Communication Between The Stage And Sound Booth

When mixing audio at church, or when for example the pianist (being the music director) whants to communicate the drummer, there would be need for a system or issues that may arise to slow down the practice, sound check or even the service. Communication between the soundboard and the stage or between band mates is really important for optimum sound quality and enjoyment. There are different ways to communicate and this article will cover the main basic ones…

Physical Signs

Using body language, hands, pointing fingers and other forms is probably the most distracting and less effective (unless specific signs are worked out between the musicians and sound technicians). So many times the sound tech or director is trying to let a musician know that his guitar isn’t plugged in, or that a vocalist has the incorrect microphone and they are trying everything possible to get attention from the stage. In most cases, all you can do is wait it out; even wait till the performer notices a problem and then they fix it.

Talk Back

Some soundboards have built in microphones right on the mixer. These microphones are typically called ‘talk backs’, are used for communicating to the stage monitors or in ear monitors. The use of these is best for obtaining the best communication between the mixer and the stage. There are however, disadvantages in using talk backs on stage wedge monitors. Monitors give off a lot of sound and if the sound tech were to be speaking to the musicians, there is a large chance that people in the congregation would hear as well. Talk back microphones are best used during practices and sound checks and shouldn’t be used during a service. If running in ear monitors, the sound tech or director can now have a one way conversation with the musician(s) of his choice and no one will be able to hear.

If your soundboard doesn’t have a built in talk back function, the next best way to serve the same purpose would be to connect a microphone through a XRL cable directly into a channel on the board (if there is an availability of channels). From here changing the auxiliaries/monitor channels will help deliver the amount of sound needed for talk back to the stage. Make sure however, that the volume slider is off, so that the sound tech’s voice doesn’t go through the mains. here is a link to a simple video on how directors  can communicate band mates https://youtu.be/cqm565UOm0I (I use this method a lot)

Conclusion

In almost all situations, having the ability to speak to the stage without yelling or getting their attention is through talk backing. Some soundboards will not have this feature, so it is best to connect a spare microphone to a spare channel. Remember that talk back is for the sound engineer to speak to the musicians and not the other way around. Get used to speaking through a microphone to your musicians. Not only will this help improve the quality of the mix but also help limit the amount of time wasted trying to get attention.

How To Mic A Drum Kit For Church

A church can have a very small sanctuary or a very large sanctuary and still require mics on the drum set in order to get the best sound. A lot of sound techs think that a drum set sounds loud enough in a small sanctuary, and this may be true, but does it sound even, equalized, and good? The same rules apply at any small bar or club when it comes to micing your drums in a church. But how many microphones do you need? How far away should they be placed? And what about the volume? All these questions have been asked before by many, so let me try and help you all out!

When it comes to the smaller sanctuaries, a lot of sound engineers will not mic the drum set due to the loudness of the drum set already. This is their first mistake. If the drums are loud, you may want to consider either an electric drum set, or some other muffling concepts, however leaving them un mic'd is not a good idea. The reason for this is drums are located usually in the back of the stage. This means the sound from the kit will only be coming from one direction, causing an uneven sound compared to the rest of the worship team. The team will usually be plugged into the house speakers, resulting in a more uniform sound throughout the church. Placing a select few overhead microphones over the drum set will help mix in the beat with the melody.

Using two overhead microphones is a great way to get the “whole” drum set sound through. These do not need to be the best quality microphones; however, condenser microphones work the best. Place these on mic stands, and place them around 12-18 inches above the tallest cymbal. Make sure you have one over the right side of the drum set as well as one on the left side. If possible, try and pan these two mic's giving the room a more realistic sound. If you are using condenser mics’, make sure you have a fully charged battery in them(or turn phantom power on), and you have them switched on! These overhead mics should pick up the whole drum set respectfully. If you can, throw an extra mic in the bass drum for that extra bass boost.

If this is too over powering, you may want to skip the overhead mics and stick with only two mics: the bass drum mic, and the snare drum mic. A lot of times in the mix, the snare and bass drum will be covered up by the other louder instruments in the band. By having a bass mic as well as a snare mic turned up a little over half, you will find the mix will sound better as a whole. In addition, these two drum voices are usually the ones that carry the beat, so by increasing their volume, the congregation and worship team will be able to follow along a lot easier.

If you can, use an actual bass drum mic for this, or at least a mic that can handle a lot of lows. There are a few ways you can set this mic up. The first and most obvious is to hook it up to microphone stand and place it a few inches away from the bass drum resonance head. Another way to place this mic is by putting it in the actual bass drum itself; however, the only way you can do this is if you have a hole in your resonant drum head. Both work well for sound, and can be equalized to sound great! As for the snare, any mic will do. I would suggest the Shure Sm57, they tend to carry the best tone for the snare drum. Place your microphone on a stand and hover it over the drum 1-3 inches from the head. Depending on the angle of the mic, you should be able to capture some of your other voices on the kit through this mic. Just experiment a little with it.

These are some very basic steps when it comes to setting up the right sound for your drum set in a sanctuary or church. If you have the room on the soundboard, it’s always good to have at least some of your drum set in the mix. It may increase your volume a little, but the even sound it will produce will outweigh the problems you had before!

Acoustic Sound Definitions & terms

Absorption - The process of changing sound energy into heat energy with special materials. This will then lower the amount of sound reflected back.

Active - A type of PA speaker that is self powered; meaning that the speaker has a built in amplifier. Opposite to passive speakers.

Acoustical Environment - The features of a given room, influenced by the absorption, refraction and it's dimensions.

Acoustical Material - A fabric like material designed to absorb sound in reflective environments. (ex. gymnasium walls or church sanctuaries…etc.)

Acoustics - The science of sound and its properties/effects on a given environment.

Anechoic - Sound without any echo.

Amplifier - Audio amps (amplifiers) are the units that convert the finished, mixed signals (from the soundboard) into electrically, powerful signals for powering the loudspeakers.

Artificial reverberation - Sound passed through an acoustic or electric process in a common effect known as reverb. This method is used to make a sound/signal more realistic. Effect units may have default settings to simulate the sound in desired places or surfaces like; rooms, plates, concert halls, bathrooms, stadiums…etc.

Attack - The start/beginning of a sound. On a compressor unit, the attack refers to the speed in which the compressor begins to reduce the signal as it passes through the threshold. You will generally see an 'Attack' knob on compressor and gate units.

Attenuate - The reduction of an electrical or acoustical level.

Audible frequency range - Perceptible range of frequencies heard by the human ear. (20Hz to 20,000Hz)

Auditory system - The sensory system in the ear that gives the sense of hearing.

Background noise - Unnecessary noise from sources not pertaining to the object of significance. Structureborne, airborne and instrument noise are forms of unwanted noise. Background noise can be a cause of sound bleeding from other microphones. To help resolve this, the use of gates will be very helpful.

Bandpass filter - A filter that reduces signals under and above the desired passband.

Bandwidth - The entire frequency range of a system.

Bass - The lowest range of perceptible frequencies starting around 20 Hz.

Boomy - A listening term, that refers to an overload of lower end frequencies.

Bidirectional - Known as a type of pick-up pattern in microphones that will capture sound from the front and back of the diaphragm.

Bright - A listening term, that refers to an excess of higher end frequencies.

Channel balance - In a stereo system, the channel balance refers to the symmetry of sound levels between the left and right speakers. This action, on a sound board, is usually called 'panning'.

Clipping - A type of distortion that can occur when an amplifier is driven into overload. Clipping can happen throughout all the stages of your church PA system; starting from an input on a soundboard, to the final output of the amplifiers/speakers.

Cloud - An acoustical panel suspended from the ceiling to reduce the amount of reflections.

Compression - The process of reducing the dynamic range of a signal. Generally used for vocals, instruments and drums. How to set up compressors.

Crossover frequency - The dividing signal in a speaker of different frequencies

Decibel (dB) - A number represented for the loudness of sound to the human ear.

Digital Delay - Effect which controls the input of a signal and then repeats after a period of time. Delay units have controls for decaying of the echo and reverb.

DI Box - Direct Input Boxes are used to change different impedance levels from instruments to the soundboard.

Dynamic headroom - The ability of a sound device to reach musical peaks.

Echo - A sound that has returned from its original source and was delayed multiple times.

Equalization - The process of altering frequency responses of a device to achieve a desired response.

Equalizer - In a system, the equalizer is designed to change the frequency response of a signal.

Feedback - Unwanted interaction between the speakers and microphones of a PA system.

Frequency - The calculation of fast variations of a periodic signal, expressed in cycles per second (Hz).

Frequency Response - Changes in the sensitivity of a circuit or room with regards to frequencies.

Front of House - The area that the audience (or congregation) has access to. Mainly excluding the stage and behind stage. Normally where everyone sits or stands at a service or show.

Fundamental - The lowest frequency of a note.

Fusion Zone - When all sounds (natural, eclectically generated or reflected) are fused together and heard by an observer’s ears; this will result in the apparent increase in sound level. Also called, the Hass Effect.

Gain - An increase in level. On most soundboards, this is a function knob that enables the input level into a channel.

Hard room - An environment which the surfaces have a very low value of sound absorption and are reflective. Opposite from a soft room.

Headphones - A tool (device) for the ability to hear any specific instruments/channels.

Headroom - The capability of an amp to go past its rated power for short durations without distortion.

Hertz (Hz) - The unit of frequency that means the same as cycles per second. (Abbreviated as Hz)

Impedance - The resistance to the flow of electric energy measured in ohms.

KHz - Kilohertz - 1,000Hz.

Live end dead end - A treatment plan for acoustics that at one end of the environment it is reflective and the other end is very absorbent.

Loudspeaker - An electroacoustical transducer that alters electrical energy into acoustic (audible) energy.

Masking - Adding a presence of sound to one source by another.

Microphone - A device that converts sound waves (acoustical energy) into electrical signals.

Midrange - In a speaker, the midrange is created with a tweeter for high frequencies and a sub-woofer for the low end frequencies.

Monitor (Wedge) - A speaker or in-ear monitor system, used on a stage to send sound to the musicians.

Muting - A dramatic reduction in the volume level. On a soundboard this function is called the ‘mute’ button.

Noise - Interference of either an electrical or acoustical signal. Gates are ideal for greatly reducing acoustical noise on stage.

Octave - In interval multiples of two between the frequencies bands 20Hz-40Hz. Each octave you add on the lower end requires that your speakers move four times as much air.

Omnidirectional - Referred to as a type of pick-up pattern in microphones. Omni, meaning ‘all around’; captures sound from all directions (360°).

Patch Cable - Typically an unbalanced quarter inch (1/4) phone jack used to connect instruments and other devices. Not suggested to be used for powering monitors or speakers.

PA system - Public address system; its purpose to amplify any given source used for communication in public areas.

Passive - A type of PA speaker that is unpowered, so that the speaker needs an external amplifier source, like a powered mixer or a power amplifier, in order to operate. Opposite to active speakers.

Phantom Power (+48V) - A function on most soundboards used to send 48 votts of electrical currents through audio cables. Mostly all condenser microphones require phantom power to work.

Phon - Unit of the audible loudness level of a tone.

Pick-up Pattern - For every microphone there is a property know as directionality. Directionality is described as the microphone’s sensitivity to sound from numerous directions.

Pitch - The perspective frequency of tones.

Psychoacoustics - The science of sound and its interaction on the auditory system.

PowerCon - Used for connecting the amplifiers and speakers in a PA system. The end of the cable has a twist lock feature, to ensure the connectivity of the cable. Has a very similar design to the speakon cable.

PZM Microphone - A special type of condenser microphone that has a plate (flat surface) that vibrates to all sound locations near it. Also called a Pressure Zone or Boundary microphone.

Refraction - Sound that is redirected by a process of bending sound waves through material with different sound velocities.

Returns - A process used with effect units. A signal must be sent to an effect unit and then 'returned' back to the soundboard.

Reverberation - The persistence of sound when enclosed in a space, which has reflective properties, after the source of the sound, has stopped.

Reverberation time - The falling off of a sound in a closed environment because of reflections.

Slap back - A distinct reflection from a nearby surface.

Snakes - Audio snakes are used for carry many signals in a single cable, great for long distances.

Soft room - An environment with highly absorbent surfaces. Opposite from a hard room.

Sone - The unit of measurement used for the subjective loudness on the auditory system.

Sound insulation - The ability of a given environment’s, physical composition, to stop sound from leaving the wanted origin. Different types of insulation have numerous effects on the sound. This sound energy is not necessarily absorbed; however the sound maybe reflected back or the impedance may become mismatched.

Sound isolation - The degree of acoustical separation between two environments. Like a control room to the live recording room. Some headphones are also sound isolating.

(SPL) Sound pressure level - Expressed in decibels as the loudness or volume of a level.

Sound spectrograph - A device used to measure the level, frequency and time of a signal.

Sound waves - Frequency determines the length of waves and the amplitude (loudness) determines the height of the waves. 

Speakon cable - Used to connect amplifiers to speakers, generally used in pro audio systems. This connector has a twist lock feature, to ensure the connectivity of the cable. (Similar to the PowerCon connector)

Spectral balance - The balance across the whole frequency spectrum of the system.

Splaying - A physical attribute to an environment where the walls are purposefully constructed off square. This is done to imperfect the flow of returning sound waves. Another method used for reducing echoes.

Stereo - Artificial simulation of natural human hearing by creating a 3-D image through a system of supplying two different sources with slightly singular mixes and sounds. In the case pertaining to a PA system, this would be called the Left and Right channels. For true stereo to be achieved; the soundboard, processing amplifiers and two separate speakers must be available.

Subwoofer - A speaker cabinet created for low-frequency reproduction. The best ability that a subwoofer should reach is into the bottom octave (20-40Hz).

Tangential mode - A physical room atmospheric mode produced by reflections from four of the six surfaces.

Threshold of feeling - Sound pressure that can cause discomfort and pain. Situated around 120 dB above the threshold of hearing.

Threshold of hearing - The lowest sound level that can be heard by the auditory system. (around 20uPA)

Timbre - The superiority of a sound that can be notable from other sounds of similar pitch and level.

Tip-Ring-Sleeve (TRS) - Audio cable ends, generally used for connecting instruments through to the soundboard. Called TRS for its physical features. Tip is the left channel signal the Ring is the right channel signal and the Sleeve is normally the ground.

Tone - Is the result of an auditory sensation of the given pitch.

Treble - The highest of all frequencies in the audio spectrum.

Unidirectional - Referred to as the type of pick-up pattern in microphones that will only capture sound from one direction.

Watt - A unit of electricity and acoustical power. The energy is expressed in intervals of seconds.

White noise (ANS) - An audible noise with a constant frequency spectrum. This is used to calculate and equalize the response of a system.

Setting Up Monitors At Church

Being in a worship team for over 9 years now, I have really come to realize how important it is to have your own monitor. As a worship team, it is very important to be able to hear each other, as well as yourself. A drummer will not have this problem as much as the others; however it is still important for him/her to be able to hear others. As a drummer, it is very hard to play on time and with the right dynamics if you cannot hear the other members. For the melodic musicians, it is super important to be able to hear the specific key the song is in, as well as the notes they are playing. For the singers, it is crucial that they hear the band so they can sing in the correct key and tone. So with this being such an important issue, how do you set up these monitors to get the best results?

Who Gets A Monitor?

First things first, check how many working monitors you have in your church. The ideal set up would be giving each member of the worship team their own monitor. However, this can be very cost consuming, so there are ways around it. For example, if you have more than one singer, they can usually share a monitor, same goes for the rhythm section. If you have a conga player along with a drummer, they can usually get away with sharing one monitor. You can often get by with the bass player and dummer sharing a monitor. The most important musicians in the worship team are the leader(s), and the rhythm player(s). These are usually the ones who drive the music, so if they are having troubles hearing the whole feeling and sound may be 

Settings and Distances Between Monitors

With years of experience in this field, I have come to realize the importance of where you actually set these monitors up. The distance and angle can really change the sound on the stage, as well as the sound in the congregation (house). Ideally, you want to set them up so you can hear them clearly. For the drummer, you will want to set his/her monitor up to the left or right of them. Angle it so it is facing them, allowing a clear path for the sound to travel (try not to let music stands get in the way). The lead guitarists, singers, and other musicians that are standing, should have similar set ups. Make sure they are angled upwards to direct the sound towards their ears. All in all, the monitors should be around 2-4 feet away from the musician, no more. This will cause the musician to not be able to hear, resulting in a volume increase on the monitor. This could result in a muddy sounding stage. If you are experiencing this, gates often can help.

Make sure you spread the monitors out evenly. Clumping them together will mix the sounds up. Keep at least 5-10 feet between each monitor. If you have a smaller sanctuary, you may want to consider lowering the overall volume, or reducing the amount of monitors you use. You want to make sure you do not face the monitors any more than 45 degrees towards the congregation. This will result in an uneven mix in the house. The sound techs are equalizing 2 things, the stage sound for the musicians, and the house sound for the congregation. Having a monitor at an angle that faces the congregation will mess with the sound in the house. So make sure you have the monitors facing the stage only! If you are running an in-ear-monitor system, you gladly do not have too much to worry about on this matter.

Another key thing to remember when setting up monitors is the distance from the walls. Sound waves bounce off of walls and change direction. If you have a monitor that is directly facing the wall, you may want to turn it away. Hanging acoustic material can be used to absorb these reflections. This will avoid any unnecessary sounds bouncing the wrong way! Also, remember to hide those cords! Nothing is worse than a messy stage, so when you can, hide any cords you have.

The Monitor Mix

The mix is very personal to every musician. Remember that the whole point of monitors is to allow each musician to hear them selves first and the rest of the team second! Make sure you have an even sound in all the monitors first, capturing the whole team on an even note. This way you have a balance throughout the whole stage. Then, increase each member’s volume accordingly. Each person is different, so you may find some variety in the way each on sets up his/her monitor. Just make sure you do not over power everything. To high a volume on the monitors will not only sound bad on the stage, but it will encourage faster and louder playing for the whole team. Also, the sound in the congregation will be affected as well.

When every monitor is set up correctly, and mixed properly, the worship team will sound better, encouraging more energy and soul in the music. You will be surprised how much better a team will sound if they can hear each other well. The key to all of this is communication. Make sure you are communicating with the team throughout the sound check, asking what each individual wants.

In Ear Monitors (IEM)– Advantages and Disadvantages

In ear monitors have become increasingly popular in any venue with regular music performances. In the church market alone in ear monitors are changing the way that sound engineering works. The reduced stage volume makes it much easier for sound engineers to get a clean mix. Now, be careful, there are also many disadvantages to in-ear-monitors. The price alone can often scare people away. Let’s take a look at the pros and cons of using personal in ear monitors.

How In Ear Monitors Work

In ear monitors are quite simple. You simply plug in a patch cable on your monitor/auxiliary output on your mixer and plug it into the back of your in ear monitor transmitter. The transmitter will then take the signal and assign it a frequency and send it to the corresponding receiver. The receiver is simply a belt pack, which receives the signal and lets you plug in any type of headphone that you choose.

Advantages of In Ear Monitors

Reduced Stage Noise Of In Ear Monitors.

The most obvious advantage of in ear monitors is the reduced stage sound. Sound engineers are able to do a better job of mixing because there is much less noise pollution. Not only will in ear monitors make it easier for the sound engineer to avoid feedback, but it will also help reduce the noise pollution from the stage, may times the audience in the first few rows can hear the monitors louder than the mains.

Portability Of In Ear Monitors

This one is fairly straight forward, with wedge monitors you need a truck, or sometimes even a trailer if you plan on moving the monitors from venue to venue. With in ear monitors all of your receivers/transmitters can easily fit into a rack mount kit, and is very portable. When you get to the venue, simply pass out the receivers/headphones to the musicians and plug your receivers directly into the mixer - Done.

Personal Control With In Ear Monitors

This is another major advantage of using in ear monitors. Even if you are on the same monitor mix as someone else in your band, you can still control the volume of your channel on your belt pack/receiver. Also depending on the brand that makes your in ear monitors, some companies actually make monitor systems that allow you to mix your own in ear monitor mix, allowing you to have total control of what you listen to.



Disadvantages of In Ear Monitors

The Cost Of In Ear Monitors

This used to be a much larger problem than it is now, but price is still an important factor in your decision. For a good setup of in ear monitors you are looking at paying somewhere between $300-$1000 online for each set of in ear monitors that you want to purchase. Also, if you want a rack mount kit for your transmitters then you are looking at another $50 per set, plus the cost of the actual rack ($100-300, depending on the size) Right now is a very good time to start looking at your budget for sound gear at your church.

Frequencies Of In Ear Monitors

This is a fairly large problem, and should be carefully measured before purchasing your own set of in ear monitors. A lot of times performers notice a couple problems…

The performers signal is fuzzy – You can usually fix this problem by replacing the battery on the receiver, or moving the transmitters away from other electronic devices, they can sometimes get interference if they are stacked right beside a lot of power amps, or other rack mounted effects. The distance between the transmitters and the receivers is also important. Make sure you read and know the maximum distance that your IEM system can perform in.

The performer is getting interference from other monitor channels – This can usually be fixed by simply changing the frequency of all the transmitters and receivers.

The performer can hear some sort of tv/radio station (or in extreme cases, baby monitors) in the background – Wireless monitors transmit on the same band of frequencies that old television stations used to use, sometimes you may still pick up the odd FM station or just random radio interference. There have been several times when I have mixed, when the worship band hears a sound of a baby in their in ear monitor. Know that there are allot of signal movements between the sound board, wireless transmission and then the receiver pack; to make for some interference. All you can do in this matter, is change your frequencies on the receiver and the transmitter.

The Lack of Ambient Sounds

Many in ear monitors also come with sound isolating headphones which create a bit of a problem for many lead vocalists. Many vocalists get their energy from hearing the crowed singing along/ screaming/ cheering. When you have sound isolating headphones you don’t hear anything other than what is coming through your monitor mix. Many lead vocalists have gone to wedge style monitors because of this problem. Or they insist on only using one headphone instead of two.

Conclusion

In ear monitors are great for churches/ venues/ bands that have larger budgets. They can definitely make a difference in your performance, and in your overall sound, but I wouldn't recommend buying lower quality or entry level personal wireless monitor systems. They often offer less quality, and can be more distracting than they are helpful. If you can afford some middle-higher level wireless systems then I defiantly think that you will be happy with your purchase, even if you just get a set for your drummer and/or lead vocalist it will make a huge difference in the performance value of your show or church service.

SIGNAL FLOW

SIGNAL FLOW

Input transducers

 

Audio engineers use a range of microphones for different live sound applications.

 

Cardioid mics are widely used in live sound, because their "apple-shaped" pickup pattern rejects sounds from the sides and rear of the mic, making it more resistant to unwanted feedback "howls".

Many types of input transducers can be found in a sound reinforcement system, with microphones being the most commonly used input device. Microphones can be classified according to their method of transduction, polar pattern or their functional application. Most microphones used in sound reinforcement are either dynamic or condenser microphones. One type of directional microphone, called cardioid mics, are widely used in live sound, because they reduce pickup from the side and rear, helping to avoid unwanted feedback from the stage monitor system.

Microphones used for sound reinforcement are positioned and mounted in many ways, including base-weighted upright stands, podium mounts, tie-clips, instrument mounts, and headset mounts. Microphones on stands are also placed in front of instrument amplifiers to pick up the sound. Headset mounted and tie-clip mounted microphones are often used with wireless transmission to allow performers or speakers to move freely. 

Other types of input transducers include magnetic pickups used in electric guitars and electric basses, contact microphones used on stringed instruments, and pianos and phonograph pickups (cartridges) used in record players. Electronic instruments such as synthesizers can have their output signal routed directly to the mixing console. A DI unit may be necessary to adapt some of these sources to the inputs of the console.

Wireless

Wireless systems are typically used for electric guitar, bass, handheld microphones and in-ear monitor systems. This lets performers move about the stage during the show or even go out into the audience without the worry of tripping over or disconnecting cables.

Mixing consoles

 

Mixing consoles are the heart of a sound reinforcement system. This is where the sound engineer can adjust the volume and tone of each input, whether it is a vocalist's microphone or the signal from an electric bass, and mix, equalize and add effects to these sound sources. Doing the mixing for a live show requires a mix of technical and artistic skills. A sound engineer needs to have an expert knowledge of speaker and amplifier set-up, effects units and other technologies and a good "ear" for what the music should sound like in order to create a good mix.

Multiple consoles can be used for different purposes in a single sound reinforcement system. The front of house (FOH) mixing console is typically located where the operator can see the action on stage and hear what the audience hears. For broadcast and recording applications, the mixing console may be placed within an enclosed booth or outside in an OB van. Large music productions often use a separate stage monitor mixing console which is dedicated to creating mixes for the performers' on-stage. These consoles are typically placed at the side of the stage so that the operator can communicate with the performers on stage. 

Signal processors

Small PA systems for venues such as bars and clubs are now available with features that were formerly only available on professional-level equipment, such as digital reverb effects, graphic equalizers, and, in some models, feedback prevention circuits which electronically sense and prevent audio feedback it becomes a problem. Digital effects units may offer multiple pre-set and variable reverb, echo and related effects. Digital loudspeaker management systems offer sound engineers digital delay (to ensure speakers are in sync with each other), limiting, crossover functions, EQ filters, compression and other functions in a single rack-mountable unit. In previous decades, sound engineers typically had to transport a substantial number of rack-mounted analog effects unit devices to accomplish these tasks.

Equalizers

 

Graphic equalizer

Equalizers are electronic devices that allow audio engineers to control the tone and frequencies of the sound in a channel, group (e.g., all the mics on a drum kit) or an entire stage's mix. The bass and treble controls on a home stereo are a simple type of equalizer. Equalizers exist in professional sound reinforcement systems in three forms: shelving equalizers (typically for a whole range of bass and treble frequencies), graphic equalizers and parametric equalizers. Graphic equalizers have faders (vertical slide controls) which together resemble a frequency response curve plotted on a graph. The faders can be used to boost or cut specific frequency bands.

Using equalizers on frequencies that are too weak such as a singer with modest projection in their lower register can be boosted. Frequencies which are too loud, such as a "boomy" sounding bass drum, or an overly resonant dreadnought guitar can be cut. Sound reinforcement systems typically use graphic equalizers with one-third octave frequency centers. These are typically used to equalize output signals going to the main loudspeaker system or the monitor speakers on stage. Parametric equalizers are often built into each channel in mixing consoles, typically for the mid-range frequencies. They are also available as separate rack-mount units which can be connected to a mixing board. Parametric equalizers typically use knobs and sometimes buttons. The audio engineer can select which frequency band to cut or boost, and then use additional knobs to adjust how much to cut or boost this frequency range. Parametric equalizers first became popular in the 1970s and have remained the program equalizer of choice for many engineers since then.

A high-pass (low-cut) and/or low-pass (high-cut) filter may also be included on equalizers or audio consoles. High-pass and low-pass filters restrict a given channel's bandwidth extremes. Cutting very low frequency sound signals (termed infrasonic, or subsonic) reduces the waste of amplifier power which does not produce audible sound and which moreover can be hard on the low-range speakers. A low-pass filter to cut ultrasonic energy is useful to prevent interference from radio frequencies, lighting control, or digital circuitry creeping into the power amplifiers. Such filters are often paired with graphic and parametric equalizers to give the audio engineer full control of the frequency range. High-pass filters and low-pass filters used together function as a band-pass filter, eliminating undesirable frequencies both above and below the auditory spectrum. A band-stop filter, does the opposite. It allows all frequencies to pass except for one band in the middle. A feedback suppressor, using a microprocessor, automatically detects the onset of feedback and applies a narrow band-stop filter (a notch filter) at specific frequency or frequencies pertaining to the feedback.

Compressors

A rack of electronic audio compressors

Dynamic range compression is designed to help the audio engineer to manage the dynamic range of audio signals. Prior to the invention of automatic compressors, audio engineers accomplished the same goal by "riding the faders", listening carefully to the mix and lowering the faders of any singer or instrument which was getting too loud. A compressor accomplishes this by reducing the gain of a signal that is above a defined level (the threshold) by a defined amount determined by the ratio setting. Most compressors available are designed to allow the operator to select a ratio within a range typically between 1:1 and 20:1, with some allowing settings of up to ∞:1. A compressor with high compression ratio is typically referred to as a limiter. The speed that the compressor adjusts the gain of the signal (attack and release) is typically adjustable as is the final output or make-up gain of the device.

Compressor applications vary widely. Some applications use limiters for component protection and gain structure control. Artistic signal manipulation using a compressor is a subjective technique widely utilized by mix engineers to improve clarity or to creatively alter the signal in relation to the program material. An example of artistic compression is the typical heavy compression used on the various components of a modern rock drum kit. The drums are processed to be perceived as sounding more punchy and full.

 

Noise gates

A noise gate mutes signals below a set threshold level. A noise gate's function is in, a sense, opposite to that of a compressor. Noise gates are useful for microphones which will pick up noise that is not relevant to the program, such as the hum of a miked electric guitar amplifier or the rustling of papers on a minister's lectern. Noise gates are also used to process the microphones placed near the drums of a drum kit in many hard rock and metal bands. Without a noise gate, the microphone for a specific instrument such as the floor tom will also pick up signals from nearby drums or cymbals. With a noise gate, the threshold of sensitivity for each microphone on the drum kit can be set so that only the direct strike and subsequent decay of the drum will be heard, not the nearby sounds.

Effects

Reverberation and delay effects are widely used in sound reinforcement systems to enhance the sound of the mix and create a desired artistic effect. Reverb and delay add a sense of spaciousness to the sound, imitating the sound of a singing voice or instrument in a large, reverberant hall. Many mixing boards designed for live sound include on-board reverb effects. Modulation effects such as Flanger, phaser, and chorus are also applied to some instruments. An exciter, such as a "Harmony" or "Octave" effect, "livens up" the sound of audio signals by applying dynamic equalization, phase manipulation and adding artificially synthesized harmonic frequencies.

The appropriate type, variation, and level of effects are quite subjective and are often collectively determined by a production's audio engineer, artists, bandleader, music producer, or musical director. Reverb, for example, can give the effect of signal being present in anything from a small room to a massive hall, or even in a space that does not exist in the physical world. The use of reverb often goes unnoticed by the audience, as it often sounds more natural than if the signal was left "dry" (without effects).  The use of effects in the reproduction of 2010-era pop music is often in an attempt to mimic the sound of the studio version of the artist's music in a live concert setting. For example, an audio engineer may use an Auto Tune effect to produce unusual vocal sound effects that a singer used on their recordings.

Feedback suppressor

A feedback suppressor detects unwanted audio feedback and suppresses it, typically by automatically inserting a notch filter into the signal path of the system, which prevents feedback "howls" from occurring. Audio feedback can create unwanted loud, screaming noises which are disruptive to the performance, and which can damage performers' and audience members' ears and speakers. Audio feedback from microphones occurs when a microphone "hears" the sound it is picking up through the monitor speakers or the main speakers. While microphone audio feedback is almost universally regarded as a negative phenomenon, in hard rock and heavy metal music, electric guitarists purposely create guitar feedback to create unique, sustained sounds with their guitar and guitar amplifier. This type of feedback is sought out by guitarists, so the sound engineer does not try to prevent it.

Power amplifiers

 

A power amplifier is an electronic device which uses electrical power and circuitry to boost a low-voltage level signal (e.g., the signal from a vocalist's mic) and provides enough electrical power to drive a loudspeaker and produce sound. All speakers, including headphones, require power amplification. Most professional audio amplifiers also provide protection from clipped (overloaded) signals, as a power amplifier pushed into clipping can damage or destroy speakers. Amplifiers also typically provide protection against short circuits across the output, and excessive temperature (e.g., overheating). A limiter is often used to protect loudspeakers and amplifiers from power amp clipping.

Audio engineers select amplifiers that provide enough headroom. "Headroom" refers to the amount by which the signal-handling capabilities of an audio system exceed a designated nominal level.  Headroom can be thought of as a safety zone allowing transient audio peaks to exceed the nominal level without damaging the system or the audio signal, e.g., via clipping. Standards bodies differ in their recommendations for nominal level and headroom. When an audio engineer has selected an amplifier (or amplifiers) with enough headroom, this also helps to ensure that the signal will remain clean and undistorted.

Like most sound reinforcement equipment products, professional amplifiers are typically designed to be mounted within standard 19-inch racks. Rack-mounted amps are typically housed in road cases, sturdy plastic protective boxes which prevent damage to the equipment during transportation. Active loudspeakers have internally mounted amplifiers that have been selected by the manufacturer to be a good amplifier for use with the given loudspeaker. Some active loudspeakers also have equalization, crossover and mixing circuitry built in.

Since amplifiers can generate a significant amount of heat, thermal dissipation is an important factor for operators to consider when mounting amplifiers into equipment racks. Many power amplifiers feature internal fans to draw air across their heat sinks. The heat sinks can become clogged with dust, which can adversely affect the cooling capabilities of the amplifier.

In the 1970s and 1980s, most PAs employed heavy Class AB amplifiers. In the late 1990s, power amplifiers in PA applications became lighter, smaller, more powerful, and more efficient, with the increasing use of switching power supplies and Class D amplifiers, which offered significant weight- and space-savings as well as increased efficiency. Often installed in railroad stations, stadia, and airports, Class D amplifiers can run with minimal additional cooling and with higher rack densities, compared to older amplifiers.

Digital loudspeaker management systems (DLMS) that combine digital crossover functions, compression, limiting, and other features in a single unit have become popular since their introduction.  They are used to process the mix from the mixing console and route it to the various amplifiers. Systems may include several loudspeakers, each with its own output optimized for a specific range of frequencies (i.e. bass, midrange, and treble). Bi-amplification, tri-amplification, or quad-amplification of a sound reinforcement system with the aid of a DLMS results in a more efficient use of amplifier power by sending each amplifier only the frequencies appropriate for its respective loudspeaker. Most DLMS units that are designed for use by non-professionals have calibration and testing functions such as a pink noise generator coupled with a real-time analyzer to allow automated room equalization.

Main loudspeakers

 

A simple and inexpensive PA loudspeaker may have a single full-range loudspeaker driver, housed in a suitable enclosure. More elaborate, professional-caliber sound reinforcement loudspeakers may incorporate separate drivers to produce low, middle, and high frequency sounds. A crossover network routes the different frequencies to the appropriate drivers. In the 1960s, horn loaded theater loudspeakers and PA speakers were almost always "columns" of multiple drivers mounted in a vertical line within a tall enclosure. The 1970s to early 1980s was a period of innovation in loudspeaker design with many sound reinforcement companies designing their own speakers. The basic designs were based on commonly known designs and the speaker components were commercial speakers.

The areas of innovation were in cabinet design, durability, ease of packing and transport, and ease of setup. This period also saw the introduction of the hanging or "flying" of main loudspeakers at large concerts. During the 1980s the large speaker manufacturers started producing standard products using the innovations of the 1970s. These were mostly smaller two way systems with 12", 15" or double 15" woofers and a high frequency driver attached to a high frequency horn. The 1980s also saw the start of loudspeaker companies focused on the sound reinforcement market. The 1990s saw the introduction of Line arrays, where long vertical arrays of loudspeakers with a smaller cabinet are used to increase efficiency and provide even dispersion and frequency response. This period also saw the introduction of inexpensive molded plastic speaker enclosures mounted on tripod stands. Many feature built-in power amplifiers which made them practical for non-professionals to set up and operate successfully. The sound quality available from these simple 'powered speakers' varies widely depending on the implementation.

How Do Power Amplifiers Work

Amps or amplifiers are one of the four main components to a church audio system or any live sound production. The purpose of amplifiers is to take the weak, powerless signals, generated from the soundboard, process them and then add electrical signals to power the speakers. Proper care will ensure the best working amps; with minimal signal loss and quality signals sent to the mains.

WHERE SHOULD AMPLIFIERS BE PLACED?

The amplifier is generally the final step before the signal gets converted to into sound. It is important that these amplifiers be placed in a dry, cool environment. The amplifiers should never be touched, unplugged or altered in any way if you are unqualified, or untrained to do so. For security, and safety, I recommend securing your amps in some sort of rack mount solution where the cables are organized well, and out of the way. 

Most churches have their system set up and calibrated with the appropriate amp levels, so generally you shouldn’t have to change anything on them once your system is installed. Air flow is important as well, as some churches situate their amps in a closet, with poor or no ventilation. This is bad for a few reasons. Firstly, it is a fire hazard if a stack of amps are operating on top of one another without any air flow. Secondly, the initial processing of the amps are normally equipped with over heating sensors that when over heated, will shut down. Be careful of this because older amplifiers may not have this function. Make sure after all the services or when the amps aren’t in use, that you turn them off.

HOW SHOULD THEY BE HOOKED UP?

Like everything else in audio, it is important that you don’t lose signal quality. Generally speaking you want to keep your amps as close to the speakers as you can. A common problem with audio occurs when the power amplifiers are too far away from the speakers, venues will lose a lot of sound quality with longer cables. The shorter your cables, the better your sound will be. There are two types of cables that are commonly used to transfer the powered signal from your amp to your speakers; speakon cables, and quarter inch cables. Either cable will work fine, but you want to make sure that the cable is shielded and that it is rated for the same wattage/voltage as the amount of power you are sending through it. Do not under any circumstance use unshielded instruments to connect your power amp to your speakers, you will damage your amp, the cable, and the speaker. Below is a little table to guide you in your calculations and choice of cable.

Words Of Caution

Make sure that you carefully examine the power rating of your amplifier and your speakers. If you amp is either over or underpowered it will result in damage to the amp, and to the speaker. Make sure that you consult an audio specialist when making your final purchase, we will trash that more when we dive into ohms and watts calculations.

Cost

Audio amplifiers can have a wide range of prices; usually starting from around $350-$900 and upwards. It is important that you have great quality amplifiers for your church; you do not want unreliable amps powering expensive speakers.

Conclusion

Amplifiers are defiantly important because of their responsibility in the reproduction of your audio signals. Make sure that your amplifiers are properly taken care of and placed in an appropriate location. This will ensure the quality of sound and the life of your amps with regards to your whole PA system.

Stay sound.