Our ears are sensitive to early reflections. It's why most of us treat the first reflection points in our room with some absorption. The idea with avwaveguide, when properly implemented, is that they can significantly reduce the occurrence of early reflections and at the same time, promote the occurrence of useful later reflections. The latter help produce perceived space and ambience. The waveguides second advantage over a horn is that the sound is uniform off axis. Swerd mentioning that the sound was equally awful throughout the room (
) was a sign the waveguide portion of it was working well. This does provide a distinct advantage to implementation over a traditional cone/dome setup in that acoustic treatment is far easier to accomplish effectively. With a cone dome with collapsing directivity, the late reflected sound will have a different sonic character and some people are more sensitive than others to that.
I am curious about Swerd's listening to the Abbey's. I have not heard that model, but have heard 2 sets of Summas and I found them to sound more like a small 2 way soft dome speaker than any horn I had heard. They were *very* smooth and very unlike things like Altecs/JBLs and Klipsch that I've heard. That said, I've also heard many people say that the Abbey is a very good performer, as well, so I don't think it's a matter of telling Swerd to go find some Summas. Particularly interesting is that he seems to have heard the traditional horn sound. My experience, which is probably biased by my utter fandom of dynamics since discovering them, with horns seems to mirror what Geddes proposes. Within horns, you have many reflections, all of them would be the "bad" early reflection you try to avoid in your rooms. He calls them Higher Order Modes or HOMs and the geometry of his horns were designed to minimize higher order modes as significantly as possible. The addition of the reticulated foam phase plugs goes a step further in reducing their significance. I went in with high expectations and came away satisfied with what I had heard. Perhaps I deluded myself
into hearing something that was better than it was up front, but I didn't hear anything that made me dislike Altec 511s, Altec Multi-cell horns, smith horns, and others.
As far as coverage pattern goes, vertically, the Summas are a bit limited because of the large center to center spacing between the drivers, but even with the limitations, at 10-12', you'd need to be listening while laying on the floor or standing on a stool before you'd find yourself in a null from the driver interaction. They really work quite well in small rooms. The SEOS actually does a nicer job in this regard.
All that said, waveguides are not the only approach to uniform power response over a large area and I've heard other technologies work quite well. The large curved CBT arrays are really excellent options. Also, I routinely use multiple speaker types, so I'm by no means a horn/waveguide zealot of any sort. I have built probably 200 speakers in the last 20 years of various types and have no issue admitting that each speaker format can work tremendously. In my office at work, I use some tweaked Dennis Murphy designed MBOW1s and wouldn't be without them. At home, I routinely sub in dipoles, electrostatics, conventional speakers, etc, but my fiendish love for dynamics does have me often setting up waveguides or the Unity horns, I built. I have tried a number of other horns, but most drive me out of the room in short order.
