Basic Functioning System of a Loud Speaker

• The design of a speaker is the same regardless of its size or intended use. The basic components of a loud speaker include a speaker (sometimes referred to as a driver), a metal coil and a magnet. The coil is positioned between the driver and the magnet and is connected to both. An electrical signal is sent to the coil by alternating current. The magnetic properties affecting the metal in the coil and the magnet itself cause the coil to push and pull against the force of the magnet as the current runs through it. The action and reaction moves the speaker cone inside the speaker frame, which in turn creates sound wave.
  
  

Frequency Characteristics

• The static nature of the position of the speaker cone coupled with the mobility of the way in which it is mounted in its frame results in what is known as a free cone resonant frequency. This frequency is the median frequency within the possible range of frequencies that can be created by moving the cone. This aspect is important in loud speaker design. The acoustic reactions that take place within the enclosure must be calculated to minimize the median frequency response in order to avoid distortion of the sound.
  
  

Signal Source Influence

• The volume and timbre of the sound waves produced in a loud speaker enclosure are influenced by the characteristics of the signal sent to the coil. The source of the signal, such as a recorded music medium or a live instrument or voice, will affect the frequencies that are part of the electric current sent to the speaker. This source signal is controlled by the physics of its impedance (resistance to) the flow of the current. Audio signals generated by sound devices, such as stereo amplifiers and disc drives, generally have a low resistance to the current. Amplified voices and musical instruments have a higher impedance, and this difference in resistance factors creates different frequencies and waveforms.
  
  

Controlling Frequencies

• A loud speaker is often required to handle numerous frequencies, especially those speaker systems designed for live music venues and movie theaters. This amalgam of sound waves will cause distortion and other acoustic anomalies within the enclosure unless a method of controlling the frequencies is designed into the enclosure. The component most often used is known as a crossover circuit, a wiring system that captures and alters the source signal in order to separate the frequency ranges. Multiple driver types are required when a crossover circuit is employed in a loud speaker. These types are identified as tweeters (high frequency), mid-range drivers (median frequency) and woofers (low frequency), otherwise known as bass speakers.
  
  

Amplification

• The term "loud speaker" connotes the intended use of the enclosure. These speakers are meant to project sound at high volumes in order to fill large areas, such as concert halls and theaters. This requires the use of a high-powered amplifier to push the signal hard enough to move the larger magnets characteristic of loud speaker designs. These amplified signals create a wide range of frequencies that vibrate at a strong and other rapid pace, which in turn creates large and active sound waves. These elements are then passed through the coil and move the speaker cone to replicate both the frequency and the strength of the source signal.