Tips for installing public broadcasting
Business: Automated Broadcast Broadcast Speaker Family Background Music
As a system of public broadcasting, the influence of various factors on the system must be taken into consideration in the design. Therefore, on the basis of selecting excellent electro-acoustic equipment, careful system tuning and sound sounding conditions can be achieved through careful system design in order to achieve sound and natural sound effects. The following small editors have put together some tips for the design and installation of public address systems and emergency broadcast systems to share with you:
Public broadcasting system design tips:
(1) Transmission mode: The system's output power feeding method adopts cable broadcast transmission mode.
(2) Line loss requirements: In public broadcasting systems, the attenuation of the line from the output of the power amplifier equipment to the farthest user speaker on the line should meet the following requirements:
· Business broadcasting should not exceed 2dB (at 1kHz)
· Service broadcasts should not be greater than 1 dB (at 1 kHz)
(3) Feed line with constant voltage output, output voltage is 70V or 100V.
(4) Capacity calculation method of power amplifier:
Calculation method for operational broadcast system and operational broadcast system: P=K1×K2×ΣPo
Where: P--power amplifier output total electric power (W);
Po--Ki×Pi, the maximum electric power (W) at the same time when each branch is broadcast;
Pi - the user equipment rating of the i-th split;
Ki - the coefficient of the ith branch needs at the same time;
For service broadcasting, the room program uses 0.2-0.4 for each set of Ki;
Background music program Ki takes 0.7-0.8
K1-line loss compensation factor: 1.26 when the line loss is 1dB; 1.58 when the line loss is 2dB;
K2-- aging coefficient, generally take 1.2-1.4;
· Calculation method for fire accident broadcasting system: The system calculation method has the following two methods:
a. 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 loudspeakers in the system.
(5) The power amplifier of the standby public broadcasting system of the power amplifier should be provided with a backup power amplifier. The power amplifier can be automatically or manually put into use when the operational power amplifier fails. Power amplifiers used for important broadcasts, such as power amplifiers for fire accident broadcasts, should have standby power amplifiers that can be used immediately when the operational amplifier fails. The number of spare power amplifiers should be determined based on the capacity of the important broadcast payload.
(6) Setting up the speaker • Set up a 3W speaker box in the office, living room, changing room, etc.
· Floor-mounted hallways generally use ceiling-mounted speakers. The distance between the speakers is about 2.5 times the floor height (ceiling height). Use 3-5W ceiling speaker.
• 3-6W speaker boxes should be installed in halls, general meeting rooms, restaurants, shopping malls, and entertainment venues.
· The 1W-2W speaker is used for the bedside control cabinet in the room.
· In the case of architectural decoration and room net height, sound column or combination speaker should be used for large space.
• Horn loudspeakers should be used when setting up speakers in high-noise, damp locations. The horn loudspeakers selected for use in high noise locations should have a sound pressure level 10-15 dB greater than the ambient noise.
(7) Power supply requirements of the broadcasting system • The broadcasting station with small capacity can be directly powered by the outlet; when the capacity is above 500W, the broadcasting control room is set, and the power supply can be powered by the nearest dedicated power controller.
• The AC voltage offset should not be greater than +10% in general. When the voltage offset does not meet the equipment's limit, 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 of the final broadcasting equipment.
Fire alarm equipment uses fire power.
(8) The choice of transmission cable · Room service broadcast lines should use copper core multi-core cable or copper plastic stranded wire.
• Copper-core plastic twisted wires are preferred for other broadcast circuits.
• Various program signal lines should be shielded.
• Flame-retardant copper core cables or fire-resistant copper core wire and cable should be used for fire accident broadcast lines.
(9) Laying method of the line • The line shall be laid with steel pipe or trunking, and shall not be laid with the same slot as the lighting and power lines.
Fire protection measures should be taken for fire accident radio lines.
Emergency Broadcast System Design Tips:
(1) The setting of the fire accident broadcast speaker should meet the following requirements:
• The emergency broadcast speakers should be installed in public areas such as aisles, halls, restaurants, etc. The number should be such that the walking distance from any part of this floor to the nearest speaker does not exceed 25 meters. Loudspeakers should be installed at intersections and bends. The last speaker at the end of the walkway was no more than 12 meters from the wall. The rated power of each speaker should not be less than 3W.
· In-room speaker power should not be less than 1W.
· Loudspeakers located in air-conditioned rooms, ventilation rooms, laundry rooms, entertainment venues, parking garages, etc. have a background noise level. The farthest playing sound pressure level in the playback range should be higher than the background noise level by 15 dB, and thus determine the loudness of the loudspeakers. power.
(2) The fire accident broadcast feeder voltage should not exceed 100V. The feeder isolation voltage is set on each floor to ensure that when any branch fails, it should not affect the normal broadcasting of other branches.
(3) The fire accident radio output shunt should be controlled according to the evacuation sequence. The floor control procedure for playing evacuation instructions is as follows:
· Fires on floors N and above must be connected to the adjacent upper and lower fire floors.
• If there is a fire on the first floor, this floor, the second floor and the underground floor should be connected first.
• Fires in the basement should be connected to the underground floors and the first floor.
(4) When the fire accident broadcast is combined with service broadcast or operational broadcast, the following requirements shall be met:
• In the event of a fire, the fire evacuation layer speakers and corresponding amplifiers should be forced into the fire accident broadcast state in the fire control room.
• The fire control room should be able to monitor the working status of the fire accident radio amplifier.
• The speakers in the nightstands of the rooms should have a fire broadcast function.
• If the speaker for fire accident broadcasting and service broadcasting or service broadcasting is equipped with a volume switch, the system shall use a three-wire wiring to forcibly open the fire.