PUBLIC ADDRESS SYSTEMS

1. Practical-4
Public Address Systems
Like any sound reinforcement system, a PA system – or Public Address system –
has three components:
 A pickup device (such as a microphone) to convert sound waves into an
electronic signal
 An amplifier to boostthe weak signal produced bythe pickup to a level that
can power a speaker
 A loudspeaker to convert the electrical impulse from the amplifier back into
sound waves
Manufacturers create PA systems by putting together components of comparable
quality and price in one convenient configuration.
While this is convenient and ensures the proper matching of components
(amplifiers to speakers for example), such PA system packages can at best
approximate user needs rather than fit exact specifications.
That said, there are so many different types of PA systems that most people can,
with a little care, select a PA which is a pretty good fit for their needs.
The following 6 principles – what we at AudioLink call the 6 “P’s”ofPA selection
– can take the guesswork out of getting the right PA system for your sound
reinforcement needs.
Let us discuss the 6 P’s in detail:
1) Powerrequirements
2) Purpose of your PA system
3) Prestige events
4) Portability of a PA system
5) Potentialfor expanding PA System
6) Price

2. 1) Powerrequirements increase for largeraudiences or noisy
environments:
Power is the chief consideration when choosing a PA system.
As the size of an event and audience increases, so do the power requirements. It is
therefore useful to divide PA systems into categories based on their Wattage and
the power of their amplifier.PA systems into are available in broad categories
ranging from just a few Watts up to 500 Watts or more.
Classifying PA systems in these categories is a simple way to broadly identify
systems suitable for audiences of various sizes. In addition to audience size also
consider the physical environment that your PA must serve.
Using the PA system for sound reinforcement at outdoorevents, for example,
sound reflections (and therefore the perceived volume of the PA system) decrease
– and the amount of Wattage need increases. Similarly, an auditorium with high
ceilings requires far more amplification than a small conference room.
A PA system that’s slightly larger than need is more efficient (and sounds better)
than a small system working at close to capacity.
2) The Purpose of your PA systemdrives its requirements:
To amplify music, as well as speech, your PA system requires some additional
capabilities:
Music amplification requires a system that covers a wider range of
audio frequencies than speech. Make sure that the PA system is able to
reproducesound in the high and low ranges as well as the middle range of
the audio spectrum.
Music reproduction requires more wattage. Since music contains a wider
frequency spectrum than speech, power needs for music can be more than
double.

3. Music sounds best in stereo. While a mono system may sound great in the
relatively narrow range of speech, the complexity of music is better served
by natural sounding stereo.
More speakers willmake your music sound better. Most PA systems
designed for music feature individually tuned single speakers put together in
a package to reproducea full frequency range. A good loudspeaker features
a woofer for low frequencies, a tweeter for high frequencies, and a horn for
midrange frequencies.
While these considerations address the basic needs of pre-recorded music (or one
or two musicians), keep in mind that sound systems for musical productions can
become quite large and complex and therefore quite costly. Manufacturers suchas
Fender and Samson offer portable stereo PA systems.
3) Prestige events needa sound systemthat is either unobtrusive (built-
in) or visually pleasing:
A prestigious event demands a different approachto a PA system.
For example, at a formal ceremony a PA system should look the part: a
freestanding podium housing can add dignity to suchoccasions. A built-in PA
system to the housing can have a complete system that both amplifies the speaker’s
voice and graces the occasion.
Freestanding podiums with PA systems boasta wide range of styles to fit a variety
of events.
Acrylic podiums, can lend a high-tech sheen to conferences or other business
events, while a speech by a government official or religious leader can be well-
served by a traditional hardwood podium.
For lecturers using written notes, a laptop, a media player, or a projector, many
podiums feature large reading tables and even fold-out shelves for storage.
Other podium accessories suchas brass reading lamps serve to enhance the
prestige of your presentations even as they add practical features for speakers.

4. 4) The Portability of a PA system is a cost-saving (and back-saving)
feature:
When a PA system will be used in multiple venues portability is a money-saving
feature.
Handles, wheels, and compactcases enhance portability and become increasingly
important in more powerful (heavier) PA systems.
Similarly, as the number of features in a PA system increases to accommodate
more esoteric uses portability suffers. Consider how often will PAS move, and
how far before opting to buy a heavier option-laden PA system.
In many cases where a PA system must be portable, the presenters need to be
mobile as well. In these situations, consider a PA system that supports a wireless
microphone solution. If a speaker needs to also use his/her hands consider a
wireless hands-free microphone such as a lavaliere mic or a headband mic.
Also, if using portable PA system outside or in places without AC power be sure to
get a battery-powered system. Get a battery-powered PA systems with a
rechargeable battery. Battery life of sound reinforcement systems can vary from 8
to 200 hours, so carefully consider the length of event when estimating battery
needs.
5) Considerthe Potentialfor expanding your PA System in the future:
Unless looking for a PA system for a specific ongoing purpose, considerthe
purchase of a package that can grow with your needs. An expandable PA that
eliminates the need to buy a second orthird PA system later on is often your most
budget-friendly choice.
This is a good idea not only for sound productioncompanies, but also for schools
and houses of worship, which often need a sound reinforcement system that will fit
a variety of applications. There are many ways your PA system can be expanded.
Some of these include adding microphones, companion speakers, speaker stands,
and additional cables. In essence you want a PA system with multiple input and out
jacks.
For example, an expandable system should have extra outputs for either active or
passive speakers. You will also need a line output to attach portable digital
recorders or other recording devices. Then too, for multimedia and other

5. presentations involving music, it’s important to have a line input to plug in your
CD or other media player.
In general, a pre-packaged system should include the essentials like cables, speaker
stands, and mic stands but stockup on extras will be adding microphones or
speakers to your PA system later.
6) Price:
Price moves in sync with the features and the power of your system.
Price also increases with enhanced sound quality and the advanced engineering of
components to reduce weight without sacrificing fidelity.
Technicians have identified higher end systems with TOP OF THE LINE and
BEST BUY designations to help you recognize systems which give you a good
return for your money.
It’s important to closely evaluate exact needs before purchasing a feature not likely
to be used. If not sure, pick a system to which features can be added later if
required.
Conclusion: we studied about various uses and applications of PA Systems and
also about the 6 P’s that are to be taken care before selecting PA Systems.