The other thing is that academics tend to think in sine waves, a nice idealization which is useful for the sort of circuit analysis that Terman's book deals with. This allows any waveform to be analyzed by looking at linear superpositions of Fourier components, but I can't imagine that Terman and cohort would have called the inversion of (for example) a unit pulse, "reversing the phase" of the pulse.
Personally, I don't listen to too many sine waves.
Personally, I don't listen to too many sine waves.
I wish you lot listened to Steve Eddy and JohnG ages ago......
But it makes a very nice read weekend read
BTW i read somewhere that with precision DC rotory motors there is a slight diffrence in efficiency depending on its polarity. is this correct and can it be correlated to 'speaker drivers ?
But it makes a very nice read weekend read
BTW i read somewhere that with precision DC rotory motors there is a slight diffrence in efficiency depending on its polarity. is this correct and can it be correlated to 'speaker drivers ?
Helix said:
Mmmmm. Can't say whether that's true or not. Though not sure why it would be the case unless it has something to do with the winding arrangement or the magnetics.
Loudspeakers can be somewhat asymmetrical but I'd think that'd have more to do with the mechanical components (i.e. surround and spider).
In any case, can't give you a clear answer on that one. Sorry.
se
AP VII.
Hi,
I never was referring to phase shifts in the first place.
Not just mechanically, most xovers are not symmetrical either.
This is one of the reasons I advise against reversing the speaker leads' polarity for correcting a recording that is out of phase in the first place.
Admittedly it is better than doing nothing at all.
If you want to put it to the test just do some recording of both and compare the results.
Same is true for switching hot and ground at preamp level since these are likely asymmetrical circuits too.
And I could go on till kingdom come with "you lot".
All this academic talk is doing nothing but making people think that by the flick of a switch that just swaps ground for hot and vice versa they can correct for a "polarity" error on the source which is absolutely false.
A MC cartridge is a true balanced source so there you can correct for a "absolute polarity" error by swapping hot for cold.
Not very practical, is it?
So, in conclusion, the entire record industry has it wrong when they say a track is recorded out of phase-no need to tell me how that could have happened,I know how- and loudspeaker designers obviously don't have a clue as to what they talk about either when they reverse polarity on a single unit in a multi-way system the bring it in phase with the rest of the system either.
Right?
Oh, and while I am at it...when you reverse the speaker leads' polarity on one channel in a stereo system and not on the other then one channel is in effect out of phase with respect to other.
Terminology: replace the word phase with polarity here and you won't have the foggiest idea of what's going on anymore.
Yeah,right.
Cheers,
\Just having my wires crossed.
Hi,
I never was referring to phase shifts in the first place.
Not just mechanically, most xovers are not symmetrical either.
This is one of the reasons I advise against reversing the speaker leads' polarity for correcting a recording that is out of phase in the first place.
Admittedly it is better than doing nothing at all.
If you want to put it to the test just do some recording of both and compare the results.
Same is true for switching hot and ground at preamp level since these are likely asymmetrical circuits too.
And I could go on till kingdom come with "you lot".
All this academic talk is doing nothing but making people think that by the flick of a switch that just swaps ground for hot and vice versa they can correct for a "polarity" error on the source which is absolutely false.
A MC cartridge is a true balanced source so there you can correct for a "absolute polarity" error by swapping hot for cold.
Not very practical, is it?
So, in conclusion, the entire record industry has it wrong when they say a track is recorded out of phase-no need to tell me how that could have happened,I know how- and loudspeaker designers obviously don't have a clue as to what they talk about either when they reverse polarity on a single unit in a multi-way system the bring it in phase with the rest of the system either.
Right?
Oh, and while I am at it...when you reverse the speaker leads' polarity on one channel in a stereo system and not on the other then one channel is in effect out of phase with respect to other.
Terminology: replace the word phase with polarity here and you won't have the foggiest idea of what's going on anymore.
Yeah,right.
Cheers,
\Just having my wires crossed.
Re: AP VII.
Then you must not have been talking about phase.
That's a different kind of symmetry from what I was talking about.
An asymmetrical crossover is one which uses either different slopes for the high and low pass functions and/or whose high and low pass functions have different cutoff frequencies. An asymmetrical crossover effects both halves of the signal equally.
What I'm talking about here is where the cone's motion is not symmetrical for a given stimulus. For example, if the cone overshoots more in the forward direction than the rearward direction. That's the asymmetry that I'm talking about. And one which results in distortion.
Apparently you advise against this because you don't understand what an asymmetrical crossover is.
The crossover effects the signal equally for both halves of the signal and has nothing to do with efficacy of reversing the polarity of the speaker leads.
Do some recording of both what?
Again, this has nothing to do with the sort of asymmetry that I'm talking about and it's obvious you're more than a bit confused here.
And if you keep on like this, you'll just be putting your foot further and further into your mouth.
It's absolutely true. It will indeed correct for inverted polarity at the source. Every bit as much as it would by swapping speaker or cartridge leads.
No, manually swapping cartridge leads wouldn't be very practical. It would would be more practical to do it with a switch inside your preamp.
What they should say is that a track doesn't preserve absolute polarity. Or that the polarity of a given track is inverted relative to absolute polarity.
Anything but phase.
In this case, what they do is reverse polarity in a somewhat half-assed attempt to correct for a phase shift (delay) caused by the crossover.
It's an attemp to get the drivers to properly sum acoustically so you get one big lobe instead of two smaller lobes with a suckout between them.
However because music isn't a nice steady state waveform like a sinewave, it doesn't exactly sum the way it would if it were.
Remember previously when I said that if you had two continuous sinewaves that you wouldn't be able to tell if one were simply inverted or shifted in phase by 180 degrees?
Well, that's why continuous sinewaves would sum better acoustically from reversing the polarity of the tweeter than actual music signals do.
No, it's not out of phase. It's of opposite polarity with respect to the other.
You want out of phase? Move your head a little closer to one speaker than the other. That's out of phase. Or keep your head equidistant from both speakers and put a delay line on one of them. That's out of phase.
Simply wiring them up opposite each other? That's simply inverting polarity.
Not having the foggiest idea of what's going on is a condition brought about by not having the foggiest idea of what's going on in the first place.
Sure, if people get in the habit of using inaccurate terminology, it can get a bit confusing when you use accurate terminology. But at least in the end you have the foggiest idea of what's actually going on.
I mean, it did take a while before people got used to thinking in terms of the earth orbiting the sun after they'd believed that the sun orbited the earth for so long. But eventually they got used to it and in the end were the better for it.
se
fdegrove said:
Then you must not have been talking about phase.
That's a different kind of symmetry from what I was talking about.
An asymmetrical crossover is one which uses either different slopes for the high and low pass functions and/or whose high and low pass functions have different cutoff frequencies. An asymmetrical crossover effects both halves of the signal equally.
What I'm talking about here is where the cone's motion is not symmetrical for a given stimulus. For example, if the cone overshoots more in the forward direction than the rearward direction. That's the asymmetry that I'm talking about. And one which results in distortion.
Apparently you advise against this because you don't understand what an asymmetrical crossover is.
The crossover effects the signal equally for both halves of the signal and has nothing to do with efficacy of reversing the polarity of the speaker leads.
Do some recording of both what?
Again, this has nothing to do with the sort of asymmetry that I'm talking about and it's obvious you're more than a bit confused here.
And I could go on till kingdom come with "you lot".
And if you keep on like this, you'll just be putting your foot further and further into your mouth.
It's absolutely true. It will indeed correct for inverted polarity at the source. Every bit as much as it would by swapping speaker or cartridge leads.
No, manually swapping cartridge leads wouldn't be very practical. It would would be more practical to do it with a switch inside your preamp.
What they should say is that a track doesn't preserve absolute polarity. Or that the polarity of a given track is inverted relative to absolute polarity.
Anything but phase.
In this case, what they do is reverse polarity in a somewhat half-assed attempt to correct for a phase shift (delay) caused by the crossover.
It's an attemp to get the drivers to properly sum acoustically so you get one big lobe instead of two smaller lobes with a suckout between them.
However because music isn't a nice steady state waveform like a sinewave, it doesn't exactly sum the way it would if it were.
Remember previously when I said that if you had two continuous sinewaves that you wouldn't be able to tell if one were simply inverted or shifted in phase by 180 degrees?
Well, that's why continuous sinewaves would sum better acoustically from reversing the polarity of the tweeter than actual music signals do.
No, it's not out of phase. It's of opposite polarity with respect to the other.
You want out of phase? Move your head a little closer to one speaker than the other. That's out of phase. Or keep your head equidistant from both speakers and put a delay line on one of them. That's out of phase.
Simply wiring them up opposite each other? That's simply inverting polarity.
Not having the foggiest idea of what's going on is a condition brought about by not having the foggiest idea of what's going on in the first place.
Sure, if people get in the habit of using inaccurate terminology, it can get a bit confusing when you use accurate terminology. But at least in the end you have the foggiest idea of what's actually going on.
I mean, it did take a while before people got used to thinking in terms of the earth orbiting the sun after they'd believed that the sun orbited the earth for so long. But eventually they got used to it and in the end were the better for it.
se
Reolarity Is The Word .
Hi Eric,
It seems you can't wait.
I don't know about you but I can hear differences (quite audibles ones) as to where in the chain the polarity is reversed.
Hi Steve,
I realise that fully and it seems you don't want to understand that most x-over are directive too.
So if anyone has difficulty hearing polarity reversal it may be a good idea to listen to a x-overless speaker.
FWIW putting your x-over components in the send or return path does make for an audible difference too.
Sorry to disagree but you'll do more than just reversing polarity if you just use a switch to reverse polarity.
In fact you detailed the reasoning against it already,partially that is.
From what I read at the beginning of this thread you can't be bothered with it so I suppose you have never really made an effort as to the audible differences when executed in SE home equipment.
So, if we want to carry this any further I would like to hear from anyone how polarity reversal is best achieved in this context.
P.S.Notice how quickly I adopt to new (to me) terminology.
Cheers,
olarity Is The Word .Hi Eric,
It seems you can't wait.
I don't know about you but I can hear differences (quite audibles ones) as to where in the chain the polarity is reversed.
Hi Steve,
I realise that fully and it seems you don't want to understand that most x-over are directive too.
So if anyone has difficulty hearing polarity reversal it may be a good idea to listen to a x-overless speaker.
FWIW putting your x-over components in the send or return path does make for an audible difference too.
Sorry to disagree but you'll do more than just reversing polarity if you just use a switch to reverse polarity.
In fact you detailed the reasoning against it already,partially that is.
From what I read at the beginning of this thread you can't be bothered with it so I suppose you have never really made an effort as to the audible differences when executed in SE home equipment.
So, if we want to carry this any further I would like to hear from anyone how polarity reversal is best achieved in this context.
P.S.Notice how quickly I adopt to new (to me) terminology.
Cheers,
Re: Reolarity Is The Word .
I'm more than willing to understand. Now how 'bout explaining it? What, exactly, makes a crossover "directive"? Are you speaking in the same sense as Eric when he says that wire is "directional" or do you mean something else?
Send or return path? Uh, Frank, audio isn't DC. It's AC. Half the time your send is return and your return is send.
You originally argued that it simply wouldn't result in a reversal of polarity. Let me refresh your memory:
<i><b>In that case you could argue that a simple inversion of the positive lead and negative lead of a preamp coaxwire would give a 180 degree inversion. We all know that that does not work in a single ended topology, don't we.</i></b>
Can't be bothered with what? The issue wasn't about audible differences, the issue was whether it would result in reversing polarity. That's the only criteria you gave in your argument.
Read it again:
<i><b>In that case you could argue that a simple inversion of the positive lead and negative lead of a preamp coaxwire would give a 180 degree inversion.</i></b>
Once again, it does indeed give you a reversal of polarity.
It being less than ideal with regard to being more susceptible ground loop and other noise is a whole other matter.
The issue as YOU STATED IT, had nothing to do with it being the best way to achieve it. Your argument was that it simply wouldn't result in polarity inversion at all.
Once again:
<i><b>In that case you could argue that a simple inversion of the positive lead and negative lead of a preamp coaxwire would give a 180 degree inversion.</i></b>
Yes, I can argue it because it absolutely DOES result in polarity inversion.
Whether that's the BEST way to do it is again, a whole other matter.
se
olarity Is The Word .fdegrove said:
I'm more than willing to understand. Now how 'bout explaining it? What, exactly, makes a crossover "directive"? Are you speaking in the same sense as Eric when he says that wire is "directional" or do you mean something else?
Send or return path? Uh, Frank, audio isn't DC. It's AC. Half the time your send is return and your return is send.
You originally argued that it simply wouldn't result in a reversal of polarity. Let me refresh your memory:
<i><b>In that case you could argue that a simple inversion of the positive lead and negative lead of a preamp coaxwire would give a 180 degree inversion. We all know that that does not work in a single ended topology, don't we.</i></b>
Can't be bothered with what? The issue wasn't about audible differences, the issue was whether it would result in reversing polarity. That's the only criteria you gave in your argument.
Read it again:
<i><b>In that case you could argue that a simple inversion of the positive lead and negative lead of a preamp coaxwire would give a 180 degree inversion.</i></b>
Once again, it does indeed give you a reversal of polarity.
It being less than ideal with regard to being more susceptible ground loop and other noise is a whole other matter.
The issue as YOU STATED IT, had nothing to do with it being the best way to achieve it. Your argument was that it simply wouldn't result in polarity inversion at all.
Once again:
<i><b>In that case you could argue that a simple inversion of the positive lead and negative lead of a preamp coaxwire would give a 180 degree inversion.</i></b>
Yes, I can argue it because it absolutely DOES result in polarity inversion.
Whether that's the BEST way to do it is again, a whole other matter.
se
POLAR BEARS.
Hi,
Just kidding....
Yes Steve, I know that too and while you assumed I meant to say that it wouldn't work at all I meant that you just can't implement it like that.
Which is precisely what you have explained already later on.
So...if we agree on that...it may be of interest to other members what exactly are the better ways of doing the polarity inversion.
I think we both agree it is best done at preamp level or do you hold a different view on that?
Sorry, I meant directional indeed.
Yes, again I am aware of that as well.
It does not make any sense and the only possible explanation I can think of is the asymmetry of the speaker itself.
It is however a bit of a topic on its' own.
Cheers,
Hi,
Just kidding....
Yes Steve, I know that too and while you assumed I meant to say that it wouldn't work at all I meant that you just can't implement it like that.
Which is precisely what you have explained already later on.
So...if we agree on that...it may be of interest to other members what exactly are the better ways of doing the polarity inversion.
I think we both agree it is best done at preamp level or do you hold a different view on that?
Sorry, I meant directional indeed.
Yes, again I am aware of that as well.
It does not make any sense and the only possible explanation I can think of is the asymmetry of the speaker itself.
It is however a bit of a topic on its' own.
Cheers,
A radio guy was telling me about a phase sensitive detector (a 'block' from the classic text book PLL discriminator block diagrams) and showing the output of said PSD for two signals which are at 'anti-phase' to each other, then he said 'or in other words a 180 degree phase difference'.
Well then for some reason every body who say 180 degree phase change or similar I immediately think of Steve Eddy and Mrfeedback absolute phase argument.
now i am thinking
anti-phase = absolute polarity inversion
e.g the ouput of inverting amp is in anti-phase of the input.... or alternativly the absolute polarity of the output signal is inverted with respect to the input
Well then for some reason every body who say 180 degree phase change or similar I immediately think of Steve Eddy and Mrfeedback absolute phase argument.
now i am thinking
anti-phase = absolute polarity inversion
e.g the ouput of inverting amp is in anti-phase of the input.... or alternativly the absolute polarity of the output signal is inverted with respect to the input
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.