JBL Century Gold - Manual (Page 6)

The
Century Gold
also features an all-new 5" (127mm) mid-frequency
transducer developed specifically for the
Century Gold
(Figure 2). The
voice coil is 2" (50mm) in diameter and wound on edge from flat aluminum
ribbon wire to a depth of precisely .4" (11mm) on a thermoset composite ™
form. The cone is made of Kevlar ® with a composite rubber/vinyl surround.
Kevlar was chosen for the cone material because it is extremely strong and
rigid while relatively low in mass. This allows the driver to move fast
enough to reproduce the dynamics of the critical midrange frequencies while
retaining the low distortion characteristics necessary for accurate musical
reproduction. Its very high power capability and freedom from breakup
make it an ideal midrange in a system that is designed to play at high levels
with absolutely no signs of distress. It makes the transition from the woofer
at 600Hz, providing good dispersion throughout the important vocal range.
Throughout the history of high-frequency transducer design, the goal of
extended frequency response has been at odds with the need for high
power handling. JBL has long chosen titanium as the material for its
highest quality high-frequency transducers and the
Century Gold
is
no exception (Figure 3). Titanium possesses the essential requirements for
a high-frequency transducer. First, titanium is extremely light yet rigid.
The goal is to maintain a piston-like action as high in frequency as possible.
If the material flexes easily, the diaphragm will break up into random
vibrations. Second, titanium is virtually free from fatigue. The material
is virtually immune from the cumulative effects of millions of flexures
over long operating periods. These factors, coupled with the higher power
handling that titanium affords, allow us to produce an extremely smooth
high-frequency transducer with extended frequency response that can handle
all the demands of today’s digital programs.
High-Frequency Transducer
No.
4
1 " copper
voice coil
provides
smooth
performance
and high
power
handling Cast zinc faceplate
for less resonance
Titanium dome
Figure 3 050 Gold
High-Frequency Transducer
Mid-Frequency Transducer
Diecast aluminum frame
for high strength
Rubber/vinyl
surround
Vented pole piece allows
driver to run cooler
Neodymium magnet provides
high flux density with low mass
0.4" (11mm) long,
2" (50mm)
diameter edgewound
aluminum voice coil for
high linearity and
power handling
Kevlar
cone
Figure 2 Century 500
Mid-Frequency Transducer
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