JBL Professional Enclosure Guide
The JBL Professional Enclosure Guide is a comprehensive reference document for building vented (bass-reflex) enclosures using JBL professional woofers and subwoofers. Originally published in 1998 and updated through 2003, this guide provides specific cabinet dimensions, tuning frequencies, and port specifications for a wide range of JBL drivers.
Document Information
| Title | JBL Professional Enclosure Guide |
|---|---|
| Original Date | September 17, 1998 |
| Last Modified | April 22, 2003 |
| Author | JBL Professional |
| File Size | 37 KB (PDF) |
What's Included
This guide covers:
- 13 enclosure designs ranging from 1.5 to 20 cubic feet
- Tuning frequencies from 30 Hz to 80 Hz for different applications
- Complete dimension tables with height, width, depth, and port specifications
- Cabinet building suggestions including materials, bracing, and construction techniques
- Vent placement guidelines for optimal performance
- Insulation recommendations using fiberglass or alternative materials
- Multi-woofer configurations for dual driver setups
- Bibliography of recommended audio reference books
Drivers Covered
The enclosure guide provides specific recommendations for the following JBL drivers:
Professional Woofers
- 128H - Hi-fi low-end or small subwoofer
- 2202/2202H - Midrange or guitar applications
- 2204/2204H - General purpose low-end or MI bass
- 2205/2205H - General purpose low-end
- 2206/2206H - General purpose low-end or MI bass
- 2215/LE15 - Hi-fi low-end or subwoofer
- 2220/2220H - Midrange, guitar, or full-range MI bass
- 2225/2225H - General purpose low-end
- 2226/2226H - General purpose low-end
- 2227/2227H - General purpose low-end
- 2234/2234H - Hi-fi low-end or subwoofer
- 2235/2235H - Hi-fi low-end or subwoofer
- 2241/2241H - Subwoofer
- 2242/2242H - Subwoofer
- 2245/2245H - Subwoofer
Professional Midrange
- 2118/2118H - Midrange (sealed sub-chamber required)
- 2123/2123H - Midrange (sealed sub-chamber required)
- LE5 Series - Midrange drivers
E Series (Musical Instrument)
- E110 - Midrange (sealed sub-chamber required)
- E120 - Midrange or guitar
- E130 - Full-range or MI bass
- E140 - General purpose low-end
- E145 - General purpose low-end
- E155 - Bass guitar (smallest box configuration)
G Series
- G125 - Midrange or guitar
- G135 - Full-range, MI bass, or general purpose low-end
Full-Range
- LE8T-H - Full range (flat response down to 30 Hz)
Key Enclosure Recommendations
| Chart # | Volume (cu ft) | Tuning (Hz) | Recommended For |
|---|---|---|---|
| 1 | 1.5 | 80 Hz | 2202, 2220, E120, G125 (midrange/guitar) |
| 2 | 2.0 | 40 Hz | 2204, 2206 (general purpose low-end) |
| 3 | 2.5 | 30 Hz | 128H (hi-fi low-end/small sub) |
| 4 | 3.0 | 40 Hz | 2220, E130, G135 (full-range/MI bass) |
| 5 | 3.4 | 32 Hz | LE8T-H (full range) |
| 6 | 4.0 | 40 Hz | 2205, 2225, 2226, 2227, E140, E145, G135 |
| 7 | 4.0 | 40 Hz | Double 2204, 2206 |
| 8 | 5.0 | 30 Hz | General purpose low-end |
| 9 | 6.0 | 40 Hz | 2234, 2235, 2215/LE15 (hi-fi/sub) |
| 10 | 8.0 | 40 Hz | E155 (smallest box for bass guitar) |
| 11 | 10.0 | 30 Hz | Double 2225, 2205, 2226, E145, E140, G135 |
| 12 | 20.0 | 30 Hz | Double 2245 (subwoofer) |
| 13 | 10.0 | 40 Hz | 2241, 2242 (subwoofer) |
Construction Highlights
Materials
The guide recommends dense, void-free "marine-grade" plywood, Finnish or Baltic birch (19mm/3/4" or thicker) for transported enclosures. High-density fiber or particle board can be used for permanent installations.
Bracing
Bracing should make the cabinet as rigid and resonance-free as possible. Use 2x4s or 75mm (3-inch) birch ply pieces, placed at slightly odd intervals:
- One brace for panels 300-600mm (12-24")
- Two braces for panels 500-1200mm (18-36")
- Three braces for larger panels
Midrange Chambers
Models 2118, 2123, and E110 used for midrange require a small sealed sub-chamber of approximately 0.4 cubic feet (7 liters / 0.25 cu ft) net internal volume. The guide suggests using a tube filled with a "jelly roll" of fiberglass or a non-uniform box lined with fiberglass.
Important Warnings
Do Not Expect 20 Hz From a 40 Hz Box
Bass-reflex systems should not be operated below their tuned frequency. Attempting to operate the cabinet below the tuned frequency can damage woofers. The use of a high-pass filter (such as in the JBL 5235 Electronic Frequency Dividing Network) is highly recommended with vented loudspeaker systems to prevent sub-sonic signals from causing hazardously long cone excursion.
Download
Download JBL Professional Enclosure Guide (PDF, 37 KB)
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See Also
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