Nugen, makers of such plugins as Halo Upmix and the Paragon reverb have offered Production Expert readers a free copy of their phase alignment tool Aligner.
What Is Nugen Aligner?
Aligner is a plugin which automatically corrects destructive phase cancellation caused by time of arrival differences between multiple audio channels carrying similar content. To put it more simply it can fix thin, phasey sounding audio when combining multiple microphones which can all hear the same thing.
Classic examples which benefit from this kind of treatment include:
Multiple microphones on a guitar amplifier
Multiple microphones around a drum kit
Combining a DI and a microphone on an amplifier on bass
It is possible to manually align tracks on the timeline of your DAW, though this is laborious, and when setting mics on sources like amplifiers it is possible to place them very accurately to avoid these issues at the recording stage but a plugin like Aligner can automatically analyse and correct time and polarity issues at the touch of a button. While manually correcting two sources is reasonably straightforward, correcting multiple mics, for example on a drum kit is more challenging and this is where an automatic time and polarity adjustment tool like Nugen Aligner becomes indispensable.
Why Does Phase Cancellation Occur?
In the picture above you can see the two mics are very similar distances from the speaker, however they are not an identical distance from the speaker and because both the ribbon of the 4038 and the diaphragm of the 441 are hidden from view inside their housings, visually aligning them is difficult. Some cancellation will occur. How much depends on the relative distance between the mics and the speaker and the bigger the difference the lower down the frequency spectrum the cancellation will occur. At small distances the effect is likely to be negligible, but as the difference extends into inches and then feet the cancellation can extend down into the bass. If the difference is great enough then the signals are no longer ‘correlated’, meaning that they are so different that they no longer cancel.
Exactly why this cancellation occurs can be best explained by comparing waveforms on the timeline of a DAW:
In the example above you can see how, if the two signals are summed, if one is going up, when the other is going down, the results will be a reduced output, if the signals are exactly the same but one is the inverse of the other then they can cancel each other out completely. While this can be easily fixed by inverting the polarity of one of the cancelling signals, a much more likely situation is that the signals will cancel each other a bit, but not completely, due to one signal being delayed compared to the other because it has taken slightly longer to reach a microphone which is further away. This is the issue Aligner is so good at fixing.
To get your free copy of Aligner click the button below.
Photo by Caught In Joy on Unsplash