JBL 2301 Acoustic Lens
The JBL 2301 is a perforated plate acoustic lens designed for high-frequency reproduction above 1200 Hz. Part of JBL's innovative acoustic lens family first introduced in 1954, the 2301 uses a unique ring-shaped perforated barrier design to achieve a smooth, conical 90° dispersion pattern ideal for 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 JBL 2301 acoustic lens represents an innovative approach to high-frequency sound dispersion. Unlike conventional horns that rely solely on wall geometry, the 2301 uses a perforated plate design:
- 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
The JBL family of acoustical lenses was originally designed for stereophonic audio systems for motion picture theater applications, first presented to the industry in 1954. The acoustic lens concept, originally described by Bell Laboratory scientists Kock and Harvey in 1949, had not previously been applied to commercial sound reproduction. The JBL acoustic lens was the first real innovation in high-frequency sound reproduction since the early 1930s.
Applications
The 2301 is intended for use as 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
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