JBL Synthesis K2 S9900 - Manual (Page 17)

Project K2 S9900
17
Another benefit of the magnesium alloy is the greater internal loss, or damping,
when compared to titanium or even aluminum. This greater internal loss
quickly minimizes the amplitude of resonances when the diaphragm is asked
to reproduce frequencies beyond its pistonic limit. To further augment this
damping, a very light application of JBL Aquaplas is also used. Combining the
greater internal loss with the stiffer characteristics of the thicker, low-density
material, this new 100mm magnesium-alloy dome sonically performs close
to the beryllium diaphragm used in the 476Be high-frequency Project Everest
drive unit, but at a fraction of the cost. In the end, careful optimization of this
new magnesium-alloy diaphragm’s characteristics, along with the application
of Aquaplas damping, has maintained the enhanced detail of musical transients
and microdynamic nuances to which JBL listeners have become accustomed.
Figure 5. Terminated tube measurement of 476Mg with distortion products. The
measurement was made with 7.5V applied to the driver. This equates to about
120dB @ 1m when mounted in the system.
045Be-1 Ultrahigh-Frequency Compression Driver and Bi-Radial Horn
Like the original 045Be, the 045Be-1 uses a 1-inch (25mm) beryllium
diaphragm and 2-inch (50mm) neodymium magnetic structure. 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 engineers have ever designed. The 045Be-1 has been
designed to improve manufacturing yield and consistency. Small changes have