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Technology in church |
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A work in progress, by Alex Wegman Partial revision May 2006 Why? What? Where? How?
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Note: As I revise and amend this article, I reflect on the thrust of it possibly aiming at a more modernistic church setting. This concerns me, but hopefully the underlying ideas and wisdom will be of use to people, wherever they are on the communal journey of faith. Church services are hi-tech. Complex sound, lighting and video material that was once just the realm of the rock and roll and corporate functions has become very prominent in the Sunday service. Attendees at many large church meetings and events are treated to a full audio-visual package, that blurs the lines between entertainment and reverence, consumption and worship. For churches that have an extensive audio-visual installation already in place, this article is not aimed primarily at you. The main objective here is to provide encouragement for church groups who are exploring new technologies for the first time. It is hoped that the thought process that goes into implementing new technologies will be assisted by some of the ideas shared here. I will attempt to keep electronic and acoustic `tech-speak’ to a minimum, but will also endeavour to explain technical concepts that are important in understanding the subject matter. Some of the brands of gear mentioned may not be among the cheapest, but I have mentioned them simply as possible examples of good quality equipment (I’m not officially endorsing any particular brands !).
The `If Only’ syndrome applies to many of our longings about how we’d like church to be. If Only we had a good minister. If Only we had better (`the right’) music. If Only there was more love in the church. The church’s acquisition of audio-visual equipment often seems to fit this mentality. We know what it’s like to go to some whizz-bang worship service with all the trimmings, only to come away thinking: “If only we had a video screen - think about how many people we’d attract”, or “If only we had that new music, it seems to promote much better worship than what we have at the moment”. Of course, there’re always the issues of church finances, traditionalists, practicalities, apparent lack of skills etc. In the end, it seems that everyone is discouraged, except the church treasurer (who’s gloomy anyway), the traditionalist, the practical pessimist (Mr Hanrahan) and the one with apparently no skills.
I have a certain involvement in the field of audio technology and, while not being the supreme guru of all things electronic, am well aware of much of the gear that is available. I actually like a church meeting to be as low-tech as possible, insofar as `high-tech’ meaning a large, professional sound system; worship band playing all the latest from Sydney and Britain; video screens crossing between words and musician close-ups; lights galore (with the obligatory moving-head luminaires and artificial haze). Some of the best services I’ve been to have had little vocal amplification and no projector of any sort. Something of a golden rule I like to apply to church audio-visual gear is this: Keep it as simple as possible. Make it the best quality possible.
Something to aim for is a sound system that the congregation wouldn't notice, unless it wasn't there. This objective requires skill on the part of the installer and operator, as well as good quality equipment. People shouldn't go to church to hear the sound system.
Fact of life about church sound: A quote on a good quality system will always be more than your church council is prepared to spend. Now no-one likes to spend money. Sound gear in church is usually treated as `an expensive luxury that we can’t afford, so let’s get something cheap’. I’m not attempting to make churches feel bad for not being able to afford `expensive' gear, but I do wish to emphasise the importance of a well-thought out church sound system, whether simple or complex. A particular frustration for the person proposing the installation involves the somewhat intangible attribute of quality – i.e. "Why we should buy this one from a reputable brand even though it is four times the price of the clone from Brand X".
Assuming your church is adequately lit, ventilated and heated, here are some notes on what might be seen as `basic conventions’ in church audio-visual equipment. My views and experience are somewhat tempered by my background in the Anglican Church, with its somewhat traditional physical layout. I am taking into the account the possibilities and potential of the creative stream that is generally and ambiguously termed `alternative worship’. Of course, on top of all this is the reality that church as we know it is undergoing revolution and the application of technology needs much consideration in the big scheme of things (a personal subject of interest to be discussed at another point in time). Some of my ideas present a certain bias, but only with the view of helping avoid particular traps and mediocre results. A non-partial `how-to’ guide is of limited practical use if it contains no aspect of personal experience. This article has been written in Australia and some details regarding standards, regulations and prices would obviously need to be checked in your own location. By the way: I have used terms and descriptions in a way hopefully to be non-confusing. Special care has been taken in the use of terminology. For example: In the real world loudspeakers might be referred to as speakers, or boxes, or wedges or cabinets, or powered boxes etc. Confusion: a speaker is also a term for someone speaking. To keep this clear, I've attempted to consistently use the term loudspeaker, tempting as it may be to shorten it.
1) Sound reinforcement
Some sort of lectern microphone and loudspeaker apparatus is a common fixture in most church buildings. The loudspeakers are often a cruddy column-type design with peeling woodgrain and a similar sound quality to a telephone. It is very important that the congregation be able to clearly hear what is being said by the person speaking from the lectern or wherever the address is coming from. If the church building is sufficiently small then you may get away with no microphones and loudspeakers at all, which is fantastic. This is not always the case, and there is often a desire to record the sermon, provide a hearing-aid loop, etc., so a microphone is needed. In essence, the idea of vocal reinforcement is to reduce the acoustic distance between the speaker and the listener. You can hear someone talking when they are a couple of metres away. Vocal reinforcement is an attempt to simulate this.
Note: The presence of a microphone at the lectern doesn’t negate the requirement for the person speaking to project their voice.
Whether you are investing in a simple microphone-loudspeaker set-up for the first time, or replacing what you have, don’t proceed simply with whatever package-deal the guy at Joe’s Discount Church Public Address Systems thinks is a good idea. Musical instrument stores often have a reasonable range of suitable sound equipment, but ensure you talk to some specialist sound system dealers as well. A good system will be nice to listen to and will not cause listener fatigue. Arrange to test a system out in your building, with a congregation, before committing to it. People know when they hear good sound, and there really is no substitute for a good trial. I am reasonably sure that some sound equipment salespeople use churches as ways of getting rid of the cheap nasty stuff that no-one else wants. Be a smart shopper and surprise them. It’s okay to buy cheap. Just don’t make low cost the primary reason for purchase. If you buy cheap and then need to replace it soon later, it’s harder to convince the parish treasurer a second time than if you spend a little more to start with and get something that works well and lasts. Sound operator morale does tend to suffer when faced with very mediocre equipment that is a pain to use, has limited versatility and sounds awful.
A simple vocal reinforcement system will comprise at least one microphone, an amplifier and a loudspeaker. In reality such installations generally utilise a small mixer, which allows convenient adjustment of volume levels of several separate microphones that are feeding into the same amplifier/loudspeaker.
Microphones
Let’s start at the microphone end. Microphones vary enormously in type, design, intended use, quality and price. As with most things, you certainly get what you pay for - as long as you choose the correct mic for the application. We have all heard feedback - the unpleasant squealing sound which howls through the loudspeakers and makes the sound system operator the object of dark looks. Feedback occurs when the sound from the loudspeakers finds its way back into the microphone, gets amplified and comes out the loudspeakers again. The frequency at which this feedback occurs depends on several factors such as room design, room contents, wall material, microphone/loudspeaker proximity and orientation, sound system set-up and the acoustic behaviour of the components. A good microphone for a lectern application will have a good off-axis rejection, which means that any sound that doesn’t come from directly in front of the microphone is not picked up very well. Cardioid and Super-cardioid microphones have good off-axis rejection (but you need to talk right into them). This characteristic is very useful here because the mic will pick up the person’s voice very well but will not be too sensitive to other noise such as loudspeaker sound which generally comes from another direction. This helps to reduce the chance of feedback. Good microphone designs for the lectern are of the slim, gooseneck type, with a cardioid pattern (e.g. Shure MX412). Dynamic microphones contain a small magnet and coil and require no batteries or external power to operate. Condenser microphones use a capacitor and other electronic components. They require external power to operate, which may be in the form of a small battery or with phantom power which is a means of supplying power via the microphone cable - usually from the mixer. Note for clarification: Condenser and Dynamic are two fundamental types of microphone. The pattern (e.g. cardioid, omni-directional etc.) refers to the pick-up characteristics of the mic and is a separate issue to whether the mic is a dynamic or condenser. In practice, omni-directional microphones are often of the condenser variety - condenser mics lend themselves to certain pick-up patterns better than dynamics. Condenser microphones are a good choice for lectern microphones as they are well suited to the vocal range of frequencies, with a sensitive `upper-end’. They are usually a bit more expensive than dynamic microphones, which are generally not quite as sensitive but good when the sound source is very loud and close (such as shouting straight into it). There is something slightly esoteric surrounding the subject of condenser microphones, and some people have large collections, with a different one for each application. If you look on the internet you often find all kinds of weird and wonderful microphone-related stuff. That is a tangent I won't pursue here... If the microphone is to be a dedicated lectern mic (i.e. not used for other things as well), then it is a good idea to mount it to the lectern. Some sort of shock mount is worthwhile as it prevents mechanical noise - such as someone inadvertently tapping the lectern - from being transferred to the microphone. Sometimes two microphones are employed, apparently to cater for a presenter who likes to move around a lot, although in reality only one may be turned on - the other being a backup and for aesthetic reasons, perhaps. Phasing problems - one mic cancelling out the other - are a trap to be aware of if you have two open lectern microphones. For speech amplification, stick with one mic per sound source. If you want one good quality microphone that will do a bit of everything, from lectern duties to miking acoustic instruments, then a Shure SM57 or similar is very hard to go past. Some microphones have an on-off switch. These can be of limited use, and a cause of great frustration for the system operator. If your church sound system is of the set-and-forget type, then a switch on the mic is useful so that the presenter can be responsible for turning it on and off. If you have a system operator then use a mic with no switch or tape over the switch so that it can’t be turned off. Sometimes an inexperienced presenter will finish speaking, [`helpfully’] turn off the mic and then the next person to use it will find that it doesn’t work - rather, the system operator will find that it doesn’t work and everyone will turn around with dark looks to question why the operator can’t make the presenter heard. Sound operators cringe when the inevitable "tap-tap...is this on?" is heard from the hapless speaker. Everyone else seems to find this funny, for some reason. I've been in touch with a few people recently about good ways to amplify a piano. There are several factors, like the type of piano, volume level of surrounding instruments, room environment, whether it's for recording purposes or sound reinforcement or both, whether the pianist needs to be able to hear it back through some kind of foldback system, etc. It's worth experimenting a bit here to see what works. Certainly, a pair of small condenser microphones placed above the strings (if it's a grand) can work if a good position is found. If the mic installation is to be permanent then a pair of pressure-zone microphones (PZM) taped inside the lid can work, too. If the piano is an upright then a pair of microphones poking in the top through the open lid is worth a try, or even at the back of the piano, pointing at the soundboard. Another option is to use specialist piano pickups (similar in operation to electric guitar pickups), but I've not had a lot to do with those. To close this brief discussion on microphones, if you don't have regular band-based music in church services, but still have acoustic-style musicians from time to time who need some amplification, it would be worth having a small collection of good microphones that you can call on. There are several models of reasonably-priced `pencil' condenser microphones that come in a set of two - for stereo recording among other things - among them the Oktava MK-012 and the Rode NT5.
Mixers
So, you have a lectern microphone in place and a long microphone cable emerging. Next in line is some kind of level (volume) control device. This is usually in the form of an audio mixing console, (or mixer). Mixers perform a lot of tasks and are often referred to as the `central nervous system’ of a sound system. If your sound system only contains a lectern microphone, then the mixer need only be very simple. Again, they vary greatly in quality, configuration and price. The sound quality difference between a cheap mixer and a more expensive one is often quite apparent. In a nutshell, a mixer performs the following tasks:
When choosing a mixer, it’s a good idea to get one that does a bit more than you need at the moment. Features to consider include:
Note: Just as an aside; large format mixing consoles for big productions use external, dual power supplies the size of a small microwave oven and connect to the mixer with cables like a fire-hose. Power supply quality is somewhat important!
There are several mixers on the market that offer good (but not too many) features, a small footprint (how much space they take up) and respectable sound quality. Brands to look for include Soundcraft, Allen&Heath, Yamaha and Mackie, with high-end brand Midas now putting out some nice cheap(er) stuff, too. Another brand is Behringer which makes mixers that are ridiculously cheap and seem to offer okay results. An old staple, Peavey, makes competent gear but it can be a bit slim on useful features. Like a lot of things in life, the best gear is often that which has the most understated presentation. If you are shopping for a mixer from scratch, try hiring one or two from your local sound system warehouse so you can get the feel of what does what. Hire companies often sell off old hire stock, so you might find a good pre-loved audio console that is suitable for your needs. And there's also Ebay...! Note: Yamaha make some excellent small digital mixers which allow for the storage and instant recall of settings. They are reasonably good value but not a wise choice if you want something simple. Most mixers, regardless of complexity, follow the same general layout, so once you are familiar with the placement of key controls and switches, you’ll find it is the same for most others as well. One factor to consider when acquiring a small mixer is whether you have someone to operate it or you prefer a set-and-forget type of thing. If it’s of the latter type then make sure the mixer is easy to adjust in case of emergency, but out of reach of prying fingers…
Note: Automatic mixers exist that cater for lots of microphones in a system and turn on and off and up and down, automatically, as people speak into the microphones. They are aimed at conference room, courtroom and some church applications. I imagine places like the Houses of Parliament, UN headquarters and CIA operations rooms would have some kind of automated mixing system. Automatic mixers generally fall into the `set and forget' category. They are useful devices, but perhaps are of limited use in a system that needs to be as flexible as possible. I won't discuss them here rather than say that they exist.
As an aside: If your mixer is going to be moved around a lot from venue to venue then it is worth investing in or building a strong case for it, to protect it during transport etc. Those plastic/aluminium toolcases that all electronic shops seem to be selling these days are quite good for the really small mixers.
A good place for a mixer is near the back of the church building, where the operator can see and hear all that is going on. If the church building is quite long, then perhaps locate the mixer a bit forward from the back. A central mixing point (on the church axis) is good, but this is not always practical, especially if you have a central aisle. If your church has a gallery/balcony, don't be tempted to put the mixer up there – you won't be able to hear the system as well as downstairs, where most of the people are (probably). Visit a few churches to see how they do it and talk to lots of people to get ideas. If you are taking the `set-and-forget’ approach, then you may be able to locate the mixer near the front, so that the service leaders can adjust something if need be. Bear in mind that you will need to get someone sitting in the pews/chairs/worship space to tell you if the sound is okay. Amplifiers and other equipment that needs little attention once up and running can be located separately from the mixing position, if desired. This is a good idea if your equipment has lots of noisy fan noise. A well-ventilated cupboard with rear access for connecting things is one option. Glass doors are especially cool if you want to see all the flashing lights and glowing displays that adorn much of today's audio gear.
Mixers usually have a phantom power circuit for powering condenser microphones. Turning on the phantom power can often put a thud through the system so make sure the outputs of the mixer are all turned right down before activating the phantom power. Small mixers will probably have a global switch that applies phantom power to all the channels. Dynamic microphones don’t need phantom power but will ignore it if it is turned on, as long as they are connected to the mixer with 3-pin balanced XLR connectors. If your mixer has individual phantom switches for each channel, then only turn on the ones that are needed. Mixers usually have a blank strip near the faders for white tape so you can label the channels (e.g. Lectern Mic, Radio Mic, Guitar, Kazoo Mic etc.). On the subject of power, if at all possible, run the entire sound system from the same electrical circuit to keep down the risk of ground-loop hum. If your church has a fancy lighting system, then run the lights on a separate circuit to the sound. Lighting dimmers are notorious for causing excessive hum in sound systems.
There is often a desire to connect guitars, keyboards, etc. into the mixer. A description of sound systems for a full band set-up is beyond the scope of this keep it simple themed article, but I’ll give a few ideas for simple instrument applications:
- Don’t connect an electric guitar or bass straight into a mixer. You can, but if you want okay sound quality it’s wise to use a direct box.(direct injection or DI) You can build a direct box from a kit for about $50 which will be quite adequate. A direct box does several jobs but is best described as being an impedance-matching device for optimum signal transfer from guitar output to mixer input. It makes any signal source appear like a microphone to the mixer. If you are running the guitar signal over a long distance to the mixer then the direct box is useful as it will convert the unbalanced guitar signal to a balanced signal in order to reduce hum-pickup that is typical of long cable runs. A direct box also has an extra output for linking in with an on-stage/up-the-front guitar amplifier or guitar tuner. If your guitarist has a guitar amplifier that they are very fond of, then feel free to simply put a microphone in front of it. That’s how it’s usually done in the trade. Aiming the microphone (such as a Shure SM57) at the join between the dome and the cone on the loudspeaker is considered to be a good approach. The thinking behind miking a guitar amplifier is that the guitar amp is an integral part of the electric guitar's sound, and to plug the guitar straight into a general sound system will cut out an important part of the sound that the player has spent a long time attaining (a bit like trying to capture the sound of a pipe organ through the organ's electronics, without recording the pipes themselves, in the room). Bass guitars usually go through a bass amp/bass loudspeaker cabinet/direct box combination. - Players of acoustic guitars with internal pick-ups are usually happy to plug straight into the sound system via a direct box. Many internal pickups have a preamp module in the side of the guitar that has basic level and tone controls. If connecting the guitar to a sound system then it's often best to set the tone controls to a flat setting and do any necessary `tweaking' at the mixing end. If the acoustic guitar has no internal pick-up then a carefully positioned condenser microphone can be employed. Experiment with positioning – pointing the mic straight at the hole often sounds a bit dead. Books on recording technique often have useful diagrams and suggestions for suitable microphone positions for acoustic guitars. One thing to be very careful of with miking a guitar in a live sound situation is if you have a foldback speaker near the guitarist so that they can hear themselves. If you are in this situation at all then it may mean that there is just too much noise to begin with and you may need to re-plan things. Other solutions to direct miking of an acoustic guitar exist - I have had good results with the `Shadow' brand of contact `bug' pick-up that attaches to the guitar's body with Blu-tac or double-sided tape. Also works a treat on violin. Run this into a direct box and off to the mixer. - Keyboards and electric pianos can plug straight into the mixer, but a direct box (two if it’s a stereo output you want) is an excellent idea if you have a long run to the mixer. - Some form of musician's foldback is a good idea – a small loudspeaker in the band area so that the musicians/presenters etc. can hear themselves and what else is going on. A very simple example of this is a loudspeaker next to a keyboard/electric piano. Many keyboards have no or poor internal speakers and often the player may not be able to hear properly through the main church loudspeakers. Self-powered loudspeakers, as discussed below, are useful in these situations. If you have an old guitar amplifier then that can do an adequate job. The auxiliary outputs on a mixer are suitable for sending signals to foldback systems. Foldback (or `monitors') should not be treated as an unnecessary luxury. In the live music industry it receives no less attention than the main sound system. Of course, your church building's design, size and acoustics may negate the need for foldback, as long as musicians and presenters can hear themselves. A small loudspeaker near the lecturn is a useful thing so that the speaker can hear themselves and be reassured that their voice is in fact being amplified. Be aware of the fine line between over-complexity and sonic clarity. In other words – if your musicians have trouble hearing themselves because of an unnecessarily big and loud main sound system, then you may need to re-plan...
A word about signal levels: There are three main kinds of signal levels (analogous to volume) to be concerned with in simple sound system work:
Example: A typical small mixer has microphone level inputs, line level stereo inputs, line level stereo outputs and line level auxiliary outputs. It is important to understand how these levels relate to each other – line levels will need to go through an amplifier before they are strong enough to drive a loudspeaker; speaker levels are too strong to safely plug in to the inputs on a mixer. Sooner or later the subject of decibels comes up. A quick rundown: A decibel is one tenth of a Bel, named after Alexander Graham Bell, of telephone fame. The decibel (dB) is a dimensionless figure using logarithms, for expressing the ratio between two signal levels. In measuring audio signal levels on sound equipment, 0dBu is the reference level, and the signal you are looking at is measured in relation to this. A microphone signal into a mixer may be around -50dBu. Line level is around -10dBu to +4dBu. No level at all is -infinity dBu. If you look at the signal level meters on a mixer you will see that the `redline' usually starts somewhere over 0dBu, and 0dBu is near the top of a level fader's travel. The `u' at the end of dBu refers to unterminated and means that the 0dB referred to is 0.775 Volts RMS. 0dBV means 1.0 Volts RMS (these are some of the standards used in physics and engineering). Sound pressure level is expressed in terms of dB SPL – for example: an indoor rock concert may measure 130 dB SPL on your portable sound level meter. 140 dB SPL will damage your hearing. Sound pressure levels are measured with several `weightings' which take into account the way the ear responds to sound in the real world. Don't panic at all this scientific stuff, just be aware of what some of it means. It will help you to better understand mixer operation. I would strongly recommend hearing protection though, if your sound levels are high and continuous. Ears can be damaged well before you are aware of the pain. Pardon? Exactly.
Amplifiers etc.
To drive loudspeakers from the mixer output you will need a power amplifier. Some small mixers have power-amplifiers built-in. These are known as powered mixers. It makes things very convenient, but problems include extra weight and bulk as well as the possibility of increased hum in the system due to the close proximity of the amplifier’s power supply to the low-level audio circuitry of the mixer section. Some powered mixers resemble a box the shape of a small microwave oven, while others look like a normal mixer, with a bit more bulk. The box-shaped ones are often the cheaper quality ones (although the ones from Mackie seems okay) and are a bit more awkward to use than the mixer-shaped ones. Box-shaped powered mixers often suit a set-and-forget type of sound system. For a simple vocal reinforcement system in a small church building, a good quality powered mixer would not be a bad option. They are especially suitable if your church sound system is of the temporary kind that has to be set-up and removed each week (e.g. if you meet in a multi-use venue) or if you just need maximum portability. Powered mixers have a nasty habit of being full of apparent goodies like built-in sound effects processors, all to draw in the unwary buyer. Of course, such extras can usually be switched off, but we soon begin to drift from the keep it simple, make it good quality ethos. So, if you just have a mixer with no amplifier built-in, then you’ll need to get an external power amplifier. The stereo (2 channel) variety is the common kind to get. This lets you operate two loudspeakers (e.g. in left/right stereo fashion) and adjust the levels of each loudspeaker separately if you wish. Again, good quality is worth looking for. There are quite a few good brands of power amplifier - including Yamaha, QSC, Crown, Crest, EV, Australian Monitor, ARX, Mackie and Carver. Different power outputs are available depending on the model you get. It seems that an amplifier that produces about 100 watts RMS per channel would be adequate for many applications, but the type of loudspeakers used does have bearing on the best choice of amplifier. Watts Root Mean Square is the usual unit for expressing the output power of an amplifier. If you are reading product literature then you will probably see the output figure expressed as into 8 ohms, 4 ohms or 2 ohms. Many amplifiers for sound reinforcement use produce a lot more than 100 W RMS per channel and have input level controls so that you can turn them down if things are getting a bit loud. Note that it is the input level that is being adjusted: The amplifier's output will always be the input multiplied by a certain amount – to lower the output we lower the input so that it is a smaller initial signal that is being amplified. So – if your system is too loud, even though the signal coming out of the mixer is very low, then lowering the input levels on the amplifier is one thing you can do (although there is a school of thought that says to run the amplifiers up to max all the time and just lower the signal elsewhere...hmm...). On that note – it is important to set the amplifier's input levels to allow for optimum gain structure. Amplifiers often clip (can't produce a signal any bigger) at a lower input level than a mixer is capable of putting out, so if you have the amplifier's input levels set to maximum then there is the possibility of clipping the amp with a signal which is coming out of the mixer with no trouble at all (because the mixer isn't clipping yet). To get suitable settings, run some signal through the mixer (ideally pink noise from a test CD if you have one) and set the mixer's output to just below clipping (the red lights on the mixer's level display). Adjust the amplifier's input levels so that its own red clip lights are not quite on. You have now set the mixer and amplifier so that they both clip at approximately the same level. Popular opinion in the industry says that it is okay for amplifiers to clip slightly earlier than mixers – you'll probably find great debate on this one if you search the discussion forums! Some power amplifiers don't have input level controls that go low enough to tame mixers with high level outputs, so a 20dB pad (small resistor network) can be inserted in line between the mixer and the amp to reduce the signal going into the amp. Good power amplifiers have protection circuitry for themselves and the speakers, to minimise the risk of blowing anything up. Power amplifiers can create a lot of heat, so if there is a fan, ensure that it is not too noisy. Like most things, power amplifiers are aggressively marketed, and when researching various types and brands you will encounter lots of hype and jargon. Manufacturers are constantly trying to woo us with very high power to weight ratios and great efficiency. Some things are worth careful consideration. Today's amplifier design trends include seriously fancy switching power supplies, light weight, digital circuitry and network connections. Beware! Avoid using an old home stereo amplifier for your church loudspeakers unless it is of high power (100W RMS / channel or more), and even then be careful. You are more likely to damage a loudspeaker with too small an amplifier than too powerful an amp. The reason for this is that a small amplifier will run out of steam when fed too high an input signal, and will start clipping. This effectively puts direct current through the loudspeaker coils and causes overheating and driver damage. It will sound lousy, too. Domestic amplifiers will probably also be less forgiving of mishandling – connected wrongly, overloaded etc – as they probably won't have as much protection circuitry. Better to have a large amplifier running comfortably at a medium level than a small amplifier running at maximum and struggling to keep up.
Many older church sound system may be of the 70V/100V type, synonymous with telephone sound quality, tatty wood-grain column loudspeakers and long, thin speaker cables. Such systems are often seen at public outdoor events with lots of horn loudspeakers mounted on poles; paging lost children, announcing raffle results, the best scones award etc. School public address systems are usually of this type, too. This kind of equipment is good for speech transmission in installations where there are lots of loudspeakers to run through many rooms with lots of cable. They are not directly compatible with the 4-8 ohm systems which this article is generally describing, but you can usually connect the two kinds together, at the mixer stage (line level connections) or with transformers at the loudspeaker end. It depends a bit on what connections your equipment has.
Loudspeakers
Loudspeakers fill enormous books and papers of discussion. I’ll not dwell too much on them here, but if you’re starting from scratch then it’s a good plan to investigate loudspeakers at the same time as you are looking at power amplifiers, to get a package that will work well together. The common sort is the two-way loudspeaker which comprises a large round low frequency `woofer’ beneath a small horn for high frequencies. Some good brands of loudspeaker to look out for include EV, Tannoy, JBL, Meyer and EAW. Bose also do a good range of loudspeakers for auditorium use. Some loudspeaker designs comprise a floor-mounted bass enclosure, with a pole mounted mid-high loudspeaker on top (making a three-way loudspeaker in all). This is a good idea to reduce the visual impact of a large pole mounted loudspeaker, but adds complexity to the system – although many newer systems are self-powered (see below) and have a reasonable foolproof connection procedure. Simple loudspeakers for vocal reinforcement are often of a passive design, with a low frequency driver (woofer) and a high frequency driver (tweeter), similar to the loudspeakers found on many hi-fi systems. The signal from the amplifier enters the loudspeaker unit, and is then split into a high frequency component and a low frequency component. The split is done by a circuit called a passive crossover. The two signals then go off to their respective drivers. Passive loudspeakers are reasonably foolproof, as long as the amplifier driving them is suitable. A
more recent development in sound system gear is the
self-powered
loudspeaker. While the idea of having a loudspeaker with a
built-in amplifier is not unlike the humble high-school guitar
amplifier, the self-powered (or active) loudspeaker’s aim
is to do it with some sense of hi-fi. Self-powered loudspeakers, such
as those from EV, Mackie, JBL, dB, RCF, Quest and Meyer, can plug straight
into your mixer outputs if you wish and the sound quality is
generally excellent. Self-powered loudspeakers are particularly well-suited to systems that require the installation of many small loudspeakers being fed individual program material, where space/practicalities don’t permit the use of a separate external amplifier for each one. Self-powered loudspeakers are also good for musicians’ monitors - so they can hear what they are doing. . The sheer convenience of self-powered loudspeakers makes them well suited to temporary installations such as in multi-use venues or quick setups in the church hall for announcements at community lunch etc. - some models permit the direct connection of a microphone so that no other equipment such as a mixer is needed at all. Loudspeakers need to be positioned so that they effectively cover the listening area (i.e. the congregation or whoever needs to hear). Imagine a line jutting out perpendicular from the front of the loudspeaker – this is the loudspeaker axis. Aim this line at some central point in the worship space where people will be listening. You will probably have more control over the pan angle of the the loudspeaker than the tilt, unless you have a special yoke or ball-socket mount for the job. Purpose-built tripod stands (the `winch-up' variety are good) work quite well for mounting loudspeakers, or you can mount/fly them from the wall/ceiling/truss in your building, being careful to use the proper fittings for the job, including safety chains, as per your local rigging regulations. A friend in the lighting/rigging trade is a useful contact to have in this situation. A loudspeaker coming loose and landing on someone's head is not ideal. Mounting from part of the building would suit a more permanent installation, and you can get all the angles right to allow for maximum coverage. Some loudspeakers are available that are part of a light pendant fitting and can hang down above the centre of the room. These work reasonably well (be careful of feedback), but are a bit limited in their frequency range - being best for lectern vocal reinforcement. To get full range performance from them you will probably need to supplement them with some kind of subwoofer (low frequency loudspeaker) on the floor. Loudspeakers for professional (as opposed to home hi-fi) applications usually have different connections to domestic models. Domestic models often have a binding post arrangement for bare speaker wire or banana plugs (which are outlawed in some countries as a means of connecting loudspeakers). Several different connectors are seen on professional models, including XLR, Jack and Speakon. Several other connectors (e.g. EP4, EP6) exist on high-end multi-way loudspeakers but they are quite straightforward should you meet them. Speakon connectors are quite a good choice for church sound systems as they are quite different in appearance from XLR and jack connectors, which are widely used elsewhere in sound systems and could cause unnecessary confusion. If you are shopping for new loudspeakers you can sometimes choose what sort of connectors you would like.
Note: Impedance is something to be aware of if you are linking up more than one loudspeaker to the same amplifier output. Impedance is similar to resistance except that it is dependent on the frequency of the signal going through the circuit. Many loudspeakers have an impedance of 4 or 8 ohms, but if you simply put a simple ohm-meter across the terminals you’d get something different. Some elementary electronic knowledge of series circuits, parallel circuits and Ohm’s Law is useful here. In general, power amplifiers like to feed loudspeaker systems with a minimum of 4 ohms, so keep that in mind when linking up multiple loudspeakers. If the impedance goes too low then the amplifier is feeding a very easy load (like going fast in a car in first gear) and can overheat, blow something or become unstable.
Other bits
An important piece of equipment to consider is a graphic equaliser. This links into the circuit between the mixer and power amplifier (or mixer and self-powered loudspeaker). Mixers typically have insert connections that permit an equaliser to be inserted into the audio signal chain before the signal goes out to the amplifier. Alternatively, just run the mixer's output into the EQ and from there to the power amp. A graphic equaliser, or `EQ', lets you smooth the frequency response of a sound system for a given room, to reduce the chance of feedback due to the excessive reflection of certain audio frequencies. This will vary from room to room. For example; a room with a lot of glass will reflect high frequencies well, so the high frequency response of a system may need `toning down’ to sound good in such a room. If the sound is `boomy’ or `honky’ or `ringy’ or has other negative qualities then the EQ can be useful in improving the sound reproduction. If the sound system is staying in the room when it is installed, then the graphic EQ will need adjusting at first and then may not need much attention. Once you have used a graphic EQ a bit you will begin to get a feel for what feedback at particular frequencies sounds like and which frequencies are especially troublesome for the room you are in. A `ringing' sound in a sound system around certain frequencies (say, 500-1000Hz) is an example of a potential feedback issue. A good way to get started with an EQ is to have your lectern mic sound system operating, have the EQ flat, turn up the overall level until something starts feeding back (it will, eventually!) and then reduce the level of the offending frequencies on the EQ as best as you can. Generally you should only cut frequencies - boosting particular frequencies to try and `add something’ is not usually successful. Human hearing officially covers the range from 20 Hz to 20,000 Hz (20 kHz). Like many people I certainly can’t hear much beyond 16 kHz. Many initial problems requiring equalisation seem to occur in the 500-5000 Hz area (speech falls into this zone), so you’ll probably get to know this area quite well. Graphic equalisers are described here in terms of acting as overall system equalisation. Mixers have a simpler type of equalisation on each channel for adjustment of individual sources, but this is best left until after the main system EQ has been adjusted to satisfaction. A graphic equalisation device is not necessarily required – if your sound system is of good quality and the room okay you would be fine without the added complexity of an EQ. They are just something to be aware of. It should be noted that pulling out big chunks of frequency response with an EQ to reduce feedback is robbing your system of power. The first task to perform in reducing feedback is possible adjustment of loudspeaker/microphone arrangement, so that the chances of feedback occurring in the first place are minimised. Note: The topic of room acoustics - design, materials, size etc.- is quite complex and best left for another day. Simple, commonsense considerations can generally be made in order to get the best sound from the equipment you have.
Cables are an obvious part of connecting up a new system. Microphones generally use a balanced three-pin XLR connection to connect to a mixer, either via a multicore (a `snake’ containing many cables) or with a discrete microphone cable. The male end has the three pins, the female has the three holes and a latch. Get good quality cables and connectors, to keep reliability high. Multicores are not usually required for just a couple of microphones, but having a multicore is a useful thing if you plan to expand your system in the future. Once you have installed a multicore, you can then easily connect things from the front to the rear of the church without the need to run more long cables. When rolling cables, use a forward-reverse (over-under) technique to avoid the cable getting a `memory’ which makes it hard to unroll smoothly later. Rolling around your arm is a surefire way to develop permanent kinks in the cable. Don't do it. Use electrical tape or Velcro strips or similar if storing rolled cables in the same container. This avoids them all getting tangled (hopefully!). Self-powered loudspeakers require a power lead and a balanced signal lead. If your set-up is non-permanent or portable, it's worth making a loom of power and signal cable – tape the two together with electrical tape or invest in specialist power/signal cable. This means that when setting up the loudspeakers you can just run one cable out (which is actually a composite of a power cable and a signal cable).
It is worth having plenty of spare adaptors for connecting things together. It’s quite common to have a cable with the wrong kind of connector on the end. Probably the most frustrating aspect of connecting things up in church is interfacing between the domestic and professional worlds of connectors. Useful adaptors to have in your kit include: -RCA to 6.3mm tip/sleeve Jack - Most domestic sound and video equipment has RCA connections. Your small mixer may have RCA tape inputs/outputs, but if not then you might need to plug into a jack connection. Adaptors are useful here. Another need of RCA to Jack adaptors is if you are connecting a video machine’s audio to a direct box. -Female XLR to tip/ring/sleeve jack. -Male XLR to tip/ring/sleeve jack. -Female XLR to tip/sleeve jack. Even better, get a balanced to unbalanced converter. -Female XLR to Female XLR -Male XLR to Male XLR
These adaptors can be purchased, but it is often cheaper to make your own, if you are handy with a soldering iron. Some cheap pre-made adapters seem good at introducing hum into a sound system. Wiring diagrams are useful here - often there are diagrams in sound equipment manuals to help with how to connect up the wires when soldering connectors. Catalogues such as from Dick Smith Electronics have a useful data section which has lots of helpful info here. It is worth getting good quality connectors, such as those from Neutrik, Switchcraft and Alcatel. XLR and 6.3mm jacks (such as guitar leads) are pulled out and plugged in a lot so need to be robust. I prefer the Neutrik type connectors that dis-assemble without tools by simply unscrewing the plastic boot.
Note: 6.3mm and 6.5mm jacks are essentially the same thing, but beware that there is the 3-contact (Tip/Ring/Sleeve, such as on headphones) type and the 2-contact (tip/sleeve, such as on guitar cables) type, according to what you need to do. Some sound gear uses 3-contact TRS jacks like headphone jacks to connect single channel balanced signals. Once you have a grasp on what you are connecting to what, you'll get the hang of the different kinds of connectors.
When planning the assembly of a sound system, draw some signal flow diagrams so you can clarify what is connecting to what. E.g. Microphone -> Mixer -> Amplifier -> Loudspeaker. This is helpful for everyone, especially those keen helpers who know a jack from an XLR but are not sure what goes where.
Many pieces of equipment such as equalisers and power amplifiers have rack ears on the front, which means that they can be mounted in a rack of 19" width. This 19" is an industry standard and nearly all rack mounted gear will conform to this standard. If you have a small collection of devices for your system that are rack-mountable then it may be worth building or buying a rack mount `sleeve' which will house the equipment and provide some protection. Install a powerboard in the back and you'll have a rack of gear with only one power lead to connect up the the mains. Don't cram too many things like multiple amplifiers into the one small rack – they may not get adequate ventilation and the rack will be heavy to lift (depending on the model of amplifier).
In use
When you have new equipment, allocate ample time for people to get used to it. Microphones need to be used properly to get the best out of them - if a gooseneck lectern microphone is being used, it will usually need to be height-adjusted to aim at the speaker’s mouth. Inform presenters on the best way to position it so they can do it themselves. It is common for presenters to not adjust the microphone's position for themselves, and subsequently sound faint because they are too far from it. The operator can then only turn up the level a certain amount before feedback occurs. It would be great to have some magical microphone that picks up sound from all around, while sounding fantastic, without feeding back. Such a device is either completely fictional or very expensive. Assuming a certain level of confidence on the operator's part, don't let the presenter give a "tap, tap, is this on...?" at the beginning. Ideally the presenter will ensure that the microphone is in the correct position, project their voice and ignore the mic's presence. This of course requires trust that the sound operator will bring the mic up on the mixer. From an operator’s perspective, the sound gear is there to reinforce the original source, not make up for nothing in the first place. Carefully set the overall system level so that people are able to comfortably listen without having to strain or be deafened. Getting this level correct can take some trial and error, patience and diplomacy. People in the pews who always say they can’t hear may need to be asked to move further towards the loudspeakers. Some churches have a supply of wireless headphones available for those who need something `extra'. If you have lots of people with hearing aids, then an induction loop for that is a good plan (you may be required by legislation to have one). This is basically a loop of wire that goes around the perimeter of the church building, driven by a special amplifier. Hearing aids are then set to pick this up as an electromagnetic signal.
Extra loudspeakers (e.g. towards the rear of the building) should not be added without thought. For proper sound quality and no echo, a delay system should be considered, which adds a degree of complexity to our `simple' system. As an aside: Professional sound systems with lots of loudspeaker components rely on some kind of system controller, or loudspeaker management processor, such as those made by BSS, Dbx, XTA and Klark Teknik. These devices let you adjust various delay, equalisation, crossover and filter parameters. Such processors are expensive and I wouldn't be mentioning them here, except that, at the time of writing, a company (in)famous for making very cheap equipment has just put out such a machine at a really low price. If you are considering a sound system with lots of independent loudspeaker components in different places then some kind of system controller would be very useful. In a large room a distributed system involving many small loudspeakers placed throughout the room is more effective and elegant than just blasting from the front with the hope of reaching the rear while risking deafening the front. This goes beyond our simple system ethos, however, and is only worth considering if you have a really big or difficult space to fill with sound and need some kind of specialist solution.
Keep an eye on the signal level meters on the master section of the mixer to ensure that they don’t go into the red, as too high a signal can lead to clipping and distortion which will sound bad and result in damage somewhere down the line. Note the comment earlier about setting amplifier input levels. The amount that you can go `into the red’ without achieving clipping, distortion and damage is referred to as the headroom of the system. In a small church meeting you may find that the signal level meter hardly registers at all. This is actually not always ideal as it means that the mixer is not operating at a healthy signal level (lower signal/noise ratio). If possible, turn down the input level controls on the amplifiers and turn up the mixer so that the mixer's output meters register a healthy signal. Likewise, red indicators on the individual channels light up when the sources are coming into the mixer at too high a level (commonly and colloquially described as `hot'). Lowering the channel input gain is the first step in solving this problem. In some cases you may have the gain turned all the way down, and the signal is still too hot. In this case see if you can lower the level on the source.
With regard to equalisers, whether the on-board mixer EQ or a separate graphic EQ, don’t be tempted, for example, to add lots more bass to make things sound cool. Chances are it won’t sound better. EQ is intended to help achieve a `natural’ sound from the equipment you have, rather than for obvious effect. The amount of bass you can get is limited by your loudspeaker system, so don't try to get more out of a small loudspeaker by boosting the EQ. Generally, to get lots of bass, there is no substitute for a large loudspeaker, moving a lot of air, despite what the advertisements would have you believe.
One of the best bits of advice to churches with sound gear is this: If, during a service, you can’t hear the speaker properly, or there is feedback, or another problem, DON’T turn around and give the sound operator a dirty look ! Unless they have fallen asleep, I am sure that they are aware of the problem without the need for `traditionalists’ and `wise guys’ giving looks of disapproval of 'all this new gubbins'. If the operator is new to the job then by all means have an assistant nearby to offer help, but the poor soundperson doesn’t need the whole congregation glaring at them. By the same token, it is up to people to be familiar and patient with the equipment, so that the inevitable problems are kept to a minimum. Sound systems are not all rocket science, so don’t plead ignorance when offered instruction in how to use the equipment effectively. A certain amount of care, alertness, listening and thought is required, but there is a good measure of common sense to the whole thing. Another point to mention is that the same operator shouldn’t have to do the job every time. It could happen that people who operate the gear all the time feel that they are not able to participate in the worship due to the inevitable distractions that sound gear brings. Sound system operating is a skill to work on. There is always more to learn, more to hear. Aim to be smooth. Don't continually have your fingers hovering over the controls. Relax. Listen. Anticipate.
Radio Microphones
Wireless (radio) microphones seem to have a long-standing place in many church sound systems. They are convenient for people who move about as they speak, and are often seen in `spontaneous prayer’ sessions when a hand-held microphone is passed around to people in the congregation.
The only benefit of wireless microphones is that they let the presenter/performer/preacher/leader move about freely as they give their address. It may sometimes be impractical to run a cable to where the presenter is - such as in television broadcasting where the talent needs to walk on and off the set quickly - but in reality probably not often. Much of the time, a normal wired microphone will do.
Never take wireless transmission of audio for granted.
Wireless mic sound quality is very good, but in terms of sonic transparency and reliability, a normal, wired microphone is preferable to a wireless one anyday. Radio microphone transmission technology is a science in itself, and while today’s systems are pretty much of the `plug and play’ variety, it doesn’t make them trouble free (although the stories you hear about picking up cab radios etc. are not so true anymore). Everyone claims to know someone who knows someone who went to the bathroom with the mic turned on. A typical wireless microphone system contains a transmitter (either in the form of a hand-held microphone or a belt-pack for lapel/headset mics) and a receiver, which usually takes the form of a small flat box with two antennae attached. One complete system will let one person talk. If you want to have two people in the same place talking on two wireless microphones simultaneously, then you need to employ two complete systems, on different frequencies. Some units allow up to (e.g.) four people to talk simultaneously, but are really only four separate units incorporated into the same box. Good wireless systems start at about $1000 and go up from there. Anything less than this and you must be careful. You get what you pay for. It’s a lot to pay for the convenience of wireless, but reliability is important. Cheap radio microphones often sound very `tinny' and are prone to dropping out. Most reputable mainstream brands of radio microphones, such as Sennheiser, Shure, and Sony, offer `budget’ systems (~$1000-$2000) as part of their product range. In my experience these budget systems can offer very competent performance - lacking only the physical robustness, compactness, frequency adjustment and very high radio/audio quality demanded by touring theatrical productions, rock concerts etc. There are some brands like Lectrosonics that focus on broadcast applications, where the emphasis is on extreme reliability and robustness. In my experience their performance and radio range is fantastic but they are expensive and probably not justified for most church gatherings. Some brands make a transmitter that fits straight onto a regular vocal microphone. It is a good idea if you have a favourite microphone that you’d like to use as a wireless, but there is no practical cost saving, as you need to have a compatible receiver to complete the system. Better to buy an all new system with a hand-held mic transmitter and retain the old favourite for normal, wired duties. For best performance, position the radio receiver in a position close to where the transmitter is being used, with a line-of-sight transmission path. Proper wireless systems have a diversity design (indicated by the two antennae on the receiver), which means that the receiver has two separate radio circuits to pick up the signal, and chooses the best quality one. This ensures that, as the presenter moves around the room, the system is able to offer the best possible reception, minimising drop-outs (when the radio transmission is lost due to a multi-reflections, phase cancellation, etc.). The antennae should be physically arranged so that they are not parallel. Nearly all radio microphones operate in the UHF band, and are fussy about major obstacles in the transmission path. Having a spare, wired microphone close at hand is a good idea in case you have radio problems and need to change to a backup option. Decent brand systems have optional antenna boosters and a splitter unit (sometimes termed an antenna distribution system) that permits the running of several receivers through the one set of antennae to save space if you are using several systems at once. If using four or more systems simultaneously then I highly recommend using an antenna distribution system – assuming the individual systems are all of the same brand and compatible. This method of setup means that you no longer have a pin-cushion of individual antennae from each receiver which can lead to unnecessary interference problems. Antenna distribution systems also allow you to locate the actual antennae remotely from the receivers (linked by a signal booster and co-axial cable), so you can minimise the distance that the radio signal has to travel from the presenter's transmitter. For example, I have worked on theatre shows where the antennae were hidden in the set, and connected by co-axial cable to the receiver rack located in the wing (side of stage). Unless you have a set-and-forget sound system with no dedicated operator, a good approach to the use of radio microphones is to turn (all) the transmitters on at the start of the session. This allows – especially wise if you have multiple systems – for checking that they all work together happily and that there is no interference. Some transmitters let you lock them on, preventing accidental turn off. Other features on some models include separate audio mute switches and the useful ability to adjust the transmission settings without actually transmitting. Higher end models usually just have a simple on-off switch. Leave transmitters switched on, and then use the mixing desk to turn the audio on and off as you need. Keeping the transmitters turned on for the duration of you session has several benefits:
Note: People who have had nothing but trouble-free experience with radio microphones may think I'm being a bit paranoid about reliability issues. Perhaps I am, but I'm just making sure you are aware of what can go wrong... If you are using a belt-pack type of transmitter, then you will need a microphone to plug into it. Headset microphones are the best sort of microphone for wearing but they are not always discrete enough (unless they are of the high-end $$$ type from the likes of Countryman or DPA), so lapel microphones are a common choice. There are various types - cardioid, super-cardioid, omni-directional. Cardioid mics are a good choice, as they will pick up the presenter’s voice very well if aimed properly (i.e. up at the mouth.). Omni-directional microphones will pick up sound from all directions. This can cause lots of feedback, so they require good positioning and a careful system operator. Note: If you are able to use headset microphones - i.e. they are available to you and the wearer is happy about it, then do it because headsets offer far better sound quality and potentially less feedback than a lapel mic. Some people may feel a bit self-conscious (or make a point of appearing self-conscious) with a headset, as if it makes them into a `performer’. The typical us vs them comments ensue, with the accompanying hand gestures. This is an understandable concern, however, with a good attitude and approach it needn't be a hindrance. Ultimately: do they want to be heard clearly or not? Get over the performer hang-up! Once you hear the sound of a good headset a lapel mic is hard to go back to. The extra-discreet headsets now available help counter the `Madonna' look. If you are planning a special event and would like to try a good headset then hiring one for the occasion would be a good idea. I'd like to see headset mics adopted more often as lapel mics don't work so well if the presenter turns his or her head around too much. Lapel-mounted mics have their place - particularly in tv studios or for electronic news gathering in the field, but for indoor sound reinforcement they are a bit limited and problems with feedback and poor response are not uncommon. A novel take on the lapel mic idea is a current mic/transmitter design from AKG that sits in the breast pocket like a pen (perhaps inspired by old thrillers like The Conversation?). Transmitters usually have a gain control for adjusting the level of the microphone audio into the transmitting circuitry. Set this carefully (shout into the mic at typical mouth-mic distance and adjust the transmitter gain until the peak light just comes on) as if it's too high then you may get distortion in the transmitter which can't be rectified by the sound operator at the receiving end. Wireless microphones all use batteries in the transmitters. The 9V type is commonly used, with better models using the AA and AAA variety. You can easily expect several hours of continuous use from a fresh battery, and the AA powered models seem to last longer than the 9V ones. Dry-cell Alkaline batteries are the best, but their ongoing replacement can get expensive. If you must use rechargeables, then use the NiMH (e.g. Varta) type, which supposedly don’t have the memory problems of NiCd batteries. Make sure they go on the charger after each session. Due to reliability issues, rechargeable batteries are generally not recommended for use in wireless microphones in the professional audio environment. Eveready and Duracell make so-called `professional’ alkaline dry-cells which seem to last a long time and can be purchased in bulk for cost savings. Battery status indicators are common on radio transmitters, and similar indicators on receivers are now being seen among the lower priced systems, although they are more of an indication than a definite gauge of remaining battery life. It can be convenient or nerve-racking to be operating sound for a presenter, and know approximately how much juice is left in their radio battery. Such a facility is not a bad idea, but it is a good idea to put a fresh battery into the transmitter before each session for peace of mind, unless your sessions are short – where you will probably get several runs before the batteries are flat [I don't work for a battery company; batteries have a mysterious life of their own, and that is a variable you can do without]. Battery meters seem much less useful if you use rechargeables, due to their flatter discharge curve (i.e. it all looks good then suddenly drops off). Slightly used batteries can be used again for rehearsals or non-critical situations. Otherwise, save them up for guitarists who need them for their effects pedals, or for instrument tuners, portable music players, Maglites, multimeters, etc.
Note on licensing and interference: Wireless microphones of the kind discussed here are covered by a class licence issued by the Australian Communications Authority. The licence is the Radiocommunications (Low Interference Potential Devices) Class Licence, 2000. Class licences are convenient because they allow people to use certain radio equipment - such as wireless mics, cordless phones, mobile phones, radio-controlled models, garage door openers, etc.-without the need for individual licence applications and licence fees. As mentioned above, most wireless mic gear sold today operates in the UHF band (520-820 MHz). Older equipment may be of the VHF type (174-230 MHz). The VHF band is subject to increased intrusion from digital television broadcasting, so don’t be tempted to buy that cheap second-hand or ex-rental wireless gear if it operates on the VHF band - you may find it useless due to television interference, and the seller will be only too happy to get rid of it. Actually (to put a damper on the whole wireless microphone thing), digital television broadcasting may yet prove to be an enormous headache for users of wireless microphones and the like. There is only one electromagnetic spectrum and it seems that governing bodies are keen to sell off lots of it for commercial use, without providing space for low power radio transmitters of the kind described in this article. Digital broadcasting (i.e. of television)takes up much less bandwidth than regular analogue transmission. Nearly all the wireless audio gear available today is analogue. Digital wireless microphones are starting to appear on the market, but the transition might be slow (maybe ten years or so) if it is inevitable. I suspect that governments will need to be lobbyed by wireless equipment manufacturers who in turn will need the support of the audio-visual community to guarantee the provision of `free air' for radio mics. On that note, when shopping for a UHF wireless system, it’s worth spending a bit extra and getting one with `frequency agility’ which means that you can adjust the frequency (within a small frequency window) on which the equipment operates. Most modern equipment has plenty of adjustment facility, even in the cheaper sets. Frequency agility means you can adjust your equipment to avoid interference from other sources. Modern wireless gear often includes some sort of frequency scanning facility to enable the user to choose the best frequency for microphone transmission. If you are operating several radio systems at once then frequency agility is essential – you may have all the radios operating happily on their own but when you turn them all on at once you may find that they interfere with one another due to frequency harmonics. If this happens then it is very handy to be able to make adjustments to the frequencies of individual systems to reduce the interference problem. I have found that data projectors can emit spurts of electromagnetic interference that gets into wireless systems and makes lots of awful noise, so be aware of the possibility. Like I said: Never take wireless transmission of audio for granted. Being familiar with the frequency on which your equipment operates is a useful thing, particularly when you are sharing space with other users of wireless gear, such as at large events. Media news camera operators often use wireless microphones to record the presenter's speech and if you are in a situation with media at an event then be sure to liaise beforehand to ensure there won't be a clash of radio transmission. Having to re-adjust things at the last minute can be stressful, and to be fully prepared with knowledge of relevant frequencies presents a friendly, professional impression to visiting technical folk.
Tape recorders, CD players etc.
There is often a desire to record the sound for the purposes of archiving sermons, critical listening etc. In terms of conveniently making one recording to listen to in the car on the way home, the humble compact cassette is probably still the best thing to record on to. For greater audio quality, a Minidisc recorder is good, offering a sound nearly as good as CD. The advantage of Minidisc is that it is possible to record continuously for quite a bit longer than on a cassette. Also, cranking out cassette duplicates from a Minidisc master will yield better quality copies. However, when it comes to mass-production of the recording, I think the best option is to record the event to computer hard disk, which can then be used as a source for burning CDs or later editing. Even really old computers can do simple recording. My current set-up for stereo recording is an old Apple G3 Powerbook with Toast software and a built-in CD writer. The Powerbook is equipped with a stereo line-in connection which is not available on many laptops - if looking for an audio-ready Windows laptop, check it has three audio sockets: Headphone-out, Mic-in, Line-in. Freeware audio editor software like Audacity works on most kinds of computer and lets you record for hours until your hard-drive is full, then export as an MP3 file. Standalone CD recorders, flash-memory recorders (and also, possibly, combination DVD hard drive machines) are also a good idea, especially if you want to have a back-up recording system in case of computer crash. With duplication/editing in mind, having the recording in standard WAV or AIFF format to begin with on CD or hard disk makes it straightforward to transfer elsewhere in the digital domain, such as to MP3 for podcasting. Transferring MiniDisc to CD is a bit more of a haphazard process. Make sure you keep an eye on the record levels, especially with a digital recorder (Minidisc, computer, etc.) as clipping from extreme levels sounds pretty ugly and will be in the recording to stay. If it's a sermon you are recording then get the person to speak at the mic beforehand to enable you to set the best recording level. With digital it's generally good practice to run record levels a bit lower than you might with regular old fashioned analogue audiocassette. Some digital recorders have built-in limiting to reduce the chance of clipping from excessive levels, but it's good to not have to rely on this. A good small mixer will have a RECORD-OUT connection, often in the form of domestic RCA terminals, to enable linking to a suitable recorder. If you have a mixer with no such facility, then look for a way to connect the main (line) output to the recorder. If you are going from a balanced (i.e. XLR) output to an unbalanced input on a soundcard, it's highly recommended that you use a balanced-to-unbalanced transformer adapter, rather than just soldering up an adapter by shorting the cold and earth pins on the XLR connection. With the latter method you run the risk of hum in your recordings and you've already negated the benefits of balanced outputs. A USB or Firewire audio interface with both balanced and unbalanced inputs is an excellent idea. Of course, Firewire audio interfaces, though quite expensive, are handy if you wish to record more than just two tracks at once (USB 1.0 interfaces are generally only designed for two tracks, but the newer USB 2.0 interfaces show some promise). A comment on more of a personal and philosophical note: I have been in situations where I was operating sound, and some stranger (relation or friend of someone in the band etc.) has come up at the last minute with a portable recorder in hand, expecting to plug into the REC OUT of your mixer and record the gig for themselves. It's okay to refuse their request, unless it's something you've planned for. From the practical side of the argument; they have turned up at the last minute, probably need an adapter from you to connect their little machine up, and might hang around in an irritating fashion while the session is in progress, complaining that the level to their machine is too low. This can be a stress, so say no if you're not happy. The other aspect of this refusal is that in recording something so casually they are immortalising your mix and the sound through the system that night. Maybe it's no big deal at all, but some sound engineers are bit sensitive to that kind of thing. Be respectful. If you are the one with the portable MiniDisc who wishes to connect to the mixer and record the show, ask well in advance and don't just presume that it will be okay, even if technically it is quite possible. Remember: Line level output implies a low level signal that is used to feed a power amplifier, tape recorder etc. Speaker level output is the output from a power amplifier and is much too strong to put anywhere except into a loudspeaker.
CD players are commonly used to provide music during the meeting. Like cassette players and Minidisc machines, they have a line level output, usually in the form of red/white RCA connections. Using an RCA to jack converter, you can connect them up to your mixer, which may have dedicated stereo inputs, or just use two spare channels and adjust the pan controls to get the left to the left and the right to the right. Pan is a bit like the balance control on a domestic stereo amplifier, and indeed the term balance is often used in place of pan if your mixer has dedicated stereo inputs. The mixer's stereo inputs may even be in the form of RCA connections, which makes things easy. If for some reason you are using an RCA to XLR (microphone-type) converter to connect your CD player to the mixer, ensure that the mixer's phantom power is turned off [to those channels], otherwise you can cause damage, and will get a funny oscillating sound through the sound system. Domestic CD players are not well-suited to use in public-address systems, as they have small buttons, slow, flimsy mechanisms and hard-to-read-in-the-dark labels. In the world of cobbled-together systems however, it is often all you have, so it may pay to clearly label the Play, Pause, Forward, Back, etc. controls with white tape to ensure ease of use. If you are making a serious investment in new sound equipment for your church, it may be worth considering a professional or dj quality CD machine which will ideally have big visible controls, proper track-cueing facilities and a rugged construction to ensure a long time of trouble-free service. It is tempting to buy a cheap DVD player that does the job of both CD and DVD movie playback. Be aware that many DVD machines are a bit of a fiddle when it comes to just playing a CD, as they have a menu structure that can make CD track selection less than instant.
To conclude this section on church sound, remember: aim for simplicity and good quality. Don't get into a situation of chasing your tail – when you need something louder here to get over something louder there. Wonders can often be worked by turning things down. The best compliment I have received as a sound operator is when someone came over to say that they weren't aware that I was there. Transparency.
Some useful websites for sound stuff: Pro Sound Web: www.prosoundweb.com Rane Professional Audio Reference: www.rane.com Contains a wealth of information on audio terms and a degree of humour too. E.g. DED (pronounced "dead") (dark emitting diode) A variation of LED technology used exclusively by the CIA for clandestine equipment. Also popular as power-off indicator. Meyer Sound’s discussion of speech intelligibility: www.meyersound.com/suppo rt/papers/speech/intro.htm JBL Loudspeakers: www.jblpro.com Go to the technical section to see detailed papers on sound system design. You need your brain in gear for this one. Mackie: www.mackie.com Mackie is a US sound gear company that cater well for the church sound market, especially in mixers. Most of their mixers lie near the high-end of the `budget' range. They have some kind of online magazine that discusses various topics. Many companies’ websites have provision to download the instruction manuals for gear so that you can read up on something before deciding to buy. Mackie manuals are quite humourously written. Mix Online: www.mixonline.com An online version of the excellent US magazine `MIX' with lots of interesting articles, particularly on the high-end of the sound system and recording field. Don’t be put off - there’s some good wisdom to be found here. Experiencing Worship: www.experiencingworship.com/arti cles/sound A good assortment of articles on the use of church sound equipment.
2) Projection and visuals
I’m a bit of a fan of the hymn book. You can burrow into the book and read the song without having to stare straight ahead at an overhead screen and look happy even if you are not. Same with the church bulletin and the liturgy (if you are using any). To me it’s like having your own storybook that you can follow along with.
Projecting words to songs and liturgical responses is a very common thing in churches and the overhead projector (OHP) is something of a staple. Some people put coloured film on the main lens to change the background colour from the usual white; some put a rectangular cut-out template on the lens to limit the size of the blank image area; some people use two projectors and a dj-style lighting dimmer to cross-fade between two. Slide projectors are also useful. For evening services where there is a low level of interior lighting, many projectors can be used (it seems there’re often little-used slide projectors in people’s attics etc., waiting to be discovered) to make the church into a picture gallery to inspire an atmosphere of worship (for that special 70s feel, maybe!). Words to music, prayers, quotes, anything, can be laser-printed onto paper and their photo taken with a camera using black and white film. Fix the film in a darkroom, put the negatives into slide frames and you have means of projecting white text onto a dark surface without the light spill of an overhead projector.
I don't wish to place too much emphasis on video projectors, partly because they are quite expensive (although not what they were) and partly because I believe that they don’t necessarily encourage creative thinking in the use of technology in church. Some churches seem to view the acquisition of a video projector as the pinnacle of achievement. An example of this is when I see churches using an OHP for words to music, then get a video projector and use it for exactly the same purpose, except that this time the words appear on a blue background with a nice border. AND WHO INVENTED THOSE WRETCHED BULLET POINTS???!!! Well and good if the projector fell off the back of a truck (with its lamp intact), but not really worth spending thousands for. Perhaps they are a bit like 4WD vehicles – you buy them for the `street cred', psychological comfort and prospect of what they can do but rarely actually exercise these abilities. Video in church has enormous potential, and I have several friends who are very keen on (and good at) high quality video editing and production. The video projector definitely has a place, but is not the only way to do it. I believe that `having video’ in church, as opposed to `showing video’ is important. `Showing video’ can imply everyone looking to the front while an excerpt from the latest installment of `Transformations’ is shown. `Having video’ implies that moving images are used (for example) in a way like still images are - to make up a multimedia gallery. Having video doesn’t mean “everyone face the front and shut up”, but “look around you”. For this you don’t need a big video screen at the front, but several old TV sets linked up around the room would do a good job. I’ll leave the concept of `having video’ vague enough so that you can go away and think creatively about what is possible. For those considering purchasing a video projector, I would go as far to say don't get one until you have something decent and creative to display on it. If you get one with the view of `getting into multimedia stuff later on’ then it may never happen, and it'll just be song lyrics on blue backgrounds. I don't believe that the convenience of having all your song lyrics on PowerPoint instead of OHP transparencies is worth the cost of a new projector plus computer, despite plummetting prices. Of course, if you had to choose between buying a projector and hiring one for special occasions, it may make much more long-term sense to just buy one - but is it really the best thing to spend money on? For starters in creative inspiration, check out www.visions-york.org, www.osbd.org, and www.freshworship.org.
For those who think I’m opposed to video projectors, I’m not. They’re great. I just get sad when churches are miserable about not being able to afford one, when there are alternative ways to display video material.
For those wanting to go down the path of video projectors, here are a few practical details. Technology changes at a great pace so I’ll be a bit general. Many video projectors sold these days are of the LCD or DLP type, which refers to the method of electronically projecting the image. DLP is supposedly newer technology than LCD, but not universally better. The picture from a DLP machine lacks the `screen-door' typical of LCD but there have been some issues with early DLP machines: Some people have felt ill from seeing unintended rainbow effects in the picture due to the way the projector's optical system works. The three-tube Cathode Ray Tube type, which offers a great picture once set up properly, is not seen so much any more. Flat panel LCD units that sit on top of overhead projectors don’t seem too common anymore either. Video projectors have a powerful lamp that is very expensive to replace (~ $500-$1000), and there are often built-in speakers for playback of audio from a video program. Keystone correction (self-explanatory once you see it) is usually an included feature, although correction on the horizontal axis is found only on higher end machines. The light output is specified in ANSI Lumens, and 1000 seems to be a recommended minimum figure. Some projectors are designed more for business presentations (i.e. graphics – charts, tables etc.) and may not have as high a quality video display system as a home theatre type of projector. To play a video program you usually just need to plug the video player into the video and audio inputs on the projector.. To display the output from a computer (e.g. a PowerPoint presentation), you just plug the screen output from the computer into the [VGA, DVI or whatever] port on the projector. Old laptops are often quite suited to running these displays, but if you have a PowerPoint presentation with fancy transitions they may not be very smooth if the computer’s graphics ability is not up to it. Computers with an RCA or S-video graphics output can be plugged into many recent model televisions as well as projectors (actually switching the computer to output to the TV-out port can be cumbersome, depending on your system. On my Thinkpad it's a pain). On the subject of picture resolution, many projectors use an SVGA 800x600 standard, whereas higher end machines use XGA and XVGA. Sales talk can be misleading, and it appears that the "futureproof" sales pitch which says that SVGA will be obsolete soon is a trap to be wary of. PowerPoint is a common program to use for presentations, and some people dread sitting through such presentations because they can get a bit `samey', due to the extreme ease with which it is possible to make your show boring. New users of PowerPoint are often distinguished by an overuse of busy bullet points and a different kind of transition for each slide change. Use restraint and exercise a less-is-more approach if you believe in that. I do. Keep on the lookout for different presentation methods and software – Apple's Keynote (part of the iWork suite) is good, and I've heard recommendations in favour of Presenter from Melbourne-based Discovery Systems. Good software supports a proper dual-screen arrangement with the presentation running on one and preview/lecture notes on the other. Adobe Reader lets you scroll through slides that have been prepared with Acrobat. The current Acrobat has decent slideshow creation tools. One headache is with software cross-compatibility. Picture this scenario: you prepare your slide show on your home computer, complete with animations, sounds and movie clips. You save it to CD-ROM or USB key, etc. and load it on the church machine, only to find that the movie clips won't play, or the sounds are jerky or the automated transitions don't happen. This can be due to different software versions or just what I call the inherent dodgyness of computers. A good solution is if you can prepare your show on a laptop and bring that to church to connect to the projector, or have a church laptop made available for those who don't have one of their own. Can't afford a church laptop? Perhaps you should have thought of that when budgeting for a projector. Expecting everyone to use the same version of PowerPoint on their personal machines is a big ask. What if there are Mac users, Linux users or Windows-phobics? Some projectors have facilities to run a slide show from a PC card slot, using proprietary presentation software. This is an okay solution, and you can get away without a computer for the actual presentation, but the software is fairly basic and won't co-operate with fancy animations and the like. Another - slightly upmarket - alternative for a continuous picture slide show is to assemble the pictures in software like Apple iMovie or Adobe Premiere, add music (traditional software like PowerPoint and Keynote is a bit slack on letting music span over multiple slides), put the whole thing onto DVD and then play it on a DVD player at church. To smoothly fade between video and computer display, on-the-fly, you really need a video mixer and in some cases a scan converter. I am very keen on finding a low-cost way to avoid having multiple signal cables running to the projector (e.g. VGA, S-video, video etc.) and a small box that converts S-video and video to VGA is available, but I am yet to try one. For long video cable runs it may be worth using baluns (impedance matching devices) which will allow you to run S-Video or VGA signals over Cat5-type cable. To effectively connect your video machine’s audio to your church’s public address system an isolation transformer (or a direct injection box from the guitar department) is a good idea, otherwise the sound quality may suffer - you may get a sound that is all `middle’ with little bass or treble. This is due to an impedance mis-match between the video’s audio output and the mixer input (particularly if it is a domestic video machine). Things can get complex and very expensive. If you decide that you want to have video material on several small TV screens placed around the room, there are several ways of linking them up. You can `daisy chain’ them with antenna cable, using various adapters, RF modulators and splitters (stores such as Jaycar can help here) to help solve connection problems caused by a mix-and-match collection of old TVs. If you are handy with a soldering iron then a kit is available (in Australia, at least) for a device that will take a video signal and broadcast it over a short distance (~20 metres). All you do is connect it up to your video player and tune in all your TV sets to receive it.
Desktop and laptop computers are useful items for displaying images and other worship materials. In an intimate session you can use a computer as part of an installation, where people are invited to stop and take in what is on the screen. Flash animations, short video clips, text, pictures and sound can aid in the meditative theme and are limited only by your imagination and what gear you have available. The online Labyrinth (www.labyrinth.org.uk) is an example of what can be interactively displayed on a personal computer. Many digital still cameras have a simple movie mode that lets you shoot video that can be shown on the computer in Quicktime or a similar program. Note on music copyright: There are some music copyright issues involved in the playback of recorded music in a church meeting. I think it's common for churches to naively assume that as long as they are not making any profit from the meeting, then they don't need to worry about copyright. I also believe that many churches are adequately versed in the copyright issues regarding sung chorus music but are less aware when it comes to copyrighted recorded music. Here are some points as I understand them (for Australia, anyway).
3) Alternative equipment placement ideas
Up to this point I have assumed something of a conventional sort of church session in terms of where the equipment (such as the mixer etc.) is positioned. For those who are a bit more confident in the operation of sound and visual gear then here are some other options: I have attended services with large amounts of video-loop material and a dj-style sound system. The control equipment was located on a table in a darkened offstage-left position, so that the leader could actually present from that location. This was cool in that you couldn’t immediately see who was speaking, but could hear them. It also brought the operators closer to the action rather than stuck up the back. Sometimes an approach like this is good as it allows the `technical crew’ to feel involved with the worship rather than just accessories. The technology-is-the-focus debate aside, having the audio-visual control gear in some place of prominence can add to the feeling of involvement and participation for the congregation, rather than having them made to feel like consumers. Loudspeaker placement can also be flexible, but remember to bear the following in mind: The purpose of amplification is to let a presentation be easily heard and understood. Loudspeaker placement has to take this into account. A microphone in front of an operating loudspeaker will cause feedback problems. Be particularly aware of this if you are using a hand-held radio mic that is being handed around the congregation. Intelligibility of speech can be hindered by many loudspeakers scattered around the space in such a way that the sound delays caused by different listening distances produce lots of echo effects. Large systems using many small loudspeakers often have a delay system in place to allow for correct time alignment so that everything sounds `in sync’. The sound of a system in an empty room will sound different to the sound when the room is full of people. People absorb sound. For this reason it is a good idea to mount the loudspeakers above head level.
Your worship space doesn’t necessarily have to have an obvious `front’ and `rear’, as long as it’s clear where you’d like people to be (initially, anyway). The lots-of-televisions approach to displaying video stuff means that things can be all over the room, but even a main projection screen could be centrally overhead, flat on the ceiling, or on the floor - in fact, why use a screen? Just project straight onto a suitable surface. Projectors with a suitable zoom as well as focus are useful here. If you are using white hanging sheets as screens, take the necessary fire precautions - fireproof-sprayed sheets are a good idea.
Copyright © 2006 Alex Wegman
A Tasmanian-Melburnian now living in the UK, Alex Wegman connects leads, slides faders and listens carefully; all in the pursuit of clean audio. He entered the field of sound engineering by way of a roundabout route, starting as a percussionist in various ensembles, church and musical theatre, before studying science, electronics, music production and mixing sound for local gigs. A large amount of Alex's involvements include system engineering for theatre, corporate, music, television, creative worship and special events as well as mixing live sound. alexatsoundorganic.com
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