Old 01-27-2019, 04:14 PM   #1
future fields
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Default Why am I having to phase invert harmony guitar parts?

I'm recording all my guitars via DI (no mics) using the same plugins in all instances. I double track rhythm left and right, no issues there.

Issue comes when I do a lead down the middle and then a harmony lead down the middle. With the phase invert button unselected on both channels the sound becomes tinny and choked and the harmony and lead parts sound like they are canceling each other in certain frequencies, hit the phase invert button on one channel and the sound becomes fuller and the harmony and lead part can both be fully heard.

From what ive read, when recording guitars seperately there should be no phase relationship so why is this happening?
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Old 01-27-2019, 04:50 PM   #2
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It is possible the harmonies are generating some harmonics that cancel with the original line but it shouldn't be drastic. Can you post separate file examples of each?

Did you use the same cable both times? Another possibility is the polarity of two cables are different.
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Old 01-27-2019, 05:10 PM   #3
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Are you using a different pickup? Is it wired out of phase?
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Old 01-27-2019, 07:40 PM   #4
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It sounds like your speakers are out of phase
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Old 01-27-2019, 08:02 PM   #5
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What is the Harmony track playing, is it different notes. If they are different notes it would be weird for them to be having that kind of phase issues. However, if the notes are the same, then there's definitely going to be phase issues, especially if they are both going down the middle.
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Old 01-27-2019, 09:02 PM   #6
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Quote:
Originally Posted by Philbo King View Post
It sounds like your speakers are out of phase
If the tracks are lined up down the middle I think it would have been noticeable from just one track but yes, definitely rule out speakers by using headphones or turning one speaker off.
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Old 01-27-2019, 09:16 PM   #7
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Quote:
Originally Posted by Philbo King View Post
It sounds like your speakers are out of phase
I'm using headphones
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Old 01-27-2019, 09:29 PM   #8
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https://soundcloud.com/mikethemental...ies-phase-test

same passage repeats twice
first without phase inverted
second with phase inverted

you can tell just looking at the waveform there are slight differences
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Old 01-27-2019, 10:15 PM   #9
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They only sound different in the second half of the riff when you switch to playing the same note in both parts. That is to be expected, really.

Any other difference is just wave cancellation which is happening all the time no matter what the sources are.

With distorted guitars, you are looking at a lot more potential for interference because you are accentuating the harmonics of the notes.

The same reason why a power chord sounds so fat with distortion on it

Below are two sine waves in perfect fourth (which is what your using mostly in that riff) with distortion added:



The two highest peaks are the original waves. But with distortion you can see we also get harmonics above and below at substantial volume and these are bound to interact with each other.
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Last edited by Fergler; 01-27-2019 at 10:25 PM.
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Old 01-28-2019, 08:52 AM   #10
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Quote:
and then a harmony lead down the middle.
I assume you are not actually playing a separate harmony part... You are using a harmony effect, right? Where the harmony part is derived from the lead?

Different delay/harmony/chorus/ADT effects will behave differently but these things can happen since the 2nd waveform is derived directly from the 1st because the phase relationships are determined by a computer algorithm.

If you play the parts separately the phase & timing differences will be random and this shouldn't happen.
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Old 01-28-2019, 11:56 AM   #11
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Quote:
Originally Posted by DVDdoug View Post
I assume you are not actually playing a separate harmony part... You are using a harmony effect, right? Where the harmony part is derived from the lead?

Different delay/harmony/chorus/ADT effects will behave differently but these things can happen since the 2nd waveform is derived directly from the 1st because the phase relationships are determined by a computer algorithm.

If you play the parts separately the phase & timing differences will be random and this shouldn't happen.
I'm playing all parts seperately
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Old 01-28-2019, 12:18 PM   #12
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It's generally not a good idea to double guitar lines using the same tone. The waves will be too similar and will likely cause phase problems. Best thing is to change guitars and/or amp for overdubbed guitar, esp if they play the same part. You'll get a bigger, more characterful sound this way too.
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Old 01-28-2019, 12:21 PM   #13
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Quote:
Originally Posted by DVDdoug View Post
If you play the parts separately the phase & timing differences will be random and this shouldn't happen.
And sometimes the timing/phase will be near identical and things will cancel/add - pretty much everything we ever hear is due to some cancellation somewhere. I see this when a guitarist is extremely tight with themselves and play the same part, once performance for the left and one for the right, when they happen to line up perfectly, they will sort of jump to near mono for a moment. I suspect the OP is experiencing something like this, except it's already in mono and they are just hearing the stuff that matches up (or rather off just enough to cause some cancellation) - aka what Fergler said.
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Old 01-29-2019, 01:30 AM   #14
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Quote:
Originally Posted by karbomusic View Post
And sometimes the timing/phase will be near identical and things will cancel/add - pretty much everything we ever hear is due to some cancellation somewhere. I see this when a guitarist is extremely tight with themselves and play the same part, once performance for the left and one for the right, when they happen to line up perfectly, they will sort of jump to near mono for a moment. I suspect the OP is experiencing something like this, except it's already in mono and they are just hearing the stuff that matches up (or rather off just enough to cause some cancellation) - aka what Fergler said.
Seem like the most likely cause.

The one thing I might try to narrow it down is just copying the first track to another track to see if it does the exact same thing.

If it isn't really along the same line when an exact double is playing against itself, it is most likely what Fergler and Karbomusic are discussing.
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Old 01-29-2019, 01:36 AM   #15
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One other thing that occurred to me while listening on earbuds...

Sounds like the harmony is there in the left if you take the right earbud out as well as the right if you take the left earbud out.

Is that the case? While it sounds like what you are describing, I just want to be sure.

If so, you could try to some panning closer to hard left and right(let's say one part at three o'clock and the other at nine o'clock) and see if the issue you mentioned seems as pronounced.
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Old 01-29-2019, 08:39 AM   #16
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Are you using two mono recordings - or are you using two recordings from a VST amp sim which are stereo each?

You should normally be safe as you describe it if doing mono recordings.

But two stereo - becomes a mosh if blended like that.

Anyway, Waves S1 Stereo imager is really useful
https://www.waves.com/bundles/gold

Gold bundle contains muchos goodies 30+ plugins for $99 right now. Including S1.

I use S1 for many things, like narrowing leslie from hammond, which usually is full stereo and things like that. You can set it to occupy 1100-1400 or so in pan if you want.

But as always with spatial kind of processing - check in mono also to see nothing surprising is happening.
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Old 01-29-2019, 08:44 AM   #17
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..continued, for some reason I cannot post edited posts....

Fake stereo is often created by doing 180 degrees phase between channels. So blending two of them later, not good.
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Old 01-29-2019, 05:06 PM   #18
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Quote:
Originally Posted by Nip View Post
Are you using two mono recordings - or are you using two recordings from a VST amp sim which are stereo each?

You should normally be safe as you describe it if doing mono recordings.

But two stereo - becomes a mosh if blended like that.

Anyway, Waves S1 Stereo imager is really useful
https://www.waves.com/bundles/gold

Gold bundle contains muchos goodies 30+ plugins for $99 right now. Including S1.

I use S1 for many things, like narrowing leslie from hammond, which usually is full stereo and things like that. You can set it to occupy 1100-1400 or so in pan if you want.

But as always with spatial kind of processing - check in mono also to see nothing surprising is happening.
I dont use any kind of stereo enhancement stuff

The guitars in question are both panned center, mono tracks

Rhythm guitars i double track, using two different guitars, and pan 100% left and right

When i listen in mono it sounds like shit, almost like somebody turned a flanger pedal on

I dont copy paste anything, when i double track i play the part again

I dont edit my playing either. Like shifting notes around and stuff. Quantizing the audio. None of that in my music
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Old 01-29-2019, 05:28 PM   #19
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Quote:
Originally Posted by future fields View Post
I dont use any kind of stereo enhancement stuff

The guitars in question are both panned center, mono tracks

Rhythm guitars i double track, using two different guitars, and pan 100% left and right

When i listen in mono it sounds like shit, almost like somebody turned a flanger pedal on

I dont copy paste anything, when i double track i play the part again

I dont edit my playing either. Like shifting notes around and stuff. Quantizing the audio. None of that in my music
To repeat, I'd try just copying one of the tracks(probably the initial one that you later harmonized) to a second track without the harmony even coming into play.

If you listen to them in mono and there's no issue, the problem is likely the very nature of harmony guitar/doubling.

If you listen to them in mono and there is an issue, there's probably another issue and it's time to start trying to isolate it if it's a big enough issue.
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Old 01-29-2019, 06:15 PM   #20
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Would not matter what instrument it was - you will be faced with phase issues attempting to use software for harmonies involving the source audio being played with the harmonized audio.

Try this with a vocal or a bass and see what a horrible phase mess you are dealing with.

To expect them to be perfectly in phase is IMO impossible.

Play the harmonies on the guitar - or live with the phase issues.
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Old 01-30-2019, 08:59 AM   #21
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Quote:
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Would not matter what instrument it was - you will be faced with phase issues attempting to use software for harmonies involving the source audio being played with the harmonized audio.

Play the harmonies on the guitar - or live with the phase issues.
OP's most recent comment clearly states he is playing the parts separately, and not using any software methods to double/harmonize.

Fergler answered the question on Jan 27.
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