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Polarity mystery: Can you help me solve it?

THE BACKGROUND: My speakers are Focal 1007be. They have a Linkwitz-Riley crossover with a 36 dB per octave slope. Because of that, the two drivers are wired with opposite polarity: the woofers are positive, the tweeters are negative.

WHAT I DID: At the advice of a friend with the same speakers, I inverted the polarity of the drivers, by simply reversing the red and black speaker wire leads to the terminals of both speakers, so that the speakers are still in phase with each other, but now the woofers are negative polarity and the tweeters are positive polarity.

WHAT HAPPENED: To my surprise, the sound improved! Specifically, image focus improved. The improvement can't be attributed to the preservation of the absolute phase of the recording, since the improvement was the same for many different recordings (some of which, presumably, preserve absolute phase, while others do not). And the improvement can't be attributed to the speakers being wired incorrectly at the factory, since the friend who suggested that I try this experiment owns the same speakers and experienced the exact same result. So I don't know what to attribute the improvement to.

Can anyone help with this mystery?
bryoncunningham
bryoncunningham OP
890 posts
 
Another thought: I wonder if it has something to do with how the sound from the tweeter and woofer "sums" at a particular listening distance.
onhwy61's avatar
onhwy61
5,229 posts
 
I looked at your system page, but I don't see any pictures of the room. Does your room contain many highly reflective surfaces? If so, from looking at the Stereophile measurements, the reversing of the driver polarity could result in a mid-treble suckout which would have many of the sonic effects you descibe. Stereophile concludes that the speaker is best suited for a large, well damped room. If that's not a description of your room, then intentionally having the speaker malfunction might actual work better.
almarg's avatar
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almarg
9,670 posts
 
Perhaps it is Folie à deux!
LOL!
I wonder if it has something to do with how the sound from the tweeter and woofer "sums" at a particular listening distance.
Does your room contain many highly reflective surfaces? If so, from looking at the Stereophile measurements, the reversing of the driver polarity could result in a mid-treble suckout which would have many of the sonic effects you descibe.
It seems to me, as I indicated earlier, that while all of these are factors that may be relevant in a general sense to the sonic characteristics of the system, they are inapplicable to the observations Bryon has stated. The reason being that they would not have effects which are simultaneously consistent both with connection polarity and across recordings that maintain absolute phase, that have inverted absolute phase, and that have randomly mixed phases.

It seems to me that that observation, of consistency across many recordings, shoots down all of the theories that have been offered, aside from mine which has been shot down in other ways.

Best regards,
-- Al
bryoncunningham OP
890 posts
 
Onhwy61 - No, my room does not have many highly reflective surfaces. It has a thick rug over a wood floor and 2" acoustical foam over a large area on the ceiling. Both side walls and the wall behind the speakers contain diffusion. Also, the room is not particularly small - it is 14x17x8.

However, there is something implied in your theory that seems plausible to me, namely, that somehow the crossover design could be relevant to my (and my friend's) findings.

Al - Assuming that the improvement I experienced really is constant across all recordings, regardless of their polarity, then surely we are right to conclude, as you and I both have, that the ABSOLUTE polarity of the recordings is irrelevant to the issue. But does it follow from that, that the RELATIVE polarity of the tweeter/woofer is irrelevant to the issue? I'm getting a little lost in the how that inference works.

BTW, I don't know if it's relevant, but the two drivers are not on the same plane. The woofer is recessed in the speaker cabinet, so that its center is slightly farther from the listener than the tweeter.
jea48
4,453 posts
 
I inverted the polarity of the drivers, by simply reversing the red and black speaker wire leads to the terminals of both speakers, so that the speakers are still in phase with each other, but now the woofers are negative polarity and the tweeters are positive polarity.
Bryoncunningham 2-18-10

so that the speakers are still in phase with each other,
Am I wrong, aren't the two speakers still out of phase with one another.

If the woofer, bass driver, is now wired so when a kick pedal strikes the bass drum does the speaker produce the same amount of energy, air movement, sucking back as it did wired the other way pushing out? Does the woofer now produce less bass?
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