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

These Info-Sonxplus capsules are designed to familiarize you with the technologies and equipment used in home audio and visual reproduction. To make wise purchases, it's important to know what you're buying.

In a 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're listening to, speakers are everywhere, furnishing our otherwise silent spaces. There are many different types of loudspeaker for different applications (cinema, audiophile precision listening, outdoor sound, home automation integration, commercial use, etc.). Here, we'll look at the first two: 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" loudspeaker. Some low-cost TV speakers still use this principle, with more than ordinary results. As a single component diffuses all sounds, they blend together with very little finesse, resulting in a dull, lifeless sound...

The secret lies in the distribution of audible frequencies across several elements. The result is a loudspeaker combining a bass/midrange driver (woofer) with a tweeter, marking the beginning of the high-fidelity approach. This is known as a two-way loudspeaker.

This approach will be used in smaller loudspeakers. Although performance is likely to suffer, it should be noted that it is possible to make an excellent two-way loudspeaker in these more compact formats, provided you invest a little more.

To improve sound quality, manufacturers will integrate additional components into their equipment, such as a midrange driver. The result is a 2.5-way speaker or, in most cases, a three-way system. 

Finally, some loudspeakers will add subwoofers for more accurate reproduction of the lowest sounds, such as the bass drum or the muffled notes of a double bass. 

In short, the more diverse the elements, the more likely you are to get a fabulous enclosure!

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!

Remember the famous equalizers of yesteryear that we used to make our listening more lively? Didn't you know that? (under 30s) It's all right! The problem is that, in the past, the devices weren't very faithful and needed to be enhanced where they couldn't reproduce the music properly.

We then sought to equalize the diffusion, i.e. add more treble, midrange and bass, or subtract some. This had to be done, because otherwise it lacked realism, with some sounds muffled and others a little too high. A minority of people used a measuring instrument called a sound spectrum analyzer to establish exactly what needed to be compensated,

without this instrument, the result was, alas, what we would call today: nonsense...

This absence of linearity is what we called linear distortion in our previous review. To have audio truth, you need to have the minimum difference in intensity between the sounds produced by the loudspeaker and the original source.

 JVC Equalizer 

NowadaysNowadays, products are better designed as engineers create new loudspeakers with the same challenge of achieving linear output so that everything can be heard as it is, without artifacts. They have to ensure that each loudspeaker 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 the right selection of diaphragms according to their individual properties, followed by the creation of the circuit for chopping and routing 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.

In this way, the woofer can stop reproducing higher-frequency sounds, while the midrange driver takes over, and so on. The aim will be to ensure full response across the entire range, without harshness, sagging or coloration. In short, when one membrane becomes less effective, the next unit handling the audible frequencies that the first can no longer produce will take over. 

We then speak of linear frequency response expressed in hertz and kilohertz, with the maximum distance from the source as the reference point. This time, it's expressed in decibels (db), a measure of loudness. For example: A complete and audible response from 20 Hz to 20 Kz + - 1 dB will mean that, over the whole range in question, there will be no rehauts or volume attenuations of more than one decibel, giving high fidelity.

Shelf or tower speakers?

Enclosures can be divided into two main families: bookshelves and full-size models, commonly referred to as towers. "Tower

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

Paradigm Persona B

For the most authentic sound reproduction possible, don't hesitate to opt for a large speaker. However, if space is limited, a compact model will also fulfill this function. However, to achieve similar performance, you'll need to invest an equivalent amount in a bookshelf as in a tower.

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, since 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 at our disposal neat, beautiful finishes that will enhance your decor, whatever 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. Solid, gold-plated terminals with the possibility of "banana" type connections will be a requirement here. The quality of the wires is also very important, and we'll come back to this in a subsequent column.

The recovery circuit :

As explained earlier, it serves to balance the sound by distributing the workload between the various elements. Crossovers are used because most individual speaker diaphragms are incapable of covering the entire audio spectrum from low to high frequencies, with acceptable relative volume and an absence of distortion and coloration.

 The tweeter :

Beryllium driver dedicated to the highest-pitched sounds.

The lower-end are made from paper cones which give poor results.

High-quality manufacturers will use various materials, such as magnesium, titanium or even rare-earth elements like beryllium.
These more expensive materials will be indispensable, as the lighter and more rigid the membrane, the more precise and softer the highs will be to the ear. High-frequency reproduction is critical to reduce hearing fatigue, as uncontrolled high frequencies easily become strident and aggressive. Also, left-right differentiation is greatly affected by high-frequency precision.

The mid-range:

Loudspeakers dedicated to intermediate frequencies. These too should be very light, so as to reproduce the human voice and instruments in general. This is where distortion will be most apparent, as the sounds reproduced will be in this more familiar range of everyday life. Like the tweeters, it will be more directional than the bass, allowing good left and right differentiation.

Woofer:

This loudspeaker produces the lowest tones, generally used to induce rhythm. With its rigid diaphragm, massive magnet and imposing voice coil, it must nevertheless be light enough not to interfere with the amplifier's control requirements, known as the damping factor. (see related chronicle)

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

Sub Woofer:

This is an auxiliary loudspeaker to obtain the deepest bass possible. It's usually self-contained in a separate box. It's often used in home theater, 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, leaving room only for the music. The plastic loudspeakers of the easy home theater era, with all components bought in a single box, will make any serious enthusiast break out in hives. What heresy!

The case will come in a variety of designs, depending on the tests carried out during the design phase.

• Closed box : 

The loudspeaker has no openings and is completely sealed. It uses only its front surface for propagation.

• Bass Reflex camera :

A bass reflex system (also known as a vented enclosure or reflex port) is a type of loudspeaker enclosure that uses a port (hole) or vent cut into the enclosure and a section of tube or pipe attached to the port. 

 When a rear output is used, a surface such as a wall is used to accentuate output. There's a third technique, called "Down Firing", which uses the floor as a source of amplification.

• Infinite Baffle" principle : 

  A less widespread principle, this concept uses the wall as an external sounding board. The result is successful in products from good families, and the aesthetic/minimalist aspect will appeal to many. Sometimes referred to as "lifestyle".

• With passive radiator:  

  Passive radiators work in a similar way to ported bass reflex systems, and both methods are used for the same reason: to extend the system's low-frequency response. A passive radiator consists of using one or more additional cones (diaphragms) in a cabinet instead of vents. These passive diaphragms have no magnet or voice coil, and are not connected to a power amplifier. The backward movement of the woofers by pressure will cause the passive radiator to act, increasing the sound box's bass efficiency.

  The conclusion is that, if the product is well designed, it will perform well, whatever 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, there are a variety of finishes and shapes to choose from. This will be the final consideration for the purchase, but as long as we're indulging ourselves, let's add the sense of sight to that of hearing!

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

Paradigm Persona 9