Designed and engineered in JBL’s world-famous acoustic engineering facility in Northridge, California, the 4309 Studio Monitor is a showcase of patented JBL acoustics technologies. This bookshelf loudspeaker features a 2-way design with patented High-Definition Imaging (HDI™) horn technology, the patented 2410H-2 1-inch (25mm) compression driver, and a 6.5-inch (165mm) cast-frame, Pure-pulp cone woofer for powerful dynamics and incredibly accurate sound reproduction.
JBL’s revolutionary High-Definition Imaging horn geometry is the result of intense research into the nuances of horn design. In search of exceptional high-frequency detail and uniform directivity for smooth in-room response, JBL engineers pioneered a design that delivers neutral frequency response both on- and off-axis and provides a seamless transition between the high and low frequency drivers.
The JBL 2410H-2 compression driver benefits from the advanced research and applications derived from JBL Professional’s “D2” range of transducers. At the core of the 2410H-2 device is a lightweight polymer, annular diaphragm that improve high-frequency extension by reducing diaphragm mass. The V-shaped geometry of the annular diaphragm reduces breakup modes, eliminating time smear and reducing distortion. The result is incredible dynamics with accurate reproduction and a lack of power compression.
An Ultra High-frequency tonal adjuster is located on the front panel below the horn and allows the sound to be tailored to the specific environment and listener preference. This control works in conjunction with an advanced crossover network design that features air-core inductors, cast wire-wound resistors and low-ESR metallized film capacitors to optimize the performance of the 4309 drive components.
The 4309’s powerful 6.5-inch (165mm) woofer takes advantage of core JBL engineering techniques to ensure very high output with low distortion. The long-throw voice coil in conjunction with the symmetrical field motor design, flux stabilization ring, and copper shorting ring guarantee maximum output with low distortion. A Pure-pulp cone provides a lightweight, rigid diaphragm and helps to eliminate breakup modes ensuring proper pistonic motion throughout the operating band.
The 4309 enclosure is heavily braced with 3/4-inch (18mm) thick walls to provide a solid acoustic foundation and incorporates a bass reflex design with dual front-firing, computer-optimized flared ports. The cabinet features a classic JBL studio monitor design with a blue baffle and is finished in a choice of Walnut or Black Walnut furniture-grade satin wood veneers. A blue (Walnut) or black (Black Walnut) cloth grille completes the elegant appearance. Dual sets of gold-plated binding posts provide a secure connection and offer a choice of single-ended or bi-wire/bi-amplified connections.
