The purpose of using an amplifier is to take an input signal, and then to increase its margin. Amplifiers are used in almost all types of electronic devices and is designed to perform a large number of many functions. There are many different types of amplifiers have been built in consideration is clearly a specific purpose. For a radio transmitter has a built RF amplifier, amplifies the signal. Most audio amplifier Here we will discuss has been specifically designed to drive speakers.

The purpose of using line array power amplifier, is to take input signal from source device and make them suitable enough to drive loudspeakers. The difference between signal at input and that at output is only signal amplitude.

Moderate power rating plays a very crucial role for amplifiers if they are operated under adverse power ratings. The output signal of amplifiers have some unwanted components which are not present in input signal these are called distortions. There are many distortion types; out of which common types are harmonic distortion and inter modulation distortion.

Input Sensitivity: It is the signal level which is required to get full power at amplifier's output. It would be useful if all amplifiers ever had gain; regardless of the power applied to it. Sensitivity varies widely, and ranges from 500mV up to 1.5V or more.

Total Harmonic Distortion: It is the measure of distortion of input signal, which keeps on adding many additional signal frequencies to the output which are not actually present in input signal. It is measured as a percentage, and ranges from 0.001% to 0.1% that too for hi-fi amplifiers. An ideal power amplifier should not have any distortion.

Transient Inter modulation Distortion: It is known as slew induced distortion, it occurs whenever the input signal changes so rapidly that output cannot keep pace with it.

Crossover Distortion: This distortion is caused by power output devices in a push-pull amplifier that operate in Class-AB. It does occur in valve and solid state designs, and is usually caused when devices turn suddenly off and other ones take over the half waveform.

Frequency Response: It is the amount of frequency versus the amplitude distortion in amplifier. A perfect amplifier simply amplifies all of the signals equally. An amplifier needs response of about 5Hz to 50kHz in order to ensure that all audible signals cater for minimal modification.

Phase Response: This indicates the time, before the signal reaches the output is delayed, based on the amount of the input signal frequency. In absolute phase change is inaudible amplifier system, but are generally considered undesirable fidelity news. Since it is not difficult to ensure phase linearity, this is not the general design issues, in addition to the valve amplifier.

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