JBL 2356 Bi-Radial Horn
The JBL 2356 is a large-format Bi-Radial® horn with a 2-inch throat, built for professional sound reinforcement and cinema use. It is the fiberglass version of the cast-aluminum JBL 2360A. Same design, same intended drivers, but molded in one-piece fiberglass-reinforced polyester instead of cast metal. That made it lighter and cheaper to produce. Today it makes the 2356 a relative bargain on the used market compared to its aluminum sibling.
The horn has 90° x 50° nominal dispersion. That is the hallmark of JBL's Bi-Radial design, which combines horizontal and vertical curved surfaces to hold constant directivity across the frequency range. It was intended for JBL's large-format compression drivers. The 2445, 2446, 2450, and 2451 are commonly cited, though an official compatibility list hasn't been confirmed in the surviving documentation.
Owner reports are generally enthusiastic. They describe excellent imaging and a smooth, natural midrange when the horn is paired with appropriate drivers. The common caveat is that fiberglass can ring. Several users note a resonance in the upper mids at high SPL, and some have added external damping material to tame it. Some owners also report vibration you can feel at the horn throat when it's pushed hard. One AudioKarma user called the 2356 "a sleeper - same sound as the 2360A for half the money." Period coverage of JBL professional products in the late 1970s documents their use in large-scale sound reinforcement installations, including cinema systems Sound and Communication (September 1988, p.58).
Surviving documentation is thin. No official datasheet, exact production years, or original list price have surfaced in the archives. What is well-established is the relationship to the 2360A and the material difference between them. The 2356 shows up regularly on eBay, typically selling in the $200 - $400 range per horn depending on condition. Things to look for: fiberglass cracks or chips at the mounting flange, finish wear, and corroded mounting hardware.
- Type: Bi-Radial® horn, large format
- Throat: 2-inch
- Dispersion: 90° x 50° nominal
- Material: Fiberglass (fiberglass-reinforced polyester)
- Relation: Fiberglass version of the cast-aluminum 2360A
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