1 Paging and distributed speaker systems BASIC TELECOMMUNICATIONS

2 Paging systems are typically built into telephones connected to a PBX using only the speaker on the telephone set In order to have an effective paging system the use of an amplifier and additional speakers throughout the building is necessary Paging systems are typically built into telephones connected to a PBX using only the speaker on the telephone set In order to have an effective paging system the use of an amplifier and additional speakers throughout the building is necessary BASIC TELECOMMUNICATIONS

3 Distributed speaker systems refer to a network of horns and speakers which are connected to an audio amplifier using step-up and step-down transformers built into speakers to simplify impedance calculations and to minimize power loss over the long cable runs BASIC TELECOMMUNICATIONS

4 Most systems are either 25V, 70.7V and 100V Wattage can range from 1/4W to 200W The most commonly used system is a 70.7V system that is connected to a PBX Most systems are either 25V, 70.7V and 100V Wattage can range from 1/4W to 200W The most commonly used system is a 70.7V system that is connected to a PBX BASIC TELECOMMUNICATIONS An amplifier that is designed to work in conjunction with a PBX

5 Lets take a look at some of the components of a distributed speaker system A desk top mic Tone generator AM/FM receiver Lets take a look at some of the components of a distributed speaker system A desk top mic Tone generator AM/FM receiver BASIC TELECOMMUNICATIONS

6 PBX interface module 2 different types of volume controls/attenuators PBX interface module 2 different types of volume controls/attenuators BASIC TELECOMMUNICATIONS

7 Standard indoor ceiling speaker and T-bar to hold the speakers into a 2’ x 2’ drop ceiling grid 2’ x 2’ grid speaker Standard indoor ceiling speaker and T-bar to hold the speakers into a 2’ x 2’ drop ceiling grid 2’ x 2’ grid speaker BASIC TELECOMMUNICATIONS

8 A standard horn and Explosion proof outdoor horn BASIC TELECOMMUNICATIONS

9 In it’s most basic form a distributed speaker system consist of an input (microphone & music), an amplifier, and speakers (indoor and outdoor) IMPEDANCE MATCHING IS A KEY CONSIDERATION HERE Remember impedance is a form of resistance and better matching of components allows for better power usage and sound clarity In it’s most basic form a distributed speaker system consist of an input (microphone & music), an amplifier, and speakers (indoor and outdoor) IMPEDANCE MATCHING IS A KEY CONSIDERATION HERE Remember impedance is a form of resistance and better matching of components allows for better power usage and sound clarity BASIC TELECOMMUNICATIONS

10 The power amplifier output must be matched to the effective impedance of the speaker system Because it is often necessary to use more than one speaker system (per channel) to disperse sound to the entire area, two or more speaker systems must be wired together The power amplifier output must be matched to the effective impedance of the speaker system Because it is often necessary to use more than one speaker system (per channel) to disperse sound to the entire area, two or more speaker systems must be wired together BASIC TELECOMMUNICATIONS

11 There is only three possible ways to connect speakers to a power amplifier, common ground and only one power amplifier terminal can be connected at one time What are the three wiring configurations that speakers can be connected? For best results, all speaker systems installed should have the same impedance There is only three possible ways to connect speakers to a power amplifier, common ground and only one power amplifier terminal can be connected at one time What are the three wiring configurations that speakers can be connected? For best results, all speaker systems installed should have the same impedance BASIC TELECOMMUNICATIONS

12 Notice here that one lead connects to common and the other to the desired output impedance LETS LOOK AT THE 3 CIRCUIT TYPES Notice here that one lead connects to common and the other to the desired output impedance LETS LOOK AT THE 3 CIRCUIT TYPES BASIC TELECOMMUNICATIONS 8 Speaker

13 Here are the three different circuit types BASIC TELECOMMUNICATIONS

14 Since each speaker system has its own impedance, wiring them together changes the effective impedance presented to the power amplifier Based on the type of speakers you have to work with you will need to determine how to wire them to match the impedance output of the paging amp Series, parallel or series/parallel Since each speaker system has its own impedance, wiring them together changes the effective impedance presented to the power amplifier Based on the type of speakers you have to work with you will need to determine how to wire them to match the impedance output of the paging amp Series, parallel or series/parallel BASIC TELECOMMUNICATIONS

15 For speaker systems connected in series, simply add the impedances of all the speakers. Example, if you connect two, 8-Ohm speakers in series, the effective impedance is 16-Ohms. You then use the 16-Ohm output on the power amplifier for proper impedance matching. Four, 4-Ohm speaker systems could be connected in series for the same 16-Ohm effective impedance For speaker systems connected in series, simply add the impedances of all the speakers. Example, if you connect two, 8-Ohm speakers in series, the effective impedance is 16-Ohms. You then use the 16-Ohm output on the power amplifier for proper impedance matching. Four, 4-Ohm speaker systems could be connected in series for the same 16-Ohm effective impedance BASIC TELECOMMUNICATIONS

16 There is a practical limit to the number of TIC speaker systems that can be effectively connected in series Example, connecting four TIC 8-Ohm speaker systems in series presents an effective impedance of 32-Ohms to the amplifier This is a decidedly bad idea There is a practical limit to the number of TIC speaker systems that can be effectively connected in series Example, connecting four TIC 8-Ohm speaker systems in series presents an effective impedance of 32-Ohms to the amplifier This is a decidedly bad idea BASIC TELECOMMUNICATIONS

17 An impedance mismatch at the power amplifier causes distorted sound because the amplifier is asked to operate at maximum voltage swing If you connect speaker systems in parallel, and all have the same impedance, the effective impedance equals the impedance of one speaker system divided by the number of speaker systems An impedance mismatch at the power amplifier causes distorted sound because the amplifier is asked to operate at maximum voltage swing If you connect speaker systems in parallel, and all have the same impedance, the effective impedance equals the impedance of one speaker system divided by the number of speaker systems BASIC TELECOMMUNICATIONS

18 Example, if two speaker systems rated at 8-Ohms each are connected in parallel, the effective impedance is 4- Ohms 8 divided by two=4 The 4-Ohm power amplifier output must be used Example, if two speaker systems rated at 8-Ohms each are connected in parallel, the effective impedance is 4- Ohms 8 divided by two=4 The 4-Ohm power amplifier output must be used BASIC TELECOMMUNICATIONS

19 Similarly, if four speaker systems rated at 16-Ohms each are connected in parallel, the effective impedance is 4-Ohms The 4-Ohm power amplifier output must be used Do not forget that the wiring pattern for speakers related to the output channels of the amplifier will determine how the system will be wired! Similarly, if four speaker systems rated at 16-Ohms each are connected in parallel, the effective impedance is 4-Ohms The 4-Ohm power amplifier output must be used Do not forget that the wiring pattern for speakers related to the output channels of the amplifier will determine how the system will be wired! BASIC TELECOMMUNICATIONS

20 Series connected BASIC TELECOMMUNICATIONS 4 ohms each

21 Parallel connected BASIC TELECOMMUNICATIONS 16 ohms each

22 Series/Parallel connected BASIC TELECOMMUNICATIONS 2, 16 ohm speakers 2, 4 ohm speakers

23 In the diagram below can you identify the 3 different circuits and determine the value of each speaker? BASIC TELECOMMUNICATIONS

24 For speaker systems connected in parallel that don’t have the same impedance, use the following equation to find effective impedance (Zt); Z = Impedance For speaker systems connected in parallel that don’t have the same impedance, use the following equation to find effective impedance (Zt); Z = Impedance BASIC TELECOMMUNICATIONS

25 From Valcom a sample speaker placement chart For optimum audible intelligebality From Valcom a sample speaker placement chart For optimum audible intelligebality BASIC TELECOMMUNICATIONS