Forgot to mention, the W15s hardly move crossed with a 250hz Fc. They play loud enough to make my ears hurt- while not coming close to xmax limits.

Rob,

The best thing you can really do to truly know what is going to happen in the dipole is to measure. The speaker that you see in my avatar does not have a U-frame yet, but adding small sides to the left and right side smoothed out the response around 1.5k. I then was able to use a filter that has a smoother electrical tranfer function, which I will estimate will have a smoother power response. In my opinion, the Tombstones are now even better than what the judges heard at DIY Dayton- ranked higher than the winner by Joe D'Appolito, Roy Allison, etc.

The original speaker has gone through some improvements with the addition to the shape of the midrange baffle. As a designer I can't help but see if things can be even better. I continue to tweak and measure to see what can be learned. I took cardboard to make different lengths to the frame and measured the results in each situation. Adding a "wing" to the top actually made the response worse. There is a lot of trial and error with an irregular shaped baffle, such as used in the Tombstones.

Since the bass is monopole in my Tombstones, it wasn't hard at all crossing over at 250hz with a LR4 acoustic slope.

The MTM section is crossed around 1600hz LR4. Low enough to solve the ringing problem/cone breakup of the W15s, and also not too low that the hybrid DXT tweeter can't handle it. I would say every design element to the Tombstones was the direct result of something I learned from experiments in the past. That leads to the sum of the parts, which equal a very neutral speaker with a large soundstage.

Jed

Hi Rob, I used a few different methods- the BDS software program, studying the work done by Linkwitz, and then experimentation and actual measurements. I recently discovered a way to flatten the response even flatter, and I will be implementing that approach in a small crossover revision. It just involves placing 2 1.5" wings at the ends of the baffle to make a small U-frame. I kept the layout symmetrical to get a uniform polar response, and the curve on the top actually seems to help the tweeter response. I recently measured an XT25 in this same baffle and it was just about perfect. I also cross low enough to the tweeter to eliminate the baffle ripples that might result in the symmetrical mid layout. As you can see in my published graphs on my website, the response is very flat.

http://clearwaveloudspeaker.googlepages.com

Jed