This quick tutorial shares how to use a correlation meter, what to do with the results it gives you and how to troubleshoot and resolve phasing issues in your music.
Phasing issues can haunt us as modern producers. From boxiness to completely missing audio, phase alignment problems are something you always want to avoid. Luckily, most DAWs have a correlation meter for you to use. These small utility plug-ins can be a real lifesaver, as unassuming as they may appear at first glance. They are very simple in their design, providing you with meter showing a range of -1 to 1 but most do not offer any kind of help or explanation on the surface. So we are here to explain how it all works.
A correlation meter registers a +1 value when audio signals being measured are in perfect phase alignment and a -1 value when the signals are offset to the point that they can cause serious issues. These helpful meters cannot always alert you of phase issues in your projects, but they can be a big help in identifying and tracking them down. For instance, two duplicate sounds become slightly offset in your arrangement resulting in a very boxy and warped quality of sound. Obviously this is unwanted and it is because the two audio signals are not in perfect phase alignment. The correlation meter may not show anything to make you aware of this particular problem. Therefore we still need to be very aware of any small audible changes as we work to avoid surprises like this one.
If a correlation meter does happen to show you a problem exists in your mix, you may try (slightly) shifting one or more of the audio regions in your arrangement to alleviate the problem. If this does not work, you can use a simple gain plug-in to invert part of the signal or even convert the signal to mono right there on the spot. Certain types of plug-ins may cause stereo imaging and phase correlation issues. If you are having a tough time tracking down where the phasing issue is originating from, you may want to bypass any stereo imaging/spread plug-ins to see if they are the cause. There are many ways a phasing issue may creep into one of your music projects. But knowing how they happen, being as pro-active as possible to avoid them and being systematic in your approach to isolating them when they occur will help you greatly in your battle against them. Always use a correlation meter!
Cheers,
OhmLab