JBL 2301 Acoustic Lens
The JBL 2301 is a perforated plate acoustic lens for high-frequency reproduction above 1200 Hz. It belongs to the JBL acoustic lens family, first introduced in 1954. The 2301 uses a ring-shaped perforated barrier to get a smooth, conical 90° dispersion pattern, which suits short-throw applications.
Specifications
| Type | Perforated Plate Acoustic Lens |
|---|---|
| Design | Ring-shaped perforated barriers with varying center cutouts |
| Coverage Pattern | 90° conical (constant in all planes) |
| Frequency Range | Above 1200 Hz |
| Sensitivity | 109 dB (1W/1m, 4V into 16Ω, warbled 1.2-2.5 kHz) |
| Throat Diameter | 25 mm (1 inch) - accepts 1" drivers only |
| Nominal Q | 4 (2 kHz octave band) |
| Maximum Throw | 9 m (30 ft) |
| Height | 146 mm (5¾ in) |
| Width | 173 mm (6⅞ in) |
| Weight | 1.6 kg (3.5 lb) |
Design Overview
The 2301 handles high-frequency dispersion differently from a conventional horn. A horn relies only on its wall geometry. The 2301 uses a perforated plate instead:
- Perforated Barriers: A collection of ring-shaped screens with varying sizes of center cutouts
- Hyperbolic Profile: The assembled plate openings describe a hyperbolic shape in all planes
- Lens Diffraction: Determined by both plate spacing and hole size in the screens
- Soft Edge Pattern: Well suited to high quality music reproduction
Historical Context
JBL originally designed its family of acoustical lenses for stereophonic audio systems in motion picture theaters, and first presented them to the industry in 1954. Bell Laboratory scientists Kock and Harvey described the acoustic lens concept in 1949, but nobody had applied it to commercial sound reproduction before. The JBL acoustic lens was the first real innovation in high-frequency sound reproduction since the early 1930s.
Applications
The 2301 is meant to be the high frequency element in:
- Two-frequency band integrated systems
- Three-frequency band integrated systems
- Short-throw reinforcement applications (up to 9m/30ft)
- High quality music reproduction systems
Compatible Drivers
The 2301 accepts 25 mm (1 inch) throat drivers only. Compatible JBL drivers include:
- JBL LE85 - 1" throat compression driver
- JBL 2425 - 1" throat compression driver with titanium diaphragm
- Other 1" throat compression drivers
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Documentation
- Lansing Heritage - Comprehensive JBL specifications, photos, and historical documents
- HiFi Engine - JBL manuals, service documents, and brochures
- Audio Karma JBL Forum - Community discussions and restoration guides