User manual JBL 82T

[. . . ] GT4 Series subwoofers are optimized to perform best in small, sealed, vented and prefabricated bandpass enclosures. While infinitebaffle mounting of GT4 Series subs is possible, 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 GT4 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, 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. 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. We recommend that you avoid connecting separate woofers in series. The amplifier-damping factor (the amplifier's ability to control the motion of the woofer) is expressed as a ratio of terminal impedance (the sum of speaker impedance, wire resistance and the D. C. resistance of any crossover coil connected to the woofer) to amplifier-output impedance. Therefore, connecting separate woofers in series reduces the damping factor of the amplifier to a value less than 1. This will result in poor transient response. Most amplifiers deliver exactly the same amount of power bridged into a 4-ohm load as they do running a 2-ohm stereo load. To design a subwoofer system that maximizes available amplifier power, keep the following rules in mind: 1. The total system impedance of woofers in parallel can be calculated using the formula: 1 Impedance = 1 1 1 + w + w . . . [. . . ] The total system impedance of woofers in parallel can be calculated using the formula: 1 Impedance = 1 1 1 + w + w . . . w1 2 3 where w is the nominal impedance of the woofer. The total system impedance of woofers in series can be calculated using the formula: Impedance = w1 + w2 + w3 . [. . . ]