CDC,
Regarding omnis and added reverb.
You could look at this another way: Every speaker is an omni.
For signals below 150hz or so. So called "Omnis" merely continue this radiation pattern throughout the audible frequency range. From this viewpoint, your question should read:
"What happens to the intended reverb on a recording when you effectively remove that intended reverb by restricting the radiation pattern above 150 hz?"
It is your phrasing that begs the question. There is no "default" reproduction dispersion pattern - unless you believe that the recording was intended for replay in a specific environment. That's because every room impacts the response of every speaker system differently, with a single commonality: There is - generally speaking - an increasingly destructive impact as frequency drops into the bass range, where all speakers provide omnipolar dispersion. Bummer.
As to my opinion of "waveguides", the phrase is used in many ways, so it's hard to respond. I assume that you mean a (truncated) horn, as this is IME the most common usage. My (rather limited) experience here is pretty similar to that for other designs. Zingalis - which I own - sound different from SAP and Avantegarde, the two other horn systems with which I'm rather familiar. OTOH, the later two are full blown horns, rather than truncated "waveguides" so we may not be talking strictly apples to apples here.
Like the broad similarities in imaging between omni designs, I would note that different horn/waveguide designs can share the ability to mitigate damage from difficult rooms or difficult positioning in better rooms. The effect of this (obviously) varies from room to room. In a well designed room, it may prove either beneficial or disadvantageous - or both, varying with your program choices.
Beyond that, I'd say that these designs vary as widely in overall tonality as most other designs. If your room presents issues, then find a speaker with appropriate restrictions to dispersion. This might mean a waveguide/horn or maybe a planar design with little output to the sides. Just recognize that this doesn't mean that such a design will be superior in a different environment. Horses for courses, you could say.
And, either way, you have to then find an example that works for you tonally.
Again IMO and IME.
Marty
