Define "phase"? Or is it polarity?

[Sonixx]

Your equations simply are a mathematical representation (with some extra glitz throw in in for physical material limitations) of the idea that a time shift on a sine wave yields results that resemble a coherent phase shift.

the math is a representation of what happens when two mics record the same signal but have different distances from the point source. Time enters into the calculation.

This was agreed to by me and everyone else long ago. But that is exactly the point I am making that everybody is getting wrong. Time is NOT required to effect or define a change in phase angle.

I see, I guess everyone else includes everyone that does not understand the difference between Polarity Inversion and Time based effects.

Direct proof #1 of this is right in that Wikipedia chart. It's staring us right in the face The difference in phase angle between the two waves is exactly pi/2 rad - a.k.a. 90°. Yet there is no shift or difference in time.

the X-Axis is Time

You reply on Wikipedia... I'll rely on my EE degree

For actual physical data supporting it, let's look at the existence of this thread at all. The very fact that people have a hard time telling the difference between flipping polarity and phase inversion is because with no DC offset present they look identical.

you're confusing people's understanding or lack of with what is actually going on. Polarity inversion is not the same thing as Phase. Phase by definition is time related i.e. Sin(wt). magnitude is not. Magnitude is a Scalar and Phase is a Vector.

Polarity inversion is nothing more than multiplying the magnitude by -1 which is a scalar not a vector.

Put simply, take that complex wave graph above, and flip it over vertically. No time changes at all. Show the two waves to a third party and ask them if the second were the result of a polarity change or a 180° phase change, and they, if they were honest, would say that there was no way from just those graphs to tell.

this point is immaterial.

If one required a time factor to execute a phase change, then there would be a horizontal time offset between the two waves when a phase change were executed, and one could see the difference between that and a polarity flip, and the confusion, along with this thread, would be gone.

again, the X axis is time.


If you want to continue stating that Phase differences do no involve time, go ahead but you and your minions will continue to be wrong.

 

[JustAboutReal]

phase/time

If you want to continue stating that Phase differences do no involve time, go ahead but you and your minions will continue to be wrong.

I'm not sure if I entirely understand the points you're trying to make Glen, but I think sonixx is right.

Here's my logic:
1. Frequency is dependent on time.
2. Phase is dependent on Frequency.

Therefore phase is transitively dependent on time as well.

Also your edited wikpedia phase graph showing a phase shift in zero time seems wrong to me because the amplitude is not shifted down. on the whole wave. The wave just starts at a negative amplitude.

Also, If you just move the waveform DOWN the two waveforms would never intersect on the graph.

I don't think that a establishing a new 'resting' voltage (I'm not sure if this is the right word) is a change in phase.

Audio is an AC signal, and if you simply run audio through a transformer you change the resting voltage to 0V. but is that a phase change? it doesn't change the signal in any way other than the arbitrary voltage we use as a middle point.

 

[JustAboutReal]

hard facts

PS - @Glen Do you have any sites other than wikipedia which support your facts? Maybe a different person's explanation would help clear things up?

 

[SouthSIDE Glen]

the X-Axis is Time

I'm not going to argue with you anymore. And please don't wave your degree against my two honors degrees and 30 years in the field, OK? Dubya has a freakin' degree from Yale, yet what he understands about business and law could fit into a shot glass with room left over for a topper. Argue the facts, not dick size.

And besides, sonixx, we all know what's *really* going on here, and it has nothing to do with phase, math, science, sound or electronics engineering. Nor does it take a degree in psychology to understand why you find it impossible to ever agree with me on anything whatsoever, and why you get such a kick out of twisting my words around. I could claim that 2*3 = 6 and you'd find a reason to twist my words around and say that I'm wrong.

That's child's play. You really want to bust my chops? I'll let you in on a secret. You could really mess me up by actually chiming in and agreeing with me once in a while instead of just waiting for what you think is an opening in some thread somewhere down the line to try and knock me down a few pegs. If you actually came in even just once and said, I agree with Glen, he's got it right, 2*3 DOES equal 6. I'd be in an ambulance on the way to the hospital with a blown brain annurism faster than you could hit the "Post Reply" button; and you'd have a forum free of evil ol' me.

Reel, you want references, I already gave you a lead by telling you to look up the Fourier and Hilbert transform functions, just for starters, because those start pointing to the kind of functions required to bust apart complex waves and cause consistant-value phase shift for all frequencies in a complex waveform; none of which require any shifting of the waveform in time.

None of which CAN require a shift in time, exactly because time and frequency ARE related. One cannot shift a complex wave by a simple fixed amount and expect the same change to happen at all frequencies.

It's real tough stuff to get a hold of, I know; it gives me headaches too. But on the other end, you could start with a high school algebra book that explains x/y space, the graphing of functions and what they actually represent, and how simple phase rotation is calculated using the geometry of circles without any introduction of time into the equation whatsoever.

God I hate when these phase/polarity threads come up. I think from now on, I'm just going to answer, "Don't fucking worry about it. No one else understands it either, and it always just winds up in a 5 page thread with zero resolution. Just make your music and be happy."

G.

 

[.guitar]

God I hate when these phase/polarity threads come up. I think from now on, I'm just going to answer, "Don't fucking worry about it. No one else understands it either, and it always just winds up in a 5 page thread with zero resolution. Just make your music and be happy."

G.

I didn't ask for anyone to start arguing...

My main goal was just wondering if there is a way to automate the effect of inverting the polarity...

I have no desire to become an audio engineer, I'm not even that great at math, was just wondering so I could make my music and be happy

 

[The Black Circl]

First let me state that I don't know or care to know what polarity is.

Here is phase explained simply.

Phase is a difference in time - thats it!



One sound wave from the same source reaches the ears faster then another sound wave.

How is this possible?!?!?!?!?!?

Well if you use 2 mics (since we like it to be in stereo and mics are mono, or to get a better tone) and they are placed "incorrectly" then a phasing effect is created!

To avoid mic phasing; mics should either be equiadistant from each other or implement the three to one rule.

3:1 - for every unit a mic is placed from the source the other mic should be exactly 3 units behind the other mic.

To create phasing electronically - insert a device called a phaser into the signal flow, or a device capable of phasing

OR!!!!!! Silde a track slightly off beat in PRO Tools if you got the balls to do it!

PANNING WILL NOT TRUELY CREATE A PHASING EFFECT - This is called stereo imaging!

 

[The Black Circl]

the proper way to write this is sin(wt)

where
w = radian/sec
t = sec

seems to me that your analysis by just stating sin(x) is insufficient. time is the variable that determines the relative phase between two signals for a given frequency w, not gain.

an example of an ideal situation

Two mics

mic 1 (M1), t1 secs from source S0
mic 2 (M2), t2 secs from source S0

subjected to a sine wave with frequency

w (radians/sec)

and are separated by T seconds where T = t2 - t1 seconds

m1 sees the sine wave at t1 seconds
m2 sees the sine wave at t2 seconds

assume at time t0 = -t1 the sine wave leaves the source

The Gain coefficient allowing for air damping respectively is

A1
A2

therefore at any arbitrary time the mics see:

S1 = A1 * sin(w * (t0+t1))
S2 = A2 * sin(w * (t0+t2))

substituting

S2 = A2 * sin(w * (t0 + t1 + T))
S2 = A2 * sin(w * (t0 + t1 + t2 - t1))
S2 = A2 * sin(w * (t0+t2))

Now one can conclude that Gain coefficients influence magnitude and not the time based relationship (phase).

Dude - This has nothing to do with music...

 

[rayc]

Justaboutreal,
PLEASE don't use wiki as the sole source of reference. We don't allow 11 year olds to get away with that downunder. It's a useful source but also an open one so it need backup/corroboration/cross references.
Automated graduated polarity conversion - could you use a phase pedal & manually turn the knob?

 

[Sonixx]

Dude - This has nothing to do with music...

actually it does.

 

[Sonixx]

First let me state that I don't know or care to know what polarity is.

this will serve you well in recording

To avoid mic phasing; mics should either be equiadistant from each other...

the mics should be equidistant from the source. they are equidistant from each other by definition.

 

[Sonixx]

I'm not going to argue with you anymore. And please don't wave your degree against my two honors degrees and 30 years in the field, OK? Dubya has a freakin' degree from Yale, yet what he understands about business and law could fit into a shot glass with room left over for a topper. Argue the facts, not dick size.

And besides, sonixx, we all know what's *really* going on here, and it has nothing to do with phase, math, science, sound or electronics engineering. Nor does it take a degree in psychology to understand why you find it impossible to ever agree with me on anything whatsoever, and why you get such a kick out of twisting my words around. I could claim that 2*3 = 6 and you'd find a reason to twist my words around and say that I'm wrong.

That's child's play. You really want to bust my chops? I'll let you in on a secret. You could really mess me up by actually chiming in and agreeing with me once in a while instead of just waiting for what you think is an opening in some thread somewhere down the line to try and knock me down a few pegs. If you actually came in even just once and said, I agree with Glen, he's got it right, 2*3 DOES equal 6. I'd be in an ambulance on the way to the hospital with a blown brain annurism faster than you could hit the "Post Reply" button; and you'd have a forum free of evil ol' me.

wow, do you really think this deeply about posters and posting on an internet recording forum?

One cannot shift a complex wave by a simple fixed amount and expect the same change to happen at all frequencies.

I agree.

 

[NYMorningstar]

I didn't ask for anyone to start arguing...

My main goal was just wondering if there is a way to automate the effect of inverting the polarity...

I have no desire to become an audio engineer, I'm not even that great at math, was just wondering so I could make my music and be happy

Ain't that the truth. I was talking to my wife about this and she says to me, "Hey, let me tell you how I made your pancakes today. Let's see I used two cups of whole wheat flour but whole wheat flour isn't quite the same as bleached flour because the ...yada yada yada " and then she says to me, " Now do you really care about all that or do you just want them to taste good? "

Well if I needed to know all that before I ate this morning I would of starved and it's the same when it comes to music. If you get caught up in the physics you'll never get anything done.

I don't know if you can automate it but the Vst plugin PhaseBug might do what you are looking for. Its primary function is to shift the phase of an incoming audio signal.

What confuses me is the unlabeled graphs. The x/y axis can be and is used to represent different intangibles and without them being labeled it's confusing to follow. Is it frequency, amplitude, voltage...? Let me leave this behind with the following:

The plotting function of a sin wave - f(t) = A sin 2[pi]ft

To do this we divide up our graph paper horizontally into equal chunks to represent a "time scale", and for each time t we want to plot, we multiply t by 2[pi]f (f=frequency) and look up the sine of the result. That sine value is what gets used for the vertical part of the graph.

When we have two waveforms which have the same shape and frequency but are offset in time, we say they are out of phase by the amount of angle you have to add to the 2[pi]ft term of the first to move them together. In other words the wave defined by sin(2[pi]ft) is out of phase with the wave defined as sin(2[pi]ft+p) by the angle p.



Oh well, back to playing wit me new toy

 

[mixsit]

..To avoid mic phasing; mics should either be equidistant from each other..

Sonixx already covered this one.

...3:1 - for every unit a mic is placed from the source the other mic should be exactly 3 units behind the other mic.

Jeez dude, in your other post you said you had a degree. This bit about 3:1 having anything to do with correcting phase is like a reoccurring scourge of misinformation. It's just flat out wrong.
Here's how to tell.

Put your first mic right up on the source, zero inches. Now do the math. What's the correct 3:1 distance for the second mic?

You said phase is time. Good. And it follows that distance is time.
Time is the frequencies effected.
3:1 inches is not the same time as 3:1 feet. Different distance, different frequencies.

OR!!!!!! Silde a track slightly off beat in PRO Tools if you got the balls to do it!

PANNING WILL NOT TRUELY CREATE A PHASING EFFECT - This is called stereo imaging!

O-tay.

 

[mixsit]

..For example, recording a stereo guitar track with 2 mics...if you invert the "phase" on one, it produces a really strange sound...almost like you can't tell where the guitar is coming from...

Very simply that is the tell tale sound of a source that contains some or most of the same info in both speakers out of polarity with each other.

I'm wondering if there is a way to gradually go from normal "phase" all the way to inverted using automation, or if it is something that can only be flipped completely...or if there is another method to get that effect.

The two things you'll play with here are polarity and time/phase shift.
Flipping polarity is an easy way to try the two different tone shapes (of phase cancellation) when you have two time or distance sources of the same signal. Never will you have 'all frequencies back in phase when there are time differences. But you can have various pleasing sounding happy combinations out of phase.
You can slide one or the other in time and then play, or use a delay -but a lot of delay units won't do that (while in play') without glitching.

 

[The Black Circl]

actually it does.

Actually it doesn't...

Modal theory, intervallatic relationships, complex chord structure, tension and resolve, passing and approach tones, style and technique, scalar theory, blah blah blah has something to do with music

 

[The Black Circl]

this will serve you well in recording



the mics should be equidistant from the source. they are equidistant from each other by definition.

How could it serve me well, what is it use for, or how can it be used?

The thing about equidistant doesn't make sense - I think grammatically

 

[MCI2424]

Maybe going at this from another angle can fix this mess:

About 40 years ago, someone labelled the "polarity switch" on mixing consoles with the wrong word.

Cool, huh?

 

[JustAboutReal]

... lol

How could it serve me well, what is it use for, or how can it be used?

The thing about equidistant doesn't make sense - I think grammatically

What he's saying in, "the mics are equidistant from each other by definition" is that two things are the same distance from each other:

if mic a is 5 feet from mic b... mic b is 5 feet from mic a.

The 3:1 rule is THIS: the rest of you are misinformed lol:
A microphone should be three times as far from THE OTHER MICROPHONES as it is from the source.

Example:
You have 3 mics on a piano. if each mic is 10 inches from the piano, they should be AT LEAST 30 inches away from each other.

Example 2:
You are unhappy with the last recording of the piano so you decide to redo it with only two mics. One mic is 5 inches away from the piano, and the other is 20 inches away from it. The microphones should be 60 inches away from each other.

You should use the larger multiple of three to ensure you don't have microphones all in a row

The way it works:
The signal from the piano itself is 1/3 the distance away at the point you're recording of the distance to the point where the other microphone's signal is coming from. I know that sounds convoluted but stay with me...

the signal strength decreases exponentially, so at 3x the distance you have 1/9 the signal strength. So the signal you're trying to capture with a mic is about 10dB (really it's a bit less) louder than the signal the other mic is recording.

This has been established as enough of a difference to render phase effects... non-problematic (I think I just invented a word there... oh well)

 

[JustAboutReal]

??? what?

Justaboutreal,
PLEASE don't use wiki as the sole source of reference. We don't allow 11 year olds to get away with that downunder. It's a useful source but also an open one so it need backup/corroboration/cross references.
Automated graduated polarity conversion - could you use a phase pedal & manually turn the knob?

I used my brain as the sole source of reference... and then threw in a picture from wikipedia... which was more or less accurate for illustrating the (initially quite simple) answer to the question.

This thread has quickly evolved into a long tangent which contains, by and large, information which will not help the original poster with... well anything really.

instantaneous phase and other complex mathematical algorithms aside... Phase is a time relationship

For any newbie... that should be the answer. I really don't see the point in telling them phase is not a time effect... In 99% of their experiences it will be, and when it's not... who cares they won't even know there was phase to be found anyway (see: linear phase EQ)

also dude... just about any phase pedal is using a time shift to create the effect. Just because the time shift is under 20ms (so it still sounds like one sound) doesn't mean it's not a time effect

 

[The Black Circl]

What he's saying in, "the mics are equidistant from each other by definition" is that two things are the same distance from each other:

if mic a is 5 feet from mic b... mic b is 5 feet from mic a.

The 3:1 rule is THIS: the rest of you are misinformed lol:
A microphone should be three times as far from THE OTHER MICROPHONES as it is from the source.

Example:
You have 3 mics on a piano. if each mic is 10 inches from the piano, they should be AT LEAST 30 inches away from each other.

Example 2:
You are unhappy with the last recording of the piano so you decide to redo it with only two mics. One mic is 5 inches away from the piano, and the other is 20 inches away from it. The microphones should be 60 inches away from each other.

You should use the larger multiple of three to ensure you don't have microphones all in a row

The way it works:
The signal from the piano itself is 1/3 the distance away at the point you're recording of the distance to the point where the other microphone's signal is coming from. I know that sounds convoluted but stay with me...

the signal strength decreases exponentially, so at 3x the distance you have 1/9 the signal strength. So the signal you're trying to capture with a mic is about 10dB (really it's a bit less) louder than the signal the other mic is recording.

This has been established as enough of a difference to render phase effects... non-problematic (I think I just invented a word there... oh well)

First allow me to thank you for clarifying the 3:1 - I really didn't want to.

I understand what your saying and he is saying about the equidistant thing - its obvious and theres no need to state it.

- I was refering to the micing technique known as spatial pairing, coincidence, or near coincidence, or anything simliar to these, particularly thinking of over heads...

Anyways If mic 1 is 5 feet from source, then to avoid phasing, mic 2 should be 5 feet from source - hence equidistant