Sound Systems: Priority Components

Has the topic of a new sound system come up in meetings lately, but then the conversation revolved around the expense? Many schools would like to improve their sound system but are forced, by the budget, to cut back to a Need List instead of a Wish List.

So, how do you determine priorities? This article is a guide to help you define your sound-system priorities.

A SOUND SYSTEM

Sound systems consist of four basic groups of equipment: 1) Microphones 2) Preamplifier or mixer 3) Amplifier 4) Loudspeakers. First, this article will give some sound system basics, then briefly describe each of these components in relation to a sound system. And finally, the priorities.

Sound is produced by moving air past a vibrating vocal cord or striking a string in a piano. The sound moving through the air is called acoustic energy. However, this energy competes with many other sources of acoustic energy (students moving, coughing, fans, etc.). The sound can be heard better if we either amplify the original sound or move closer to the desired sound. Either method will make the desired sound louder than the competing energy, and we will be able to hear and understand the talker or singer.

Figure 1

COMPONENTS

So what does it take to amplify the original acoustic energy? It first must be turned into another form of energy. This is done by the sound system microphone (Figure 1). The microphone converts the acoustical energy into a very tiny amount of electrical energy. Now we have a form of energy which the sound system can easily work with. This small amount of electrical energy is sent from the microphone to the microphone preamplifier (Figure 2). The preamplifier is located in your mixing board or mixer/amplifier. The preamplifier boosts the level of the microphone’s output. This higher level is called line level. The outputs of the other microphone preamplifiers are then mixed together and sent to the power amplifier. Here, the line level signal is boosted to a loudspeaker level signal. Now the tiny electrical signal has been amplified enough to power a loudspeaker. The loudspeaker will convert the now large electrical signal into acoustical energy. The acoustical energy is hopefully an exact replica of the original, only louder. The energy then travels through the air and enters our ears. We can hear!

Figure 2

As you can see, there are many links in the sound system chain. Each one is important, but are there some more important than others? Let’s look at each and discuss its importance.

PRIORITIZE

Microphone

The first link is the microphone. It is also probably the most important link. This is not the place to skimp. Since the microphone converts the acoustical energy into electrical energy, any fault here will produce inaccurate sound from the loudspeaker. Please note, there is a huge difference between the pick-up quality from a cheap $20.00 microphone and a $200.00 microphone. A poor microphone will make the best…loudspeakers sound bad. Buying high quality microphones for each different application will result in more gain-before-feedback (volume) and better, more accurate sound.

Loudspeakers

The last link is also very important—the loudspeakers. They have to convert the amplified electrical energy signal back into acoustical energy. Not an easy job. It is difficult to build a loudspeaker that will exactly reproduce the original signal. Here again, the higher the quality, the more naturally and accurately the loudspeaker(s) will perform. The loudspeaker(s) should also be selected for your particular needs. Each school has its own unique acoustics which should be considered. Also, the coverage pattern of the loudspeaker(s) needs to fit your particular seating area.

A properly engineered and installed loudspeaker system can provide even coverage with natural sound and high intelligibility.

Electronics

Another link is the electronics. With today’s technology, there aren’t the extremes in sound quality from electronics as from loudspeakers or microphones. The main difference in electronics are in the features available to make your system flexible and/or easy-to-operate. For example: Do you need one or 32 microphone inputs. Do you need an automatic mixer or will an audio person operate the system? These decisions and many others need to be answered before you select a mixer or amplifier.

Accessories

Accessories form another link. These are the items which allow you to fine-tune your system. You could buy effects gear like reverbs or equalizers.

Compressor/limiters are available to help control the level of the system. A cassette deck could be added to record your events. And don’t forget the system for the hearing impaired. It can be difficult to determine just what accessories fit your needs and budget.

by Ron Huisinga © 1996 Internet Sound Institute (www.soundinstitute.com). This article is for personal use only. Any commercial reproduction is not permitted without permission. To obtain permission, contact ISI at hopi@soundinstitute.com

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