JBL 4638 Low Frequency Woofer Speaker System, Two 15" Transducers, 4 ohms Impedance

The JBL 4638 low frequency system is designed for cinema use and general reinforcement where smooth power response and accurate reproduction are essential. The 4638 employs the latest in JBL low frequency transducer technology, offering exceptional performance benefits.

The JBL 2035H 380 mm (15") transducer employs a copper-sleeved magnetic pole piece, which reduces internal flux modulation and provides a more stable magnetic field. This substantially lowers both second and third order harmonic distortion.

The copper-sleeved pole piece design of the 2035H also creates a flatter impedance curve, resulting in a nearly perfect resistive load throughout the operating range of the transducer and producing a more constant power response characteristic below 1 kHz.

This helps maintain a smoother and more natural sounding power response transition between the low and high frequency devices in the crossover region, resulting in, among other benefits, more accurate reproduction of dialog throughout the listening area. The 2035's voice coil operates in a large Symmetrical Field Geometry (SFG) magnet structure to further reduce harmonic distortion to inconsequential levels.

With a sine wave input of 100 watts, third harmonic distortion is no greater than 1% and second harmonic distortion is no greater than 0.8% at any frequency between 100 Hz and 500 Hz. The enclosure is constructed of dense stock and is extensively braced on all panels. Net internal volume is 225 liters (8 cu ft) and the enclosure is tuned to 40 Hz. Port area is large, ensuring minimum turbulence at full input at low frequencies.