The tale of the broadband speaker


Created on 27.01.

Updated 04.17.2020 08:44.

Author: Dmitry Pirozhkov.

Sound is an integral part of human society. With the first breath of life, a person hears a variety of sounds. That is why it is impossible to imagine a soundless modern civilization. Technologies have penetrated into all corners of human life, they also allow you to get the widest range of various sounds.

To hear sounds, a person has a universal natural apparatus – hearing. To emit sounds in all natural ranges, the sound emitter was created by engineering thought. It is such a device that uses the ability of the human ear to detect excited mechanical vibrations.

What is a full range speaker?

As progress developed, many products were invented that emit sounds of a wide variety of ranges, but the most popular was the electrodynamic loudspeaker. The speaker design is quite simple and versatile. An audio frequency voltage is applied to a coil inside a permanent magnet. The vibrations generated by the coil are transmitted to the diffuser. The mechanical vibrations generated by the coil are transmitted into the air. The ear picks up these mechanical vibrations and the person hears the sound.

Considering that you want to listen to music and other programs accompanied by sound always and everywhere, there is a need to create a universal sound emitter. Specialized speakers work great in a narrow range, but this is far from necessary and not always. But the middle frequencies are in demand the most.

That is why it became necessary to create popular full-range speakers, which, along with the mid frequencies, reproduce both low and high. Of course, it is impossible to reproduce the entire range of sounds on one radiator, but the demand for such speakers is due to a number of reasons. First of all, the fact that the design of highly specialized emitters is often quite cumbersome. In addition, the price of such products is higher, because you have to pay for the quality. Not everyone can afford it.

A full-range speaker is an economical option where one speaker reproduces the entire frequency band.

But pop music with the news, as well as music in the car, is quite possible to listen to without a crossover through a cheap broadband speaker. This explains the steady popularity of broadband systems. Household appliances, smartphones, TVs, portable speakers – broadband speakers have found their way everywhere.

In addition, universal transducers designed for a wide sound range are installed in horn systems and Voight tubes.

Horn acoustic systems

Manufacturers face a number of challenges when trying to tame as much of a range of sounds as possible with full-range speakers. It all depends on what range of sounds you want to produce.

Low sensitivity systems exhibit a narrow dynamic range, especially when the volume is turned down. This is expressed in the loss of high and low components, which are “clogged” by the mid-frequency sound. This is partly due to the structure of the human ear, which is most optimally adapted for the perception of medium sounds.

When it comes to high frequencies, the sound emitted by the small diaphragm of the tweeter with a small amplitude is simply lost against the background of the same mid frequencies. The solution to this problem is found in the use of additional devices (timbre blocks, frequency response correctors, tone compensators, etc.) that impair sound reproduction.

The alternative is a fundamentally different way of improving sound reproduction – improving the efficiency of acoustic systems using horns (horns). This original design makes it possible to correlate the pressure of the external air environment and the sound pressure of the diaphragm of the radiators. This leads to minimization of distortion and equalization of the amplitude-frequency characteristics of full-range speakers.

In the Soviet Union, they were very fond of creating horn acoustic systems based on broadband 4A-28, for example: An acoustic unit with increased efficiency at low frequencies.

Rice. 1. Broadband speakers 4A-28

Voight Trumpet

In 1930, Paul Voight described a new principle for creating a speaker system, the so-called Tapered Quarter-Wave Pipe (TQWP). This horn system uses the resonance frequency of the driver.

The advantage of the acoustic principle is the absence of cross-over filters. The horn and speaker are separated, that is, the placement of the speaker is not the beginning of the speaker, but its side. The horn acts as a reverse load for the diffuser.

And again, our radio amateurs built Voight pipes, again !, on speakers 4A-28.

Broadband speaker design

There are two main types of universal broadband speakers – with a central cap and a cone-visor “pipe”.

The first design is more like a conventional single-cone speaker.

Rice. 2. Broadband speaker Visaton B 200/6 with a center cap

But the structure of the second variation of the speaker is more complicated, again the same 4A-28. Such a radiator contains two cones: a large one, as in conventional speakers, and the second one, built inside a large one.

The diaphragm should be medium in size with moderate vibration. Otherwise, high-frequency sound will receive more distortion. As for the bass, then the solution is to increase the size of the cone, with the same stroke, but with a high-quality diffuser.

Today, there are many not only options for the execution of full-range speakers, but also the materials used in the manufacture of diffusers. Manufacturers go to great lengths to minimize distortion. Some radiators with high efficiency distort low frequencies, others require the use of a special box to increase bass. Using amplifiers up to 3 W in the designs of full-range speakers, high performance is achieved.

Since when using broadband speakers, you want to listen to the entire frequency range (high, medium, low) as qualitatively (as possible), manufacturers use paper or a modern alternative to it, Kevlar, in the manufacture of the diffuser. This way it is possible to achieve a much better result.

In addition, there is a unique experience of application as a suspension … of leather. For example, in the manufacture of broadband speakers Kondo RUTHY-1-2-4 and Ongaku speakers, suede is used for the suspension. Unusual approach, but excellent sound clarity is achieved. In particular, a study was carried out on a broadband ADVENT, 2 bands: 25 cm LF + squeaker, a closed box of 60 liters.

A design feature of the speaker is the uneven skin tension in the RCA-TELEFUNKEN gimbal. The closer to the diffuser, the higher the tension. As a result, a quiet sound, excellent in its purity.

Rice. 3. Leather surround in full-range speaker

Read more about leather suspension in the article “The Dignity of Quiet Sounds”.

Also interesting are the studies of acoustics made with magnetized speakers from the company …