Doubletrack guitars in negative phase...

Discussion in 'Recording Studio' started by Antiphase, Aug 31, 2020.

  1. Antiphase

    Antiphase SS.org Regular

    Messages:
    73
    Likes Received:
    16
    Joined:
    Aug 20, 2016
    So I recently experienced this thing, it`s been a long time since I used correlometer because I forget things from time to time, but now I`m using it again and it clearly shows my guitar bus in negative phase. I usually pan guitars hard left and right and each of those is also displayed in negative phase unless I pan those close to center. What`s really got me is that phase inversion makes 0 difference, which is strange because I thought that`s what it exists for. It looks like in most projects it`s enough to pan guitars 75% to be more or less fine on corrrelation meter, but I don`t like such a sound. So should I just ignore it? I`m not really experienced but I`ve heard there would be mono-compatability issues, and guitars might disappear. I don`t think I have any true mono devices to tell it though. Any advice is appreciated, thanks!
     
    c7spheres likes this.
  2. DudeManBrother

    DudeManBrother Hey...how did everybody get in my room?

    Messages:
    2,232
    Likes Received:
    2,187
    Joined:
    May 3, 2014
    Location:
    Seattle
    If your correlation meter shows tracks are in the negative, then zoom in as close as necessary and try to line up the wave forms reasonably close. Every note will have a slightly different attack and decay, which creates a different wave form. Everywhere one guitar’s wave is going up, and another down: you will have phase cancellation. Everywhere they are generally going up and down together will sound nice and full. There will be a small window where the phase coherency is at its best.

    It is true that phase issues will really show up in mono; but that should be a low priority reason to worry about correlation. People listen to music in stereo. I think it’s dumb to make mix decisions for someone listening over a phone loudspeaker or on a mono Bluetooth device. I’d always strive for a great mix that can be appreciated on a decent stereo or set of headphones, with mediocre playback over someones iPhone speaker, than vice versa. Fix the phase issue because it’s going to make the guitars sound better overall, not just for mono compatibility.

    If fine alignment still isn’t quite solving it for you: try a pitch adjustment tool. You can adjust your left side by +6 cents, and your right side by -6 cents (as an example). This will harmonically excite different frequencies, thus subtly shifting the wave forms, and can help correlation. You might have to experiment with values a little, but I’ve usually had luck around the 6-18 cents range.
     
    gabito, Antiphase and Hollowway like this.
  3. Antiphase

    Antiphase SS.org Regular

    Messages:
    73
    Likes Received:
    16
    Joined:
    Aug 20, 2016
    The trick is with pitch is something new, I`ll try it. So is it ok though that hard panned guitars on their own are in negative phase and it doesn`t invert? Like left guitar isolated is negative, so is the right one.
     
    Last edited: Sep 1, 2020
  4. DudeManBrother

    DudeManBrother Hey...how did everybody get in my room?

    Messages:
    2,232
    Likes Received:
    2,187
    Joined:
    May 3, 2014
    Location:
    Seattle
    The way you pan a track has no direct effect on the source phase. It can help poor correlation to a degree, but the tracks themselves don’t start moving phase until you add eq, saturation, and additional stereo width (beyond hard panning). Think of it like this: When the mic diaphragm gets pushed back the wave is down, and when it’s pulled out the wave is up (It could be the reverse of this, but the point is the same).

    You only really flip phase on a guitar track when you’re using multiple mics. If the diaphragms aren’t lined up, they will receive the sound at different times (hence the necessary zoom in track alignment) and in some cases one mic is getting pushed while the other is pulled out. Different guitar takes are similar to multi mics. You play everything slightly different so there will be certain parts that don’t quite align, but it’ll sound good as long as most parts do. Only invert the phase on them if all your other tracks are out of phase with the guitars.

    The only time phase reversal is basically mandatory is when you mic the top and bottom of a drum. The hit of a snare will pull the top mic’s diaphragm out, while the energy of the same hit will push the bottom mic in. The majority of the waveform will be out of phase, and cause a ton of cancellation. They are different enough that you’d still get sound, but it’ll be real thin. Once you flip the phase of one mic, depending on the waveforms of the other drums, you can get all the body and punch back.

    You want to see all your tracks going up and down at relatively the same time. Every time there is opposition (which is inevitable and happening often) those frequencies will cancel out.
     
    Last edited: Sep 1, 2020
    Antiphase likes this.
  5. Antiphase

    Antiphase SS.org Regular

    Messages:
    73
    Likes Received:
    16
    Joined:
    Aug 20, 2016
    ok, I guess I`ll just leave as it is :)
     
    DudeManBrother likes this.
  6. fantom

    fantom Misses his 6 strings

    Messages:
    590
    Likes Received:
    457
    Joined:
    Mar 8, 2009
    Location:
    Bay Area, CA
    Ya I'm pretty sure two completely different takes don't need phase adjustments. It's really only when you use multiple mics on the same take.
     
    Antiphase likes this.
  7. jaxadam

    jaxadam SS.org Regular

    Messages:
    2,483
    Likes Received:
    1,628
    Joined:
    Aug 14, 2006
    Location:
    Jacksonville, FL
    Username checks out.
     
    c7spheres and Drew like this.
  8. odibrom

    odibrom .

    Messages:
    3,960
    Likes Received:
    1,814
    Joined:
    Dec 2, 2014
    Location:
    ... perto de onde a terra acaba e o mar começa...
    I double record my guitars, the signal comes from my Triaxis' Record Outs into the audio interface. Yeah, no optimal but it's what is possible at the moment. I use a G-Force in the Triaxis' FX loop, so sometimes the signal comes stereo, so there it goes, 2 tracks at one take, NO MICS or CABS used, so no phase problems there to start with.

    Recently I've made an experiment on having one of the tracks in reverse phase. While hearing in the stereo panorama, it kind of felt bigger sounding and that is gratifying and interesting. The problem arose when some friends hear the recordings in mono systems, some replied there was no guitar or it couldn't be heard... it turned out that it was due to that little experiment, placed the tracks with the same phase and problem solved... just sharing, I'm not a guru in mixing nor sound engineering.
     
    c7spheres and Antiphase like this.
  9. Drew

    Drew Forum MVP

    Messages:
    29,903
    Likes Received:
    5,810
    Joined:
    Aug 17, 2004
    Location:
    Somerville, MA
    Even then, I generally flip phase BEFORE recording, and once I've got my "primary" mic sounding as good as I can get it, I'll flip phase on my secondary mic and position it to make the guitars sound as weak, fizzy, and hollow as possible. Then, once I'm sure they sound like absolute shit, I can be pretty sure there's significant phase cancellation going on, so when I un-flip phase, suddenly they're going to sound pretty huge.

    You can also go at it using phase cancellation creatively, and trying to get it to cancel in ways that work for you artistically... but I tend to fall into the analysis paralysis rabbit hole if I try to do that and go mad trying to decide which ever-so-slightly-different alignment between the two mics sounds the best to me, so this is a pretty safe way to get something that sounds full that won't paint me into a corner when it comes time to mix down, and where I won't have to worry about any unintended consequences of varying the balance between the two tracks down the road in the mix.
     
    c7spheres likes this.
  10. DudeManBrother

    DudeManBrother Hey...how did everybody get in my room?

    Messages:
    2,232
    Likes Received:
    2,187
    Joined:
    May 3, 2014
    Location:
    Seattle
    There’s a recording method where you point a cardiod mic at your guitar cab, as well as a figure 8 mic to capture the sides. You then flip the phase of the fig 8 take to create a stereo depth, but the track completely disappears in mono. You’d get stereo width and mono compatibility that way.
     
  11. TonyFlyingSquirrel

    TonyFlyingSquirrel Cherokee Warrior

    Messages:
    4,146
    Likes Received:
    1,104
    Joined:
    May 4, 2006
    Location:
    Auburn, Washington
    This is referred to as “Mid-side” mixing.
    https://www.uaudio.com/blog/mid-side-mic-recording/
     
    c7spheres likes this.
  12. c7spheres

    c7spheres GuitArtist

    Messages:
    2,953
    Likes Received:
    2,581
    Joined:
    Jan 13, 2017
    Location:
    Arizona
    - Another option is to have the double tracked guitars playing as normal however you want to mix them in stereo, but then choose which track to loose in mono so there is no mono compatible issues. You can do this so one track only exists in stereo while the other exists in both mono and stereo. It works great for guitars that have the same riff and not completely different parts on each side. If each guitar is doing different riffs then obviously that's not what you'd want.
     
  13. c7spheres

    c7spheres GuitArtist

    Messages:
    2,953
    Likes Received:
    2,581
    Joined:
    Jan 13, 2017
    Location:
    Arizona
    Like what he's saying here too. By implementing a mid side processor for each track independently and using them as one mid/side matrix you can control only the mid or sides. By doing this you'll see the settings on the corellation meter change as you adjust the mid and side channel levels. You can effectively invert the stereo image so L=R and R=L but the faders adjust the in between of that rotation so you can get the correlation to where you want it exactly and in between too. It takes rerouting of the channels. Default values in Reaper won't get you there. You just set it up manually using routing and faders the old school way. In the end what you'll find is that it either works or not for the project/guitar tracks because you m ay or may not have enough middle for what you want in the mix along with the correlation you want too. usually it's workable, ime. Doing this is easy enough once you get the hang of it but at first it's a chore. Sometimes it's easier to just rerecord the guitars how you want them and get it correct from the source if it's really bothering you.
     

Share This Page