There's more than one way to select and place microphones. After having reviewed the science of microphones, bear in mind that recording is an art. The placement of your microphones determines what your listener will hear. There are some established conventions that achieve certain results. We'll look first at the basic underlying techniques, then move on to some specific examples.
Just do it: Sometimes the best way to learn about mic placement is simply to try it. Set up a microphone near a source and begin monitoring the results. Be sure to experiment with distance and angle.
Any recorded sound comprises both direct and indirect or reflected sound. Direct sound travels straight from the source to the microphone and is the "cleanest" sound because it is unchanged from its source. Indirect sound reflects off surfaces in the room or recording environment before reaching the microphone; it is colored in the process and arrives with a small delay.
By using different mic placements, you can affect the mix of direct and indirect sound. The most basic forms of microphone placement are close and distant (or ambient ):
Close miking is the use of microphones near the source, as in a vocalist singing directly into a microphone or the placement of a mic directly next to a guitar amp or kick drum. Close miking picks up mostly the direct sound.
Distant (ambient) miking is the use of greater space between a mic and source, such as a boundary mic onstage or a stereo mic in the audience of an orchestral performance, and tends to pick up more reflected sound.
The blend of direct and reflected sound you want to record depends on the result you're trying to achieve. If you want an intimate guitar recording, one that might sound as though your ear were up against the body of the instrument, you'll want as little reflected sound as possible. On the other hand, if you're recording a choir performance in a cathedral , you'll want to capture some reflected sound since this is a desirable quality of the space.
Either way, excessive reflected sound can cause problems. Phase cancellation occurs when certain partials arrive 180 degrees out-of-phase with respect to the direct sound. Phase cancellation causes some frequencies to disappear, thus creating a hollow sound. One way to compensate for this problem is to use boundary mics for distant miking (see the sidebar "Boundary Condenser (PZM)"). Too much reflected sound can also make a recording sound muddy. Solutions include employing more direct miking or setting up acoustic barriers to prevent reflected sound from reaching the mic.
To obtain the desired mix, many recordists use some combination of close mics and distant mics. Even with only two microphones, this combination will give you options when blending the two signals.
Pros and Cons
Stereo microphones: You can purchase a single stereo microphone that contains two diaphragms (one for each side), with separate left and right connections. Shown here is a cutaway of the Neumann USM 69 stereo condenser, showing the positioning of its two transducers . (Photo courtesy Georg Neumann GmbH)
Advantage: Added convenience of using only one mic.
Disadvantage: Limited control over the stereo image.
Spaced (A/B): When two microphones are mounted some distance apart, natural delay will create a stereo image. You'll want to use similar or ( ideally ) matched cardioid or omni microphones. There are a variety of approaches to A/B miking, ranging from using angled mics inches apart to using mics several feet apart and parallel.
Advantage: Good wide-range stereo field.
Disadvantage: Mixing to mono is problematic as phase cancellation can result. Too large a space can be unconvincing in some cases.
X/Y pair: Mounting two similar or matched cardioid or bidirectional microphones at 90110 ° angles allows an overlapping stereo field with no phase problems. (Bidirectional mics will include sound captured from the rear, as well, blending it with the front.)
Advantage: Reliable sound with no phase cancellation. Bidirectional X/Y pair adds ambience.
Disadvantage: Creates a less convincing stereo image of a large ensemble.
Middle/Side (M/S): This system combines a cardioid or omni mic with a bidirectional mic. The cardioid mic picks up sound directly forward, and the bidirectional mic fills in the sides. This system requires an M/S decoder to separate the middle and side to right and left, either via hardware or a software plug-in ( Figure 6.11 ).
Advantage: No phase cancellation and full control over mix of direct (mid) and indirect sound (side).
Disadvantage: Requires M/S decoder.
With a stereo microphone, or an A/B or X/Y pair, mixing stereo signals is easy: one mono channel is left (so you'll pan it all the way to the left when mixing), and one is right (so you'll pan it right). With M/S miking, you'll mix directly in the decoder or, after decoding, use the left and right channels as you normally would.
For a full recording of an ensemble, you'll use a combination of mic strategies:
When in doubt, go stereo: When miking ensembles, you'll at least want a basic stereo configuration (X/Y, A/B, M/S, or spaced). This is especially common when recording classical music ensembles . Then, gradually add accent mics or "spot mics" and other individual mics to get the mix you want.
Overall pickup: A mono microphone (or stereo pair) that picks up the general sound of the space and sourceboth direct sound and ambience.
Ambient mic: A mic designed just to pick up the recording environment more than the source, such as the ambience of the room or audience noise (surround-sound live recordings, for instance, will often mic the audience for the rear channel).
Instrument mics: Mics that are intended to focus on direct sound, for either miking each individual instrument or using additional accent mics to add a little bit of focus to the overall pickup.
You'll then match your mic pattern and characteristics to the instrument (or other source) and sound you want to capture.
An infinite number of potential sound sources and ways to mike them are available, but the best way to begin is to consider the following factors:
Hold the EQ: It's better to get the tonal quality you want with your choice and placement of your microphone than to try to change the tone later in the signal path using equalization. You can always add EQ during the mixing process, at which point you'll have more creative choices if your original recording sounds good. See Chapter 7 for more on equalization and other effects.
What sound does your source produce? Determine your source's amplitude and frequency characteristics.
How (and where) does it produce that sound? Mic placement should exploit where particular sounds are best heard on the instrument or source.
What sound do you want? Do you want to capture the full frequency and amplitude range of the instrument, or will some rejection of low- or high-frequency sound "warm" the recording or eliminate unwanted sound components ?
With these issues in mind, we'll look at conventional means of miking the instruments you're likely to record most often.
Vocals are fairly straightforward to record because there's only one sound source and you already know where it is: the vocalist's mouth. In this situation, you'll face just a few challenges:
Number of mics: 1
Best pattern: Cardioid (omni distant miking for large ensembles)
Best placement: Close miking (a few inches to just over a foot )
Tips: A dynamic mic is best for rugged applications; condenser/ribbon mics are best for the spoken word. Use a pop filter if you can.
Make sure your vocalist (and you) use good mic technique: hold the mic steady if it's handheld, or even better, use a stand. Don't touch the grille of the mic head.
Generally , keep the mic 34" from the vocalist's mouth ( Figure 6.12 ). You might want to move it a few inches farther away depending on the vocalist's singing style or if you desire more indirect sound. Move the mic slightly closer if you want to intentionally utilize proximity effect to thicken or deepen the sound.
Cheap pop filters: The material in commercial pop filters is similar to ordinary nylon panty hose, so intrepid DIY types have built their own, using an embroidery hoop as a frame. Christopher Stark has instructions online at www.kaiaudio.com/projects/xplosive.html. Other solutions include placing socks over the microphone head.
You'll need to deal with plosives and sibilance , the blasts of air produced by normal speech, and excessive sibilance, which consists of high-frequency s, sh, f , and other similar consonants. A pop filter, also known as a pop shield ( Figure 6.13 ), is cheap and will help overcome plosives, while for sibilancethe hissing sound produced by consonants like the letter "s"you may want to have the vocalist point their mouth slightly to the side of the mic.
If you have more than one singer, either give each singer a mic or, if that's not possible, choose a mic with a wider pickup pattern. Onstage, omni isn't ideal, but a wide cardioid pattern will still be effective.
The key to recording acoustic pianos is to pick up both high and low strings while deemphasizing the distracting sounds of action and pedals.
Number of mics: 2 or more
Best pattern: Omni
Best placement: Close-miking soundboard or stereo pair pointed at the lid
Tips: Thanks to the lid of a grand piano, it's possible to use a boundary mic. Regardless, you'll want to keep the piano lid open (half- or full-stick).
Condenser mics are preferred; one of the mics could be a boundary mic taped to a grand piano's lid. Of all the instruments, the piano's full-frequency range is especially well suited to a high-end condenser, particularly for solo music.
Because the piano's rich sound is a result of internal reverberation and sympathetic resonance of stings, you don't want to place your mics too close to the strings. Leave at least 6 inches so your recording balances sound from individual strings with the sound of the soundboard. Ideally, you'll want two mics, so as to cover both the bass and treble strings (if you have an upright piano, simply open the top).
The sound of a piano varies at different parts of the instrument: hammers have a more percussive sound, whereas the soundboard tends to be richer and fuller . To get the sound you want, you can change the positions of your two microphones, or use even more mics (especially if you're working with a longer concert grand). If you only have one mic, don't fret: choose an omni pattern and position for the sound you want. The sound is richest over the strings, most percussive at the hammers, and thinner at the sound holes, and you can emphasize treble or bass by relative position over the corresponding strings.
Grand tour of the grand: A grand piano gives you more physical space to explore than any other instrument. So try experimenting with different parts of the inside of the soundboard and various distances from the instrument to get the sound you want.
You can hook up an electric guitar directly into your direct box ("DI" box) or interface, but if you have an amp you love and want to capture the way it colors your sound, you'll need to mic the amp ( Figure 6.15 ). The traditional way of doing this is to point a dynamic mic at the screen of the amp, even positioning it close enough to touch the surface of the amp. (Don't try this with your expensive condenser mic!) The result is a very thick, aggressive sound. You'll typically get the best results with the amp turned up and the mic at an angle to the amp, pointed indirectly at the cone.
Number of mics: 12
Best pattern: Cardioid
Best placement: Close miking the amp or a combination of close miking and ambient miking
Tips: The "American" (versus "British") sound tends to employ condenser mics over dynamic mics, but be sure to give your condenser some distance so it isn't damaged!
If this setup doesn't give you exactly the sound you want, you may want to add a second mic (more often a condenser), either for distant miking or pointed at the back of an open- backed amp cabinet. This second mic can be used to add some subtle additional sound or to make it clear that your garage band is playing in a real garage!
The other option is to make the amp entirely virtual, either by using a hardware amp simulator from a vendor like Line 6 (www.line6.com) or using a software solution, like IK Multimedia AmpliTube, Native Instruments Guitar Rig, or Guitar Amp Pro in Apple Logic Pro ( Figure 6.16 ). These software packages emulate the miking techniques described in this section, so even if you're going virtual, it's helpful to have knowledge of guitar miking.
Bass tips: Bass is often recorded directly for a cleaner sound, but you can mic a bass amp just like a guitar amp. Large-diaphragm condensers are especially useful for picking up bass sounds. IK Multimedia also makes software models of Ampeg bass amps (www.amplitube.com).
Acoustic guitar has a full frequency range, making it an ideal test for a high-quality , large-diaphragm condenser. Steel-strung guitars are generally close miked from the soundhole (slightly off-axis), whereas the more delicate sound of a classical nylon guitar is better served by miking the bridge.
Recording acoustic guitar:
Number of mics: 12
Best pattern: Cardioid
Best placement: Close-miking amp or a combination of close miking and ambient miking
Because of the range of sounds from the fretboard, bridge, and soundhole, acoustics are well suited to a two-mic setup as well. Possibilities include:
X/Y pair (see p. 172) centered on the soundhole
One mic on the fretboard, one on the bridge
One mic on or closer to the soundhole, one on the bridge
Rules are meant to be broken: Condensers are usually favored for acoustic guitars, but if you want edgier guitar to emphasize finger-plucking or rhythmic playing, substitute a dynamic mic.
With two mics, you can experiment with different setups for the exact balance desired in stereo.
Miking drums is perhaps the most idiosyncratic of recording techniques, but a basic setup involves individual mics for kick, snare , and hi-hat, with overhead condensers for toms and cymbals. If you want a grungy "garage" sound, you could mic the whole kit via one distance mic, but for more clarity, consider bringing out some individual elements of the kit.
Number of mics: From two to many; varies (average around 56)
Best pattern: Cardioid/supercardioid
Best placement: Distant miking is possible, although close miking is more popular with multiple mics
Tips: Substitute supercardioid instead of cardioid if you want a tighter, cleaner sound with less spillage. Boundary mics work well on bass and snare, and even good budget models are often effective.
There are some conventions for how to best mic individual drums. Using Paul Wertico's studio setup ( Figure 6.18 ) as an example, we'll look at these one at a time. Paul is a Shure artist, but even if you're using another brand, the same basic principles apply.
Overheads: Overhead condensers (cardioid) in a spaced pair or X/Y pair will pick up a balance of cymbals and the overall sound of the kit. Paul uses two Shure KSM32 condensers.
Hi-hat: A condenser mic (cardioid) can be pointed at the hat slightly off-axis. (Some like to double up miking the hi-hat and snare via a mic placed between thema bidirectional pattern can work well.) Paul uses one Shure SM81 condenser.
Toms: For individual miking, dynamic mics (cardioid) can be used above the head, either for each tom or in pairs. Alternatively, use overhead condensers (cardioid) to pick up the toms with the cymbals. Paul uses three Shure A98SPM miniature condensers.
Snare: A dynamic mic (cardioid/supercardioid) can be angled at the inside top rim, close to the surface of the snare (1"), pointed away from parts of the kit that could leak. Paul uses one Shure SM57 dynamic.
Bass ("kick"): A dynamic mic (cardioid/supercardioid) or specialized condenser can be pointed at the head (adjust distance to your preference). Large-diaphragm mics like the Shure Beta 52A often work well, although a smaller diaphragm inside the kick is also effective. Consider using a pillow or blanket inside the drum; the damping effect will keep your kick sounding sharp instead of muddy. You can even lay a dynamic mic directly on the pillow or blanket. Paul uses either one Beta 52A (specialized kick dynamic) or one Shure SM91 (specialized kick condenser).
Distance mic: For additional ambient sound, a condenser mic (cardioid) can be used at a distance of a few feet from the kit, although the above setup should cover the sound of the kit itself. Paul uses two KSM32s (not pictured), which he also uses as " floaters " for additional percussion and general-purpose recording tasks .
It's the drums: Drum miking is as much about drums as microphonesif not more so. Drum damping and tuning will radically affect the sound of the kit and with it your recording, so if you're not getting the sound you want, adjust the drums.
If you are short on microphones, make sure you have at least one overhead mic (ideally about a foot from the top of the drummer 's head), and then focus on bringing out other focused sounds, like the bass and snare. (If you're sampling individual parts, of course, you can just record one drum at a time.)
Most brass instruments can be miked individually, pointing a mic at the bell (the opening of the instrument). To better tolerate the blast of wind these instruments produce, the instrument should be placed off-axis (or the player should play off-axis from the mic), particularly at close distance.
Best mics: "Instrument dynamic mics" and ribbon mics are preferred for brass.
Tips: Pros use diffusion walls behind brass ensembles to get a diffused sound of the whole group , with a stereo pair as the pickup.
Trumpet and trombone are often close miked ( Figure 6.19 ). Consider a windscreen to further protect the mic from wind blasts.
On-axis with bell
Off-axis placement for mic
Tuba and French horn are usually miked from a few feet away. With the horn, it's customary to focus on capturing more reflected sound, placing the instrument near a reflective wall.
For ensemble recordings, use a combination of relatively close mics (high enough off the ground and far enough back to capture the whole section) and ambient mics.
In contrast to brass instruments, woodwinds radiate sound from the length of the instrument; different sounds can be captured in various positions. Most woodwinds are close miked at a distance of a few inches to a foot. The best positions for recording each instrument are generally:
Best mics: Large-diaphragm condenser, mini-condenser, specialized pickups
Tip: Focus on lower fingerholes in placement.
Clarinet: Lower fingerholes ( Figure 6.20 )
Saxophone: Middle of the instrument, angled slightly toward the bell, to pick up sound from both locations. (Adjust the position to your preferenceaim at the bell, use a pickup on the bell for the brightest tone, or point slightly away from the bell for a fuller tone; see Figure 6.20 .) Ribbon mics are popular for sax recordings as well, with the addition of tube mics for warmer recordings of genres like Latin and jazz.
Back off: Distance is essential to getting good woodwind recordings. Get too close and you'll have too much reed/mouthpiece sound; a few inches (or even feet) of distance can help balance out the sound.
Flute: Roughly in the middle of the instrument: closer or further away from the mouthpiece for more or less breathiness.
Bassoon: Lower fingerholes, often lower than the other instruments, or even recorded slightly to the side of the mic.
String instruments radiate sound from the f-holesthe curved holes on the face of the instrument. To pick up the sound resonating in the instrument blended with the sound of the bow, position a cardioid microphone on-axis with the instrument. The mic can be positioned anywhere from a few inches from the instrument (which will create a sharper, more cutting sound) to 2'3'. Because of the wide frequency range of a resonating string instrument, this is another case that calls for a high-quality condenser mic, especially for solo recording.
Best mics: Large-diaphragm condenser, mini-condenser, specialized pickups
Tip: Focus on f-holes for placement.
Engineer with a baton: If you're recording large ensembles, you may rely on a conductor or group leader even more than your mics: they're essential to providing the balance you need for the recording.
Don't throw away that cheap mic: Inexpensive portable electret condenser stereo mics, like those manufactured by Sony to complement MiniDisc recorders or those built into a recorder like the Edirol R-1, can get surprisingly good soundand they fit in your jacket pocket.
What about other types of recordings, such as "found sound" on-site recordings, special effects, and Foley sound-effect recordings for video? Large-diaphragm condensers or stereo condensers (the latter are especially useful for on-location work) are useful for general-purpose sampling because of their broad, flat frequency response. In general, think about the source. You may find similarities to the instrumental categories mentioned earlier.