JBL GT1000d, GT800, GT1500d, GT800d, GT1200 User Manual

®

GRAND TOURING

SERIES

Automotive Subwoofers

GT800, GT800d, GT1000, GT1000d, GT1200, GT1200d, GT1500, GT1500d Owner’s Manual

GENUINE JBL

01

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 enclo­sure types to produce extended,
powerful bass in a limited
amount of vehicle space. To
ensure maximum subwoofer
performance, we strongly rec­ommend 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 con­struction details and exact

installation methods for your par­ticular 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.

Your Car and Bass
Reproduction

Depending on the size of the vehi­cle’s interior listening space,
reproduced bass frequencies
below 80Hz are actually boosted
by nearly 12dB per octave as fre­quency decreases. NOTE: This
effect, known as the vehicle’s
transfer function, plays an impor­tant 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.

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 con­tact your authorized JBL dealer
for help and information about
JBL Speakershop™, a dedicated
enclosure-design software pro­gram for experienced car-audio
enthusiasts.

Specifications

GT Speakers

Specifications: GT800 GT800d GT1000 GT1000d

Configuration 8" woofer 8" woofer, 10" woofer 10" woofer,

Recommended power amplifier range 18W – 200W 18W – 200W 18W – 260W 18W – 260W

Sensitivity (@ 2.83 volt/1 meter) 93dB 93dB 94dB 94dB

Frequency response 35Hz – 5kHz 35Hz – 5kHz 30Hz – 3.5kHz 30Hz – 3.5kHz

Mounting Depth

Top mount 3-13/16" (97mm) 3-13/16" (97mm) 5-1/8" (131mm) 5-1/8" (131mm)
Bottom mount 4-5/16" (110mm) 4-5/16" (110mm) 5-5/8" (143mm) 5-5/8" (143mm)

Dimensions

Cut-out diameter 7-1/8" (181mm) 7-1/8" (181mm) 9-1/4" (235mm) 9-1/4" (235mm)

Specifications: GT1200 GT1200d GT1500 GT1500d

Configuration 12" woofer 12" woofer, 15" woofer 15" woofer,

Recommended power amplifier range 18W – 280W 18W – 280W 18W – 300W 18W – 300W

Sensitivity (@ 2.83 volt/1 meter) 95dB 95dB 97dB 97dB

Frequency response 25Hz – 3kHz 25Hz – 3kHz 20Hz – 2kHz 20Hz – 2kHz

Mounting Depth

Top mount 3-3/8" (86mm) 5-3/4" (147mm) 5-3/4" (147mm) 6-11/16" (170mm) 6-11/16" (170mm)
Bottom mount 6-1/4" (159mm) 6-1/4" (159mm) 7-3/16" (183mm) 7-3/16" (183mm)

Dimensions

Cut-out diameter 11-1/8" (283mm) 11-1/8" (283mm) 13-15/16" (355mm) 13-15/16" (355mm)

dual voice coil dual voice coil

dual voice coil dual voice coil

01

01

Sealed enclosures exert the most
control over the motion of a sub­woofer because the air acts like
a spring against the motion of
the woofer cone. Larger boxes
allow for more excursion (cone
movement), thus more low­frequency output for the amount
of power used. When placed in a
sealed box larger than the com­pliance (Vas) of the subwoofer, it
will perform as if it were in an
infinite baffle installation.

Vented and bandpass enclosures
have the lowest amount of excur­sion for the amount of sound out­put. This is a result of port tuning
reinforcing the sound output.
Vented boxes will not provide

adequate woofer control when dri­ven below the port tuning range,
so proper design is important. A
fourth-order bandpass box will
have the lowest overall cone
excursion at the expense of limited
bandwidth.

In addition, there are a number of
points you’ll want to keep in mind
as you construct an enclosure:

1. Use 3/4" (19mm) MDF (medium­density fiberboard) or marine
birch plywood to build an enclosure.
Enclosures for 12" and larger
subwoofers, or small subwoofers
driven by high-power amplifiers,
should be constructed using 1"
(25mm) material.

2. Seal all joints with glue and
screws; do not use nails. We
recommend “deck” or “zip” screws
since they have coarse threads
for better grip and don’t require
pre-drilling holes. Once the box
has been tested, seal all interior
joints with silicone caulk.

3. Depending on the application,

fill the enclosure according to the

design you have chosen from the

enclosed data sheet in one of three

ways: zero-percent fill (i.e., no

fill), or 50-percent fill (i.e., 1"-

thick polyfill sheets on all inside

walls except where subwoofer is

mounted), or 100-percent fill

(i.e., entire box is stuffed with

loosely-packed polyester fiberfill).

4. Use PVC or ABS pipe for ports.
Keep in mind that the openings at
either end of the port must be at
least one port diameter away
from any obstructions, including
filling material inside or outside
the box. Rectangular vents can
be used as long as the cross­section area matches the
recommended port-area values
in the enclosed data sheet.

Power-Handling
Limitations

The power-handling capability of

any woofer is related to both its

ability to dissipate heat and the

maximum excursion limits of its

cone. Once the speaker’s voice

coil moves outside the magnetic

gap, power can no longer be con-

verted into motion, and all the

amplifier’s power is converted

into heat in the voice coil. This

voice-coil heating is the largest

detriment to speaker longevity,

so overexcursion (driving the

speaker past Xmax) should be

avoided. Since speaker-cone

excursion is different for each

type of enclosure, power handling

is different for each enclosure.

• Voice-coil overheating and burn­ing due to over-excursion is often
caused by overdriving an ampli­fier into “clipping.” A severely
clipped signal, or squarewave,
contains nearly twice the power
of a clean sine wave at the same
level. Bass that sounds broken up
and distorted at higher volumes
usually indicates that the ampli­fier is being asked to deliver
power beyond its ability.

• Infinite baffle or “free air”
mounting applications allow for
greater cone excursion than sub­woofers mounted in an enclosure.
In order to compensate, recognize
that the power-rating value of the

subwoofer will likely be half its
rated power in this application.

• Study the excursion curves on
the enclosed GT Series data
sheet and note the differences
for different enclosure applica­tions. The type and size of box
used will produce different excur­sion demands on the enclosed
subwoofer and, consequently,
different levels of power han­dling. As long as recommended
parameters are used, the sub­woofer will perform properly in
its enclosed environment.

However, any design deviation
may result in less than optimum
performance, and may also
subject the subwoofer to over­excursion that can eventually
damage the speaker. For
additional help with this issue,
please contact your authorized
JBL dealer.

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Declaration of Conformity

We, JBL Europe A/S

Kongevejen 194B
DK-3460 Birkerød
DENMARK

declare in own responsibility, that the products described
in this owner’s manual are in compliance with technical
standards:
EN 50 081-1/1992
EN 50 082-1/3.1995

Steen Michaelsen

JBL Europe A/S

Birkerød. DENMARK. 2/98

JBL Consumer Products
250 Crossways Park Drive
Woodbury, NY 11797

8500 Balboa Blvd.
Northridge, CA 91329
800-336-4JBL (4525)
www.jbl.com

Part No. GTAUTOSUBOM
Made in USA