Altec 804A

At 19 pounds, it’s heavier than most guitar amps half its size—yet this hunk of cast metal and aluminum sings with a clarity that still startles decades later.

Overview

The Altec 804A is a high-frequency compression driver produced by Altec Lansing, a name that still carries weight in the world of vintage audio. Though overshadowed in reputation by its more celebrated sibling, the 802D, the 804A holds its own as a classic model built for precision in controlled environments. Designed for use in smaller spaces like home listening rooms or modest recording studios, it targets non-reverberant conditions with moderate ambient noise—essentially, the real-world spaces where most people actually listened to music. It’s not a stadium-filling beast, but a focused tool meant to deliver clean, articulate highs without overwhelming the room.

What surprises many first encountering the 804A is how much engineering is packed into a unit that, on paper, shares DNA with others in the Altec lineup. It uses a 1.75" aluminum ribbon edge-wound voice coil coupled to a 2.25" aluminum diaphragm with tangential compliance—a design choice that enhances linearity and reduces distortion at high frequencies. A mechanical phasing plug with two exponential acoustic slots ensures that sound waves from the center and outer edges of the diaphragm arrive in phase, a critical detail for coherent dispersion and time alignment. This isn’t guesswork; it’s deliberate acoustic architecture. The result is a driver capable of reaching up to 22,000 Hz, though real-world listening reports suggest a slight softening above 10 kHz, particularly when paired with certain crossovers like the N-800-F.

Despite its visual similarity to the 806A, the 804A is not identical—internally, it diverges significantly, though the exact nature of those differences isn’t fully detailed in available documentation. It shares core design principles with the 802D, but with a key distinction: the magnet. Where the 802D boasts a 1.2 lb., 15,250 Gauss magnet, the 804A uses a 13 oz., 13,000 Gauss unit. This reduction in magnetic strength affects efficiency and output capability, positioning the 804A as a more modest performer, better suited to lower-SPL environments. Still, in listening comparisons at moderate levels (around 80–95 dB SPL), the sonic differences between the two are reportedly minimal, suggesting that the core transduction technology remains highly effective.

In full-system applications—such as the “Stokowski” speakers built with Duelund CAST crossovers—the 804A contributes a musically natural, intensely beautiful presentation, praised for its stunning midrange and overall coherence. However, the same setups reveal its limitations: the top end is described as slightly soft, and while the bass is powerful, it doesn’t reach deep. This isn’t a flaw so much as a character trait—part of the Altec “sound” that enthusiasts either chase or correct with careful system matching.

Specifications

Key Features

1.75" Aluminum Ribbon Edge-Wound Voice Coil with Tangential Compliance

The 804A employs a 1.75" aluminum ribbon edge-wound voice coil, a design that improves heat dissipation and reduces mass compared to traditional round-wire coils. Paired with a 2.25" aluminum diaphragm featuring tangential compliance, this setup allows for greater linearity in high-frequency reproduction. The compliance design helps decouple mechanical stresses, reducing distortion and enabling smoother response across the driver’s operating range.

Mechanical Phasing Plug with Exponential Acoustic Slots

A precisely engineered phasing plug sits at the heart of the driver, incorporating two exponential acoustic slots. These slots manage the phase relationship between sound waves generated at the center and outer edges of the diaphragm, ensuring time-coherent output. This feature is critical for maintaining clarity and directivity, especially when the driver is coupled to a horn.

13 oz., 13,000 Gauss Magnet Assembly

The 804A is equipped with a 13 oz. magnet producing 13,000 Gauss, a step down from the 802D’s 1.2 lb., 15,250 Gauss unit. This difference defines the 804A’s position in the lineup—less output, lower efficiency, but still sufficient for domestic and studio monitoring applications. The gap flux is reportedly around 12,000 gauss, indicating strong magnetic coupling in the voice coil gap.

Internal Design Differences from 806A

Though the 804A and 806A appear identical externally, they are not the same driver. Documentation confirms internal differences, though specifics are not detailed. This distinction matters for restoration and replacement—owners cannot assume interchangeability based on外形 alone.

Shared Core Design with 802D

The 804A and 802D are fundamentally the same compression driver design, differing primarily in magnet size and strength. This shared architecture explains why listening tests reveal minimal sonic differences at moderate levels. The 804A can be seen as a cost- or application-optimized variant of the 802D, tailored for environments where extreme output isn’t required.

Historical Context

The Altec 804A was engineered for use in non-reverberant spaces with moderate ambient noise, conditions typical of average home listening rooms or smaller broadcast and recording studios. It was not intended for large venues or high-noise environments, but rather for critical listening where clarity and accuracy mattered more than raw volume. This focus on controlled acoustics reflects a shift in professional and high-fidelity audio during its era—toward dedicated listening spaces and calibrated monitoring.

Collectibility & Value

While the vintage Altec 802D enjoys legendary status, the 804A remains less discussed, despite being a classic model in Altec’s own classification. A used unit was once listed for $249 in "Near New Cond," and current market listings show similar drivers—sometimes mounted in horns like the H-811 B—priced around $325.00. Its appeal lies not just in performance but in its retro charm and build quality, making it a sought-after component for DIY speaker builders and vintage audio enthusiasts. However, no data exists on original pricing, production years, or common failure modes, leaving gaps in its full collector profile.

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