PA System Buying Guide

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PA System Buying Guide

PA systems, or public address systems, are systems designed to amplify and deliver sound to all members of a targeted audience, whether in a small venue or a large complex. They are commonly used in live music performances, sporting events, and similar events and functions, both inside and outside.

About PA Systems

There are various basic components to a PA system. These include microphones, audio mixers, processing equipment, amplifiers, loudspeakersmonitors and cables. The type of components needed will depend upon factors such as the audience and venue size.

Choosing a PA System

The type of portable PA system chosen will depend upon various factors, including venue size, audience size, how the audience is arranged, the type of event, number of performers, how many mixing channels and monitors are needed and the access to power supply.

The various components of the PA system will need to be considered with regards to these factors before a decision can be made.

Microphones

There are many different types and styles of microphones, but all work by picking up sound or air pressure and converting this into electrical signals. The electrical signal can then be passed to an audio mixer for further processing.

Live music performances may have many different style of microphone onstage, including hand held microphones, headset microphones, and drum kit microphones. Headset microphones are also frequently used for other types of stage production and by fitness and dance instructors. The other types of microphone include lapel microphones for speeches and presentations, and table microphones for conferences and meetings.

The basic types of microphone include condenser microphones, dynamic microphones and ribbon microphones.

Condenser microphones


 

Condenser microphones, also called capacitor microphones, have a thin membrane known as a diaphragm placed against a backplate. As the diaphragm moves in response to sound, the space between the diaphragm and backplate changes and this produces electrical signals.


 

Advantages of condenser microphones include smoothness of sound and sensitivity. They need to be powered, either by batteries or phantom power supplied by an audio mixer.



 

Dynamic microphones


 

Dynamic microphones use electromagnetic induction to produce sound. A voice coil is placed in a magnetic field provided by a magnet, and attached to a diaphragm. Sound waves move the diaphragm, which moves the coil. This produces electrical current. Several membranes are required to catch all frequencies effectively.


 

Advantages of dynamic microphones include their robust design. They have high gain before feedback, meaning they can be amplified to a large extent without incurring audio feedback. This makes them suitable for stage performances. Dynamic microphones are also resistant to moisture and inexpensive models are widely available.



 

Ribbon microphones


 

Ribbon microphones have a thin wire ribbon positioned between magnet poles. The ribbon moves in response to air pressure and its vibrations produce the electrical signals. Ribbon microphones are bidirectional, and various arrangements are used for different applications.


 

Advantages of ribbon microphones include their smooth, natural sound and ability to catch high frequencies. They can be fragile, though, newer models are typically more robust and durable.



 


Using the most appropriate type and style of microphone in a PA system will result in better quality sound. Research product reviews and descriptions to find the most suitable microphone for the purpose.

Audio Mixers

Audio mixers, or mixing consoles, receive audio signals from microphones into input channels. They then modulate the signals in various ways, for example by adding equalisation, altering volume and adding special effects, to produce the finished sound. A master output signal is then generated which is passed to an amplifier. Audio mixers can also feed monitor speakers.

Considerations when deciding upon an audio mixer include the number of channels available, monitoring capabilities and microphone preamp quality. There are two basic types of audio mixer – analogue mixers and digital mixers. Analogue mixers are cheaper, easier to use and are said to have a more natural sound quality. Digital mixers have greater functionality with regards to processing capability and are also more compact.

Processing Equipment

Further processing equipment can be used alongside audio mixers to provide added capability for modulating sound and adding special effects. Whether this is needed will depend upon the type of event, budget, and individual requirements.

Amplifiers

Amplifiers receive audio signals from mixers and amplify them into larger signals before transmitting them to loudspeakers. The right type of amplifier is required, as it needs to be able to drive the loudspeakers. However, if it has too great a power rating in comparison to the loudspeakers, it could damage the loudspeakers.

Using the most appropriate amplifier will result in better sound and will ensure that the amplifier’s power is not wasted. An amplifier bought together with loudspeakers and other components should be perfectly compatible with them, but always read product descriptions to ensure the amplifier is appropriate for the purpose. Audio mixers sometimes have integral amplifiers, so there is no need to use separate ones. This type of set up is ideal for smaller venues and musicians who need portable equipment.

Loudspeakers

Loudspeakers convert audio signals received from amplifiers back into sound energy and convey this to the targeted audience, basically doing the reverse of microphones. Various different types of loudspeaker are available, and multiple loudspeakers may be used to precisely reproduce different frequencies of sound.

The different types of loudspeaker, or loudspeaker driver as they are more accurately called, are woofers, sub woofers, mid-range and tweeter, each reproducing different sound frequencies.

Woofers


 

Woofers produce low frequency sounds, from around 40 hertz (Hz) to around 1000 kilohertz (kHz). Some woofers handle very low frequencies or mid-range frequencies of around 2000 Hz to 5000 Hz, sometimes negating the need for a sub woofer or mid-range speaker. Woofers that handle mid-range frequencies are sometimes called mid-woofers.



 

Sub woofers


 

Sub woofers produce very low frequency sounds, from around 20 Hz to around 100 Hz, catering for instruments such as bass guitars and kick drums. They tend to have a simple design.



 

Mid-range speakers


 

Mid-range speakers produce middle frequency sounds, from around 300 Hz to around 5000 Hz. This covers a wide spectrum and caters for various instruments as well as vocals. It is also the spectrum which the human ear picks up on most, so having a good quality mid-range speaker is important.



 

Tweeters


 

Tweeters produce high frequency sounds, from around 2000 Hz to around 20000 Hz, catering for vocals and instruments like cymbals.


 


Some loudspeakers have in built amplifiers, so there is no need for separate amplifiers. Important considerations with regards to loudspeakers include their capacity as well as portability, especially if they are to be moved frequently.

Monitors

Monitors are used on stage so that performers can hear themselves. Audio mixers pass audio signals to the monitor via an amplifier, which may be either a separate amplifier or built in. Each performer may have their own monitor but this is not always the case.

Cables

Cables link all the components of a PA system together, so are a vital and integral part of the system. Good quality cables will result in better sound quality and last longer.

Find a Portable PA System on eBay

To find a portable PA system on eBay, go to the home page and scroll over the All Categories tab on the left of the page. This brings up a menu from which Musical Instruments can be selected. From this page click on Pro Audio Equipment. Type “PA system” into the search bar at the top of the page to bring up relevant listings or select required components from the tabs to the left. A search for PA systems and various separate components can also be conducted directly from the eBay home page.

Conclusion

PA systems are used in various events to amplify and deliver sound from its source to a wider audience. Basic components of a PA system include microphones, an audio mixer, processing equipment, amplifiers, loudspeakers, monitors, and cables. Microphones are available in different styles and types, the three basic types being condenser microphones, dynamic microphones and ribbon microphones and different styles including hand held microphones and headsets. Audio mixers are available in analogue and digital models, each with its benefits and drawbacks, though analogue mixers tend to be easier to use and digital mixers have greater functionality. Further processing equipment may be required. Amplifiers amplify the electrical signal received from mixers and pass it to loudspeakers, which reproduce the sound. It is important to have compatible amplifiers and speakers. The different types of loudspeaker include woofers, sub woofers, mid-range speakers and tweeters, each reproducing sound in different frequencies. Other components of a PA system include monitors and cabling. Choosing the best quality components will result in better sound quality and longer lasting equipment.

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