12 CHANNEL AUDIO CONSOLE
ZURAIMI JOHARl
Universiti Malaysia Sarawak
2000
P. KHIOMAT MAKLUMAT
12 CHANNEL AUDIO CONSOLE
ZURAIMI JOHARI
Tesis Dikemukakan Kepada
Fakulti Kejuruteraan, Universiti Malaysia Sarawak Sebagai Memenuhi Sebahagian daripada Syarat Penganugerahan Sarjana Muda Kejuruteraan
Dengan Kepujian (Kejuruteraan Elektronik dan Telekomunikasi) 1-999/2000
80rang .)enycrahan Tesis Universiti Malaysia Sarawak
R13a BORANG PENYERAHAN TESIS
Judul : 12 Channel Audio Console
SESI PENGAJIAN: 19991200 Saya ZURAIMI JOHARI
(HURUF BESAR)
mengaku membenarkan tesis ini disimpan di Pusat Khidmat Maldumat Akademik, Universiti Malaysia Sarawak dengan syarat-syarat kegunaan seperti berikut:
I. Hakmilik kertas projek adalah di bawah nama penulis melainkan penu1isan sebagai projek bersama dan dibiayai oleh UNIMAS, hakmiliknya adalah kepunyaan UNIMAS.
2. Naskhah salman di dalam bentuk kertas atau mikro hanya bolch dibu8t dengan kebenaran bertulis daripada penulis.
3. Pusat Khidmat Maklwnat Akademik, UNIMAS dibenarkan membuat salinan untuk pengajian mereka.
4. Kertas projek hanYIl boleh diterbitkan dengan kebenaran penulis. Bayaran royalti adalah mengikut kadar yang diperscrujui kelak.
5. * Saya membenarlcan/tidak membenarkan Perpustakaan membuat salinan kertas projek ini sebagai bahan pertukaran di antara institusi pengajian tinggi.
6.
*.
Sila tandakan ( 3 )c:::=:JSULIT (Mengandungi maldumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972).
c=J
TERHAD (Mengandungi maldumat TERHAD yang telah ditentukan oleh organisasil badan di mana penyelidikan dijalanka.n).c=J
TIDAK TERHADDisahkan oleh
(TANDATANGAN PENULIS) (TANDATANGAN PENYELIA)
Alamat tetap: 155, Kampung Segedup, Jalan
Satu K.1wa, 93250, Kuching, Sarawak Encik Al-Khalid Othman
Nama Penyelia
Tarikh: Tarikh:
CATATAN • Po.mg yang tldak berkenaan.
Jika Kertas Projek ini SULlT atau TERHAD. sila Iampirkan surat daripada plhak berku.asa/
orpnlsasl berkenaan dengan menyertakan sekali tempoh kerta~ projek. Ini perlu dlkeJa..kan sebagal SULIT atau TERHAD.
Dedicated to my beloved family
iii
ACKNOWLEGMENTS
First of all, special thanks to the Dean of Faculty of Electronics and Telecommunications Engineering, Prof Madya Dr. Mohamad Kadim Suadi and to my supervisor, Mr. AI-Khalid for giving me support, ideas and motivation in accomplishing the objectives of this thesis project.
Appreciation is owned to the lecturers, the tutors, colleagues and especially to Encik Wan Abu Bakar who had given motivations, cooperation and helped me to finish this thesis at the Faculty of Electronics and Telecommunications Engineering of UNIMAS. Last but not least, to my beloved parents and my family for giving encouragement to me throughout the years.
IV
----.----~---~
ABSTRAK
Pada zaman sekarang, sistem audio memainkan peranan yang penting daJam menghasilkan bunyi yang lebih bennutu dan berkualiti bagi memberi kepuasan kepada para pendengar. Terdapat pelbagai jenis sistem audio tetapi tesis ini lebih banyak menitikberat terhadap sistem audio console. Sistem audio console amat jarang didengar tetapi peranannya amat penting dan banyak digunakan dalam bidang penyiaran. Tesis ini akan membincangkan dalam merekabentuk. sebuah sistem audio console, komponen yang digunakan serta masalah yang dihadapi. Beberapa cadangan serta kesimpulan juga disertakan diakhir laporan tesis ini.
v
ABSTRACK
Nowadays, audio system plays an important role in producing good and better quality sounds that satisfy the listeners. There are several types of audio system but this thesis is more concern about the audio console system. We seldom hear about audio console system but its role is very important and is widely used especially in broadcasting area. This thesis discussed the architecture and design of the audio console as well as the components that being used and the problem faced. Some conclusion and recommendation are included at the end of this thesis report.
VI
Pu t Khidrmt MaJcl rAhd UNIVERSm MALAY IA SARAW... K
CONTANTS
PAGE
DEDICATION
ACKNOWLEDGEMENT
ABSTRACT ii
CONTENT iv
LIST OF FIGURES v
CHAPTER 1: INTRODUCTION
1
1.1 Project Overview
1.2
Objective And Aims Of The Project 41.3
Outline Of Thesis 4CHAPTER 2: LITERATURE REVIEW 5
2.0
Description On Audio Console 52.1.1
Input Channel 52.1.2
Output Section 62.2
Audio Amplifier 62.2.1
Amplifier Coupling 62.2.2
Preamplifier 72.3
Controls 72.4
Tone Control 82.5
Operational Amplifier 10vu
2.5.
1
Differential Voltage Gain 102
.5.2 Transfer Characteristic 122.5.3
Frequency Response 122
.5.4 Slew Rate14
2.5.5
Input Impedance IS2.5.6 Output Impedance
15
2
.5.7 Inverting Input15
2
.5.8 Non-inverting Input16
2.6
Distortion16
2.6.1
Amplitude Distortion17
2.6.2
Hannonic Distortion17
2.6.3
Intennodulation Distortion17
2.6.4
Frequency Distortion18
2.7
Active Filter18
2.7.1
Low Pass Filter19
2.7.2
High Pass Filter19
2.7.3
Band Pass Filter20
2.7.4
Band Reject Filter20
2
.8 Power Supply22
2.8.1
Transfonner23
2.8.2
Rectifier24
2.9 Meter Level Indicator
26
2.9.1
Led Emitted Diode26
viii
3.0
HARDWARE DESIGN28
3.1 Introduction
28
3.2 Circuit Diagram
28
3.3 General Description LM358 30
3.4 General Description LM741 31
4.0
ANALYSIS AND TROUBLESHOOTING 324.1 Introduction 32
4.2 Process of Making 32
4.3 Analysis of Preamplifier Using LM358 33
4.3.1 Component for Preamplifier 34
4.3.2 Result on Preamplifier 35
4.4 Analysis of Auxiliary 38
4.4.1 Component for Auxiliary 39
4.4.2 Result on Auxiliary 39
4.5 Circuit Analysis on Tone Control 42
4.5.1 Component For Tone Control 43
4.5.2 Result On Tone Control 43
4.6 Circuit Analysis on LM741 46
4.7 Circuit Analysis on Meter Level Indicator 47
4.7.1 Component for graphic bar 48
4.8 Circuit Analysis on Power Supply 48
4.8.1 Component for power supply 49
4.8.2 Result On Power Supply 49
IX
4.9 Troublcshooti ng 53
4.9.1 Types of Problems 53
4.10.1 Simulation 54
5.0 CONCLUSIONS AND FUTHER WORKS 60
REFERENCE 62
x
LIST OF FIG II RE
Figure 1.1: Block diagram from channel input to main output of audio console
Figure 1.2: Diagram for function of audio console Figure 2.1.2: Block diagram for audio system
Figure 2.4.1: Bass tone control Figure 2.4.2: Treble tone control
Figure 2.5: Operational Amplifier Figure 2.4.2: Treble tone control Figure 2.5.1.2: Closed-loop mode
Figure 2.5.2: Transfer Characteristic for Vin vs Vout ofOp-Amp Figure 2.5.3: Voltage Gain Versus Frequency
Figure 2.5.7: Inverting Amplifier
Figure 2.5.8: Non-inverting Amplifier Figure 2.4: Several types of filter
Figure 2.5: Block diagram of power supply Figure 2.5.1 : Bridge rectifier
Figure 2.7: Several types of filter
Figure 3.2: Circuit design for audio console Figure 3.3: Connection Diagram for LM358
PAGE
3
3 6
9 9 10 11
11 12 14 16 16 21 22 25 21 29 30
xi
L
I
Figure 3.4: Connection Diagram for LM741C 3 I
Figure4.3: Preamplitier 33
Figure 4.3.2.1: Input signal being applied to preamptifier 35
Figure 4.3.2.2: Output of preamplifier 36
Figure 4.3 .2.3: Original input at preamplifier 36 Figure 4.3.2.4: Original output signal at preamplifier 37 Figure 4.4.2.1: Result from the end of potentiometer 40 Figure 4.4.2.2: Output from op-amp at high level gain 41 Figure4.4.2.3: Output from op-amp at low level gain 41
Figure 4.5: Bass and Treble 42
Figure 4.5.2.1: Treble boost 44
Figure4.5.2.2: Treble cut 44
Figure 4.5.2.3: Bass boost 45
Figure4.5.2.4: Bass cut 45
Figure 4.7: Graphic meter 47
Figure 4.8: Power Supply circuit design 48
Figure 4.8.2.1: Rectifier 50
Figure 4.8.2.2: Output at positive voltage 50
Figure 4.8.2.3: Output at negative voltage 51 Figure 4.8.2.4: Secondary filtering for negative voltage 51 Figure 4.8.2.5: Secondary filtering at positive voltage 52
Figure 4.l1.1: Input for preamplifier 55
Figure 4.11.2: At inverting input LM358 55
Figure 4.11.3: Output from preamplifier 56
XlI
I
Figure 4. I 1.4: Output tl>r LM74 I C 56 figure 4.11 .5: Inverting input at LM741 C 57
Figure 4.1 1.6: Output at LM74 ~C 57
figure 4. I 1.7: At bass boost 58
Figure 4.11.8: Bass cut 58
Figure 4. 11.9: Treble boost 59
Figure 4.11.10: Treble cut 59
XU I
CHAPTER 1
1.0 INTRODUCTION
Audio console is a toll for achieving a good and better quality of sound. It is
commonly been used for broadcasting and for recording such as Radio Televisyen Malaysia (RTM), Cats Radio, BMG and others production house for recording.
Audio console can adjust the volume, the tone and the master control for audio signal. This adjustment is needed due to the difference types of music such as
rock, pop, soul and others. By using the adjustment for control, distortion can be avoided or can be minimized.
1.1 Project Overview
The designing of an audio console is to distribute the input of audio signal such as microphone, compact disc players or cassette players to a common sound distribution system such as equalizer, power amplifier or speakers and the output
signal can be modified in tenns of volume or tone. Before distributing the audio signal to a common sound distribution system, the audio signal is mixed together in the audio console to get a better quality of sound and give satisfaction to the listener.
-
1,1
II
Audio console actually has some important similarities to a simple home stereo receiver. A stereo receiver can controls to set overall volume, the balance between len and right speakers and some tone controls to shape the overall sound. The audio console does many of the same things including changing levels and tone.
The most important difference between an audio console and a stereo system is that an audio console can control and combine or mix sounds from many different sources at once. Rather than simply choose between one sound and another, an audio console gives the option to can adjust and combine all variable of sound at the same time and produce a better quality of sound. But this adjustment can not be achieved by using home stereo system.
The audio console can be described as a traffic manager for all the individual audio signals by providing signal routing. The signal routing IS
depending to the person who controls the audio console and the type of music.
2
I
Len
Input channel
To
Fader Pan
Mix b s
Input channel
Right
Monitor selector
Main output
output R
fader Master selection
Figure 1.1.1: Block diagram from channel input to main output of audio console
Figure 1.1 .2: Diagram for function of audio console
3
1.2 Ob.iective and Aims Of The Project
The objectives for this project is to design and build an audio console which has 12 channels control, designing the power supply, and the meter level indicator. The aims of the project are to study the operation of the audio console and to investigate and identify the characteristic of the components being used.
1.3 Outline of Thesis
This thesis includes five chapters. In the chapter 1 of this thesis report consists of the project overviews and the description of an audio console. Chapter 2 discusses more on the literature review about the basic idea of designing an audio console. Chapter 3 is related to the process of designing the circuit and how the function of the components in the project. Chapter 4 is about the testing that has been done. Implementation of the concept and experiment is very important to achieve the project's mission. Chapter 5 is more concern about the problem that arises during constructing the project.
4
Pu t Khidm.1 Maklu I Ak milt UNIVER5lTI MALAYSiA ~AR AK
CHAPTER 2
1.0 Description for audio console
Audio console consists of two parts such as input section and output section. The input section is a part where the audio signal is connected to the audio console. Output section is more to how the audio that being process is distributed
1.1.1 Input Channel
The first control 10 signal change is input gain or sensitivity. The amplification of the input amplifier can be adjusted in decibels. Inputs are nonnally located between microphone and line. For the output level of microphone, the input gain is adj usted to raise the signal to a suitable line level up to 80dB. The amplification is used at the line position and the gain control for adjustment is either OdB for unity gain or
±
20dB. The tone control provide a boost and cut of around ± 12d.B. Over broad low frequency and high-frequency bands. [2]Input gain control is to sets the microphone or line input to match the level of incoming signal.
5
• Microphone/line switch is the connection between microphone and line input. Line input is can be playback of cassette, CD player or others equipment. [2]
2.1.2 Output Section
The two main output faders (left and right) control the overall level of the channel signals, which have been summed on the left and right mix buses. The outputs of the faders feed the main output connectors on the rear panel and an internal feed is taken from the main outputs to the monitor selector. [2]
Detector I Input
-" l 1
an d-.
Amplifier
Volume Preamplifier
and tone
..
control
r
1',;-
Driver amplifier
r
Speaker Power ...
... ~
amplifier
V'
Figure 2.1.2: Block diagram for audio system
2.2 AUDIO AMPLIFIER
In the world of audio system, the amplifier has much application.
Basically. amplifier is a device that can increase the power of signal. It receives a weak audio signal from the input source and provides a larger signal at the output.
6
Sometimes, output signal can be increased twice than the input sibrnal. The output wavefonn must have the same shape as the input wavefonn but ditTerent in amplitude ofthe wavetorm.
2.2.1 Amplifier Coupling
It is important to provide some method of coupling between amplifier stages that are connected cascade. When passing a signal from one stage to the next cascade chain, the proper condition can be met. The coupling circuit must not just couple the signal; it must match the impedance between the stages so that the maximum power transfer occurs when the impedance of the source and load are matched.
Capacitor coupling is to pass the signal from the input stage to the output stage without letting the dc voltage used to operate the input stage affect the bias of the output. The low frequency response of the circuit is partially dependent on the respective values of the resistance in the circuit and the coupling capacitor. [8]
2.2.2 PREAMPLIFIER
Preamplifiers provide the interface between low-level signals from microphones, phono pickups, and so on and the various signal-processing equipment ina sound system or a studio. [3]
Normally, the preamplifier is located near to the transmitting source and before the amplifier. This is because the preamplifier can select the low input
7
audio signal from sources and amplified the audio signal. This process is necessary so that the audio signals are in the size and can be fanned to drive to the power amplifier. The main purpose for using a preamplifier is to increase the signal Voltage.
2.3 Controls
With any audio system, it is necessary to provide an adjustment for the overall signal level. This adjustment is known as gain control or volume control.
The adjustment can let the listener to select the volume or tone depends on their interest in music. This control will be placed inside the preamplifier.
2.4 Tone Control
Nowadays, listeners are preferred to hear music with the best quality of sound by controlling the tone control. This can make the listener do not feel boring or getting tired and give satisfaction when their listen to the cassette, CD or radio.
The tone control can modify the frequency response of the system and detennined the degree of the roll off curve. It also can provide a stable gain for small signal, which have low input noise, provide little or no sensitivity to induce and no distortion. Tone can modify the tonal characteristic of the signal chain.
Tone control can be formed into treble and bass. Treble is used to adjust the high
frequency response of an audio amplifier. Meanwhile, bass is used to adjust the
8
low-frequency response. This adjustment IS important due to the variation of human ear. [2]
In audio systems, it has a tone control that feature boosting or cutting the volume of bass or treble frequencies. The practical tone-control circuit shown in Figure 2.2 features boost or cut of bass frequencies below 500Hz and of treble frequencies above 2kHz and ehminates attenuation. Refer to [8] for more information. Basic tone control can be seen in Figure 2.4.1. and Figure 2.4.2.
Yin
Boost i
Vout Cut
~
Figure 2.4.1: Bass
Yin
Vout
Figure 2.4.2: Treble tone control
9
2.5 OPJ4:RATIONAL AMPLIFIER
Operational amplifier is used to allow as a wide variety of audio and video applications. The basic schematic symbol for an op amp is shown in tigure 4.0. rt has the inverting and noninverting inputs labeled (-) and (+), respectively and has a single output. [4]
Inverting
input----i
Non-invertin input
Figure 2.5: Operational Amplifier
2.5.1 Differential Voltage Gain
The differential voltage gain is the amount of amplification given to voltage appearing between the input tenninals. In the case of the ideal op amp, the differential voltage gain is infinity. [4]
The gain may exceed 200,000 in the open-loop mode. In the open-loop mode there is no feedback from the output 0 the inputs as the voltage gain is
10
