3 way frustration :(

[PWR RYD]

I have modeled, modeled, and modeled some more, and have come up with what I think is a fantastic looking and simple 5.25"/1" MTM design, except that the bottom end rolls off at about 180 Hertz (sealed enclosure). So my thought is: "Hey, let's turn this into a passively crossed MTMW or MTMWW". However... when I enter what was the M as the mid and apply the same crossover components for the mid to high, then add the high pass components to the mids everything falls apart. The phase looks terrible. The beautiful reverse null is completely gone. I believe that each order of electrical filter adds 90 degrees of phase shift. So my mids and tweeter are connected reverse polarity.

The MTM crossover point is 2500 Hz with LR4 slopes. The Woofer to Mid crossover point is 350 Hz with LR2 slopes.

Any suggestions are greatly appreciated. Thanks!

[Face]

http://techtalk.parts-express.com/showpost.php?p=1546062&postcount=34

[Pete Schumacher ®]

I have modeled, modeled, and modeled some more, and have come up with what I think is a fantastic looking and simple 5.25"/1" MTM design, except that the bottom end rolls off at about 180 Hertz (sealed enclosure). So my thought is: "Hey, let's turn this into a passively crossed MTMW or MTMWW". However... when I enter what was the M as the mid and apply the same crossover components for the mid to high, then add the high pass components to the mids everything falls apart. The phase looks terrible. The beautiful reverse null is completely gone. I believe that each order of electrical filter adds 90 degrees of phase shift. So my mids and tweeter are connected reverse polarity.

The MTM crossover point is 2500 Hz with LR4 slopes. The Woofer to Mid crossover point is 350 Hz with LR2 slopes.

Any suggestions are greatly appreciated. Thanks!

Yep, the HP can affect the LP section, but the 90 deg rule doesn't apply at the XO point. You just need to insert the HP and adjust the LP to fit the target. Filter order stays the same, but phase will re-align. More than likely, you can get away with a single HP capacitor for your mid.

Go for LR2 at 350, which means you need to invert mid polarity, and tweeter polarity, if you do LR4 at 2500.

[PWR RYD]

Yes, mid and tweeter are in phase with each other but both are out of phase with the woofer(s).

[Pete Schumacher ®]

Yes, mid and tweeter are in phase with each other but both are out of phase with the woofer(s).

If the mid/woof XO looks good, then just keep working on the MTM section, until you restore the nice result you had before. You'll probably wind up with a system that's at about 3dB more sensitive overall, since the woofer is now handling all the BSC duties.