The 404 and 504GTi Woofer/Midrange
Drivers incorporate advanced JBL woven
Kevlar cones which are especially suited
to the unique acoustic and environmental
conditions which characterize automotive
sound. The 20mm tweeter incorporates
advanced JBL pure titanium technology
which works extremely well in the
unique acoustic environment of modern
vehicles. The 404 and 504GTi 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.
Treated Kevlar fiber cones are used
because of their combination of low
weight, high stiffness and resistance to
resonances. The 404 and 504GTi
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 woofer/midrange designs is
controlled by a Aromatic Polyamid fiber
spider. Because it is 3 times stronger than
conventional spider materials, this robust
material is able to control the up to 0.6"
motion of the cone while maintaining
musical accuracy.
The small size of the GTi Woofer/
Midrange Drivers is made possible
through the use of a Neodymium magnet
assembly with JBL’s Stray Field
Containment Geometry. By 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 High Temperature Fiberglass Voice
Coil. This 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. The tweeter
uses Oxygen Free Copper wire immersed
in a thermally conductive bath of viscous
Ferrofluid
TM
. This fluid not only conducts
heat away from the voice-coil to improve
power handling, but damps the
fundamental resonance of the dome for
optimum sound.
The tweeters in the 404 and 504GTi
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 404 and 504GTi 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 404 and
504GTi 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 404 and 504GTi Crossovers was
performed with a full knowledge of the
performance characteristics of each driver,
allowing frequency, phase, and power
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