User manual ALPINE SWR-304ED

[. . . ] Driving while unable to hear outside noises could be the cause of accident. Arrange wiring and cables in compliance with the installation manual to prevent obstructions when dirving. Cables or wiring that obstructs or hangs up on places such as the steering wheel, gear lever, brake pedals can be extremely hazardous. [. . . ] Mechanical power handling is very difficult to evaluate without actual testing. Alpine tests speakers at full power for 96 hours to confirm the mechanical toughness of each woofer. SPEAKER OUTPUT: Sound pressure level (SPL) is determined by how much air the woofer moves. This is set by the woofer's surface area Sd and by its excursion (motion back and forth). Maximum output at low frequencies is set only by the woofer's excursion (movement) capacity, since most amplifiers have enough power to drive most woofers to full excursion at low frequencies. Equalization can change the sound balance, but will not affect maximum output. ENCLOSURES (BOXES): Designing and building the best speaker enclosures takes time, tools, and know-how. If you don't have a lot of experience, consult a professional who has designed and built successful enclosures. If the woofer isn't enclosed, the sound just moves from the front to the back of the speaker, and you won't hear much bass. Tips: For best results, try to make the box rectangular instead of square, and mount the driver(s) offcenter. Port ends should be spaced at least one diameter from any obstructions to breathe properly. If the speakers are not connected to the same amplifier channel, they should be in separate cavities. Please note that rear hatch covers do not isolate very well and are not usually strong enough to support the weight of a subwoofer. disadvantages: In most cars , the trunk leaks to the passenger compartment. Therefore, free air mounting will lose bass output compared to a boxed woofer. Since the woofer is not loaded by box air pressure, it handles less power. [. . . ] Alignments: Ported boxes also have alignments, many more than the scope of this Guide. Very motivated individuals should look at the References for more information. Tips: Fb should be kept below the lowest bass note you want to reproduce. [. . . ]