Altec 311-90 Horn

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

Overview

The Altec 311-90 horn isn't subtle. It's a mid/high frequency multicellular horn, built heavy and designed to project. 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. Its exact origins remain undocumented. It shows up in forums, Instagram posts, and high-end resale listings. It was reportedly used in applications described as "Voice of the Theater sound," which suggests a lineage tied to professional or high-fidelity public address environments.

There are no official production dates or original pricing, but the 311-90 has a reputation for imaging clarity, particularly when paired with the 288 driver. One listener called that combination "the best imaging horn I heard." The dimensions are labeled A: 53.5 cm, B: 32.6 cm, and C: 72.5 cm, which makes for a big multicellular mouth that dominates any cabinet it's mounted on. Collectors note a 90-degree dispersion and a flare rate of 300 Hz, though these values come from a single forum source and are not in any manufacturer literature.

Specifications

Key Features

Multicellular Horn Design

The 311-90 uses a multicellular horn structure. That layout divides the horn mouth into multiple cells, which helps control dispersion and reduce high-frequency diffraction. Each cell contributes to a more uniform wavefront and tighter beam control. The exact acoustic engineering behind the cell pattern isn't documented. The horn is noted for precise imaging, especially in listening environments where clarity and localization matter.

90 Degree Dispersion Pattern

The 311-90 is reportedly a 90-degree dispersion horn. That is a balance between focused projection and room coverage. The horizontal spread suits wide but controlled listening areas, avoids the extreme narrowness of some theater horns, and still minimizes ceiling and floor reflections. The dispersion figure comes from a single forum source, so treat it as observational, not factory-certified.

Flare Rate of 300 Hz

According to available documentation, the horn has a flare rate of 300 Hz. That suggests it begins loading the driver in the lower midrange, which lines up with crossover points around 300 Hz in user setups. One system description notes a 300 Hz crossover with a 12 dB/octave slope. That implies the 311-90 takes over from a woofer in that region, as a mid/high unit rather than a pure tweeter horn.

Frequency Range: 500–3000 Hz

The documented frequency range runs 500 Hz to 3000 Hz, so the horn is optimized for midrange and lower treble. That range suits 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

At 32 pounds (14.5 kg), the 311-90 is a physically substantial unit. Its heavy 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. According to collectors, surviving units often need maintenance due to age, which may include bracing repairs or driver mount refurbishment.

Collectibility & Value

The Altec 311-90 is sought after among vintage horn enthusiasts. A used price of $145 was listed in July 1994, but current market value is much higher. 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. Surviving units frequently need maintenance because of their age, and spare parts availability is undocumented.

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