MotherSky

Phase inversion

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36 minutes ago, Ron Hilditch said:

If polarity is immaterial,  why do manufacturers bother with colour coding + & - ?  

Well, for one thing, negative is often connected to ground, so rather important.  And if you use a subwoofer, or have an active system (as I used to) then you need all the amps connected the same way round.  Or at least know which way round they are.

For recordings, it probably is unimportant.

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Super Wammer

I have said this on here before - I believe that I hear a slight difference if I play something in absolute phase vs. Inverted phase. My understanding is that set one way, the cone/panel etc. will move forwards and set the other way, it will move backwards. I have Quad Esl63 electrostatics which are therefore dipoles rather than sealed boxes. If for example, a drum is hit and the phase is incorrect, the panels will initially move backwards rather than forwards, would they not? Is it not then possible that this soundwave could reflect from the wall and partly cancel out the sound emanating from the front of the speaker, making it quieter than it would be if the phase was correct? This would match with what  I seem to hear. 

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11 hours ago, Gizza said:

I Is it not then possible that this soundwave could reflect from the wall and partly cancel out the sound emanating from the front of the speaker, making it quieter than it would be if the phase was correct? This would match with what  I seem to hear. 

Hmm, I'm not sure if that would make a difference compared with correct polarity, but hopefully someone can provide some more thoughts on that.  When you hear this happening, can you move the speakers closer to or further from the rear wall and listen again?  That should change the frequencies affected. As this is the Tech Corner, maybe you can make the effort?  I understand it may not be feasible.

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Super Wammer
9 hours ago, awkwardbydesign said:

Hmm, I'm not sure if that would make a difference compared with correct polarity, but hopefully someone can provide some more thoughts on that.  When you hear this happening, can you move the speakers closer to or further from the rear wall and listen again?  That should change the frequencies affected. As this is the Tech Corner, maybe you can make the effort?  I understand it may not be feasible.

I have them sat on top of matching Gradient Subwoofers,  which are spiked and together, they are very heavy and difficult to move. It's also difficult to get them back into their exact original position. What I do hear, however, when the phase is wrong is a different quality in the bass (the timing is less clear) and less immediacy in the mids and treble. It's as though the sound is coming more from the rear of the speakers. 

Unfortunately, I cannot make measurements to prove or disprove what I think I'm hearing, so it's purely subjective.

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Super Wammer
14 hours ago, Gizza said:

I have them sat on top of matching Gradient Subwoofers,  which are spiked and together, they are very heavy and difficult to move. It's also difficult to get them back into their exact original position. What I do hear, however, when the phase is wrong is a different quality in the bass (the timing is less clear) and less immediacy in the mids and treble. It's as though the sound is coming more from the rear of the speakers. 

Unfortunately, I cannot make measurements to prove or disprove what I think I'm hearing, so it's purely subjective.

If you are only changing the phase of the main speakers and not the sub, then you will get an audible difference. Changing the phase of all the speakers simultaneously will have no audible effect.

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Super Wammer
Posted (edited)
1 hour ago, chris217 said:

If you are only changing the phase of the main speakers and not the sub, then you will get an audible difference. Changing the phase of all the speakers simultaneously will have no audible effect.

Ah, I know that and the phase of the subs is always changed at the same time as the main speakers. I have the option of flipping the phase via my Audio Synthesis dac or via my minidsp  digital x-over, both of which come before my power amplification stage. I have 2 sets of monoblocks, one set drives the main speakers, the other drives the subs.

I have no problem with people telling me that there will be no audible difference and that I am imagining a difference. I will, however, continue to try each setting when I begin playing my music, thank you, as it always sounds better one way or the other to me. I do think it may be due to the speakers being dipoles (the subs are open baffle dipoles too). 

Edited by Gizza

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6 hours ago, chris217 said:

If you are only changing the phase of the main speakers and not the sub, then you will get an audible difference. Changing the phase of all the speakers simultaneously will have no audible effect.

How do you know this?  Have you tried it, as Gizza has? Do you have dipoles?  Or are you making untested assumptions?

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Super Wammer
On 01/07/2018 at 15:50, awkwardbydesign said:

How do you know this?  Have you tried it, as Gizza has? Do you have dipoles?  Or are you making untested assumptions?

Actually, my speakers are dipoles. :cool:

I know this from experimentation, an understanding of the physiology of the ear as well as with the physics and mathematics behind it.

Whilst there are certain very specific circumstances where phase changes can be audible, these are most unlikely to occur in a musical context.

There is a lot of useful information in David Benson's book, available here. Specifically, sections 1.2 and 1.3 cover the physiology of the human ear, whilst there is a reference to a phase-based audio illusion on page 151 (PDF page 165).

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