JBL Project EVEREST DD66000 Brochure & Specs - page 15
With a 25mm (1") pure-beryllium diaphragm and 50mm (2")
neodymium magnet structure, the ultrahigh-frequency 045Be-1 is
considerably smaller than the high-frequency 476Be.
The pure-beryllium diaphragm is less than 0.04mm thick and has a
mass of only 0.1 gram. The single-layer aluminum-ribbon voice coil
is wound without a former and is attached directly to the diaphragm.
The driver employs the smallest annular-slit phasing plug that JBL
has ever designed.
The ribbed structure of the die-cast aluminum back cover contributes
to the driver's high rigidity and efficient heat dissipation. Back
pressure from the diaphragm is effectively absorbed and controlled
to prevent subtle internal vibration, ensuring pure resonance-free
reproduction of supersonic frequencies.
The moving system’s extremely low mass and high magnetic-flux
density combine with the high rigidity of beryllium to produce
superb response that is very smooth from above 8kHz to beyond
50kHz.
The SonoGlass Bi-Radial horn is scaled to achieve constant
directivity, maintaining a coverage angle of 60 degrees in the
horizontal plane and 30 degrees in the vertical plane over the
frequency range from 10kHz to 50kHz.
With a 100mm (4") pure-beryllium diaphragm, a 100mm (4")
aluminum edge-wound voice coil and a rapid-flare, coherent-wave
phase plug, the 476Be high-frequency driver delivers astonishing
high-end performance with minimal distortion and power
compression, even at the highest output levels.
The diaphragm is formed of pure beryllium foil, manufactured with
a proprietary high-temperature, pressure-forming process. This
process enables the integrated JBL diamond-pattern surround to be
formed as one piece with the dome. Compared to other methods,
forming the diaphragm out of sheets of beryllium foil yields greater
reliability and resistance to failure due to fatigue.
Pure beryllium has proven to be superior to aluminum, magnesium,
titanium and other premium diaphragm materials. Because of its
far greater stiffness-to-density ratio, it responds to the highest
frequencies with more precise and consistent pistonic action and
resists modal breakup better than any other widely used material.
In place of a conventional copper-plated polepiece, the 476Be
combines a powerful neodymium rare-earth motor structure with
an innovative, high-purity copper-sleeved polepiece to maintain
gap flux and significantly enhance electrical conductivity without
compromising on size and weight. Better conductivity directly
translates into lower coil inductance, more effective heat dissipation,
reduced dynamic power compression and greater output at
frequencies of 15kHz and above.
The 476Be’s unique coherent-wave phasing plug is precision-die-
cast of zinc to ensure dimensional and structural stability under
high heat and acoustic pressure. The four-slot coherent-wave design
shapes the wave output to deliver a true coincident wave front to
the Bi-Radial
®
horn, producing exceptionally smooth frequency
response and reducing secondary harmonic distortion by up to 6dB,
relative to earlier designs.
The neodymium magnet
assembly maintains a
minimum gap-flux density of
approximately 18,000 gauss
476BE High-Frequency Driver and Horn
045BE-1 Ultrahigh-Frequency Driver and Horn
476Be High-Frequency Driver
045Be-1 Ultrahigh-Frequency Driver
Coherent-wave 4-slot phase plug
Foam damping pad
Copper-sleeved polepiece
Front plate
Die-cast aluminum front cover
Beryllium diaphragm assembly
Acoustic seal
Die-cast aluminum back cover
5-Way gold-plated terminals
Top plate
Neodymium magnet
Back plate/driver exit
Stainless-steel mounting bracket
25mm Edge-wound aluminum voice coil
Phase plug
25mm Pure-beryllium diaphragm
Neodymium magnet
Top plate
Die-cast aluminum-alloy back cover
Gold-plated input terminals