How to tame your church sound system

Stephen Carter

 

Once upon a time a church sound system was a straightforward affair: a few column loudspeakers on the wall which usually worked. It didn't sound great but most people could hear the preacher wherever they sat. The church officer switched it on and off with one switch and that was that. Although modest in what it did, such a system would usually have been installed by a qualified person who knew what they were doing, and it worked.

Then sometime in the 1970s or 80s the church music group or worship band came along with their sound systems and everything changed. The tinny-sounding systems of the 60s were ripped outand the loud, sometimes very loud, sound systems came in their place. But something else changed. It was not always possible to hear the preacher properly any more. The people at the front were frequently deafened whereas people in odd corners and at the back couldn't hear properly at all. Often the congregation would be tortured by feedback or had to endure a constant background of squeaks. So what had gone wrong? The usual problem is that the work of the professional had been usurped and replaced by the works of the enthusiastic amateur who was often less than expert.

The purpose of this article is

(1) to give some idea what common problems are and how a competent professional installer might handle them

(2) to give the reader an idea of whether you should go it alone or whether you really need an expert on the case

The first issue is one of scale. If you meet in a church hall with about 50 to 100 people with the right kit and the right training you might get away with a self-help approach. Conversely if you meet in a massive cathedral-like space with a vaulted roof, balconies and seating for 1000, then it is time to get help. If you are somewhere in between and you are sufficiently interested to read this far then read on.

Common problems with uneven sound coverage
I have already touched on the issue of sound too loud at the front and too quiet at the back. A normal loudspeaker similar to the one you have in your sitting room is quieter the further you are from it. In fact if you are sitting 6 feet back from it and then move a further 6 feet back the sound level will be a quarter of what it was before. It is obvious that this will be a problem if you are trying to get a constant sound level. The only way you can use this type of speaker in a church is to mount it sufficiently high to make the distance similar for people both at the front and the back. Conversely the speakers used in the 1960s systems didn't work this way. Called ‘line source speakers' they produced a narrow beam of sound with more or less the same level whether you were at the front or the back. The price was that the design made them sound thin and horrible. The installer would use a set of these pointing in appropriate directions to fill all the corners.

Modern so-called PA speakers can have another problem. Manufacturers publish web sites showing a polar diagram which is basically the beam of coverage. Now in reality this beam can look nothing like the published picture. With some speakers (especially the relatively cheap black boxes with a 12 inch grill and a little horn tweeter at the top) then the coverage at vital voice frequencies can look more like the fingers on your hand rather than an even beam. This means that if you are sitting in the auditorium then one person might be able to hear perfectly clearly but the person in the next seat might hear everything sounding muffled.

The modern installer will choose a speaker that will produce a clearly defined audio beam delivering sound where it should be and keeping it away from areas it should not. Unlike the speakers of the 1960s these speakers will sound perfectly natural but still having the power capacity for your music group.

Problems with unclear sound
Sometime the sound in the auditorium is loud enough but is somehow just not clear. The effect is rather similar to poor focus in a photograph. Imagine if you have a photograph of a display board at an exhibition. If the photograph is pin sharp then you can read the text easily. With a slightly blurred photograph you can just about read it, but then you reach a stage when the text is totally illegible. In photography the problem is caused by multiple versions of the same image not lined up with each other. With sound you can get a similar loss of focus caused by the same sound arriving at different times.

This can have several causes: Imagine if there are just two speakers at the front. You will hear the direct sound coming from the speakers but also the sound bouncing off the walls and the ceiling. This effect gets worse the larger the room and the higher the ceiling. Now if you are near the front the sound from the speakers will be much louder than the sound you can hear bouncing off the walls and your brain can make out what is being said even in the presence of low level echoes. However, if you are nearer the back you reach a point where the sound is never clear, irrespective of how loud the volume is set. This is known as the confusion zone.

The common fix is to install another pair of speakers further back. This however doesn't always help that much, especially in a big space. The reason is that someone sitting at the back will be able to hear the speakers at the back first as the preacher says his words but the sound from the front speakers then arrives a little later, leaving the listener at the back having to sort out two loud signals with a time lag between them.

So how does the professional sort this problem out? In a large space he or she will avoid trying to use a single pair of speakers to fill the space but will use lower-powered directional speakers so the person at the back will only hear the speakers near him and not those at the front. The installer will also put in a time delay so that speakers further back will get their feed from the amplifier delayed to compensate for the time it takes for the preacher's unamplified voice and the sound from the front speakers to reach the back. This results in an even sound clear throughout the auditorium.

 

Putting the preacher in his place
One of the disconcerting aspects of using a sound system is that the preacher's voice often sounds disembodied, coming from somewhere in space vaguely adjacent to the nearest loudspeaker. By adding a slight amount of delay to the whole system just sufficient so that you can hear the preacher's natural voice before you hear the loudspeakers, then the brain places the sound at the preacher rather than the nearest loudspeaker and the whole system suddenly sounds natural rather than amplified.

Problems with howl round and ringing
This must be one of the most common problems with church sound systems and can usually be avoided. It is sometimes operational, often caused by leaving music groups open when the preacher is speaking To avoid this training can be a big help, but often the system is just not designed properly. It is a bit like comparing a unicycle and a mountain bike. Most people can ride a mountain bike but a unicycle needs an expert. You want a sound system which most people can operate, not one that is so temperamental that only the experts can operate it. Once again, well-designed speakers will provide a tight cone of sound which will minimise the amplified sound getting back to the microphones. For best results. If the preacher wears a headset microphone, rather like a pair of specs with a short boom, can give outstanding performance. Cheaper versions of these tend to be bulky and can make the preacher look like a submarine commander. The high quality ones can be almost invisible.

( NB: Sometimes howl round can also be caused by the deaf loop being turned up too high.)

Radio microphones (mics)
These can be a blessing when they work well but very irritating if they don't. Many problems are caused by people buying very cheap versions. You would expect to pay around £400 for a decent system. It is tempting to put the receiver at the back beside the sound desk but unless this is on the balcony then you really need the aerials well above head height to avoid interference when the congregation comes in. A better solution is to put the receivers at the front near the mic connection box and feed the output up one of the mic channels. Usually a good radio mic will allow you to alter the mic sensitivity in the radio mic transmitter. It is important to get this right or the sound may be distorted or hissy.
If you are in the process of buying a radio mic then get good advice. To the entire industries horror, Ofcom (The government organisation which controls frequencies) is selling off the frequencies in channel 69 that are commonly used by many radio mics. This change happens after the 2012 Olympics. At the moment there are 10 channels available in band 69 which need a licence and 4 channels in channel 70 which do not. If you use any channel 69 frequencies then this will affect you. Not all radio mics tune to the free channel 70. Any new radio mics will probably be on channel 38. These are not widely available yet. If you are buying now you must make sure that the systems can be retuned to the new frequencies.

Sound desks
These come in a vast variety and choosing one can be confusing. If you have a music band with a lot of mics you want to choose one with multiple groups so you can fade the band in and out on one control. You can also get sound desks with a 'church officer switch'. If an untrained person operates this then it feeds a single mic through the desk without having to worry about all the other settings.

Conclusion
There is no reason why sound in church should be a nightmare. If it i,s then maybe you need to get an expert to sort it out. Seraph Media is in partnership with several highly professional Christian installation companies in the UK .We can also provide advice on projection, video and streaming systems.

If you want sound advice then get in touch.

Stephen Carter

01173500272
stephen@seraphmedia.org.uk