Loudspeakers are critical to any audio system. From tweeter speakers to woofer speakers, loudspeakers are the components that provide movies, music, and sports with sounds that are often taken for granted.
Microphones convert sound into electrical impulses that can be recorded onto some form of storage media. Once captured and stored, it can be reproduced at a later time or place. Hearing recorded sound requires a playback device, an amplifier, and, most critically, a loudspeaker.
What Is a Loudspeaker?
A loudspeaker is a device that converts electrical signals into sound as the result of an electro-mechanical process.
Speakers typically incorporate the following construction:
A metal frame or basket, within which all the speaker components are placed.
A diaphragm that pushes air out through vibration. The vibration patterns reproduce the desired sound waves received by your ears. The diaphragm is often referred to as the cone. Although a vibrating cone is commonly used, there are some variations, which are discussed below.
An outer ring of rubber, foam, or other compatible material, referred to as a surround. Not be confused with surround sound or surround speakers, the surround holds the diaphragm in place while providing enough flexibility to vibrate. Additional support is provided by another structure, referred to as a spider. The spider makes sure that the vibrating speaker diaphragm and surround do not touch the outer metal frame.
A voice coil wrapped around an electromagnet is placed at the back of the diaphragm. The magnet or voice coil assembly provides the power to make the diaphragm vibrate according to the received electrical impulse patterns.
Cone speakers also have a little bulge that covers the area where the voice coil is attached to the diaphragm. This is referred to as the dust cap.
The speaker (also referred to as a speaker driver or driver) can now reproduce sound, but the story doesn't end there.
The speaker must be placed inside an enclosure so that it performs well and looks aesthetically pleasing. Most of the time, the enclosure is some type of wood box. Other materials, such as plastic and aluminum, are sometimes used. Instead of a box, speakers can come in other shapes, such as a flat panel or sphere.
Not all speakers use a cone to reproduce sound. Some speaker makers, such as Klipsch, use horns in addition to cone speakers. Other speaker makers, most notably Martin Logan, use electrostatic technology in speaker construction. Still others, such as Magnepan, use ribbon technology. There are also cases where the sound is reproduced by non-traditional methods.
Full-Range, Woofers, Tweeters, and Mid-Range Speakers
The simplest loudspeaker enclosure contains only one speaker, which reproduces all the frequencies sent to it. However, if the speaker is too small, it may only reproduce higher frequencies.
If it is medium-sized, it may reproduce the sound of a human voice and similar frequencies well and fall short in the high and low-frequency range. If the speaker is too large, it may do well with lower frequencies and, perhaps, mid-range frequencies, and may not do well with higher frequencies.
The solution is to optimize the frequency range that can be reproduced by having speakers of different sizes inside the same enclosure.
A woofer is a speaker that is sized and constructed so that it can reproduce low and mid-range frequencies. Woofers do most of the work in reproducing the frequencies you hear, such as voices, most musical instruments, and sound effects.
Depending on the size of the enclosure, a woofer can be as small as 4 inches in diameter or as large as 15 inches. Woofers with 6.5-inch to 8-inch diameters are common in floor standing speakers. Woofers with diameters in the 4-inch and 5-inch range are common in bookshelf speakers.