Altec 515 (1966–1979)

At 11.8 kilograms and with a 389mm face, this is a driver built for authority, not subtlety.

Overview

The Altec 515 isn’t a single speaker but a lineage of high-output, horn-optimized 15-inch low-frequency drivers that evolved over decades. While often referred to generically as the “Altec 515,” the model exists in distinct iterations—most notably the 515B, released in 1966, and the 515C, introduced in 1979—each reflecting incremental refinements in power handling and construction. These are not bookshelf components or passive radiators for compact enclosures; they are industrial-grade units engineered for deep, controlled bass in large horn systems. Owners report the 515B and 515C as the most powerful 15-inch cone woofers in Altec’s lineup at their respective times, built to withstand serious thermal and mechanical stress while maintaining linearity under high excitation.

Despite the shared naming convention, the 515 designation spans vastly different eras and engineering philosophies. A Facebook post from a long-time collector claims the 1949 Altec 515 is “the most musical low-frequency speaker ever made,” though no technical data exists for that early version in the verified records. What is clear is that by the mid-1960s, Altec had standardized the 515B as a 38 cm (15-inch) cone woofer with a massive 76mm voice coil, 16 Ω impedance, and a frequency range stretching from a remarkably low 20 Hz up to 1 kHz. The later 515C retained the same core dimensions and frequency envelope but increased allowable input from 50W to 75W, suggesting improvements in thermal management or suspension durability. Both models were designed explicitly for horn loading, not free-air or sealed-box applications, and were commonly paired with Altec’s 288, 290, or 802 high-frequency drivers on 500 Hz crossover horns, as documented in the 1957 catalog.

Specifications

Manufacturer	Altec Lansing
Type	38 cm cone woofer unit
Frequency characteristic	20 Hz to 1 kHz
Lowest resonance frequency	25Hz
Impedance	16 Ω
Rated input	35W
Allowable input	50W (515B)
Allowable input	75W (515C)
Output sound pressure level	105dB/W/m (515B)
Output sound pressure level	104 dB (New JIS) (515C)
Magnetic flux density	14,750gauss
Recommended crossover frequency	500Hz
Voice Coil Diameter	76mm
External dimensions	Diameter 389x Depth 197 mm (515B)
Weight	11.8kg (515B)
Weight	12.4kg (515C)

Key Features

Alnico V Magnetic Circuit with 14,750 Gauss Flux Density

The Altec 515’s magnetic system is a standout feature—built around an Alnico V magnet, it generates a robust 14,750 gauss of magnetic flux density. This high field strength ensures strong motor control over the voice coil, translating to tighter bass response and improved transient accuracy. Unlike ferrite or modern neodymium designs, Alnico magnets are prized for their smooth saturation characteristics, which some engineers argue contribute to a more natural decay of low-frequency energy. The magnetic circuit itself is explicitly designed for horn loading, meaning it prioritizes efficiency and control at high sound pressure levels rather than maximum excursion in open-air environments.

76mm Voice Coil for High Power Handling

With a voice coil diameter of 76mm—exceptionally large for a 15-inch driver of its era—the 515 was engineered to dissipate heat efficiently and maintain stability under prolonged high-power input. The 515B’s 50W allowable input and the 515C’s 75W rating reflect this thermal resilience. Combined with a rated input of 35W across variants, the driver was clearly intended for professional or high-end domestic systems where sustained output mattered. The large coil also contributes to higher inductance, which may slightly roll off the upper end of its 1 kHz upper limit, but this is mitigated by the recommended 500 Hz crossover point.

38 cm Cone with 25Hz Resonance for Deep Bass Extension

Capable of reproducing frequencies down to 20 Hz with a free-air resonance of 25Hz, the 515 achieves genuine sub-bass performance—rare for cone drivers of its time. This low resonance is made possible by a compliant suspension and high moving mass, both optimized for use in horn-loaded cabinets like the 825B (A7), where the horn’s loading effect further extends low-end response. The 389mm external diameter places it firmly in the 15-inch category, though some variants, such as the 515-G series, list a 16-inch diameter (406mm), suggesting dimensional tolerances or different mounting configurations. The 515-G series also lists a depth of 6-1/16 inches (155mm) and a weight of 30 pounds (13.6kg), slightly heavier than the 515B and 515C, possibly due to a larger magnet or reinforced basket.

Historical Context

The Altec 515 emerged from a lineage of professional-grade loudspeakers developed for theater, broadcast, and high-fidelity reproduction. Its presence in the 1957 Altec catalog as a component in speaker systems—paired with high-frequency drivers on 500 Hz horns—confirms its role in full-range, high-efficiency designs. It was not a standalone consumer product but a modular unit for system builders. By 1966, the 515B represented the peak of Altec’s 15-inch cone woofer technology, billed as the most powerful in the company’s lineup. The 1979 release of the 515C suggests a continued demand for high-output, horn-compatible drivers even as solid-state amplification and new enclosure designs began to dominate the market. Despite the lack of published Thiele-Small parameters—common for Altec drivers of this era—the 515 series remains a benchmark for vintage horn system builders.

Collectibility & Value

While no official collectibility data exists in the fact sheet, market listings indicate strong demand for early Altec 515 units. A matched pair of 1940s Altec Lansing 515s in “Red/White/Blue” trim was listed for sale on Reverb, and individual units from 1953 have been offered at €2,000 and $2,299. These prices reflect rarity, provenance, and the cult status of vintage Altec drivers among high-end audio enthusiasts. Owners report that the GPA/Altec 515 is considered “the ultimate woofer” when used outside standard VOTT cabinets, with one user describing a system using ten 515s per side as a “real killer” for deep bass. Another claims a system with a GPA Altec 515-8C “will crush any of the current ‘high-end’ speakers I’ve heard anywhere near the price.” However, no data on common failures, maintenance issues, or long-term reliability is available, and original pricing documentation remains absent.