Bogen UTI312 User Manual download pdf (Page 5)

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SYSTEM DESIGN GUIDE

Self-Amplified Paging Systems consist of:

• Self-Amplified Speakers each contain an individual, built-in,

miniature amplifier that drives the speaker directly. Each speaker

requires 4 wires.Two wires supply the raw 24V DC voltage to

power the speaker’s internal amplifier and another 2 wires

supply the low level audio paging signal to the amplifier’s input.

All amplified speakers contain volume controls to adjust

output level.

• A Power Supply or multiple power supplies which supply the

raw 24V DC voltage that will power the amplifier built in to each

self-amplified speaker. Several power supplies can be located in

convenient areas in the facility.

• An Interface Device that connects the paging system to back-

ground music sources and the telephone system and supplies a

telephone level audio paging signal to all the speakers in the system.

(Depending on the telephone system and number of speakers in

the system, an interface device may not be needed.)

What Is A Self-Amplified System?

A self-amplified system can be expanded by adding extra speakers and

power supplies as required.They are extremely scalable due to the

fact that each speaker is an amplifier unto itself. It is also easy to

connect additional power supplies where needed to power the

speakers. In some instances there may not be sufficient audio signal

level available for the speaker’s input. In these instances a small buffer

can be installed inline to boost the signal level.

Self-amplified speakers can also be used to expand 70V paging systems

in cases where the added speakers would overload an existing central

70V amplifier.The same buffer that is used to boost signal level can be

used to reduce the large 70V speaker signal to a level that is compati-

ble with the input of self-amplified speakers. A suitable power supply

can be located near the expansion speakers to power their internal

amplifiers.This approach can be used instead of replacing the central

70V amplifier with a larger one to handle the extra speakers.

Convenient System Expansion

Self-Amplified paging systems are made up of equipment that

consume or provide operating current.To operate properly,

the system needs to provide at least as much 24V current as

it consumes.

Each product has a Current Units number.This number is

either positive, negative, or zero to indicate how much current

it provides or consumes from the system.

Note: One Current Unit = 50 mA, 24V DC

Understanding Current Units

Low Signal Levels Prevent Crosstalk

In certain installations it may be desirable to use conductors in an

existing telecommunication cable to deliver paging to different floors

or areas in a facility. 70V amplifier signals would not be appropriate to

run in the same cable with analog telephone signals since their high

level could cause crosstalk in the other telephone circuits in the

cable. Because the audio signal levels supplied to the inputs of the

amplified speakers are similar in level to analog telephone levels, there

will be no crosstalk of the paging system in the telephone lines.

The raw 24V DC power needed by the self-amplified speaker can

also be carried in the telecom cable since it contains no interfering

signals, but care must be exercised to make sure the length of cable

will not cause too much voltage to be lost in the cable.

Why Use Self-Amplified Technology?

Self-amplified speakers can be very cost effective in small systems

since they provide scalability in small increments.The centralized

amplifiers in 70V systems are typically available in set output power

levels steps that start at 6 or 10 watts and increment by 10 watts or

more from model to next higher powered model. In small applica-

tions that require only a few watts of paging, the extra power capabil-

ity of the 70V amplifiers may not be an advantage due to the higher

cost associated with the amplifier’s extra power, especially if it will

not be used in the future.

Self-amplified systems can be designed with much smaller output level

power steps so that only the necessary audio power is installed in

the facility. This can result in a lower cost of equipment especially

where the desired power level is considerably less than the smallest

applicable 70V amplifier output level.

Cost Effective for Small Installations

108

Provides

System Current

108

Consumes

System Current

108

No Draw

on the System

AUDIO

DC POWER

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Bogen UTI312 User Manual Page 5

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