User manual JBL P1220DII

[. . . ] 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. [. . . ] If you are using a small amplifier, a vented box will provide more 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. Bandpass 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 bandpass enclosure. Bandpass-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 enclosure described in the enclosure design sheet included with this woofer. Fortunately, there are many prefabricated bandpass boxes available and they are all optimized to extract the most output possible from any woofer. Bandpass enclosures can be quite large and may require a lot of space inside your vehicle. 02 Connecting Your Subwoofer to Your Amplifier JBL Power Series JBL Power Series subwoofers are available in two different configurations: as a single 2-ohm voice coil or as dual 2-ohm voice coils. Depending on the amplifiers you are using, you may use either single-voice coil or dual-voice coil subwoofers in singles or multiples to maximize the power available from your amplifiers. To achieve the maximum amplifier output possible, you should design a speaker system that provides the lowest impedance that your amplifier is rated to drive safely. When designing a subwoofer system, consider the following rules: 1. Don't mix different subwoofer or enclosure types in the same system (use all single-coil woofers or all dual-coil woofers). [. . . ] The total system impedance of voice coils (or woofers) in series = w1 + w2 + w3. . . The diagrams below and at right show parallel and series speaker connections. Figure 1. Parallel connection RED STRIPE POS ( + ) BLACK STRIPE NEG ( ­ ) Figure 2. [. . . ]