JBL GT1200 User Manual
Page 2
01
installation methods for your par-
ticular vehicle. If you do not feel
you have experience, do not
attempt the installation yourself,
but instead ask your authorized
JBL dealer about professional
installation options.
Remember to keep your sales
receipt with this manual in a safe
place so both are available for
future reference.
Thank you
for choosing a
JBL GT Series subwoofer. GT
Series subwoofers are designed
to suit a broad range of mobile
audio applications and can be
used in a wide variety of enclo-
sure types to produce extended,
powerful bass in a limited
amount of vehicle space. To
ensure maximum subwoofer
performance, we strongly rec-
ommend that installation be left
to a qualified professional.
Although these instructions
explain how to install a GT
Series subwoofer in a general
sense, they do not show box con-
struction details and exact
Enclosure Calculations
and Building Boxes
Use the recommended box
designs on the enclosed data
sheet or look for them on our
Web site at www.jbl.com. Choose
cabinet dimensions to fit your
vehicle, but do not change the
enclosure’s volume. Doing so will
change the tuning frequency of
the enclosure and may adversely
affect final performance. If you
cannot perform the necessary
calculations yourself, please con-
tact your authorized JBL dealer
for help and information about
JBL Speakershop™, a dedicated
enclosure-design software pro-
gram for experienced car-audio
enthusiasts.
Your Car and Bass
Reproduction
Depending on the size of the vehi-
cle’s interior listening space,
reproduced bass frequencies
below 80Hz are actually boosted
by nearly 12dB per octave as fre-
quency decreases. NOTE: This
effect, known as the vehicle’s
transfer function, plays an impor-
tant part in shaping the overall
in-car response and is displayed
graphically along with freespace
response on the enclosed data
sheet for your GT Subwoofer.
GTSubwoofers Owner's Manual 7/14/98 2:19 PM Page 2