Audio Systems for Churches and Synagogues
What Works, What Doesn’t:
I would like to share some of my experience in improving audio systems for churches and synagogues, I will begin by addressing some of the common complaints shared by prospective customers. Note that the vast majority of prospects I meet have already purchased a sound system that is not meeting their expectations.
1. “WHY DO I HAVE TO BE SO CLOSE TO THE MICROPHONE?”
This can be the fault of the microphone because the most popular microphones available today are hand-held dynamic types designed for close-miked rock and roll applications. Witness that the world’s largest selling microphone was originally introduced in 1966 and is shaped like an ice cream cone. Has it occurred to anyone that Ice cream cone shaped microphones are intended to be eaten?
In all fairness, many times the microphone gets blamed and the problem is the sound system itself.
The real problem is a lack of gain before feedback. Gain before feedback or just “gain” describes the ability of a sound reinforcement system to amplify weak sounds. This is ultimately limited by feedback. Feedback occurs when the microphone is turned up high enough to pick up the sound coming out of the speakers. In an ideal world, if you couldn’t hear the talker, you would just keep raising the volume until he could be heard. Anyone who has ever touched a pa system knows if you keep raising the volume it will squeal (feedback).
Well, what about those wonderful black boxes called “feedback controllers” and “feedback destroyers”?
I have found they help a little but not much. Recently I had a customer replace his whole church sound system because a competitor promised that his magical feedback control processor would solve his feedback issues. It didn’t. Instead, he ended up with a very muffled in-a-cave like sound which made speech unnatural and unintelligible. The customer eventually paid me to remove the magical black box and re-install the old equipment.
What then is the answer to the problem of feedback, The mics, the speakers, the mixer, or the equalizer? All of the above, and above that proper sound system design. The directional characteristics of the mics and speakers are of utmost importance. Ideally, the directional patterns of the microphones should not intersect.
Simply stated, the speakers should direct the sound toward the listeners and away from the microphones, and the pickup pattern of the microphones should be oriented so that the microphone is least sensitive in the direction of the speakers. (I am amazed how often a choir director wants omnidirectional microphones so they will pick up everything—and they do pick up everything—including the speakers– virtually guaranteeing feedback!)
Once the speakers and microphones are selected and positioned to accomplish the goal of non-intersecting coverage patterns the rest is easy. Well, easier than the daunting task of choosing the right speakers and putting them in the right place (I’ve spent forty years and I’m still learning).
Every equalizer (when properly adjusted) is a very effective feedback controller. Its filters are adjusted to reduce the “peaks” in the frequency response curve which along with improving the fidelity of the sound, reduces feedback.
The mixer is often overlooked as a source of controlling feedback but it is one of the most effective—if it is connected to a good operator. I spend hours of time training sound system operators and I often point to the “main reason they are here” i.e. to turn off the unused microphones. This drastically improves gain before feedback because every active microphone adds to feedback. The more mics that are active the sooner the system will feedback, therefore, the volume has to be reduced AND THAT’S WHY YOU HAVE TO GET SO CLOSE TO THE MICROPHONE!
If the wide range choir microphones are turned off, the pastor’s head worn microphone or pulpit microphone will work better. Unfortunately, many sound mixer operators must fall asleep or don’t know this or maybe they don’t exist!
This introduces a common problem with audio systems for churches and synagouges—the non-existent sound system operator. Many churches do not have qualified (or willing) people to operate the PA system.
In some Temples and Synagogues, the sound mixer cannot be adjusted on the Sabbath.
And so they have a 16 or 24 channel mixer with its vast array of sound adjustments closed away in a closet with all the microphone channels turned on! And they wonder why people can’t hear!
And they ask: WHY DO WE HAVE TO GET SO CLOSE TO THE MICROPHONE?
Sound Planning uses high-output condenser microphones.
Besides using the best microphones, Sound Planning uses loudspeakers with precise pattern control to avoid having the sound spill over into undesirable areas that will increase reverberation and feedback.
Sound Planning has led the way in the use of auto mixing in audio systems for churches and synagogues and we provide acoustic equalization or “room tuning” with every Church or Synagogue sound system installation.
Is there a solution to the non-existent sound system operator?
I thought you’d never ask.
Enter the automatic microphone mixer. (This is a black box that actually works) It reduces the gain of unused microphones so the microphone in use gets the gain it needs—without feedback.
2. WHY DO THE SAME PEOPLE SAY “IT’S TOO LOUD” AND “I CAN’T HEAR”?
The people that say they can’t hear are really saying that they cannot understand but the audio system operator tries to compensate by raising volume level. This often makes matters worse. (see below)
Also, the too loud complaint usually pertains to the music but the “can’t hear” has to do with speech.
To fully understand this problem, we need to analyze the spectral content of music and speech. Music, especially contemporary music, has most of its energy in the low frequencies (bass). The quality of a sound system is usually judged by its bass output. By contrast, speech and vocal content are allocated more toward the higher frequencies (treble). Even in a deep male voice, the content necessary for intelligibility lies in the treble region (2000-5000hz).
Since the world of audio for churches is driven to a great degree by rock music, more attention is often directed toward producing large amounts of bass both in the manufacture of equipment and its installation. This problem is compounded by the fact that in large rooms, it is much easier to reproduce bass than the higher frequencies which are essential to speech recognition.
Large rooms generally resonate in the lower frequency range while the high-frequency content gets masked. (The vowels actually mask the consonants).
When the board operator turns up the volume the sound excites these room resonances to a greater degree and things get worse.
Things also get worse when you study the characteristics of human hearing as it is affected by the aging process. As we grow older, we lose our ability to hear high frequencies but our ears remain as sensitive to bass as when we were young. Thus the older generation’s lack of tolerance to high-level rock music.
Sound Planning designs audio systems for churches primarily for speech intelligibility.
This in no way compromises musical reproduction. In fact, intelligibility is important in church music as the singers are attempting to communicate a message through this medium.
DO WE NEED ACOUSTICAL TREATMENTS?
Often we are contacted for acoustical wall treatments or acoustic padding or sound absorbers. There is a place for these acoustical improvements in highly reverberant rooms but often acceptable results can be achieved more economically through proper loudspeaker design and installation.
As we have said earlier, directional sound also known as loudspeaker pattern control is critical to achieving optimum sound system performance. It is necessary to direct the sound away from the microphones (to reduce feedback) and toward the listeners. It is also important to direct the sound away from structural components (walls and ceiling) that reflect or resonate sound.
Since the 1930’s, loudspeaker manufacturers have used horns to accomplish this directivity.
Unfortunately, most modern professional loudspeakers utilize horns only for the high-frequency section of the loudspeaker. This yields a design that is highly directional and able to control where the sound goes but only in the high frequencies. Most professional loudspeakers use a direct radiator (essentially a speaker in a box) for the low (bass) frequencies. So what we have is a well controlled high-frequency dispersion pattern, but the low-frequency output is out of control i.e. non-directional—it just spills all over to the ceiling, walls, windows, stage etc. The problem is that most room resonance and reverberation is a low frequency in content. This compounds the reverberant nature of most large rooms and destroys clarity and intelligibility.
For rooms with difficult acoustics, Sound Planning uses loudspeakers with low-frequency pattern control.
There are two practical approaches to obtaining pattern control of the lower frequencies. One is the line array loudspeaker which consists of a vertical stack of speakers configured to narrow vertical dispersion. This technology is also used in outdoor applications to keep sound from “spilling” into adjacent neighborhoods. Indoors, the narrow vertical beamwidth keeps the sound directed to audience level without “spilling” to the higher parts of the room. Since line array speakers are usually large and costly, the second approach achieves similar results with a smaller device and reduced cost.
Electro-Voice has advanced the development of the fully horn loaded loudspeaker. This device incorporates a horn loaded woofer along with the commonly used high-frequency horn. Sound Planning has used these speakers in many highly reverberant churches, synagogues, and gymnasiums with great success. We recently installed one in Ft. Lauderdale in a reverberant church with a 55-foot ceiling and a back wall of glass. A parishioner commented’ “I never knew how bad our old system was until I heard this speaker.”
We sell and install: Long-reach microphones (also known as shotgun microphones), variable pattern microphones, headset and headworn microphones, lavalier microphones, choir boom microphones, flat plate microphones (also known as boundary microphones), wireless handheld microphones, podium microphones, hanging choir microphones, equalizers, compressors, limiters (automatic volume control) analog mixers, digital mixers, digital signal processors (DSP), power amplifiers, subwoofers, crossovers, hearing impaired systems (assisted listening systems).
Brands: Electro-Voice (EV), Telex, JBL, DBX, CAD (Astatic), Shure, QSC Audio, Sennheiser, Bogen, Soundcraft mixers, Protech automakers, Sanyo video projectors, Kramer video processors, Quam ceiling speakers, Vutec video screens.