Omnidirectional speakers

[Purité Audio]

Omni's are intrinsically wrong, some half baked idea to replicate a live orchestra, good for parties though.
Keith

 

[Cosmik]

During beat count-down and drum sticks calling time at the very beginning of the song, there is a comment by the guitarist. You can hear that on better systems, with the same mix, but can't hear it on less resolving systems.

I wonder if "resolving" might boil down to the difference between omni and directional..? In terms of absolute details, added 'ambience' from the room would be more likely to mask the guitarist's comment than if you were listening in an anechoic chamber. I tend to think that it is a (fairly non-critical) balancing act between an overly dry sound for an extremely directional speaker system, and an overly 'wet' sound for omni, depending on the room furnishings etc.

 

[Blumlein 88]

Omni's are intrinsically wrong, some half baked idea to replicate a live orchestra, good for parties though.
Keith

Maybe reproducing music indoors is an idea not even half baked. Perhaps Omni sources outdoors is the holy grail and then some. How much easier things would be if not for the room effects. Real audiophiles don't listen indoors?

 

[oivavoi]

Omni's are intrinsically wrong, some half baked idea to replicate a live orchestra, good for parties though.
Keith

Maybe reproducing music indoors is an idea not even half baked. Perhaps Omni sources outdoors is the holy grail and then some. How much easier things would be if not for the room effects. Real audiophiles don't listen indoors?

Ok, I'll put forward the main things I think can be good with a well-implemented omni:

1) If dispersion is indeed 100% even in all directions, then the reflections which arrive at the listener will be much more similar to the direct sound. Assuming that one listens in a living room and not a room with thick absorbers/diffusers all over, this is a good thing.

2) Assuming one sits in reasonable proximity of the speakers, the Haas effect will lead us to perceive reflections as part of the direct sound (especially if they are similar to the direct sound)

3) Omnis have a dispersion pattern that is closer to how sound emanates from live acoustic instruments and musical groups. If I perform a concert with my choir, together with a small string ensemble for example, I can typically walk around this ensemble in a circle, and I will feel that the sound is coming towards me from every point in the circle. It also doesn't matter whether I sit down or stand up, there is no big change in the sound that radiates towards me. The only speakers which are able to recreate this are omnis, and to a certain degree CBT style speakers.

4) And then of course, it's listening outside the sweet spot, or when there are more people in the room . Here omnis hold great advantages, together with CBTs again, multi channel systems, and hugely oversized horns that fill up the entire room with sound.

EDIT:
5) One more point: I belive that room reflections, when done right, actually can create an even better stereo illusion and sound stage. But with omnis, room acoustics obviously become very important, and they probably won't work at all in small rooms.

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Taken together, I think this goes a long way towards explaining why there are quite some listeners who perceive omnis as more "realistic" in the way they recreate music than conventional forward-firing speakers.

 

[fas42]

3) Omnis have a dispersion pattern that is closer to how sound emanates from live acoustic instruments and musical groups. If I perform a concert with my choir, together with a small string ensemble for example, I can typically walk around this ensemble in a circle, and I will feel that the sound is coming towards me from every point in the circle. It also doesn't matter whether I sit down or stand up, there is no big change in the sound that radiates towards me. The only speakers which are able to recreate this are omnis, and to a certain degree CBT style speakers.

4) And then of course, it's listening outside the sweet spot, or when there are more people in the room . Here omnis hold great advantages, together with CBTs again, multi channel systems, and hugely oversized horns that fill up the entire room with sound.

----------
Taken together, I think this goes a long way towards explaining why there are quite some listeners who perceive omnis as more "realistic" in the way they recreate music than conventional forward-firing speakers.

There is an exception to this: conventional forward-firing speakers will produce the "omni effect" if the sound being generated by them is of good enough quality - this is rarely done, hence few people even accept that it's possible. The further advantage of achieving this type of reproduction using conventional speakers is that it forces the playback system to be on its best behaviour to achieve the necessary quality - which means that you're hearing more of the recording, and less of the playback system.

 

[oivavoi]

There is an exception to this: conventional forward-firing speakers will produce the "omni effect" if the sound being generated by them is of good enough quality - this is rarely done, hence few people even accept that it's possible. The further advantage of achieving this type of reproduction using conventional speakers is that it forces the playback system to be on its best behaviour to achieve the necessary quality - which means that you're hearing more of the recording, and less of the playback system.

Interesting. Do you have any examples of such systems you can point to?

 

[fas42]

I've talked about doing this with my own systems over the years, but am rarely taken seriously. There are people on other forums, etc, who have done this, but again they rarely stir up any long term interest. Unfortunately, there appears to be no easily accessible, obvious example around - it really needs to organised into a show off, demo system, to illustrate what is possible, and its attendant advantages.

 

[Purité Audio]

You are confusing listening to live music and listening to its reproduction think bout how 'stereo' reproduction works.
Keith

 

[fas42]

Stereo reproduction is just one means of creating sound energy in an environment, say a room - live instruments are another means of doing that. If the sound cues in the room are good enough then our hearing interprets it in the same way as for live sound ... yes, it is very uncommon, but that's not the same as impossible. Understanding of audio needs to move along a bit, to allow this to be a little less uncommon ...

 

[Blumlein 88]

There is an exception to this: conventional forward-firing speakers will produce the "omni effect" if the sound being generated by them is of good enough quality - this is rarely done, hence few people even accept that it's possible. The further advantage of achieving this type of reproduction using conventional speakers is that it forces the playback system to be on its best behaviour to achieve the necessary quality - which means that you're hearing more of the recording, and less of the playback system.

 

[oivavoi]

You are confusing listening to live music and listening to its reproduction think bout how 'stereo' reproduction works.
Keith

Stereo originally means "hard, solid" - meaning that stereo sound is a means of creating a solid sound image.
https://en.wiktionary.org/wiki/stereo-

But of course, by now "stereo" has come to mean "two channel". And yes, I know how two channels create phantom images between them. I've always thought the two channel format to be inherently inferior, though. Three-channel or multi-channel makes much more sense to me. The problem is one of integration and interior design, and that almost all records are made in two-channel.

But there really isn't any way for me of getting to listen exactly to what the mixer or mastering engineer had in mind. The only way to do that would be to listen in his exact listening chair, with his exact speakers in his exact room, and furthermore we would have to magically swap heads and ear canals, since both our head form and our ear canals are important when it comes to how sound waves create phantom images for our inner eye. We would also have to make sure that the mastering engineer and me hear roughly the same frequency range.

You get the point. What I hear will never be exactly what the mastering engineer had in mind. The conclusion I draw is that I see the final mix as a starting point for my personal musical satisfaction. I don't want my system to introduce any big colorations to begin with. But if I want to change it with tone controls for example, so be it. If I also want to add room ambiance and increase the feeling of "being there" with the musicians by having speakers which create lots of reflections, it's also an obvious deviation from what the mastering engineer had in mind. But still - I can't see the problem with that?

 

[oivavoi]

I've talked about doing this with my own systems over the years, but am rarely taken seriously. There are people on other forums, etc, who have done this, but again they rarely stir up any long term interest. Unfortunately, there appears to be no easily accessible, obvious example around - it really needs to organised into a show off, demo system, to illustrate what is possible, and its attendant advantages.

I think your point would seem more credential if you actually could point to existing systems which could do what you describe, and which it was possible to listen to.

As for me, my understanding of how sound waves operate makes it difficult to believe that it functions as you describe it. The directional pattern of loudspeakers and/or musical instruments is more or less a given. It's just there. I can't see how a loudspeaker with limited directivity could sound like an omni, even in the case that the sound that comes out is super duper good. It's still going to be limited in directivity.

 

[Blumlein 88]

Existing systems have to be in a high state of tune to achieve this, and because most people don't understand how to, nor are willing to optimise to the degree necessary, they are as rare as the proverbial hen's teeth. Though, there are some extremely ambitious, and expensive systems in Asia that are this good - mentioned on the Whatsbestforum.

I will describe the experience in a somewhat different way: you mentioned listening to a choir in a post above; now imagine that choir in a room which has a long solid divider in the middle which runs from 1/4 of the way to 3/4 of the way across. So, the left hand 1/4 of the room is open, and the right hand 1/4 is open - and now you put the choir totally on the other side of the divider from yourself so you can see no-one - and then they start singing. You hear no direct sound, it's only what "peeps" around the ends of the divider that you hear ... finally, you go around, to talk to the choir - and discover they're not there: you've been tricked, a set of speakers was what was creating that sound, the whole time ...

Firstly that is not the same as you described previously. Secondly even in this situation the soundfield created by speakers and choir would be different. So there's a big leap to think you could get speakers to fool someone this way.

 

[oivavoi]

Firstly that is not the same as you described previously. Secondly even in this situation the soundfield created by speakers and choir would be different. So there's a big leap to think you could get speakers to fool someone this way.

Exactly.

But I actually think this is a distraction from the topic of the thread. I wanted to have a discussion on the merits or demerits of omnidirectional speakers, not discuss whether there exists super duper speakers somewhere which somehow manage to sound like omnis without actually being omnis.

 

[Cosmik]

Exactly.

But I actually think this is a distraction from the topic of the thread. I wanted to have a discussion on the merits or demerits of omnidirectional speakers, not discuss whether there exists super duper speakers somewhere which somehow manage to sound like omnis without actually being omnis.

Is there much fundamental mystery to it?

With both omni and directional you are going to get some direct sound, and some reverberant sound. For a given room, the number and timing of reflections would be different for each and would be related to speaker positioning relative to walls etc.

The ratio of direct to reverberant will be higher with the directional speaker. I would imagine that a directional speaker in a reverberant acoustic might sound a bit similar to an omni in a dryer acoustic - all else being equal. If the omni is truly omni, but the directional speaker has dodgy dispersion versus frequency (i.e. all else is not equal), then the omni scenario might sound better.

I would say it is not possible to state that either type is universally 'better', because it depends on the furnishings, shape and materials of the room. In a really dead room, an omni might give some relief from the acoustic deadness.

Presumably both types would sound identical in a truly anechoic chamber.

 

[oivavoi]

Is there much fundamental mystery to it?

With both omni and directional you are going to get some direct sound, and some reverberant sound. For a given room, the number and timing of reflections would be different for each and would be related to speaker positioning relative to walls etc.

The ratio of direct to reverberant will be higher with the directional speaker. I would imagine that a directional speaker in a reverberant acoustic might sound a bit similar to an omni in a dryer acoustic - all else being equal. If the omni is truly omni, but the directional speaker has dodgy dispersion versus frequency (i.e. all else is not equal), then the omni scenario might sound better.

I would say it is not possible to state that either type is universally 'better', because it depends on the furnishings, shape and materials of the room. In a really dead room, an omni might give some relief from the acoustic deadness.

Presumably both types would sound identical in a truly anechoic chamber.

Excellent comment!

 

[watchnerd]

If you want surround and immersion, HRTF is better.

 

[Phelonious Ponk]

I object the concept in principle. Not because it is wrong, but because none of the monitor speakers used in the recording and production process come close to resembling omni speakers.

As a result, you're more likely to hear something very different from the intended mix.

This. Though while I object in principle, I think omni-directional can be really pleasant in the right room.

Tim

 

[Purité Audio]

Stereo originally means "hard, solid" - meaning that stereo sound is a means of creating a solid sound image.
https://en.wiktionary.org/wiki/stereo-

But of course, by now "stereo" has come to mean "two channel". And yes, I know how two channels create phantom images between them. I've always thought the two channel format to be inherently inferior, though. Three-channel or multi-channel makes much more sense to me. The problem is one of integration and interior design, and that almost all records are made in two-channel.

But there really isn't any way for me of getting to listen exactly to what the mixer or mastering engineer had in mind. The only way to do that would be to listen in his exact listening chair, with his exact speakers in his exact room, and furthermore we would have to magically swap heads and ear canals, since both our head form and our ear canals are important when it comes to how sound waves create phantom images for our inner eye. We would also have to make sure that the mastering engineer and me hear roughly the same frequency range.

You get the point. What I hear will never be exactly what the mastering engineer had in mind. The conclusion I draw is that I see the final mix as a starting point for my personal musical satisfaction. I don't want my system to introduce any big colorations to begin with. But if I want to change it with tone controls for example, so be it. If I also want to add room ambiance and increase the feeling of "being there" with the musicians by having speakers which create lots of reflections, it's also an obvious deviation from what the mastering engineer had in mind. But still - I can't see the problem with that?

No the mastering engineer produced the file or record that is all we have , nothing else ,what he had for lunch on the day does not matter.
Keith

 

[Blumlein 88]

Friends at different times had the Mirage M-series speakers. Those were bipolar. Meaning not that they needed anti-depressents, but that they had the same driver complement front and back. They radiated the same sound front and back. Unlike with a panel speaker the front and back signals were in phase. They weren't quite omni-directional. In any case I listened many hours over those.

It is clear they excited room modes more than dipoles. Positioning was tricky and had to clear the rear wall and any corners by more than a regular box speaker. Think 5-7 feet here. Other than that I don't know they were as different as you might imagine. That was before I or my friends had good ways to do extensive room measurements. The main character was they were a bit dark with ample low end, but that was just the intrinsic balance of the speaker. These series of Mirage speakers were developed by Kevin Voecks using facilities at the NRC.

The balance was too different though we had Quads in the same location in the same room of the friend with the M3 si series. I wondered at the time about the backwave. In the dipole it is out of phase and gets reversed bouncing off the wall behind to become in phase with the front soundwave. In the bipole it would be in phase, and reverse phase onced reflected. Nothing could be determined in this sense however. Too many other differences.

Anyway, imaging might have been less pinpoint, and they need more space to the rear. They also had more of sense of space than monopole speakers. Thinking back I don't know they needed any big concessions either way vs regular monopole speakers.