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.). Today we will look at the first two proposals, audiophile music listening and cinema.

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 either a single diaphragm or multiple diaphragms to perform the same task.

In the early days of music reproduction, a single diaphragm was used; what we called a wide range speaker. Some TV speakers still use this principle with more than ordinary results. Since one element carries all the sounds, they blend together with very little finesse, the sound is 'flat' and lifeless...

The secret lies in the distribution of sound frequencies across several elements. We will then have a loudspeaker combining bass and midrange (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. It should be noted, however, that it is possible to make an excellent two-way loudspeaker in more compact sizes if you invest a little more.

To obtain greater precision, manufacturers will add new elements such as a "midrange" or medium frequency element. This is known as a two-and-a-half way or, in most cases, a three-way speaker. Finally, some speakers will add subwoofers which will reproduce more accurately the lowest sounds such as the bass drum or the lowest notes of a double bass. In short, the more diverse the elements, the more likely you are to get a fantasticspeaker!

The recovery circuit in search of linearity.

 Having several elements to reproduce the music is all well and good, but you have to do it right!

Let's remember our famous "equalizers" that we used to make our listening more lively...

You didn't experience that? (under 30s) It's okay!

The problem is that in the past, the equipment was not very faithful and needed to be enhanced where it could not reproduce the music well. So they would try to equalise the reproduction, i.e. add more highs, mids and lows or subtract them. This had to be done because otherwise it lacked realism as some sounds were muffled while others were a little too high. A minority of people used a measuring instrument to determine exactly what to compensate for, the result was a bit of a mess... JVC Equalizer 

Nowadays, products are better designed so it's the engineers who create new loudspeakers who have that same challenge, to get linear performance so that they hear everything as it is without artefacts. They have to make sure that each speaker element takes effect where the other loses its ability to reproduce. The audiophile will no longer need the electronic crutches that equalizers used to be.

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, without overshoot or undershoot.

We will then speak of linear frequency response expressed in Hertz and kilohertz with the maximum distance from the source expressed in decibels "db" more or less. For example: A response of 20 Hz to 20 Kz + - 1 dB means that over the entire range indicated, there will be no rehashes or attenuation of the sound volume by more than one decibel for certain tones.

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

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

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 size 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 is used to balance the sound by distributing the work between the different elements. Crossovers are used because most individual loudspeakers are unable to cover the entire audio spectrum from low to high frequencies with acceptable relative volume and absence of distortion.

 Tweeter :

Loudspeaker dedicated to high-pitched sounds.

The low end ones are made of paper cones and give poor results. The higher end manufacturers will use different materials such as magnesium, titanium or even rare elements such as beryllium.

The lighter and stiffer the diaphragm, the more accurate and smooth the highs will be to the ear. The reproduction of high frequencies is critical to reduce hearing fatigue, because we feel tired when sounds attack us...

Midrange :

Dedicated midrange speakers.

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 the range most familiar in everyday life...

Woofer :

This loudspeaker gives the lowest frequencies, which are generally used to induce rhythm.

Rigid, with a massive magnet and a large voice coil will be the norm, but it should also be as light as possible in terms of its membrane. A heavy diaphragm will slow down the reaction to signals and delay the end of the movement as ordered by the amplifier, resulting in distortion...

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 loudspeakers of the easy home theatre era with all the components in one kit will make any serious enthusiast break out in hives. What heresy!

The cabinet will be of different designs depending on the tests carried out during its design.

• 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 source of amplification.
• Infinite Baffle: A less widespread principle, this concept is glued to the wall to use it as a resonance chamber. The result is a success in good family products, and the aesthetic/minimalist side will seduce many.

In conclusion, if the product is well designed, it will perform well regardless of the principle used.

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 be able to 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!!!

- Christian

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 From astonishment to ecstasy, to each his own speaker...

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