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Stereo Image
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| TranceAphobic |
Hi guys
Yes the Q might sound obvious, but have to be sure.
Working on/Improving my stereo image at the moment when a Q came to mind. When the correlation is in the -1 area it tells you you're sounds are phasing, Yes ? - then by decreasing the stereo width you move back to the +1 Mono area.
I realized that when the Kick+Bass come in it hits the correlation to almost complete MONO - which is great, but lets say some of the lead or sfx sounds does phase while playing together with the Kick+Bass. Does the bass frequncies eliminate the phasing, or is it still phasing in the background ? |
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| Richard Butler |
| Put a donk on it, sorted. |
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| itsamemario |
| It will still be phasing when combined with the kick, yes. |
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| Juan Paulino |
| Only after you put a cowbell. |
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| cryophonik |
My (limited) understanding is that the phasing is frequency-dependent. I've noticed the same situation in some of my tracks, as well as in some commercial tracks. I use the Flux Pure Analyzer system, which sheds a bit more light on the issue than a standard vector scope can.
If you look at the image below, you'll see the vector scope at bottom center, with the phase indicator (green light near +1) at the bottom of the vector scope. On the left-hand side is a vertical nebula spectrogram, showing how energy is distributed across the stereo field at all frequencies, where the bottom (red/orange) is the lowest frequencies and the top (violet/blue) are the highest frequencies, and the X-axis is the stereo image (L-R).
So, if I have a section of music where there is no kick/bass or other low-end information showing in the nebula (e.g., just a vocal, piano, and pad), I sometimes notice that the phase indicator in the vector scope drifts over into the negative values, indicating a phase issue. If the same part is playing and a mono kick and/or bass is introduced, the phase indicator immediately jumps back into positive values, although the nebula shows that not much has changed in the upper frequencies. So, I'm left to assume that the phase issue is still there, but it's being masked (mathematically, at least) by the presence of the mono low end. I'm not sure if this is actually the case, though, so I guess that's back to the OP's excellent question. It looks like itsamemario has confirmed it, but is my understanding correct? |
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| derail |
I'd have to assume that the overall phase indication is some kind of average over the entire frequency spectrum - so a kick and bass would overpower the high end's impact.
I've never understood those things enough to know if it's a problem I need to worry about. I check all my stereo sounds in mono and make sure the level doesn't drop due to phase issues. As long as they still sound as good in mono I assume the mix is fine. |
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| derail |
| quote: | Originally posted by derail
I'd have to assume that the overall phase indication is some kind of average over the entire frequency spectrum - so a kick and bass would overpower the high end's impact.
A kick can't "fix" a high end sound which has phase issues.
I've never understood those things enough to know if it's a problem I need to worry about. I check all my stereo sounds in mono and make sure the level doesn't drop due to phase issues. As long as they still sound as good in mono I assume the mix is fine. |
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| DJ RANN |
| quote: | Originally posted by cryophonik
My (limited) understanding is that the phasing is frequency-dependent. I've noticed the same situation in some of my tracks, as well as in some commercial tracks. I use the Flux Pure Analyzer system, which sheds a bit more light on the issue than a standard vector scope can.
If you look at the image below, you'll see the vector scope at bottom center, with the phase indicator (green light near +1) at the bottom of the vector scope. On the left-hand side is a vertical nebula spectrogram, showing how energy is distributed across the stereo field at all frequencies, where the bottom (red/orange) is the lowest frequencies and the top (violet/blue) are the highest frequencies, and the X-axis is the stereo image (L-R).
So, if I have a section of music where there is no kick/bass or other low-end information showing in the nebula (e.g., just a vocal, piano, and pad), I sometimes notice that the phase indicator in the vector scope drifts over into the negative values, indicating a phase issue. If the same part is playing and a mono kick and/or bass is introduced, the phase indicator immediately jumps back into positive values, although the nebula shows that not much has changed in the upper frequencies. So, I'm left to assume that the phase issue is still there, but it's being masked (mathematically, at least) by the presence of the mono low end. I'm not sure if this is actually the case, though, so I guess that's back to the OP's excellent question. It looks like itsamemario has confirmed it, but is my understanding correct? |
Nice post Dave - I've not used The FPA and it looks pretty comprehensive.
Here's a post from the admin of the logic pro help forums which is one of the best descriptions of correlation meters in relation to stereo Image I've ever seen:
"+1 is in phase, or mono.
-1 is out of phase, or mono but with one of the channels reversed.
Anything in between represents varying degrees of stereo width. It is recommended to stay between 0 and +1 for mono compatibility (if you had a mix that was hitting -1 all the time, there would be nothing left when switching your monitors to mono!).
So there's no rule or goal, just to know what you're doing and what you're going for. Out of phase can sound interesting if you want a sound to appear like it's coming from outside the stereo field, but it's quickly annoying (try listening to a whole song with a channel out of phase...).
It's a compromise: the wider the stereo, the worse the mono compatibility. So ask yourself who your audience is and if they'll listen in stereo or mono. Most people don't bother setting up their Left and Right speakers in a triangle setup (as they should for proper stereo listening), so what's left is often somewhere in between mono and stereo (I won't talk about the case of the left speaker in the kitchen and the right speaker in the living-room).
So as exciting as it might sound in your studio while mixing, it might suck in a car radio, or on headphones...
The rule of thumb is: try to stick between 0 and +1 and when it's below 0, make sure you know why and you know what you're doing and why it sounds like that. Otherwise, that could mean that you're mixing signals that are out of phase, therefore losing punch and cohesiveness.
Keep in mind that when adding out of phase signals you lose a lot of energy and level." |
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| cryophonik |
Nice post, RANN (and derail)! The phase issues that I usually see are only in the mid/upper frequencies and they're usually so minor that they aren't very noticeable when mono'ed, but it is nice to have a decent metering system to help see what you can/can't hear.
I'm surprised you haven't used the FPA system - it's very nice, has a -ton of options, you can set up any custom views that you want and quickly tab between them, and there are different optional modules available for it (including a multi-channel metering option). I would think that your studio would get a lot of use out of it. I have the basic system plus the metering option. It's probably overkill for my needs, and it's normally way more than I would spend on a metering suite, but I sorta lucked out with a no-brainer deal on it when I was considering a cheaper metering suite, so I couldn't pass it up. |
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| Looney4Clooney |
| play it mono. If it sounds ok, you are fine. don't be obsessed with mono playback because they account for 1 % of your potential customers. |
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| DJ RANN |
| quote: | Originally posted by Looney4Clooney
play it mono. If it sounds ok, you are fine. don't be obsessed with mono playback because they account for 1 % of your potential customers. |
and 80% of clubs ;) |
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| DJ RANN |
| quote: | Originally posted by cryophonik
Nice post, RANN (and derail)! The phase issues that I usually see are only in the mid/upper frequencies and they're usually so minor that they aren't very noticeable when mono'ed, but it is nice to have a decent metering system to help see what you can/can't hear.
I'm surprised you haven't used the FPA system - it's very nice, has a -ton of options, you can set up any custom views that you want and quickly tab between them, and there are different optional modules available for it (including a multi-channel metering option). I would think that your studio would get a lot of use out of it. I have the basic system plus the metering option. It's probably overkill for my needs, and it's normally way more than I would spend on a metering suite, but I sorta lucked out with a no-brainer deal on it when I was considering a cheaper metering suite, so I couldn't pass it up. |
I try not to worry too much about phase issues unless I actually hear something out of whack.
I mix in stereo then check in mono. As long as it doesn't collapse in mono, I'm fine with that, but there have been times with certain phasy-lead sounds or stereo delay/spread FX where I've had to get in to checking the correlation.
Believe it or not, I've never seen a correlation meter used at the studio. Granted the first engineers are walking correlation meters, but they really just rely on their ears to check if something is funky of the spread and phase. Bear in mind, it's mostly 5.1 surround where you have discrete channels for everything so it becomes less of an issue as needing mono compatibility for 5.1 mix is not a prime consideration.
TV, yes, but that's just given a quick check on the mixcubes before printing. |
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