Altec Lansing 604-8H (1978)

Name: Altec Lansing 604-8H
Brand: Altec Lansing

At 17.2kg and 16 inches wide, this coaxial brute delivers studio-grade sound with a single-point source magic that still turns heads.

Overview

The Altec Lansing 604-8H emerged in 1978 as a high-performance speaker unit built for critical listening and professional monitoring. Part of the long-running 604 series, it represents —where the high-frequency driver sits concentrically within the woofer, creating a single apparent sound source. This configuration minimizes phase interference and time alignment issues between drivers, a key concern in studio environments where accuracy matters. The 604-8H wasn’t sold as a finished cabinet; it was a raw driver assembly intended for integration into custom enclosures, Its presence in the Great Plains Acoustics catalog as late as 2004 suggests enduring demand, and the fact that Great Plains Audio continues producing updated versions like the 604-8H-III today speaks volumes about its reputation.

Despite its age, the 604-8H was engineered with advanced features for its time. It uses a 38 cm (15-inch) cone woofer paired with a high-frequency horn driver—specifically Altec’s Mantaray Horn)—mounted via a coaxial arrangement. The Tangerine radial phase plug at the center of the high-frequency section helps manage dispersion, aiming to maintain a consistent pattern across frequencies. This is not a speaker built for stealth or decor; it’s a tool, heavy at 17.2kg, with a front baffle diameter of 16 inches and a depth of 11 inches. It demands space, both physically and acoustically.

Specifications

Type	2-way coaxial speaker unit
Woofer size	38 cm (15-inch) cone type
High-frequency driver	Horn Type (Mantarey)
Frequency response	20 Hz to 20 kHz
Lowest resonance frequency	30Hz
Impedance	8 Ω
Allowable input	65W
Output sound pressure level	103dB/W/m (New JIS)
Voice Coil Diameter (Low)	76 mm
Voice Coil Diameter (High)	45 mm
Crossover frequency	1.5kHz
Weight	17.2kg
Unit dimensions	16" diameter x 11" deep

Key Features

Mantaray Horn High-Frequency Driver

The 604-8H uses Altec’s proprietary Mantaray Horn), a design known for controlled dispersion and smooth high-frequency response. Unlike simple exponential horns, the Mantaray profile is engineered to minimize diffraction and breakup modes, delivering a more coherent wavefront. This horn, combined with the coaxial layout, ensures that high frequencies project from the same point as the lows, preserving spatial cues and imaging precision—critical in studio monitoring where panning and depth perception must be accurate. The 45 mm voice coil allows for high power handling and thermal stability, supporting the 65W allowable input rating.

Tangerine Radial Phase Plug

At the heart of the high-frequency section sits the Tangerine radial phase plug, a signature Altec innovation. More importantly, it helps maintain uniform dispersion by preventing sound waves from interfering destructively at the driver’s exit.

38 cm Coaxial Woofer with 76 mm Voice Coil

The low-frequency driver is a massive 38 cm (15-inch) cone unit cone type) with a 76 mm voice coil, a substantial size for the era. This large coil contributes to high power handling and excellent thermal control, allowing the speaker to sustain high output levels without compression. The woofer operates down to a lowest resonance frequency of 30Hz, and with proper enclosure design, can reach the full 20 Hz lower limit of its rated frequency response. The 8 Ω impedance makes it compatible with most professional and high-end consumer amplifiers of the time, though its 103dB/W/m sensitivity)) means it can be driven efficiently even by moderate-powered tube amps.

1.5 kHz Crossover Integration

The internal crossover network routes signals at 1.5 kHz, This ensures the horn handles only the upper midrange and treble, relieving it of the strain of reproducing lower mids where distortion and beaming are more likely. The crossover is passive and integrated into the unit, simplifying installation for builders. However, its fixed nature means system tuning is largely dependent on the enclosure design and placement.

Collectibility & Value

The Altec Lansing 604-8H commands serious attention in the vintage audio market. A single used unit in “Excellent” condition listed on Reverb sold for $999, reflecting strong demand among restorers and studio enthusiasts. While no original pricing data exists, the current secondary market suggests these are no longer disposable relics but sought-after components. One common issue reported by owners is the appearance of a “distinct white/off-white residue on the speaker’s surround”, likely due to aging of the flexible ring material over time. This can affect both aesthetics and performance if the surround becomes brittle. The continued production of updated versions by Great Plains Audio indicates that the 604-8H’s design remains relevant, and spare parts or modern equivalents may be available for restoration projects.