Out of phase rears increases base

RobinKidderminster

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Sofa against rear wall and speakers close to our ears when listening two up led me to try swapping signal leads to the rears to try a more diffused rear channel. I have found the result interesting but it also seems to have significantly altered the base response. Never happy with the sub position but sudenly it seems to have come to life. I will continue to experiment with sub phase now but I am posting to see if others have found phase changes to rears have been interesting.

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MajorFubar

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Back in the early days of analogue surround sound when people cobbled together their own surround systems, I read that the rears should push while the fronts pull, and vice versa, so that they don't cancel each other out in the middle. In effect that means you have to wire the rears in reverse. With modern digital surround with discrete channels, you'd think the amp would sort all that out.
 

RobinKidderminster

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Agreed major - I wonder if the effect depends somewhat on the room acoustics. Set things up according to the science and then experiment. I think the sofa against the wall and close to side walls maybe throws the 'normal settings' aside. Still can't understand the bass increase tho.

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MajorFubar

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Bass is the first thing which suffers as a result of phase cancellation, because its wavelengths are very long. Pipe an identical mono signal to two identical out-of-phase speakers, place the speakers facing each other about a foot apart and you will notice that the bass cancels-out more than any other part of the frequency range. The strange thing is, rear channels often don't carry much bass, so it is unusual that you're experiencing what sounds to be phase-cancellation at the bass end. But my view is, if what you've done works for you, then hey, stick with it! :)
 

RobinKidderminster

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Mmmm - I wonder if cancellation is the effect since I too would expect (if anything at the lower end) the bass to be less. I'd like to hear of any who have tried reversing the rears phase - I certainly think the surround has improved (since they are so close to our ears) in widening the sound stage but the bass extension is a great bonus.
 

MajorFubar

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RobinKidderminster said:
I wonder if cancellation is the effect since I too would expect (if anything at the lower end) the bass to be less
That's what I meant: reversing the polarity of the rear speakers appears to have stopped the cancellation.
 

RobinKidderminster

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Aha ! Genius ! I guess that may be the explaination. Anyone want to join the Rear Phase Reversal Club? Thanks Major. I may test the theory by changing the crossover frequency to see the effect (just for fun).
 

MajorFubar

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As I said before though, I can't really figure out why it's made such a difference, because most rear channel audio doesn't contain huge amounts of bass to start with. But if it has, then it has.
 

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