Omnidirectional speakers. The future?


I have been interested in hi-fi for about 25 years. I usually get the hankering to buy something if it knocks my socks off. Like most I started with a pair of box speakers. Then I heard a pair of Magnepans and was instantly hooked on planars. The next sock knocker was a pair of Soundlabs. I saved until I could afford a pair of Millenium 2's. Sock knocker number 3 was a pair of Shahinian Diapasons (Omnidirectional radiators utilizing multiple conventional drivers pointed in four directions). These sounded as much like real music as anything I had ever heard.
Duke from Audiokinesis seems to be onto the importance of loudspeaker radiation patterns. I don't see alot of other posts about the subject.
Sock knocker number four was a pair of Quad 988's. But wait, I'm back to planars. Or am I? It seems the Quads emmulate a point source by utilizing time delay in concentric rings in the diaphragms. At low volumes, the Quads might be better than my Shahinians. Unfortunately they lack deep bass and extreme dynamics so the Shahinians are still my # 1 choice. And what about the highly acclaimed (and rightly so) Soundlabs. These planars are actually constructed on a radius.
I agree with Richard Shahinian. Sound waves in nature propagate in a polyradial trajectory from their point of source. So then doesn't it seem logical that a loudspeaker should try to emmulate nature?

holzhauer
I have always grooved to the sound of wide-dispersion speakers. I grew up in a household where my father's final listening room speakers were a pair of classic Allison: One towers, with their V-shaped front baffles that sported a dual compliment of their ultra-wide dispersion dome midranges and nipple-shaped tweeters angled 45 degrees apart, and whose flat backs were designed for on-front-wall placement to achieve a virtual infinite-baffle loading of the speaker/room interface. Although they didn't compete with today's speakers in terms of resolution and precision, their presentation was a kind of aural widescreen that energized the whole room to a degree (and even at low volumes) which you just don't hear from most speakers. I'd love to hear the new iteration of this landmark 70's design that was brought out a couple of years ago with renewed involvement from Roy Allison...

I find the sound of dipolar panels like Maggies, Soundlabs, etc. very attractive, until you try setting them up in a realistically-sized listening room ; conventional box-style monopolar radiators are just plain easier to place and extract optimum sound from in many instances. Bipolars can be another story becaue you don't run into as many phase-related difficulties, but I've never been overly impressed with most of the designs I've heard that achieve this radiation pattern through the use of separate, opposed drivers. Maybe something more along the lines of designs like the MBL Radialstahler, Ohm Walsh, or that forthcoming B&O superspeaker, which radiate through 360 degrees from single drivers lacking vertical baffles.

BTW, although I can like the sound of bi-, di-, and omni-polar speakers, I don't necessarily agree with the 'live music' argument against monopolar speakers in theory. Yes, live music is radiated in all directions (although not equally), but I don't view this as being directly analogous to the home playback situation. I am philosophically of the 'you are there' school, as opposed to the 'they are here' school. To be 'there', it is a good idea to minimize the reverberant contribution of the listening room to the reproduced acoustic, which means controlled-dispersion speakers. I see the job of the loudspeakers as being not the inverse of the original musical instruments and performers, but as the inverse of the microphones which recorded them.

The end result is that there often seems to be a sonic dichotomy between the sense of envelopment and presence, whether 'correct' or 'artificial', that you can get from speakers which directly radiate to more than just the frontal direction, and the sense of precise focus and scaled perspective you can get from monopoles. Both have their virtues, but in my listening rooms monopoles have always been the practical dictate. My present choice of Thiel speakers represents a monopolar design having wide dispersion for the breed with very even off-axis response tapering (at least in the horizontal plane - improving the vertical plane uniformity would seem to be one advantage of Thiel's newer coaxial designs) and a low-diffraction cabinet. Actually, I'm not sure that my idealized speaker design wouldn't be a monopolar line- or point-source, the former of which is represented by the Wisdom closed-back narrow planars, and the latter by the Cabasse tri-axial 'eyeballs', neither of which I've had an opportunity to hear, to my sorrow (not that I could really afford 'em anyway). Of course, one could always try installing a pair of Quad ESL's into a wall that's been cut-out to form a simulated infinite-baffle between two relatively small listening rooms...
omnidirectional is without a doubt the best kept secret in home audio. shahinian,allison,gradient,and ohm and a handful of others are still the closest thing to the real thing from bottom to top. they will always be a cult item because they are out of step(and hard to design)with what most hi enders want.
sean...To be precise, the wavefront generated by the original Ohm speakers is cylindrical, rather than spherical.
Lack of vertical dispersion is a good thing when the speaker is used in a room with ceiling and floor to make reflections, and is a characteristic of line arrays, and of the ubiquitous MTM driver configuration. Even so called "planar" speakers resemble line arrays because (Quads excepted) they are taller than they are wide.

More on point sources...the musical instruments are not points, but the microphones that make the recording are. I regard the microphones as "sampling" the planar wavefront of the original sound. Now, when you play back the recording using a point source loudspeaker, the loudspeaker sound radiates outward again forming a spherical (planar) wavefront. However, with a point source speaker the radiation process starts over again from a point, with SPL falling off rapidly with distance, whereas a planar speaker generates the wavefront as it exists at a distance from the source where it has already expanded, and so there is only slight variation of SPL with distance from the speaker.

Speakers of all descriptions can sound good in certain situations (even horns and ported boxes). In fact I have even heard the original Bose speakers sound pretty good with the right setup and kind of music. There is more than one way to skin a cat, which we all agree is a good thing.
As I see it progressing we'll be able to construct whole rooms that can transmit sound from any location to any location and only to that location. That way multiple listeners from any point in the room will hear the same as any other. Supermarkets are already working on part of the technology. What they do is have one speaker with very limited dispersion beam sound only to a specific location and only someone at that location can hear it like in front of the taco section and you hear an ad. Not sure I'm explaining it sufficiently to do it justice. But imagine what a movie might sound like with a whole room that is the speaker(s).
Fine posts, all. I designed my first speaker system as an omni (vertical-radiating planar?) back as a teen in the late 60s, using a Utah triaxial driver sitting upfiring into a plaster-filled kitchen funnel mounted in a wooden "basket", the whole thing sitting atop a 90 lb clay suwerpipe! Yikes. Antiresonant, anyway. A couple of visits to Tweeter, Etc. caught me hearing the new small Mirage Omni-whatevers. My gosh what horrible sound. The sales staff at both locations hate 'em too. Sigh....
I proposed to a good friend/master acoustician the idea of collaborating on an omni-design someday, and he asked why? as they don't work right in normal living rooms. Can't remember his primary concerns (maybe indeed the "primary" early arrival/reflections summation stuff). Happy Holidays all.