JBL 2308

Name: JBL 2308
Brand: JBL

A slant plate acoustic lens built for precision dispersion. It weighs 0.5kg, about as much as a paperback, and it shapes the sound of JBL's pro-grade horn systems.

Overview

The JBL 2308 isn't an amplifier, speaker, or crossover. It's a lens. Specifically, it's a 25.4 cm slant plate type acoustic lens that refines how sound exits a horn assembly. It measures just 254 mm wide and 63 mm deep. It controls dispersion in short-distance applications when paired with JBL's 2307 or 2311 horns.

This is not a consumer-facing product. It emerged from JBL’s professional audio lineage, where precision and repeatability mattered more than aesthetics or ease of use. The 2308’s directional characteristics are rated at 80° horizontal by 45° vertical, measured with the 2307 and 2311 horns attached, suggesting a tightly controlled vertical dispersion pattern ideal for minimizing ceiling and floor reflections. While small and unassuming, its geometry plays a critical role in ensuring high-frequency energy is directed where it’s needed—toward the audience, not scattered.

Specifications

Manufacturer	JBL
Type	Lens
External dimensions	Width 254x Height 156x Depth 63 mm
Weight	0.5kg
Directional	80 ° x45 ° (measured with 2307, 2311 horns attached)
Description	25.4 cm slant plate type acoustic lens.
Throat exit	2
Frequency Response	500Hz~20kHz ±3db

Key Features

Slant Plate Geometry for Controlled Dispersion

The 2308 uses a slanted plate design. It refracts high-frequency output from the compression driver and horn throat to give a consistent 80° x 45° dispersion pattern. This helps keep coverage uniform across an audience plane, reducing hot spots and comb filtering. Later waveguides integrate into the horn body. The 2308 is an add-on component, so system designers can switch it or remove it depending on venue acoustics. The 25.4 cm measurement refers to the effective aperture size, which lines up with the throat dimensions of the 2307 and 2311 horns.

Velcro Tape Mounting System

There are no screws or clamps. The 2308 uses attached Velcro tape to secure the baffle plate to the horn assembly. That fits its intended use in touring and installed sound, where fast setup and teardown were priorities.

Two-Throat Exit Design

The "throat exit 2" specification indicates the lens interfaces with a dual-throat horn configuration, likely allowing symmetrical loading of the compression driver or bi-radial dispersion control. This matters when it's used with the 2307 or 2311 horns, which may use dual-path acoustic channels to improve high-frequency coherence.

Historical Context

The 2308 was priced at ¥10,000 around 1978 and ¥14,000 by 1983. It was a specialized component, not a standalone product, and it was sold as a single unit, as a system upgrade or replacement part. It was part of the JBL 2391 assembly, which comprises the 2307 horn and 2308 lens, in JBL's professional loudspeaker lineup of the late 1970s and early 1980s. No official production years are documented, but the pricing history lines up with JBL's broader horn development timeline for that period. It was marketed not to consumers but to sound contractors, studios, and touring companies who wanted predictable dispersion.

Collectibility & Value

The 2308 has picked up a following among vintage JBL enthusiasts and DIY audio builders. Used units reportedly sold for around $300 on eBay a few years ago, though current availability is sparse. Because originals are scarce, reproductions have appeared: KENRICK SOUND offers brand new replicas, and 3D-printed replacements show up on eBay, often labeled "3D Replacement." The original construction reportedly used glued blades, a potential point of failure after decades, while the reproductions advertise one-piece builds for better durability. Hifi Shark tracks used sales prices.