Feedback (The Good Kind)
Expert advice for miking instruments

By RaeAnn Slaybaugh

Although miking musical instruments is often a matter of experimentation, Church Business^® asked some experts in the field to get you headed in the right direction. Here's what they had to say, from drums to organs.

Basics: types, pick-up patterns and preventing "spills"

Floyd Paulsen, Roadman Tech Services, Frankton, Ind.: Miking requires both an understanding of the sound source to be miked and the microphone itself. There are two classes of mics: dynamic and condenser. Condenser mics require a power source to work either from a battery or a phantom power supply, but dynamic mics do not. Dynamic mics generally work better on loud instruments, such as drums...or the Space Shuttle takeoff. Condensers work better on softer or distant sources, such as voices or stringed instruments.

Each microphone has a distinct polar pattern. The two most common patterns are omni-directional (picks up sound equally from any direction) and uni-directional (picks up sound on its axis well, but has some rejection either on the sides or back). For live sound, I almost always use a uni-directional mic to isolate one source from another and to help control feedback from monitors.

Bruce Bartlett, Crown International, Inc., Elkhart, Ind.: Leakage, also called "bleed" or "spill," is the overlap of sound from one instrument into another instrument's microphone. For example, if you're miking individual drums and a piano, any drum sound picked up by the piano mic is leakage. To reduce it, mike close with directional microphones; when recording, overdub instruments one at a time on each track of a multi-track recorder; pick up electric instruments with direct boxes or cables; and aim the null of the polar pattern at the undesired sound source. For example, suppose you're miking two adjacent tom-toms with two hypercardioid mics. The null of the hypercardioid is 110 degrees off-axis. Angle each mic so that its null aims at the adjacent tom-tom.

Drum directives

The A-T Snare/Tom mic by Audio-Technica focuses on the desired location without controlling feedback and isolation between sound sources.

Paulsen: Percussion can range from a set of tympani to a whole host of other "toys." Due to its nature, percussion has a tendency to bleed into other stage mics. On louder drums, I usually use a dynamic mic with a large diaphragm to capture the really low tones. For cymbals and metal toys, condenser mics reproduce higher frequency sounds more accurately. With condenser mics, source volume needs to be considered because you can easily overdrive the mic or board input channel and cause distortion. If you have one player on several different instruments, use a wireless lavalier mic. This way, you don't have to tie up lots of channels on the console. The mic follows the player, and with a little instruction and compromise through the sound check, you can balance the distance for a more even level between toys. Another way to mic percussion is to use overhead condenser mics on boom stands to pick up the area of several percussive instruments.

Flute clues

Paulsen: I usually mic a flute from overhead with a condenser mic on a boom stand. When overhead miking, always use a mic stand base of the appropriate size and weight to prevent it from tipping over onto a musician. (Knocking a solo musician out cold with a boom stand can be quite distracting.) Listen for the "sweet spot." If the mic is too close to the instrument, sound is "breathy"; too far away, you lose some of the brightness. The first rule of miking is, the loudest sound source wins! So, the further away from its source a mic is, the greater its chances of picking up sounds from other sources like percussion and electric guitars.

Guitar guidelines

The PRO 7a Miniature Cardioid Condenser Microphone excels in acoustic guitar applications. Special internal construction minimizes handling noise.

Karen Emerson, Audio-Technica, Stow, Ohio: For close-up perspective with minimum feedback, consider a miniature cardioid condenser mic that mounts directly on the guitar with an adjustable clamp adapter. Another approach is to use a wide-response cardioid condenser mic on a stand or short boom with the mic pointing at the bridge of the guitar. If ultra-close miking is needed, avoid placing the mic too close to, or directly facing, the sound hole to avoid a "tubby" sound.

Tim Vear, Shure Brothers, Evanston, Ill.: The acoustic guitar is a relatively small sound source that can usually be picked up well by only one microphone since most of the sound comes from the sound hole and the top of the guitar. A mic positioned in front of the guitar can get an excellent overall sound, but it will vary depending on its distance from the sound hole and its orientation to the top of the guitar. Generally, sound will be louder and "bassier" closer to the sound hole, softer and "thinner" farther away. Position a full-size microphone on a stand to give the desired sound. You can also mount a miniature mic directly on top of or inside the guitar with a clip or holder, which keeps it at a constant distance and allows the performer freedom of movement, especially when used with a wireless transmitter.

Paulsen: Guitar musicians usually have a certain sound they want to capture. Some acoustic guitarists want a classical sound that is very dull, not bright, so that you can't hear the fingers slide on the strings. Others want a bright sound. For acoustic guitars, I use a very tight uni-directional mic. Condenser or dynamic? The choice is yours. If your stage monitors point at the face of the guitar, I would choose the dynamic. The face of the guitar can cause feedback. I have also found if I don't point the mic directly at the hole on the body of the guitar, I don't have as many problems with low frequency feedback. I like to point the mic between the hole and the neck of the guitar. That way, I have more EQ flexibility.

There are guitar pick-ups too, which work fine, but not every player likes the sound the pick-ups offer. For electric guitars, use a direct box (electronic interface) or a mic. Most guitar players don't like direct boxes because they like the sound of their own speaker cabinet. I usually use a dynamic mic either draped over the face of the speaker or on a boom stand.

Harp how-tos

Dynamic mics generally work better on loud instruments, such as drums...or the Space Shuttle takeoff. Condensers work better on softer or distant sources, such as voices or stringed instruments.

Paulsen: As with any stringed instrument, harp sound is generated while vibrating a surface--in this case, wood. A condenser mic placed in foam (to shock mount the mic) in the second or third hole from the bottom works well. Playing a harp is a foot-physical task, so make sure the mic cord doesn't get in the way. As always, discretely listen for the sweet spot. A jazz harpist I once toured with moved the whole instrument around onstage, so we used a wireless lavalier. A support brace is located inside the sounding board of the harp, but be extremely careful when mounting the mic clip not to scratch the wood. I use a good quality stage gaffe tape to cover the teeth on the clip for protection. The mic might slide off the instrument, but chances of scratching the wood are slim.

Whatever I'm miking, I try to duplicate the sound coming out of the speakers with the sound coming from the source. Listening to the source up close and personal goes a long way.

Piano pointers

Vear: As a large acoustic source, a piano's sound comes from the soundboard, strings and reflections from the lid and other body parts. Due to gain-before-feedback limitations, it is not feasible to use a distant microphone, so placing the microphone close to or inside the piano is the normal procedure (e.g.,, using a full-size microphone positioned close to or inside of the piano--with lid open--using a stand and boom). Over the treble, a microphone yields a bright sound. A middle position--over the low strings--corresponds to a sound with more bass. Placed near the hammers, a mic picks up a sharper sound. As it is placed further away, sound is heard softer.

To reduce feedback and isolate sound, a boundary mic is sometimes attached to the underside of the partially or completely closed lid. When dealing with a large source like a piano, close mic placement may not pick up the full sound, so two or more mics can be preferable, especially for stereo reproduction.

For close-up stereo miking, two mics can be centered about midway between the low and high strings six to eight inches above the strings.

Emerson: The piano is one of the most demanding instruments to record or reinforce accurately. The mic selected should have a flat, extended frequency response and excellent transient response. While a grand piano is designed to be heard from a few feet or more away, isolating the piano requires getting close.

One alternative is to mount one boundary (plate) mic, or two for stereo, inside the piano, either permanently attached to the lid's underside or on temporary "bridges" of duct tape affixed to the metal ribs over the strings (insert figure 12d, p. 16-flagged with post-it as Graphic #2). These boundary mic techniques are often good choices when the piano lid must be closed, and they offer control over leakage of other sound sources into the piano mic when recording.

Because the upright piano is a large instrument, two mics spaced between six and 18 inches behind the soundboard are recommended. They should be far enough apart that one picks up sound from the high strings while the other picks up the low notes. In stereo recording, the two mic outputs should be "panned" slightly left and right at the console. For greater isolation of the piano sound, remove the lower front cover (below the keyboard) and position a single mic facing slightly upward, away from the pedals and somewhat nearer the high strings.

Paulsen: To mic a piano, have someone play and then you listen for the sweet spot inside. If you have a talented piano player, two mics are the norm--I use a condenser for the high strings and a dynamic for the low strings. With the lid up, you can use boom stands, but when the lid has to be down, several approaches work. I have taped a Pressure Zone Microphone (PZM) to the lid, but the downside, of course, is that the tape will occasionally come loose during a concert. You can also screw this mic to the lid, but I recommend using the tape approach first. Be absolutely sure you like the spot to which it is mounted...and that you own the piano!

I have also used a mic on a piece of foam (shock mounting) next to one of the sounding holes with the lid closed, so figure out which hole has the most even blend of high and low strings. I have even used a wireless lavalier in a piano when miking for a talent show with about 23 different locations for the artists and their accompanists. In that case, the wireless was the winner.

Organ optimizers

Vear: In many churches, the organ might be the largest sound source of all, but few are reinforced by sound systems. Since the organ also possesses the largest range, proper mic placement is important. Since it is not possible to use individual mics on the many pipes or loudspeakers, coverage must be employed.

If the goal is to reproduce sound as heard by a worshipper, position one or two mics (for stereo) in the body of the church, over the congregation, and aimed toward the main organ ranks for a representative organ sound with a high proportion of "room" (or ambient) sound. If a room's acoustics are favorable, and if the level of the organ is balanced with both the choir and sound system, this is the simplest way to simulate being "in" the church.

If the idea is to reproduce a "concert" organ performance, place mics close enough to each of the main locations of pipes or tone cabinets that they "hear" primarily the local organ sound, not ambient sound, to control the level of the organ independently of the choir and other sounds. It may be possible to mount mics on stands in organ galleries as well as overhead in front of exposed ranks.

For more on microphone selection and placement, visit www.sundaysoundman.com, www.audio-technica.com,  www.shure.com, or www.crownaudio.com.