Broadcasting system is mainly used for outdoor stadiums, railway stations, parks, art squares, musical fountains. Service area is characterized by its large area, space is broad. Large background noise.
- They usually provide sound coverage to large areas such as stadiums or small areas such as house gardens (see fig.1).
- They are often used for sporting events, which means a cheering crowd. Therefore, the system must overcome the crowd noise with enough volume.
- They're outdoors; so the listener only hears direct sound (the sound traveling from the speaker directly to the ear).
fig (1): Outdoor sound system in house garden
- An outdoor sound system needs more power or more efficient speakers than an indoor system.
- Sound Reinforcement System required if Outdoor sound must travel more than 25 feet to listener
Outdoor sound System components: see fig.2
This system consists of the three main stages for any other sound system; input, intermediate and output stages which we are previously explained along this course.
fig (2): simple outdoor sound system
For the outdoor sound system, the main devices/equipments in each stage will be:
1- Input stage:
Microphones (wired and wireless types): see fig.3
fig (3): Microphone types
For more information about Microphones, please follow the link.
2- Intermediate stage: see fig.4
The outdoor radio system will use all the intermediate stage devices/equipments described before in the following links:
fig (4): Intermediate stage devices
- Audio mixer
- Mixer amplifier
- Audio amplifier (boosters)
- Monitor unit
- Speaker selector
- Power supply
- Terminal Boards
3- Output stage:
The indoor radio system will use only the following output stage devices/equipments:
a-Loudspeaker: see fig.5
fig (5): Line Array element
Different types of loud speakers are used in this system as Array loud speakers and multiple ways loud speakers.
b- Sub-woofers:see fig.6
fig (6): Sub-woofers
they are loud speakers which are dedicated to the reproduction of low-pitched audio frequencies known as the "bass" which can be controlled to add more sound enhancements
c- Super tweeters:see fig.7
fig (7): Super tweeters
they are loudspeakers designed to produce high audio frequencies, typically from around 2,000 Hz to 20,000 Hz, tweeters can be controlled to add more sound enhancements.
d- HORNS: see fig.8
fig (8): Horns
The horn type of speaker has been popular for outdoor PA use for decades. The typical horn is usually made of metal or polymers and can withstand the elements better than the cone type speaker. They are far more efficient, which means more sound volume at lower wattage. By lowering the power demands made by the speakers, you can reduce both the size and power requirements of your amplifier.
Horn speakers can best be described as “bright” in their sound. The higher frequencies are reproduced very clearly with virtually no bass. The limited frequency response is one reason they are so efficient. They don’t waste energy reproducing the bass frequencies.
A very important point here is that horn speakers typically found in outdoor PA systems are incapable of producing bass. Therefore, a tone control on the amplifier doesn’t accomplish anything except send amplifier energy into never-never land.
The horn speaker is recommended for large groups indoors or outdoors, where intelligibility is important over greater distances.
Effects of environmental factors
The outdoor environmental Factors present unique challenges to sound system designers and installers , such factors can cause the behavior of sound system to be deviated from the designed or predicted.
The main factors affecting sound outdoors are:
The wind can shift the direction of sound waves propagation (see fig.9) making it appears to come from different location and make refraction effects in the sound waves path.
fig (9): Wind Effect
2- Temperature gradient:
The speed of sound is also affected by temperature (see fig.10), sound pass through hot air (because it is less dense) faster than it passes through colder air and for this reason temperature gradients can cause refraction effects in the sound waves path.
fig (10): Temperature gradient Effect
As sound propagates through air, the air absorbs energy from the sound waves, attenuating it. The attenuation of sound in air is affected by the relative humidity. Dry air absorbs far more acoustical energy than moist air does. This is because moist air is less dense than dry air (water vapor weighs less than air).
in the next topic, I will explain the conference system. please, keep following.