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Out of phase: Move mic or use invert phase switch? Audio Interfaces
Old 2 weeks ago
  #31
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Quote:
Originally Posted by Mosby View Post
Not to be a nag here, but phase is different then ploarity... sometimes they can be the same thing, or changing polarity fixes the phase...

The switch on your mic pre, that's polarity. One of the results of flipping this switch is that, the phase will be 180 degrees opposite from what it was. But that's a polarity adjustment that can, sometimes, correct a phase problem.

Phase, is more traditionally, a time based thing. For example, issues can arise when recording a bass guitar through a DI and mic'ing the cab. The DI signal will reach the "tape" quicker then the mic'd signal (remember, sound takes time to move from the cab to the mic). now the delay between the two signals will likely not be huge, but it is enough that one waveform will be "offset" from the other. This could cause phase problems in that they are not "in time" with each other.

I feel llike I'm bastardizing my explanation of phase nad polarity here, so I'll leave it at that. Remember, just because you mic'ed both the top and bottom of the snare, it doesn't mean that you have have to flip polarity. Solo both the top and bottom snare channels, and flip the polarity. Listen to see if the sound gets hollow, or if it gets more full. If it gets hollow that's a decent indicator that phasing might be at work. The reality is it might sound better with out the polarity flipped (or it might not - use your ears).
You actually understand and explained the two quite well.

There are some things that can be added.

First off - sound waves all travel at the same speed in a given medium. For example, Sound travels through the air at approximately 340 meters per second. It can vary depending on how much humidity and temp but travels slowest through the air. Humidity makes air more liquid and sound travels much faster through liquids (1,480 m/s) or solids (5,120 m/s through iron) Solids are 15 times faster then dry air.

Phase and Polarity are only an issue when more then one mic is being used on the same source. If the sound being recorded isn't being captured by another transducer then its not going to have any phase issues with other tracks already recorded or recorded after.

Phase is the result of two waves being out of time and the resultant waves are either partially or completely subtractive. (or partially additive/not additive depending on whether your glass is half empty of half full)

In phase means two waves are in sync with one another, both going north and south at the same time so there is no wave cancellation.

When waves are maximum 180 degrees out of phase, the waves should cancel each other out if they were identical in shape and amplitude. That's extremely rare of course so it would simply cause a maximum amount of cancellation or a Null.

The Chances of two waves being 100% in phase or 100% out of phase are only one in 360. There are 360 degrees in a cycle and the odds where a polarity switch is going to fix a phase issue are practically zilch.

The ideal way to match two mics is using a dual trace oscilloscope. You cane feed two mics a test tone then move one mic till the signal aligns with the first. The time sound takes to travel through the air is what causes the phase shift so its simply a matter of creating the proper length between the two to get the farther mics signal to rise in sync with the first.

There are cycles lost because the second mics begins after the first and there may be amplitude and decay differences between the two signals as well.

I should add, flipping the mic polarity reverses the current flow direction in a mic. Reversing its magnet (if it has one) would accomplish the same thing.
If a mic or mixing board doesn't have a phase switch you can always use a short XLR cable with the leads on one connector reversed.

Typically you wouldn't want to mess with polarity, especially when using phantom powered mics. Having the power applied to the wrong leads is looking for trouble so I'd only recommend using a reverse polarity on non powered mics, and even then you could simply move the mic to put it in phase. If you do have a mic which has a reverse polarity of others then reversing the primary transformer leads to the mic element would probably be the wisest long term solution. I believe most mics produce a positive going wave when there is an increase in air pressure and the diaphragm is pushed in. It produces a negative wave when its sucked out.
Old 2 weeks ago
  #32
I would always try to get it right during tracking. Tiny brought up a very interesting point. I would use the polarity switch as a last resort, and don't forget about modern technology! If you can just slide it in phase in the DAW, try that as well.
Old 2 weeks ago
  #33
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Sigma's Avatar
esp on bass di/bass mic the slide works best you shift it till it works best with song/kick
Old 2 weeks ago
  #34
Gear Guru
I noticed I have the polarity switch on my mic Out. If I switch it to In and record a new track is it going to be screwed up in an already existing song which was recorded with the polarity reversed?
Old 2 weeks ago
  #35
Quote:
Originally Posted by Wayne View Post
Since you opened this back up... from my post 12 years ago;
haha. Yup as I was typing the title for a new thread this popped up and was almost identical... And with the other responses that have been left I'm quite glad I did.

Quote:
We are picking mic positions (phase/time) and -polarity- (the static best 'in or 'out condition) looking for favorable complimentary combinations.

You're damn right it's tougher for us in our one or two open room setups w/o decent isolation from the sources ..let alone if you're also bouncing back and forth from the kit to play back.

Out of phase: Move mic or use invert phase switch? Yes

There is the slight 'reprieve in that phase cancellations are only at their worst (strongest) when the out of time sources are mixed at near equal levels.
That means if some things are lower in the mix, so are what would have been those side effects. (same as the 3:1 rule of attenuating- but via distance, unwanted out-of-time bleed effects
I was aware of the differences between "phase" and "polarity" but some very good insights from you comment and others.

I also don't believe I took into consideration about the effect, or lack there of, when some signals are lower in volume/amplitude. Good to know.

I guess I was guilty of just hitting the "phase" button when the wave form polarities were not in sync. Most the time it did sound "better". But, I'm going to get back to moving mics around until the cycles are more inline with one another.
Old 1 week ago
  #36
the question remains: totally out-of-phase or just a bit?
Old 1 week ago
  #37
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Quote:
Originally Posted by Raaphorst View Post
the question remains: totally out-of-phase or just a bit?
Yes, no and none at all I guess would be the answer -depending on the freq.
Old 6 days ago
  #38
Here for the gear
Quote:
Originally Posted by fastlanestoner View Post
I would always try to get it right during tracking. Tiny brought up a very interesting point. I would use the polarity switch as a last resort, and don't forget about modern technology! If you can just slide it in phase in the DAW, try that as well.
Agreed. Although I don't recommend purchasing the plug-in that the following videos accompany, the videos do provide good examples of this subject - courtesy of Waves Audio:

Phase Correction Plugin – InPhase | Waves

Once all aspects of a live drum recording (audio waveforms) have been time aligned, the decision to flip phase on a few tracks is a matter of taste.

I've always thought this issue was 'the nature of the beast' when recording drums. I have since purchased a digital drum set and mastered the art of drum replacement for these exact reasons.
Although implementing the process of drum replacement and sequencing/quantizing the resulting MIDI information may take longer, I have found my clients are ultimately more satisfied with the more audibly clean and sequenced audio, especially in instances of live concert recordings.

As a result of using drum replacement, mic bleed is significantly reduced and the quality of the resulting overall audio recording is significantly improved - IMHO of course.

Best wishes on the journey!
Old 6 days ago
  #39
Lives for gear
Quote:
Originally Posted by DrStrangeBeat View Post
Agreed. Although I don't recommend purchasing the plug-in that the following videos accompany, the videos do provide good examples of this subject - courtesy of Waves Audio:

Phase Correction Plugin – InPhase | Waves

Once all aspects of a live drum recording (audio waveforms) have been time aligned, the decision to flip phase on a few tracks is a matter of taste.

I've always thought this issue was 'the nature of the beast' when recording drums. I have since purchased a digital drum set and mastered the art of drum replacement for these exact reasons.
Although implementing the process of drum replacement and sequencing/quantizing the resulting MIDI information may take longer, I have found my clients are ultimately more satisfied with the more audibly clean and sequenced audio, especially in instances of live concert recordings.

As a result of using drum replacement, mic bleed is significantly reduced and the quality of the resulting overall audio recording is significantly improved - IMHO of course.

Best wishes on the journey!
You sir are the devil.
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