To begin with, let’s sort out what Mid-Side technique is. It was invented by Alan Blumlein in 1933, and apart from the symbol “Mid-Side”, “Middle-Side” and “M-S” stand for it in English and widely used in music mixing and mastering studios around the globe.
There are a lot of techniques of stereo sound recording with microphones (for more info see articles in the section “microphones and recording”), Mid-Side technique is one of them. Its advantage is perfect mono compatibility on mixing. That is if your stereo recording can be decoded into mono, the sound recorded with the help of Mid microphone will remain in it. That is exactly why this method is often used in sound recording on television. Even if your recording is guaranteed to be played back in stereo (yet it’s practically impossible), with Mid-Side technique you’ll receive stereo which has no problems with decoding into mono.
After recording with the help of such a couple of microphones (cardioid and bidirectional), you can diversify stereo pan on sound mixing by adding new effects and instrument parts. Before recording, place microphones perpendicularly and as closely to each other as possible. After recording the sound, the left channel is formed by the addition of microphone recordings, and the right channel is formed by the subtraction of the channel of a bidirectional microphone from the channel of a cardioid microphone (Mid + Side = Left; Mid – Side = Right). How to implement addition and subtraction?
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