Any time a band has some of its sound coming through the main PA system (usually vocals and electronic instruments) and some of the sound coming from the stage acoustically (most notably the drums) you have problems.
The drummer must play loud enough to keep up with the sound system, which he cannot hear.
However, playing loudly enough for the back row of listeners means that the drums are often too loud for the first several rows.
It's even louder on stage, which requires the rest of the band to play louder and turn up the stage monitors.
The result is a stage volume that is overwhelming too loud for the room, and often louder than the main sound system in the room, and still unclear.
People get frustrated and irritable, and some leave to find another church where they can understand the music.
A major part of the solution for this problem is to control the sound of the on-stage instruments, beginning with the drums.
There are three steps in controlling drums in church:
1. Contain the acoustic energy from the drums
Containing the acoustic energy from the drums is the easiest part. The sound of the drums travels from the drum head to the ears of the people hearing it.
The strongest part of that sound is generally direct line-of-sight. Many churches have installed plexiglass drum shields around the drums for this purpose. It's cost-effective and it's a reasonably effective starting point.
The plexiglass reflects most sound, preventing the direct line-of-sight sound from reaching the people in the congregation.
2. Absorb the acoustic energy from the drums
The second problem with a plexiglass drum cage is that the first reflection of the sound is concentrated back at the drummer's ears.
The potential for hearing damage is greatly increased. That's one reason some drummers want to play loudly they can't hear the sound as well as they used to, so they feel the need to play louder.
The result of plexiglass by itself is that the total energy of sound is not decreased. Instead, it's just bouncing around the room, making the rest of the sound muddy, and damaging the drummer's hearing.
After we block the direct sound of the drums with a plexiglass drum shield, the next step is to absorb a good portion of the sound, to keep it from filling the room with incoherent echoes. This is generally accomplished with sound-absorptive foam.
Generally, the foam is installed in three locations: on the wall behind the drummer, on the plexiglass itself, and as sound-absorptive "lid" over the top of the drummer.
How much absorption to install is governed by several factors, some practical and some aesthetic. Since the drummer needs to be able to see the rest of the band, it's best to not block all of the plexiglass.
Rather, install foam along the bottom and sides of the plexiglass. Generally, the foam is not installed above the height of the drumheads themselves, and often only to the top of the kick drum. On the sides, install the foam higher, particularly on the side with the snare and hihat, as these are the greatest sources of sound.
Install a greater amount of sound absorption on the wall behind the drummer. In fact, complete coverage of this wall is often appropriate, up to the height of the plexiglass drum shield.
Since the sound from the drums is omnidirectional it will either strike the wall first or it will reflect off of the plexiglass and then strike the wall. Absorption on the wall behind the drummer will be a big help in keeping the reflections around the room under control.
Some of the sound from the drums, of course, goes straight up, where it will bounce off of the ceiling before eventually making its way to peoples' ears.
If you have done an effective job of absorbing the sound inside the drum cage this reduced amount of reflected sound may be acceptable, or even desirable.
It may still be too much sound, especially in a low-ceilinged room, or with a large drum kit, or with a particularly physical drummer. In this case, it may be necessary to add a sound absorptive ceiling over the top of the drum kit.
All this absorption sounds expensive, but it is possible to cover all three sections - on the plexiglass, the wall behind the drummer, and the lid - for about the cost of the plexiglass drum shield itself.
To this point, we have been reducing the overall volume of the drums. The stage volume is under control, so the musicians can hear themselves, and the sound from the stage doesn't overwhelm the main speakers. The front several rows of the congregation are no longer being overwhelmed by sound. But now the back part of the sanctuary isn't being reached.
3. Reinforce the sound that you want from the drums and provide monitoring back to the drummer
The third step of controlling the drum sound is to put the drums into the sound system. At the very least, you'll need to mic the kick drum, the snare drum, and the hihat. With careful placement, a single mic can pick up both the snare and the hihat, for a two-mic minimum.
This solves one problem and introduces a couple of new ones.
Plexiglass does not absorb sound; virtually all of the sound created by the drums is reflected; that means that the sound is still in the room, it's just not traveling to the listeners in a direct route.
The drummer often feels more confident now that he's behind the plexiglass, and often times he plays harder, creating even more sound than before. Now that sound is bouncing around the room as reflected sound.
Reflected sound is, by definition, noise: it has the same amount of energy as direct sound, but because it is reflected, it has become "incoherent." Now instead of hearing the clear "slap" of the snare from a single source, we hear reflections of that slap from various reflective surfaces around the room.
The clarity is decreased, but the energy of the snare is still there, rattling around the room, muddying up the rest of the sound.
As far as mic selection goes, my preference is to use a large diaphragm mic on the kick drum either a dynamic mic like the Shure Beta 52 or the Sennheiser E602II, or a large condenser mic like the CAD E100.
Dynamic mics tend to capture the "boom" of a kick drum well, and condensers can capture the "snap" of the sound.
Audio Technica makes a mic (AE2500) that has both a condenser capsule and a dynamic capsule in it. Be sure that the mic can handle the high sound pressure levels of a kick drum closely miked.
Your first choice for a snare mic is a simple dynamic microphone, with the ubiquitous Shure SM57 being the most popular. It'll take a number of accidental whacks from overly-enthusiastic drumsticks and keep working well.
Dynamic mics can also be used on the toms, but there are several very nice tiny condenser mics that have become popular, like the AKG C418 or the Audio Technica PRO 35.
Sennheiser makes a small dynamic mic for this purpose, the E604. These small, specialized mics generally come with their own mic clips which attach directly to the drum itself, reducing the number of stands and cables sticking out of the drum kit, and allowing the plexiglass drum shield to be brought in nice and tight.
In a large room, you'll want to add a pair of overhead mics, to capture the overhead cymbals and the overall ambience of the drum kit. Small condenser mics like the entry level AT Pro37R or the higher priced Sennheiser E914 are common choices.
Recently, the trend has been moving towards large-diaphragm mics overhead, including the inexpensive CAD GXL2200 or the versatile AKG C3000B. Be sure to experiment with mic placement, listening closely to the sound of each mic, to determine best placement on your drum kit.
Once you route the new mics to your mixing console, you'll need to consider monitoring for the drummer.
The simplest way to give your drummer the ability to hear what he needs to hear is to use an unused Auxiliary Send from your mixing console. Send that aux to a headphone amp (there are many entry-level manufacturers including Samson, Behringer, Rolls, and Carvin).
Headphones with significant isolation help ensure the drummer will get the reinforced sound and not just bleed from around the ear muffs, and some drummers like headphones that emphasize low frequencies. In-Ear Monitor models which produce extended low frequencies (dual driver models) are also an option.
Beyond this simple setup there are many other more advanced monitoring solutions such as a separate monitor console or personal mixing devices from folks like Aviom, Hear Technologies, Furman, and MyMix.
If you have the room, I prefer using a compressor on both the kick drum and the snare, and an ideal world would call for gates on the toms, the snare and the hihat, to tighten up the sound, but most churches will stop before that point.
The main goal is to prevent the acoustic sound of the drums from either overpowering the rest of the band, or reverberating around the room, by bringing the drums into the sound system with the rest of the band. You'll be surprised how much cleaner your band sounds, and how much easier it is to keep the volume under control.