[Audio Network Information] As a system, public broadcasting must comprehensively consider the influence of various factors on the system. Therefore, on the basis of selecting electro-acoustic equipment with excellent performance, through careful system design, careful system debugging and good sound-building conditions, it is possible to achieve sound and natural sound effects.
The public address system is a branch of the sound reinforcement system, and the sound reinforcement system is also called the edge science of the three major disciplines of electroacoustic, sound and music. Therefore, the final effect of the public broadcasting system involves the reasonable and correct design and commissioning of the electroacoustic system, the best combination of the sound transmission environment (the sound construction condition) and the precise on-site tuning. The three complement each other.
As a system, public broadcasting must comprehensively consider the influence of various factors on the system. Therefore, on the basis of selecting electro-acoustic equipment with excellent performance, through careful system design, careful system debugging and good sound-building conditions, it is possible to achieve sound and natural sound effects. The following is a small series of tips for the design and installation of public address systems and emergency broadcast systems. Let's share with you:
Public Broadcasting System Design Tips:
(1) Transmission mode: The output power feeding mode of the system adopts cable broadcast transmission mode.
(2) Line attenuation requirements: In the public address system, the line attenuation from the output of the power amplifier equipment to the farthest user speaker on the line should meet the following requirements:
· Service broadcast should not exceed 2 decibels (at 1 kHz)
· Service broadcast should not exceed 1 decibel (at 1 kHz)
(3) Feed line with constant voltage output, the output voltage is 70V or 100V.
(4) Calculation method of power amplifier capacity:
Calculation methods for operational broadcast systems and operational broadcast systems:
P=K1×K2×ΣPo
Where: P--power amplifier output total electric power (W);
Po--Ki×Pi, the maximum electric power (W) when each sub-channel is broadcast simultaneously;
Pi--the rated capacity of the user equipment of the i-th branch;
Ki--the ith branch requires a coefficient at the same time;
In the case of service broadcasting, each set of Ki in the room program is 0.2-0.4;
Background music program Ki takes 0.7-0.8
K1--line attenuation compensation coefficient: 1.26 when the line attenuation is 1dB;
When the line attenuation is 2dB, take 1.58;
K2--aging coefficient, generally taking 1.2-1.4;
· Calculation method of fire accident broadcasting system:
There are two ways to calculate the system:
a. The power amplifier capacity is determined by 1.3 times the total number of speakers in the system.
b. The power amplifier capacity is determined by 1.5 times the total number of the largest 3-layer speakers in the system.
(5) The power amplifier of the standby public address system of the power amplifier should be provided with a backup power amplifier, which can be automatically or manually used when the working power amplifier fails. Power amplifiers for important broadcasts (such as power amplifiers for fire accident broadcasts) should have their standby power amplifiers ready for immediate use in the event of a malfunction of the operating amplifier. The number of spare power amplifiers should be determined based on the capacity of the important broadcast load.
(6) Speaker settings
• Set up a 3W speaker box in the office, living room, locker room, etc.
· Floor corridors generally use ceiling-mounted speakers, and the spacing of the speakers is considered to be about 2.5 times the height of the floor (the height of the ceiling). Choose 3-5W ceiling speaker.
· 3-6W speaker box should be installed in the entrance hall, general meeting room, restaurant, shopping mall, entertainment place, etc.
· 1W-2W speaker is used in the bedside control cabinet.
· In the case of building decoration and room height allowance, sound column or combination speaker should be used for large space.
• When setting up the speaker in a noisy, humid place, use a horn speaker. The sound pressure level of the horn loudspeaker selected in a place with high noise should be 10-15 dB greater than the ambient noise.
(7) Power supply requirements for broadcasting systems
· The small-capacity broadcasting station can be directly powered by the socket; when the capacity is above 500W, the broadcast control room is set, and the power supply can be supplied by the nearest power controller dedicated line.
· The AC voltage offset value should not be greater than +10%. When the voltage offset cannot meet the requirements of the equipment, an automatic voltage regulator should be installed near the equipment.
· The AC power supply capacity for broadcasting is generally 1.5-2 times the AC power consumption capacity of the final broadcast equipment.
· Fire accident broadcast equipment uses fire power.
(8) Choice of transmission cable · Room service broadcast line should use copper core multi-core cable or copper core plastic stranded wire.
· Other broadcast lines should use copper core plastic stranded wire. • Shielded lines should be used for various program signal lines.
· Fire-fighting accident broadcast lines should use flame-retardant copper core cable or fire-resistant copper core wire and cable.
(9) Laying method of the line • The line shall be laid with steel pipe or wire trough, and shall not be laid in the same line as the lighting and power lines.
· Fire alarm protection measures should be taken for fire accident broadcast lines.
Emergency Broadcast System Design Tips:
(1) The setting of the fire accident broadcast speaker should meet the following requirements:
• Emergency broadcast speakers should be placed in public places such as walkways, halls, restaurants, etc., and the number should be such that the walking distance from any part of the floor to the nearest speaker is no more than 25 meters. Speakers should be placed at the intersection of the walkway and at the corner. The last speaker at the end of the walkway is no more than 12 meters from the wall. The rated power of each speaker should not be less than 3W.
· The speaker power in the room should not be less than 1W.
· Speakers with background noise in air-conditioned machine rooms, ventilation rooms, laundry rooms, entertainment venues and parking garages. The sound pressure level of the farthest playback in the playback range should be 15dB higher than the background noise, and the speaker should be determined accordingly. power.
(2) The fire alarm broadcast feeder voltage should not be greater than 100V. The feeder isolation voltage is set on each floor to ensure that when any of the branches is faulty, the normal broadcast of other branches should not be affected.
(3) The fire accident broadcast output shunt shall be controlled according to the evacuation order. The floor control procedure for playing the evacuation command is as follows:
• In the event of a fire on the N and N floors, the upper and lower floors of the fire layer should be connected first.
· In case of fire on the first floor, the floor, the second floor and the underground floor should be connected first.
· In case of fire in the basement, the underground floor and the first floor should be connected first.
(4) When a fire accident broadcast is used in conjunction with a service broadcast or a commercial broadcast, the following requirements shall be met:
· In the fire control room, the speaker and corresponding power amplifier of the fire evacuation layer should be forcibly transferred to the fire accident broadcast state.
· The fire control room should be able to monitor the working status of the fire amplifier.
· Speakers should be installed in the bedside table of the room and should have a fire broadcast function.
• If the fire accident broadcast is combined with a service broadcast or a commercial broadcast with a volume switch, the system should use a three-wire system to force the fire to be broadcast.
The public address system is a branch of the sound reinforcement system, and the sound reinforcement system is also called the edge science of the three major disciplines of electroacoustic, sound and music. Therefore, the final effect of the public broadcasting system involves the reasonable and correct design and commissioning of the electroacoustic system, the best combination of the sound transmission environment (the sound construction condition) and the precise on-site tuning. The three complement each other.
As a system, public broadcasting must comprehensively consider the influence of various factors on the system. Therefore, on the basis of selecting electro-acoustic equipment with excellent performance, through careful system design, careful system debugging and good sound-building conditions, it is possible to achieve sound and natural sound effects. The following is a small series of tips for the design and installation of public address systems and emergency broadcast systems. Let's share with you:
Public Broadcasting System Design Tips:
(1) Transmission mode: The output power feeding mode of the system adopts cable broadcast transmission mode.
(2) Line attenuation requirements: In the public address system, the line attenuation from the output of the power amplifier equipment to the farthest user speaker on the line should meet the following requirements:
· Service broadcast should not exceed 2 decibels (at 1 kHz)
· Service broadcast should not exceed 1 decibel (at 1 kHz)
(3) Feed line with constant voltage output, the output voltage is 70V or 100V.
(4) Calculation method of power amplifier capacity:
Calculation methods for operational broadcast systems and operational broadcast systems:
P=K1×K2×ΣPo
Where: P--power amplifier output total electric power (W);
Po--Ki×Pi, the maximum electric power (W) when each sub-channel is broadcast simultaneously;
Pi--the rated capacity of the user equipment of the i-th branch;
Ki--the ith branch requires a coefficient at the same time;
In the case of service broadcasting, each set of Ki in the room program is 0.2-0.4;
Background music program Ki takes 0.7-0.8
K1--line attenuation compensation coefficient: 1.26 when the line attenuation is 1dB;
When the line attenuation is 2dB, take 1.58;
K2--aging coefficient, generally taking 1.2-1.4;
· Calculation method of fire accident broadcasting system:
There are two ways to calculate the system:
a. The power amplifier capacity is determined by 1.3 times the total number of speakers in the system.
b. The power amplifier capacity is determined by 1.5 times the total number of the largest 3-layer speakers in the system.
(5) The power amplifier of the standby public address system of the power amplifier should be provided with a backup power amplifier, which can be automatically or manually used when the working power amplifier fails. Power amplifiers for important broadcasts (such as power amplifiers for fire accident broadcasts) should have their standby power amplifiers ready for immediate use in the event of a malfunction of the operating amplifier. The number of spare power amplifiers should be determined based on the capacity of the important broadcast load.
(6) Speaker settings
• Set up a 3W speaker box in the office, living room, locker room, etc.
· Floor corridors generally use ceiling-mounted speakers, and the spacing of the speakers is considered to be about 2.5 times the height of the floor (the height of the ceiling). Choose 3-5W ceiling speaker.
· 3-6W speaker box should be installed in the entrance hall, general meeting room, restaurant, shopping mall, entertainment place, etc.
· 1W-2W speaker is used in the bedside control cabinet.
· In the case of building decoration and room height allowance, sound column or combination speaker should be used for large space.
• When setting up the speaker in a noisy, humid place, use a horn speaker. The sound pressure level of the horn loudspeaker selected in a place with high noise should be 10-15 dB greater than the ambient noise.
(7) Power supply requirements for broadcasting systems
· The small-capacity broadcasting station can be directly powered by the socket; when the capacity is above 500W, the broadcast control room is set, and the power supply can be supplied by the nearest power controller dedicated line.
· The AC voltage offset value should not be greater than +10%. When the voltage offset cannot meet the requirements of the equipment, an automatic voltage regulator should be installed near the equipment.
· The AC power supply capacity for broadcasting is generally 1.5-2 times the AC power consumption capacity of the final broadcast equipment.
· Fire accident broadcast equipment uses fire power.
(8) Choice of transmission cable · Room service broadcast line should use copper core multi-core cable or copper core plastic stranded wire.
· Other broadcast lines should use copper core plastic stranded wire. • Shielded lines should be used for various program signal lines.
· Fire-fighting accident broadcast lines should use flame-retardant copper core cable or fire-resistant copper core wire and cable.
(9) Laying method of the line • The line shall be laid with steel pipe or wire trough, and shall not be laid in the same line as the lighting and power lines.
· Fire alarm protection measures should be taken for fire accident broadcast lines.
Emergency Broadcast System Design Tips:
(1) The setting of the fire accident broadcast speaker should meet the following requirements:
• Emergency broadcast speakers should be placed in public places such as walkways, halls, restaurants, etc., and the number should be such that the walking distance from any part of the floor to the nearest speaker is no more than 25 meters. Speakers should be placed at the intersection of the walkway and at the corner. The last speaker at the end of the walkway is no more than 12 meters from the wall. The rated power of each speaker should not be less than 3W.
· The speaker power in the room should not be less than 1W.
· Speakers with background noise in air-conditioned machine rooms, ventilation rooms, laundry rooms, entertainment venues and parking garages. The sound pressure level of the farthest playback in the playback range should be 15dB higher than the background noise, and the speaker should be determined accordingly. power.
(2) The fire alarm broadcast feeder voltage should not be greater than 100V. The feeder isolation voltage is set on each floor to ensure that when any of the branches is faulty, the normal broadcast of other branches should not be affected.
(3) The fire accident broadcast output shunt shall be controlled according to the evacuation order. The floor control procedure for playing the evacuation command is as follows:
• In the event of a fire on the N and N floors, the upper and lower floors of the fire layer should be connected first.
· In case of fire on the first floor, the floor, the second floor and the underground floor should be connected first.
· In case of fire in the basement, the underground floor and the first floor should be connected first.
(4) When a fire accident broadcast is used in conjunction with a service broadcast or a commercial broadcast, the following requirements shall be met:
· In the fire control room, the speaker and corresponding power amplifier of the fire evacuation layer should be forcibly transferred to the fire accident broadcast state.
· The fire control room should be able to monitor the working status of the fire amplifier.
· Speakers should be installed in the bedside table of the room and should have a fire broadcast function.
• If the fire accident broadcast is combined with a service broadcast or a commercial broadcast with a volume switch, the system should use a three-wire system to force the fire to be broadcast.
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