made at the two terminals located on the back of the
enclosure, which are designed to permit a variety of con-
nection methods, as described below. Each method has
its own advantages. Experimentation, and the advice of
your JBL 250Ti Jubilee dealer, will be helpful in choosing
the best method for your system.
Bare Wire Method
The most positive connection is made by directly connect-
ing clean, bare wire. For each terminal, separate each wire
into three equal bundles.
Turn the terminal counterclockwise and pass the cen-
ter bundle through the exposed hole in the binding post.
Wrap the remaining bundles around the post and twist
them together with the center strands. Tighten the knob
securely so that a snug, positive connection over a maxi-
mum area is achieved. Do not apply excessive force, and
do not overtighten . Trim off any excess wire that is not in
contact with the binding post contact surfaces to avoid a
short circuit.
Spade or Banana-type Connector Method
This method involves fastening the ends of wires to spade
or banana-type connectors which are then, in turn,
attached to the binding posts. Bear in mind, however, that
there is an advantage to keeping the number of contacts
to a minimum. If this type of connection is desired, we
recommend using the highest-quality terminals, expertly
connected to the selected cables.
“Bi-Wire” Connecting Method
The system’s internal dividing network is electrically sepa-
rated at the low-frequency to midrange transition. External
strapping bars connect the networks when a single-wire
connection method is used (the system is shipped from
the factory with the strapping bars in place). By removing
the bars, connections may be made to the individual net-
work sections using two wires (four conductors). The
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same type of wires may be used for both low-frequency
and high-frequency sections to reduce wire effects (resis-
tance, inductance, etc.) and to avoid intermodulation of
low and high frequencies.
In some systems, using specialized wires for low-fre-
quency and high-frequency sections may yield excellent
results. In either case, low-frequency cables should be as
short as possible, and the left and right cables for each
section must be the same length. CAUTION: Never con-
nect two amplifier channels to the same loudspeaker
without first removing the strapping bars. Operating two
amplifier channels with the bars in place will seriously
damage the amplifiers and void the warranty.
The bi-wire option also enables you to power the
system with two amplifiers. Four identical amplifiers (or
two dual-channel units) may be used, although specialized
low- and high-frequency amplifiers offer clear advantages.
Your JBL 250Ti Jubilee dealer can recommend the amplifi-
cation that will best suit your needs. In all cases, the left
and right amplifiers for each section must be identical.
Make sure that the input sensitivity of the two amplifiers is
equal, or that input level controls are provided to maintain
the proper low-to-mid/high balance. If you are using two
identical stereo amplifiers, you may locate one near each
loudspeaker and drive low- and high-frequency sections
through short wire runs.
Input polarity must be the same for both low- and
high-frequency sections. Some amplifiers invert polarity.
If the polarity is reversed to one section, a discontinuity
in response will be apparent in the crossover region.
If a problem is suspected, reverse the polarity to either
low- or high-frequency sections of both loudspeakers.
Amplifier polarity markings may not ensure correct
polarity connections.
Maintaining Connections
All connections should be inspected and cleaned or
remade periodically. Frequency of maintenance depends
on the metals involved in the connection, atmospheric
conditions and other factors. Consult your dealer for
specific recommendations.
Amplifier Power Recommendations
The 250Ti Jubilee is capable of handling 200 watts contin-
uous (based on an 8-hour test using broadband noise
shaped to simulate the power distribution of music) with
peaks of up to 800 watts (indicating the system’s ability to
handle transient peaks well above average power levels).
Unfortunately, amplifier power ratings generally refer only
to continuous, steady-state power levels measured with a
test signal, and are only an
indication of how loud the
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system will play without distortion. More important than
the power rating is the quality of
sound the amplifier is
capable of, or its
dynamic power capability . Since am-
plifier specifications are not a reliable indicator of sound
quality, an amplifier should be chosen only after careful
listening. If it can achieve the desired volume level without
distortion, then the amplifier has sufficient power, regard-
less of its rating. Your JBL 250Ti Jubilee dealer can make
recommendations and arrange auditions to help you select
suitable amplification for your system.
NOTE: If four amplifier channels are used, the high-fre-
quency amplifier may be up to 6dB less powerful than the
low-frequency amplifier. This is because the low-frequency
section requires approximately four times the power of the
high-frequency section, due to the power versus frequen-
cy distribution of music. For example, if a 200-watt low-
frequency amplifier is used, a 50-watt high-frequency
amplifier will clip, or “run out of power” at approximately
the same level, when playing music.
Do not use fuses or circuit breakers of any kind
between the amplifier and loudspeakers. Such devices will
seriously degrade the sound quality and do not ensure
protection from loudspeaker damage. The key to safe
operation is having adequate amplifier power to avoid dis-
tortion at the highest sound levels required.
Biased Crossover Battery Replacement
The crossover network in the 250Ti Jubilee uses a 9V
battery to maintain a charge on the capacitors used in the
midrange, high-frequency and ultrahigh-frequency circuits.
The purpose of this charge is to allow the capacitors to
operate in a “class A” mode. This treatment gives the sys-
tem greater detail and spatial properties than a traditional
network. The current drain on the battery is extremely
small. The average battery life is 3 to 4 years. When
replacement is required, remove the two top center
screws on the network cup and carefully lift off the curved
battery cover. The battery is held in a clip on the left side
of the network. Simply remove the old battery and replace
it with a new one. Reinstall the cover and screws.
BATTERY
BI-AMP
High Frequency
Low Frequency
JBL, INCORPORATED
8500 Balboa Blvd., Northridge, CA USA
NORMAL/
BI-WIRE
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Grille
Loudspeaker grilles protect the transducers and enhance
the appearance of the system in many rooms. However,
even the most acoustically transparent grille affects the
sound. On the 250Ti Jubilee, the effect is minor, particular-
ly for casual listening or background music, but apparent.
For serious listening in circumstances where damage is
unlikely (i.e., when small children are not present), we
recommend that the grille be removed.
General Care
The 250Ti Jubilee is finished in high-gloss lacquer. The
beautiful, deep-gloss finish is the result of a meticulous
multistep painting and polishing procedure. Treat the sur-
face very carefully to avoid scratching the finish. Use only
lint-free cotton cloths for dusting. To remove fingerprints
and smudges, an ammonia-free window cleaner may be
used; apply a small amount to a lint-free cotton cloth and
gently clean the surface. Never use any abrasive cleaners
or strong chemicals to clean the enclosure. In case of
deep scratches or damage, please consult a qualified
furniture repair shop.
The grille may be gently vacuumed in the removed
position only. Stains may be removed with an aerosol
cleaner, following its instructions. Do not use solvents on
the grille.
Service
JBL 250Ti Jubilee loudspeakers are designed to provide
years of trouble-free service. No maintenance is required.
If a problem is suspected, first make sure that all connec-
tions are properly made and clean. If a problem exists in
one loudspeaker, reverse the speaker wires to the left and
right system. If the problem remains in the same system,
then the fault is in the loudspeaker. If the problem appears
in the opposite system, the cause is in another component
or cable.
Do not move loudspeaker cones or diaphragms by
hand. The voice coil assembly is aligned with extreme
precision and the clearance is very small. Any attempt to
move the assembly by hand can easily force the coil out of
alignment and cause distortion or failure.
Should your 250Ti Jubilee system ever need service,
contact the JBL dealer or distributor from whom it was
purchased. If this is not possible, write directly to the JBL
Customer Service Department, describing the problem as
fully as possible, and wait for return authorization. Do not
return products to the JBL factory without prior authoriza-
tion. Address correspondence to: JBL Customer Service,
80 Crossways Park West, Woodbury, NY 11797
Telephone: [phone], or [phone]. Outside
the United States, contact your local JBL distributor.
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Specifications
250Ti Jubilee
Low Frequency: 360mm (14 in.)
Midrange: 200mm (8 in.)
130mm (5 in.)
High Frequency: 25mm (1 in.)
Titanium Dome
Frequency Response: ±2dB, 50Hz – 21kHz
Usable Response (– 6dB): 30Hz – 25kHz
Sensitivity: 89dB, 2.83 volts @ 1m
Power-Handling Capability: 200 watts continuous
800 watts peak
Nominal Impedance: 8 ohms
Crossover Frequency: 350Hz, 1.2kHz, 5kHz
JBL continually engages in research related to product
improvement. New materials, production methods and
design refinements are introduced into existing products
without notice as a routine expression of that philosophy.
For this reason, any current JBL product may differ in
some respect from its published description, but is always
warranted to equal or exceed the original design specifica-
tions unless otherwise stated.
JBL Consumer Products
80 Crossways Park West, Woodbury, NY 11797
8500 Balboa Boulevard, Northridge, CA 91329
www.jbl.com
©1997 JBL, Incorporated. JBL is a registered trademark of JBL, Incorporated.
Printed in USA 10/97 Part No. 250TIJUBOM
A Harman International Company
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