June 2012 Article: Speakers
By: Hugh Sarvis
Here are the big five groups of questions from church leaders when it comes to speakers for houses of worship.
You will use a few more speakers to focus your array and get the vertical coverage you need, but your level (SPL) from front to back, as well as gain before feedback, should be better than a point source system.
Remember the "Inverse Square Law." With every doubling of distance, you will lose 6 dB. In a perfect line array, which really doesn't exist, you will lose 3 dB. In most cases, you will lose around 4 dB, so gaining around 8 to 10 dB over 60-80 ft. is a lot.
If you are hiring a systems integrator, and you should, it would be best if he could offer you a couple of options to best suit your intended application. As an example: Do you have a choir? Do you have a praise and worship team?
Remember your system needs to be able to produce and get a least 15 dB above your ambient room noise, and this measurement should also be calculated at the back of a room. If the integrator is showing you several system designs, he or she should be able to design the system in a software sound system modeling application, such as EASE. This would enable you to see what the SPL and coverage would be like.
3. Center Cluster
First, you always have someone speaking, and it is nice if they can be heard from every seat throughout the room. It is also nice if it sounds like the source is coming from the stage and not somewhere off in space. With performing musicians, the sound guy always prefers stereo sound. However, there is always someone speaking and that signal is always mono.
Because of these considerations, having a center cluster that can cover the room is always good place to start and is normally the least expensive option. If you can afford a LCR (left, center, right) loudspeaker setup, then you can make everyone happy, including the speaker manufacturer.
Putting speakers in the right place is also very important. Years ago, at SynAudCon system training, Don Davis showed us why: Keep your speakers a minimum of 3-5 feet from any reflective surface, this will keep the first reflection down and will cause less problems, so in the design stage of the building process, please allow the system integrator to be involved.
This is very important. Don't wait until you have already broken ground and have your building designed before you hire your system designer.
Hugh Sarvis is chief executive officer or director of engineering for WorxAudio Technologies, Inc., www.worxaudio.com.