Amplifiers are everywhere. Mostly associated with musical instruments, amplifiers can also be found in your telephone, clock radio or even a hearing aid – basically anything that emits sound. The main purpose of any amplifier, big or small, is to raise the level or amplitude of an electronic signal so you can hear it…plain and simple. So how does it all work? Let’s take a look inside.
The starting point of any amp’s circuitry is the input. That’s where you plug in your microphone, guitar or any other source. From the input, the signal is carried through an electrically powered circuit and amplified. At the end of this signal path is the output where the enhanced sound enters speakers, headphones or another amplifier.
As you sing or play an instrument, sound waves are created by the vibrations. For example, when you pluck a guitar string, these vibrations are converted into a low voltage electrical current by microphones and electrical guitar pickups. A pre-amp then boosts the electrical current into a usable signal and can also enhance the best qualities of this signal, such as more bass or treble. This signal is still too weak to vibrate the cones of a speaker. That’s where a power amplifier comes in. It gives the signal enough energy to move the speaker cones and create the sound we hear. Sometimes the power amplifier is built into the speaker cabinet or it comes as a separate unit called a head. The head can be used to power one or more separate speaker cabinets. The most common options available today are P.A. and studio speakers with built-in power amps.
The amp you choose depends on what you want to use it for. There are many different kinds of amplifiers because there are many different types of sources. Guitars, drums, keyboards and vocals all generate a variety of sounds and there are amplifiers especially suited to each of those applications. P.A. systems can also be used to amplify drums, vocals or even other amplifiers.
An amplifier comes with a set of specifications which tell you how it performs. They include frequency response, noise, gain and power. Frequency response reveals the amp’s ability to handle high, low and midrange sounds. Signal-to-noise ratio tells you how much electric hiss the circuits will add to the sound you are amplifying. Gain is measured in decibels (dB) and relates to the amplifiers ability to increase the power of the signal. The power of the amp itself is measure in watts. This tells you how loud the sound can get before it becomes distorted.
You must also pay attention to the inputs and outputs on your amplifier. Inputs come in a variety of gain levels which relate to the source you want to amplify; microphone, instrument or even a cd player. It’s important to match the output with the correct speakers to avoid damaging them or the amplifier.
Basically, every audio amplifier is a system of different components that work together and depend on one another, just as you depend on the amp to deliver sound. Amps allow us to listen and be heard when we sing or play, making our lives better one decibel at a time.