Using Multiple Microphones on sources is a great way to thicken up and contour the sound of a recording. That being said, it also has the potential to introduce some un-welcomed issues if not done properly.
Generally speaking, when I’m using Multi Mic setups to record a source, I’m paying careful attention to the phase relationship between both microphones and the source. Flipping (or inverting) the polarity on one of the channels is a great way to check this.
Example: When using a Top Microphone & Bottom Microphone on a snare drum - in order for the phase relationship to be correct - the bottom mic would need to have its polarity inverted . Failure to do so may result in a a thin, weird sound - that loses all it’s bottom end.
But not every case is this cut & dry. For instance in the case of using multiple microphones on an Acoustic Guitar track - it’s not really a case of using a Top & Bottom Mic, where one of them will be 180 degrees out of phase with the other. Having said that - inverting the phase of one of the channels may still very well provide telling results. But furthermore, it may be a case where the phase is “close” but not perfect.
In these cases, I usually try to aim to get things as close as possible while tracking, and if I feel there is a need for further refinements - I will turn to good old trusty manual editing in my DAW.
BUT before I go, one thing I wanted to add (that I really should have mentioned in the video), is that if you can visually see that the waveforms are completely out of phase with each other - you’d definitely want to make sure to invert the phase using a plug-in such as Mix Tool in Studio One. And it might even be worth rendering this into the file using Event FX - so that visually the Waveform updates. The way to see this visually would be that the Waveform would be going down (from the Centre) as opposed to going up from the centre.
In this video I demonstrate some basic concepts on how to fix the phase of multi mic performances using basic editing when working In PreSonus Studio One. And to be clear - this is assuming that the Audio files are both generally ‘in phase’ to begin with.
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