A variety of distances can ube se to pickup a sound source: Close, distance, accent, and ambient. If the microphone is positioned too close to an instrument, it may only capture part of the sound. Conversely, if the microphone is too far away, it may struggle for sound level and it will pick up more ambient reflections than direct sound.
Close miking involves positioning microphones around 1 to 30 cm from the recording source. It is often used to create a clear, tight, present sound, as it effectively excludes the ambient's reflected sound. However, it is subjects to leakage, as it can also pick up the sound of nearby instruments. With a proper balance of volume input, leakage can be minimized. Other ways include putting up barriers between the sound sources, using cardioid patterns and spreading the instruments farther apart.
As a rule when we have many instruments, for every unit of distance between a microphone and its source, the nearest other microphone should be positioned at least 3 times the distance away. This is called the 3:1 rule and also prevents phase issues.
When microphones are placed too close, the timbre of the instrument may be lost. Therefore, a proper close distance should be chosen.
Distant miking involves positioning microphones at least 2 m or more from the sound source. It is used to preserve tonal balance and add natural ambience to a sound. A natural tone balance will often be achieved by placing the microphone at a distance roughly equal to the size of the instrument.
Used with large instrumental ensembles, distant miking relies upon the integrity of the acoustic environment. A balance must be chosen so that the microphones pick up a good level of direct and reflected sound, without the reflections exceeding the direct sound.
If the ambient is not fit, its improper reflections can cause the sound to become muddy and less defined. Moreover, at certain random heights a hollow sound might be created, due to phase cancellations that occur between the direct sound and the delayed sounds that are reflected.
Accent miking involves positioning a microphone at some distance between the distant microphones and the sound source. It is used to increase the presence and volume of an instrument, as in the case of solo instruments.
Ambient miking involves positioning a microphone at such a distance that the ambient reflections are the most prominent. A twin stereo cardioid microphone is the elective choice to add a natural ambience to the recording - which is often lost with close miking.