Mapman, The pure Omni's are designed to propagate a signal in a 360 degree circle so when you are listening to them you are hearing a small direct signal (think of a 'point source type speaker' listened to in the near field which excludes most of the reverberant sounds from room surfaces). In addition, you are hearing all of the reverberant sounds arriving at different times depending on the distance they will travel. Great atmospherical potential hear. And one of the reasons that some of the manufacturers claim that they are great with large orchestral music, but few claim that they are great for solo vocals. Actually the direct sound with an Omni is a minor component of the sound field.
Omni'his, well executed, will give a great 'sound stage' effect. It will fill your room and you'll be happy to some degree anywhere in the room. But in the final anyalysis all of the reverberant energy will blur the direct signal and obscure any real holographic imaging.
Think of my analogy to a live person 50 ft away clearly recognized as such compared to a life sized and colored paper cut out. And then in a fog you can't tell one from the other.
To a lesser degree than Omni's, you have the same issues with panels and electrostats. Some of the electrostats and panels (I have both types in the closet) have developed a manner of shaping to signal to enhance the sense of focused imaging, which make the principle sounds real life size (like vocalists in particular) and maintaining a big sound field.
But, as you have probably guessed, the better the sense of focused imaging the more they lose the sense of a huge airy sound stage. I believe, like my panels and electrostats, Ohm's latter designs (after the F models) went from 360 degrees to a speaker which reduced its off axis energy to reduce the amplitude of reberberated energy and enhance the on axis signals. I could be wrong.
That is one of the reasons some folks want speakers which can produce sharp pin point imaging and take great care in setting them up to minimize reverberant energy - then you hear what is in the pits and grooves with out added room effects, at least to the extent that you can, or wish to exclude them. Some folks like near field listening which takes out most reverberant energy, especially when you deaden the 1st reflection points on the sides, the ceiling, the floors, and the wall behind the speakers. Needless to say, but I will, a lot of folks don't like this sound. But it is exactly the circumstances that allow the creation of sonic holography.
I hope this makes a bit of sense to you. But the bottom line is you really have to hear what I'm talking about. It is hard to describe. But, what the hell - here goes.
About 20 years ago I went into a retail shop near Berkley, Ca. They had a small listening room which contained Theil 4a's, powered by Threshold SA2's, driven by a CJ5 pre amp, an Oracle TT and I forget the cartridge. They played Opus 3's "Depth of Image". One cut has a group of guys playing pan flutes and drums (the flutes are a toughy). Anyway in the middle of the cut they flubbed up the flutes and broke into a brief conversation. I kid you not, the talking was so realistic that I felt you could easily walk into the middle of the group and join them. Replicating this experience has occupied me ever sense. I think I'm as close as I can get in my present environment with my current stuff, but I ain't there. Yet! :-)
The thing that makes this subject difficult for many, I think, is that most folks have not heard a really holographic imaging system with appropriate recordings (often very minimally miked recordings) and confuse great soundstaging from holographic imaging. I know I didn't until I heard one.
BTW, if you have any doubt in your mind about what your system is capable of, get a recording from Opus 3. They did a series of 'test' disc's one of which was called "Depth of Image" and another was "Timbre". They were originally on LP's but are now available in a compilation of CD over the internet.
These recordings are compilations of several recordings put out by Opus 3, from solo vocalist, solo instrumental, small bands, small jazz groups, large jazz orchestra, etc. Forgive the fact that they are all Swed's. Each cut will have a description of what you should hear. If you don't hear what the cut sez, you have work to do. It is all there. Some of the cuts are excelent for resolving (or at least identifying problems in your system. For example, a recorder playing in its high registers. You get that right and you have a fine HFR - get it wrong and your ears will bleed. I highly recommend these recordings for set up and equipment evaluation as well.
Hope that helps a bit.
