Ch 4.3 - Sound System

شهروالنيظام™

SOUND SYSTEMINTRODUCTION

Mono System

Surround System

Quad System

Stereo System


PUBLIC ADDRESS SYSTEM

Equipment maintenance

Sound system installation

Reinforcement equipment

Sound reinforcemant

Method of power distribution

PUBLIC ADDRESS SYSTEM


Sound : The perception of the dinamic convergence and

vacuum air pressure level in ear. Audio : Produce from sound to electronic Sound wave : Generate from vibration/ shake.

The air molecul near to the shaking source will shake too. Sound wave is produce when the molecul move reverse in position same with the shaking object.

Amplitud & strength of sound : The number of moving molecul described the strength of sound and this is called – sound amplitud ( measured in dB )

Acoustic pressure is measured in Sound Pressure Level.

Dinamic range : Range from silence sound level to a noisy sound level that can be heard.

Monaural : Sound from Headphones Monophonic : Sound from speaker.


0 Hz

20 Hz

20kHz

∞

Sound Pressure Level (SPL) –

SPL = 20 log Po/ 2 x 10⁻⁵ dB

* Po – Sound power level

2 x 10 ⁵ - Min. pressure of sound⁻

Human hearing level - 0 dB-SPL to 120 dB- SPL

( ear will start feel the pain)

The Biology of Ear :

• Divided to 2 area :

i. External – Directional sound area (sound calyx)

ii. Intermediate – Gegendang (reception of different type of

sound freq)

- Differentiate between human and the animal

Infrasound

Hearing band

(Sound Freq :

Ultrasound

100 Hz ~ 5kHz)


Mono system – Depand to one recording system and sound channel.

i.e. – telephone system (monaural system). Whereas, radio broadcasting and sound system at cinema (monophonic system).

Monaural : Sound from Headphones Monophonic : Sound from speaker. Info from mono system ≠ original info if the

audience concentrate. Because the microphone pick the sound signal from one point whilst audience can hear sound from two points.


• Stereo system – audio system that produce sound from 2 direction. • The good stereo system can produce sound illusion (position are fixed – cross the sound stage). In hi-fi system it is called stereo image. • User can separate and compare the sound o/p where the sound quality can be adjusted by considering the sound balance.


SISTEM QUAD• QUADRAPHONIC @ 4 audio speaker system.• To boost the stereo sound.• Better sound spreading compare to stereo sound system with 2 speaker. • Surround @ rear speaker – for environment

sound.• This system are used to compressed the audio

o/p. i.e Concert


Dolby Surround - New dimension of sound addition to

common stereo sound. - Using Dolby MP Matrix Encoder ~

encod 4 audio channel to 2 audio channel for stereo broadcasting programme.

SurroundSurround

L C R

Layout for stereophonic sound / Dolby Stereo


5.1 Channel System

This system have 5 channel - frequency range from 3Hz to 20 KHz for front, left and right, center, surround o/p and additional of LFE (Low Freq. Effect) Sub-Woofer - freq range from 3 Hz to 120 Hz.

Dolby Digital Encoder

Producer/Mixer Multi Channel Audio

L

C

R

Ls

Rs

Digital Media

Digital Bit Stream

A/V comp. with Dolby Digital decoder

L

C

R

Ls

Rs


When sampling the wave with an analog-to-digital converter, two variables need to be controlled :

The sampling rate - Controls how many samples are taken per second

The sampling precision - Controls how many different gradations (quantization levels) are possible when taking the sample


PUBLIC ADDRESS SYSTEM (SISTEM SIARAYA)Necessary for the user that is far away from the sound source. Basic requirement ; microphone, amplifier and speaker.

P.A. system divided to 2 level :- High level system - wide area i.e Mosque, stadium and useful for for place which is crowded with people - Low level system - narrow area i.e. meeting room and place

which have a few people only. Divided to 3 category :- A Category – Open area ~ audiens > 5000 B Category – Inside hall ~ audiens > 1000 C Category – Inside hall ~ audiens ≈ 500


PERALATAN SISTEM BUNYI MASJID

COLUMN SPEAKER

HORN SPEAKER


The effeciency of P.A. systemDepend to :-i. Sound strength – sound that have enough strength to be heard at all position in one area. ii. Sound quality – The clear sound condition. Low freq need to be reduce @ adjusted in a closeted place. Also reduce the sound transmission to the mic to avoid sound interrupt. iii. Sound balance – To makesure sound not interrupted to any other influence. The sensitivity and tone control need to be test from every input area before the function start. iv. Direction effect – To makesure audience received suitable sound direction & not from multiple direction. Speaker should be positioned at correct angle and the distance between mic and speaker ≈ 7 meter.


MIC

Main ClusterFill System

Cover by fill speaker Cover by main cluster

Rear Fill System

Cover by rear fill system

MIC

Main Cluster

Fill System

Balcony


3 procedure on selecting and setting the sound system

• Determine the function and the reason why the audio system and the installation equipment is used.

• Before start the equipment installation for audio system, detail planning is needed to understand the specification & cost estimation.

• Others factor that relates is as below :- Study the sound condition in the area.Audio system selection and the determine the position of installation.Draw the block diagram of the system, circuit diagram, arrangement & specification.Wiring & installation for the audio system equipment have been selected.


Additional equipment in P.A.

1. Microphone - Convert acoustic energy to

electric energy

- Able to convert in same value ---

sound wave electric sound ----

in wide range - Electrostatic, moving coil

& ribbon - Need good ratio between

sound & noise.


2. Speaker - Mono speaker : give distance info

only.

- Stereo amplifier – give position info and separation sound.

- Type of speaker :-a. Moving coil - Common use. Able

to stand overload / Coil place at the magnet chink.

b. Piezoelectric - Good for high freq / i.e. watch

c. 2 way speaker – suitable for sound reinforcement / Freq range suitable to be heard.


LINE ARRARY SPEAKER


3. Amplifier- Amplify audio signal.- Tone control available. - Power per channel not more

than 100W- Input signal from CD have

better distortion compare to the cassette i/p.

MIXING AMPLIFIER/PUBLIC ADDRESS


Method of Power line distribution to

the speakers

Speaker selection based on : – - Sound strength - Speaker quantity - Low power amplifier –

slow sound - High power amplifier –

damage the speaker


For o/p amplifier low impedance;

- total impedance value for all speakers should higher @ same value with the o/p amplifier

Total o/p amplifier ≤ Combination of speaker

impedance impedance For o/p amplifier high impedance ; - total power supplied to the speaker

should be lower than the o/p amplifier capability.

Total power supplied to speaker ≤ o/p amplifier


Low Impedance Amplifier Amplifier produce full power o/p. The amplifer attached with speaker

connection point that is labelled with ‘Com., 4Ω, 8Ω dan 16Ω’.

Variety connection of the speaker method can be implement as long as the total impedance connected to the amplifier is suitable with the value of the amplifier terminal connection point.

16Ω

8Ω4Ω

Com.

4Ω8Ω 4Ω


High impedance amplifier Speaker installation method for this amplifier is

called ‘Constant Voltage Distribution System’ (Sistem Agihan Voltan Tetap)

The amplifer attached with speaker point that is labelled with ‘Com., 4Ω, 8Ω dan 16Ω’.

All the speaker connection is in parallel via transformer for impedance matching.

Voltage distribution value normally from 70V – 100V.

High impedance terminal

Low impedance terminal

CC

CC

CC

Primary Secondary

70V @ 100V line


Type of the speakers & the range that will divide the speaker categories.

High impedance

Mark at the amplifier for high impedance connection

mark of 70V, 100V & 110V.

Speaker condition For range more than 10 m. Every speaker is attached with MT. Horn type speaker.


Matching Transformer (MT)

Attached with Horn Speaker type.

MT will match power which was produced

by amplifier with rating to Horn speaker.

In other words, amplifier will induce MT and MT's output power to produce Horn speaker sound.

This method can extend life time’s of the

speaker.


Type of speakers & the range that will divide the speaker categories.

Low impedance

Mark at the amplifier for low impedance connection

Mark of 4Ω, 8Ω & 16Ω.

Speaker condition that is categorized as high impedance connection

For range less than 10 m. Speaker value – not same Papercone & ceiling type speaker.


Speaker Selection Avoid non clearity problem and

low power sound. Class of Speaker 1. Open place - freq waveform

between 800 Hz ~ 6000 Hz 2. Music background – for gentle

music freq between 100 Hz ~ 800Hz

3. Music – refer to the hall condition/ design for music 40Hz ~15000Hz


Speaker Arrangement 1. Main System - Speaker place at the center of the hall to control sound convergence to one direction. Low maintenance cost. 2. Spreading System - Scattered arrangement for speakers. - Speaker combination can strengthen sound at the small space. - However the sound quality is reduce. 3. Combination System - Combination of 2 system.


Arrangement & Speaker power distribution at

the internal building area. When setting the location of speaker in

a room, factor of level of noise, height of ceiling, wide area of the room, use of the speaker & etc.

Below shows the criteria taken on speaker installation :-Speaker Keluasan kawasan bagi memperolehi 76dB

keluaran maksima

WT – 707N (7W)

WT – 715N (15W)

WT – 202AN (10W)

WT – 200AN (15W)

Kira-kira 32m persegi





Introduction to the Sound Reinforcement system and the different with the PA system.

Sound Reinforcement system is used to produce an high energy sound signal in a wider area.

Suitable for musical & vocal while PA system is suitable for speech and lecture session.

Additional equipment can increase the capability of PA system to be a sound reinforcement system.


The different between PA system and Sound Reinforcement system.

PA System Sound Reinforcement

Limited space for equipment.

Wide area for equipment

Level of sound spreading are not wider.

Wider of level of sound spreading

Lower cost More expensive cost

Low level of power & equipment consumption.

High power and use many equipment.

Suitable for general broadcasting

Suitable for music

Have 1 output channel Have 2 output channel

1 channel o/p connected to a numer of speaker

2 o/p channel which each o/p have 1 speaker


Speaker

PointB Point A Point C

Determination of Speaker Location


DVD Player Equalizer Limiter

Crossover

Speakers

Sub-woofer

Amplifier

Amplifier

Wireless Mic

Mixer

Microphone

SOUND SYSTEM FOR 300 PEOPLE

Canon jack to mono jack cable

2 to 2 rca plug

3 to 3 rca cable

Speakon plug to speakon plug cable

Speakon plug to speakon plug cable


Additional equipment for

Sound Reinforcement

System


AUDIO COMPRESSOR

Audio compressor – to compress @ limitting audio signal range.

Automatically fixed the signal level before send it to tape for recording

The compress process – to allow high/ low sound to be adjusted.


Basic control system in the compressor for user :-

* I/P – Set i/p level

* Treshold – set level as a reference

before the compressor operate.

* Ratio – Set ratio to the rise of dB

at the signal below treshold level.

i.e. : Set 4:1 – bila treshold level dicapai, hanya 1dB kenaikan pd

o/p utk setiap 4dB kenaikan pd i/p

signal.


* Attack – Time taken to act when the signal cross the treshold level. * Decay – Time taken back to normal condition when the

signal become below the treshold

level.

* O/P - Set o/p level.


AUDIO COMPRESSORCircuit Operation

IC1 act as amplifier where the gain determine by the R1– resistor between Drain & Source FET 2N3819. R1, R2 & R3 determine FET V-I characteristic.

O/p circuit connected with the feed back circuit.

Attack and Decay controlled by R4 (1ms) and R5 (517ms)


AUDIO COMPRESSORCircuit Operation

2 way switch – select compressor working condition –fix gain @ adjustable.

VR1 – adjustable gain R4, R5 & feedback connection

– fixed gain In this circuit, a 29dB change

in the input signal level produces a 9dB change in the output.


AUDIO MIXER

Audio mixer is used to mix many type of i/p sound signal.

Normally there is 8 ~ 10 input. Low freq., mid range freq. &

high freq. The gain for i/p signal can be

controlled to follow needs of user @ to get any special effect.


AUDIO GRAPHIC EQUALIZER Problem encounter - copying video

tapes is the deterioration in the sound quality.

To correct the sound signal to produce the o/p sound approx. near to the original sound. ( by correcting the freq response ) .

5 band equalizer design to connect 2 AV o/p component to produce freq response that can be controlled.


The five controls each have a range of +/- 10dB at centre frequencies of 100Hz, 300Hz, 1KHz, 3KHz & 10KHz.

The 3dB points on each band are

at 1/2 and twice the centre frequencies.

Thus, the 3dB points on the 100Hz control are at 50Hz and 200Hz. With all controls at maximum the unit has a total gain of 15dB. The unit will accept an input of up to about 1V RMS (3V pk-pk) before distortion occurs with all controls at maximum.


AUDIO GRAPHIC EQUALIZERCircuit operation

I/p is buffered by the IC1, (non-inverting with gain) which the gain can be controlled by altering R1 & R4.

For easier explaination, assume 5 frequency selective sections disappeared, as well as five of the control pots. The wiper of the remaining pot is connected to ground via a 1K0 resistor. So, the gain is 10.

So, if the 1k replaced back to the 5 band freq,

it shows that the gain can be adjusted.


This cct is using capacitor and inductor in series connection as an adjuster. Gyrator model cct is used to replace the inductor due to difficulty

Refer to the cct, C2 - capacitor. Whereas, C3, R7 & R8 act as inductor. Value of C3 will determine the freq for each band.

In the last IC3 will function as Unity Gain buffer.

SW1 act as selector switch to select unit to be in equalizer mode or not.


SOUND PROCESSOR

Function to change & adjust the sound structure to produce the best sound o/p.

The sound effect that can be produce by this processor is like echo (gema), surround (modulasi keliling) etc.

Normally used in the computer and television application.

* A rapid repetition of the same note, a rapid variation in the amplitude of a single note, or an alternation between

two or more notesThis is more usually called vibrato.


Sound Delay Cct

To delay the signal, which makes the sound are far away.

Normally in surround decoder cct where the o/p will provide a passable rear channel signal.

As example, IC M65830 is use.

This IC need 5V supply. Whereas pin 11 & 12 need good separation between ground for analog and digital signal

DELAY +/-

I/P To O/P


Cap 68nF at pin 16 & 20 – to control modulation ( conversion of digital & analog) & demodulation. However the tolerance should not exceeds 5% to get good result.

I/P driver cct – to decrease the i/p value signal to avoid overload. The max value for this IC i/p is 1 Vrms.

This is because signal for CD player normally at 2.5 Vrms. So, by using the driver cct, the signal can be decrease.

Ch 4.3 - Sound System

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