Recently, I've been focusing on understanding the importance of phase in both production and mixing. When checking a string section that a composer programmed for me some time ago, I noticed it lost strength and impact when played in mono. When analyzing it with a phase correlation meter, I observed that while not out of phase entirely, there are certain frequencies which are out of phase for a couple of seconds:



In some parts, even for a couple of seconds, the meter displayed negative values, indicating phase cancellation in certain frequencies. I've watched several YouTube videos that address how to "fix" this issue in already recorded tracks, but they often seem to provide contradictory advice.

Some people suggest using a plugin to reduce the stereo image, while others claim that this doesn't actually solve phase correlation problems, even if the meter suggests otherwise. Is this true?

Another approach I've come across involves applying an equalizer in mid-side mode with linear phase and applying a low cut in the side channel. This seems to solve the problem but can result in a loss of stereo width as the cut is increased. Here's an example of how the strings turned out when applying this method with the equalizer:





How do you approach these types of phase correlation problems? I appreciate your help in advance.

 

Last edited: Sep 16, 2023

Just add Nugen Audio Aligner to all your channels and let it do it's magic.

https://nugenaudio.com/aligner/

 

I'm using a stone old MB widener to narrow the according freq ranges.

 

Does that string section NEEDS to be at the front&center of the stage? If yes, the answer is simple: put them there. Make the sound mono (or narrow it), make sure the other instruments don't interfere with that main sound and there you have it.

We don't need all the sound in the mix to keep the same level when collapsed to mono. Is actually smart to have secondary sounds wide, so when the mix collapses to mono, we clearly hear the main elements of the song, while the secondary go few dB lower in volume.

Also, the metering is just vaguely informative, I would not rely on it ot the point of commiting the sound to look good on metering. You can often find yourself looking at a "wrong" audio (metering-wise) that still sounds good.

 

Very good question. I want the string ambience track to be stereo since it adds a creepy vibe to the track. Thanks for the answer.

 

In my experience the most still reasonable sounding solution to solve this, is to cut side and boost mid to the same amount. Just making things more narrow with a stereo processor does not sound good to me.

 

Leapwing's StageOne 2 has a phase recovery algorithm, but I haven't checked it yet.

 

Don't bother too much about meters specifically. The way you heard issues when summing to mono is enough. Now, what to do with it.

First, simply ignore it ¯\_(ツ)_/¯
Try to mix it so it still fits its place and does its job in mono, and being more flavourful in stereo would be a nice bonus. Might "narrow" it a bit so it doesn't stand out too much.

Second, tell the composer that their strings are too damn wide and that they should fix the issue at its source. Really, that's the best option if it's available.

Third, if you really want some of the Stereo flavour in Mono, Mathew Lane DrMS can take some signal from Side channel and phase-flip it into Mid channel and vice versa. You can do it by hand, the math is simple, but the routing might be cumbersome, plus DrMS has a lot of contingencies built-in.

Fourth, use Mid/Side EQ to remove a consistent excess in some freqs of a Side channel if it is present.

 

Another thing you can try is compressing/limiting the sides, either manually or with something like Sideminder.

 

Learn about the Mid-, and Sides channel - and how they complement each other in a balanced stereo recording/mix/master.

Width is "phase issue". There's no way around it. It's just when the width (and the phase issues) gets over-representated that it becomes a problem (in mono-compatibility).

A stereo widener/booster/enhancer is basically a M/S mixer. With it you can either up the Sides, or down the Sides. It's a good tool whenever you need to make the stereo image less wide (as well as more wide).

If you just want to reduce the Sides/width on a specific section where the Sides is taking over, you can use a dynamic EQ in Sides mode and set a threshold and ratio to where you control the loudness of the Sides volume (in the affected frequency range).

 

Great answers! One more idea; extract your preferred L or R signal (mono) then use something like Leapwing StageOne to create a fake stereo effect that is mono compatible.