Why are there so few omnidirectional speakers?

[Duke]

@MattHooper, for the record, @Blockader and I do not agree on how much net effect reflections can have on perceived timbre.

An imo relevant nuance that doesn't come up very often is this: We judge perceived loudness by TWO things: The sound PRESSURE level, and the DURATION of the sound.

Sound PRESSURE is the dominant mechanism, but if some frequencies take longer to decay into inaudibility for whatever reason, those frequencies will SEEM to be louder than a measurement of their sound PRESSURE would indicate. This plays a role in perception wherever loudspeaker radiation patterns and their interactions with rooms come into play.

I have my speakers in a room where I have some control of reflections (HF especially) by, for instance, adding diffusers or pulling thick velvet drapes along the side walls. From the listening position I can easily influence the apparent brightness of the sound by altering the reflections. Pulling the drapes along the side wall reflection point will alter the perceived balance to sound less bright, "darker," less airy or strident.

I have some experience with deliberately manipulating the spectral balance of the reflection field (independent of the direct sound) at the loudspeaker itself rather than through modifying the room acoustics, and my observations line up with yours.

 

[oivavoi]

maybe you should read the whole conversation between me and Duke to understand what I was talking about.

Here is a brief summary:

you can influence overall tonality of the system with changing how the reflections are formed inside a room however our hearing is not linear like microphones have. To human hearing, direct sound is perceptually dominant. Speakers with bright direct sound will sound bright no matter how the reflections are formed inside the room. Speakers may sound less or more bright than the direct sound based on the tonality of sum of reflections, nevertheless they will sound bright if the direct sound is bright. As I said before, this is why EQing speakers above the room transition frequency is not recommended. Our hearing is not linear. Our hearing does not sum reflections with direct sound directly and process it as a single information. I recommend you to read the small chapter about precedence-haas effect in Toole's book.

EQ your speakers to have bright direct sound and change the form of reflections inside the room, see if you can make them sound recessed to you than before while facing your speakers.

I think this makes good sense, but isn't it dependent on the listening distance and the direct to indirect ratio in the sound field? Listening near-field and with the loudspeakers somewhat away from boundaries my clear experience is that the direct sound is very dominant. Move just a little bit away, though, and the reflected sound starts to become noticeable, also in my perception of the loudspeakers.

 

[MattHooper]

maybe you should read the whole conversation between me and Duke to understand what I was talking about.

I did read it. I just didn't totally buy all your claims. I mean, you are referencing general ideas I'm familiar with, but I'm not sure your conclusions follow.

Here is a brief summary:

you can influence overall tonality of the system with changing how the reflections are formed inside a room however our hearing is not linear like microphones have.

I know this very well. I do lots of recording.

To human hearing, direct sound is perceptually dominant. Speakers with bright direct sound will sound bright no matter how the reflections are formed inside the room. Speakers may sound less or more bright than the direct sound based on the tonality of sum of reflections, nevertheless they will sound bright if the direct sound is bright. As I said before, this is why EQing speakers above the room transition frequency is not recommended. Our hearing is not linear. Our hearing does not sum reflections with direct sound directly and process it as a single information. I recommend you to read the small chapter about precedence-haas effect in Toole's book.

I'm aware of Toole's work. But I still find the conclusions you deriving don't necessarily follow.

EQ your speakers to have bright direct sound and change the form of reflections inside the room, see if you can make them sound recessed to you than before while facing your speakers.

First I'm not sure exactly what you mean by "making them sound recessed." I'm assuming you mean dulling or dialing down the HF balance?

As I've said, I've essentially done it many times. I alter the perceived HF balance of my speakers all the time by altering room reflections.

My speakers are generally neutral, and they sit in a room renovated with the input of an acoustician. It's a beautiful sounding room but I still enjoy playing with acoustics. I can have a very overdamped room...or a more lively room.

I don't need to EQ my speakers - I can take a bright sounding recording and make it less so, by damping sidewall reflections.

So, yes I see you are referencing known material on psychoacoustics, and I'm well aware of the idea that on-axis frequency response tends to dominate (and as Toole says "we tend to ' hear through' the room acoustics, to some degree). Still, in practice, I find the HF balance easily alterable.

(In fact, recently I put a diffusor behind and between my speakers which has perceptually added more "high frequency" air and brightened up the sound).

 

[Recluse-Animator]

I heard the Innersound Eros several times, and my understanding is that the current Sanders Sound Model 10 is the same concept just refined. It's one of the best small-sweet-spot speakers I know of, in particular with regard to its world-class imaging given good set-up. It will make you roll your eyes at claims of "electrostatic-like transparency" made by manufacturers of conventional speakers.


Maybe keep your eyes open for a used pair? My impression is that they are unusually rugged so a used pair is likely to be in good shape, and the panels can be replaced/upgraded.

Thanks for the input.

As a sick unemployed shit I don't even have money for used ones and even if I did as I don't live in the US the freight and import tax would probably make it cheaper to buy new ones from a retailer in a neighbour country without import tax.

 

[Recluse-Animator]

@MattHooper, for the record, @Blockader and I do not agree on how much net effect reflections can have on perceived timbre.

An imo relevant nuance that doesn't come up very often is this: We judge perceived loudness by TWO things: The sound PRESSURE level, and the DURATION of the sound.

Sound PRESSURE is the dominant mechanism, but if some frequencies take longer to decay into inaudibility for whatever reason, those frequencies will SEEM to be louder than a measurement of their sound PRESSURE would indicate. This plays a role in perception wherever loudspeaker radiation patterns and their interactions with rooms come into play.



I have some experience with deliberately manipulating the spectral balance of the reflection field (independent of the direct sound) at the loudspeaker itself rather than through modifying the room acoustics, and my observations line up with yours.

I'm no expert by any stretch of the imagination, but ill give my two cents.

When people on forums or reviewers ( For example Erin in one of his videos ) show measurements and say "The fr is up 0.5db / 1db at X frequency so it sounds a little bright" I always take those kinda statements with a pallet of salt.
Firstly bright compared to what speakers?
Secondly the room is the biggest culprit making speakers sound bright.

 

[Blockader]

(In fact, recently I put a diffusor behind and between my speakers which has perceptually added more "high frequency" air and brightened up the sound).

Any of my claims do not challenge the possibility of that, in fact the opposite. I am not saying you can't alter balance of your speakers through changing tonality of reflections. There is not only one type of balance for human auditory perception. That is what I'm saying. Our hearing does not directly sum reflections to direct sound like microphones do.

Above room transition frequency, human auditory system can tell the difference between reflections and direct sound. And for human auditory system reflections are not the dominant element in how we hear things, direct sound is. Tonal alterations that apply to reflections can only influence the tonality of reflections, they can't change how we perceive tonality of the direct sound above room transition frequency in a room. While you are facing your speakers, your brain knows which sounds that are arriving to your ears are part of the direct sound and which are part of the reflections. Let's say you bought new imaginary speakers and they have a mid Q +5db peak around 8000hz compared to Genelec 8341. And your speakers have lower sound power response above 8000hz by -5db compared to Genelec 8341. While facing them(as long as the distance isn't very far), your speakers will sound always brighter than Genelec 8341 even if your speakers have same in room response around 8000hz where the resonant peak is. You can't make them sound balanced through ONLY altering tonality of reflections, our auditory perception will always know the difference between direct sound and reflections around 8000hz. You can make reflections sound even more recessed through absorption or what not but what you would hear is then just a direct bright sound with even more recessed reflections. The sum of bright direct sound and recessed HF information is not equal to *balanced* sound basically. This is the essence of why EQd speakers to the same in room target do not sound same.

precedence effect:

the essence of fusion:

 

[Newman]

I agree with what you are typing, but not sure why you bring in Haas, which is all about perceived source or direction the sound is perceived to be coming from? The yellow bit above relates to "dominant" in identifying the direction the sound is perceived as coming from. Not sure it relates to tonality per se.

 

[Newman]

The way I would bring Toole into this conversation, is where he says (Ch 20.2, first edition), "listeners have a remarkable ability to "listen through" rooms and to be able to extract key information about sound sources". He describes how listeners in controlled-DBT tests are able to draw spectral trends - crude frequency responses - describing what they hear in the listening room, and these frequency responses match the on-axis frequency response of the speakers. Not the total ungated response.

When we add this to his already-clear message the listeners invariably, dare I say primarily, prefer speakers with a flat on-axis response, then I conclude that the (quality, experimentally controlled) evidence is that we can't make a speaker that is bright on-axis sound well balanced by muting the treble response of the room walls.

Which puts me in agreement with @Blockader if I understand his essential point correctly in post #50.

cheers

 

[Newman]

What I am not so sure about @Blockader is your claim that omnidirectional home speakers can’t sound tonally right if the studio mixed the production using normal speakers. If the omni speakers are flat on-axis, then for reasons I just wrote in post #68, listeners will perceive the spectral trend as being flat too.

Where omni home speakers will lose out, though, is their degradation of soundstaging ie imaging. Toole is clear on this point and describes them as sound effect generators for people who are willing to sacrifice imaging for boosted spaciousness. All the work that the production crew put into imaging and soundstaging will be largely wasted, and that’s a pity if one is into high fidelity.

 

[oivavoi]

What I am not so sure about @Blockader is your claim that omnidirectional home speakers can’t sound tonally right if the studio mixed the production using normal speakers. If the omni speakers are flat on-axis, then for reasons I just wrote in post #68, listeners will perceive the spectral trend as being flat too.

Where omni home speakers will lose out, though, is their degradation of soundstaging ie imaging. Toole is clear on this point and describes them as sound effect generators for people who are willing to sacrifice imaging for boosted spaciousness. All the work that the production crew put into imaging and soundstaging will be largely wasted, and that’s a pity if one is into high fidelity.

It needs to be said, though, that Toole does not say this on the basis of experimental or systematic evidence. This statement was not in his book (where the content is weighed and criticized by readers before being published), but on this forum. As far as I know neither Harman nor Toole in his pre-Harman days have done much testing on omnis, regarding imaging or other things. The closest one was the half-omni Mirage M1, which was the highest-scoring loudspeaker in Toole's testing in Canada.

I have posted this before, but the little research that exists does not support the claim Toole made on omnis on this forum. Repeating from 2019:

I was debating this - the psychoacoustic "evidence" on preference for or against omnis - at another forum some time ago. When I looked into the research, I saw that omnis have fared very well in all the experiments I could find where an omni was compared to a dipole or a conventional forward-firing speaker.

Flindell 1991 and Bech 1994 were direct comparisons of omnis and other designs (but Bech doesn't discuss it himself, his data were re-analyzed by Evans et al in 2009). In Flindell's study naive listeners preferred omnis, while professional listeners found the omni and the conventional speaker equally good. In Bech's study, the omni and the dipole came out on top.

As mentioned in the thread, the almost-omni Mirage M1 scored higher than any other speaker at the NRC in Canada during the 80s, so much so that dr. Toole chose it himself.

Choisel 2005 did a comparison of a conventional speaker with the Beolab 5, which is semi-omni, with regards to imaging. Beolab 5 imaged as good as the other one. This text isn't available online, but the results are discussed in depth in dr. Toole's book.

David Clark did extensive blind testing in 2010 of three speakers, the dipole Linkwitz Orions, a pair of cheap Behringer monitors, and "The Imp", a DIY quasi-omni speaker by Gary Eickmeier. The outcome of interest was "plausibility of the auditory scene", and the DIY quasi-omni came out on top.

I'm not aware of any other blind test of omnis. As said in another thread, preference testing of loudspeaker designs is not a very big scientific field. But the studies done so far certainly don't indicate that the average listener has any aversion to omnis, when they don't know what they're listening to.

That said, there is sighted anecdotal evidence from listeners that some omnis or quasi-omnis in some rooms seem to have less than stellar imaging. I have experienced this myself, both with omnis and conventional loudspeakers with very wide dispersion. But I have also experienced omni setups which imaged very well. Given the lack of systematic research on omnis, we are basically left with anecdotal experiences and trial and error for those of us who are interested in this type of loudspeaker.

 

[dlaloum]

Sure, but having to place treatment on the wall behind a speaker is more convenient than having them far out in the room if you don't have a dedicated room.
Personally I would still put treatment on the wall even. Even if it was a box speaker I would put bass traps. You can never have too much bass traps.
Ohm doesn't recommend putting any treatment behind their speakers. Even if you have a window behind them they recommend putting it against the wall.

Well it comes down to ones approach to the recording...

If seeking a true high fidelity reproduction of a live acoustic event - something recorded appropriately (eg: 2 mic) - then this type of reproduction is not ideal- the reflections will interfere with the closest possible reproduction of the recorded event.

On the other hand, the current zeitgeist is not for a high fidelity reproduction, but an audiophile one, given 99% of recordings are now substantially artificial, a creation not of a image an acoustic event, but of an artists acoustic intent of an acoustic event (frequently the artist is the mastering engineer here...).

So what we are attempting to reproduce is sonic surealism, or sonic impressionism, or perhaps even a sonic cartoon - in any case the reproduction is not that of a reproduced sonic image.

So the omni close to the wall produces a HUGE soundstage, roomfilling sound effects, much like the 901's you will get a psychedelic blossoming of sound - they do sound fabulous.... and there will be distinct impressions of imaging .... and who is to say what is real and what is not... reality is frangible.

I do love the sound - but find the surrealism of it all, a bit much.... I'm too much of a traditional high fidelity, acoustic, conservative.... sure I appreciate Salvadore Dali, but I tend to prefer a more realist rendition in my paintings! (occasionally a bit of the glow of a Rembrandt can be nice.... Valves...).

Here is a review of the Ohm speakers:

Ohm Acoustics speakers sound bigger than they look

The Audiophiliac gets an earful at the Ohm Acoustics Brooklyn factory.

www.cnet.com

P.S. yes I heard them and other omni relatives, years ago, very much enjoyed their rendition of recordings - but preferred the Quad Electrostatic dipoles...

 

[dlaloum]

Sure, but having to place treatment on the wall behind a speaker is more convenient than having them far out in the room if you don't have a dedicated room.
Personally I would still put treatment on the wall even. Even if it was a box speaker I would put bass traps. You can never have too much bass traps.
Ohm doesn't recommend putting any treatment behind their speakers. Even if you have a window behind them they recommend putting it against the wall.

I think treating the wall behind them basically kills their entire character - those reflections are their "Raison D'Etre" - that is the very reason to purchase them.

There are various takes on omni's - those that place them close to the walls, are seeking a specific effecti, a sort of psychedelic audio - which can be highly addictive...

They can sound fantastic - and it very very much suits those seeking a sophisticated and great sounding lifestyle speaker - so it hits multiple market segments.

Placing them close to the wall, then treating the surface to get rid of the reflections (ie: turning the omni into something it isn't!) - just seems wrong - a waste of money, time and effort - if you don't like their rendition of recordings - find a speaker you prefer.

 

[MattHooper]

Where omni home speakers will lose out, All the work that the production crew put into imaging and soundstaging will be largely wasted, and that’s a pity if one is into high fidelity.

I find that statement a wild exaggeration. I’ve owned omnis, have you? I’ve directly compared my MBLs, in a good sounding room where I have some control over the reflectivity, vs numerous regular forward radiating speakers. All the same information was there. All the images ended up right where they were on regular speakers. Every studio nuance/reverb, you name it. They were amazing machines to hear the details on a recording. If there was the faintest recorded detail or studio effect I heard it.

The MBLs and my Joseph Audio speakers sounded remarkably alike. The main thing being the omnis “disappeared” as apparent sound sources better than any speaker I’ve heard.

Some musicians I know also heard their tracks on the MBLs and they were blown away by how every nuance they put in to the tracks was easy to discern.

 

[melvinjames]

I find that statement a wild exaggeration.

+1 .. I've had my entry-level Ohm MicroWalsh Talls since 2004 and never once thought they lacked in imaging or soundstage, quite the opposite in fact.

 

[Newman]

Sighted listening reports….gotta love ‘em.

 

[oivavoi]

Sighted listening reports….gotta love ‘em.

If you don't like sighted listening reports, feel free to engage with my response to you above which outlines the actual research on omnis

 

[MattHooper]

Sighted listening reports….gotta love ‘em.

That's the lazy attempt at a dismissal.
"Oh, you think you heard that vocalist centered and the guitar to her left on both speakers? And the same reverb applied to each instrument? I'll just dismiss this as your imagination so I don't have to walk back my claim."

If you demand that claims are backed up by blind tests: Would you like to site blind tests that have demonstrated your claim: "All the work that the production crew put into imaging and soundstaging will be largely wasted, and that’s a pity if one is into high fidelity." ??


Please notice you made a qualitative claim - "largely wasted" - not an objective claim. It's a value claim.

You may well say that unless one is listening to The Beatles' music on the exact same monitors in the same room as the Beatles their recording efforts are "largely wasted" because you aren't hearing exactly what they heard. But that would seem to be a rather silly value judgement; neither the Beatles nor most Beatles lovers would say their work was "largely wasted" because people didn't hear things precisely as they did through their monitors. The essential musical and production choices translated through the large variety of playback devices Beatles lovers have used over the years. Now put that in context of listening to a Beatles Track on both a direct radiator and an MBL omni, in conditions optimized for the omni as well, and it's pretty silly to say that the comparison will yield the result the omni sooo distorts the signal "the efforts of the production were wasted." It's a laughable claim, if you've actually done the comparisons (which I have).

In any case, again, having had direct experience comparing omnis with direct radiators, it's easy to place your claim in context.

 

[Recluse-Animator]

(In fact, recently I put a diffusor behind and between my speakers which has perceptually added more "high frequency" air and brightened up the sound).

You have omnidirectional speakers?

 

[Recluse-Animator]

I think treating the wall behind them basically kills their entire character - those reflections are their "Raison D'Etre" - that is the very reason to purchase them.

There are various takes on omni's - those that place them close to the walls, are seeking a specific effecti, a sort of psychedelic audio - which can be highly addictive...

They can sound fantastic - and it very very much suits those seeking a sophisticated and great sounding lifestyle speaker - so it hits multiple market segments.

Placing them close to the wall, then treating the surface to get rid of the reflections (ie: turning the omni into something it isn't!) - just seems wrong - a waste of money, time and effort - if you don't like their rendition of recordings - find a speaker you prefer.

I get you, but treating the wall behind them still gives them 180 degrees of dispersion. Much more than any box or dipole speaker.
If someone's looking for a speaker with that kinda dispersion then there's no other choice.

 

[Recluse-Animator]

As far as I'm aware these are most true omnis as they radiate 360 degrees on both axis.

Morrison Audio: