Coincident Pair

When recording drum kits, pianos, string sections, or small ensembles the use of stereo miking techniques can make your job much easier. You don't have to focus in on each individual instrument or singer and can instead use a minimal microphone setup to capture the ensemble as a whole. By using these techniques you can retain the stereo image from left to right, you get a sense of depth in the recording, and get a good sense of the acoustic space it was recorded in.

There are four general techniques used in stereo recording, the one I will focus on today is coincident pair. This technique involves the use of two directional microphones placed with their grilles nearly touching and their diaphragms angled apart. The types of coincident pair techniques I will discuss are X/Y and M-S.

X/Y is one of the most common stereo miking techniques used. It utilizes two identical, or a stereo pair, of directional microphones. While you may think that the setup should look like an 'X', it actually resembles a 'V', with the capsules coming together as close as possible at a 90 degree angle.

M-S stands for mid-side and utilizes two microphones, one directional microphone pointed towards the source and another figure-8 microphone placed to pick up the sides. The microphones are placed with the capsules nearly touching just like the X/Y technique.

M-S is great for getting a good stereo image when you want the focal point to be in the center of the ensemble. This technique doesn't work as well the bigger the ensemble gets, however, because it tends to focus more on the center section due to the directional microphone being used.

This technique has no phase issues in stereo and is mono compatible, so your sense of a stereo image remains. A good use for this technique is to use it as a room microphone setup. It can often times sound more natural than a spaced pair.

To set up M-S on your mixer requires a few additional steps:

• First, create two new tracks in your session (one stereo and one mono) and label them as Side and Mid respectively. 
• Next patch from the Side Channel to a Mult and from the Mult to two channel inputs, or patch from the Insert Out of the Side Channel to the Insert In of the next channel. This will split the signal coming from the figure 8 microphone onto two separate channels. 
• Next you will flip the phase of one of the channels dedicated to the Side Microphone and run a tone generator through the channels.
• Bring one fader up and slowly bring the second up until you find the "null" point where the sound cancels 100%.
• Pan both tracks hard left and hard right. 
• Bring up the level of the Mid Microphone and you are ready to go.

Which of these setups do you prefer when choosing which stereo miking technique to use? Do you use the M-S technique as a room miking technique often? Let me know in the comments below.