[. . . ] S u b w o o f e r Choosing an Enclosure Loud + Clear subwoofers are optimized to perform best in small, sealed, vented and prefabricated bandpass enclosures. [. . . ] If you are using a small amplifier, a vented box will provide more bass output from less power. Because vented enclosures require the volume of the enclosure and the size of the port to have a specific relationship to the characteristics of the woofer, they must be built exactly to the specifications provided. While there are some prefabricated vented boxes available, matching a prefabricated box to a particular woofer is difficult. If you wish to use a vented enclosure, we strongly recommend having your authorized JBL dealer build it or at least verify that your design is correct if you wish to build it yourself. An optimum vented enclosure is always larger than the optimum sealed box for the same woofer, and will require more space inside the vehicle. Bandpass enclosures often provide the greatest output available from any amplifier/subwoofer combination, albeit at the expense of sonic accuracy. If sheer SPL (sound pressure level) is what you desire most, choose a bandpass enclosure. Because bandpass-enclosure design is tricky, using a computer and enclosure-design software is necessary. [. . . ] (28. 31 Liters) 4" (101. 6mm) 6" (152. 4mm) Sealed-Chamber Volume Vented-Chamber Volume Port Diameter Port Length JBL Consumer Products 250 Crossways Park Drive, Woodbury, NY 11797 1-800-336-4JBL (4525) (USA only) www. jbl. com © 2000 JBL, Incorporated JBL is a registered trademark of JBL, Incorporated. [. . . ]