Editing Tweeter (section)

===Horn tweeter===
A horn tweeter is any of the above tweeters coupled to a flared or [[Horn loudspeaker|horn]] structure. Horns are used for two purposes—to control dispersion, and to couple the tweeter diaphragm to the air for higher efficiency. The tweeter in either case is usually termed a compression driver and is quite different from more common types of tweeters (see above). Properly used, a horn improves the off-axis response of the tweeter by controlling (i.e., reducing) the directivity of the tweeter. It can also improve the efficiency of the tweeter by coupling the relatively high acoustic impedance of the driver to the lower impedance of the air. The larger the horn, the lower the frequencies at which it can work, since large horns provide coupling to the air at lower frequencies. There are different types of horns, including [[horn loudspeaker#Radial, sectoral, and diffraction|radial]] and [[horn loudspeaker#Constant directivity|constant directivity]] (CD). Horn tweeters may have a somewhat 'different' sonic signature than simple dome tweeters. Poorly designed horns, or improperly crossed-over horns, have predictable problems in the accuracy of their output, and the load that they present to the amplifier. Perhaps concerned about the image of poorly designed horns, some manufacturers use horn loaded tweeters, but avoid using the term. Their euphemisms include "elliptical aperture" "Semi-horn" and "Directivity controlled". These are, nonetheless, a form of horn loading.