Public Address System In Electrical Construction Contract



The contractor shall supply, installation, test and commission a public address system consisting of power amplifier, mixer power amplifier, microphone module, paging console, cabinet rack, conduits and wiring and all the necessary equipment required by the system shown and described on drawings, bill of quantities and hereinafter.



Distribution of Public Address System

100 V, line distribution shall be accepted for sound system distribution in the project.

Public Address System Description

Power Amplifier

The power amplifiers, mixer power amplifiers shall be fully transistorized and capable of delivering 120, 60, 30 watts (RMS) audio power at less than 1% distortion over the frequency range of 40 Hz to 16 KHz.

Technical specification for Public Address System


  1. Frequency response: 40 Hz to 16 KHz ± 2db at rated output.
  2. Distortion: Less than 1% (at rated output F = 1 KHz).
  3. Input: 2 program and 2 priority inputs with program input muting during priority operation.
  4. Power source: Operate on both AC mains and 24 V Dc.
  5. The power amplifier shall be rack mounted type.

Signal Generator

The generator shall be completely solid state and produce a chime signal consisting of two tones with 200Hz difference.  It should be capable of generating a test signal for testing the amplifier and loudspeakers.

Desk Microphone Assembly

3.3.1 The desk microphone assembly shall be designed to suit the number of zones required (24 Zones).

Technical specification of Public Address System

  1. Remote controls: 12 individual controls and 1 all call control.
  2. Distortion: Less than 1%.
  3. Signal to noise (S/N): 56 dB.
  4. Microphone: Unidirectional dynamic microphone with sensitivity -76 dB ± 3 dB.
  5. Program function: 2 user programmable function (first in first severed) priority dia cascade priority.


  1. Busy: red LED.
  2. Speech: green LED.
  3. Chime: red LED.

Column Loudspeaker

The column loudspeaker shall be 20 W or 10 W capacity as specified indoor type with matching transformer 100 V complete with bracket. The columns speaker shall be metal case type.

Ceiling Speaker

The ceiling speaker shall be 6 W capacity recessed round type, 19 cm baffle gray HIPS case cone speaker with silver aluminium punching.

Technical specification

  1. Input: rated 6 W, max. 9 W.
  2. Frequency response: 100 - 12000 Hz.
  3. Sound pressure level: input 1 W, 1 m, 91 dB / input 6 W, 1 m, 98.8 dB.
  4. Usable line voltage: 100 V line.

The loudspeaker shall be equipped with matching transformer suitable for use on 100 V output line.

Cabinet Rack

The cabinet rack shall comply with EIA (universal spacing) and IEC mounting pitch, and will have Pale ivory (off-white) leather tone color.