Download 16826 - Public Address System

Section Cover Page
Section 16826
Public Address System
2000-06-01
This Master Specification Section contains:
.1
This Cover Sheet
.2
Specification Section Text:
1.
1.1
1.2
General
Related Requirements
System
2.
2.1
Products
Components
3.
3.1
Execution
Installation
BMS Basic Master Specification
Alberta Infrastructure
Master Specification System
Page 0
Section 16826
Public Address System
Page 1
Plan No:
Project ID:
1.
General
1.1
RELATED REQUIREMENTS
.1
1.2
Electrical General Requirements:
Section 16010.
SYSTEM
.1
This section includes a public address system with multi point microphone input facilities
and provisions for background music.
2.
Products
2.1
COMPONENTS
.1
Microphones: Low impedance, handheld dynamic type with frequency response 100 to
7000 Hz. Size: 65 mm wide, 100 mm high, 40 mm deep. Colour: communications grey.
Microphone shall be complete with 1.5 m coiled cord complete with 90° cannon plug.
Complete with On/Off switch.
.2
Mixer Preamplifier: complete solid state providing five [5] input channels for
microphones, high level or magnetic input as required. Separate speech filter
incorporated in each channel. Unit complete with master gain control, power On/Off
switch and VU meter. Technical specification as follows:
.1
Rated output: +28 dbm transformer isolated, 150/600 Ohm, balanced.
Distortion - less than 0.5% at +28 dbm, 20 to 20 000 Hz.
.2
Frequency response: 20 to 20 000 Hz + Idbm.
.3
Sensitivity:
.4
Noise level: with master gain control up, 90 db below rated output. Inputs: 5
channels, each channel may be used for balanced low impedance microphone
[150/250] Ohm nominal], mag. phono, line or high level [600 to 25 000 Ohm.
.5
Load Impedance: 150 or 600 Ohm.
.6
Monitor Output: +10 dbm to 600 Ohm load. Rear panel monitor monitor
amplifier outputs 0.8 V to 10 000 Ohm or +10 dbm to 600 Ohm single ended.
Microphone:
250 microvolts.
Magentic:
5 microvolts.
High Level:
4 millivolts.
Line:
400 millivolts.
Input attenuator set for maximum gain.
Section 16826
Public Address System
Page 2
Plan No:
Project ID:
.7
Controls and Indicators: 5 input level, 1 master, 1 base and 1 treble each 3 db per
step to +15 db, 1 monitor, 1 output switch, 1 power switch, 1 VU range, 5 speech
filter switches (-10 db at 100 Hz), 5 input attenuator switches, illuminated VU
meter.
.3
Dynamic Range Limiter: on the line side of the transformer matched mixer there shall be
a combined compression amplifier with an instantaneous operating noise gate which
reduces the "No Signal" noise by 15 db. Attack time of the compressor section shall be
less than 30 microseconds with a release time of 1.5 seconds. Noise gate shall have a one
microsecond attach time with a 200 millisecond release time. Unit shall be designed to
operate from a 600 volt line at levels from -30 to +28 dbm. Unit to have a direct reading
compression meter and up to 40 db of signal compression with 5:1 and 10:1 compression
ratio. Unit technical specifications shall be as follows: Rated output - +14 dbm.
Maximum output - +28 dbm. Distortion [THD] - straight amplifier, 0.5%, with up to 40
db compression, 0.5%. Frequency response - 20 to 20 000 Hz + 1 db. Gain - [600 Ohm]
at threshold of compression 51.5 + db. [Bridging] at threshold of compression 14 +2 db.
Input impedance - matching 600 Ohm. Bridging 10 000 Ohm. Output impedance - 600
Ohm. Noise [threshold of compression] - 70 db. Noise level [Dynamic noise amplifier
"On"] - 80 db. Compression ratios - 10 to 1 and 5 to 1. Compression attack time - less
than 30 microseconds. Compression release time - 1.5 seconds. Controls - input level
[gain], output level [gain], meter switch, power switch, compression disable, compression
ratio, noise amplifier disable. Compression ratios - 10 to 1 and 5 to 1. Compression
attack time - less than 30 microseconds. Compression release time - 1.5 seconds.
Controls - input level [gain], output level [gain], meter switch, power switch,
compression disable, compression ratio, noise amplifier disable.
.4
Audio Power Amplifier: totally solid state with silicone transistors used exclusively.
Unit to incorporate temperature stabilized circuitry, electronic power limiting, output
stage protection and shall meet the following technical specifications: Rated
output - 50 W [rms. Distortion - less than 1.5%. 30 to 20 000 Hz. Frequency
response - 20 to 20 000 Hz +2 db at 3 db below rated output. Noise level - 80 db below
rated output. Input sensitivity - 0.4 V for rated output. Input impedance - 100 000 Ohm,
single ended. Load impedance - 100 Ohm [70 V] balance or single ended. 12.5 Ohm [25
V] balance or single ended. 25 Ohm single ended.
.5
Loudspeakers: permanent magnetic cone type, diameter of 200 mm, nominal continuous
wattage rating II watts, axial sensitivity with one watt input not less than 84.5 db at 3 m
on axis. Permanent magnet - ceramic, mass of not less than 170 g. Voice coil - not less
than 25 mm in diameter. Frequency response - 30 to 13 000 Hz, ±5 db.
.6
Loudspeaker Matching Transformers: multi-top type 0.25 to 4 W 25 V line [70 V line.
Frequency response - 100 to 10 000 Hz +1 db. Maximum insertion loss - 1 db. Output
impedance - 8 Ohm. Loudspeaker enclosure - flush mounted.
.7
Loudspeaker Baffles [Flush Mounted]: [
].
Section 16826
Public Address System
Page 3
Plan No:
Project ID:
.8
Wiring and Cable - 19/2 PVC insulated twisted pair for multi speaker hook-up.
.9
Conduit: Refer to Section 16131.
.10
Amplifer Rack: constructed of rigid metal frame with totally enclosing Code gauge metal
panels louvred where required for ventilation. Rack finished in colour selected by the
Minister over corrosion-resistant primer. Amplifer rack to incorporate ac strip kit
assembly, 100 mm heavy duty industrial type casters with stop lock assembly, fan kit
assembly bottom mounted delivering not less than [140 L/s] [300 cfm] through rack
complete with thermostat and manual motor protection switch. Amplifier rack [
].
.11
Heat Deflectors: [
3.
Execution
3.1
INSTALLATION
] finished to match the main equipment.
.1
Install sound equipment as indicated on the drawings.
.2
Wiring shall be installed in conduit where installed in wall or above non-removeable
ceilings. Open wiring in all removeable ceiling areas.
.3
Where loudspeaker enclosures are mounted in removeable acoustic tile type ceiling the
backbox to be supported totally independent of ceiling tile by means of two metal angle
channels fastened to the speaker enclosure spanning in between supporting tee bar ceiling
channels. No wood type support or wire hanging type support to be used.
.4
On complete of installation check system for operation, adjust transformer tap settings
and leave system fully operational.
END OF SECTION