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Why are there so few omnidirectional speakers?

curiouspeter

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I get that omnidirectional drivers are harder to design and room interaction could be interesting, but it should be relatively cheap to develop speakers using many Class D amplified mini drivers and digital room correction. It will be just like a soundbar morphed into a ball. The $1000 price point should be very doable for a wi-fi speaker.
 

ferrellms

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I get that omnidirectional drivers are harder to design and room interaction could be interesting, but it should be relatively cheap to develop speakers using many Class D amplified mini drivers and digital room correction. It will be just like a soundbar morphed into a ball. The $1000 price point should be very doable for a wi-fi speaker.
Sounds kind of like the BeoLabs that cost 90K.
 

nerdoldnerdith

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I get that omnidirectional drivers are harder to design and room interaction could be interesting, but it should be relatively cheap to develop speakers using many Class D amplified mini drivers and digital room correction. It will be just like a soundbar morphed into a ball. The $1000 price point should be very doable for a wi-fi speaker.
You only need one or two drivers to design a proper point-source omnidirectional speaker. It's about the waveguide. Using many small drivers would make the task more difficult, as the comb filters that invariable results from the use of multiple drivers will detract from the omnidirectional nature of the speaker.

The reason omnidirectional speakers aren't popular is because most of the material to which we listen was mastered for monopole speakers radiating sound toward the listener and nowhere else. The acoustic effect of omnidirectional speakers is very cool with the right music and can be startlingly realistic, but this doesn't translate to movies and doesn't work with most music out there anyway.
 
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curiouspeter

curiouspeter

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You only need one or two drivers to design a proper point-source omnidirectional speaker. It's about the waveguide. Using many small drivers would make the task more difficult, as the comb filters that invariable results from the use of multiple drivers will detract from the omnidirectional nature of the speaker.

The reason omnidirectional speakers aren't popular is because most of the material to which we listen was mastered for monopole speakers radiating sound toward the listener and nowhere else. The acoustic effect of omnidirectional speakers is very cool with the right music and can be startlingly realistic, but this doesn't translate to movies and doesn't work with most music out there anyway.
It should be very suitable for classical and especially orchestral music, which is a huge genre.

With an active design using DSP and software, it is not hard to turn the omnidirectional speaker into bipole, dipole, or directional by turning some drivers. This means it can actually well work for everything.
 

test1223

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The story behind the Siegfried Linkwitz Pluto speaker might be of interest. There are many observations regarding omnidirectional speakers.
Like using an omni speaker as a type of oversized fixed headphone well placed in the middle of a room with very low listening distance. This provides a very good sound but you aren't allowed to move your head.
 

Cars-N-Cans

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I get that omnidirectional drivers are harder to design and room interaction could be interesting, but it should be relatively cheap to develop speakers using many Class D amplified mini drivers and digital room correction. It will be just like a soundbar morphed into a ball. The $1000 price point should be very doable for a wi-fi speaker.
There is the Syng Cell. I think it also has things like beam steering which makes it be able to work, as its name suggests, as a series of sound sources when multiple units are used. Erin also did a review of these a while back, and thought the concept was neat overall. Linus Tech Tips also reviewed them, and wasn't so enamored with them due to their limited functionality if my memory serves me correct. Edit: I think its also a bit consumery in that the bass is excessive from what info is available. For stereo listening, though, pure omnidirectional speakers are a bit antithetical to the objective of getting good spatial imaging since the direct sound that enables you to recover the stereo cues basically becomes nonexistent due to all the reflections.

cell_alpha_full_bleed_03_04-28-2022__3_.jpg
 
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Danaxus

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Not sure, but I'm guessing because they'd sound terrible without amazing room treatment? And most people won't have any, thereby limiting their audience. Just a hunch though, I could be completely off-base (bass - badum-tss)
 
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curiouspeter

curiouspeter

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Not sure, but I'm guessing because they'd sound terrible without amazing room treatment
Or amazing room correction, which is essential for any room and any speaker without amazing room treatment anyway.

Preference.
Most people don't like reflected sound.
Much sound gets reflected anyway even with conventional speakers. Who listens in an an anechoic chamber?
 

Shazb0t

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How many instruments have radiation patterns that are omnidirectional?
 

Sancus

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For an omnidirectional speaker to be usefully distinct, it would need to be evenly omni at all frequencies. Otherwise, it's just a bad version of a normal speaker(and that's probably why they're all pretty bad, as doing this is very challenging).

Most speakers, especially smaller ones, are already unevenly omnidirectional up to around ~1khz.

In an orchestra, sound is omnidirectional though not evenly so.

It's very strange to call an orchestra omnidirectional when many instruments have surprisingly narrow directivity in high frequencies and orchestras sound very different if you are standing behind the wind instruments vs in front of them.

It's well known that the directivity of most instruments and especially the human voice matches up fairly well with monopoles, being omnidirectional at low frequencies and then narrowing at higher frequencies. This is covered in Toole's book.
 

dlaloum

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There are many highly regarded top end Omni or Bipole/Dipole speakers.

Contrary to popular belief (by the Monopole majority) - they can and do sound great, and can do superb imaging - some of them have a narrow sweetspot, others a sweet spot you can walk around in.

They key with these designs is always the room - you have to consider the reflections as integral to your setup - they are desirable as long as they are sufficiently delayed so they don't interfere with the imaging... which means the speakers have to be located far enough from the closest walls to ensure that delay - if that cannot be achieved, then absorbers/diffusers need to be placed on the walls that are too close.

Omni/Di/Bipoles energise the room very differently from monopoles - at one stage I ran a 4.1 all electrostatic surround setup - all speakers were well out into the room, it took a LOT of space - but it sounded fantastic... - the space and the sense of being overwhelmed by large monoliths, ended up getting them replaced with more traditional speakers... but in terms of the sound, I miss them.
 
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curiouspeter

curiouspeter

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For an omnidirectional speaker to be usefully distinct, it would need to be evenly omni at all frequencies. Otherwise, it's just a bad version of a normal speaker(and that's probably why they're all pretty bad, as doing this is very challenging).

Most speakers, especially smaller ones, are already unevenly omnidirectional up to around ~1khz.



It's very strange to call an orchestra omnidirectional when many instruments have surprisingly narrow directivity in high frequencies and orchestras sound very different if you are standing behind the wind instruments vs in front of them.

It's well known that the directivity of most instruments and especially the human voice matches up fairly well with monopoles, being omnidirectional at low frequencies and then narrowing at higher frequencies. This is covered in Toole's book.
The summation of many directional instruments may well produce omnidirectional sound. Strings will be more omnidirectional.

Omnidirectional speakers are probably not best for vocals. They are not movie speakers.
 

Sir Sanders Zingmore

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I‘ve probably asked this before but didn’t understand the answer: I though that Toole et al‘s research showed that speakers with an even off-axis response were preferred. Surely it doesn’t get more even than an omni?
 

dlaloum

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The summation of many directional instruments may well produce omnidirectional sound. Strings will be more omnidirectional.

Omnidirectional speakers are probably not best for vocals. They are not movie speakers.
If the direct sound from the speakers reaches your ear sufficiently early, before the reflections reach your ears (I cannot recall how many milliseconds difference is needed... 5ms?) - then your mind filters out the reflections - you end up hearing the imaging - it can still be pinpoint imaging - and then the reflections arrive and provide the wonderful ambiance - and YES it works very well indeed for Movies.

But - with standard monopoles - you can place them close to the room boundaries (relatively, depending on design) - allowing for a smaller room

With true Omni's, you need at least 2m from speaker to walls in any direction - so you need a very large room
If you have a ballroom ... this is not an issue
For standard homes, it can be an issue - and if due to lack of space, you place them closer to the walls (ie: reflective surfaces) - then you start to sacrifice your imaging - and they become less suitable for Movies as well as Music - imaging and sound location are just as critical to one as the other.

BiPoles/Dipoles can be easier to position, as they are less sensitive to the side walls

Alternatives are to use diffusers and absorbers strategically.... but keeping in mind that the reflections are a positive thing - you want them, but you want them suitably delayed.
 

dlaloum

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I‘ve probably asked this before but didn’t understand the answer: I though that Toole et al‘s research showed that speakers with an even off-axis response were preferred. Surely it doesn’t get more even than an omni?
If I recall correctly... That research included almost no omni's dipoles or bipoles (I think a single lonesome electrostatic panel among around 70 different monopole boxes!)

The room was set up / designed for monopole speakers - so no surprise that the lone bipole didn't perform very well.

And yeah omni's are wide and even dispersion (by definition) - but to get the imaging / pinpoint location that you want for both music and movies, you have to use the reflections properly... and that is far more complicated with an omni than with a monopole.
 

MayaTlab

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With an active design using DSP and software, it is not hard to turn the omnidirectional speaker into bipole, dipole, or directional by turning some drivers. This means it can actually well work for everything.

I'm not quite certain but I believe that what you're describing is the original HomePod, basically (at least on the azimut plane).
 
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