Altec 1505B (c. 1976–1977)

The 1505B is one of the big multi-cell horns Altec built for the Voice of the Theatre systems. It spent its life bolted on top of a bass cabinet in a theater or auditorium, not sitting in anyone's living room. As Audio (October 1985, p.362) noted in its classifieds, demand for high-end used Altec gear remained strong well into the 1980s. It's one of six models in Altec's Multi-Cell Horn Series, and like its siblings it was designed so a system designer could pick a horn by coverage pattern instead of guessing. Its rated pattern is 60° vertical by 105° horizontal, with a 500 Hz low-frequency limit. Altec's 1976 literature lists it as a 3×5 multicell - 15 cells in total - measuring 16¾"W × 30½"H × 18½"D (43 × 78 × 47 cm) and weighing 22 lbs (10.0 kg).

The throat is what makes the 1505B more flexible than a fixed horn. Swap in the 30166 throat and it runs a single driver. Fit the 30172 and it runs two. That is why the 1505B turns up in so many Voice of the Theatre configurations - the A2, A4, and A4X all list it as an option in Altec's own system tables - and why it's still a common sight in horn projects today, usually paired with 288 or 291 compression drivers.

Documentation on the 1505B specifically is thinner than you'd expect for a component this widely used. There's no surviving frequency response curve, no impedance or sensitivity figure, and no power handling spec that we've been able to verify. A 24,000-seat auditorium used it as part of its original installed system, and the design's reputation for wide, even coverage has kept it in circulation long after Altec stopped building it. Markus Klug of Klughoerner later produced a hand-crafted wood replica for enthusiasts who couldn't find originals. On the used market, completed sales over the past few months have ranged from about $19 for a rough single unit to $2,700 for a clean pair, with a median around $225.