JBL Synthesis K2 S9900 - Manual (Page 15)

Project K2 S9900
15
A thick-wall, cast-aluminum frame is used to rigidly support the motor
structure. This fully vented frame and motor design also serves to minimize
the back pressure under the dome and spider, helping to reduce harmonic
distortion to even lower levels. Proprietary JBL Vented Gap Cooling
™ (VGC) is
incorporated within the motor structure, and lowers the operating temperature
of the coil during moments of high-power operation.
All together, these design factors provide reduced harmonic distortions at
very low and very high acoustic output, improved power handling, reduced
power compression and more consistent spectral balance, with varying input
drive level.
476Mg High-Frequency Compression Driver and Bi-Radial ® Horn
The 476Mg high-frequency compression driver makes use of a 4-inch
(100mm)-diameter, magnesium-alloy diaphragm with a 4-inch (100mm)
aluminum edge-wound coil, operating into the JBL existing rapid-flare-type,
coherent-wave phasing plug. The use of an efficient neodymium rare-earth
motor structure with a new copper-sleeved polepiece maintains maximum gap
flux and reduced coil inductance at a minimal size and weight. The combination
of these features has resulted in a driver that can deliver superior sound quality,
regardless of acoustic power output, with very little distortion and power
compression (Fig. 4).
Back Plate
Neodymium Magnet
Copper-Sleeved Pole
100mm Aluminum
Edge-Wound Coil
Gap: Acoustic Seal and
Resonance Tuning Ring
Die-Cast Aluminum
Front Cover
Coherent-Wave, 4-Slot
Phase Plug
Top Plate
Die-Cast Aluminum
Back Cover
5-Way, Gold-Plated
Terminals
Diamond Surround
Foam Damping Pad
Magnesium-Alloy
Diaphragm Assembly
Figure 4. 476Mg section view.