Altec Voice of the Theatre A7
1947 - 1970s
The Voice of the Theatre A7 is arguably the most iconic cinema speaker ever created. Introduced in 1947, this massive two-way horn-loaded system defined the sound of movie theaters for decades and remains a coveted collector's item for high-efficiency audio enthusiasts.
Specifications
| Type | 2-way, combination horn/bass-reflex cinema loudspeaker |
|---|---|
| Low Frequency Driver | Altec 515B 15" woofer (later 515-8G) |
| High Frequency Driver | Altec 288 compression driver with 811B sectoral horn |
| Crossover Frequency | 800 Hz |
| Nominal Impedance | 8 Ω or 16 Ω |
| Power Handling | 50W continuous, 100W program |
| Sensitivity | 104 dB/W/m |
| Frequency Response | 40 Hz - 16 kHz |
| Dimensions | 42" W x 26" H x 24" D (with baffles) |
| Weight | Approximately 140 lbs per speaker |
Drivers Used
- Woofer: 515B or 515-8G - 15" high-efficiency woofer with Alnico V magnet
- Compression Driver: 288 series - 1.75" diaphragm compression driver
- Horn: 811B - 90° x 40° sectoral horn
Design Overview
The A7 is a combination horn and bass-reflex design. The 515 woofer is mounted in a large vented enclosure that provides extended bass response while maintaining high efficiency. The 288 compression driver on the 811B horn provides wide coverage and excellent intelligibility for dialog.
Early A7 models featured side wings or baffles that helped control dispersion and increase bass loading. Later "Voice of the Theatre" branded models were available without these side wings for home use.
Variants
- A7-500: Original version with 288 compression driver
- A7-500-8: 8-ohm version with updated components
- A7-500-8E: Later export version
- A7-8: Home version without side wings
Historical Context
The Voice of the Theatre series was developed to address the needs of the booming post-war cinema industry. The A7 quickly became the industry standard, installed in thousands of movie theaters worldwide. Its exceptional efficiency (over 100 dB sensitivity) meant it could fill large spaces with modest amplifier power.
Today, A7 speakers are prized by horn enthusiasts for their dynamic, uncompressed sound quality. Many have been restored for home use in large listening rooms or for vintage cinema installations.