So what really is the differance between loudspeaker configurations..

This is an interesting and often controversial question. If you listened to all the advertising hype you could be forgiven for believing the differences between sound systems were huge.

In order to make rational comparisons with audio technology it is necessary to place these systems into groups so we are comparing apples with apples.

Over the years the market has tended to swing between the so-called “Bass Reflex” or “Composite” type speaker enclosure design and the “Horn Loaded” concept. More recently however a concept that was resoundingly dumped many years ago called the “Line Array” has once again entered the competitive fray and while the idea is as old as the hills it is being sold as the very latest thing and representing a major technological breakthrough. What baloney!

These three concepts all have their own advantages and disadvantages and also work better than the others in certain circumstances. The idea that one design can work well in all situations is a myth perpetrated by misleading advertising and misinformation.

One of the most important things to remember about sound systems is the fact that they are highly reliant on the environment they are used in as far as their ability to create an impression is concerned. This can be indoors or outdoors and the differences can be equally astonishing.

In order to gain a meaningful impression of a large sound system you need to hear them in identical listening conditions. If this is not possible, opinions are of little value. Up to 80% of what we hear can come off the walls of the venue, so you can imagine what effect that much reflection has on our ears. It can also make a sound system sound far louder than a building with little reflection. The tonal response is affected as well. The amount of reflection varies between the front and the rear of a venue also. As we move away from the speakers it tends to get much worse as we leave the “Near field” and enter the “Far field.” Horns and line arrays extend the near field thus improving clarity towards the rear of a room.

Composite systems.

Composite systems usually consist of a collection of speaker enclosures that have been ground stacked or strung together by flying hardware in a flown cluster or an array. The fidelity of a well designed composite enclosure is indisputable but this performance can change when they are harnessed together in groups. This is because of a nasty lurgy commonly known as phase shift. Phase shift can result in often audible peaks and dips of the frequency response of a sound system meaning that the sound pressure is not even at all frequencies throughout a venue. This is particularly evident in rooms that have very good acoustics because the spread of sound is not affected by reverberation, which can easily mask phase shift aberrations.

Speaker system manufacturers make various claims about the way their respective systems close couple but these cannot be substantiated in normal terms because it is not possible to do the same tests they have done unless you had identical conditions. Often these kinds of specs are meaningless anyway. All sorts of amazing claims get made but the simple fact remains: if the human ear can hear sound coming two different places simultaneously if they are at different distances apart then phase cancellation will occur because it must.

Horn loaded systems.

Horn loaded systems also suffer from phase shift problems but the sound is much more controllable. Ie: It tends to go where you steer the horns. This means you can accurately target a given area and the overlap tends to be less of a problem than with composites because the sound field footprint is more defined. Horns also have the big advantage of being able to avoid reflections from wall surfaces, which can make a huge difference to clarity. Reverberation is substantially reduced and they produce a more “In your face sound.”

As horn loaded systems are very efficient they produce far more sound for there size in the mid / high region than conventional enclosures do because you need less of them for the same or better output.

Horns are difficult to mount because of their strange shape and they have a reputation of sounding “horny.” Modern technology has had a positive impact on this attitude and new more progressive flare and driver designs have greatly improved this impression. At an international level sound companies have waxed lyrical about both concepts since God was a boy and probably always will. There are basically two schools of thought and they will always have their own preferences.

Line array systems.

Touted, as being the best things since the advent of the loudspeaker this concept is as old as the ark! A collection of composites is hung in a string, to form a vertical array. New acoustic lens technology has supposedly corrected the mid / high frequency comb filter effect that usually results from the interaction between the high frequency components at the overlap and reduced this to a minimum. There are various ways of doing this but basically what is achieved is time alignment. By exciting the sound from the lens so that it arrives at the mouth of the lens in a flat wave front additions and cancellations are avoided.

The down side is that they must hang in a long string, they are very inefficient and need a lot of power to drive them compared to horns and they do not have the same impact as a ground stacked system does. The other big negative point is the fact that unless the coverage footprint is adjusted so that a full overlap occurs they must be regarded as a monoral system. For those who are interested in some more advanced reading will be found by using the following link. It leads to a web site written by an Australian friend of mind of some thirty five years standing, Mr. John Burnett. John co founded the audio school SAE, but soon disassociated himself from it when the direction began to differ from his original vision of how audio should be taught to paying students. http://lenardaudio.com/education/07_horns.html

Conclusion.

It is the nature of the beast for audio manufacturers to pursue the marketing edge. The arguments about what is the best and what won’t work so well have been going on since the advent of audio reinforcement itself. At the end of the day everyone will have their own individual opinions but it is important to always remember that it is the objective ones that have the real meaning.

In the next few years we are likely to see the emergence of some incredibly powerful wide range horns and the line array system will disappear. Bass always performs best when the subs are mounted at ground level and mid / highs always perform best when they are flown. Line arrays may give even coverage but they hang in a line, so if you want to project video or light onto the rear of a stage cavity you can forget it. Horns are very efficient but they have a characteristic sound that may not suit everyone and they can be complicated to mount and align correctly. Composites may sound sweet but they don’t couple very well, take up a lot of space and are heavy and clumsy to fly. Involving an expert can be well worth while before committing to a speaker system concept. You may pay for the service but their fee may save you far more than the cost in the long run.