"Phase inversion" implies that you're taking the negative of the total phase (a frequency domain parameter), which is certainly not being done outside of a time machine. I think we have to keep time domain and frequency domain terms distinct. "Polarity inversion" is simpler to think about in the time domain, as the effect of reversing (e.g.) speaker wires. "
Hey Eric, don't load up too much on the beeeaaah. Once we're through with Frank, we need to pay a visit to John Marks and do a bit more pummeling. 
The March Stereophile arrived today and I was just reading his latest Fifth Element column when I came across this:
"The owner looked pained, but went away to check the setup. Within moments he had powered the system down, and was correcting a relative <b>phase</b> inversion (one speaker hooked up in opposite electrical <b>phase</b> from the other)."
se
The March Stereophile arrived today and I was just reading his latest Fifth Element column when I came across this:
"The owner looked pained, but went away to check the setup. Within moments he had powered the system down, and was correcting a relative <b>phase</b> inversion (one speaker hooked up in opposite electrical <b>phase</b> from the other)."
se
SORRY,JUST PHASED OUT.
Hi,
Phase delay is in the time domain,meaning there will be a lag in time for a certain group ( AKA group delay) of frequencies or all frequencies, shifted somewhat to reach the ear,no?
Yes and while there will be no time delay one half will carry the captured energy positively with repect to the source the other half will carry the negative half.
Listening to the wrong half will not sound correct while the other will.
Hence we are listening to a mirrored image in the latter case.
Yes,and in the English language you talk about phase splitters not polarity splitters be that from a + 180 degrees wavefront or a full + and - 180 degree front.
Neither involves a delay in the time domain.
In a PP amp the output is fed from the phase splitter, one half carrying the positive the other the negative ( + 180 and - 180 degrees).
If perfectly executed neither should have a delay in time with respect to the other half.
Assuming perfect operation the sum is then fed to the speaker terminals giving us the full wavefront again.
In a normal operation this front will be thrown in a forward direction towards the listener from the speaker.
In inverted operation it will directed away from the listener...and this is what makes it detectable to ear as being out of phase with the original message.
Eventually a phase delay will be caused as well before the reflected energy reaches the ear with a completely false message.
On the first occasion the signal is in phase, on the second it is out of phase with the absolute.
Hence the term ablsolute phase, or should that have been absolute polarity?
Naturally...you've all posted while I was typing which is of course completely in phase with the forum spirit.
Cheers,
\Sorry for the time delay...
Hi,
Phase delay is in the time domain,meaning there will be a lag in time for a certain group ( AKA group delay) of frequencies or all frequencies, shifted somewhat to reach the ear,no?
Yes and while there will be no time delay one half will carry the captured energy positively with repect to the source the other half will carry the negative half.
Listening to the wrong half will not sound correct while the other will.
Hence we are listening to a mirrored image in the latter case.
Yes,and in the English language you talk about phase splitters not polarity splitters be that from a + 180 degrees wavefront or a full + and - 180 degree front.
Neither involves a delay in the time domain.
In a PP amp the output is fed from the phase splitter, one half carrying the positive the other the negative ( + 180 and - 180 degrees).
If perfectly executed neither should have a delay in time with respect to the other half.
Assuming perfect operation the sum is then fed to the speaker terminals giving us the full wavefront again.
In a normal operation this front will be thrown in a forward direction towards the listener from the speaker.
In inverted operation it will directed away from the listener...and this is what makes it detectable to ear as being out of phase with the original message.
Eventually a phase delay will be caused as well before the reflected energy reaches the ear with a completely false message.
On the first occasion the signal is in phase, on the second it is out of phase with the absolute.
Hence the term ablsolute phase, or should that have been absolute polarity?
Naturally...you've all posted while I was typing which is of course completely in phase with the forum spirit.
Cheers,
\Sorry for the time delay...
STEREOPHOOLS
Hi,
Great.
There is a relative phase inversion...the goof is : in opposite electrical polarity.
I should never have read those US mags in the first place...now I have all my wires crossed.
Hey...and it's going to be Belgian beer or nothing at all when I'm buying, you hear!
Cheers folk,
Hi,
Great.
There is a relative phase inversion...the goof is : in opposite electrical polarity.
I should never have read those US mags in the first place...now I have all my wires crossed.
Hey...and it's going to be Belgian beer or nothing at all when I'm buying, you hear!
Cheers folk,
Re: SORRY,JUST PHASED OUT.
Well, not so much to reach the ear per se. The important thing is that there is a delay with respect to a certain reference point in time (i.e. along the x axis). Polarity also uses a certain reference point, but on the y axis.
And, there being no time delay, there is no change in phase.
In any language, "phase splitter" is an erroneous term. Polarity splitter would be the more accurate term.
Except that it's not out of phase with the original. It's of opposite polarity.
Well when you're talking about acoustic reflections, then yes, you get into the issue of phase. That's because the reflected wave travels farther than the direct wave, which causes a delay to exist between the two relative to the listening position.
If you're talking about direct versus reflected waves, then you're talking about phase. But if you're comparing the output waveform at the loudspeaker relative to the input waveform at the amplifier, you're talking about polarity, save for any phase shift caused by the amplifier circuitry.
Hehehe. Hey, what can we say. We cheat!
fdegrove said:
Well, not so much to reach the ear per se. The important thing is that there is a delay with respect to a certain reference point in time (i.e. along the x axis). Polarity also uses a certain reference point, but on the y axis.
And, there being no time delay, there is no change in phase.
In any language, "phase splitter" is an erroneous term. Polarity splitter would be the more accurate term.
Except that it's not out of phase with the original. It's of opposite polarity.
Well when you're talking about acoustic reflections, then yes, you get into the issue of phase. That's because the reflected wave travels farther than the direct wave, which causes a delay to exist between the two relative to the listening position.
If you're talking about direct versus reflected waves, then you're talking about phase. But if you're comparing the output waveform at the loudspeaker relative to the input waveform at the amplifier, you're talking about polarity, save for any phase shift caused by the amplifier circuitry.
Naturally...you've all posted while I was typing which is of course completely in phase with the forum spirit.
Hehehe. Hey, what can we say. We cheat!
Re: Re: SORRY,JUST PHASED OUT.
Nope. No phase inversion. Only polarity inversion.
Just for grins, here's what Webster's Ninth Collegiate has to say about "phase" in the context we're talking about here:
<i>The point or stage in a period of uniform circular motion, harmonic motion, or the periodic changes of any magnitude varying according to a simple harmonic law to which the rotation, oscillation, or variation has advanced considered in its relation to a standard position or assumed instant of starting.</i>
I got no problem with that. If Belgian beer is good enough for Hercule Poirot, it's good enough for me.
se
fdegrove said:
Nope. No phase inversion. Only polarity inversion.
Just for grins, here's what Webster's Ninth Collegiate has to say about "phase" in the context we're talking about here:
<i>The point or stage in a period of uniform circular motion, harmonic motion, or the periodic changes of any magnitude varying according to a simple harmonic law to which the rotation, oscillation, or variation has advanced considered in its relation to a standard position or assumed instant of starting.</i>
Hey...and it's going to be Belgian beer or nothing at all when I'm buying, you hear!
I got no problem with that. If Belgian beer is good enough for Hercule Poirot, it's good enough for me.
se
COMPLETEMENT DEPHASE.
Hi.
LOL.
And by the same token one is out of phase with respect to the other.
Phase splitter:
In French: dephaseur.
In Dutch/Flemish: fasedraaier.
In short in any language I know of there always this phase root showing up....
Who's going to pick up the tab for the beer?
Skoll,
Hi.
LOL.
And by the same token one is out of phase with respect to the other.
Phase splitter:
In French: dephaseur.
In Dutch/Flemish: fasedraaier.
In short in any language I know of there always this phase root showing up....
Who's going to pick up the tab for the beer?
Skoll,
You are of course.
Hi,
And I'm not convinced....
So, Eric will be barman and you and me will have a cool Trapist in Brussels.
After a couple of those we'll be out of phase with the world anyway...seeking for a cell polarity change the next day while a time lag will hit us over the head.
Cheers,
Hi,
And I'm not convinced....
So, Eric will be barman and you and me will have a cool Trapist in Brussels.
After a couple of those we'll be out of phase with the world anyway...seeking for a cell polarity change the next day while a time lag will hit us over the head.
Cheers,
Those figures should make it quite clear Steve, and if one adds
a harmonic so the signal becomes assymetric around the time
axis it should be clear that the concepts are not interchangeable
even if ignoring the time shift. I have never thougth very deeply
about this myself before, often thinking of an inversion as a
180 deg. phase shift. I guess we can to some extent blame
the literature for this, the same mistake can be found in well
known books. I just checked my old electronics bible, "Electronic
Circuits: Discrete and Integrated" by Schilling and Belove.
When describing Bode plots they remark that "The negative sign
in T(s) is not included in the Bode plot; thus 180 deg. must be
added to the phase shift indicated by the curve in order to obtain
the Nyquist diagram". I have never bothered much about Nyquist
diagrams, so maybe it is correct, but it can certainly mislead the
reader into thinking of an inversion as a 180 deg. phase shift.
a harmonic so the signal becomes assymetric around the time
axis it should be clear that the concepts are not interchangeable
even if ignoring the time shift. I have never thougth very deeply
about this myself before, often thinking of an inversion as a
180 deg. phase shift. I guess we can to some extent blame
the literature for this, the same mistake can be found in well
known books. I just checked my old electronics bible, "Electronic
Circuits: Discrete and Integrated" by Schilling and Belove.
When describing Bode plots they remark that "The negative sign
in T(s) is not included in the Bode plot; thus 180 deg. must be
added to the phase shift indicated by the curve in order to obtain
the Nyquist diagram". I have never bothered much about Nyquist
diagrams, so maybe it is correct, but it can certainly mislead the
reader into thinking of an inversion as a 180 deg. phase shift.
The equivalence between inversion and a 180 degree phase shift arises in ideal linear system theory. When you are looking at a frequency response (Bode) plot, the mathematics behind assumes that everything is in sinusoidal steady-state.
In other words, all signals are sine waves that go on forever with no beginning or end. Obviously, this isn't true in the real world, and because of this, inversion and a 180 degree phase shift are no longer equivalent.
John
In other words, all signals are sine waves that go on forever with no beginning or end. Obviously, this isn't true in the real world, and because of this, inversion and a 180 degree phase shift are no longer equivalent.
John
JohnG said:
Yes, but even with steady-state signals, phase must be relative
to some reference point, so there is actually a difference
between an inversion and a 180 deg. phase shift, as Steve
pointed out. However, for steady-state signals, two inversions
= one inversion + 180 deg. phase shift = 360 deg phase shift,
which is what we are usually interested in. So, it's often practical
to think of an inversion as a equivalent to a 180 deg. phase
shift, although it is not theoretically correct.
For an ideal sine wave, i.e. one that has no beginning or end, there is no difference between an inversion and a 180 degree phase shift. If you do both operations to such a sine wave and place them on top of each other, there is no difference. Again, this is obviously a mathematical idealization, since there is no proof that time has no beginning or end.
Steve's drawing shows a sine wave with a beginning, so here there is a difference.
John
Steve's drawing shows a sine wave with a beginning, so here there is a difference.
John
JohnG said:
I see, you assume the signal must be a sine wave, while I
take steady-state to mean any periodic signal. For many
types of analyses it doesn't matter much, though, since a
periodic signal is a linear combination of sines.
Edit: Seems I just contradicted the "equation" I gave in my
previous posting. That one doesn't hold for arbitrary
periodic signals either.
Only in the case of a sine wave. For an actual real-world signal (let's take a unit impulse as an example), each delay in the Fourier decomposition will have to be different, a very complicated way of expressing a simple change. In a time domain picture, one merely... reverses the polarity.
I'll have a Ciney Brune, please.
I'll have a Ciney Brune, please.
GOOD BEER INDEED.
Hi,
The pics do show a sinewave, don't they?
All in all this is beside the point, namely phase inversion.
I think I explained it clearly enough, so the case is one of semantics but the result is still a phase inversion?
You guys are going to have a rough time convincing me that my logic is wrong.
Cheers,
\Just opened a bottle of C37.
Hi,
The pics do show a sinewave, don't they?
All in all this is beside the point, namely phase inversion.
I think I explained it clearly enough, so the case is one of semantics but the result is still a phase inversion?
You guys are going to have a rough time convincing me that my logic is wrong.
Cheers,
\Just opened a bottle of C37.
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