This is great Brad. It explains a lot for me especially in terms of experiences both with my Maggies and also the Pureaudio project Trio horns both as dipoles.
Getting the reflected sound in just the right timing in delay, coherently and just in the right balance with the direct sound is the thing for me that snaps both these speakers into sounding more real and alive.
The Maggie 20.7s when dialled into the room just right are 3D imaging machines.
My work with the Trio OB horns has been to get them to do everything in similar competencies to the best aspects of the Maggies with the big added advantages of their effortless dynamic natural horn nature for fine texture and then to scale up big and fast as well as the invaluable (to me) capacity for SET to drive.
With the new larger horns I’m under way on now I’m now thinking when I get in the Radian beryllium CD and Seos waveguide I will then also be able to try using the Pap iwata with the Beyma CD for rear firing duties as well.
I’ll likely be able to crossover at the same point as the Radian Seos front horn and just use an L-pad to set the right balance level with the rear horn. Getting perhaps a bit ahead of myself but now that seems to me very much worth exploring as well.
Super excited to try this out, very big thanks guys for bringing this all to light.
I am actually thinking, what if I simply take the back cover off of the compression driver? As you probably know, these drivers are essentially inverted domes with the concave part coupling to the horn throat and the convex side of the dome firing into a damped back plate. Just removing that plate would expose the convex (dome) side of the diaphragm and would act as a natural dipole. Why bother with another driver when you already have a dipole handy?
Now, what the Carolus was doing was another driver wired in phase with the front one, which makes a bipolar response. This is not how panel speakers or open baffle speakers work as the back wave is out of phase with the front one, making it a dipole. Which is more correct for creating a sense of space? I am not sure but would be worth the while to experiment and what easier way than just to take the back cover off your compression driver. You could do it with the PAPs right away. With my Odeons it is not possible but with my other system, where the horn sits exposed, I don't see why not to try it.
It shouldn't impact the driver as I think the system doesn't rely on pressure in that chamber for anything. I think the diaphragm is wholly controlled by the very powerful magnets used and the compression chamber is on the other side of the diaphragm.
Maybe someone can correct me if I am wrong about this.