Omnidirectional speakers. The future?

Hi Billhound,

In general, a large room is desirable because it introduces a greater time delay between the first-arrival sound and the onset of significant reverberant energy. This is probably more true for directional speakers than for omnidirectional ones, but both types would probably benefit from a large room in this respect.

The larger the room, the more the power response (summed omnidirectional response) tends to dominate the perceived tonal balance. This is because as you move farther away from the speakers, the loudness of the direct sound falls off more rapidly than does the loudness of the reverberant energy. With conventional speakers, the tonal balance is likely to be audibly degraded once you move back far enough for the power response to dominate. With omnis or other consistent-pattern speakers, the tonal balance will hold up better in a large room.

To given an extreme example, once upon a time I hauled my then-pair of big home-brew speakers (1" tweet, 7" mid, two 15" woofers) to an informal dance held in a church's activity room. To my shame and horror, my beloved behemoths sounded sluggish on bottom, harsh in the mids, dull on top, and overall quite fatiguing. I was mortified, as I'd been letting the locals know what a kick-butt speaker builder I was. Now I understand that those were the wrong speakers for that application, as the power response totally dominated the perceived tonal balance in that large space and their power response was quite poor, having never been given a second thought by their designer (ahem). That's why people use horns or horn/woofer hybrids at dances - they have a much better power response, even if up close and in the "sweet spot" conventional speakers would sound better. High output omnis like the Wolcott Omnisphere also work well in this sort of application.

Getting back to your 1600 square foot room with 16 foot ceilings, I would definitely argue in favor of a speaker that generates a tonally correct reverberant field over one that does not. You may or may not prefer a very wide-pattern speaker like the Shahinians; if you do, they'll sound great in there. In a medium-wide but still consistent pattern speaker, you have full-range planars like the Sound Labs and big Maggies, and dynamic dipoles from Gradient and Audio Artistry. If you like a narrower pattern speaker, then for a large room you might consider horn-based systems like the offerings from Edgarhorn, Classic Audio Reproductions, eXemplar, Pi Speakers, Zingali, SP Technologies, and the Klipsch Heritage line. [disclaimer - I sell two of the brands mentioned here]. But dealing with a 1600 square foot room with 16 foot ceilings is a nice problem to have.

Well, them's my thoughs.

Duke

Billhound,
1200 s.f. is absolutely huge. about as big as my whole house. I'm listening to my Shahinian Diapasons in a 12x15 room with 9 ft ceilings and they sound great- wicked bass node however. I know Richard Shahinian has his Diapasons set up in a very large room with high ceilings- kind of a factory type setting from what i have been told. By all accounts his setup sounds spectacular.
They must sound pretty darn good outside as well. A fellow by the name of Carl Salerno who used to sell Shahinians near Kenosha Wisconsin had a pair playing outside of his home on Lake Michigan. The neighbors stopped by thinking he had live musicians in his back yard.
The Diapasons have massive power handling. something like 800 watts I believe. These things really can approach the energy created by a live band.
As far as the reflective walls and floors go, I would suspect this room could have problems. Rooms that are too highly reflective can be a pain. In my experience, if peoples voices become muddled due to all the reflections, then your speakers are going to have problems also.

Hi Guys, Just dropped in to see this thread still going.

Lot of interesting ideas floating around, but the concept of "dispersion" mimicking instrument size, or cone size making an instrument sound larger is slightly off the mark.

Must be a visual thing. That is, we are comparing it to how we "see" things.

That is not how recorded stereo sound works at all.

Recorded sound is more like a three gun projector that has three beams that have to be perfectly converged to form a visual image. In the case of stereo, it is two "sonic projecting guns" that have to be converged to form a sonic image for the ear brain.

It the "projectors guns" are diffused and dispersed, the visual image is blurry and washed out. If they are clear and focused, they form a highly resolved and detailed image on the screen.

Wide dispersion from a speaker does not have anything to do with the way you hear it unless your ears are 3 feet wide on each side of your head.

Spreading the sound out 90 degrees, 180 degrees or 360 degrees, will not cause it to sound like the real instrument since your ears only sample TWO "very small" samples. And that image is formed by sampling 2 signals that combine to make the image.

The illusion or "confusion" is related to perceiving that we somehow hear recorded sound from stereo, as we do a live event.

We don't.

In real life, we have millions of sound sources coming in from any and all angles. In stereo, we have 2. Trying to make (disperse) the 2 into that million is not only futile, but impossible.

This is an attempt to "disassemble" the two signals, by sending them all over the place to somehow be reassembled at you ear.

Taking these two samples and trying to make them disperse into some sonic spray, and expecting that this spray will then gel into a soundstage, won't happen.

Now don't get me wrong, it can sound beautiful, but it really won't do what most are thinking.

The Bose 901s developed by Dr Amar Bose in the late 60s, tried to perform this by firing all that info into a reflective surface (wall) and using that dispersion and about 17-22% direct sound to give the mirage of a "sonic projection with direction".

Few use them any more.

Regarding Anechoic Chambers.

I have built and used many anechoic chambers, and was thinking at one time about building a small 7' x 7' x 6' chamber to sell to audiophiles who might find them fun to assemble and use in apartments or other applications where they wanted to listen at concert levels, without disturbing neighbors or whatever.

They could be placed in large closets, garages, basements, attics or where have you and the sound would be unbeleivable. Even modest equipment yeilded some very impressive, realistic, listening.

The sonic virtues of this type of listening has not been experienced by many, and I can only say the you can place yourself into a live recording far deeper than any other listening environment.

I have been there many times. I currently use a "modified" LEDE type room which also works well for most purposes.

Don't make the mistake of visiting JBL or some speaker company's chamber, (designed to measure speaker sound only) and think you know what anechoic listening really is.

But in any event, I just wanted to "sound off" on the dispersion issue. The point being that any dispersion any wider than your ear is not used in the ear/brain recreation, unless it has hit a surface and becomes a reflection, and then as someone else has stated it is a "distortion". A distortion is any thing other than the original signal that has be added to or subtracted from the original.

In the standard listening room we probably have a "very high" % of reflected sound/distortion. I mean it could be 40% or so. Imagine buying an amp that had 40% distortion!!

And as a final thought, many seem to read the scientific literature written by well respected Acoustic Engineers and researchers and "mis" interpret the info, and worse yet many well credentialed Acousticians,and experts do the same thing.

While physics and acoustics are "in stone" as to their properties and principles, their applications to venues and reproduction environment are "VERY" different.

The largest and main difference is that in a "performance venue" the space is designed or treated to "USE" the environment. Devices like diffusors and such "are" valuable to acheiving a good even covering of the original space.

In the "reproduction environment" that is not the case.

Anyone who confuses the two will never hear what is on the recording from the original venue.

Again, this is not a problem if you like the "sound shaping" you are doing. I certainly used to.....Until I heard about 90% of the real thing, and I haven't been the same since (OK no jokes)

I hope that all makes sense, and I also trust that those who are ecstatically happy with their sound do not take offense. It is just physics and acoustics, and beleive it or not, you're as much an expert as the next guy, cause you know what you like.

And that is what counts.

Bose 901's are based on 11% direct vs 89% reflected sound. Unless one is standing completely off axis and slightly around a corner from where the performance is taking place, those ratios are highly unlikely to be anywhere near accurate during a live listening session. The fact that Bose based most of his findings on measurements taken while sitting underneath the overhang of balcony seats may explain at least a portion of his findings. Why someone would use that specific seating location to conduct those types of tests is beyond me though.

As far as binaural recordings go, i mentioned this type of presentation working phenomenally well with Omni's much earlier in this thread. I've commented on this type of recording technique over at AA in the Pro Asylum quite some time ago. When Alan Kafton of Audio Excellence / Audio Dharma cable cooking asked about various methods that could be used to record small ensembles in a nightclub, that was the first technique i told him to try. It is minimally intrusive in terms of set-up and operation and can provide a very natural presentation, both in terms of spatial cues and tonal balance.

As a side note, i used to use this technique when recording bands for "demo's". Not only is the sound "live" i.e. not nearly as manipulated as is done with dozens of mics and processing, it is also lower in distortion ( less microphone overload ) and much closer to what one would actually hear at a show. If a band can sound good on stage without a bunch of multi-track gimmicks, the talent scouts working for record companies know that they can be made to sound "even better" in a studio. The reason for that? They have all the knobs and gadgets required to "make magic happen". At least, so they think. A high quality binaural recording is pretty hard to match in terms of natural sonic qualities. The one major drawback is that it will not sound as "detailed" or "image specific" as an electronically manipulated presentation using dozens of up-close mic's and tons of bells and whistles in the recording chain.

As far as using the "true" Walsh type Ohm's in a huge room, i've never tried it. Their bass output may be up to the task, but they simply can't move enough air to fill the room with sound. That is, they are SPL challenged due to "warbling" i.e. highly audible amounts of Doppler distortion once you hit a certain volume level. With this type of design, there's no way around that problem. Sean
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Thanks very much for your thoughts, guys.
My space is indeed houselike in scale- it is my live/work
space. I live in an open loft in what was at one time a
commercial building. Possibly something similar
to the factory-like space that Holzhauer describes in
Mr. Shahinian's set up. Unfortunately, Diapasons are
not in my budget. I wonder how one of their less pricey offerings might fair in an oversized space. Its a pity that Shahinians and other omni-like offerings are impossible to demo before purchase- I like to avoid expensive leaps of blind faith when I can.

I do not expect any speaker I might buy, omni or not, to energize my whole space. I just want to hear great music in a 'designated' listening area. Because of my flat out ignorance when it comes to the science of acoustics, I wasn't sure if that's a reasonable goal or not. Omnis intrigue me because I wonder if they could create this hypothetical 'sweet area' in my space as well, worse, or better than conventional designs.

My ignorant gut says there may be advantages to omnis in my situation since they are designed in part to depend on room interaction. While I will end up doing a few things in here to try take the edge off all the high reflectivity, I dont intend to invest time and money in a complete high end sound treatment, or carve up my space into rooms. So, since my envrionment will inevitably have some significant interaction with whatever sound system, why not go with speakers designed to interact with their environment in the first place? Hence my interest in omnis.

Audiokinesis provides a well reasoned and knowledgeble articulation of that idea, which was really only a hunch for me before I read his helpful post- thanks.

In trying to understand how omnis and omni-like speakers work, I find Holzhauer's report that the diapasons sound great outdoors counter intuitive. Since the system is designed to interact with its environment, I would have imagined that removing walls and ceilings, (i.e. setting them up outside), would actually make the speakers sound bad, or at least significantly different than the designer intended. Maybe I understand this stuff even less well than I think I do.

Many have pointed out that omni's cannot reproduce the actual sound of the recording due to simple physical law.
Again, while I have no training in acoustics, the reasoning sounds correct to me, and its great to have a peek into the actual science of it. As they point out, this does not necessarilly indicate that they sound "bad", unless one's goal is a strictly truthful representation of the recorded event. I know that's supposed to be a goal of hi-fi, but I don't fall into that camp, if for no other reasons than practicality and cost. Even in set ups where price is no object, I bet there is still acomodation made by the listener for the sonic 'white lies' that inevitably slip in through the door along with the strictly accurate sonic 'truths'. I'm more interested in a balance between euphoney, accuracey, and price.

In the end what sounds good is such a personal question, that I lament again the problem of not being able to demo most of these omnis up front. While a store demo wont tell how a speaker will sound at home, it will at least give a clue. That's one reason I'm arbitrarilly deciding not to consider horns. They might do the trick great, but they seem to be as difficult to find as omnis, and it would be nice to actually start listening to something soon!