Design And Construction Of A 2-Channel Audio Mixer

ABSTRACT

An audio mixer is an electronic device for combining, and modifying audio signals. The modified audio signals are summed to produce some combined output signals.. A mixer is an electronic console that is used to mix different recorded tracks by changing their volume levels, adding effects and changing the timbre of each instrument on the tracks. 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.

In this work, an analog audio mixer using common electronics components, such as resistors, capacitors, potentiates and operational amplifiers (Op-Amps).

The aim of this work is to design and construct a 2-channel mixer which can accept two 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.

TABLE OF CONTENTS

TITLE PAGE

APPROVAL PAGE

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

TABLE OF CONTENT

CHAPTER ONE

• INTRODUCTION

1.1      AIM/OBJECTIVE OF THE PROJECT

1.2      SIGNIFICANCE OF THE PROJECT

1.3      APPLICATION OF THE PROJECT

1.4      PURPOSE OF THE PROJECT

1.5      SCOPE OF THE PROJECT

1.6      PROBLEM OF THE PROJECT

1.7      LIMITATION OF THE PROJECT

1.8      PROJECT ORGANIZATION

CHAPTER TWO

2.0 LITERATURE REVIEW

2.1      HISTORICAL BACKGROUND OF AN AUDIO MIXER

2.2      REVIEW OF AUDIO MIXING

2.3      REVIEW OF MIXERS

2.4      REVIEW OF TYPES OF MIXERS

2.5      FEATURES OF MIXERS

CHAPTER THREE

CONSTRUCTION METHODOLOGY

3.1 BLOCK DIAGRAM OF THE SYSTEM

3.2 CIRCUIT DIAGRAM

3.3 CIRCUIT DESCRIPTION

3.4 SYSTEM OPERATION

3.5 COMPONENTS LIST

3.6 12V REGULATED POWER SUPPLY

3.7 DESCRIPTION OF MAJOR COMPONENTS USED

CHAPTER FOUR

4.0 RESULT ANALYSIS

4.1 CONSTRUCTION PROCEDURE AND TESTING

4.2 ASSEMBLING OF SECTIONS

4.3 CONSTRUCTION OF THE CASING

4.4 ECONOMIC OF THE PROJECT

4.5 PROJECT VIABILITY

4.6 PROJECT RELIABILITY

4.7 PROJECT MAINTAINABILITY

4.8 PROJECT EVALUATION

4.9 TESTING, TROUBLESHOOTING AND REMEDY

CHAPTER FIVE

CONCLUSIONS

RECOMMENDATION

REFERENCES

CHAPTER ONE

1.0                                                        INTRODUCTION

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.

1.1                                             OBJECTIVE OF THE PROJECT

The objective of this work is to design an audio device which have and can accept two different audio inputs then with only one output. And the level of each audio input is controlled with potentiometer.

1.2                                              PURPOSE OF THE PROJECT

The purpose of work is to takes two audio signals, merges them together and provides one output signals.

1.3                          SIGNIFICANCE OF THE PROJECT

The role of a music producer is not necessarily a technical one, with the physical aspects of recording being assumed by the audio engineer, and so producers often leave the similarly technical mixing process to a specialist audio mixer. Even producers with a technical background may prefer that a mixer comes in to take care of the final stage of the production process.

Audio mixing is done in studios as part of creating an album or single. The mixing stage often follows a multitrack recording. The process is generally carried out by a mixing engineer, though sometimes it is the musical producer, or even the artist, who mixes the recorded material. After mixing, a mastering engineer prepares the final product for reproduction on a CD, for radio, or otherwise.

1.4                                                 SCOPE OF THE PROJECT

This device was built using lm381 operational amplifier. Each of the two 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

1.5                                         APPLICATIONS OF THE PROJECT

Public address systems use a mixing console to set microphones to an appropriate level, and can add in recorded sounds into the mix. A major requirement is to minimize audio feedback.

Most bands use a mixing console to combine musical instruments and vocals.

Radio broadcasts use a mixing desk to select audio from different sources, such as CD players, telephones, remote feeds, or prerecorded advertisements. These consoles, often referred to as “air-boards” are apt to have many fewer controls than mixers designed for live or studio production mixing, dropping pan/balance, EQ, and multi-bus monitoring/aux feed knobs in favor of cue and output bus selectors, since, in a radio studio, nearly all sources are either prerecorded or pre-adjusted.

Noise music musicians may create feedback loops within mixers, creating an instrument known as a no-input mixer. The tones generated from a no-input mixer are created by connecting an output of the mixer into an input channel and manipulating the pitch with the mixer’s dials.

Other places audio mixer have greater application include: including recording studios, public address systems, sound reinforcement systems, nightclubs, broadcasting, television, and film post-production. A typical, simple application combines signals from microphones on stage into an amplifier that drives one set of loudspeakers for the audience and also in a DJ mixer.

1.6                               PROBLEM OF THE PROJECT

Noise. This device tends to add some random noise to the signals passing through them, hence degrading the SNR (signal to noise ratio). This, in turn, limits the accuracy of any measurement.

1.7                            LIMITATION OF THE PROJECT

This audio device can only accept two different audio input to give a single audio output.

1.8                          PROJECT WORK ORGANIZATION

The various stages involved in the development of this project have been properly put into five chapters to enhance comprehensive and concise reading. In this project thesis, the project is organized sequentially as follows:

Chapter one of this work is on the introduction to an audio mixer. In this chapter, the background, significance, purpose, problem, limitation objective and application of an audio mixer were discussed.

Chapter two is on literature review of an audio mixer. In this chapter, all the literature pertaining to this work was reviewed.

Chapter three is on design methodology. In this chapter all the method involved during the design and construction were discussed.

Chapter four is on testing analysis. All testing that result accurate functionality was analyzed.

Chapter five is on conclusion, recommendation and references.