Spaced Pair (Omni-Directional or Cardioid)

The spaced pair mic placement is great for small to large groups of instruments (Jazz trio to large Orchestra). The mics themselves are placed 6 feet above the ground and 6 to 8 feet apart forward facing the group. You can use either omni-directional mics or cardioid. If you want less audience noise/sound then use the cardioid pattern. For better sound quality then Omni's usually work better but with the increase in background (reverb) and audience. A third mic can be used for soloists without to much difficulty.

The problem that arises when using Spaced pair miking is that the delay times between the mics can result in comb filtering (a bad thing in this case). This is caused by the signal path lengths being different. This problem has been addressed using the X/Y configuration.

X/Y Configuration

The X/Y Configuration is used to counter the center image localization problems. This setup involves using two matched cardioid microphones that are mounted on the same mic stand. They are placed close together and are angled at about 60 to 120 degree at the capsules. This angle will change the coverage area. Many engineers use 90 degrees and super-cardioid.

Each mic should be as close to one an other as possible. There are mic adapters that allow you to mount two mics on a single stand. I use this configuration for drum overhead but it can be used anyplace a stereo pair is called for. As far as using them in a studio, I start out with each mic panned to hard left and hard right (hard left means panned all the way to the left). I then use headphones and solo the over head mics and have the drummer play or hit the cymbals (left and right sides of the drum set) then change the angle of placement. Use which ever angle sounds best. Different rooms also give different results in how the mics sound. You may have to move the mics closer or further away from the set. Sometimes having them directly overhead doesn't sound as good or as natural as having them placed a couple of feet in front of the drum set. The height of the mics also change the sound. This miking technique is also called Coincident Pair Miking.

The closer the mics are to the sound source the better or more 'stereo' the sound is while moving them away gives you more of a mono room sound.

Mid/Side

The Mid-Side miking technique requires two different types of microphone polar patterns: Cardioid, and Figure-8. This is probably one of the best and most accurate stereo miking methods you can use. The problem with this is it must be decoded into stereo. Encoding and Decoding is very simple and if you are using Nuendo/Cubase or a VST application you can use the Stereo Tools VST plug-in to Decode your Mid-Side encoded track.

As mentioned this mic placement technique requires a Cardioid Mic that is positioned in front of and facing the instrument. This mic is the "MID" signal and captures in MONO. A figure-8 mic (the SIDE) is also used in this configuration. It is sensitive to sounds coming from the front and the rear of the mic. You'll position this mic right below that of the Cardioid mic with the front of the mic facing 90 degrees to the left. This is what gives you the stereo width and is used to capture sounds from the left and right sides of the stage/area. Depending upon the mic itself will determine what actual position the figure-8 mic is to be placed under the Cardioid.

With these two microphones you end up with two signals but it isn't a stereo signal. The Cardioid (MID) mic is panned to the center with the Figure-8 (SIDE) mic routed to two different channels on the mixer. Pan one of these channels to the LEFT and the other to the RIGHT. Then turn on the Polarity switch for the RIGHT channel. This will invert the phase of the signal. While having an equal amount of signal present in both mics (amplitude is the same) you then can decode the MID-SIDE signal back into the stereo signal. You can change the width of the stereo spread by changing the amplitude of either MID or SIDE channel.

For more CENTER information then raise the MID (Cardioid) channel, for more stereo width then lower the (Cardioid) etc...

If you are recording this into a digital audio workstation such as Nuendo or Cubase you can use the Stereo Tools VST plug-in and select the Mid-Side button. This will decode the M/S encoded track without all the extra work. You can change the volume of the LEFT channel on the plug-in to change the width of the stereo image.