Out of phase guitars

[Colorblind]

I was doing some guitar tracking last night and was pretty happy with the overall sounds. 2 amps, 2 mics on each amp. Listening back today, I realized the signals from amp #2 have their polarity flipped in relation to those from amp #1. When I "correct" those tracks by flipping the polarity, the guitar sound is much more full, as you'd expect, but I kind of miss some of the midrange stuff that I was hearing with them out of phase. Not sure if I should be leaving them in phase and EQing them to bring out some of the detail I'm missing (which I suppose could create other phase issues unless done globally), or just leave them the hell alone and enjoy their inherent weirdness. I realize I'm using phase and polarity interchangeably here, but I think y'all get the drift.

Wondering if (m)any of you are purposefully making things out of phase somewhat regularly, and in what cases have you found it to be most useful?

[Recycled_Brains]

I've never done it purposely myself, but when I was taking a Pro Tools class in college (2003 or 2004), the teacher had the session file for Lenny Kravitz's version of "American Woman", and he showed us how the engineer had purposely offset the waveforms for the 2 mics on his guitar cab to make the sound you hear in the main riff.

Listening to that now, I wouldn't know it was out of phase if I had never been shown that.

I don't think I'd do it that way, but I do often EQ separate mics on the same cab differently. That's more to avoid redundancies in certain frequency areas though.

[digitaldrummer]

if it gets you the sound you want, then go with them out of phase. there a no rules saying they have to be in phase. besides, nobody else will be able to tell in the full mix.

[ashcat_lt]

You didn't ask, but of course the final polarity of the output of any given amp depends on a number of things. Most preamp tube stages are inverting, so how many of those it goes through makes a difference. In some amps, one channel will have a different number of inverting stages from the other, so it will be different depending on which hole you plug into. Then, of course, speakers can be wired differently. Even guitars can be wired differently, so just switching guitars into the same amp can make this happen. That's before we start talking about pedals even.

I agree with the above that you should just do whatever sounds best in context. Keep in mind, though, that the "OoP" version will only cancel frequencies that are close to each other in level. You might could cut some bass from one of the two and hear more low end from the mix of them, hopefully retaining the midrange weirdness that you like.

[Nick Sevilla]

If it sounds right, it is right.

Don't change them, UNLESS you need way more of the in phase tonality overall.

Weird is good.

[drumsound]

How do the two amps sound in mono through just one speaker? Phase is measured in terms of degrees. 180º will cancel completely, which I doubt is happening, but between 0-180º will leave more of the sound and might work. If in mono it was "a little thinner on the bass" but had something cool in the upper mid, it might be fine. If, however in mono the guitars just sound thin, and annoying, I'd reverse the polarity of one amp and EQ the midrange back in.

[digitaldrummer]

of course, you could always use just one track (one mic) too. I often record more tracks than I actually use...

[vvv]

Other possible tricks:

Dupe the tracks, and pan so the In Phase is to some extent on one side and the Out Phase is on the other and try to balance them.

You could also add the slightest delay to one of either the original two, or one or two (pick a number) of all four tracks (pick a combination), or of just one phase state mixed mono.

Or mix mono and take, say, the Out Phase track and smash it to Hades, and then bring it up with the In Phase tracks - try playing with the panning.

Or pass filters on say, the mono Out Phase mix might could help when used with the In Phase (either mono'd itself or panned against itself.

Or you could use reverb or other modulation on one or more tracks.

And variations/combinations thereof ...

[Colorblind]

Cool. I'll probably experiment with it a bit more, but I'm leaning towards just letting it fly as-is.

Most preamp tube stages are inverting, so how many of those it goes through makes a difference. In some amps, one channel will have a different number of inverting stages from the other, so it will be different depending on which hole you plug into.

That's interesting. I was using an AC30 with one of those Epiphone 5-watt heads through a 1x12. I recently used the AC30 in combination with another amp going through the same 1x12 with the same mic setup, and everything lined up polarity-wise, so it sounds like maybe it's the inverting stages mismatch you mentioned.

How do the two amps sound in mono through just one speaker? Phase is measured in terms of degrees. 180º will cancel completely, which I doubt is happening, but between 0-180º will leave more of the sound and might work. If in mono it was "a little thinner on the bass" but had something cool in the upper mid, it might be fine. If, however in mono the guitars just sound thin, and annoying, I'd reverse the polarity of one amp and EQ the midrange back in.

They sound ok in mono through one speaker, just less bottom end than when I flip one. All mics were the same distance from each speaker, so the signals line up perfectly on the timeline, it's just that one amp's waveform goes up, and the other goes down. I've always taken that to mean that they're 180 degrees out of phase with each other, but being that they aren't identical signals, they don't cancel each other out.

of course, you could always use just one track (one mic) too. I often record more tracks than I actually use...

I used to record a single amp, single point of collection for the longest time, but I got one of those Radial Shotgun boxes so I can start experimenting a bit more with multi-amp setups. Results have been mixed, but I'm finding it to be worth the extra setup time. I can always ditch any additional tracks that don't serve the song.