Planning stages of some dipoles for my rear L/R/C speakers

[wigginjs]

I'm planning some dipolar speakers to take the positions of rear left, rear right, and a bipolar speaker for a rear center in my home theater. One thing I'm not sure of is how to calculate the box volume/tuning frequency when the speakers will be playing out of phase, is it the same as if they were playing in phase? I had these in mind for the woofers and these in mind for the tweeters. I'm also curious if I'm going to need some sort of impedence correction circuit in the crossover.
I would be using essentially the same design for all three speakers, the only difference being that the rear center would be bipolar instead of dipolar. Any suggestions would be much appreciated, I've never designed a speaker like this before and I'm having a little trouble understanding how the enclosure and crossover should be designed.

[Volenti]

I'd be little hesitant about engaging metal cone drivers for effects speakers, a lot of trouble to go to x-over wise (steep x-over point, notch filters ect)

With poly cone mids and a cloth/silk dome tweeter you could get away with a very simple x-over (possibly as simple as a single cap on the tweeter)

That said the dipole speakers would use the same enclosure dimentions as the bipole version, easier to mix and match if the dipole effect doesn't work for you.

[Timn8ter]

Just for clarification because I've been corrected on this and want to make sure I'm understanding the proposal.

Bipole = Two drivers in a box firing in different directions.

Dipole = Open baffle.

Right or wrong?

My understanding is a dipole speaker can also mean two drivers in a box firing in different directions but out of phase.

[wigginjs]

The term dipolar does not imply "open baffle". A dipolar speaker has at least one pair of drivers that fire out-of-phase in relation to one another. A bipolar speaker has at least one pair of drivers that fire in-phase in relation to one another.

In-phase meaning both speakers would push out and pull in at the same time. Out-of-phase meaning that one driver would be pulling in while the other is pushing out. Drivers playing out-of-phase produce a "diffuse" sound, meaning that the sound is difficult to localize, bipolar speakers produce a wider field of sound (which is why a bipolar design is often used in center channel speakers).

This information is accurate to the best of my knowledge.

[Timn8ter]

Originally posted by m0tion
The term dipolar does not imply "open baffle". A dipolar speaker has at least one pair of drivers that fire out-of-phase in relation to one another. A bipolar speaker has at least one pair of drivers that fire in-phase in relation to one another.

In-phase meaning both speakers would push out and pull in at the same time. Out-of-phase meaning that one driver would be pulling in while the other is pushing out. Drivers playing out-of-phase produce a "diffuse" sound, meaning that the sound is difficult to localize, bipolar speakers produce a wider field of sound (which is why a bipolar design is often used in center channel speakers).

This information is accurate to the best of my knowledge.

Yep, that's the way I understand it too. I was corrected on another forum so I wanted to double-check. Thanks.

[RHosch]

To be absolutely clear, dipolar speakers can use a pair of speakers pointed in opposite directions and moving out of phase, or a single speaker on an open baffle (where the rear of the cone motion acts the same as the second out-of-phase speaker in an enclosed dipole speaker).

Around here, I think dipole is typically used in conjunction with the open baffle type.