JBL 4425MKII

Commentary

A refined model of the 4425 released in 1985.
While keeping the original design concept as it is, we technology accumulated through the development of Project K2 and 4344 MKII is introduced.

1200H, a 30 cm cone type unit, is used for the low range.
K2 series technology has been introduced, and fiber composite cone made by mixing glass fiber with pulp paper is adopted.
In addition, by applying a unique Aqua Plus coating on the surface of the cone, both the rigidity that suppresses the generation of split vibration and the damping effect that smoothly connects sound in the crossover region are achieved.
In addition, a 3-inch diameter, edgewise wound voice coil and newly designed large damper are adopted to improve linearity and power handling.
In addition, by creating a symmetric magnetic field in the voice coil gap and using an SFG (symmetrical filtered geometry) magnetic circuit that reduces second harmonic distortion, we have achieved medium and low frequency characteristics with less distortion.
The frame uses a high-strength aluminum die-cast with a direct penting system that efficiently releases the sound pressure to the rear of the suspension.

A 2-inch 175 nd compression driver and a bi-radial horn are used for the high frequency band.
The driver is equipped with a pure titanium diaphragm, and by adopting a unique diamond structure edge, resonance between the diaphragm and the edge is eliminated to ensure free movement of the diaphragm.
In addition, it is stored in the back housing made of high-strength aluminum die-cast, and the back pressure of the diaphragm is well received.
The magnetic circuit is equipped with a high-flux neodymium magnet and has an inner magnetic structure with high magnetic conduction efficiency. In addition, a Ferrofluid cooling mechanism is used to inject magnetic fluid into the voice coil gap to effectively dissipate the heat generated in the voice coil, thereby increasing the input resistance.

The horn section is equipped with a new-generation bi-radial horn that provides 100 ° constant directivity in both horizontal and vertical directions over a wide band. It can be applied widely from near distance monitoring to middle distance monitoring.
A special resin is used for the horn material. Through analysis and processing using a computer, the shape and thickness of the horn are precisely controlled in details from the throat to the opening, and a high degree of perfection has been achieved by eliminating horn squeal and coloring.

Based on the biased network technology established in the K2 Series, it employs a high-quality dividing network composed of carefully selected passive parts.
It is equipped with a low-frequency network with high transient characteristics and a high-frequency network with serial / parallel combinations of capacitors. The low-frequency network is equipped with multiple capacitors with different dielectric constant and structure in parallel to eliminate inherent colorization. The high-frequency network is equipped with a combination of capacitors in series / parallel.
In addition, the separate arrangement of independent boards eliminates electromagnetic coupling between networks.
In addition, we have succeeded in eliminating 0 cross distortion and improving sound resolution and transient characteristics by adopting a charge-coupled linear definition method that adds DC bias to the high-frequency network and making the capacitor perform class A operation.

It is equipped with a continuously variable network capable of adjusting the high frequency level.

The high-frequency and low-frequency gold-plated speaker inputs allow for bi-wiring connection and bi-amplifier drive.

The enclosure is grouped in the same baffle size and floor size as the 4425 for ease of replacement.
A 19 mm thick particle board is used for the material, and reinforcement is placed inside.
MDF material is used for the baffle plate, smooth curved surface is applied to the opening of the bass reflex port, and finished with gray black paint of the same color as horn.
In addition, with an emphasis on interior design, the exterior is finished with a 5-sided wallnut board.

Model Rating

Method	2-Way, 2-Speaker, Bass Reflex System, Bookshelf Type
Units, etc.	For Low Band : 30 cm Cone Type (1200H) For high pass : 5 cm screwdriver (175 nd) + 1 inch throat by radial horn
Frequency characteristic	35 Hz to 20 kHz -6dB
Output sound pressure level	91dB/W/m
Impedance	8 Ω
Allowable input	200W (continuous program) 800W (peak)
Crossover frequency	1100Hz(12dB/oct)
External dimensions	Width 409x Height 635x Depth 313/360 (Including Horn) mm
Weight	25.8kg
Sold Separately	Speaker Stand JS-50 (1 unit, ¥ 25,000)