Sound Recording with Ambient Microphone Placement
Ambient miking is simply placing the mic far enough away from the sound source so that you capture more of the room sound (the reverb and delay) than the sound of the actual instrument in your recording. You may place the mic a couple of feet away from the source but pointed in the opposite direction, or you may place it across the room.
You can even put the mic in an adjacent room, although admittedly this is an unorthodox technique. The distance that you choose varies from instrument to instrument.
Ambient miking definitely has its place, but using this technique requires forethought. Consider the following items when you use this technique:
You lose the attack of the instrument. Because the mic is so far from the sound source, it picks up more of the ambience of the room than the attack of the instrument (hence the name of the technique). To counter this effect, use distant or spot mics for the instruments that you want to have a more pronounced presence and blend these mics with the ambient mic when you mix.
You need a good room. Ambient miking relies on the sound of the room to create a pleasing ambience. If your room doesn’t sound great, you’re better off using a closer miking technique instead.
On the other hand, if you can find a great room in which to record — a church or auditorium, for instance — setting up a mic in the middle of the room (you must listen for the best placement by walking around the room as the music plays) can give your tracks that extra something that can set them apart from the run-of-the-mill home recordings.
Placement is key. Just as each instrument has a sweet spot, each room has a place that sounds best. Take your time finding this location and put your ambient mic there.
Watch for phase problems. Because an ambient mic is typically used in conjunction with another mic or two (or more), you must keep the relationship among the mics correct; otherwise, you’ll have problems with the phase of the recorded waveforms.
Ambient mic placement works well in those places where the room adds to the sound of the instrument. The sound that you record is ambient (hence the name). If you mix an ambient mic with a spot mic, you can end up with a natural reverb.
So if your room doesn’t add to the sound of the instrument, avoid using an ambient mic. You can always add a room sound by using effects in the mixing process.