Which speakers have wide dispersion?
In one of the earlier threads reference was made to omni directional speakers sounding better due to the wide dispersion and that is the key to their signature.
Obviously this affects required room dimensions, is wide dispersion the way to go?
It depends on what is important to you. If you have a private, set-aside listening room where just you and a few companions can listen in a tightly defined sweet spot, then a narrow dispersion speaker or dipole flat panel (which takes the side boundaries out of the equation) would be desirable. Properly set up, this type of dispersion pattern lends itself best to the "palpable, 3D imaging" where the voides and instruments seem to hang spookily in 3D space. It's pretty difficult to achieve this type of 3D imaging with any other approach that I know of, but there are disadvantages: 1) It's totally picky about speaker placement, seating location, and room treatments to take room boundary reflections out of the equation 2) The sweet spot is narrow, and you often get a big drop in fidelity by standing up or moving more than a foot or two from the sweet spot; 3) It's not a very sociable setup; vocal and instrumental timbres will probably be off in one place or another (e.g., a "cupped hands" midrange) when listeners are too far out of the sweet spot.
Wide dispersion, esp. hemispherical or omnidirectional speakers tend to throw a wide, realistic (or sometimes over-sized, depending on the speaker and the room) soundstage, and eliminates or reduces many of the disadvantages mentioned in the previous approach. They make for a better "party speaker" or for listening when you are doing housework or otherwise can't sit in the sweet spot. Because omni's energize the room more like real instruments and voices, there is a truth to the timbres in just about any place in the living space. While placement is important, it is seldom as critical as the dipole flat panel speakers and the ones with limited dispersion with time-aligned drivers. The one disadvantage with the wide dispersion speakers that intentionally bring the room into the mix is that--while they often throw a realistic-sounding soundstage with an excellent sense of depth to this soundstage, they cannot achieve the "palpable 3D imaging" to the degree that you can achieve from the other approach.
For me, 12 years ago I was in the market for a new pair of speakers, and I was seriously considering the approx.$2K Martin-Logans, the Magnepan 2.7s, or the bipolar Mirage M5si's. Given that I had 2 dogs, 2 young children, and a family situation where getting to the sweet spot was going to be an exercise in frustration, I elected to go with the wide dispersion Mirages, and have never regretted it. You might say that the bipolar, omnipolar, and omnidirectional speakers have a more resilient soundstage. You get a stable soundstage and accompanying frequency response just about wherever you go in the listening area. Timbres sound true to life because the speakers interact with the room much like voices and instruments do. The only thing you give up is that last bit of pinpoint imaging, which I think is an artifice you seldom hear in live music anyway.
