JBL 408GTI, Installation Manual

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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
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 work-
hardening 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 state-
of-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? A system 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 Your 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
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