Audio Speaker Working Explanation

Audio speakers are very much used in our daily life. Every day you may hear recorded music, news on your smartphone, radios or TV, even in stores and streets. But, do you know how does it works?

The working principle of Audio speaker is very simple, you can easily understand it. Basically, it's working on the interaction of the permanent magnet and the electromagnet. Below, we will focus our attention on the various aspects of the audio speaker.

Audio speaker

What is an Audio speaker?

An Audio Speaker or loudspeaker or speaker is an electronic transducer that converts an electrical audio signal to a corresponding sound.

What is an Audio speaker
The Audio speakers are round-shaped. The main reason is that a speaker can physically move a lot of air and that means the diaphragm has to go a relatively long way. This 'long throw' diaphragm movement requires very flexible surroundings that cannot be filled in as non-circular forms.

The size of the audio speaker dictates the frequency. To make higher frequency waves, the diaphragm has to vibrate faster. It's harder to get the diaphragm moving fast in a large cone. Similarly, it would be very difficult for a small driver to vibrate at a slow enough rate to produce low-frequency sounds.

See also: Audio Amplifier with Single Transistor.

Main parts of Audio speaker

The main parts of an audio speaker are:
  1. Permanent magnet.
  2. Voice coil.
  3. Protective cap.
  4. Suspension.
  5. Diaphragm.
  6. Voice coil terminal.
  7. Metal case.

Audio speaker Cutaway
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Audio speaker Cutaway
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An audio speaker has a permanent magnet and a coil of very thin copper wire is used as an electromagnet.

We already know that if current flow through a coil then it becomes an electromagnet which pole can be changed, but the poles of the permanent magnet cannot be changed. This copper wire is called Voice coil.

A lightweight diaphragm (or cone) which connected to a rigid basket, or frame, via a flexible suspension. It constrains with a voice coil which moves axially through a cylindrical magnetic gap.

Do you know why are audio speakers cone-shaped? - The purpose of the cone assembly is to accurately reproduce the voice coil signal waveform.

A protective cap glued in the cone's center to prevent the voice coil from dust.

Permanent magnets are placed in a frame of a metal case.

Types of Audio speaker

There are three basic types of audio speakers, produce different types of audio sounds.
  1. Woofer speaker: A woofer or bass speaker is an audio speaker, designed to produce low-frequency sounds, with a range from 20 Hz up to 500 Hz. Generally, it used to cover the lowest octaves of an audio speaker's frequency range.
  2. Tweeter speaker: A tweeter or treble speaker is a special type of audio speaker, designed to produce high audio frequencies, with a range from around 2,000 Hz to 20,000 Hz.
  3. Mid-range speaker: A mid-range or squawker speaker is an audio speaker that reproduces sound in the frequency range from 250 to 2000 Hz. It used in three-way multi-driver speaker systems
Individual speakers provide their best performance within a limited frequency range and mainly size-related. But their working principle is the same.

Working principle of Audio speaker

The working principle of an Audio speaker is, when an alternating current electrical audio signal from an audio device fed to the coil, immediately the copper coil behaves as an electromagnet and generates the magnetic pole.

If the same pole is generated in the electromagnet as the permanent magnet pole, they repulse each other otherwise, they attract each other. The magnetic coil is forced to move rapidly back and forth due to Faraday's law of induction.

Because the voice coil is very light in weight, it moves up and down according to the pulse current or signal with audio speaker cone (diaphragm). For this, it pushes the air and creating sound waves.

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