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Old 1st September 2005, 08:44 PM   #1
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Lightbulb About the importance of Phase adjustment !!!

Hello fullranger addicts !!!


I've just finished a fullrange system set-up (my home theater front satellites), and I've been amazed by a little thing called "phase adjustment".

I used the THX optimizer found in a movie (eg:Star Wars) and launched the different optimization programs.

The phase adjustment sends a mono tone (seems to be some kind of pink noise) on two opposite speakers, in my case, the front sats.

Out-of-phase, the sound is difficult to locate, and you separately hear the two speakers.

In phase, the tone should be heard precisely centered between the speakers, like if coming from a physical center speaker.


It is the most obvious adjustment I've ever heard ! My speakers where definetely out-of-phase !

The solution to this, according to the THX optimizer, was to reverse the speakers connexions. I did it.

I stopped the movie and launched a CD.

WOWww !

Immediately, the music was brought to another dimension. The singer's voice was well-located at the center of the soundstage, and the stereo separation was more obvious. More than this, the highs got immediately sharper, the percussions were light, aerial, brilliant, fast, and runned from left to right with ease.

I litterally rediscovered my speakers ! Before, I found them flat, hollow and I thought they had not a good imaging for fullrangers. I just found them good enough for the price.




Surprised by this, I asked myself : why do I have to reverse the speaker's connexions ? it must mean the speakers arent' synchronized due to their position !

I moved one speaker slowly with the THX movie running, until the tone sounded correctly with the connexion plugged normally. It was just about centimeters !

Then I asked myself : if it is a phase problem, it is something progressive, and must be set precisely.

I found the pink noise tone was not accurate enough for this smooth adjustment.

I launched again my CD, and adjusted the speaker's position with patience. I used the singer's voice as reference.

Half an hour after, I got the perfect position. Now, I could hear everything with a positionning precision I never heard before. I could hear until the singer taking her breath behind the instruments, until her saliva between her teeth (I'm not laughing lol !!), and I really believed I had a physical center speaker.

The difference between two speaker positions was audible +/- 5mm !!

It was really worth a try, my speakers are now transfigured !

I can only recommend you doing this yourself, it is very well spent time.


And now, I understand the superiority of a fullrange driver on every other concept : one source, one wave, no phase decay possible.

And I now know what imaging means !
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Old 1st September 2005, 10:16 PM   #2
Dumbass is offline Dumbass  British Antarctic Territory
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Stereo speakers that are out of phase which each other sound like ca-ca. And have no low end.

I have an old test record that has a phase test, makes the difference quite obvious.

I don't know about absolute phase. Apparently different CDs even have different absolute phase directions!
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Old 2nd September 2005, 07:45 AM   #3
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Yes, some CDs have a reversed absolute phase, but in this case, both channels are reversed, and they are still synchronized.

The CD I use is a compilation of musics and test sounds I burnt myself; with samples of the hardest music material I listen to.

I think there are not so many people who know about phase adjustment, and they would really appreciate the difference I think.

Concerning the out-of-phase sound, I rather found the speakers had no high end, though the low-end suffered also. At the beginning I thought it was a problem with the brand new DVD player (a Pioneer DV585, very good BTW) !

That's why I posted this
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Old 2nd September 2005, 02:06 PM   #4
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by youyoung21147
Yes, some CDs have a reversed absolute phase, but in this case, both channels are reversed, and they are still synchronized.

The CD I use is a compilation of musics and test sounds I burnt myself; with samples of the hardest music material I listen to.

I think there are not so many people who know about phase adjustment, and they would really appreciate the difference I think.

Concerning the out-of-phase sound, I rather found the speakers had no high end, though the low-end suffered also. At the beginning I thought it was a problem with the brand new DVD player (a Pioneer DV585, very good BTW) !

That's why I posted this
It sounds like you've been baptized.
When you get to the point where you hear the difference between the absolute phase, you've reached new highs.
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Old 2nd September 2005, 03:28 PM   #5
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lol, I never tried recognizing the absolute phase of a music, but it may be worth a try

Maybe it will be easier with techno music


I try to profite of my young ears before they get worn

My grandma cannot hear higher than 7kHz lol
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Old 2nd September 2005, 07:33 PM   #6
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Quote:
Originally posted by Dumbass
I don't know about absolute phase. Apparently different CDs even have different absolute phase directions!

The Wood Effect

Interesting article on absolute phase.
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Old 2nd September 2005, 08:13 PM   #7
eLarson is offline eLarson  United States
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To date I've never heard the difference this or that phase makes. I may never hear it. I suspect I'll need a better listening room.

I have noticed that when my speakers are 'just so' sibilants are MUCH cleaner.
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Old 3rd September 2005, 12:07 AM   #8
soongsc is offline soongsc  Taiwan
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Quote:
Originally posted by tgorham3



The Wood Effect

Interesting article on absolute phase.

I couldn't have explained it better.
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Old 3rd September 2005, 05:12 AM   #9
Dumbass is offline Dumbass  British Antarctic Territory
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Quote:
Originally posted by soongsc
I couldn't have explained it better.
Now I'm contemplating how to build a remote control phase switch into my preamp.

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Old 3rd September 2005, 08:15 AM   #10
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Yes, very interesting article.

Maybe one day I'll try reversing my speakers

But I'm a little sceptical about their metal orientation in cables, as far as sound is AC signal.


I'd be very interested to have a phase adjuster on my amp/preamp. The best thing would be a progressive adjustment for each channel, like on the best sub modules
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