INFO SONXPLUS: The speakers: The most critical link in your stereo system.

My Info-Sonxplus capsules aim to familiarize you with the technologies and equipment used in audio and visual reproduction at home. To make wise purchases, it is important to know what you are buying.

In our previous column we looked at the basics of music reproduction, now let's move on to the distribution of all that beautiful sound.

No matter what you listen to, speakers are everywhere, furnishing our otherwise silent spaces. There are several types of speakers for different applications (cinema, audiophile precision listening, outdoor sound, home automation integration, commercial use, etc.). Here we will look at the first two proposals, audiophile music listening and cinema use.

Basic principles.

The loudspeaker must be able to reproduce the full range of life's sounds, from the lowest to the highest pitched. This can be achieved by using a single diaphragm or several elements to accomplish this task.

In the early days of music reproduction, a single diaphragm was used; this is what we call a wide range speaker. Some TV speakers still use this principle with more than ordinary results. As a single component diffuses all the sounds, they blend together with very little finesse, the sound is dull and lifeless...

The secret lies in the distribution of audible frequencies across several elements. We will then have a loudspeaker combining the bass and midrange speaker (woofer) and a tweeter, which is the beginning of the high-fidelity approach. This is called a two-way speaker.

This approach will be used in more affordable and often smaller speakers. Although performance may suffer, it should be noted that an excellent two-way loudspeaker can be achieved in these more compact formats if a little more investment is made. 

To achieve greater accuracy, manufacturers will add new components to their boxes, such as a midrange element. This is referred to as a two and a half way speaker or in most cases a three way system.

Finally, some speakers will add subwoofers that will more accurately reproduce the lowest sounds such as the bass drum or the dullest notes of a double bass. In short, the more diverse the elements, the more likely you are to get a fabulous speaker!

The recovery circuit in search of linearity.

Using multiple components to reproduce music is all well and good, but it has to be done properly!

Let's remember our famous "equalizers" of yesteryear that we used to make our listening more lively... You didn't know that? (those under 30 years old) It's not a problem! The problem is that in the past, the devices were not very faithful and needed an enhancement where they could not reproduce the music well.

The aim was to equalise the diffusion, i.e. to add more highs, mids and lows, or to subtract them. This had to be done because otherwise it lacked realism as some sounds were muffled and others were a little too high. A minority of people used a measuring instrument called a sound spectrum analyser to establish exactly what had to be compensated for, without this instrument the result was unfortunately what we would call today: nonsense...

Today, products are better designed as engineers create new loudspeakers with the same challenge of achieving linear performance to hear everything as is without artefacts. They must ensure that each speaker element takes effect where the other loses its ability to reproduce. The audiophile will no longer need the electronic crutch that was the equalizer.

To design an excellent loudspeaker box, engineering will consider a proper selection of diaphragms according to their individual properties, followed by the creation of the circuitry for chopping and routing the sounds according to their frequencies to adapt the distribution of work according to the resonance of the diaphragms and the loudspeaker box.

The electronic circuit used to do this work is called the crossover circuit.

Thus, the woofer may stop reproducing higher frequency sounds while the midrange driver takes over, and so on. The aim will be to ensure a full response across the entire range, with no highlights, sags or coloration.

We will then speak of linear frequency response expressed in Hertz and kilohertz with the maximum distance from the source as a reference point. It will be formulated this time in decibels "db" which is a measure of sound intensity. For example: A complete and audible response from 20 Hz to 20 Kz + - 1 dB will mean that over the entire range in question, there will be no rehashes or attenuation of volume by more than one decibel, giving high fidelity.

 Choose between shelf or tower speakers.

There are two main categories of speaker formats, the bookshelf and the full size tower. "Tower

The only reason to choose one or the other is the space you have available.

The full-size speaker will always be your best choice for the most truthful performance, but if you don't have the space, a small-format speaker will do just as well.

Why is the larger format desirable?

A: Just a question of physics, to move the air easily and produce imposing sounds without restriction, we need an imposing source...

N.B.: One consideration that is frequently raised is aesthetics, as full size boxes are more visible in the room than smaller ones. Ultimately, this is less of a problem than it used to be, as manufacturers have corrected this by integrating the "look" of the box itself into the design prerogatives. Gone are the big, square, crude imitation wood boxes, we now have beautiful, neat finishes that will enhance your decor, no matter what your style!

Glossary of typical loudspeaker components.

Terminal block :

 This is the point of entry for the electrical current, and a good connection will ensure stable performance. The quality of the wires is also very important and will be discussed in a subsequent column.

 The recovery circuit :

As described above, it serves to balance the sound by distributing the work between the different elements. Crossovers (are used, as most individual loudspeaker diaphragms are unable to cover the entire audio spectrum from low to high frequencies with acceptable relative volume and absence of distortion and coloration.

 Tweeter :

Loudspeaker dedicated to high-pitched sounds.

 Low-end units are made of paper cones and perform poorly.

Good quality manufacturers will use different materials such as magnesium, titanium or even rare earth elements such as beryllium.

These more expensive materials will be essential, as the lighter and stiffer the diaphragm, the more accurate and smooth the high frequencies will be to the ear. The reproduction of high frequencies is critical to reduce hearing fatigue, because if left unchecked, they can easily become shrill and aggressive.  

 Midrange:

Loudspeakers dedicated to intermediate frequencies. It should also be very light and will allow the reproduction of the human voice and instruments in general. It is here that the distortion will be most apparent, as the sounds reproduced will be in this more familiar range of everyday life...

 Woofer:

This loudspeaker gives the lowest tones which are generally used to induce rhythm. It has a rigid diaphragm, a massive magnet and an imposing voice coil, but it must be light enough to not interfere with the control requirements of the amplifier.

The Sub Woofer :

This is an auxiliary loudspeaker to get as much bass as possible. It is usually self-contained and in a separate box. It is often used in home theatre, and can sometimes be useful in stereo listening, but should be used sparingly. This will be the subject of a separate review.

 The case :

The cabinet forming a loudspeaker must be made of wood. Wood has a natural ability to absorb vibrations, which leaves room for the music. The plastic speakers of the easy home theatre era with all the components bought in one box will give any serious enthusiast a rash. What heresy!

 The different housing concepts :

•  Closed: The loudspeaker has no openings and is completely sealed. It therefore uses only its front surface for propagation.
•  Bass Reflex: A port, sometimes referred to as a "power flow" port, is present at the front or rear to increase bass output. The use of a surface such as a wall is used to increase the output when a rear outlet is used. There is a third technique called "Down Firing" which uses the floor as a natural source of amplification.
• Infinite Baffle This concept uses the wall as an external sounding board. The result is successful in good family products, and the aesthetic/minimalist aspect will appeal to many.

Aesthetics

 In this day and age, tastes are becoming more refined, so although this factor of personal preference has nothing to do with performance, the choice of finishes and shapes is the final consideration for purchase, but while we are on the subject of indulgence, let's add the sense of sight to the sound!

 The last word

 You are now better equipped to shop for your speakers... The most important thing is to listen. Only attentive listening supported by good explanations from a competent advisor will allow you to successfully complete your project and justify your investment. If you have never heard a very good loudspeaker, I invite you to do so, because there are marvels to be discovered, almost infinitely renewable pleasure!

 It's a passion!!!

 Thank you for reading

 - Christian

Next article:

Affordable audio buying guide.