JBL4425 monitor loudspeakers

Bi-Radial Studio Monitor

The success of the models 4430 and 4435 Bi-radial studio monitor loudspeakers has prompted JBL to introduce a smaller model based on the same principles for use in smaller studios and for a variety of demanding audio production applications.

As in the case of the larger Bi-Radial monitors, the 4425 maintains a 100-degree-by-100-degree coverage pattern from its crossover frequency (1200 Hz) up to 16 kHz. Smooth power response is ensured from the lowest frequencies up to 1200 Hz, and flat power response is maintained above that frequency. At the same time, axial response is remarkably smooth, and the combination of controlled power and axial response ensures that the reflected sound field in the control room will be free of coloration. The model 4425 also addresses the requirement for accurate stereophonic imaging. The mirror imaged pair creates absolutely symmetrical sound fields, and this is the essential requirement for precise imaging. There is no lobbing for normal off-axis listening positions in the horizontal plane, and vertical lobbing is minimized over the preferred listening arc.

The model 4425 can handle program power inputs of 200 watts, more than enough to accommodate the high acoustical levels demanded in critical listening to today's digital recordings.

 

High-Frequency Horn and Driver

The BI-Radial horn used in the model 4425 is a scaled down version of the model 2344 horn used in the 4430 and 4435 monitor loudspeakers. It is made of high-impact structural foam and is acoustically inert. The high-frequency compression driver is a completely new design making use of a computer-machined phasing plug. Tolerances are held to a high degree, and unit-to-unit variation is small. The disphragm assembly is JBL's unique titanium design, with its advantages of extended frequency response relative freedom from mechanical fatigue, and high acoustical output capability. A copper shorting ring plated on the pole piece controls high-frequency impedance and improves high-frequency response.

As is the case with the larger Bi-Radial monitors, the 4425 system maintains precisely aligned phase response over a forty-gegree wide arc in the horizontal plane. The preferred listening arc in the vertical plane is between zero (on-axis) and ten degrees up.

 

Low-Frequency Transducer

A newly designed driver, the model 2214H, is used in the 4425 monitor loudspeaker. This transducer incorporates JBL's symmetrical field geometry (SFG) magnet structure for low distortion. The 76 mm (3-in) voice coil is made of edge-wound copper ribbon wire for highest sensitivity and power handling. The inner suspension of this transducer has been designed to exhibit a progressive increase in restoring force with increasing displacement. This controls dynamic offset for low-frequency, large excursion signals, and results in reduced distortion at low frequencies. A composite coating on the cone optimizes both damping and stiffness, resulting in smoother response and lower distortion.

 

Frequency Dividing Network

In addition to the normal function of frequency division, the network in the 4425 provides power response compensation for the high-frequency drier. Two controls allow the user to contour both mid and high frequencies to match various room characteristics. While the network slopes are 12 dB/octave, the combination of inherent roll-off characteristics in both high- and low-frequency components of the system with the electrical characteristics yields quite rapid transitions in the crossover frequency. Network components are of the most rugged, low-loss type, and high-quality bypass capacitors are placed in parallel with the larger capacitors in the signal path for increased linearity.

 

Specifications

Frequency Response:  40 Hz - 16,000 kHz ±3 dB

Sensitivity:  91 dB SPL

Efficiency:  0,8%

Dispersion Angle

Horizontal :  100° (+10°; -30°)

Vertical :  100° (+0°, -30°)

Impedance:  8 Ω  nominal

Max. Power Input:  200 W

Continuous Sound Pressure Level:  114 dB

Crossover Frequency:  1,200 Hz

Driver Complement:

Low Frequency :  2214H

Compression Driver :  2416H

Horn :  2342

Enclosure Volume:  53,8 l (1,9 cu. Ft.)

Resonance Frequency:  34 Hz

Dimensions:  406 x 635 x 311 mm (375 mm deep w/horn)

Weight Net:  26 kg (57 lbs)