Making an Independent Recording, Part 2

Part II – Microphone Techniques

The following article is an excerpt from Shure Notes, Issue #14 (October 2005).

With the possible exception of the music you play and how well it is played, almost nothing has a greater effect on sound of recording than microphone technique. Which mic you choose — and where you put it — affects the recorded tone balance and the desired amount of room acoustics.

In this issue, we’ll give you some of the most usual ways to place mics for recording. But remember, mic technique is largely a matter of personal taste – what sounds right for players, instruments and the song is right. There are no absolutes here – just helpful guidelines.

We’ll start with the most basic procedures, review mic characteristics, then offer specific configurations for the instruments and applications you’re most likely to face in recording your music.

The Most Basic Basics

  1. Choose a microphone with the right frequency response for the instrument or voice you’re recording.

    Every microphone has a specific frequency response. The Shure KSM137, for instance, is a good choice for keyboard instruments.

  2. Place the microphone at various distances and positions until you get the sound you want. If you don’t like it:
    • Change the microphone
    • Change the position
    • Isolate the instrument
    • Change the sound of the instrument (for instance, replacing worn out strings on a guitar)
  3. Eliminate poor room acoustics and unwanted sounds by placing the microphone as close as possible to the loudest part of the instrument to isolate the sound better.

Choose the Right Tool for the Job

Start with the Microphone
Studio recording is different from the world of live performance, but mic characteristics are the same. In the studio, you want the control and freedom to isolate certain instruments – and since there aren’t live loudspeakers to contend with, feedback isn’t an issue. There are basically three considerations in choosing a mic for recording (or any other purpose) – operating principle (or transducer type), frequency response and directionality (also called polar or pickup pattern). Here’s a quick review.

  1. Operating Principle
    Inside the microphone are transducers – mechanisms that turn sound waves into electrical energy. It’s important to understand the nuances between the two most common types because they handle and capture sound differently.

    Dynamic
    A simple, rugged diaphragm/coil which sits inside a magnetic field. It handles extreme volume levels without distortion.

    Condenser
    A lightweight, sensitive diaphragm that precisely and smoothly captures sound nuances. It requires an external power source, either phantom power or battery (on some models).

  2. Frequency Response
    Every microphone has a signature and part of that signature is its Frequency Response. Frequency response determines the basic “sound” of the microphone. It is determined by the range of the sound (from lowest to highest frequency) that a microphone can reproduce and how that sound varies at different frequencies.

    The most common response curves you are likely to see are flat and tailored. When you look through catalogs or web pages, you’re probably going to see icons that look something like these.

  3. Directionality. There are two basic types – omnidirectional and unidirectional.

    This is the symbol associated with an omnidirectional mic. It is sensitive to sounds from all directions.
    Best to use when more room ambience is the goal. Direct and ambient sound can be adjusted by moving the mic closer to or further from the sound source.

    This is the symbol most often associated with unidirectional microphones. These are sensitive to sound coming from only one direction – let’s say from a guitar amplifier. The most common type of unidirectional microphone is called a “cardioid” because its pickup pattern is heart-shaped. It picks up most sound from the front of the microphone and some from the sides.

    Supercardioid or hypercardioid microphones offer even greater sound isolation through narrower pickup patterns.

In the next section, we’ll offer some tried and true mic placement suggestions, along with recommended Shure mics. In many cases, a wide spectrum of mics is appropriate for the instrument. In an attempt to keep things simple, we’ll give you economy (PG mics, for instance) through recording excellence (KSM) suggestions.

Note: For a thorough understanding of the general topic of mic techniques, we suggest Shure’s education booklet, Mic Techniques for Recording. There you will also find a complete Shure Microphone Selection Guide.

Starting Points: Mic Placement for Vocal and Instrument Recording

Single Vocalist

When recording a single vocalist, you’ll probably want to capture the voice only. In larger studios, singers are almost always recorded in isolation booths using cardioid condenser mics.

In a project studio, though, you can achieve some degree of isolation by surrounding the vocalist with baffles or gobos to reduce the reflected sound from the room.

For singers more accustomed to floor monitors (and less comfortable with that sense of isolation) another technique is to use a supercardioid mic, with the null aimed between the studio monitors. The singer can hear a mix of the music and voice – and the polar pattern of the mic will reject sound coming from the monitors.

Group Vocals

We’re going to assume that you are not going to be recording a choir or a large ensemble. (If you are, please go to our discussion of Choir Miking Techniques in a previous Shure Notes for Houses of Worship issue)

Here are two simple techniques you might try:

  • Omni Solution: Have the group of singers circle around one onmidirectional mic.
  • Uni Solution: Position the singers the same way, but have them cluster around two back-to-back cardioid mics.

With a little practice, you may be able to capture the natural and pleasing blended sounds of their voices.

Electric Guitar

The electric guitar has sound characteristics, believe it or not, similar to the human voice. A shaped response microphone designed for voice works well.

Acoustic Guitar

When recording an acoustic guitar – or any acoustic instrument – try placing one mic three to six inches away from the sound hole and another mic of the same type four feet away. You’ll hear the instrument and the room ambiance. Record both tracks dry and flat (no EQ), each to it’s own track. They’ll sound vastly different – combining them in the mix will give you a distinctly open sound.

You can try this technique on any acoustic instrument. Listen for changes in timbre and tonal quality. Before long, you’ll develop an ear for finding an instrument’s sweet spot.

Drum Kit

The drum kit is one of the most difficult sound sources to record for a couple of reasons. First of all, each drum has its own unique sound and secondly, drums produce very high Sound Pressure Levels (SPLs). That’s why, if budget allows, each one has its own mic. Choosing mics (like unis) that reject sound at certain angles can help you achieve a drum mix with fewer phase problems.

In a professional studio, drums are isolated in their own room to prevent bleed-through to microphones used for other instruments. It’s also common for drums to be placed on a riser to help reduce low-frequency transmissions through the floor.

For an open and natural kits sound, try using fewer mics or just one high quality mic placed at a distance, facing the entire kit. With a little tweaking, you may be able to achieve a nice balance that captures the kit and the room acoustics.

Keyboards

This category represents a wide spectrum of acoustic, electric and electronic instruments, each with its own special sound requirements. Listed here are some of the most popular techniques.

Upright Piano

Sound: Natural, picking up hammer attack

  • Placement: Just over the open top, above treble strings
  • Comment: Good placement when only one microphone is used
  • Shure mics: PG81, SM94, Beta91, KSM137

Sound: Slightly full or tubby, picking up hammer attack

  • Placement: Just over top, above bass strings
  • Comment: Mic bass and treble strings for stereo
  • Shure mics: PG81, SM94, Beta91, KSM137

Sound: Natural

  • Placement: Inside top near bass and treble strings
  • Comment: Minimizes feedback and leakage, Use two microphones for stereo
  • Shure mics: PG81, SM94, Beta91, KSM137

Sound: Bright

  • Aiming at hammers from front, several inches away (remove front panel)
  • Comment: Mic bass and treble strings for stereo
  • Shure mics: PG81, SM94, Beta91, KSM137

Grand Piano

Sound: Natural, well balanced

  • Placement: 12″ above middle strings, 8″ horizontally from hammer with lid off or full stick
  • Comment: Move mics farther from hammers to reduce attack and mechanical noises
  • Shure mics: PG81, SM94, Beta91, KSM137

Sound: Bright

  • Placement: Surface mount microphone on underside of lid over lower treble strings, horizontally, clost to hammers for brighter sound, futher from hammers for more mellow sound
  • Comment: Excellent isolation. Experiment with lid height and mic placement on piano lid for desired sounds
  • Shure mics: PG81, SM94, Beta91, KSM137

Electric Piano Amp

Since most electronic keyboards can be plugged right into an amplifier, you can follow miking suggestions for electric guitar. Tonal balance will depend on the brand of piano. Roll off bass for clarity and roll off high frequencies to reduce hiss.

Saxophone

Like the electric guitar, the sax has sound characteristics similar to the human voice. And that’s why the shaped response of a dynamic microphone is generally preferred. However, a miniature condenser microphone mounted on the bell often does the trick. The sound is fairly well distributed between the finger holes and the bell. Miking close to the finger holes produces key noises, so generally mics are placed toward the middle of the instrument. (Note: this technique does not apply to the soprano sax, since its bell does not curve upward – therefore, miking in the middle of the instrument won’t pick up sounds from both the key holes and the bell.)

Harmonica

Sound: Full, bright
Placement: Very close to instrument
Comment: Mic may be cupped in hands
Shure mics: 520DX (“The Green Bullet”), SM57

 

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Davida Rochman

A Shure associate since 1979, Davida Rochman graduated with a degree in Speech Communications and never imagined that her first post-college job would result in a life-long career that had her marketing microphones rather than speaking into them. Today, Davida is a Communications Manager, lending her skills to a wide spectrum of activities – from public relations and social media to content development and sponsorships.

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