The moving iron speaker was the first type of speaker that was invented. This electronics-related article is a stub. A few of the issues speaker and driver designers must confront are distortion, radiation lobing, phase effects, off-axis response, and crossover artifacts. However, if the voice coil mass is reduced below approximately one-fifth So of the optimum value, the efficiency begins to fall off fairly rapidly. Piezoelectric speakers can have extended high frequency output, and this is useful in some specialized circumstances; for instance, sonar applications in which piezoelectric variants are used as both output devices generating underwater sound and as input devices acting as the sensing components of underwater microphones.

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Digital recording Digital signal processing. In these applications, sound quality is a low priority. In practice, all three of these criteria cannot be met simultaneously using existing materials; thus, driver design involves trade-offs.

To reduce the size of commercial products, they are sometimes used as a high frequency driver in electrodynsmic with a conventional dynamic driver that handles the bass frequencies effectively. A typical suspension system consists of two parts: The terms for different speaker drivers differ, depending on the application. However, these designs were significantly limited by their poor sound quality and their inability to reproduce sound at low volume.

Click for automatic bibliography generation. The first experimental moving-coil also called dynamic loudspeaker was invented by Oliver Lodge in Loudspeakers American inventions Audiovisual introductions in Audio engineering Music technology Consumer electronics.

Field coil loudspeaker – Wikipedia

As a simple example of the mathematical physics involved, consider the following: They also have a relatively narrow dispersion pattern that can make for precise sound-field positioning. One can, for the most part, choose only two of the three parameters when designing loudwpeaker speaker system. This raises the resonant frequency of the speaker and increases its efficiency. Additionally, some loudspeakers use the woofer to handle middle frequencies, eliminating the mid-range driver.


The radiation pattern of a combination of point sources is not the same as for a single source, but depends on the distance and orientation between the sources, the position relative to them from which the listener hears the combination, electridynamic the frequency of the sound involved. Rice and Kellogg were able to fully understand the reproduction of all the frequencies necessary to create an accurate audio sound.

However, the influence of room resonances sometimes called standing waves is typically so large that such issues are secondary in practice. The moving-coil principle commonly used today in speakers was patented in by Chester W.

Worked with cathode rays, induction, radioactivity. Copper wires were insulated with cloth.

History and Types of Loudspeakers

He had no way to electroynamic sound to create a useful speaker, but he theorized that this could eventually be done. The inside tab of the ribbon 7 is cemented along the voice coil form, as shown in Fig. This can be reduced by internal absorption using absorptive materials eoectrodynamic called “damping”such as glass woolwool, or synthetic fiber batting, within the enclosure. In the examples that follow, assume for simplicity that the drivers being compared have the same electrical impedance, are operated at the same frequency within both driver’s respective pass bands, and that power compression and distortion are low.

Field coil loudspeaker

When high field-strength permanent magnets became available after WWII, Alnico, an alloy of aluminum, nickel, and cobalt became popular, since it dispensed with the problems of field-coil drivers.


Crossovers can be passive or active. The loudspeaer establishes a concentrated magnetic field between the two poles of a permanent magnet; the outside of the gap being one pole, and the center post called the pole piece being the other.

The coil, which is positioned in the air gap of the magnet, a diaphragm that is rigidly attached to the coil, and the magnetic system constitute the speaker unit see Figure 1.

Why did it take so long to invent the speaker? In typical installations, subwoofers are physically separated from the rest of the speaker cabinets. Contrary to this accepted general belief, I have found it possible’ to design direct-radiator speaklers that have very high efficiencies, comparabl’8 fo the efficiencies realized in horn type loud speakers.

This decreased efficiency from a large diaphragm ‘has been experimentally observed and ooudspeaker led to the general use of -cones having effective vibrating diameters less than 12 inches because it was not-recognized that the -decreased efficiency produced -by -the larger cone was the xresult of a lack of -understanding of the necessary voice coil requirements as set forth in this specification.

Inelectrodjnamic of Tsinghua University demonstrated a thermoacoustic loudspeaker of carbon nanotube thin film, [68] whose working mechanism is a thermoacoustic effect. GE’s Ernst Alexanderson was at the epicenter of wartime communication technology. If mounted on a finite baffle, and these out of phase waves are allowed to interact, dipole peaks and nulls in the frequency response result.

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