How Amplifiers Work ?
Mention the word “amplifier” to most people and they will think of a specific unit that is used to make electric guitars sound louder. A few people might know about amplifiers for other purposes, such as in a home stereo system. But there are many different kinds of amplifiers in use outside the world of music. For example, if you listen to music, watch a video with sound or view a Web site with audio and video you will be listening to sounds that are made louder or softer by an amplifier in your computer.
Televisions, CD and DVD players and car stereos all use amplifiers too. In fact, anywhere you hear sound that comes from a speaker there is an amplifier behind the scenes doing the work. Sound is produced and is heard by our ears because of vibrations or sound waves that move through the air. Human and animal ears detect the waves in the air around them. When these vibrations and fluctuations in the atmosphere around us strike the ear drum they are eventually converted into signals the brain can interpret.
What does this have to do with amplifiers? Sound waves from a speaker are caused by the cone of that speaker moving in and out in response to signals from the source. For example, the diaphragm inside the mike moves back and forth when you speak into a microphone. There are small vibrations that can’t be heard unless they are enhanced (amplified) by equipment further along in the system. The diaphragm movement in the microphone is converted into electrical signals that are representative of the sound wave movement.
The electrical signal from the microphone is small because the diaphragm movement is small. It’s necessary for the signal to be stronger so that it can be heard. The amplifier boosts the signal so that it is strong enough to move the speaker cone back and forth, making the sound waves of the voice large enough to be heard in the room. The same method applies to guitar amplifiers in that the signal from the instrument is made stronger so that the speaker pushes out larger waves of sound.
In situations where the original sound is recorded directly it may not be necessary to amplify the signal much, if at all. But when the recorded sound is played for listening in the home, for example, the amplifier in a CD player boosts the signal so that it is strong enough to make the speakers work. The larger sound waves/vibrations can then be picked up by our ears.
One key to understanding the task of an amplifier is that the signal from the source (microphone, instrument etc.) is changed so much that the output signal is distinctly different from the input signal. In most cases, the input signal is boosted by a pre-amplifier and this stronger signal is then used by the power amplifier. The electronic details for amplification are another story altogether.
Category: Technology