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Originally Posted by
DustinF 
I think my problem is wrapping my head around the waveguide speakers and how they would compare to other designs and what they are meant for.
First and foremost, a waveguide is intended to provide a similar directivity index between the woofer and tweeter, unlike flush mounting. This is true of everything from the wide dispersion waveguide speakers a la Revel and TAD, to the larger stuff in this thread. The SEOS specifically constrains the tweeter response to a 90 degree pattern - that is to say that the sound at 45 deg off-axis is 6db down in level, or something along those lines. The biggest advantage of this 90 degree pattern in a home is that it increases the direct-to-reflected ratio of sound at the listening point - giving a drier presentation that can be argued to be more accurate to the source material. The bigger you go, the further down in frequency you get to push the 90 degree pattern. A 12" two-way - like the Gedlee Abbey - helps keep this pattern down to near 1khz. The biggest advantages of controlling dispersion are seen above 700hz, because this is where not only timbre - but also stereo imaging cues tend to exist.
Large waveguide speakers use compression drivers, some of which allow for a low crossover frequency, which is how you can even use a 12" mid in the first place.
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Other things, like how far do they need to be from back wall, do I need to toe them in (some say as much as 45 degrees). Do I loose the whole point of waveguides if I want 3 up front?
As far as distance from back-wall, that will normally depend on who was designing the crossover. Some like to design with the assumptin that the speaker will essentially sit in a corner, while others don't. I'd say this kind of speaker is certainly less sensitive to placement than a narrow baffle, wide dispersion speaker though.
The 45 degree toe-in is recommended, yes. For a speaker with the correct horizontal polar pattern, it works out in a way that you get fairly equal amounts of sound from the nearest and further speaker - it gives a wide sweet spot. Without toe-in, someone sitting too far off from the further speaker will get a sound dominated by the nearer speaker. Nothing wrong with a center channel,.
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When I look at the osmtm or hitmakers and see a frequency response down to 40hz compared to a waveguide at 55hz, I then wonder if the efficiency of the wave guide is worth it. Or would I enjoy the sound of the other speakers? I guess I'm just looking on opinions on what to buy for music and tv. I really liked what I've heard about both the osmtm and the hitmakers. I also like the size of the 8" B&C.
On of my favorite speakers is a little 4" bookshelf that probably doesn't even go usefully below 70hz. Small speakers can sound great within their limits. But those limits exist, plain and simple. No subwoofer can correct for it nor can a big amp can correct for it. Efficiency and displacement just aren't there. Without efficiency, you run into thermal compression. without surface area, you run into over-excursion. These are real and audible.
Personally I do like for a speaker to get down to 100hz without the need for a vent. Below that, multiple subwoofers have real advantages.
The thing you need to realize though is that frequency response is "shaped" by different things. The crossover, and also the mechanical properties of the drivers. It may seem difficult for a speaker with a 12" midwoofer to fall off in frequency, but even that can be misleading. For a vented speaker, equalization above the tuning frequency is harmless if the headroom is there, so focus on the tuning rather than the F3. The 12" woofer has a LOT more headroom than a 4" or 5" woofer.
