How Do Audio Amplifiers Work?

What is an Amplifier?

If you've ever been to a rock concert, a movie theater or simply listened to music on your way to work, you've used an amplifier. Amplifiers can come in many forms. Everything from the tiny ear-buds you use with your MP3 player to the earth shaking surround sound systems in an IMAX theater are all amplifiers. Their main function is simply to take an audible sound (a voice, a sound effect, a musical instrument) and make it louder. Some amplifiers manipulate the sound it is reproducing. A guitar player may use his amplifier to add distortion or reverb to his guitar sound. Others may use equalization to add bass for a seat rattling movie experience. The bottom line though, amplifiers are all about volume.

Moving Air

The most important thing needed to amplify sound is air. The amplifier, or amp, takes an audio signal and vibrates the speaker inside. This vibration moves the air around the speaker. Your ear perceives this as audible sound. In fact, the human ear itself functions the same way. Your eardrum fluctuates with the vibrations it is receiving and send those signals to your brain as sound. The more power an amp has, the more air it can move and thus, create a louder sound. So, we know that amps need to move air to amplify audio signals. But how does it get the signal in the first place?

Power Surge

Amplifiers reproduce audio signals that it receives via an electrical signal. When you're speaking into a microphone, your voice is vibrating a tiny diaphragm inside. The microphone generates an electrical impulse that fluctuates with those vibrations and sends them through a cord into the amp. At this point, the amp increases the strength of that signal by passing it through tubes and/or transistors. The amount the signal is increased is based on the wattage of the amp and how large of a speaker you are trying to vibrate. The newly juiced up signal is now translated back into vibrations and emitted as audible sound through the speaker. It's important to know how much a speaker can take. If the signal output is too high for a given speaker, it can literally tear the speaker apart.