Design And Construction Of 4-Way Channel Audio Mixer With Public Address System

This work is on a four channel audio mixer with public addressing system. This system does the work of combining (for audio selection) and modifying audio signals (for public addressing). Audio mixers are also called mixing consoles and soundboards. Mixers are most often used by recording studios but are also typically used in live situations by live sound engineers.

The aim of this work is to design and construct a 4-channel mixer which can accept four different audio input at the same time and mix their different tracks by changing their volume levels, adding effects and changing the timbre of each instrument on the tracks with public addressing system.

TABLE OF CONTENTS

COVER PAGE

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWELDGEMENT

ABSTRACT

CHAPTER ONE

1.0    INTRODUCTION

1.1    BACKGROUND OF THE PROJECT

• PROBLEM STATEMENT
• AIM AND OBJECTIVE OF THE PROJECT
• LIMITATION AND SCOPE OF PROJECT
• APPLICATION OF THE PROJECT
• LIMITATION OF THE STUDY
• SIGNIFICANCE OF THE STUDY
• RESEARCH METHODOLOGY
• PROJECT ORGANISATION

CHAPTER TWO

LITERATURE REVIEW

• INTRODUCTION
• HISTORICAL BACKGROUND OF THE STUDY
• THEORIES CONCEPT RELEVANT TO THE RESEARCH
• OVERVIEW OF PUBLIC ADDRESSING SYSTEM
• HISTORICAL BACKGROUND OF PUBLIC ADDRESSING SYSTEM
• DIFFERENT TYPES PUBIC ADDRESSING SYSTEM

CHAPTER THREE

METHODOLOGY

• INTRODUCTION
• BLOCK DIAGRAM
• SYSTEM CIRCUIT DIAGRAM
• EXPLANATION OF THE VARIOUS COMPONENTS IN THE PROJECT

CHAPTER FOUR

4.0   TESTING AND RESULTS

• INTRODUCTION
• CONSTRUCTION OF THE PROJECT
• TEST RESULT OF TESTS

CHAPTER FIVE

• CONCLUSION
• PROBLEM ENCOUNTERED
• RECOMMENDATION
• REFERENCES

 CHAPTER ONE

1.0                                                        INTRODUCTION

1.1                               BACKGROUND OF THE STUDY PROJECT

Audio mixer is an electronic device for combining, routing, and changing the level, timbre and/or dynamics of audio signals. A mixer can mix analog or digital signals, depending on the type of mixer. The modified signals (voltages or digital samples) are summed to produce the combined output signals.

Mixing mixers are used in many applications, including recording studios, public address systems, sound reinforcement systems, broadcasting, television, and film post-production. An example of a simple application would be to enable the signals that originated from two separate microphones to be heard through one set of speakers simultaneously. When used for live performances, the signal produced by the mixer will usually be sent directly to an amplifier, unless that particular mixer is “powered” or it is being connected to powered speakers. Among the highest quality bootleg recordings of live performances are the so-called soundboard recordings that are sourced from this mixer output to the speakers.

Prior to the emergence of digital audio workstations (DAWs), the process of mixing used to be carried out on a mixing console. Currently, more and more engineers and independent artists are using a personal computer for the process. Mixing consoles still play a large part in the recording process. They are often used in conjunction with a DAW, although the DAW may only be used as a multitrack recorder and for editing or sequencing, with the actual mixing being performed on the mixer. This device has an inbuilt public addressing system which is for public address; it has an estimated power rating of 20watts.

1.2                                          STATEMENT OF THE PROBLEM

In music industry, selection of different audio input to produce one output is always a problem in that it involves much labour. Mixers allow for precise tuning of microphone inputs and speaker outputs. The result is clearer sound, and more volume from the sound system before feedback occurs whilst the public addressing system is used in overcoming communication problems that usually occur in areas where it is hard to find a device for making important announcements or speeches so that everyone can listen precisely to what the speaker is talking about. This simple project may also be used by lecturers in lecture halls to bridge communication gap between the lecturers and student in a lecture, as shouting during lectures may be very exhausting.

1.3                                          RESEARCH AIM AND OBJECTIVE

The main aim of this work is to design an audio device which have and can accept four different audio inputs then with only one output with an inbuilt public addressing system. And the level of each audio input is controlled with potentiometer. The objectives are:

1. To have a public addressing system
2. To accept four different audio input to give out one output

• is to construct an electronic sound amplification and distribution device with a microphone, amplifier and loudspeakers

1.4                                          LIMITATION AND SCOPE OF PROJECT

This device was built using lm381 and lm386 are operational amplifier. Each of the amplifiers of lm381 is completely independent, with individual internal power supply decoupler-regulator, providing 120 dB supply rejection and 60 dB channel separation. Other outstanding features include high gain (112 dB), large output voltage swing (VCC b 2V) p-p, and wide power bandwidth (75 kHz, 20 Vp-p). High gain op amp combines up to four individually controlled input signals. This system is for audio selection and public address; it has an estimated power rating of 20watts. For power supplies, it uses a 220/12Vac transformer for the amplifier and loudspeaker units. It has a power On/Off button with volume control.

1.5                                          APPLICATION OF THE PROJECT

This system can use in places such as:

• school auditoriums,
• churches, and small bars.
• PA systems with many speakers are widely used to make announcements in public, institutional and commercial buildings and locations.

1.6                                                        LIMITATION OF THE STUDY

As we all know that no human effort to achieve a set of goals goes without difficulties, certain constraints were encountered in the course of carrying out this project and they are as follows:-

1. Difficulty in information collection: I found it too difficult in laying hands of useful information regarding this work and this course me to visit different libraries and internet for solution.
2. Difficulty in parts gathering: I found it too difficult when gathering electronics parts used for the prototype.

• Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).

1. Time Constraint: The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work.

1.5                                                      SIGNIFICANCE OF THE STUDY

This research work will throw more light on audio mixing and public addressing techniques. This study will also be designed to be of immense benefit to all the users of audio mixer and public addressing system.

It will also serve as a guide to whoever that wants to purchase audio mixer and public addressing system.

1.6                                             RESEARCH METHODOLOGY

In the course of carrying this study, numerous sources were used which most of them are by visiting libraries, consulting journal and news papers and online research which Google was the major source that was used.

1.7                                     PROJECT ORGANISATION

The work is organized as follows: chapter one discuses the introductory part of the work, chapter two presents the literature review of the study, chapter three describes the methods applied, chapter four discusses the results of the work, chapter five summarizes the research outcomes and the recommendations.