Скачать или смотреть Comb Filtering & Phase Correction explained - How to FIGHT Phase Issues -

Comb Filtering sounds or so-called 'Phase issues' make your mix less transparent, roomy and thin? Learn how to do phase correction within seconds in this tutorial.

Read on website: https://www.forward-audio.com/comb-fi...

In this episode of #faTutorial we’re gonna talk about these issues that are often simply called ‘Phase Cancellation’ and how to fix them within music production environments such as small microphone arrays like a guitar recording.

In the audio community there is always big confusion about the distinction of the terms 'Being out phase', 'Phase cancellation' and 'Comb filtering'. Many audio engineers try to solve these issues intuitively and try to work their way around the core of the problem.

Before we discuss this matter in detail let's start with a fundamental question: What is phase?

Phase describes the position of a period process, such as a sine wave. The phase offset between two waves of the same frequency can be described between 0° and 360°. If these two waves have a certain offset which is not 0° or 360° they cancel each other out, partially or in case of 180° completely. This phenomenon is called
'Phase cancellation' or in a more common way 'Phase issues'.

To demonstrate how this sounds I've prepared a speaker setup which plays a burst of white noise. White noise is the best way to demonstrate these kinds of problems as it contains all frequencies of the spectrum equally. As soon as we have two microphones in front of the speaker, who are not placed equidistant, we get period
cancellations all over the frequency spectrum. This looks like a comb if displayed in a (linear) spectrum therefore the name: 'Comb filter' or 'Comb filtering'.

This horrible sounding comb filter distortion is always present if you record a sound source with several not equidistant microphones. The best example is a drum recording, which is the prime example for a challenging comb filter / phase alignment situation. But there also situations like acoustic and electric guitar recordings that can have difficult comb filter distortions.

The term 'phase issue' in this regard is technically correct but often misleading. It indicates that you can describe a phase offset between two mics. But in reality a phase offset is always bound to a specific frequency. It would be more precise to simply call it a 'time difference'.

A recent study showed that the occurrence of comb filter is highly depended on the volume difference between your microphones. The surprising fact is: Comb filters are still audible up to a volume difference of 18 dB (depending on the source material).

The perception of Comb filter is also highly dependent on the instrument you are recording. Snares, for example, have the highest perception level of comb filtering of all instruments.

Furthermore, there are certain microphone distances which are easier perceivable for phase cancellation as other. Generally speaking mic distances between 15 cm and 100 cm are most likely to have audible comb filtering.

But does this mean that we have to avoid these critical distances under all circumstances? No, because there's an easy solution: With digital sample delays we can simply align these tracks together. In the example in this video I'm using our Phase Alignment Plug-in faTimeAlign (former label faFractionalDelay) to completely resolve the phase
issues between both mics.

If we talk about Comb filtering we strictly have to distinguish between acoustical and electrical comb filtering. In the previous shown examples the comb filtering happens when two or more signals are summed either digitally in your DAW / interface or in an analog mixer. But comb filter can also occur naturally in your recording studio / room because
of reflection of sound waves on the walls etc. That means acoustical treatment of your room acoustics is also very important!

I hope you found this tutorial helpful. If you want more awesome tutorials like this consider subscribing to our channel or go to forward-audio.com and subscribe to our newsletter!

Thanks for watching.

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Soundtrack: Bensound - Rumble found at: http://www (dot) bensound (dot) com/

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