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Question about speaker phase.


gagelle

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Hello all,

My son the original klipsch Forte speakers. He used one of those CD cleaner disks that contains a phasing test. Well, the test indicated his speakers were not in phase. We checked the wiring about ten times: Positive to positive and negative to negative from a restored Sansui 9090DB. We then tested two other Klipsch speakers, a pair of KG 1.5 with the same result. The second sound on the disk is supposed be softer and it isn't. All the speakers are original except for the installion of new Crites tweeter titanium diagraphams on the Fortes. Last night, my son read an article that states these phase testing disks don't work on some speakers, due to the way the crossover is set up. They sound fine, with plenty of deep bass. Anyone have an idea about this situation? Thanks in advance.

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The discs aren't always correct. If they sound OK and the wiring is fine, don't worry about it.

Thanks very much. That's what i thought. I even tried a new integrated amplifier to eliminate the Sansui as a source of the problem.

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Hello all,

My son the original klipsch Forte speakers. He used one of those CD cleaner disks that contains a phasing test. Well, the test indicated his speakers were not in phase. We checked the wiring about ten times: Positive to positive and negative to negative from a restored Sansui 9090DB. We then tested two other Klipsch speakers, a pair of KG 1.5 with the same result. The second sound on the disk is supposed be softer and it isn't. All the speakers are original except for the installion of new Crites tweeter titanium diagraphams on the Fortes. Last night, my son read an article that states these phase testing disks don't work on some speakers, due to the way the crossover is set up. They sound fine, with plenty of deep bass. Anyone have an idea about this situation? Thanks in advance.

I assume you are writing about whether the whole left channel speaker is in phase with the whole right channel speaker, rather than whether the speakers within one speaker box are in phase with each other, right? If so, I'd wonder about the disk, especially since the same thing happened with the KG 1.5s. I've heard of some tweeters being deliberately wired out of phase with mids or woofers, but that was done to compensate for design problems (I think EV did that with some of their speakers).

The Stereophile Editor's Choice sampler & test CD has a simple, effective, phase test near the beginning. They play a Bass Guitar through the left, then the right channel, to let you identify the channels, then they play it centered & out of phase ... the guitar seem to come from "everywhere" and nowhere in particular. Then they play the same center image for the guitar from halfway between the speakers in phase, and it should be perfectly centered between them (if you are directly in front). There will be no doubt. This disc is still available for sale online from Stereophile. I'd try it, and if it shows your son's speakers to be in phase, send the other one back, with a little note. :)

Or, hold off a few days, and you may get better answers from forum members.

If your problem is the phase within a box, Bob Crites might be of help online. He is a very cooperative guy.

Edited by Garyrc
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In the past, I have put speakers face to face to determine any questions regarding "phasing."

I have never heard of this. What should one expect doing this?

It gives you (not scientific) a chance to hear if the drivers (especially by listening to the woofers) "sound" in phase..... If the speakers are not in phase they sound disjointed. If they are in phase the balance is very much evident....

This used to be very helpful to me when I employed AR speakers.

Edited by Boxx
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Of course this is not a phase test. The correct term is polarity test. Reversing the speaker wires cannot change phase.

Wouldn't that make them 180 degrees from each other, thus making them 'out of phase'?

I know of studios that would set up two speakers facing each other, wired out of phase, with a single microphone in the middle. With sound from the two speakes would cancel out/null at the center, and allow a group of singers to listen to the track to sing along with. The mic would pick up their voices just fine.

Bruce

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Of course this is not a phase test. The correct term is polarity test. Reversing the speaker wires cannot change phase.

Wouldn't that make them 180 degrees from each other, thus making them 'out of phase'?

Bruce

No. To effect a phase shift of 180 degrees one would need to start the second sine wave half way through the first wave's cycle, or 180 degrees after the start of the first wave. When the polarity is changed both waves start at the same time, hence no phase shift. Manufacturers of pro sound equipment usually mis-mark the polarity reverse switch on the channel strip inputs on a mixer as "phase", so that term is often misused when polarity is what is really meant. Polarity reversal can cause complete cancellation whereas phase shifts of 180 degrees will not cancel the first half-cycle of the first wave.

Edited by Don Richard
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Reverse the phase on one speaker, push them face-to-face, and play FM interstation noise. You should hear virtually nothing when the drivers are in phase. If you hear any bass, one is out-of-phase, if you hear any mids...............

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Reverse the phase on one speaker, push them face-to-face, and play FM interstation noise. You should hear virtually nothing when the drivers are in phase. If you hear any bass, one is out-of-phase, if you hear any mids...............

Once again, one can reverse polarity but not phase in the manner that you have described. This article should clarify the matter. Enjoy:

http://www.communitypro.com/files/literature/tech%20notes/POL_PHASE_TECH.pdf?phpMyAdmin=c9cc5b3953d87385dc22218d669e7aab

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Can you set all frequencies out of phase by 180°? I suppose with computers you could. It would be easier to just reverse polarity.

I'm not being a smart a$$. I just read through the Polarity and Phase document, and really do wonder if phase can be shifted for all frequencies at once.

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