JBL GT5-12 manual Choosing AN Enclosure

CHOOSING AN ENCLOSURE

WARNING: Playing loud music in an automobile can permanently damage your hearing, as well as hinder your ability to hear traffic. We recommend listening at low levels while driving. JBL accepts no liability for hearing loss, bodily injury or property damage resulting from use or misuse of this product.

GT Series subwoofers are optimized to perform best in small, sealed, vented and prefabricated band-pass enclosures. While infinite-baffle mounting of GT Series subs is possi- ble, power handling will be greatly compromised because there’s no enclosed volume of air to prevent the speaker’s cone from moving past its limit. For this reason, we do not recommend infinite-baffle mounting for GT Series subwoofers.

You should choose the enclosure you will use based on the type of music you listen to, how much amplifier power you will use for the subwoofer and how much space inside the vehicle you can devote to a subwoofer enclosure.

Because a sealed enclosure provides the most control over the woofer’s movement, a woofer mounted in a sealed enclosure will handle more power than a woofer mounted in another enclosure type. Sealed enclosures provide more- accurate sonic reproduction than other enclosure types when mounted inside a vehicle, so they are well suited to all types of music. Sealed-enclosure construction is straightforward, and there are many

prefabricated sealed enclosures available. An optimum sealed enclosure is always smaller than other types of enclosures optimized for a particular speaker, so they require the smallest amount of space inside the vehicle.

Vented enclosures provide better efficiency in the 40Hz – 50Hz range, but this efficiency comes at the expense of sound in the lowest octave (below 40Hz) and at the expense of some control and power handling at the lowest frequencies. If you are using a small amplifier, a vented box will provide more perceived bass output from less power. Vented enclosures are also well suited to a variety of music types. Because vented enclosures require the volume of the enclosure and the size of the port to have

a specific relationship with the characteristics of the woofer, the enclosure 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 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.

Band-pass enclosures often provide the most output available from any amplifier and subwoofer combination, at the expense of sonic accuracy.

If sheer SPL (sound-pressure level) is what you desire most, choose a band-pass enclosure. Band-pass- enclosure design is very tricky, and the aid of a computer and enclosure design software is necessary. If you are an experienced installer or have some woodworking experience, you may wish to build the band-pass enclosure described in the enclosure design sheet included with this woofer. Fortunately, there are many prefabricated band-pass boxes available, and they are all optimized to extract the most output possible from any woofer. Band-pass enclosures can be quite large and may require a lot of space inside your vehicle.

2