CONSTRUCTION OF AUDIO AMPLIFIER FOR EVENT

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ABSTRACT

This work is tilted construction of how audio amplifier for event. 60watt audio amplifier is a device for increasing the audio power of signal by use of an external energy source. It is constructed to meet up with the amplifier certain demand in home, offices, industries and especially in music industries. 60watt audio amplifier, amplifier low power audio signals (signals composed primary of frequencies between 20-20000hz, the human range of hearing) to a level suitable for driving loudspeaker and input signal to an audio amplifier may measure only a few be tens, hundreds or thousands of watts, this devices is construct to deliver appreciable, 60w power to the load. Audio power amplifiers may be called upon to supply power ranging from a few watts in an audio amplifier to many hundreds or thousands of watts to a load (speaker). In audio to the amplifier by a loudspeaker, and the function is to maximize the power delivered to the load over a wide range of frequencies. 60watts amplifier when constructed can produce up to 80 watt (4) of audio signal. It can be used to amplify the sound system that requires increased audio. This amplifier when produced in large or commercial quality according to purpose will create job opportunity provide indigenous electronics technology industry and it will contributes to economic growth of the country.

 

CHAPTER ONE

INTRODUCTION

1.1   BACKGROUND OF THE STUDY

An audio amplifier is an electronic amplifier that amplifies low-power audio signal (signal composed primarily of frequencies between 20-20,000 Hz the human range of hearing) to a level suitable for driving loud speakers; it is the final electronic stage in a typical audio play back chain. While the input signal to an audio amplifier may measure only a few hundred micro watts, its output may be tens of hundreds micro watts for a home system or thousands of tens of thousands watts for a concert sound reinforcement system.

The word audio means “sound signal” amplifier literally means “increase” therefore audio amplifier is an electronic amplifier which means “sound increase”.

The preceding stages in such a chain are low power audio amplifier which perform task like pre-amplification, equalization, tone control, mixing/effects or audio sources like record players, CD players, and cassette players.

Most audio amplifiers require these low-level inputs to adhere to time levels.

DESIGN PARAMETERS

Key design parameters for audio amplifier are frequency response, gain, noise and distortion.

These are interdependent, increasing gain often head to undesirable increases in noise and distortion, while negative feedback actually reduces the gain, it also reduce distortions. Most audio amplifiers are linear amplifiers operating in class AB.

FITERS AND PREAMPLIFIERS

Since modern digital devices, including CD and DVD players, radio receivers, and tape decks already provide a “flat” signal at line level, the preamplifier is not needed other than as a volume control and source selection.

One alternative to a separate preamplifier is to simply use passive volume and switching controls, sometimes integrated into a power amplifier to form an integrated amplifier. FURTHER DEVELOPMENTS IN AMPLIFIER

For some years following the introduction of solid state amplifiers, their perceived sound did not have the excellent audio quality of the best value amplifiers. This led audiophiles to believe that value sound had an intrinsic quality due to the vacuum tube technology itself.

In 1972, Matti Otala demonstrated the origin of a previously demonstrated the origin of a previously unobserved form of distortion transient. Intermediation distortion (TM) also called slew rate distortion TIM did not appear at steady state sine tone measurements, helping to hide it from engineers prior to 1972.

Problems with TIM distortion stem from reduced open loop frequency response of solid state amplifiers. Further work of Otala and other authors found the solution for TIM distortion including increasing slew rate, decreasing preamplifier frequency bandwidth, and the insertion of a lag compensation circuit in the input stage of the amplifier. In high quality modern amplifiers the open loop response is at least 20 Khz, canceling TIM distortion.

However, TIM distortion is still present in most low price home quality amplifiers.

The next step was the Baxandall theorem, created by peter Baxandall in England. This theorem introduced the concept of comparing the ratio between the input distortion and the output distortion of an audio amplifier. This new idea helped audio engineers to better evaluate.

The distortion processes within an audio amplifier.

However, audio amplifiers are of great important in home, bar and commercial areas today. In all musical instruments amplification of signals is needed.

Other electronic gadgets that utilized waves and signals also need amplification.

Therefore, the important for audio amplification has been of greater increase, since most signals like audios are employed at high frequency and at high pitch. A guitar amplifier is an example of audio amplifier that amplifiers the electrical signal of an electric so that it will produce sound through a loud speaker.

1.2   AIM

To construct a 60w audio amplifier system.

1.3   PURPOSE OF THE STUDY

  • Construction of a 60watts audio amplifier for event.
  • To construct an audio amplifier which could make a small signal to be bigger without making any other changes in it when used.

1.4   SCOPE OF THE STUDY

The study is limited to the construction and the used of an event audio amplifier to 60watts.

1.5   LIMITATION OF THE STUDY

In the course of carrying out this project work, several problems were encountered such as;

  1. a) Source of finance
  2. b) Source for material for construction
  3. c) Lack of technical know-how

Moreover, in respective of the problems encountered, the construction of the 60 watts audio amplifier was successfully carried out or done.

1.6   DEFINITION OF TERMS

  1. Transistor: This is a device manufactured from a semi-conductor in a solid station. It operate depends upon the flow of electric charge carries within the solid. Transistor is capable of amplification and mostly, it is a respected devices, it is similar to a vacuum triode the transistor is a current controlling devices.
  2. Diode: A semi-conductor material which is the joining of A p-type material with an N-type to form a simple semi-conductor. The term diode explains that diode has two electrode devices. A semi conductor diode is simply a P-N junction with a connecting heads or terminal on two sides of the P-N junction. Diode is a unidirectional device which permits easy flow current in one direction and retain its current in another direction.
  3. Linearity: The behaviour of an amplifier in which the input signal strength varies in direct proportion to the output signal strength.
  4. Signal: Signal are input received whose amplifier is to be amplified or increased.
  5. Distortion: The alteration in the waveform of an audio signal.
  6. Overdrive: a situation in which an amplifier exhibits linearity under normal condition, but becomes non linear when the input signal is too strong.
  7. P-N Junction: This is a junction in an electronic device farmed by crystals. A germanium and a penlatavalent formation. Therefore, P-N unction is also called crystal diode, in electronic technology, because it is grown and of crystal. It means the positive (Hole) and negative (electron) junction.
  8. Biasing: The process of applying dick across terminals of a transistor.
  9. CE: Collector Emitter, CC:  Collector Current
  10. Capacitor: This is an electronic component that stores charges.
  11. Amplifier: An appliance or circuit that increase the strength of a weak electrical signal without changing the other characteristics of the signal.
  12. Audio: It refers to sound, or electrical representation of sound.

 

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