Stereo Miking Made Easy
A quick how-to introduction to two popular stereo miking techniques
It takes at least two microphones to create a stereo recording, but the first question is: why record a part in stereo at all? For example, an acoustic instrument (well, one that’s smaller than a piano—let’s say an acoustic guitar) is by its nature roughly a point source of audio when you get far enough away from it, so one could therefore consider it a mono instrument. Shouldn’t one microphone be sufficient?
Well, in a dense mix, a simpler single- microphone mono guitar recording probably does make sense. In a sparse mix, where the acoustic guitar is more of a feature instrument, a stereo miking technique is more desirable as it creates a sense of presence and space: the instrument may be mono, but the space in which it lives is not.
When using two microphones on a single source, a stereo image is created based on the time difference between the sounds reaching each microphone. Also contributing to the stereo image is the frequency balance of the sound as picked up by each microphone. In our guitar example, a microphone pointed at the neck will pick up frequencies different from those being picked up by a microphone pointed at the guitar body. Pan these two recorded signals left and right, and we have a pleas-ant stereo rendering of the acoustic guitar.
I’m going to discuss ORTF and XY, an alphabet soup of acronyms used to label two popular stereo microphone placement techniques. These two techniques complement each other and may be the only ones you’ll need to choose from when using stereo miking in your studio. They both use small-diaphragm, cardioid (direction-al) microphones; the difference between them is strictly in the mics’ placement.