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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
kirkus
502 posts
 
Kirkus - In light of this information, does your initial crossover/driver/cabinet theory still apply?
No, sorry, it doesn't. There are only three things that I can think of can explain what you're experiencing:

- Psychological or experimental change, like improving the speaker connections in the process.

- In your room, with your system, and with your program material, reversal of absolute phase make enough of a difference enough of the time, in the right way, to be perceived as an improvement

- The amplifier somehow performs slightly differently when its connection to the speaker is reversed. Speculation about this in further detail would require some pretty obscure types of data to be measured pertaining to the loudspeaker, the amplifier, and the speaker cable . . .
bryoncunningham OP
890 posts
 
- In your room, with your system, and with your program material, reversal of absolute phase make enough of a difference enough of the time, in the right way, to be perceived as an improvement.

This explanation is looking more and more likely. I hope I have not been wasting everyone's time with what is nothing more than a psychological phenomenon!

In any event, thank you for your thoughtful effort to help me diagnose the issue. Likewise for all other posters.
almarg's avatar
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almarg
9,670 posts
 
This explanation is looking more and more likely. I hope I have not been wasting everyone's time with what is nothing more than a psychological phenomenon!
The thread strikes me as having been a very worthwhile intellectual exercise, with the thoughts that have been presented having potential applicability to other situations in the future. Not a waste of time at all.

Best regards,
-- Al
rleff
1,065 posts
 
I agree with Al.
glai's avatar
glai
446 posts
 
Along the same lines, I have Verity Sarastros which have first order crossovers, all drivers in same polarity with rear facing woofer. As a result, there is large overlap of the midrange and woofer. My room has some inherent narrow band peaks at 50Hz and 80Hz. When I invert the polarity of the woofer, these peaks completely went away and I was left with a near ideal frequency response with no peaks. Base is cleaner, tighter. The soundstage is deeper but some instruments are more difficult to localize in the soundfield. I am bit surprised because violins does not have much energy below 100Hz.

I understand that there is more to just a flat frequency response. What is the ramification of this?
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