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[Art Welter]

Probably.No.. phase is phase and polarity is polarity. Neither, Polarity is either Positive (correct) or Negative (opposite) . The 180' phase shift only resembles opposite polarity for sine waves, for complex waveforms phase shift has little meaning.   Delay time will be insignificant in the context of audio frequency phase shift.

JR

JR,

You beat me to all the salient points, but since I already wrote up a bit more explanation to David Allred's questions, here goes.

Phase and polarity are distinctly different, a polarity swap electrically reverses all frequencies 180 degrees, which if a speaker had flat phase response, would cause total cancellation between two reversed polarity speakers of an infinitely small size located next to each other.

The vast majority of powered speakers on a stick are nothing of the sort, they are of bass reflex design, which takes the  inverted phase of the back movement of the woofer's cone which resonates at the box frequency (Fb) and emerges 360 degrees later (phase inversion) to combine in phase with the forward movement of the cone. The phase inversion only occurs over a limited bandwidth, or it would cause cancellation. Even though the bass produced by the bass reflex cabinet relies on a phase inversion, and the crossovers used may also separate it in time/phase from the upper transients (the "click" of a kick) by anywhere from 90 to over 720 degrees, our hearing still identifies the "kick" as a single event.

Regarding length of cable, the difference between 186,282 miles per second and 1130 feet per second is long enough to make cable distance make no audible difference in phase even at 10,000 feet. That said, many powered speakers use DSP that has anywhere from half to several milliseconds delay, the phase consequence of those speakers mixed with an analog system which has almost zero latency, or DSP systems can have a large effect, there is no "correct" polarity once DSP latency is considered, other than when using identical systems together, keep it the same.

Art

[Steve M Smith]

Because I'm a sad case....

Speed of electricity is about 5nS per metre so if you have a 10 metre difference in your speaker cables, that's a 50nS delay from the speaker with the long cable.

Speed of sound through air is about 340mS so in 50nS, 

Distance travelled = (340 x 50) / 1,000,000,000 = 0.000017 metres

Or the equivalent of having your speaker cabinet 0.017mm too far back!!


Steve.

[Ivan Beaver]

Me brain fart.  Me clarify.

1) "Mute" should read "moot".

3) "Correct" as in moving out when +v is applied.  For example...
a - signal recorded "in phase"
b - output at play devise - in phase
c - connection cable mis-wired so signal is out of phase at amp input
d - signal in amp - out of phase
e - amplified signal exiting amp - out of phase
f - speaker cable connections switched + to -, - to +

Is the cone movement direction correct to the intent of the recording?

In the context of this discussion, are phase and polarity referring to the same thing?

Am I wrong in saying that phase is the result, but polarity is the cause... since wiring is the topic?

Which is correct? 
Polarity can only be 0 deg & 180 deg.
or
Polarity is any 180 deg differential.  (10 & 190, 90 & 270, etc)

Last stupid question:
If a signal is sent through 2 disproportionately lengthed cables to an amp / speakers, will the output be produced out of phase to each other?  To what extent?  1' vs 100', 1' vs 1000', 1' vs 10,000'?

I love the smell of minutia in the morning.
Thanks for all the discussion.

You are talking about polarity.  Phase is COMPLETELY different

For example

You can have a speaker that in polarity and completely out of phase-depending on the freq looked at.

Just overlay 2 sine waves  of different freq-say an octave apart.  so that they "start" together (say rising)  They are "in polarity".

Now just look at different points along the overlay.  You will see that they are "in phase" at some points and completely "out of phase" at other points.

But they are always "in polarity".

The term phase is used wrongly more times than it is used correctly.

You have noticed there are several members of the "polarity police" here-so it is wise to listen to them.

[David Allred]

JR, Art, Steve, Ivan,
All your answers are what I was looking for.  Minutia though it may be, it yields a degree of confidence.
Thanks.

[Ivan Beaver]

Which is correct? 
Polarity can only be 0 deg & 180 deg.
or
Polarity is any 180 deg differential.  (10 & 190, 90 & 270, etc)

Polarity is in or out, not 0 or 180.  You simply changing from one relative relationship to another.  Since the incoming signal could be of any polarity-how do you know which is 0 or 180.  All you are doing is changing the relationship of the incoming signal to the circuit that it is hooked to.

Phase and be any number (out to a hundred decimal places or more if you want) up to  millions of numbers.

It is not some "standard" number.

0 and 360 share the same value in terms of level-but are different places in time.

A phase "number" simply means that is a certain place along the "timeline" to another place along the timeline.

65° phase for one freq is at a completely different time than 65° of another freq-yet both freq would be "in time" no matter the polarity.

Absolute polarity is something that is highly debated.

And how do you know the signal getting to the "device in question" is in polarity?  It has probably gone through hundreds of different stages before you get it (in the case of a recording)-a live mic not so much-but could still go through the mic and several cables (mic cable-snake-patchbay-patch cables etc) none of which are capable of changing the "phase" but all are capable of changing the polarity.

[Jonathan Johnson]

Polarity is in or out, not 0 or 180.  You simply changing from one relative relationship to another.  Since the incoming signal could be of any polarity-how do you know which is 0 or 180.  All you are doing is changing the relationship of the incoming signal to the circuit that it is hooked to.

Phase and be any number (out to a hundred decimal places or more if you want) up to  millions of numbers.

It is not some "standard" number.

0 and 360 share the same value in terms of level-but are different places in time.

A phase "number" simply means that is a certain place along the "timeline" to another place along the timeline.

65° phase for one freq is at a completely different time than 65° of another freq-yet both freq would be "in time" no matter the polarity.

Absolute polarity is something that is highly debated.

And how do you know the signal getting to the "device in question" is in polarity?  It has probably gone through hundreds of different stages before you get it (in the case of a recording)-a live mic not so much-but could still go through the mic and several cables (mic cable-snake-patchbay-patch cables etc) none of which are capable of changing the "phase" but all are capable of changing the polarity.

Thank you, Ivan.

The term phase is ONLY valid when applied to a consistent waveform (such as a sine wave or the tone of a continuous note on an accordion), and phase is measured as an angle referenced to one complete cycle of the wave form represented as a circle, 360 degrees.

Most audio engineers and technicians should banish the word phase from their vocabularies, as it is almost always misused. The proper terms to use are polarity and delay.

A delay of 1/120th of a second will result in a 60 Hz tone being 180 degrees out of phase with a non-delayed 60 Hz tone. But that same delay would result in a 120 Hz tone being in-phase (and a 121 Hz tone being about 3 degrees out of phase -- maybe, my head-math is probably wrong but the concept is good). But for all three waveforms, there is a consistent delay of 1/120th of a second.

When you are reinforcing a live performance, if you are running a pure analog system and your loudspeakers are 10 feet closer to the audience than the performer, the reproduced sound from the loudspeaker will arrive at the listener's ears about 8 ms before the direct sound from the performer. It makes ABSOLUTELY NO SENSE to say that the sound is 8 ms out of phase, since phase can only be measured as an angle, and only for a single cycle. For one frequency, the phase angle will be different than another frequency. The proper way to describe this is that the direct sound is DELAYED by 8 ms relative to the reproduced sound.

Here's where it gets important. If you have a live drum, miced and fed into a sound system with a loudspeaker some distance in front of the drum, you could conceivably have a loudspeaker wired with reverse polarity and still have constructive interference. If the wave from the drumhead matches the wave from the loudspeaker as the waves meet, it will be constructive. If, due to the delay, the wave from the speaker is 180 degrees out-of-phase (we can use the term phase here ONLY because we are dealing with a single wave, not a complex and changing waveform) -- or one half of a cycle -- it will cancel.

A waveform that is reversed polarity but is not subject to delay is not 180 degrees out of phase. It actually is perfectly in-phase. It is reversed polarity, and will cancel a matching waveform of positive polarity.

[Andrew Hollis]

. . . the TRS's polarity (tip = + vs -) is unknown, does the signal flow matter? The powered speaker in question is a Yorkville C120P.

Only unknown to those that do not RTFM.

Balancing code is; Tip= (+) 0° phase, Ring= (-) 180° phase, and Sleeve=Ground.

[Ivan Beaver]

Here's where it gets important. If you have a live drum, miced and fed into a sound system with a loudspeaker some distance in front of the drum, you could conceivably have a loudspeaker wired with reverse polarity and still have constructive interference. If the wave from the drumhead matches the wave from the loudspeaker as the waves meet, it will be constructive. If, due to the delay, the wave from the speaker is 180 degrees out-of-phase (we can use the term phase here ONLY because we are dealing with a single wave, not a complex and changing waveform) it will cancel.

IF the drum produced a single freq.  But with overtones and "other sounds" some freq could be in phase and other out of phase at the same seating location.

HOWEVER move 10' in any direction and everything has changed.

The idea of delaying mains to the back line works in one seating position-especially since the back line and PA are not in "line" with each other.  So whatever delay is set, will be wrong for other positions.

And if the PA is a lot louder than the backline-then there may be little "influence" from one to the other.

[John Roberts {JR}]

IF the drum produced a single freq.  But with overtones and "other sounds" some freq could be in phase and other out of phase at the same seating location.

Yes most drums make complex waveforms, but the bass/kick drum will voice predominantly at one note. In a small room where the acoustic output from the drum is close to the PA output in that frequency range, there could be an audible interference that changes with polarity.

HOWEVER move 10' in any direction and everything has changed.

The idea of delaying mains to the back line works in one seating position-especially since the back line and PA are not in "line" with each other.  So whatever delay is set, will be wrong for other positions.

There could be some benefit to aligning arrival time from mostly HF percussive sounds (like snare hits) from the drum kit and same sounds in PA, but as Ivan noted the stage/room geometry can limit the benefit and optimal tuning of this.

And if the PA is a lot louder than the backline-then there may be little "influence" from one to the other.

Ding ding ding... Yes, for constructive or destructive interference the signals need to be at similar levels. Percussive timing issues are not the same mechanism so harder to mask with PA SPL.

JR

[David Allred]

Only unknown to those that do not RTFM.

How did I not see that on the sheet?  Thanks.
So is Yorkville using the term correctly when they say, "Balancing code is; Tip= (+) 0° phase, Ring= (-) 180° phase, and Sleeve=Ground."?

[ProSoundWeb Community]