Choosing a Microphone
By Ana Barbu and Cherie Yurco
In his book Recording on a Budget: How to Make Great Audio Recordings Without Breaking the Bank (Oxford University Press, 2010), Brent Edstrom stresses the importance of experimentation when selecting microphones for recording. Although it is possible to give some general tips on microphone selection and placement, the final decision should be left to your ears. Take your time and try different set-ups, experimenting with mike distance and different places in the room. This guide will help you understand a little bit about how different mikes work and offer some tips.
The job of a microphone is to convert fluctuations in sound pressure into electrical signals. The way this is done depends on the type of mike. The two most common types used in home recording are dynamic and condenser. In a dynamic microphone a coil of wire is attached to a diaphragm and surrounded by a magnetic field. Sound pressure waves cause the diaphragm to move and a small electrical signal is produced when the coil moves in proximity to the magnet. Dynamic mikes tend to sound less crisp and transparent, but have a unique color that can be effective. They are often cheaper and more durable than condenser mikes and are often used for amplifiers, vocals, drums, brass, and auxiliary percussion.
Here are some suggestions for miking various instruments:
VOCALS: A large diaphragm cardioid condenser is frequently used, but dynamic mikes can also be effective. Mikes are usually placed fairly close to singers (within 12 inches or so), directly in front of the vocalist's mouth.
ACOUSTIC GUITAR: One or two mikes are typically placed close to the guitar. For example, a cardioid condenser mike could be placed eight to 12 inches from the guitar body (moving further away for more ambient sound) with a second placed halfway up the neck. Alternatively, a matched pair of condenser mikes can be placed in an XY configuration about 18 inches in front, and slightly below, the guitar.
ELECTRIC GUITAR: One technique is to use a dynamic microphone directly in front of the amp's grill. The tone can be changed by using different types of mikes and/or repositioning it.
BASS: Electric bass recording is similar to that of an electric guitar, but recording an acoustic bass is more challenging. For acoustics, try positioning a (small or large diaphragm) condenser mike below the f-holes and angled upwards at the bridge. Alternatively, place a directional mike below the neck joint above the f-holes, aimed at the body of the bass, or use a directional mike near the bottom of the bass, just below the bridge.
PIANO: Because of its size, range, and mechanical noise, a piano can be tricky to mike. Try using two cardioid condensers in a spaced pair above the treble and bass strings.
DRUMS: Drum miking is complex and more than four mikes are often used in recording. For snares and hi-hats, a dynamic microphone or cardioid condenser is often positioned slightly above the snare, with possibly a second mike below the snare and angled upwards. An additional small diaphragm condenser mike, carefully positioned away from the edges, can be used for hi-hats. A dynamic mike is often used on the kick drum. It can be positioned on the front, opposite the beater, or directly inside the drum. For tom-toms, directional mikes can be placed above the heads, near the edge of each drum, or a single mike can be placed between the toms. Small-diaphragm mikes can be used to enhance the brilliance of cymbals. Finally, two overhead mikes are sometimes used to capture the entire drum set along with the ambient room sounds.
SAXOPHONE: A large-diaphragm condenser microphone can be positioned about a foot away and slightly higher than the bell. It should be angled toward or just above the bell. Alternatively, try using a clip-on mike.
BRASS: Different mikes can be used with brass instruments, depending on the effect you want to create. A condenser mike yields a more brilliant tone and dynamic mikes tone down the "brassy" sound. Try positioning the mike to the side of the bell and about 18 inches away.
Condenser mikes, a mainstay of professional recording studios, are usually more sensitive, fragile, and expensive and require phantom power. Small-diaphragm condenser mikes are well-suited to record acoustic instruments (strings, guitar, piano), overhead of drums, or ensembles, while large-diaphragm mikes exhibit more warmth and are often used for vocals, piano, and acoustic bass.
You also need to know your mike's pick-up pattern (how it "hears" sound). Omnidirectional mikes respond to sound from all directions and are great if you want to record the ambience of the room. Bidirectional mikes pick up sound equally from in front and behind the mike. A cardioid mike has a heart-shaped pick-up pattern that picks up signals mainly from the front, and to an extent from the sides, while minimizing signals from behind. Cardioids are useful for isolating one track in multi-track recordings.
TRY THESE
AKG D40 is a dynamic mike designed for drums and percussion, wind instruments, and guitar amps.
(MSRP: $160)
Shure Beta 57A is a dynamic mike for vocals and instruments including brass/saxophone, amps, acoustic guitar, and percussion. (MSRP: $174)
Audio Technica ATM 350 is a clip-on condenser mike ideal for brass, piano, violin, and toms. (MSRP: $489)
Shure PG81 is a sensitive, flat response, cardioid condenser mike, ideal for acoustic instruments such as bass, cymbals, woodwinds, guitar, and piano. (MSRP: $161)
Shure KSM44A is a high-end microphone. This large diaphragm condenser is great for many recording applications, including vocals, acoustic stringed instruments, cymbals, and piano. (MSRP: $1,249)
