ABSTRACT

The project with construction of an audio mixer power amplifier with four output channels and about 250wattt amplification power, smaller size and lesser-heat generating device. It is meant to explore identify the possible solutions to much heat generations and unbalance output quality, despite the magnitude of the input signal. It will also solve problem of unbalance mixing of different audio signal encounter with most amplify system around. An audio mixer power amplifier is both tinny and easy to use and operate, especially, if the application does not require the equipment to operate within its design limit. The aim of this research work is to slow how easy this equipment can be used in a variety of applications involving different levels of audio signal mixing, public addressing system, audio amplification, audio signal rectification, filters and controls. It exposes the constructions of an inexpensive, simple and easy to use and reliable operational amplifier.

CHAPTER ONE

INTRODUCTION

1.1   BACKGROUND OF THE STUDY

        In the ancient days, electronic technology was not modifying in a simple form compare to the electronic technology. There was little or no global project on designing complex amplifying circuits that were simplified enough for the researcher at that time. To amplify a small or weak signal (sound) they use large physical medium.   

Generally, amplifier designing was a specialized task for professionals in the electronic world. An audio mixer power amplify       amplifier that amplifier is an electronic amplifier that amplifies low- power audio signal  (signal composed primarily of frequencies between 20-20,000Hz, then human rage of haring) to a level suitable for driving loudspeakers and is the final stage in typical audio playback chain. The proceeding stage in such a chain are low power audio amplifier which perform tasks like pre-amplification, equalization, two control, mixing/ effects, or audio sources like record player, and cassette players. Most audio power amplifier requires those low- level inputs to adhere line levels. While the inputs signal to an audio power amplifier may measure only a few hundred micro watts, its output may be tens, hundreds, or thousands of watts.

The first audio amplifier was made in 1906 by a man named Lee De Forest and come in the form of the triode vacuum tube. This particular mechanism evolved from the audio, which was developed by De Forest. Unlike the audio triode which has three elements, the audio only has two and did not amplify sound. Later on during the same year, the triode, a device with the capability of adjusting the movement of electrons from filament to a plate and thus modulating sound, was invented, it was vital in the invitation of the first AM radio.

After world war 11, there was a surging of technology because of the advancement developed during the war. The earliest kinds of audio amplifiers were made of vacuum tube or valves. An example of these is the Williamson amplifier, which was introduced in 1946. At the time, this particular device was considered cutting edge and produced higher quality sound compare to other amplifiers available at that time. The market for sound amplifiers was robust and the value type device can be owned at affordable rate by the 1960s, gramophones and television made value amplifier quit popular.

By the 1970s, valve technology was replaced by, the silicone transistors. Although valves not completely wiped out as evidenced by the popularity of the cathode ray tubes, which was used for amplifier applications, Silicon transistor became more and more present. Transistors amplifier sound by changing the voltage of audio input through the use of semi conductors. The reason for the preference of transistor over valves was that they were smaller and thus more energy efficient. In addition to these, they are also better at reducing distortion levels and were cheaper to make.

        Most audio amplifiers in use today are considered to be solid state transistors. An example of this is Bipolar function transistors, which has three element made out of semiconductor material. Another kind of amplifier used in recent years is the MOSFET (the metal oxide semiconductor filed effect transistor). Invented by Julius Edgar Warfield, it was first conceptualized in 1925 and has both digital and analog circuit application.

Although solid state amplifier offered convenience and efficiency, the skill could not produce the quality of those made of valves. In 1872, Matti Otala discovered the reason behind this; Inter-modulation distortion (TIM). This particular kind of distortion was cause by the fast increase of voltage in the audio output device. Further research remedies this problem and thus resulted in amplifier that cancel out the TIM.

Hence, “amplifier is an electronic device that amplifies, or increase weak signal or power of an input signal”.

AMPLIFIERS OF DIFFERENT TYPES, NAMELY:

v    Operational amplifier (op amp)

v    Power amplifier

v    Audio amplifier

v    Video amplifier transistor amplifier etc.

        Of these five amplifiers, the audio mixer power amplifier is the emphasis of research work. The equipment which is related 250W has other sub-amplifier circuit that makes up the whole audio mixer power amplifier, the pre- amplifier circuit, power circuit, tone CCT main amplifier, circuit audio amplifier, circuit and the mixer amplifier.

        Circuit this equipment can accept up to four channels different strength level of audio signal input mixers then to give one desire output.  Audio amplifier performs a function as a result of an integrated circuit (which is the Op-Amp) which plays vital role in an audio amplifier circuit as an amplifier.

        An integrated circuit (IC) which was introduced in 1958 is design through the incitement of components such as transistor, resistors, capacitors and diodes which are encapsulated together in silicon clip. ICS is one of wide range of types for low level amplifiers and pre amplifier low output or high output. IC’S works by receiving input from a pick up and delivering the output on loudspeakers. The elements in ICS are produced directly in clips of semi-conductor’s materials and they lie close together occupying out tiny values.

        New or customized ICS may be designed and fabricated for a specialized applications, although, this may increase the cost of the system. But as engineers, the cost of any component should not influence the construction of ideal equipment.

        This project will give an insight on the application of a mixer power amplifier. Its circuit design and the components used in constructing the equipment. The problems encountered in the operation and the solution for trouble shouting of each component in the audio mixer power amplifier will also be discussed in this study.