A horn loudspeaker is a speaker system using a horn to match the driver cone to the air. The horn structure itself does not amplify, but rather improves the coupling between the speaker driver and the air.

Properly designed horns have the effect of making the speaker cone transfer more of the electrical energy in the voice coil into the air; in effect the driver appears to have higher efficiency. Horns can help control dispersion at higher frequencies which is useful in some applications such as sound reinforcement. The mathematical theory of horn coupling is well developed and understood, though implementation is sometimes difficult. Properly designed horns for high frequencies are small (above say 3 kHz or so, a few centimeters or inches), those for mid-range frequencies (perhaps 300 Hz to 2 kHz) much larger, perhaps 30 to 60 cm (1 or 2 feet), and for low frequencies (under 300 Hz) very large, a few metres (dozens of feet). In the 1950s, a few high fidelity enthusiasts actually built full sized horns whose structures were built into a house wall or basement.

With the coming of stereo (two speakers) and surround sound (four or more), plain horns became even more impractical. Various speaker manufacturers have produced folded low-frequency horns which are much smaller (e.g., Altec Lansing, JBL, Klipsch, Lowther, Tannoy) and actually fit in practical rooms. These are necessarily compromises, and because they are physically complex, they are expensive.

The multiple entry horn (also known as a coentrant horn, unity horn or synergy horn) is a manifold speaker design; it uses several different drivers mounted on the horn at stepped distances from the horn’s apex, where the high frequency driver is placed. Depending on implementation, this design offers an improvement in transient response as each of the drivers is aligned in phase and time and exits the same horn mouth. A more uniform radiation pattern throughout the frequency range is also possible. A uniform pattern allows smooth arraying of multiple enclosures.

Both sides of a long-excursion high-power driver in a tapped horn enclosure are ported into the horn itself, with one path length long and the other short. These two paths combine in phase at the horn’s mouth within the frequency range of interest. This design is especially effective at subwoofer frequencies and offers reductions in enclosure size along with more output

This article includes material from “Loudspeaker enclosure.” Wikipedia.https://en.wikipedia.org/wiki/Loudspeaker_enclosure  Licensed under Attribution-ShareAlike 3.0 United States (CC BY-SA 3.0 US) https://creativecommons.org/licenses/by-sa/3.0/us/ Authors:https://en.wikipedia.org/w/index.php?title=Loudspeaker_enclosure&action=history