Omnidirectional speakers. The future?

Ohm has been a proponet of omnidirectional sound for years...there probably are others as well...as for the future...only the market will tell...

Doesn't Bang & Olufsen have something new in this area? The little buzz I've heard suggests it is legit audiophile stuff, not standard B&O fare.

I would love to hear a pair of Shahinians sometime, but you have to go to Long Island to do so.

The "point source" thing doesn't really make sense if you think about it. Most instruments are pretty big points. Furthermore, even if the instrument were a solo kazoo, its sound would propogate as a spherical wavefront, and after traveling 30 or 40 feet, this wavefront would be nearly flat. A planar speaker can best regenerate this wavefront.

While the Shahinian's are nice speakers, they really aren't "Omni's" so much as they are multiple radiators arrayed to produce a diffuse pattern. Any time you use multiple drivers, you run into lobing problems due to cancellation, etc... While i hate to bring up a bad word and make yet another comparison to this company, Bose 901's are as much "Omni's" as Shahinians are. This is NOT to compare Shahinian's to Bose, as i have a lot of respect for the Shahinian's and very little for Bose.

Having said that, "true" Omni's* that radiate from a point source ( single driver ) have some very specific problems with them. Most all are spl limited and lack dynamic range. If you can live with that, they can do some truly incredible things at low to medium listening levels. On top of this, their placement will be different from what is optimal for most front firing designs, so this should be factored in before shelling out the cash.

The only "point source Omni's" that i know of are the speakers from Ohm Acoustics. I'm specifically referring to the Ohm A, Ohm F, Ohm G with the G kind of "half in / half out" of that category. This is due to using a passive radiator to reinforce the low frequency response, producing two distinct points of radiation. Since it is not an active driver though and primarily only contributing sounds at low frequencies as it is passively excited, we'll let it "slip by".

The other "Walsh series" speakers that Ohm uses do not use "real" Walsh drivers in the classic sense and are not really omni-directional in nature. These would fall more into the "diffuse radiator" category like the Shahinians. Having said that, they use a very different approach from both the Shahinian's and their namesakes, the A, F and G.

The others that i would consider "Omni's" are the MBL Radialstrahler's, the German Physik's speakers and the Huff's, which use German Physik's drivers in their own proprietary designs. The difference between these "Omni's" and the Ohm's are that the Ohm's are a point source ( single source of sound radiation ) and cover the full frequency range by themselves. The others mentioned above make use of some type of active assistance ( woofers, sub-woofers, etc.. ) in conjunction with the Omni drivers being used for the mids and treble. As such, they have two very distinct and different types of radiation with the associated differences in presentation taking place. Obviously, this is only my opinion, so take it for what it is worth.

As i mentioned in another thread, i really like my F's. I liked the first pair enough after becoming familiar with them to drive to Boston to pick up a second pair. Part of the problem with these and / or any other "esoteric" driver is the lack of support for them and the potential for damage when shipping. Due to the exposed radiating surfaces of these drivers, any type of puncture to the shipping carton can be fatal. On top of that, when the Ohm's ( in specific ) suffer from foam rot due to age, the mass of the cone is hanging strictly from the spider ( the corrugated orange, yellow , tan looking thing behind the cone and in front of the magnet ). Since it is unlikely that you'll find someone locally to repair these ( unless you live in a big city ), you'll have to ship them. With the lack of support from the foam being eaten away, the driver is now slapping the voice coil around inside the magnet as it is moved, producing further possible damage. On top of this, the spider becomes even more stretched out, causing a reduced amount of control of the driver due to a weaker suspension. As such, if you are planning on buying something like this ( or any other exotic speaker ), you better make sure that you can transport them safely AND know where to go should you need to have them repaired.

I could go on and on here, but i've already got one thread where i've said too much going right now : ) Sean
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*Omni's are not really "Omni's" in the fact that most all of them suffer from limited vertical dispersion characteristics. Obviously, "omni" means sound distribution to all directions in an even manner, but due to the limited vertical and horizontal radiation of most other designs, even these "limited vertical radiators" are FAR more "Omni" than most. Omni's should not be confused with Dipole's ( E'stat's, Planar's, Ribbon's ) or Bipole's ( speakers with extra drivers firing out of the rear of the cabinet ) as they are quite different in radiation characteristics. The rear wave coming out of a dipole is out of phase with the front wave whereas a speaker like those mentioned above radiate the signal in all directions horizontally in phase. Bipolar speakers, i.e. those with rear mounted tweeters, mids, woofers, etc... have the front wave and rear wave in phase with each other, but because there is nothing joining the signal as it wraps around the box, these too will produce cancellation when the waves "collide". Due to the continuous radiation of an "omni" driver on all sides, the sound from the driver itself is produced in phase, so there is no cancellation. The only cancellations that do take place are from room reflections, which become even more of a problem. Since you have sound going in EVERY direction in a rather uniform manner, you've got a lot more points to reflect off of. That is why i mentioned different placement within rooms, etc...