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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

Showing 5 responses by jea48

jea48
4,266 posts
 
One sure way to check the drivers, crossover, and internal wiring of the speaker is to place a
1 - 1/2 volt D cell battery across the external speaker box terminals. Disconnect the speaker cables from the speaker box terminals. Connect two test lead wires to the speaker box terminals long enough so you can view the drivers from the front. Tag the test lead that is connected to the positive speaker terminal. Use your fingers to hold the neg test wire on the neg post of the battery. Momentary touch the positive test wire to the positive post of the battery. The woofer cone should push forward, not suck back.
Not sure if you will see any movement in the other speaker driver.
jea48
4,266 posts
 
Some driver manufacturers (JBL for example) use the oposite polarity definition (cone pulls in).
Eldartford,

True..... My point was to verify the polarity was indeed reversed on the driver/s and with the test make sure both speaker box units are in phase with one another. http://recforums.prosoundweb.com/index.php/mv/msg/2661/29039/0#msg_29039
jea48
4,266 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?
jea48
4,266 posts
 
Bryoncunningham,

I was not saying the two box speakers were out of phase with each other, they are not. I was saying the two drivers housed inside each box speaker are wired out of phase with respect to one another. Am I still wrong.

By chance have you listened to the Focal 1007be speakers, wired both ways, with the JL Audio Fathom F113 sub turned off?

No doubt you and Al are a hell of a lot smarter on this subject than I am.
jea48
4,266 posts
 
Kirkus,

That is the way I read the OP at first as well. But through later responses from Bryoncunningham I believe he just reversed the speaker cable leads at each of the box speaker terminals.


Anyway, a 180d change can produce a relative suckout in the lower-mid area, whereby the perceived result is more clarity ion the upper register (=better imaging) and a more pronounced upper bass region.
02-24-10: Gregm

Gregm,

What if instead of reversing the polarity at the box speaker terminals Bryoncunningham pulled the midrange/hi-frequency driver and reversed the polarity there? Then reconnect the speaker cables from the amp to the speakers + to +, - to -.
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