Loudspeaker facts for kids

A cheap speaker. It is usually in small radios.

A large speaker.

A loudspeaker, which is also called a loud-speaker or speaker, is an item that is used to create the sound in radios, television sets, and electric musical instrument amplifier systems.

How it works

Loudspeakers use both electric and mechanical principles to convert an electrical signal from a radio, television set or electric musical instrument into sound. For a loudspeaker to produce sound, the signal from the radio, television set, or electric musical instrument needs to be connected to an electronic amplifier.

Loudspeakers are usually built by using a stiff paper cone, a coil of thin copper wire, and a circular magnet. The cone, copper wire, and magnet are usually mounted in a rectangle-shaped wood cabinet. The coil of copper wire moves back and forth when an electrical signal is passed through it. The coil of copper wire and the magnet cause the rigid paper cone to vibrate and reproduce sounds.

Inside the loudspeaker can be a audio crossover.

Types of loudspeakers

Some loudspeakers are designed for lower-pitched sounds, such as woofer loudspeakers or subwoofer loudspeakers. Other loudspeakers, which are called tweeters, are designed to reproduce high-pitched sounds (such as the sound of a whistle or a bird singing).

Loudspeakers for electric musical instruments are usually much stronger and heavier than loudspeakers for radios or television sets. Their main function is to convert electrical signals given to it into sound signals.

History

Alexander Graham Bell invented the first audible loudspeaker in 1876. Bell invented the loudspeaker because he needed a device that would amplify sound for the telephone. In 1878, the inventor Werner von Siemens from Germany patented an improved type of electrodynamic loudspeaker which did not yet include an amplifier..

Images for kids

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  Hi-fi speaker system for home use with three types of dynamic drivers

  1. Mid-range driver
  2. Tweeter
  3. Woofers

  The hole below the lowest woofer is a port for a bass reflex system.
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  Kellogg and Rice in 1925 holding the large driver of the first moving-coil cone loudspeaker

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  Cutaway view of a dynamic loudspeaker for the bass register.

  1. Magnet
  2. Voicecoil
  3. Suspension
  4. Diaphragm
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  Cutaway view of a dynamic midrange speaker.

  1. Magnet
  2. Cooler (sometimes present)
  3. Voicecoil
  4. Suspension
  5. Diaphragm
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  Cutaway view of a dynamic tweeter with acoustic lens and a dome-shaped membrane.

  1. Magnet
  2. Voicecoil
  3. Diaphragm
  4. Suspension
• 

  A four-way, high fidelity loudspeaker system. Each of the four drivers outputs a different frequency range; the fifth aperture at the bottom is a bass reflex port.

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  Exploded view of a dome tweeter

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  Electronic symbol for a speaker

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  An unusual three-way speaker system. The cabinet is narrow to raise the frequency where a diffraction effect called the "baffle step" occurs.

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  A three-way loudspeaker that uses horns in front of each of the three drivers: a shallow horn for the tweeter, a long, straight horn for mid frequencies and a folded horn for the woofer

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  Two-way binding posts on a loudspeaker, connected using banana plugs.

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  A 4-ohm loudspeaker with two pairs of binding posts capable of accepting bi-wiring after the removal of two metal straps.

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  HP Roar Wireless Speaker

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  Specifications label on a loudspeaker

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  Polar plots of a four-driver industrial columnar public address loudspeaker taken at six frequencies. Note how the pattern is nearly omnidirectional at low frequencies, converging to a wide fan-shaped pattern at 1 kHz, then separating into lobes and getting weaker at higher frequencies

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  Moving iron speaker

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  A piezoelectric buzzer. The white ceramic piezoelectric material can be seen fixed to a metal diaphragm.

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  Magnetostatic loudspeaker

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  Schematic showing an electrostatic speaker's construction and its connections. The thickness of the diaphragm and grids has been exaggerated for the purpose of illustration.

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  In Heil's air motion transducer, current through the membrane 2 causes it to move left and right in magnetic field 6, moving air in and out along directions 8; barriers 4 prevent air from moving in unintended directions.

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  Plasma speaker