Altec 311-90 Horn

At 32 pounds, it carries the weight of a serious mid/high horn—one that still commands over $1,600 on the used market.

Overview

The Altec 311-90 horn isn’t a subtle piece of gear. It’s a mid/high frequency multicellular horn, built with robust construction and designed to project with authority. Owners report it as a centerpiece in high-efficiency systems, often mated with drivers like the 288-8G, 290E, or 291-16B, and referenced in builds ranging from jazz listening bars to hybrid setups with Khorns. While its exact origins remain undocumented, its presence in modern vintage audio circles is unmistakable—showing up in forums, Instagram posts, and high-end resale listings. It was reportedly used in applications described as "Voice of the Theater sound," suggesting a lineage tied to professional or high-fidelity public address environments.

Despite the lack of official production dates or original pricing, the 311-90 has developed a reputation for imaging clarity, particularly when paired with the 288 driver—a combination one listener called “the best imaging horn I heard.” Its physical presence is defined by dimensions labeled A: 53.5 cm, B: 32.6 cm, and C: 72.5 cm, forming a substantial multicellular mouth that dominates any cabinet it's mounted on. Collectors note its 90-degree dispersion and a flare rate of 300 Hz, though these values come from a single forum source and are not officially documented in manufacturer literature.

Specifications

Key Features

Multicellular Horn Design

The 311-90 employs a multicellular horn structure, a design choice that helps control dispersion and reduce high-frequency diffraction. This layout divides the horn mouth into multiple cells, each contributing to a more uniform wavefront and tighter beam control. While the exact acoustic engineering behind the cell pattern isn’t documented, the result is a horn capable of precise imaging—especially noted in listening environments where clarity and localization matter.

90 Degree Dispersion Pattern

Reportedly offering a 90-degree dispersion, the 311-90 strikes a balance between focused projection and room coverage. This horizontal spread makes it suitable for wide but controlled listening areas, avoiding the extreme narrowness of some theater horns while still minimizing ceiling and floor reflections. The dispersion figure comes from a single forum source, so it should be treated as observational rather than factory-certified.

Flare Rate of 300 Hz

According to available documentation, the horn has a flare rate of 300 Hz. This suggests the horn begins loading the driver in the lower midrange, aligning with crossover points around 300 Hz as seen in user setups. One system description notes a 300 Hz crossover with 12 dB/octave slope, implying the 311-90 is intended to take over from a woofer in that region, reinforcing its role as a mid/high unit rather than a pure tweeter horn.

Frequency Range: 500–3000 Hz

The documented frequency range spans 500 Hz to 3000 Hz, indicating the horn is optimized for midrange and lower treble. This range complements drivers like the 288 and 290 series, which are known for smooth, extended response in this band. The upper limit at 3 kHz suggests it may be used with a separate high-frequency horn or tweeter in full-range systems, particularly in multi-way professional or high-fidelity configurations.

Robust Construction and Weight

Weighing in at 32 pounds (14.5 kg), the 311-90 is a physically substantial unit. Its robust construction implies durability for both studio and live sound use, though no official details on materials are provided. The weight likely comes from thick walls and dense internal structures needed to prevent resonance in a high-output horn. Surviving units often require maintenance due to age, according to collectors, which may include bracing repairs or driver mount refurbishment.

Collectibility & Value

The Altec 311-90 has become a sought-after item among vintage horn enthusiasts. A used price of $145 was listed in July 1994, but current market value reflects a dramatic increase. Recent listings show pairs selling for JPY 163,636 (approximately $1,100 at the time) and individual units priced at $1,699.95 plus shipping on Reverb. It also appears regularly on eBay, often in high-end audio resale circles. Due to their age, surviving units frequently require maintenance, and spare parts availability is undocumented.

eBay Listings

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