JBL 4642A Dual 460mm (18") Subwoofer System, 4 ohms Rated Impedance, 4800 Watts Peak Power

The JBL 4642A is a high quality subwoofer system, featuring an advanced technology 460 mm (18"), low frequency transducers mounted in a direct radiator, bass-reflex enclosure for smooth response to the lowest audible frequencies. The 4642A is ideal for low-frequency augmentation of either analog or digital soundtracks in motion picture theaters and for general sound reinforcement applications.

The 2241H transducer utilizes the patented Vented Gap Cooling (VGC) process, which pumps air through the magnetic gap and directly over and around the voice coil, providing immediate heat transfer and a reduction in operating temperature. This increases power handling while reducing power compression.

Through the use of computer-aided magnet optimization and analysis techniques, JBL has optimized magnet weight, flux density and field saturation, resulting in a 2.6 kg (6.5 lb) reduction in overall driver weight and a significant reduction in harmonic distortion. This magnet structure offers much of the weight advantage of rare earth magnet structures, enabling the system to carry a 1200 watt continuous AES pink noise power rating.

The 100 mm (4") voice coil benefits from a new winding technique, which offers greater thermal stability with increased power handling. All elements of the cone, voice coil and suspension system have been carefully optimized and controlled to ensure smooth high frequency response. The magnet structure and compliance allow for long peak-to-peak excursions without damage to the speaker. Symmetrical Field Geometry (SFG) minimizes second harmonic distortion.

The enclosure is constructed of dense stock and is extensively braced on all panels. It has a net internal volume of 506 liters (18 cu. ft.) and is tuned to 25 Hz with a very large port to minimize port compression and to reduce distortion due to turbulent air flow. The 4642A features high sensitivity. It is intended for use as a subwoofer with a low-pass filter and appropriate high-pass filtering for protection and equalization.