In most systems, I wonder whether any attention is even paid to the polarity of the connection from the amplifier output terminals to the speakers? (The same for both, obviously, but what about the absolute polarity?)
Is there a universal convention among speaker manufacturers about denoting which terminal needs to go positive for an outward movement of the cone? (Again, obviously, the same for all speakers of a given model made by that manufacturer, but what about different speaker types, and different manufacturers?)
I've never paid attention to this because I'm sure I would not be able to hear the difference of an absolute polarity change anyway. I am doubtful that anyone can genuinely hear a difference (and prove it by means of blind testing), but then I am a natural skeptic. But I am still curious as to whether speaker manufacturers follow a universal convention that indicates the absolute polarity of the speaker terminals.
Anyway, as was said on this thread a few years ago, if one wants to experiment with the effect of an absolute polarity reversal, an easy way is to flip the two wires on each of the speakers.
Is there a universal convention among speaker manufacturers about denoting which terminal needs to go positive for an outward movement of the cone? (Again, obviously, the same for all speakers of a given model made by that manufacturer, but what about different speaker types, and different manufacturers?)
I've never paid attention to this because I'm sure I would not be able to hear the difference of an absolute polarity change anyway. I am doubtful that anyone can genuinely hear a difference (and prove it by means of blind testing), but then I am a natural skeptic. But I am still curious as to whether speaker manufacturers follow a universal convention that indicates the absolute polarity of the speaker terminals.
Anyway, as was said on this thread a few years ago, if one wants to experiment with the effect of an absolute polarity reversal, an easy way is to flip the two wires on each of the speakers.
Last edited:
"Standard polarity is that the woofer cone moves outward when a positive voltage is applied to the positive (red) speaker terminal."
Thanks for that. It had never occurred to me before that there might actually be a convention that is followed. I checked with some speakers of mine, and indeed they all follow your rule.
Thanks for that. It had never occurred to me before that there might actually be a convention that is followed. I checked with some speakers of mine, and indeed they all follow your rule.
Also there is a difference between in phase and in positive phase. In phase just means both speakers go in or out at the same time. In positive phase means they both go out when a positive signal is applied. The difference is that when a speaker is moving outward it is compressing the air in the room, inward creates a lower pressure. There is no limit to how much the air can be compressed but a vacuum can only go to zero pressure. A system that is in correct absolute phase usually has more impact or slam than one in inverted phase. Pressure waves travel better than vacuum waves. The net lesson is listen to something with sharp impacts on your system then flip both speaker plus and minus connections and listen. The correct way will have more impact. On a solid state system you can use a small 1.5v battery on the input to see which way the woofers move when plus on the battery is connected to plus on the input rca. Tube amps don’t do DC so it doesn’t work with them.
All the way from which side of the strike of the bass drum and which side the mic is on . . .
All the way from the microphone connections . . .
All the mic transformers, preamps, on-site recorder, studio editing, recording machine such as CD recorder or LP cutting head . . .
And then all the way through the playback system . . .
What you can say about absolute phase (compression or rarefaction), is that there are too many places that may not have been paid attention to, in order to be sure what the absolute phase is.
Standards are such a wonderful thing, everyone has his own.
1.Look at the bass drum signal at your speaker terminals
2. Then look at the trumpet signal at your speaker terminals
3. Then look at other instruments signals at your speaker terminals
Compare that to your own microphone and scope for which you have tested them for absolute phase.
You may find that in the 'professional' recording, and then that is sent through your playback system, some of number 1, 2, and 3 are in the correct absolute phase, and some of 1, 2, and 3 are not in the correct absolute phase.
A lot of musical instruments have waveforms that are Not symmetrical, which allows you do do the testing and see for yourselves.
I first looked at such waveforms, and absolute phase in high school in the early 60s.
The problem with maintaining absolute phase, with each and every microphone, and including all the way through the recording process, and then your playback system, has never gone away.
YPMV (Your Phase May Vary).
All the way from the microphone connections . . .
All the mic transformers, preamps, on-site recorder, studio editing, recording machine such as CD recorder or LP cutting head . . .
And then all the way through the playback system . . .
What you can say about absolute phase (compression or rarefaction), is that there are too many places that may not have been paid attention to, in order to be sure what the absolute phase is.
Standards are such a wonderful thing, everyone has his own.
1.Look at the bass drum signal at your speaker terminals
2. Then look at the trumpet signal at your speaker terminals
3. Then look at other instruments signals at your speaker terminals
Compare that to your own microphone and scope for which you have tested them for absolute phase.
You may find that in the 'professional' recording, and then that is sent through your playback system, some of number 1, 2, and 3 are in the correct absolute phase, and some of 1, 2, and 3 are not in the correct absolute phase.
A lot of musical instruments have waveforms that are Not symmetrical, which allows you do do the testing and see for yourselves.
I first looked at such waveforms, and absolute phase in high school in the early 60s.
The problem with maintaining absolute phase, with each and every microphone, and including all the way through the recording process, and then your playback system, has never gone away.
YPMV (Your Phase May Vary).
Last edited:
To reproduce the recording faithfully positive must be positive and negative negative. This does not mean the material was recorded properly but to play it back as it was recorded warts and all the system must be in correct absolute phase. This assures you will hear it as the engineer mixed and mastered it. If the engineer did a good job you will hear it as it was meant to be. If he recorded the kick from the wrong side you will hear that too because you are in correct absolute phase.
Yes. I think it was understood in all of the present thread that it was the absolute polarity that was under discussion, and not merely getting the relative phase of the left and right channels correct, which is an easily heard thing, and very simple to get right.
That is true, but one does need to keep in mind that the change in air pressure in even the loudest soundwaves one is likely to encounter in audio is a tiny fraction of the ambient air pressure. (Of order 0.02% or so at the very most.) So any nonlinearity in the soundwave transmission in air due to rarefaction versus compression asymmetry you mention will probably be negligible.
Much more significant, probably, are asymmetries (distortions) associated with the response of the speaker cone itself, possible distortions in the amplifier (especially if it is a highly distorting one like an SET playing at high volume), and even asymmetries in the response of the ear itself.
Since some musical instruments certainly produce asymmetric waveforms, it would indeed be conceivable that the absolute phasing of some of the aforementioned sources of asymmetric distortion, relative to that of the original sound source, could be noticeable.
Let the recording engineer pick where to locate each and every microphone.
After all the recording process is done, and all the playback process is done, then . . .
Any instrument note or percussive transient that starts with a compression of air (from where the microphone was located) . . .
Should start with a compression of air from your loudspeaker to where you are sitting.
and . . .
Any instrument note or percussive transient that starts with a rarefaction of air (from where the microphone was located) . . .
Should start with a rarefaction of air from your loudspeaker to where you are sitting.
Anything other than that is Not Absolute Phase.
This is a total complete system of reproducing "what" the microphone "heard".
Doctor it as much as you want after that for sound effect, and destroy Absolute Phase.
Just my considered opinion.
One more problem:
I had 2 tweeters of one model, and two tweeters of another model.
The first model pair had one of them that was mis-marked for phase, probably the ceramic magnet was installed upside down.
The second model pair had one of them that was mis-marked for phase, probably the ceramic magnet was installed upside down.
Because I was so unlucky, I will not go to Las Vegas.
But I was lucky to find the problem, so maybe I am lucky, I think I will go to Las Vegas.
After all the recording process is done, and all the playback process is done, then . . .
Any instrument note or percussive transient that starts with a compression of air (from where the microphone was located) . . .
Should start with a compression of air from your loudspeaker to where you are sitting.
and . . .
Any instrument note or percussive transient that starts with a rarefaction of air (from where the microphone was located) . . .
Should start with a rarefaction of air from your loudspeaker to where you are sitting.
Anything other than that is Not Absolute Phase.
This is a total complete system of reproducing "what" the microphone "heard".
Doctor it as much as you want after that for sound effect, and destroy Absolute Phase.
Just my considered opinion.
One more problem:
I had 2 tweeters of one model, and two tweeters of another model.
The first model pair had one of them that was mis-marked for phase, probably the ceramic magnet was installed upside down.
The second model pair had one of them that was mis-marked for phase, probably the ceramic magnet was installed upside down.
Because I was so unlucky, I will not go to Las Vegas.
But I was lucky to find the problem, so maybe I am lucky, I think I will go to Las Vegas.
Last edited:
Some recordings have some instruments recorded in Absolute phase, and some instruments on the same recording might be recorded in the Opposite of Absolute phase.
That is what I am saying.
Two microphones, 2 microphone elements, 2 internal matching transformers;
2 XLR cables, 2 preamp input transformers, and . . .
Poor quality control, and no testing of phase = 10 possible places where one signal is Not in absolute phase.
Then there are all the other places to go wrong all the way to your loudspeakers.
It might sound great to the recording engineer in the initial recording studio, but that does not make it absolute phase.
Unless every part along the way was tested individually, or at least all those parts were tested as a complete system.
That is what I am saying.
And . . .
All the other parts the rest of the way through the recording, playback, amplifiers, and loudspeakers can either preserve, or cancel the absolute phase of the instrument.
That is what I am saying.
Two microphones, 2 microphone elements, 2 internal matching transformers;
2 XLR cables, 2 preamp input transformers, and . . .
Poor quality control, and no testing of phase = 10 possible places where one signal is Not in absolute phase.
Then there are all the other places to go wrong all the way to your loudspeakers.
It might sound great to the recording engineer in the initial recording studio, but that does not make it absolute phase.
Unless every part along the way was tested individually, or at least all those parts were tested as a complete system.
That is what I am saying.
And . . .
All the other parts the rest of the way through the recording, playback, amplifiers, and loudspeakers can either preserve, or cancel the absolute phase of the instrument.
Last edited:
In every recording studio I have wired and every one I’ve been in all the mics, xlrs, patchbays, inputs, etc are all wired the same polarity and all have been tested as such before they are put in service. Recording the kick drum from one side or the other does not make the signal wiring out of phase, it makes the sound different but still recorded in phase with regard to all other mics etc.. if the xlr was wired backwards that would actually make the signal out of phase relative to everything else. So assuming the source is to be played back as recorded your system at home must be in absolute phase to produce the sound as intended by the engineer.
I suspect almost all studios and almost all production houses do check the Relative phase of the signals, all the way from the microphones to the CD or LP.
What might not get checked by some studios and production houses, is the Absolute phase.
The different sides of the bass drum was a simple example (struck side, or the other side).
What is not known by many is the asymmetrical shape of the french horn, trumpet, trombone, and so many other instruments.
It is important to maintain the direction of those signal asymmetry versus compression and rarefaction . . . If you want to actually preserve them to be the same as it was at the site of the original music performance.
But then, you have to discuss or decide if the absolute preservation of the original compressions and original rarefactions can be heard, versus not preserving them (does it make any difference).
Does it matter if the chicken (compression) or the egg (rarefaction) comes first.
I do not know.
But when you consider that our ears have second harmonic distortion (due to asymmetry), it seems like this might be an area of study (if it has not been done before).
If it has already been done, there should be some papers or books on the effects or non-effects, related to whether the effect can be audibly detected.
What might not get checked by some studios and production houses, is the Absolute phase.
The different sides of the bass drum was a simple example (struck side, or the other side).
What is not known by many is the asymmetrical shape of the french horn, trumpet, trombone, and so many other instruments.
It is important to maintain the direction of those signal asymmetry versus compression and rarefaction . . . If you want to actually preserve them to be the same as it was at the site of the original music performance.
But then, you have to discuss or decide if the absolute preservation of the original compressions and original rarefactions can be heard, versus not preserving them (does it make any difference).
Does it matter if the chicken (compression) or the egg (rarefaction) comes first.
I do not know.
But when you consider that our ears have second harmonic distortion (due to asymmetry), it seems like this might be an area of study (if it has not been done before).
If it has already been done, there should be some papers or books on the effects or non-effects, related to whether the effect can be audibly detected.
Last edited:
The placement of the mic on one side or the other of the drum does not change the phase of the mic! The mic is still in phase with all other mics however the sound being received is different from on side to the other. The engineer or producer wanted that sound. Since all mics and associated equipment are wired the same way anything recorded by any of them will be in absolute phase. Problems with phase occur when the source is played back at home where many preamps and amps invert the phase from input to output. If you’re lucky either both are inverting or non inverting not one of each. This is why many high end units say if they are inverting or non inverting in their specs. My old Mac MX110 has an invert switch to accommodate such imbalances. If it didn’t matter they wouldn’t put it on the front panel.
"The placement of the mic on one side or the other of the drum does not change the phase of the mic! The mic is still in phase with all other mics however the sound being received is different from on side to the other. The engineer or producer wanted that sound. Since all mics and associated equipment are wired the same way anything recorded by any of them will be in absolute phase. "
This brings to mind some interesting questions about what the goal of the sound engineer should really be. It would seem a reasonable aim should be to reproduce, as closely as possible, what a person (call him an observer) would actually be hearing if they were present at the performance. That might suggest that the microphones (with absolute phasing in the whole audio path carefully preserved) should all be pointing in the directions outwards from the location of the notional "observer."
Since sound waves in air travel quite slowly (about 1000ft per second), it would also suggest that delays in the audio signals from the various microphones distributed around the concert hall should also be introduced, so that the sounds from the microphones would all be synchronised to when they would actually reach the notional observer. (The necessary delay would be about 1 millisecond per foot of separation between the notional observer and where the remote microphone is actually located.)
I wonder if the idea of delaying the microphone signals so that they are all synchronised to a specific point location in the concert hall has ever been experimented with?
This brings to mind some interesting questions about what the goal of the sound engineer should really be. It would seem a reasonable aim should be to reproduce, as closely as possible, what a person (call him an observer) would actually be hearing if they were present at the performance. That might suggest that the microphones (with absolute phasing in the whole audio path carefully preserved) should all be pointing in the directions outwards from the location of the notional "observer."
Since sound waves in air travel quite slowly (about 1000ft per second), it would also suggest that delays in the audio signals from the various microphones distributed around the concert hall should also be introduced, so that the sounds from the microphones would all be synchronised to when they would actually reach the notional observer. (The necessary delay would be about 1 millisecond per foot of separation between the notional observer and where the remote microphone is actually located.)
I wonder if the idea of delaying the microphone signals so that they are all synchronised to a specific point location in the concert hall has ever been experimented with?
"It is called binaural recording. Two mics in the location of ears on a dummy head."
Right. But my understanding is that this is not the typical way a concert would be professionally recorded?
I have the impression that it is more common to have quite a few microphones, strategically placed around the various musical instruments. Is that right? In which case, unless appropriate time delays are introduced for the different microphone signals from different locations, the composite signal that is eventually produced from the mixing will have relative timing differences that would not correspond to what any one person present at the performance would ever hear.
On the face of it, in the case of a large orchestra, I could imagine these might be sufficient to be noticeable. Which is why I was curious to know whether there has ever been any investigation of whether compensating time delays might make an audible difference.
Right. But my understanding is that this is not the typical way a concert would be professionally recorded?
I have the impression that it is more common to have quite a few microphones, strategically placed around the various musical instruments. Is that right? In which case, unless appropriate time delays are introduced for the different microphone signals from different locations, the composite signal that is eventually produced from the mixing will have relative timing differences that would not correspond to what any one person present at the performance would ever hear.
On the face of it, in the case of a large orchestra, I could imagine these might be sufficient to be noticeable. Which is why I was curious to know whether there has ever been any investigation of whether compensating time delays might make an audible difference.
To check polarity of line level devices and power amps, I have long used a sawtooth wave. (not triangle) Being an asymmetric waveform, it's very easy to see on an o'scope if the polarity is correct. Where is the leading edge vs the falling edge? You don't need a high frequency, 440 Hz or something within a couple of octaves will do.
Scope or soundcard with a little scope software. Very easy to see.
Scope or soundcard with a little scope software. Very easy to see.
1. Binaural recordings, right. Good point!
. . . But I only have one working ear (Left); and there is no headset I know of, that puts both L and R channels into the L earphone.
I know, I can electrically join L + R into the Left earphone.
But paying for the right earphone that I can not use, is not a good use of my Money.
Besides, I do not want to be constrained by either an headset cord, or by a heavy battery headset that has either RF, optical, or magnetic pickup from the stereo system.
2. For any recording process that uses an equalizer . . .
Each of the 8, 12, 24, etc. frequency band controls Must preserve the exact phase
(0 degrees phase shift) of the signal that comes into the equalizer . . .
Right?
Wrong, it can not.
So, we have to eliminate all equalizers, right?
3. And, many recordings are not made at the same time and space, the piano plays on Saturday, the clarinet plays on Monday, the trumped plays on Wednesday. After the piano is recorded, the next instruments take their time and rhythm cues, by listening to the first track played back on a multitrack recorder.
Different microphones, different times.
There is no concert in this case, so no concert recording exists (and no audience out in the seats).
There is no "place in space" for that recording, no spaced omni's; no mid / side microphones; no crossed cardoid's; no binaural head, etc.
4. I am not saying that preserving the relative phase of the L and R channels is not important. It is important!
Out of phase L versus R channels bass cancels the bass.
Out of phase L versus R channels mid and high frequencies, does 2 things:
Drops the middle out;
And puts the music beyond (outside of) the spacing of the loudspeakers.
5. Recordings are what they are.
If you are looking for reality, please attend a live concert (and come back to the same seat after intermission).
Just my opinions
. . . But I only have one working ear (Left); and there is no headset I know of, that puts both L and R channels into the L earphone.
I know, I can electrically join L + R into the Left earphone.
But paying for the right earphone that I can not use, is not a good use of my Money.
Besides, I do not want to be constrained by either an headset cord, or by a heavy battery headset that has either RF, optical, or magnetic pickup from the stereo system.
2. For any recording process that uses an equalizer . . .
Each of the 8, 12, 24, etc. frequency band controls Must preserve the exact phase
(0 degrees phase shift) of the signal that comes into the equalizer . . .
Right?
Wrong, it can not.
So, we have to eliminate all equalizers, right?
3. And, many recordings are not made at the same time and space, the piano plays on Saturday, the clarinet plays on Monday, the trumped plays on Wednesday. After the piano is recorded, the next instruments take their time and rhythm cues, by listening to the first track played back on a multitrack recorder.
Different microphones, different times.
There is no concert in this case, so no concert recording exists (and no audience out in the seats).
There is no "place in space" for that recording, no spaced omni's; no mid / side microphones; no crossed cardoid's; no binaural head, etc.
4. I am not saying that preserving the relative phase of the L and R channels is not important. It is important!
Out of phase L versus R channels bass cancels the bass.
Out of phase L versus R channels mid and high frequencies, does 2 things:
Drops the middle out;
And puts the music beyond (outside of) the spacing of the loudspeakers.
5. Recordings are what they are.
If you are looking for reality, please attend a live concert (and come back to the same seat after intermission).
Just my opinions
Last edited:
Pano,
Good!
I like your method, a Sawtooth wave.
Unfortunately, my function generator has a Triangle wave, no sawtooth.
But . . . my Denon Technical Audio CD has a positive polarity uni-directional pulse.
It also has several frequencies of a few sine waves, they Always start in the Positive polarity.
Works for me.
Did you ever check the phase of all the L and R channel drivers in your loudspeakers?
Chances are, they are all correct, or you would be asking for help on the loudspeaker threads on diyAudio.
Good discussion, everybody!
Thanks!
Good!
I like your method, a Sawtooth wave.
Unfortunately, my function generator has a Triangle wave, no sawtooth.
But . . . my Denon Technical Audio CD has a positive polarity uni-directional pulse.
It also has several frequencies of a few sine waves, they Always start in the Positive polarity.
Works for me.
Did you ever check the phase of all the L and R channel drivers in your loudspeakers?
Chances are, they are all correct, or you would be asking for help on the loudspeaker threads on diyAudio.
Good discussion, everybody!
Thanks!
Do you want to test your system for relative phase, all the way from the preamp, power amp, speakers, and cabling?
No test equipment required.
Connect only the Left channel to both the L and R inputs of your preamp (use a hard wired splitter adapter).
Put on a music recording, with lots of frequencies in the music (bass, mids, and high frequencies - instrument harmonics).
(This method works best if you have loudspeakers that are a mirror image of each other)
Connect the speakers to L and R, but connect the wires of one of them in opposite phase (one connected 'incorrectly, at one end, and only one end of the one selected cable from amp to speaker).
Now, bring the speakers to face each other, 1 inch away.
If the sound is cancelled, that tells you that preamp, amp, and speaker all have the same phasing (we purposly reversed one speaker so they would cancel).
If you have either a Balance control, or separate volume controls of the L and R channels, carefully adjust them,
you can make that Null so deep, you will barely hear that signal.
Now, stop the playback of the recording right there, re-connect the one speaker with the correct wiring phase, and start the music again.
Aha, you hear loud music, there is no cancellation anymore.
No test equipment required.
Connect only the Left channel to both the L and R inputs of your preamp (use a hard wired splitter adapter).
Put on a music recording, with lots of frequencies in the music (bass, mids, and high frequencies - instrument harmonics).
(This method works best if you have loudspeakers that are a mirror image of each other)
Connect the speakers to L and R, but connect the wires of one of them in opposite phase (one connected 'incorrectly, at one end, and only one end of the one selected cable from amp to speaker).
Now, bring the speakers to face each other, 1 inch away.
If the sound is cancelled, that tells you that preamp, amp, and speaker all have the same phasing (we purposly reversed one speaker so they would cancel).
If you have either a Balance control, or separate volume controls of the L and R channels, carefully adjust them,
you can make that Null so deep, you will barely hear that signal.
Now, stop the playback of the recording right there, re-connect the one speaker with the correct wiring phase, and start the music again.
Aha, you hear loud music, there is no cancellation anymore.
Last edited: