Microphone Recording Distance
The distance of the microphone from its source can have a dramatic effect on a recording.
It can be a real problem trying to find the right distance to mike up a sound source. If the microphone is positioned too close to an instrument, it may only capture part of the sound, but on the other hand, if the mike is too far away it may struggle for level and it will pick up more reflected room sound than the direct sound.
There are standard distances and positions for most instruments, but as with choosing the correct microphone, it must be stressed that these are starting points only.
Close miking involves positioning microphones around 1 to 30 cm from the recording source.
The close technique is widely used in the industry to create a clear, tight, present sound. As sound diminishes the further from the sound source, close-miking picks up a high level compared to that of distance miking.
Close miking effectively excludes the room’s acoustic reflected sound. However, it can be renowned for leakage; a condition whereby the instrument’s microphone picks up the sound of nearby instruments.
Leakage is problematic when it comes to the mixing process as several signals can be combined together onto one channel, causing level and phase problems. The key is to try and avoid leakage by:
- Placing microphones closer to the instruments
- Putting up barriers between sound sources
- Using uni-directional polar patterns
- Spreading instruments farther apart.
When several instruments are being recorded it is wise to incorporate the 3:1 distance rule (for every unit of distance between a microphone and its source, the nearest other microphones should be positioned at least 3 times the distance away). Adhering to the 3:1 rule prevents phasing issues and leakage problems.
It is important to realize that microphones should be placed close to the sound source as is necessary, not as close as possible. If microphones are placed too close, the timbre of the instrument may be lost.
Experiment by moving the microphone around until the desired sound is achieved.
Distant miking involves positioning microphones at least 2m or more from the intended sound source.
The distant miking technique is used to preserve tonal balance and add a natural ambience to a sound. A natural tone balance will often be achieved by placing the microphone pick up at a distance roughly equal to the size of the instrument or sound source.
Distant miking is often used in the pickup of a large instrumental ensemble, such as a symphony orchestra. In such a situation, the pickup relies upon the integrity of the acoustic environment and the microphone is placed at a distance that strikes an overall balance between ensemble and environmental acoustics.
Distance miking does have the potential to ruin a track. Some room acoustics can produce improper reflections causing the sound to become muddy and less defined. Soundproofing/acoustic treatment to the space can help in cutting back these deficiencies.
If the distant microphone technique is used, placing it at a random height can create a hollow sound due to phase cancellations that occur between the direct sound and the delayed sounds that are reflected. It is best to experiment with various heights until the desired sound is achieved.
Accent miking involves positioning a microphone at some distance between the distant mikes and the sound source. The accent miking technique is used to add a touch more presence and volume to an instrument that needs it, such as a trumpet doing a solo passage.
Accent pickup should sound natural and not overly present.
Ambient miking involves positioning a microphone at such a distance that the reverberant is very prominent. A twin stereo cardioid microphone is best used to provide a natural ambiance to the recording.
Ambient miking is generally used in large halls to restore the natural reverberation that is often lost with close miking.