Stereo sound is something, which makes the listening experience more enjoyable and intuitive. Without it the sound is not very immersive.
A lot of things when recorded in stereo sound much better then the plain old mono, hence this article is going to take you through some stereo miking techniques which can be used to record stereo sound.
What is Stereo Miking?
For stereo Miking, the microphones are usually used in pairs. By placing the microphone at different positions, we capture differences in timing of sound source and frequency amplitude. These slight differences in the sound of both microphones make our ears perceive the sound as stereo.
Types of Stereo Miking Techniques
XY
In this technique the two microphones are aligned in the same physical plane. They are placed at an included angle between 90 to 180 degrees. The directional response of the microphones is usually cardioid but it can be any other polar pattern as well.
Since the capsules are aligned in the same physical plane, there is no difference in arrival time of both sounds. This gets rid of one of the main localization cues i.e. arrival time. It results in an overall less realistic stereo image.
Having said that, this is still one of the most common stereo techniques a powerful sound which is needed in a lot of cases.
Spaced Pair
It is a commonly used technique that is very easy to set up. It uses two-cardioid microphones pointed directly at the sound source. The only thing is that they are separated by a distance of 2 to 20 feet depending upon the size of the source. This creates a very dramatic stereo image when the sound from the two microphones is panned hard left and right. The spectrum sounds really wide, hence giving true stereo sensation.
In-spite of all the merits there are some demerits as well:
- The sound is not very realistic, since it is too wide.
- Depending upon the distance between the two microphones, there is hollowness in the Centre while listening it back.
Mid-side (M-S)
It uses one microphones (generally cardioid) pointing directly at the source. The second microphone is a bidirectional one placed perpendicularly at +90 and -90 degrees on the sides. Similar to XY the arrival times of the sound are same (coincident).
Once the sound has been recorded, the signal of the second microphones is split and the polarity is reversed. This gets rids of phase issues. The volume ratio of the mid side signal and side signal creates different kinds of stereo images, which can be altered according to the need of the song.
This technique helps to create a realistic stereo image because there is no hole in the middle and the overall texture is very strong.
Blumlein
This is one of more interesting Stereo Miking techniques that people use.
It uses two-bidirectional cardioid microphones placed at an included angle of 90 degrees. The use of bidirectional microphones not only captures sound from the source but it also captures the sound of the room/hall. The placement of the microphone accounts for the wet versus dry ratio. This results in a very natural sounding stereo with natural reverb/room sound in it.
