Section 16826
2000-06-01Public Address System
This Master Specification Section contains:
.1This Cover Sheet
.2Specification Section Text:
1.General
1.1Related Requirements
1.2System
2.Products
2.1Components
3.Execution
3.1Installation
BMS Basic Master SpecificationAlberta Infrastructure
Master Specification System / Page 0
Section 16826
Plan No:Public Address System
Project ID:Page 1
1.General
1.1RELATED REQUIREMENTS
.1Electrical General Requirements: Section16010.
1.2SYSTEM
.1This section includes a public address system with multi point microphone input facilities and provisions for background music.
2.Products
2.1COMPONENTS
.1Microphones:Low impedance, handheld dynamic type with frequency response 100 to 7000 Hz. Size:65mm wide, 100mm high, 40mm deep. Colour:communications grey. Microphone shall be complete with 1.5m coiled cord complete with 90° cannon plug. Complete with On/Off switch.
.2Mixer 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:
.1Rated output:+28 dbm transformer isolated, 150/600 Ohm, balanced. Distortionless than 0.5% at +28 dbm, 20 to 20 000 Hz.
.2Frequency response:20 to 20 000 Hz + Idbm.
.3Sensitivity:Microphone:250 microvolts.
Magentic:5 microvolts.
High Level:4 millivolts.
Line:400 millivolts.
Input attenuator set for maximum gain.
.4Noise 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 [600to25000 Ohm.
.5Load Impedance: 150 or 600 Ohm.
.6Monitor 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.
.7Controls 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.
.3Dynamic 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 response20 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 impedancematching 600 Ohm. Bridging 10 000 Ohm. Output impedance600 Ohm. Noise [threshold of compression]70 db. Noise level [Dynamic noise amplifier "On"]80 db. Compression ratios10 to 1 and 5 to 1. Compression attack timeless than 30 microseconds. Compression release time1.5 seconds. Controlsinput level [gain], output level [gain], meter switch, power switch, compression disable, compression ratio, noise amplifier disable. Compression ratios10 to 1 and 5 to 1. Compression attack timeless than 30 microseconds. Compression release time1.5 seconds. Controlsinput level [gain], output level [gain], meter switch, power switch, compression disable, compression ratio, noise amplifier disable.
.4Audio 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 output50W [rms. Distortionless than 1.5%. 30 to 20 000 Hz. Frequency response20 to 20 000 Hz +2 db at 3 db below rated output. Noise level80 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.
.5Loudspeakers:permanent magnetic cone type, diameter of 200mm, 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 25mm in diameter. Frequency response 30 to 13 000 Hz, ±5 db.
.6Loudspeaker Matching Transformers:multitop 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.
.7Loudspeaker Baffles [Flush Mounted]: [].
.8Wiring and Cable 19/2 PVC insulated twisted pair for multi speaker hookup.
.9Conduit:Refer to Section 16131.
.10Amplifer 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 corrosionresistant primer. Amplifer rack to incorporate ac strip kit assembly, 100mm 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 [].
.11Heat Deflectors:[] finished to match the main equipment.
3.Execution
3.1INSTALLATION
.1Install sound equipment as indicated on the drawings.
.2Wiring shall be installed in conduit where installed in wall or above nonremoveable ceilings. Open wiring in all removeable ceiling areas.
.3Where 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.
.4On complete of installation check system for operation, adjust transformer tap settings and leave system fully operational.
END OF SECTION