User manual ALPINE SWR-1223D APPLICATION GUIDE

[. . . ] APPLICATION GUIDE Please read this manual to maximize your enjoyment of the outstanding performance and feature capabilities of the equipment, then retain the manual for future reference. Keep the volume at a level where you can still hear outside noises while driving. Driving while unable to hear outside noises could be the cause of accident. Do not use the equipment for purposes other than listed for the vehicle. [. . . ] dEFINITION OFTERMS: Resonance: Most objects vibrate naturally at certain frequencies. If you hang a weight on a spring, then pull it and let go, the weight will bob up and down at a certain frequency determined by the amount of mass and by the stiffness of the spring. Generally, Q denotes how well controlled the movement of the speaker cone is near resonance. qts is the Q , total , of the speaker by itself. When the speaker is placed in a sealed box, the stiffness of the trapped air raises total Q. qtc stands for Q , total , of the closed box system. POWER HANDLING: There are really two completely different types of power handling. Thermal power handling rates how much power the speaker can take without the voice coil melting. This is mostly determined by voice coil size; the SWR-304D/SWR-1223D, SWR-254D/SWR-254E uses a 3" coil for high power handling. Mechanical power handling rates how much power the speaker can take without breaking or tearing; this depends on strongly on frequency and on the enclosure. Mechanical power handling is very difficult to evaluate without actual testing. " As you can see from the graph and table on page five, low frequency output decreases, because the amplifier has to push the speaker against a stiffer air spring. Advantages : Closed box designs are easiest to get good results with. Simply decide whether you want a tight sound (low Q) or a boomy sound (high Q), then size the box accordingly (see table). sealed boxes control cone motion the best. Disadvantages : Compared to free air, a sealed box takes up more room in the trunk. Around 20 to 80 hertz, a ported box can have a higher maximum output. alignments : System Q determines the sound quality. For Q>1, bass sounds boomy due to poor damping and ringing. For Qtc = 1 (a Chebyshev alignment), cone motion shows moderate ringing ; bass is slightly boomy. 707 (the Butterworth alignment), there is no ringing, giving a neutral bass quality. Many consider this the optimum sealed box, a good compromise between size and bass output, with good sound quality. [. . . ] 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. Practically, this means tuning Fb between 20 to 35 Hz. [. . . ]