Altec 515B / 515-8G Woofer
The Altec 515 series is the most powerful line of 15-inch cone woofers in Altec's lineup. It was designed for horn-loaded use in the Voice of the Theatre systems. The 515B and its successor, the 515-8G, delivered high efficiency and deep bass in the front-loaded A7 cabinet.
Specifications
| Type | 15" (380mm) Low-Frequency Loudspeaker |
|---|---|
| Voice Coil Diameter | 3 inches (76mm) |
| Magnet | Alnico V |
| Nominal Impedance | 8 Ω (515-8G) / 16 Ω (515B) |
| Power Handling | 50W continuous, 100W program |
| Frequency Response | 20 Hz - 1,000 Hz |
| Sensitivity | ~100 dB/W/m (in horn-loaded cabinet) |
| Recommended Crossover | 800 Hz (with 288 or 291 compression drivers) |
Design Overview
The 515 series was engineered for horn-loaded cinema work. Direct-radiating woofers are built for sealed or vented boxes. The 515 was optimized for front-loaded horn operation in the A7 and similar cabinets.
Key design characteristics:
- Horn-Load Optimized: Magnetic circuit and suspension designed for front-loaded horn operation
- High Efficiency: Capable of 100+ dB sensitivity when properly horn-loaded
- Extended Bass: Reaches down to 20 Hz in A7 cabinet for full-range cinema sound
- Alnico V Magnet: Provides stable, high-flux magnetic field
- Large Voice Coil: 3-inch diameter for excellent power handling
Applications
The 515 series was the foundation of Altec's cinema and professional systems:
- Voice of the Theatre A7 - Primary woofer in the legendary cinema speaker
- Voice of the Theatre A5 - Mid-sized cinema system
- 825B Cabinet - Front-loaded enclosure for the 515
- Professional sound reinforcement systems
In the Wild
Featured in Resistor Magazine's restoration profile of Iwan Arjanto's vintage speaker collection. The 515 woofer, in its various iterations, is the low-frequency foundation of the Altec A7 speakers. Arjanto has built four pairs of them for customers.
When restoring or building A7 systems, Arjanto tests each driver carefully before installation. The 515 is built tough, and even decades-old examples can often be returned to full performance with minimal service.
Evolution: 515B to 515-8G
The 515 was refined throughout its production life:
- 515B: Early version, typically 16 ohms
- 515-8G: Later version with improved suspension and 8-ohm impedance
- 515-16G: Later version maintaining 16-ohm impedance
- 515-8GHP: High-power variant
The "G" series got refinements to the cone and suspension materials. The magnetic structure and the performance characteristics stayed the same.
Operational Notes
The 515 is designed for horn-loaded operation:
- Intended for front-loaded horn cabinets (like the A7)
- Not suitable for direct-radiator sealed or vented boxes
- Typically crossed over at 800 Hz to Altec 288 or 291 compression drivers
- Requires N-500 series crossover network for proper operation
Related Drivers
- Altec 416 - Similar 15" driver optimized for direct-radiator applications
- Altec 414 - 12" version for smaller VOTT systems (A4)
- JBL 2235H - Contemporary high-performance 15" woofer
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Related Models
- Altec 1803B
- Altec 23746 (1975)
- Altec 26421 (1975)
- Altec 288-16G
- Altec 288-8H/16H
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- Braun AUDIO-250 (1965)
- Magnavox Component Systems (1972)
- Acoustic Research AR (1967-1976)
- Acoustic Research 11