Here it is, an Ewave type center channel, dubbed "Malcolm
". It uses a SEOS12 and (currently) one of Erich's "less good" clone drivers.
Almost done, just a little tweak needed on the crossover to smooth the curves a little more. Weather was good tonight and I had a little time to set up outside and take some pattern measurements. When I get some more time and energy, I'll work up a schematic and parts list and post it all as a build article on Erich's forum (if he ever opens it up, that is). Maybe he'll even do kits on it.
Woofers are 4x DS-115-8, cleverly (or so I think) arranged as a shaded horizontal line source. Near crossover, the middle pair plays dominantly to match the SEOS12 pattern, with the outer pair cutting in a few hundred Hz lower and continuing directivity like a 20" driver. The effect is rather good constant horizontal directivity down to about 500Hz, in a box only 12" high and 21" wide. 8" deep. The speaker cabinet looks a lot better than it appears in the camera photo (the flash does funny things inside the waveguide contours). The crossover mess on top, though, is every bit as ugly as it looks here -- needs to be put on a board and mounted inside.
The box is ported, tuned to 60Hz and has an F3 of about 57Hz when mounted against a wall (above or below an LCD monitor is the intention).
Here are the Horizontal curves, unsmoothed. 0 to 60degress in 7.5 degree steps-
Pretty good, huh? Check it out in the usual 1/6th Octave smoothing (0 to 90deg):
These are some color polar plots of the horizontal performance (map and cylinder formats):
In the vertical, the waveguide can only control directivity down to about 3kHz or so and the woofers (being only 4"ers) don't control it at all. But the very close 5.5" CTC keeps the curves smooth and useful so what does go vertically off axis is at least well-behaved. Vertical Upwards, 0 to 60, unsmoothed:
And here's the high-tech measuring "lab", including speaker precariously balanced on a ladder with a sheet of MDF clamped below to try to simulate an LCD screen. The whole arrangement is about a foot from the door behind it, so bass wasn't as good as it should be.