invert one driver leads or not?

[dallaire]

I've been tring to gain some knowledge of all this "phase" and "time" stuff introduced by crossovers and what it does to frequecy and transient responses and all. My ultimate question is sould one reverse the leads of one driver in a two way system? or just a three way system "mid reversal only"? And does this make no difference if it is passive or electronic? I am using 24db per octave/electronic setup. Or should I just measure with my software and mic to see which one has the best frequency response????
dallaire

[Svante]

In theory, phase should be shifted on filters of orders 2, 6 10, 14 etc. Filters of order 4, 8 12 etc should not be shifted. Odd order filters can be shifted, but are typically not. The rsponse is flat in both cases.

This is the theory. In real life the drivers' phase and amplitude responses messes things up. A nice and clean 24 dB/octave Linkwitz filter becomes a 36 dB/octave of-some-unnamed-sort and if the phase is to be reversed is different in each case.

In the passive case, the drivers' impedance changes things even more.

These is are good reasons to not see the crossover filter as an ideal box that sends bass to the woofer and treble to the tweeter. It should rather be seen as a place to compensate for various shortcomings in the system at almost no cost. The only thing needed is a few measurements and adjustments.

Crossovers should not be designed at the desk.