CHAPTER 1 – THE S4800 LOUDSPEAKER:
A TRIUMPH IN ACOUSTICS AND TECHNOLOGY
The new S4800 employs a 3-way, three-driver design, incorporating an ultrahigh-frequency (UHF) com- pression driver and horn to repro- duce high frequencies up to 40kHz. With the UHF handling the ultrahigh frequencies, the high-frequency (HF) transducer could then be upgraded to a new design using a
3-inch diaphragm for better repro- duction of lower frequencies and better blend with the woofer than the older generations’ 2-inch diaphragm. Both compression
drivers are mounted in a unique combination Bi-Radial®horn struc- ture, precision-molded from JBL’s proprietary SonoGlass™ material, an extremely dense and mechanically inert substance that is easily molded into the unusual shapes required for superior acoustic performance.
In order to re-create the extremely high dynamic range provided by today’s audio sources, a new low- frequency transducer was used, incorporating a ferrite magnet, 3- inch edge-wound voice coil, and an Aquaplas-coated 15-inch cone made of Kevlar® composite, a mix- ture of Kevlar fiber and pulp mate- rial that provides increased rigidity. An EPDM rubber surround was chosen for both its flexibility and long life. The Symmetrical Field Geometry™ (SFG™) magnetic struc- ture minimizes second harmonic distortion by providing a uniform flux field that prevents uneven
i 1"045UHF |
Compression |
Driver |
435AL |
3" HF |
Compression |
Driver |
SonoGlass |
Bi-Radial Horn |
100˚ Horizontal |
60˚ Vertical |
1500FE |
15" LF |
Driver |
1" MDF |
Construction |
Port |
ubeT |
Curved |
Dress |
Panel |
Spiked Feet
Foot Base
cone movement. The rigid cast- aluminum frame is also designed to minimize distortion, as alu- minum has no effect on the mag- netic field. Extensive computer- aided engineering and design effort made to develop the optimized port tuning employed in the S4800 has resulted in a significant advance in the concept of state-of-the-art bass reproduction. This proprietary align- ment method offers the best damp- ing characteristics and provides extremely fast alignment, eliminat- ing the typical “bass-reflex” sound of a ported system.
All three transducers are built using the most advanced materials and precision manufacturing techniques refined from renowned JBL profes- sional sound systems.
High power-handling capability results in no limitations on the types of source material. The S4800 has very high input sensitivity; even a relatively small high-end amplifier can provide full dynamic range without compression.
Despite its power and sophistica- tion, the S4800 embodies both tradi- tion and technology. It reflects the design, engineering and manufac- turing expertise derived and refined through nearly six decades of experience that are the exclusive province of one loudspeaker builder – JBL.
Figure 1. Cutaway view of S4800 speaker system.
