Acoustical Layering: A Recipe for Quality Sound

Acoustical Layering: A Recipe for Quality Sound
Basically, a recipe is a list of ingredients and directions. We found a RECIPE that works for sound! But, it takes more than a good recipe to make a great meal or dessert. For the best results, you need the best ingredients and the best directions possible. You also have to understand the expectations of those who are going to taste the results of your effort. For example, a chef may like extra spicy food. But, when preparing food for others, s/he must take into consideration the guests s/he will be serving. The chef may need to vary the recipe slightly.



Figure 1


THE INGREDIENTS:

If a recipe calls for cream, it's not essential to use Alpine milk from hand-milked Bavarian cows. But, if you try to use skim milk instead of cream, you may jeopardize the final results. The same holds true for sound reinforcement. A microphone designed for hand-held vocals used as a pulpit microphone simply isn't the ingredient for the recipe - it won't create the best results.

Here is a list of ingredients (* indicates optional ingredients) for your sound system:

* Well-Designed, Properly Installed Main Speaker System
* Quality Microphones for Speech
* Quality Microphones for Music Vocals
* High Quality Microphones and Direct Boxes for Musical Instruments
* Low-Noise Main Mixer with Sufficient Inputs and Outputs, Gain and Headroom
* Quality Equalizer(s) of the Right Type and Configuration
* Well-Built, Well-Maintained Cables
* * Quality Monitor Speakers
* * Quality Playback Cassette Decks and CD Players
* And, the Icing for the Cake


THE DIRECTIONS FOR A GREAT MIX:

Let's start with the basics (eggs, flour, milk. . .):

It is vital to understand the acoustical elements of the sound mix and their effect on each other. Take a look at the following multilayer cake. It represents the concept that each ingredient builds on the other and they all work together to create a desired outcome. It should be pointed out that you may not use all these layers. However, the principals remain the same.

The bottom layer (ambient noise) is already established for you. The amount of ambient noise in the room establishes the base layer of sound. In other words, the air system, conversations, babies crying, people moving, etc. creates noise the sound system must overcome. The ambient noise will also change levels. For example, an empty room is much quieter than one filled with people.

The second layer is acoustical instruments. It is important to begin first with the organ, next add the piano, then add the drums, and finally add any other acoustical instruments. For example, if the two main instruments are organ and piano, begin with the organist playing a selection. Have the pianist join after the first verse. If you have trouble hearing the piano, open the piano to "full stick" and reposition it so the open lid is facing the congregation. (Upright piano: face the back sound board toward the congregation.) If the piano is still not loud enough, then a reinforcement microphone will need to be added.

Please note, we advise natural acoustical solutions before adding sound reinforcement.

If you use drums during a service, test them next. Have the piano begin playing. Then begin the drummer after a minute or two. Listen first to determine if you can still hear the piano (hint: the higher octaves of the piano are usually easier to hear over other instruments). If the piano starts to get buried, increase the microphone level on the piano gradually. Again, try natural solutions before adding microphones or raising volumes. Perhaps the drummer or organist can play softer. Finally, test any other acoustical instruments including acoustical guitar, woodwinds and brass.

The third level is made up of electronic instruments such as keyboards, electric guitars, bass guitars, acoustic instruments with electronic pickups, electronic drums, etc. The piano is usually the primary acoustical instrument, and you have already set the piano level. Now add any electronic keyboards to the mix. At this point, you can have the drummer and other acoustic musicians take five. Use the same procedure as before. Begin with piano and add one keyboard at a time. Then continue with any other electronic instruments. When you have finished, take a break. Try to leave the room and listen to silence for five minutes. Then go back and listen to the whole instrumental mix.

Last, but certainly not least, are the vocals. Beginning with the background vocals, add each vocalist one at a time as you did the instruments. Finally add the primary vocalists. Obviously, it is vital that the primary vocalist(s) are heard and understood above all the other instruments and background vocals.


A PERSONALIZED TOUCH:

As in our example of the chef varying the recipe slightly; you, as the sound operator, may need to vary this recipe slightly. You know what your congregation likes to hear. Also, you know which specific instruments will be used in your situation. So, if you would like the background vocalist to be as pronounced as the primary vocalist, add your personalized touch!


A FEW TIPS FROM THE CHEF:

1) Always listen for what is too loud as well as what is too soft.

2) If a musician or vocalist says s/he needs more of themselves in the monitors, first think of turning other instruments or vocals down ...just a bit. Ask them what is too loud.

3) Always make level changes to the monitor mix or channel gain trim control when the musician or vocalist is not active.

4) Make small, gradual changes.

5) Occasionally turn down the master levels for the main sound system and listen to the monitor system to see how loud it is. The monitor system may be causing the main system to sound poor. Also, walk to the first few pews to see if you hear more sound from the monitors than the main system.


A FINAL WORD:

Communicate with the ministry team. Let them know this recipe may take several attempts before creating a cake that deserves icing. It will take extra time, effort and patience on everybody's part. But the results will be worth it!

OPERATION HINTS

Gain Trim Hint: Use this method when first setting up a mixer channel. Before you begin to bring the volume control up (fader) on a channel, make certain the channel gain trim control (usually located at the top of the channel) is turned completely down (counterclockwise). Also make certain the master output (and subgroup) faders are set at a normal operating position (check your mixer manual if you aren't sure about this). THEN, set the channel fader at a nominal position (usually 2/3 or 3/4 of the overall fader travel). NEXT, bring up the channel gain trim control slowly until you have a decent level.

Monitor Level Hint: Adjust the main level first, then add monitors. Follow this simple rule of thumb: When "adding" an instrument or vocal to the sound reinforcement mix, make certain the monitor speakers are off. After you have established a good level in the main system, gradually bring up the monitor mix(es). This way, the vocalist or musician will usually require less monitor level since they also hear themselves in the room.

Channel Equalizer Hint: Level first, equalizer last! When you begin to setup your initial mix levels, make certain the tone/equalizer (EQ) controls on each channel are turned back to zero (or bypassed if the mixer has an EQ bypass switch). Add EQ changes ONLY after you have finished your initial mix level settings. Use the EQ to blend or highlight instruments and voices. This takes time and practice. Done right, proper EQ can make a dramatic difference in the overall mix.

Drum Hint: If you use drums, there are two reasons you may want to consider constructing or purchasing portable isolation panels to surround the drums. First, the other musicians and vocalists will hear less drum level on the platform. Secondly, the sound mixing technician will have more control of the drum levels AND will usually be able to reduce the overall sound level.

by Travis Ludwig
< Back

Feedback

One of the most common complaints we hear from people concerning their sound system is, “I can’t get enough volume before I hear a loud ‘tone,’ ‘squeal,’ ‘whistle’ or ‘noise.” What they describe is feedback—in sound system jargon.

When Feedback Occurs

Feedback can occur when you have a microphone, a loudspeaker and a path between the two. A person talks into the microphone and the sound is converted into a tiny electrical signal. It is magnified many times by the amplifier and then sent to the loudspeaker. The large electrical signal is converted back into sound that is louder than the original. The amount of amplification is called the gain of the system. As the gain of the system is increased, the loudspeaker will put more and more acoustic energy into the room. This energy bounces around the room. Some is reflected back into the microphone and is amplified again. As the gain of the amplifier is increased, the level the microphone picks up from the loudspeaker is increased. At some point, the level the microphone receives from the talker and the loudspeaker will be the same. This is unity gain. If we increase the gain any more, we will hear a tone- feedback. The system is going into oscillation, and it can build up so loud that the system will self-destruct if the gain is not decreased.

Figure 1
Positioning greatly affects gain before feedback.

More Gain and Less Feedback

Now you may ask, “How can I get more gain before feedback?”

The distance between the loudspeaker and the microphone determines the maximum absolute acoustic gain, Figure 1. Decrease this distance and you will decrease the absolute gain. Increasing this distance means the sound from the loudspeaker must travel a greater distance. That means an increase in the absolute acoustic gain.

But what if you can’t move the loudspeaker or the microphone? It is possible to increase the apparent acoustic gain without changing the absolute gain.

Have the talker move closer to the microphone. The microphone now receives a louder signal; in turn, the loudspeaker will reproduce a louder signal without increasing the gain of the amplifier.

Move the listener closer to the loudspeaker. The sound will appear to the audience to be louder.
Other Factors and Components Affecting Feedback

There are other factors that ensure your system is capable of achieving its maximum absolute acoustic gain. First, you must have high quality components. For instance, the microphone must have a flat frequency response. In other words, it should pick up all the different pitches or frequencies identically. If the microphone is more sensitive at a particular frequency, then the system will tend to feedback at that frequency. The same is true for loudspeakers. They must be able to reproduce each frequency identically or feedback will occur at those frequencies which are higher in level.

An equalizer can help by cutting certain frequencies. Let’s say a particular microphone has a peak in its response at 6000 Hz and feedback is occurring at that frequency. An equalizer can electronically cut the response of the loudspeaker system at 6000 Hz. The total system response curve has been flattened and the gain can be increased until we hear feedback at another frequency. Careful adjustment can often achieve considerably more gain in a sound system.


Figure 2
Digital automatic feedback controller.

A relatively new type of equalizer is the digital automatic feedback controller, Figure 2. These units sense feedback and insert a very narrow filter on the offending frequency. It is really a parametric equalizer that is set automatically. Some units are now available that have both a computer based multi-channel parametric or 1/3 octave band equalizer in addition to the automatic feedback filters. These are powerful tools when used correctly.

A word of caution:
An equalizer can do (and often does) more harm than good if it is improperly adjusted. It takes testing equipment and prudent use to realize the maximum benefit from an equalizer. Also, please note, an octave equalizer is ineffective to reduce feedback because it affects so many frequencies at once. A 1/3 octave band or parametric equalizer must be used.

There are other factors that also affect the available gain. For example, loudspeaker directivity (pattern), the room acoustics, reflections, the pickup pattern of the microphone, and the number of microphones that are on will all influence the system’s available gain.

Summary

Briefly, to increase your system’s gain: One, separate the loudspeaker and microphone as much as is practical (but no more than 45 feet). Two, use high quality components. Be sure to have them adjusted and tuned properly. Three, only the microphone(s) being used should be turned on. Remember, less is usually better. And four, be sure the talker is close enough to the microphone to assure a feedback-free system.

ron huisinga

On " ATTITUDE"......

“The longer I live, the more I realize the impact of attitude on life. Attitude, to me, is more important than facts. It is more important than the past, the education, the money, than circumstances, than failure, than successes, than what other people think or say or do. It is more important than appearance, giftedness or skill. It will make or break a company... a church... a home. The remarkable thing is we have a
choice everyday regarding the attitude we will embrace for that day. We cannot change our past... we cannot change the fact that people will act in a certain way. We cannot change the inevitable. The only thing we can do is play on the one string we have, and that is our attitude. I am convinced that life is 10% what happens to me and 90% of how I react to it. And so it is with you... we are in charge of our Attitudes.” Charles R. Swindoll

Light and Sound Decision

Microphones: Mystery Solved

There are many microphone mysteries. Many users do not really understand how they work and why some microphones work better for certain applications. The microphone facts in this article will help you better use your microphones.

The vacuum cleaner myth

Many people feel that microphones are like vacuum cleaners. The microphone is mounted on a stand and it "sucks" in sound. Better microphones have more suction so they pick up sounds from farther away. The term "reach" is often heard. One microphone is said to have better reach than another.

However, microphones are not like vacuum cleaners. They only sit at a point in space and measure (pick up) what happens to the change in air pressure at that particular point. The air pressure changes when someone talks, sings or plays an instrument. Of course, the microphone will also pick up unwanted pressure changes from airplanes flying over the church or babies crying in the church. The vocal cords of the baby produce changes in the air pressure which emanates from the baby's mouth. The sound waves are like the ripples produced from a rock thrown into a smooth pond. The ripples move out from a central point where the rock first hit the water. As the ripples travel outward, they gradually get weaker and weaker until the water is smooth again.

The microphone measures the tiny changes in air pressure. This change is converted into a tiny electrical voltage by the microphone transducer. Therefore, one particular microphone will not naturally "pick up" better than another at a certain distance. There are other factors which may make one microphone appear to work better.

Common Types of Microphones


Figure 1

The dynamic microphone (Figure 1) is the most common type of modern microphone. It has three basic parts: the diaphragm, coil, and magnet. The diaphragm is a very light dome-shaped form. A coil of very thin wire is attached to the rear of the diaphragm. The coil is positioned so a magnetic field surrounds it. A change in air pressure causes the diaphragm and coil to move. The coil movement within the magnetic field produces a tiny voltage in the coil. This tiny voltage is sent down the microphone cable to an amplifier in the microphone mixer.

Figure 2

The other major type of microphone transducer is the capacitance or electret microphone (Figure 2). This type has a diaphragm like the dynamic microphone. However, it does not use a coil and magnet. Instead, the diaphragm is actually a capacitor (it has the ability to store and release electricity). When air pressure moves the diaphragm of this microphone, the distance between the diaphragm and the back plate changes. This produces a change in capacitance which is converted to an electrical voltage which is sent to the amplifier. Power must be provided for the capacitance microphone since it utilizes some electronics. Power can be furnished by a battery or from the mixer itself. This type of power is usually called phantom power since the power from the mixer uses the same wires the tiny audio voltage travels along.

Capacitance microphones have traditionally been more sensitive than dynamic microphones. In other words, for the same change in air pressure, the capacitance microphone will produce a greater voltage. This advantage has become less distinct as better magnets in dynamic microphones have produced higher outputs.

Microphone placement

Let's go back to the analogy of the rock and ripples. The ripples are the strongest or highest at the point of impact. As they radiate from the center, they become weaker at any particular point. This is the same way sound waves travel. The sound pressure level is called the SPL for short. The SPL will decrease by 6 dB every time the distance from the sound source doubles. A 10 dB decrease would seem as though the sound level dropped in half. A 3 dB drop is barely perceived. The 6 dB drop is about a quarter drop in perceived level to your ears.

Figure 3
How is this fact used in real applications or microphone techniques? Let's say a talker places a microphone 1" from his mouth (see Figure 3). The microphone is mounted on a gooseneck which is attached to the pulpit. If the talker moves away another 1" he will have doubled the distance from the microphone, so the SPL reaching the microphone will have dropped 6 dB. If he now moves back another 2 inches, the distance will have doubled again, so the SPL will be down a total of 12 dB. The sound level from the sound system will have apparently dropped in half. If the listener could hear the talker just right when the talker was at the 1" position, he will probably not hear very well after the talker moved back only 3". It would be very easy for a talker to move this much while speaking. The result would be wildly varying volumes for the listener.

What if the talker started at a position of one foot from the microphone. Moving to the two foot mark would produce only a 6 dB drop in level. The talker would have to move another 2 feet for a total of 4 feet to get to the 12 dB level drop. In other words, natural movement would not be very audible if the talker started at the 1 foot position.

Maximum gain-before-feedback

What can be done if the volume is not loud enough before that annoying feedback occurs? There are two things which can be adjusted before deciding to order new microphones or change the sound system.

The absolute gain of your sound system is primarily set by the physical distance between the speaker system and the microphone. The absolute gain is the maximum gain in volume you can achieve before feedback occurs. The actual absolute gain can be influenced by high quality equipment and proper design, installation, and positioning of the equipment. If the sound system is operated at a level below the absolute gain, feedback will not occur whether the talker whispers or shouts. The sound system is said to be stable. Increasing the gain by turning up the volume control on the mixer will eventually exceed the absolute available gain and feedback will be heard. Since we do not want to hear feedback, the only option is to turn down the volume control, which decreases the system gain, until the feedback stops. However, the talker may not be loud enough for easy listening. There are two methods which can increase the volume.

The first method is to have the talker speak louder. When the talker speaks louder, the microphone will pick up a louder signal and that will be amplified louder. Too often, the natural reaction of a talker to hearing feedback is to talk softer. That is exactly opposite of what should happen. The talker needs to talk louder so the sound system gain can be turned down.

If the talker can't speak louder, they then need to get closer to the microphone. Remember the ripple example? The sound level reaching the microphone will be louder if the talker moves closer. The sound system gain or volume has not been adjusted, but the signal entering it has increased in volume. The result is a louder volume from the speaker system and the listener can hear better.


Figure 4
4 ways to maximize
gain-before-feedback:
Move the microphone closer to the talker (decrease DS).
Have the talker speak louder.
Move the loudspeaker closer to the listener (decrease D2).
Move the microphone further from the loudspeaker (increase D1).

Summary

Using these basic microphone facts will help you better understand how to get the most out of your present equipment.

Ron Huisinga

Microphones: Praise & Worship Techniques

Worship styles, regardless of denomination, demand a lot from the sound system. In praise and worship, the vocal microphones are very important. If the vocals can't be heard, the congregation has difficulty following the worship service. So how can the vocal quality be maximized? The microphone selection and placement work together to maximize vocal quality.


Microphone Selection

It's a good idea to know the microphone's characteristics before you select the vocal microphones.

Most microphones can be sorted into two generalized categories: close-proximity and distant-use (ensemble) microphones.

Figure 1
Close-Proximity Microphones are usually distinguished by the ball-shaped grille (see Figure 2). They are usually designed with a low-frequency roll-off to compensate for proximity effect (as shown in Figure 1). When most directional microphones are used within 12" of the sound source, the bass is louder.

One special-use, close-proximity microphone, is the headset. These microphones provide clean, natural sound without having to hold a microphone. They are comfortable and can be worn with most hairstyles.

Figure 2
Distant Use (Ensemble) Microphones usually have a small grille. And, the handle or barrel is narrow. Again, see Figure 2. Why is it important to know what type of microphone to select? If you place a Close-Proximity microphone 2 or 3 feet from a vocalist, the sound will lack bass frequencies. The ensemble microphone will sound much better at a distance, because it has a more even flat bass response.

Microphone Placement Methods

Close-Proximity
It is best to use one close-proximity microphone per vocalist. However, it isn't always realistic for a church to have that many microphones on-hand all the time - not to mention, the number of inputs your mixer has. Also, to achieve the most similar output characteristics, it is wise to use the same model of microphone for every vocalist.

Figure 3
You can also use a close-proximity microphone for every two vocalists by following these suggestions:

Mount the microphone on a stand. Two vocalists can easily center themselves side-by-side when the microphone is on a stand (see Figure 3). Vocalists have a tendency to hold the microphone closer to themselves if they hold it in their hand.
Position the two vocalists so they are cross-focused (again, see Figure 3). This will keep the vocalists from moving out of the microphone's pick-up pattern and will maintain a uniform level from each.
If possible, have two similar voices on one microphone, such as two sopranos or altos.
The lead vocalist should still have their own microphone.
Distant-Use (Ensemble)

If it's necessary to use one microphone for three or more vocalists, use a Distant-Use microphone.

Position the vocalists far enough from the microphone so they are within the pick-up pattern.

Figure 4
To help picture a microphone's pick-up pattern, imagine a flashlight with an adjustable beam. "But I can see the flashlight beam. How can I hear the microphone's pattern?" Here's a simple trick. While listening through headphones, have someone sing (and hold) a single note. At the same time rotate the microphone from center (on-axis) to left or right (see Figure 4). Make sure the distance between the microphone grille and vocalist doesn't change. You will notice the level drop. This will enable you to HEAR the pattern of the microphone.

Figure 5
A cardiod directional vocal microphone will have an approximate 130 degree cone-like coverage pattern (see Figure 5).

A Final Note

As the sound operator, you are part of the worship team. You have the power to make or break a long rehearsed worship song. With that power comes responsibility - it needs to be taken seriously.

Travis Ludwig

How To Lead Worship You Can Be Proud Of

Being a praise and worship leader is likely one of the most satisfying and wonderful tasks in the church. But if pride comes before a fall, then worship leaders are recognized with pastors is among the most prideful folks in the church immediately! Is it flawed to be proud of your worship leading? Is it unsuitable to be pleased with your talents? Is it wrong to learn to lead worship extra effectively?

As a praise and worship leader for over 20 years, I've usually wrestled with the concept of pride. The primary remark to make is that I believe my ability and your skill as a worship leader is God-given, and it isn't an inherent or discovered capability or talent that we now have developed in ourselves. Sure, we may be nice musicians, wonderful guitarists or fabulous Keyboard gamers, however merely having musical means doesn't make you an incredible worship leader. We'd have a wonderful voice, one which we have now worked on diligently for a few years, however this doesn't make you an amazing worship leader.

However, when God takes his natural capability or talent, He and He alone can remodel an amazing musician or singer into an anointed praise and worship leader. It doesn't matter what your ability level, we have to recognise that being an anointed worship leader is a small quantity about our skill, and nearly completely about the anointing of the Lord! Whenever you keep this attitude on praise and worship leading it is hard for the heart to be overcome with a sinful pride.

In order a praise and worship leader, when I think about worship leading that I will be happy with, it is really a measure of satisfaction that I've understanding that it has been a job well performed, and that myself and my team have led the people right into a deeper presence of the Lord. It isn't pride in my abilities, and even figuring out how to lead worship successfully, is that feeling of satisfaction knowing that I've set out to serve the Lord and, by his grace, he has seen me by to the tip and has blessed my efforts and the efforts of my crew with powerful and positive results.

lights and sound

Renting Mobile Lights and Sound for a Party

Throwing a really memorable party takes some foresight and a few bucks. You can't scrimp on the budget to earn a solid party rep. You need good music, live or on disc, doesn't really matter if the sound is great. Good food and fun people can make or break your party. The drinks and supplies should be plentiful. Rent a brilliant mobile lights and sound setup to round it all out.

1.Check out the room or the building where you will hold your party to make a plan. Decide what kind of lighting and sound you want, where it will be set up and who will run the systems.

2.Ask the band or the disc jockey if they supply any of their own sound system supplies. You don't want to rent pieces that are already included in the DJ package. The band may need you to rent microphones, but carry their own amps. Don't assume they have everything they need and don't rent supplies you won't use.

3.Find a business that rents everything. A one-stop party outlet can save you time running around and working out delivery schedules. Sometimes you can work a better deal when you rent more than one system. Try to get all your supplies from the same outfit.

4.Read the contract before you sign. Look for small print where extra charges are often hidden. Some party supply companies charge huge late fees, while others don't have any insurance written in their package.

5.Use a professional or friend who knows how to run the equipment. Renting sound and lighting for a party is going to cost you enough, you don't want to end up buying the stuff just because someone inexperienced ruined the equipment.

6.Keep partygoers away from the rented equipment. Often, drunks think they know how to run expensive sound and lighting equipment and wind up creating havoc and accidents. Be clear to your guests that the equipment has a designated operator.

eHow Contributing Writer