Stereo Microphone Techniques You Should Know

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It is amazing how one inch can change how recordings would sound. In recording distances, often times differ the way microphones were situated. Depending on how long they are far away from each other or how close they may seemed. Because of this, it allows us to explore more on the variety of ways on how to record music.

Stereo miking techniques differ in terms of width and positions of the microphones as it mimics our two ears in order to record the perfect music. Our ears compares sounds received in terms space, distance and location of the sounds we heard. Sounds differ because of the distance between our two ears. Perception varies because of the two differents signals received by each ear.It is analyze different by the human brain. Interaural Timing Difference occurs because of the different timing that sound signal is received by both ears while Interaural Intensity Difference happens because we absorb energy from the sound signal travelling to our auditory system.

Even if stereo miking technique imitates the ITD and IID perception of our ears there still some factors that affect how sound differs.So how do sound engineers come up with techniques to make sounds more natural to our ears?

A/B Stereo Recording

A/B Stereo recording is done by facing two omnidirectional microphones with a short diaphragm condenser directly towards the direction of the source of the sound. The microphone should be one foot away while the microphone should be two feet away from each other. When applying this technique make sure that you experiment on the distance in order to get the preferred tune that you want. The distance of the microphone represents the distance between the ears. In this, the stereo image would stagger a little, due to the ITD to make a sound recording. The frequency balance would be different because of the added stereo width. However,because the distance, it will cause an offset on the timing between the microphones causing a phase cancellation when stereo and mono are combined

Mid/Side Stereo Recording

mid/side recording technique

photo source:http://www.uaudio.com/webzine/2005/december/text/content4.html

Mid-side Stereo recording often times use two mics, one with a small diaphragm condenser microphone either cardio or omnidirectional. The second microphone, should have a large diaphragm condenser microphone. The microphone with a large diaphragm condenser mic should be place 90 degree. This microphone will record the sound on both side.The mic with a smaller diaphragm is positioned above or below the second mic. The smaller mic would function as the mid microphone.In this, it is very difficult to replicate the side channel. You need to reverse the polarity of the channel being duplicated and combine the two side channels into one stereo track. Mixing the mid channel with the stereo channel helps adjust the width.The higher the level of the side channels, the higher the stereo width. The Midside recording is very difficult to replicate but it has a greater advantage compared to the other techniques. It gives a better stereo width and mono capability and lets you adjust room ambiance to replicate a Blumlein Pair Technique

X/Y Stereo Recording

For X/Y recording, we recommended to use a two directional mics that has a smaller diaphragm condenser. When positioning the the mics, you have to place it in an 90-135 degree angle so that the capsules so that they would meet at a single point. The wider the angle the wider the stereo image. The process of mixing the sounds is pretty much the same process of the A/B Recording. This technique may have a less stereo effect because of its position where they meet at the same point and the differences in timing will have no changes. The stereo effect however will have differences of the frequency balance. But the good thing about this, there won’t be mono phase cancellation.

ORTF Stereo Recording

This technique uses two directional mics, preferably the ones with a smaller diaphragm condenser. In this, Microphones are spread outwards forming an angle about 110 degrees and the capsules are spread apart by 17 centimeters. Mixing the sound signal is pretty much the same with A/B stereo recording however it differs to how it sounds. It is a mixture of the two different technique however it picks up less of the ambient room sound.

Blumlein Pair

Blumlein Pair Technique

photo source:http://www.harmonycentral.com/articles/blumlein-pair-stereo-miking-for-better-ambience-and-imaging

For Blumein Pair, you are going to use two mics that are bi directional. It should be the same position with X/ Y technique. Mixing is pretty much the same with X/Y technique. But compared to the X/Y technique,It picks up better room sound and adds more ambiance to the stereo image using the bi directional microphones.
These techniques vary to different conditions of the room. It is very important that you take note of the different techniques to be able to properly execute and which would work on specific conditions.

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