basic thoughts to church-pa

PA in Churches

Some basic thoughts on history and function

Gunter Hauser - the author of this article - is a minister in the Protestant Church of Baden, in south-west Germany. He is a musician (Spirit'n'Jazz, Douglas & Hauser, tutto vanitá) as well as a sound technician and producer of several CDs, and he is an advisor in PA installations.

Paul Douglas is currently working as a piano, keyboard and brass teacher, as well as a freelance musician. He has over 20 years experience of leading worship, music seminars, and performing in various churches, theatres, concert halls, schools and open-air venues in the UK, USA and Europe, including many alongside Gunter.

PA in Churches

Most Churches have some type of speech reinforcement. Our church tradition has virtually defined this type of PA. The framework for the conception of these installations has been a service programme dominated by:

· Speech from a lectern and/or pulpit

· Music from an organ

· Music from choirs

This means that music was marked by rhythmically smooth sounds with focus on melody and harmony. In acoustics with loads of reverb and reflections this sounds even more interesting and doesn't really need any PA at all.

Big cathedrals often have long reverberation times of seven seconds or more. In such venues, the necessity of speech-pa, which gives the audience the possibility to easily understand the preacher, was born. In this constellation PA gets its sole task of delivering the speech contributions understandably to all visitors. No more or less. Additionally the PA should not be seen or at least should be as unobtrusive as possible.

The answer to this task has been the systems with many narrow groups of de-centred and dispersed installed speakers. These systems are working with low levels out of many small speakers, which have no delay-line connected and are working simultaneously. They are developed to deliver speech in large and acoustically very difficult churches. Therefore problems occur in the following areas:

1. Delay and Reflection

Sound reinforcement with de-centred speakers is only possible at low levels, before getting too many problems. From medium levels and above, (e.g. reading simultaneous to the organ, or singing with a music group) the dispersed position of the speakers will be a major problem.

You can hear delay-effects caused by different running times, which lead to additional and artificial echoes in the room. Sound (airspeed of c.340 m/s) takes around 100 milliseconds (0.1s) to travel a length of 30m. So if you have 10 speakers in your church in different places, the sound out of these comes to the listener at ten different times, unless they are positioned in a circle around one listener in the centre.

Normally, each member of the congregation has one speaker close to them and they hear the sound from the other speakers as lower additional delay effects. This means, such an installation makes the often difficult acoustics of a church even more complicated by adding even more reflection type delays. A delay line for the different speaker groups would be a better solution, so speakers further away from the sound source would sound accordingly later.

2. Lower Frequency

In the frequency spectrum small speakers cut the frequencies lower than 250 Hz, often 500 Hz. With this effect you often solve the problem of having low frequency reflections in a big room. However, you also take in the disadvantage that the delivered sound often gives a telephone character to voices and everything sounds thin and shallow. Delivering music with such a frequency response is nearly impossible. Therefore, these speakers are not capable of delivering music at even medium level of loudness.

3. Direction & Audio Positioning

Another problem of the decentred position of speakers is the artificial effect, that sound comes from a totally unexpected direction in comparison to the optical view of the preacher, singer or musician. In the current context of entertainment culture with complex and accurate 'surround-sound', this is awkward to the ear.

The function of a church PA system has already changed and is still altering:

a. Service programming is getting more complex. Often there is contemporary music (both live and recorded) using rhythm and a big frequency spectrum with plenty of low frequency required. Also, most styles need a sound reinforcement for each instrument. Here the different instruments are balanced to each other.

b. Church environments are mostly smaller (especially in terms of cubic volume) and not as acoustically difficult as the big cathedrals. Under these conditions congregations with smaller churches start to discover the qualities of Music PA systems, which are sometimes brought along by bands. Suddenly the voice of the minister sounds warm, close and intimate for prayers. And the acoustics of the church are often dry enough, to take a centred PA position from the front without any problems.

Conclusion: The PA conceived for the big cathedral is not the right system for other churches, because the acoustics are completely different.

Facing this, some ministers and church leaders start to wonder: what if the music-PA from the band didn't look like a Disco and was smaller and easier to handle? … the sound of it could do well enough in church…

To this task there are new answers:

I. The traditional Speech PA systems can now be supplemented by a subwoofer, to produce a wider spread of frequency, producing a rounder, fuller sound. This adds low frequency signals and lets the voice sound more natural. But there are still the major problems of artificial delays and the inability of producing higher sound-levels. And, in addition, there is still the strange effect that sound comes out of an unexpected direction.

II. Music PA systems, meanwhile, are offering smaller speakers with unobtrusive designs but still have powerful sound capabilities.

a. Acoustic benefits, in comparison to the speech PA are:

· a wider frequency spectrum in the low frequency range

· connected to this comes a more natural sound character

· the possibility to reach medium and higher levels of sound (Solo vocalist or flute with a music group is suddenly possibly, also scripture reading with the organ)

· full compatibility with all styles of music

b. Economical benefits are:

· Lower price range because of higher production-numbers of the units produced

· By using and combining different components you can get the optimum combination to fit your special church environment.

· Music PA systems have a big number of companies operating in comparison to the market for specialist Speech and Church PA systems

In practical tests you will find that a centred installation from the front gives a significantly better and more versatile sound and is the more economical solution.

Dispersed and de-centred systems can still be needed for bigger churches with very difficult acoustics, but then should be installed with an appropriate delay line. In addition, speakers should be set to deliver the full frequency spectrum equally, (including at higher levels) for a natural sound.

However, we still are left with the often-discussed optical integration of the speakers into the church environment. Here you will also find new solutions:

· Powerful and capable speakers are getting more and more compact.

· Using suitable colours you can get a harmonic visual integration in to your room.

· With a centred installation at the front you don't need to hide several speakers throughout the church, there often being only two units left and right on the front wall.

· Sometimes you can even integrate the speakers into your walls or get them designed according to your church architecture.