No one likes grainy, undefined sound when listening to their favorite tracks. Typically overlooked, the electric speaker has made a sizeable impact on our quality of life, and it would be hard to imagine what life would be like if it had never been invented.
Created based on the works of Thomas Edison and his ilk, electric speakers began to gain prominence in the 1920s, a time when the phonograph or gramophone was the acoustic technology that many utilized to listen to their favorite tunes. Back then, a speaker was typically of the horn design, simply providing a megaphone like effect to amplify sound waves. Since then, the electric speaker has progressed through many iterations each still maintaining the same basic design. The electric speaker unquestionably has influenced all of our lives, but how do they work? In this article we’ll cover the basic anatomy of this incredibly useful device.
The most basic form of electrical speaker, the dynamic loudspeaker, is comprised of a cone of lightweight material, which can be made of paper. It can also be made of a similarly light but stronger mesh of carbon fiber. Regardless of the material it is comprised of, a cone is invariably connected to an internal structure referred to as a basket. As the cone needs to vibrate freely for sound to be generated, the two are connected utilizing a suspension system, which will allow the cone to perform as a diaphragm.
Next, the apex of the cone is where a voice coil can be found. The coil itself is composed typically of copper wire and is wrapped loosely around a magnetic south oriented pole that receives a current. Around this series of components is another magnet, this time attuned to magnetic north. The way these magnets interact with the coil is what is referred to as Faraday’s Law. This is a law which states that when passing a magnetic field through a copper coil, a voltage will be “induced”. This, in turn, will cause the copper coil to move. Once the coil starts to move, the cone, which is poised directly above the coil, will start to vibrate. Since all sound is vibration, adding an audio waveform to the coil causes the cone to vibrate at the precise wavelength to produce audible sound.
Since the coil can move in any direction when the current passes through it, “spiders” are utilized. These spiders stabilize the coil and ensure that the coil itself only moves upwards and downwards when receiving the appropriately induced current.
Directly above the coil and in the center of the cone a dust cap is typically poised. As dust can hinder the operation of either the magnets or the coil itself, the dust cap prevents the accumulation of foreign particles on the assembly.
Human hearing accommodates an active range of roughly 20 HZ to 16,000 HZ. As a result of this, all of today’s speaker system must have a vibratory range within these audible parameters. To accomplish this, many manufacturers utilize multiple cone set ups in order to accommodate the full range of human hearing. To produce deeper, richer tones a larger cone is required, while higher pitches require a smaller, faster vibrating cone. The speaker setups that most accurately convey the full range include tweeters, squawkers, and subwoofers.
• Tweeters – This type of speaker feature or drive covers the range of notes requiring the cone to vibrate quickly. Just as the name sounds, the notes it produces re high pitched. Tweeters can handle sound even higher than the range of human hearing, sometimes higher than 20,000 HZ.
• Squawkers – This speaker drive populates the mid range of human hearing or the “squawks” range. This typically happens from the 300 HZ to the 5,999 HZ range.
• Subwoofers – The lower end of the human audio spectrum is handled by this drive. The sounds produced by this type of speaker output, typically span from 20 HZ to around 300.
There are other, less popular types of drives as well, which include the woofer that are designed to produce even lower tones and the super tweeter that is meant to produce sounds from the opposite end of the spectrum.
All in all, the speaker has revolutionized the human audio experience. Today’s speakers have changed and transformed in ways that we would never imagine from the first speakers that were invented. We have miniature versions of these in our phones, more powerful ones in our televisions, and there are even speakers in some appliances like refrigerators and microwaves. In what ways will audio technology advance in the next century?