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I have an inexpensive Zoom recorder with mics swappable into X/Y position. How should I go about recording ambient sound (street, etc.) while avoiding phasing issues? Is that even a possibility in real world considering physics? Does using X/Y configuration help?

The purpose of recording is most likely later use in music (possibly video) production. The intent is to capture sound close to how it would be perceived by the hearer, but ideally with less chance of phasing issues making it easier to mix for audio systems other than headphones.

Relatedly, should I change mic configuration or where I point the recorder depending on whether I record general scene or focus on a sound of interest?

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    Can you explain more about the phasing issues you’re trying to avoid? Can you try recording in mono? Jan 19, 2023 at 12:17
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    X/Y being a coincident system, you shouldn't have phasing issues when summing left and right channels.
    – audionuma
    Jan 22, 2023 at 8:11

2 Answers 2

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It was only a phase...
I remember phase issues after summing to mono was quite a big problem in the past. It's not such a big problem now, as there aren't many mono playback devices left in use.
However, to me, it's still pretty much a must to fix them, as I can hear most larger phase issues on my headphones, and I also see them in various displays I use to monitor things like stereo width as I mix, so I like to get it clean as soon as they show up (usually due to extreme effects). I hate it when I hear different kinds of shifting phase issues on TV, too. To me, it's quite unprofessional.

My limited knowledge on field-recording:
Microphones aren't really my thing, though, so I don't know if field recordists worry about phase issues at recording time that much. But intuitively, I think it would be worse for things relatively close to the mics, of different distances from each mic, of lower frequency, and with increasing the distance between the mics. But I'm guessing there (They may be some fading uni lecture memories).
I'd just listen live and on playback, with decent monitoring headphones, flip between mixing the mics (Mono) and separating them to L/R and see if anything becomes apparent and if so, try varying the technique.

Why is X/Y stereo micing better with regard to phase issues?
Let's start at the beginning - The brain learns the differences in transferred sound arriving at the head from different directions and uses this information to estimate the direction and distance of sounds, as well as environmental features. A big part of this is relative differences between the left and right auditory systems. One of these relative differences is the intensity of the sound, another is the time the sound arrives. Naturally, when a sound reaches two receivers at different times, the two signals are going to be out of phase. This is fine - until you need to add them together.
The AB microphone technique utilises this natural delay, as well as sound level, to create a more spacey, more "realistic" stereo image. But the downside is that when summed to mono, the same sound in both signals but at a different phase can manifest as comb filtering.
The X/Y microphone technique attempts to keep the stereo image while, ideally, removing the delay by positioning the diaphragms as close to the same position as possible. This means the sound will arrive at both mics at virtually the same time. So for X/Y, the stereo image is simulated using only sound level differences in the microphone's angled pickup patterns.

So that's why you're not likely to have phase issues with X/Y - the sound arrives at both mics at virtually the same time, meaning they're in phase. There are other techniques in the first link below, but that's pretty much as far as my knowledge on microphone technique goes.

-Useful links-
Stereo Recording Techniques and Setups (DPA)
Head Related Transfer Function (Wikipedia)
Comb Filter (Wikipedia)

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  • This was useful. A question: “try varying the technique”—my biggest challenge is that I plan to walk around recording sounds in real-life environment, and would have limited ability to re-record. Thus I was wondering what measures (if any) I could use at the recording stage; I recall reading that X/Y position offers less realistic stereo image but also fewer phasing issues but I’m hazy on that. Dealing with phasing later in mixing is definitely a concern worthy of research but at that point if I’m unclear I’d better post a separate question I suppose. Jan 24, 2023 at 5:58
  • @AntonStrogonoff Yeah, handling phase issues is not straight-forward and it takes some experienced/knowledgeable fiddling. I added some stuff about AB and X/Y to the answer. Hope it helps!
    – n00dles
    Jan 24, 2023 at 23:16
  • Thanks! This explained in simple terms what I sort of knew but wasn’t sure about/didn’t know why. I guess X/Y is a safe bet, though I’ll sacrifice stereo fidelity; if I want to keep wide stereo image I should use AB but be prepared to monitor for and eliminate phasing issues in post. Jan 25, 2023 at 9:31
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    Yes, but you could also try using one of the other techniques, which are sort of in between AB and X/Y. That's why I said vary the technique - to a point where phase issues are subtle enough that they don't need to be handled. I think you just need to read up on techniques, then get out there and get some real-world experience with it. Good luck with it ;)
    – n00dles
    Jan 25, 2023 at 16:48
  • Thanks! I also just found that reasonably compact ambisonic microphones can be found not cheap but I guess not outrageously expensive, I guess when using those handling phase will be all about monitoring phasing in the mix because it’s not just two but at least four mics in AB (CD?) configuration Jan 27, 2023 at 3:26
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Phasing issues only occur if you are putting two sound waves together and the waves cancel each other out (e.g. summing a stereo recording to mono.) If you are recording stereo then there won’t be any phasing on stereo playback. If you aren’t going to play it back in stereo then just use one side.

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  • I kind of knew that phase is a non-issue when you listen in headphones, but I had an impression that it’s possible that poor phase management could cause glitches (especially in lower frequencies) when playing back the mix on imperfect audio equipment. Jan 23, 2023 at 11:42

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