University Sound Cobreflex III
A folded sectoral PA horn that packs a hundred degrees of horizontal coverage into seven pounds of glass-reinforced polyester.
Overview
The Cobreflex III is a folded sectoral, wide-angle horn built by University Sound for public address, paging, and voice warning systems — the kind of job where intelligibility across a wide room matters more than musical finesse. The design brief is written right into the geometry: 100° of horizontal beamwidth and 60° of vertical beamwidth at 2.0 kHz, a pattern wide enough to cover a hall from a single mounting point. The horizontal figure is confirmed in the manufacturer's own specifications and in the architects' and engineers' copy, and the beamwidth-versus-frequency plots back it up.
What makes the Cobreflex III interesting mechanically is the fold. University's patented design (patent #4,176,731) puts two separate air columns inside a single assembly, which the documentation credits with virtually eliminating the high-frequency phase cancellation that plagues re-entrant designs. That's the whole point of the "reflex" label — it's not marketing fluff, it's a real acoustic distinction. The folded construction also buys compactness without giving up efficiency, provided the horn is paired with the appropriate University Sound compression drivers. A threaded metal throat insert accepts a screw-in driver with a throat opening between 0.7 and 1.0 inch on a standard 1⅜-inch thread, and the recommended driver listed in the manual is the ID30C-8.
Coverage is only useful if the horn actually loads down low, and here the numbers are respectable for the format: useful acoustic loading is maintained to a low-frequency cutoff of 250 Hz. That's not subwoofer territory, obviously — this is a speech-and-signal horn — but 250 Hz is low enough to keep voices from sounding thin and pinched. The axial directivity factor comes in at 15.9 at 2.0 kHz, a figure University derived from horizontal and vertical polar measurements taken in their large anechoic chamber. Those polar runs used one-third-octave pseudorandom pink noise, with the measurement microphone placed 6.1 m (20 ft) from the horn mouth and rotation about the waveguide's geometric apexes — close enough to the acoustic apexes across the measured range that the resulting error is described as inconsequential. The horn was suspended freely with no baffle during testing, so the published polars reflect the device itself rather than a cabinet.
The physical package is where the Cobreflex III earns its keep on a ladder. It measures 36.8 cm (14.5 in) high, 69.2 cm (27.5 in) wide, and 38.1 cm (15.0 in) deep, and weighs 3.2 kg (7.0 lb) net. That's a horn you can hang and aim without a rigging crew, and the serrated positive-lock "U" mounting bracket — affixed to the bell by self-locking nuts — provides orientation adjustment in all three planes. Anyone who has fought a fixed-angle PA horn will recognize how much that flexibility is worth on install day. The bell itself is molded from non-resonant glass fibre reinforced polyester with a self-colored gray finish, and a painted steel U-bracket rounds out the hardware. The material choice matters: a horn this size ringing like a bell would smear everything it reproduces, and the glass-reinforced polyester is specifically there to keep that from happening.
There's a documentation curiosity worth flagging for anyone comparing spec sheets. Some of University's own literature describes the horn body as high-impact ABS finished in ultraviolet-inhibiting gray paint, and gives smaller dimensions — 23.5 cm high, 47.0 cm wide, 26.0 cm deep, weighing no more than 2.3 kg — along with an 80° horizontal beamwidth at 2 kHz. That passage identifies the horn as the Cobreflex IIB, a different model in the same family, so those figures should not be applied to the III. The Cobreflex III's own specification pages consistently give the 100° × 60° pattern, the 250 Hz cutoff, the 3.2 kg weight, and the glass fibre reinforced polyester construction described above.
University Sound backed the speaker products with a limited five-year warranty from the date of original purchase, covering malfunction due to defects in workmanship and materials — repair or replacement at the company's option, with the unit shipped prepaid to the factory and returned prepaid. The exclusions are the usual ones: finish and appearance items, burned coils, and damage from abuse or operation outside specified conditions, including cone or coil damage from improperly designed enclosures. Repair by anyone other than University Sound voided the guarantee. For service, the documentation routes paging speakers and speaker products to University Sound's Oklahoma City address, while a separate list of product lines — LR Line radiators, PI Series, Musicaster100, Interface Series, and others — goes to Buchanan, Michigan. The Cobreflex III falls under the paging speaker category.
None of this is glamorous gear. It's the horn you find bolted to a wall above a loading dock or a school gym, doing a job for decades with no one paying it much attention. But the engineering is honest: a patented fold that solves a real problem, a coverage pattern chosen for the task, and a mounting system that respects the installer. For anyone who collects PA and industrial audio, that's exactly the appeal.
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