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Eventide Staff
Hi Mosvalve,


A couple people have added this, so I just wrote a new section for the manual.  However, I'm copying it here to help answer your question too.  Please let me know if this helps.


What Does this Plug-In Do, and How Do I Use it?

The primary use of Precision Time Align is to align the outputs of several microphones placed at different distances from a sound source, correcting the phase cancellations that can arise from mixing multiple microphones together.


Any time you place a microphone near a sound source the recorded audio is delayed by the distance from the source to the microphone. The time of this delay is determined by the speed of sound.  If you place two microphones near the same sound source, but at different distances from it, the resulting waveforms in your DAW will be similar, but delayed with respect to one another.  This can cause comb filtering whereby some frequency bands cancel each other when the two signals are mixed together.  This often makes the combination of the two signals sound worse than either track soloed.  


This problem can be partially addressed by shifting one of the recorded tracks relative to the other in your DAWs arrange view.  However, this is a tedious process which requires you to use your eyes to align the tracks rather than your ears, which are the proper tool for making things sound good.  Precision Time Align is designed to allow you to quickly and easily align these tracks, while listening, and with much higher precision than you are able to in your DAWs arrange view.


To do so follow these steps:

1. Record and Solo Two Tracks

For this to work you must record two tracks of the same instrument.  This is usually two microphones on the same source, but can also be two of the same signal which has run through different convertors or digital effects units, or anything which applies a relative delay tho two signals which are very similar.  Also, the more frequencies contained in these signals the more opportunities for cancellations, so the more important the alignment will be.  One of the most common problems is a close and far microphone on a distorted guitar cabinet.


It will be easiest to hear these effects if these two tracks are soloed, but if you'd like to hear it in the context of a mix it is not required.


2. Instantiate Precision Time Align on One of these Tracks

It often helps to instantiate the plug-in on the far microphone (or later track) and pull it towards the close mic using Precision Time Align's negative delay feature by pulling the delay slider to the left.  However, you can pull the close microphone backwards to the far microphone by pulling the delay slider to the right, as well.


3. Invert the Phase

This step is optional, but I find it easiest to invert the phase (or really polarity) of the signal in the Precision Time Align and try to find the point of maximum cancellation between the signals, then turn off the Phase Invert to get minimum cancellation.


4. Use the Coarse Adjust Slider to Find Maximum Cancelation

If the phase is inverted you want to find the amount of delay that totally cancels the two sounds, or comes as close as possible.  As you sweep the Coarse Adjust Slider the two signals should sound like a flanger.  You're looking for the highest frequency flange you can find with this control.  As it gets very close to the proper point the signal level may begin to drop as the signals are cancelling.


If the phase is not inverted, you will still aim for the highest frequency flange, but you're now trying to find the least signal cancellation instead of the most, which will mean the loudest signal.


If you already have a good idea of the relative offset between the two signals, you can enter this delay amount in mS or samples.  Or if you have a good sense of the distance between the microphones you can enter this distance in feet or Meters.  Either way, you should always follow the next step and fine tune by ear.


5. Use the Fine Adjust Slider to Really Find Maximum Cancelation

Once you get the Coarse Adjust Slider to the highest frequency flange, or most quiet audio, use the Fine Adjust Slider to really dial in the point where as much of the signal as possible cancels out.  You might find that at different overall delay settings, different frequency bands in the signals will cancel.  If this is the case, you can decide which frequency bands you'd like to stand out in your mix by selecting either as an artistic decision.


Remember as long as Phase Invert is on, anything that is cancelled now will be present, and anything you can hear now, will be cancelled in the next step when you…


6. Un-Invert the Phase

Once you've found the maximum cancellation, un-invert the phase to hear how your two microphone signals blend.  At this point you can play with the relative levels of your signals, or continue to use the Fine Adjust Slider to dial in your desired sound.  Also, bypassing the plug-in will allow you to hear the difference between your modified and unmodified mixture.


7. You're Done

Once you understand the workflow of Precision Time Align you should be able to reproduce these steps very quickly and naturally.  We hope it's a great time saver and helps you achieve the best mixes you can.