Ambient producers: How do you deal with phase correlation problems?

[Lygiro JT]

I've watched a lot of YouTube tutorials on ambient music, but I've noticed that very few of them really dive into the topic of phase or phase correlation properly. Even those who mention it often do so in a very superficial way. Personally, I've experimented with tools like PaulXStretch, and while I manage to get very interesting sound textures, I've noticed that phase correlation tends to be lacking when I analyze it using a specialized meter like Voxengo Correlometer.



This issue also extends to many techniques related to using reverb and to synthesizer patches or presets designed for creating ambient soundscapes. It seems like many ambient music producers focus on achieving a wide and stereo sound, but they often overlook the challenges that phase and mono compatibility can pose. Some have suggested that they can fix phase correlation issues by using stereo widening plugins to "shrink" the stereo image. However, I wonder if this solution is truly effective or more of a quick fix or a gimmick.

I've seen another method where a mid-side equalizer is used to apply a high pass cut to the side channel with the intention of "fixing" phase correlation problems. According to this technique, the phase correlation meter shows positive results, indicating that the phase is in good shape. However, in my experience, when I listen to the patch/effect in mono, I still perceive that several elements of the stereo field are canceled out.



How do you approach this phase correlation challenge in your ambient music productions? Any tips or recommendations?

[foosnark]

If it's always got negative correlation throughout the entire spectrum, the entire time, you can invert the polarity of either the L or R channel and it'll be positive. It's rarely that easy though.

You can also try to delay either the L or R side (which works well if you know the phase offset is due to a latency difference, like from mic placement) but I don't find it the easiest approach for the situations I end up in.

I'm a big fan of RJ Studios Sideminder ZL, for an automatic fix that, in a lot of cases (where you've got a too-wide reverb for instance) it works pretty well and doesn't require any other work. But if you see it tightening up the width too much, or it just sounds weird, that's a sign of problems that should be fixed another way.

One example patch might be a droning triangle oscillator into two independent delays on the L and R channels, with delay times being subtly modulated by two LFOs at different rates. Sometimes the phase correlation is going to be positive, sometimes negative.

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Sometimes just inserting Voxengo MSED in Decode mode, as if your signal was already M/S and you're converting to L/R, will do the trick. it also gives you easy mid and side gain knobs. For this particular example, if you try that and monitor in mono, you will only hear one of the LFO'd delays, the other will cancel out completely... maybe not what you want.

Negative phase correlation always means that in mid/side, the side is louder than the mid. So you can use a mid/side peak EQ to scoop out a few dB on the side, and boost it by an equal amount (or less/more to taste) on the mid. A low cut on the side is never a bad idea either to keep the sub-bass region centered. I like CraveEQ for this, because it just makes this particular task really easy with its display.

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Adjusted right, this maintains positive phase correlation at all times, just by centering those stronger resonances but leaving the rest alone. It sounds different but fine if you collapse it to mono. In this case I think giving a bit of high shelf boost to the mid (no need to cut on the side) also helps maintain a similar sound in mono.

You generally don't have to worry much if the correlation is just barely above zero, or even exactly zero (90 degree phase offset), or if it very briefly dips below zero in a particular band or even overall. It's just a more sustained negative correlation, or one that waves up and down a lot between positive and negative, that can be a problem. (Or, of course, you can hear the cancellation when you monitor it in mono.)


A couple of other things I like for mid/side processing:

Noise Engineering Librae. It's a compressor with slightly unusual controls, and four stages -- a stereo pre, a mid and side, and then a stereo post. I don't tend to use it to compress heavily, but it has some saturation/distortion options. I find that a little soft drive on the side channel can often enhance the image without substantially making it louder (and there's a goniometer in the plugin to help a bit).

Wavesfactory Equalizer is an auto-EQ plugin with a mid/side knob... sometimes I find either leaning toward mid or toward side with the auto cutting and boosting can work nicely.

[MogwaiBoy]

I make ambient-"based" music and phase is a big deal for me as far as mitigating it where possible and accepting what I'm sacrificing in mono. I do make more structured/melodic-leaning ambient electronic stuff though, so generally it has near-mono bass/sub and other instrumentation (strings, pads, synths, even leads) which I don't want to sacrifice in mono - but wide background pads can take a hit.

It's simple for me: mono still needs to be able to carry the track and not have anything important missing. It's like any other music, then.

Using lots of modulated reverb etc can create phase issues for sure, so it's just about being aware of it.

Use mono to create contrast, because if everything's wide, nothing's wide.

[joshsolomon_]

I always just checked in mono and im good to go.
If the sounds I want to hear are present in mono then im good.
Im so confused about the over emphasis on fixing phase correlation problems lately when I simply just check the track in mono.
Is there is something else Im missing about this?

[bmanic]

Phase correlation can play quite a big role in how things sound in a club, especially if they have tons of speakers all over the place. So if your music will be playing in a club it is usually a good idea to not have things too out of phase below 150Hz or so. It can lead to some pretty weird sounding issues.

Other than that, no, it doesn't really matter in my opinion.

For a "quick fix" you can use the rather expensive Stageone plugin from Leapwing. It can force stereo correlation, even in the bass. Basically taking out of phase stuff and forcing it into the normal L/R field. Doesn't always sound good though.

Or you could try Tone Projects Basslane Pro which allows you to extract the side information and force it into normal l/r phase which then sums correctly into mono. Again, it's a bit hit and miss.

[foosnark]

I actually don't care about mono compatibility that much, clubs, or vinyl cutting. But the stereo image of my music in general improved once I started paying attention to this stuff. Also under some circumstances, bad phase correlation in headphones can give you sort of a seasick feeling.