Fix polarity issue on mid-speaker with 2nd order filter?

[mirko88]

I noticed a polarity issue in my 3-way compo and 2-way compo sets when doing an absolute polarity test (test tone and polarity tester).
With the 3-way compo the mids are out of phase and with the 2 way compo the tweeters are out of phase, even though all components are correctly wired.
Didn't know filters could cause this, but with some searching on the web I learned 2nd order passive filters cause this reversed polarity of the mid.
I can't find in the specs of my Focal 165KRX3 and 165KRX2 if the crossover filters are actually 2nd stage, but for this topic I'm assuming and I'm in the process of finding this out from Focal.

Now, in my search for info on this polarity thing, I read a lot of technical explanation about why the reverse polarity is there (has to do with the 12dB slope), but I can't find the practical translation if this polarity reversal is actually accoustically a good thing and I should leave it like that in my setup, or if I better reverse the wires to the mid driver, so I cancel out the polarity reversal in the filter and bring the mids back into phase with the woofer and tweeter?

Does the same apply to my tweeters showing reversed polarity as well on my 2-way compo?

Any practical advise is highly appreciated

[TaylorFade]

Usually, in 2 way the tweeter is mounted 'out of phase' for a 2nd order highpass because at crossover frequencies the signals would sum. And since 2nd order filters have a 180 ° phase shift, putting the tw reversed would optimize output. in a 3 way system, the midrange is often reverse -phased, and the tweeter 'normal' for the same reasons.

My advice is to listen to them the way they're designed and then flip them to see if it's better. Just use whichever sounds better to you since your install will affect the polarity as well.

See here... at low frequencies, the output is in phase with the input. At the crossover frequency, the output is 180° out of phase with the input. At high frequencies, the output is 360° out of phase with the input. They sum at the crossover frequency.

[mirko88]

Great info, thanks!