JBL 2360A Bi-Radial Horn (Early 1980s)

The JBL 2360A is a large-format Bi-Radial constant-directivity horn, built for 2" throat compression drivers like the 2445 or 2446. It was the high-frequency section of JBL's 4670 series studio monitors from the early 1980s. The 4670-1 paired it with a 15" 2235H woofer, and the 4671-1 used a 12" 2203H. This is professional monitoring hardware, not a consumer speaker. The horn alone weighs 31 kg (68 lb) and measures roughly 609 mm square by 530 mm deep.

The design is diffraction-based. JBL's Bi-Radial geometry keeps coverage consistent across the bandwidth. JBL's spec archive lists the usable range as 500 Hz to 16 kHz, with a nominal 90° x 45° dispersion pattern and a directivity index of 10 dB. In the 4670 system, the passive crossover sat at 1.2 kHz. Audio researcher James D. Johnston used a pair in his personal 5.1-channel home theater and crossed his over at 1 kHz with an active network. The horn can be rotated 90°, and Johnston mounted his with the 90° axis vertical to widen the horizontal pattern for home theater duty.

The 2360A saw real deployment in professional sound. Sound & Communication (November 1988, p.52) reported on an installation at the Stepan Center that used five 2360A horns with 2445J compression drivers. The horn also appeared on Lucasfilm's approved THX equipment list as of May 1989, per Audio (September 1989, p.71).

These are big pieces. A horn like this needs a substantial stand and a room with ceiling height to spare. One forum user put it this way: "they are big horns, brilliant though."

No original price, production years, or standalone sensitivity figures have surfaced in the documentation reviewed. Sources disagree on one point. Most cite 45° vertical dispersion, but at least one forum post claims 40°. JBL's own spec sheet says 45°, so that is the figure to trust.