Hi

Would you please help me to know the fundamental difference between horn speaker and 'normal' speaker? Is this anything have to do with the sound quality? Isn't the sound quality of horn speaker bad as compared to normal speaker, and isn't horn speaker specifically made to amplify human voice only and is not suited for music playback? But I think the sound produced by horn speaker can go a long way.

horn speaker: http://image.made-in-china.com/2f0j00WBtTJuYnCpcw/Horn-Speaker-YH25-1-.jpg

normal speaker: http://www.officialpsds.com/images/thumbs/Vector-Speaker-psd15015.png

Regards
PG

 

A properly designed horn speaker can be just as good as a sealed box or a vented box. Horn speakers are ususally folded horns so they will fit inside a house. All speaker boxes are about coupling the movement of the speaker to the air around it. There are several ways to do this, and they are well known because they work.

 

The job performed by a loudspeaker is one of converting electrical energy into sound energy. Sound itself is a succession of compressions and rarefractions in the atmosphere, so the problem is one of converting the electrical signal into "pressure waves".

The obvious method is to convert the audio signal into the movement of a diaphragm, which then propagates the pressure waves in the air. This would be termed a "direct radiator", and it comes in 2 forms: small and large (as compared to the wavelength of the sound wave in air).

By far the most common is the small direct radiator (commonly a cone). With one of these, it's quite convenient to mount it in a sealed (or semi-sealed) box, which has the advantage of removing the unwanted back-radiation. However (apart from other shortcomings) there is a fundamental disadvantage: the small diaphragm isn't very good at converting its motion into sound waves (because of its lack of size). It tends to just flap about, whilst disturbing the air only minimally. Thus, even with an efficient motor system, the small direct radiator has very low efficiency (usually a lot less than 5%, if my memory serves me).

The large direct radiator is typified by the electrostatic loudspeaker. This is effectively a large panel driven by (necessarily, in practice) weak electrostatic forces. It would be quite efficient (because of its ability to couple to the air), but the weak motor system is the limiting factor here.

So much for direct radiators. However, there is another method of converting the electrical signal into sound waves: the horn-loaded pressure transducer. Here, the progressively increasing cross-sectional area of the horn has the effect of coupling the high-acoustic-impedance present at the horn's throat to the ambient air's low impedance - similar to how an electrical transformer is used to couple high-impedance circuitry to low-impedance circuitry.

Since the motor system for a horn loudspeaker can be equally as efficient as that used in the cone speaker (and often a cone drive unit is used as the motive force at the throat of a horn), overall efficiency can be very high (say 50%). In fact, high efficiency is why most horn loudspeakers exist - they're very commonly used in low-quality public address applications.

But they're not all low quality. Although there are severe difficulties in realising a high-quality horn loudspeaker (not least the need for multiple horns to cover the audio spectrum), it is possible to get very acceptable quality. In fact, some enthusiast swear by them - though they're rather thin on the ground, as are the manufacturers.

If anyone is thinking of trying a high quality horn loudspeaker, do note that the high efficiency will require that the amplification is very good at driving the low power levels!

 

The cheap PA horn speaker sounds loud but also sounds awful (tinny sound). It produces no low frequencies and probably also produces no high frequencies.

 

All the above, plus the horn can be used outdoors where the weather won't bother it.