JBL 508GTI User Manual
408GTi 508GTi
AUTOMOTIVE NEO/KEVLAR MATCHED
COMPONENT SYSTEM WITH CAST FRAME
INSTALLATION GUIDE
Table of Contents
Welcome to Club GTi.........................................................................3
About this Manual ..............................................................................3
Autosound at its Best .........................................................................3
Designing Your System......................................................................4
Component Placement.......................................................................5
Installation Warnings and Tips ...........................................................5
Mounting Instructions.........................................................................6
Installing the GTi System Crossover..................................................6
Woofer/Midrange Driver Mounting .....................................................7
Mounting the 408 and 508GTi Tweeter..............................................8
Tweeter Surface Mounting Instructions..............................................8
Tweeter Surface Angle Mounting Instructions....................................9
Tweeter Flush Mounting Instructions ...............................................10
Tweeter Flush Angle Mounting Instructions......................................11
Wiring...............................................................................................12
Crossover Tweeter Level Adjustment...............................................12
System Connections ........................................................................13
Speaker Break-In .............................................................................14
A Note on Power Handling ...............................................................14
In Case of Difficulty ..........................................................................14
Specifications...................................................................................16
Thiele-Small Specifications..............................................................17
Mounting Templates.........................................................................19
2
Welcome to Club GTi
About This Manual
Autosound at its Best
Thank you for purchasing the finest
Automotive Component Systems JBL has
ever produced. As a GTi Competition
Series owner, you are a member of a
select group of people who enjoy the most
advanced mobile audio products available.
We call this group “Club GTi.” By sending
in the customer information card, which
you will find attached to your warranty, we
will automatically register you as a Club
GTi member which will give you access to
exclusive Club GTi apparel and other
special offers we will make available from
time to time. We suggest you fill the card
out at your earliest convenience.
Also, be sure to save your sales
receipt in a safe place. It will be necessary
to use this document as proof of purchase
in the event that you ever need warranty
service. It is also useful for insurance
purposes and for establishing value when
you re-sell your vehicle.
Because of the performance capability
of your GTi Competition Series product,
and the variety of potential system
configurations, we strongly recommend
that you have the system professionally
installed. You will also get a better warranty
if your equipment is professionally installed
by an authorized GTi dealer and you have
your warranty card stamped. This manual
provides information on installation and
usage to help a skilled technician get the
most from your GTi Competition Series
product. This manual does not cover basic
information about installation which is
common knowledge to a professional
installer, except for information which is
unique to the 408 and 508GTi systems.
If you feel you possess the necessary
skills, and prefer to install the equipment
yourself, this manual will provide you with
the necessary specifics to properly use the
408 or 508GTi in typical installations.
Consult your JBL dealer, or a qualified
technician, for more information.
The 408 and 508GTi systems are built
to meet the same rigorous standards of
construction and performance that have
long established JBL’s renowned home
and professional speaker systems. The
408 and 508GTi Woofer/Midranges
incorporate advanced JBL woven Kevlar
cones which are especially suited to the
unique acoustic and environmental
conditions which characterize automotive
sound. The 408 and 508GTi Tweeter
incorporates advanced JBL pure titanium
technology which is especially suited to
the unique acoustic environment of
modern vehicles. The 408 and 508GTi
have been engineered to provide excellent
power handling, good dispersion and
balanced frequency response, along with
minimum size and flexible installation
options for optimizing placement within the
vehicle.
The small size of the GTi Drivers is
made possible through the use of a
Neodymium magnet assembly with JBL’s
Stray Field Containment Geometry. By
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minimizing stray magnetic fields, this
closed circuit magnetic assembly design
concentrates the magnetic field on the
voice coil where it provides superior
performance. In the woofer/midrange
drivers, this high concentration of magnetic
power is coupled to a 2" Edge-wound
Aluminum Wire Voice Coil on a High
Temperature Fiberglass Former . This voice
coil uses lightweight aluminum wire to
maintain the agility to reproduce high
frequencies while its large diameter and
fiberglass former assures extremely high
thermal power handling.
Treated Kevlar fiber cones are used
because of their combination of low
weight, high stiffness and resistance to
resonances. The 408 and 508GTi
Woofer/Midranges are topped off with a
treated fabric inverted dome for smooth
reproduction of upper midrange
frequencies.
The cone motion of these high
excursion designs is controlled by a
Aromatic Polyamid Fiber Spider. This new
material is able to control the 0.6" motion
of the cone while maintaining musical
4
accuracy because it is 3 times stronger
than conventional spider materials.
The tweeters in the 408 and 508GTi
feature domes made from pure titanium.
Pure titanium has long been known to have
a very high stiffness to weight ratio, making
it ideal for treble reproduction. However,
only JBL has “tamed” titanium through a
special manufacturing process. The dome
of the 408 and 508GTi Tweeter is created
using special nitrogen gas cooled forming
machines which can create a uniformly
paper-thin dome without the workhardening or deformation which causes
resonances in domes made without benefit
of this process
Equally important is the 408 and
508GTi crossover design. Each crossover
was meticulously optimized in JBL’s stateof-the-art acoustic laboratory to guarantee
a seamless blend of the woofer/midrange
and tweeter output. Unlike generic or
general purpose crossovers, the design of
the 408 and 508GTi Crossovers was
performed with a full knowledge of the
performance characteristics of each driver,
allowing frequency, phase, and power
response to be completely optimized for
each combination.
What does all this technology add
up to? Asystem with ideal frequency
response, excellent off axis response,
and high output capability all in a small
and elegant package. The result is
exceptionally smooth and detailed music
reproduction over the full range of
frequencies and clean sound that cuts
through road noise.
Designing Y our System
The overall quality of any system
design is a result of how well all of the
components work together, not just the
result of the performance of any one
component. JBL GTi Series woofer/
midbass or subwoofer transducers are
the ideal companion products to your 408
and 508GTi systems. Each of the GTi
Competition Series products are designed
to complement the others to provide the
highest performance with the simplest and
most predictable system design. To use the
408 and 508GTi as the woofer/midrange
and high frequency transducers in a high
quality system, we recommend you use
either a high quality active crossover
such as JBL’s GTX47, GTX4 or GTX2
to provide optimum matching to your
subwoofer or woofer/midbass loudspeaker.
If you prefer passive crossovers, we
recommend that you use only high quality
audiophile grade film-type capacitors
and Low DCR inductors to get the most
out of your system. The most popular
system configuration is a hybrid using
an active crossover for the subwoofer to
woofer/midrange crossover point, and a
passive crossover for the woofer/midrange
to tweeter crossover. Your GTi Competition
Series Dealer is uniquely qualified to help
guide you on the best system configuration
for your needs.
Component Placement
The location of each of the
loudspeakers plays a vital role in achieving
proper frequency response and spacious
imaging. Because the 408 and 508GTi
systems have an extremely wide and
smooth dispersion pattern, excellent
performance may be achieved in any
vehicle. Due to the wide variety of vehicles,
there is not one “right” way to locate the
408 and 508GTi, however knowledge of
the following considerations will help you
get the most from your system:
1. The most spacious stereo image is
achieved when the speakers are placed
as wide apart as possible.
2. The best center image will be achieved
when the distance from the left speaker
to your left ear is as equal as possible to
the distance from the right speaker to
your right ear. This is most easily
achieved by placing the 408 or
508GTi as far forward as you can.
3. The best system integration is achieved
when the woofer/midrange is mounted
close to the tweeter. Installing the
tweeter close to the woofer/midrange
helps smooth the transition from
woofer/midrange to tweeter at the
crossover point.
4. Y ou will get the best frequency
response when the path from the
speakers to your ear is unobstructed.
5. Because of the high acoustic energy
capability of the 408 and 508GTi, the
woofer/midrange drivers must be
securely mounted in a rigid panel which
is free from resonances, rattles and air
leakage.
Installation Warnings and Tips
• Be careful not to cut or drill into fuel
tanks, fuel lines, brake or hydraulic
lines, vacuum lines or electrical wiring
when working on your vehicle. Inspect
behind panels before you cut or drill.
• Be sure to check for clearance of
window, cranks and linkages when
mounting speakers in door panels.
• Do not use the speakers unmounted.
Failure to securely mount this product
could result in damage or injury,
particularly in the event of an accident.
• Although the materials used on the 408
and 508GTi are inherently water
resistant, do not mount the speakers
where they will get wet.
• Always disconnect the ground wire
from the battery before doing any work
on the vehicle.
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Mounting Instructions
Pick a mounting location after reading
the recommendations in the Component
Placement section of this manual.
Installing the GTi System
Crossover
The GTi system crossover should be
mounted securely to prevent damage to
the crossover or possible loosening of
wiring connections. Choose one of the
crossover mounting methods and follow
the directions below:
2. Remove the crossover board from the
plastic case.
3. Use wire ties to secure the plastic case
to the desired location as shown in
Figure A.
4. Cut off the excess plastic on the wire ties.
5. Re-install the PCB and install wiring
from the crossover to the amplifier
and speaker locations as shown in
Figure K.
6. Re-install the crossover cover.
Figure B
3. Mark 4 hole locations, drill holes and
secure the bottom cover to the desired
mounting location as shown in Figure B.
Before starting make sure no electrical
or other critical car components are
located where you will be drilling.
4. Re-install the PCB and install wiring
from the crossover to the amplifier
and speaker locations as shown in
Figure K.
5. Re-install the crossover cover.
Note: Do not mount the GTi Crossover in a
location where it can get wet, as this
may cause damage to its components.
MOUNTING RING
ADAPTER
Figure A
Mounting the GTi Crossover with Wire Ties
1. Remove the crossover cover as shown
in Figure L.
6
Mounting the GTi Crossover with Screws
1. Remove the crossover cover as
shown in Figure L.
2. Remove the crossover board from the
plastic case.
Figure C
WOOFER/
MIDRANGE
Woofer/Midrange Driver
FABRIC
DISPLACEMENT
RING
WOOFER/
MIDRANGE
Mounting
Mounting the Woofer/Midrange to
Stock Hole Locations
1. Access the stock speaker location and
remove the stock speaker. The 408
and 508GTi include mounting ring
adapters which allow the speaker to
be mounted in standard 4" and 5
holes respectively.
2. Attach the mounting ring adapter to
the stock location using four #8 x 1
screws as shown in Figure C.
3. Attach the foam gasket to the back of the
woofer/midrange. Connect the speaker
wire from the crossover terminals marked
“W” to the speaker by either soldering
(preferred) or using crimp terminals.
Connect the wire from the “W+” terminal
on the crossover to the red “W” terminal
on the woofer/midrange. Repeat the
same process for the “W–” terminal (see
Figure K for details).
4. Mount the woofer/midrange driver to
the adapter ring using three #8 x
screws and three shoulder washers
as shown in Figure C.
5. Replace the stock speaker panels.
5
Mounting the Woofer/Midrange in
Custom Locations
2. Cut out the speaker hole at the
mounting location and drill the three
marked holes with a
1
/8" (3mm) drill.
3. Run speaker wire to the hole location,
making sure that either an active or
the included passive crossover is
connected to the speaker (see Figure K
for wiring details).
1
/4"
4. Put the speaker Fabric Displacement
Ring under the speaker as shown in
Figure D.
1
/4"
Figure D
5. Attach the foam gasket to the back of the
woofer/midrange. Connect the speaker
wire from the crossover terminals marked
“ W” to the speaker by either soldering
(preferred) or using crimp terminals.
1. Snap the grille assembly of the speaker
onto the driver and choose three hole
locations so that the grille logo is oriented
as desired for your installation. Use the
Fabric Displacement Ring included in the
package to mark the location of the three
screw holes and the speaker cutout
holes (cutout hole sizes are listed in the
/8"
Specifications section). Before cutting or
drilling make sure that there are no car
components, electrical wiring or any
other items that could be damaged.
Connect the wire from the “W+” terminal
on the crossover to the red “W” terminal
on the woofer/ midrange. Repeat the
same process for the “W–” terminal (see
Figure K for details).
6. Mount the speaker to the hole location
1
using three #8 x 1
/4" screws and three
shoulder washers as shown in Figure D.
7. Push the grille down onto the speaker
making sure the tabs on the speaker
match with the slots in the grille. Twist
1
the grille about
/2" (12mm) clockwise to
lock the grille into place.
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