Setting Up Sound Equipment To Get The Best Results
YOUR SOUND SYSTEM: SETTING IT UP TO GET THE BEST RESULTS Before we talk about setting up your sound system. let's talk a bit about what you have to work with.
The amplifier is the heart of the sound system. The music source (phonograph, Laptop, MP3 player, tape, MiniDisc or CD player) generates a feeble electrical current. The diaphragm of the microphone is vibrated by the sound waves of your voice and it also generates a feeble electrical signal. Because they change energy from one form to another they are called transducers. Feel free to use that word any time you want to impress somebody. The amplifier picks up these feeble signals, makes them much stronger, and delivers them to the third transducer in the system, the loudspeaker, which changes the electrical energy back to sound energy again. Unfortunately, it changes only part of the electrical energy to sound; the rest is changed to another form--heat.
When you turn up the music volume control on your amplifier, the music will get louder until you reach a certain point. At that point it begins to get distorted, and the more you turn the knob, the more distorted it will be. You have reached the maximum undistorted output of your amplifier. From that point on, you will get very little more volume and much more distortion. Lesson number one: It is useless to turn up the knobs as far as they will go.
The speaker, as we said, changes electrical energy into sound. The two factors that limit the amount of sound a speaker will produce are its power handling capacity and its efficiency. Every speaker has a point at which applying more amplifier power will not produce any more sound; it just produces distortion which gets worse as more power is applied. This is called overloading, and too much overload can actually damage a speaker. It is quite possible that you could unhook that speaker and plug in another that would produce much more sound, without touching the volume control! The second speaker is more efficient than the first. More energy is turned into sound and less onto heat.
The amount of power that the amplifier delivers is measured in watts. Let's say that you have an amplifier that will deliver 25 watts without distortion, and a speaker that will handle 50 watts without overloading. If only you had a 50 watt amplifier, you could get twice as much sound from that speaker, right? Wrong. To double the sound level from a speaker requires ten times as much power from the amplifier. If you apply twice as much power you will get more sound, but nowhere near twice as much. That's lesson number two.
If you use two speakers instead of one you ought to get twice as much sound, right?. Wrong again. The maximum undistorted output limitation still applies. You will get more sound at the same control knob settings, because you have lowered the impedance. That's another impressive word, which we put in to convince any experts that we know what we're talking about. But anyhow, your amplifier has only so much undistorted output, and dividing it between two speakers isn't going to get you twice as much sound. What you can get, if you set up your speakers correctly, is much better sound distribution. That's lesson number three.
Better sound distribution may well enable you to cover twice as much area as you could with a single speaker. With a single speaker you often have to waste part of your amplifier output by making the sound too loud in the front in order to get it loud enough at the back and sides of the hall.
In setting up your equipment, the most important consideration is where you locate and aim your speakers. A speaker sitting on a stage will cover only a fairly small area of the floor. If you raise it up a few feet, it will probably cover twice as much area with better sound. That's rule number one. Aiming your speakers at the dancers, not at the opposite wall, is rule number two. The sound must pass over the heads of the nearest dancers and reach the farthest dancers without bouncing off the opposite wall. If you can't cover the entire hall with the sound system you have, mark off the area you can cover with chairs or tables so the dancers stay within that area.
Square shaped hall:
One speaker: Place it at the midpoint of one wall: If the sound drops off too much at the sides, try placing it in a corner and see if you can reach the opposite corner with sound. If your speaker is of the open back type, try to place it against a wall. Just as much sound comes out of the back as from the front; if it is against a wall the reflected sound will reinforce the sound on the floor, and if it is very far out from a wall you lose efficiency and may well create an echo. Two speakers: Divide the area in half and use one speaker to cover each half.
Rectangular shaped hall: (length less than twice the width)
A consideration here is that different types of speakers have varying angles of lateral dispersion--the angle at which the sound fans out to the right and the left. Speakers with wide angles of dispersion ordinarily won't cover nearly as far straight ahead as those with narrower, more intense beam of sound.
One speaker: Try setting up at the midpoint of one (narrow) end. If you can't reach the other end, set up at one (wide) side and aim across the shorter dimension. The sound may be thin at the ends, but should be good in the central position of the hall.
Two speakers: In most cases driving across the shorter dimension gives best results. Place speakers so that each covers half the area.
Long, narrow hall:
One speaker: Set up at one (narrow) end. The higher you get your speaker the farther it will reach; if it won't reach the other end, it won't.
Two speakers: If the ceiling is so low that you can't set up at one end and reach the other end, use a long cord and place one speaker at each end of the hall, aimed at each other. Tilt both speakers down at the heads of the dancers at the center of the hall. This will give good sound with no "time lag effect" which would distort the sound at the center. Never set up one speaker at the end and another partway down the hall aimed the same direction as the first. Without sophisticated time delay devices such a setup will have the affect of creating an echo in the back of the hall; this is the same problem caused by excessive reverberation.
Outdoor setups:
These require much more power because there is no sound reinforcement from reflected sound. Aim speakers at trees and shrubbery if possible, never at a flat wall or you will really have an echo. One or two additional speakers are often require outside to keep the coverage even as well as the extra power to push them.
The amplifier is the heart of the sound system. The music source (phonograph, Laptop, MP3 player, tape, MiniDisc or CD player) generates a feeble electrical current. The diaphragm of the microphone is vibrated by the sound waves of your voice and it also generates a feeble electrical signal. Because they change energy from one form to another they are called transducers. Feel free to use that word any time you want to impress somebody. The amplifier picks up these feeble signals, makes them much stronger, and delivers them to the third transducer in the system, the loudspeaker, which changes the electrical energy back to sound energy again. Unfortunately, it changes only part of the electrical energy to sound; the rest is changed to another form--heat.
When you turn up the music volume control on your amplifier, the music will get louder until you reach a certain point. At that point it begins to get distorted, and the more you turn the knob, the more distorted it will be. You have reached the maximum undistorted output of your amplifier. From that point on, you will get very little more volume and much more distortion. Lesson number one: It is useless to turn up the knobs as far as they will go.
The speaker, as we said, changes electrical energy into sound. The two factors that limit the amount of sound a speaker will produce are its power handling capacity and its efficiency. Every speaker has a point at which applying more amplifier power will not produce any more sound; it just produces distortion which gets worse as more power is applied. This is called overloading, and too much overload can actually damage a speaker. It is quite possible that you could unhook that speaker and plug in another that would produce much more sound, without touching the volume control! The second speaker is more efficient than the first. More energy is turned into sound and less onto heat.
The amount of power that the amplifier delivers is measured in watts. Let's say that you have an amplifier that will deliver 25 watts without distortion, and a speaker that will handle 50 watts without overloading. If only you had a 50 watt amplifier, you could get twice as much sound from that speaker, right? Wrong. To double the sound level from a speaker requires ten times as much power from the amplifier. If you apply twice as much power you will get more sound, but nowhere near twice as much. That's lesson number two.
If you use two speakers instead of one you ought to get twice as much sound, right?. Wrong again. The maximum undistorted output limitation still applies. You will get more sound at the same control knob settings, because you have lowered the impedance. That's another impressive word, which we put in to convince any experts that we know what we're talking about. But anyhow, your amplifier has only so much undistorted output, and dividing it between two speakers isn't going to get you twice as much sound. What you can get, if you set up your speakers correctly, is much better sound distribution. That's lesson number three.
Better sound distribution may well enable you to cover twice as much area as you could with a single speaker. With a single speaker you often have to waste part of your amplifier output by making the sound too loud in the front in order to get it loud enough at the back and sides of the hall.
In setting up your equipment, the most important consideration is where you locate and aim your speakers. A speaker sitting on a stage will cover only a fairly small area of the floor. If you raise it up a few feet, it will probably cover twice as much area with better sound. That's rule number one. Aiming your speakers at the dancers, not at the opposite wall, is rule number two. The sound must pass over the heads of the nearest dancers and reach the farthest dancers without bouncing off the opposite wall. If you can't cover the entire hall with the sound system you have, mark off the area you can cover with chairs or tables so the dancers stay within that area.
Square shaped hall:
One speaker: Place it at the midpoint of one wall: If the sound drops off too much at the sides, try placing it in a corner and see if you can reach the opposite corner with sound. If your speaker is of the open back type, try to place it against a wall. Just as much sound comes out of the back as from the front; if it is against a wall the reflected sound will reinforce the sound on the floor, and if it is very far out from a wall you lose efficiency and may well create an echo. Two speakers: Divide the area in half and use one speaker to cover each half.
Rectangular shaped hall: (length less than twice the width)
A consideration here is that different types of speakers have varying angles of lateral dispersion--the angle at which the sound fans out to the right and the left. Speakers with wide angles of dispersion ordinarily won't cover nearly as far straight ahead as those with narrower, more intense beam of sound.
One speaker: Try setting up at the midpoint of one (narrow) end. If you can't reach the other end, set up at one (wide) side and aim across the shorter dimension. The sound may be thin at the ends, but should be good in the central position of the hall.
Two speakers: In most cases driving across the shorter dimension gives best results. Place speakers so that each covers half the area.
Long, narrow hall:
One speaker: Set up at one (narrow) end. The higher you get your speaker the farther it will reach; if it won't reach the other end, it won't.
Two speakers: If the ceiling is so low that you can't set up at one end and reach the other end, use a long cord and place one speaker at each end of the hall, aimed at each other. Tilt both speakers down at the heads of the dancers at the center of the hall. This will give good sound with no "time lag effect" which would distort the sound at the center. Never set up one speaker at the end and another partway down the hall aimed the same direction as the first. Without sophisticated time delay devices such a setup will have the affect of creating an echo in the back of the hall; this is the same problem caused by excessive reverberation.
Outdoor setups:
These require much more power because there is no sound reinforcement from reflected sound. Aim speakers at trees and shrubbery if possible, never at a flat wall or you will really have an echo. One or two additional speakers are often require outside to keep the coverage even as well as the extra power to push them.
