What Is a Loudspeaker?
A loudspeaker, also called a speaker or loud speaker, is a transducer that converts electrical energy into mechanical energy, providing in the process the audible sound in equipment such as public address systems, studio monitors, guitar and bass amplifiers, radios, televisions, and home stereos.
How Does a Loudspeaker Work?
Loudspeakers work by converting electrical energy into mechanical energy. When an electrical current is passed through a wire coil (or voice coil) in a magnetic field, it produces a push and pull effect that varies with the current being applied. When the voice coil moves in and out, it creates waves of high and low air pressure, which, in turn, create sound.
The Parts of a Loudspeaker
Loudspeaker systems are composed of many different parts including motor, diaphragm, suspension, and frame components.
- Diaphragm (cone) — The diaphragm, or cone, of a loudspeaker determines the frequency response and overall sound it will have. They are often made from lightweight materials and driven by the loudspeaker’s voice coil. When you blast your favorite tunes through a loudspeaker, the diaphragm is what pushes air in and out to create sound.
- Dust Cap — The dust cap is a cover that is placed on the center of the loudspeaker’s cone. Its main job is to protect the cone by keeping out dirt and other debris.
- Surround — The surround, also called the front suspension, is a flexible ring that helps keep the diaphragm or cone from moving side to side, while allowing the voice coil and the cone to vibrate freely.
- Spider — The spider is meant to preserve the voice coil and to ensure all interior parts of the loudspeaker stay in place. It works with the surround as the speaker’s suspension system.
- Voice Coil — This is the winding of wire that can be found wrapped around a loudspeaker’s cylinder. With the help of an alternating current (positive and negative charges), the voice coil interacts with the permanent magnet and its magnetic field to move the diaphragm back and forth, which produces the sound.
- Basket — The basket is a metal frame that holds the speaker assembly together.
- Magnet — The magnet is the “driving force” of a loudspeaker that can be seen pulsating. It can be made from materials like neodymium and ferrite.
- Driver — The driver converts line-level voltage from your loudspeaker’s amplifier into sound by pushing and pulling air molecules in waves; it is another name for the speaker assembly.
- Enclosure — As its name suggests, the enclosure is the cavity where the driver is mounted. Loudspeaker enclosures come in many different designs.
Types of Loudspeakers
The most common type of loudspeaker is a dynamic loudspeaker. A standard dynamic loudspeaker consists of a voice coil, a magnet, a diaphragm, and a cone. The electrical energy output of a power amplifier is transmitted as voltage over a wire to the voice coil. The current flowing through the voice coil produces an electromagnetic field that reacts with the stationary magnet in the loudspeaker assembly. The voice coil is attached to the diaphragm, which is attached to the cone. The magnetic fluctuations cause the diaphragm and, thus, the cone to oscillate, moving air and emitting sound.
There are other types of loudspeaker technology, the best known being electrostatic speakers. These differ from dynamic loudspeakers in that they consist of a thin sheet of electrically conductive film suspended between two wire screens. A high-voltage charge is applied to the film, and it is alternately attracted to one screen and then the other. This creates motion, which again begets sound. Another type of loudspeaker is the servo drive loudspeaker. These speakers employ servo-driven motors attached to the speaker cone in place of the magnet/wire construction. This type of speaker is generally only used in subwoofer applications and, even then, only rarely.