Introduction and Meaning:
Usually, an amplifier is any device that changes or affects change on the amplitude of any given signal. The relation of the input and the output of the amplifier (generally termed as the function of an input frequency) is known as the transfer function of an amplifier. The unit of the transfer function is known as the gain. In terms of audio appliances, an amplifier drives the loud speakers that are used in the PA systems to play music or magnify the human voice.
Amplifiers could be classified in terms of the input they are made to amplify, the appliance they are made to drive, the range of frequency of the signals, whether they manage to invert the signals or the kind of appliance used in the process of amplification.
Features and Uses of Power Amplifiers:
All power amplifiers have a particular power rating. The unit used for measuring power is called the watt. The power rating of any amplifier may be given for particular resistances. The unit for measuring resistance is called the ohm. The most commonly seen resistances are 8 ohm, 4 ohm and 2 ohm. In the yesteryears, power amplifiers used appliances called vacuum tubes. Tubes are very rarely used in amplifiers nowadays, especially by disc jockeys. Modern amplifiers, nowadays, use transistors.
An amplifiers’ chief function is to receive a comparatively weaker signal and turn it into a signal strong enough to drive a speaker. Generally, the power amplifier gets the required energy from AC wall outlets in they get plugged into. If one has a perfect amplifier (logically impossible) all the energy from the AC wall outlet would get converted into useful output. Many amplifiers have a number of extra features. Some amplifiers have features that can help us monitor the position of the amplifier in terms of load. This may be very useful in event of overload. These features vary from manufacturer to manufacturer. Some people believe that more the power rating of an amplifier the better it is. This is not the case. A well designed 200 watt per channel amplifier could be much better than a comparatively carelessly designed 500 watt per channel amplifier.