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Introduction / Installation JBL BASSTUBE BTX250
Thank you for choosing the JBL
BTX250. BTX250 has been designed
to provide the kind of high-perfor-
mance low-frequency reproduction that
used to require big, clumsy enclosures,
large amplifiers, and complex installa-
tion. To ensure maximum performance,
we strongly recommend that installa-
tion be entrusted to a qualified profes-
sional. Although these instructions
explain how to install the BTX250 in a
general sense, they do not show the
specific installation methods for your
particular vehicle. If you feel you do not
have the necessary tools or experience,
do not attempt the installation yourself;
rather, ask your authorized JBL car
audio dealer about professional instal-
lation options.
Remember to keep this manual and
your sales receipt in a safe place for
future reference.
Instructions BTX250
Hearing WARNING!
Playing loud music in a vehicle can
permanently damage your hearing, as
well as hinder your ability to hear traf-
fic. We recommend using low volume
levels while driving. JBL accepts no lia-
bility for hearing loss, bodily injury or
property damage resulting from the
use or misuse of this product.
Your car and bass reproduction
Depending on the interior volume of
your vehicle and the dimensions of the
passenger compartment and cargo
area, reproduced frequencies below
80Hz may be boosted by nearly 12dB
per octave as frequency decreases.
This effect, known as the vehicle’s
“transfer function” or “cabin gain,” plays
an important part in shaping the overall
in-car response of the BTX250.
BTX250 is designed to reproduce fre-
quencies below about 100Hz, but
there may be other speakers in your
vehicle that reproduce some of those
same frequencies. It is important that
all the speakers work together to
reproduce frequencies they share.
Depending on the orientation of the
BTX250 and the distance from it to the
other speakers, the BTX250 and the
other speakers may be "in-phase" or
"out-of-phase". The resulting condi-
tions, known as constructive and
destructive interference, also play a
role in shaping the frequency response
of your system.
Fortunately, BTX250 has controls to
optimize both of these conditions and
their adjustment is explained later in
the manual.
INSTALLATION
CHOOSING A MOUNTING
LOCATION
Choose a location that doesn’t interfere
with the loading or unloading of cargo,
fold-down rear seats, or opening or
closing of the trunk lid. The best loca-
tion is likely to be the front or rear cor-
ner of the trunk or luggage compart-
ment.
These locations, in addition to being
out of the way, will provide the best
sonic reproduction in the 60Hz to
100Hz range because the woofer out-
put will be “corner loaded” against the
vehicle’s walls. In any case, BTX250
must not interfere with the safe opera-
tion of the vehicle.
Once you’ve chosen a mounting loca-
tion and made the necessary electrical
connections, you’re ready to mount
BTX250 securely to the mounting sur-
face (most likely the floor of the lug-
gage compartment).
Caution: Make sure mounting screws
will not puncture wiring harnesses,
brake or fuel lines, or the vehicle’s fuel
tank. Some or all of these may be
located behind or under the mounting
surface.
Horizontal Mounting: Lock the fixing
holders supplied (x2) on the metal bar
of the BTX250 on each side. Then find
the right place where the BTX250 will
be installed and mark the exact posi-
tion where the fixing holders will be
located (figure 1). Then remove the fix-
ing holders from BTX250. Screw the
fixing holders on the position marked
initially (figure 2). Put back in place the
BTX250 in the fixing holders and press
the lock to fasten the metal bar in posi-
tion (figure 3).
Figure 1
Figure 2
Figure 3