Definition of an omni please

[Theta]

Lots of speaker have a driver on top, does that make them Omnies. Some open baffle speakers have just a tweeter in back, are they Omnis?

 

[Blumlein 88]

Omni's should radiate equally in all directions. Some are close, some aren't. MBL probably has the best true omnidirectional speaker.

I don't know if any speakers other than the MBL's are true omnis.

There used to be some Ohm Walsh speakers that were. Don't know if they are still made. German Physiks speakers use the same bending wave principal.

Bi-directional speakers with the same drivers front and back can come close. Mirage made some of those, and some still do like Axiom audio.

 

[Flaesh]

Some open baffle speakers have just a tweeter in back, are they Omnis?

Nope. Rear tweeters in dipole loudspeakers are inverted.

 

[Blumlein 88]

In case you aren't sure, a dipole is like a Magnepan speaker or other panels speakers. Sound emanates from the front and back. The sound in the rear is 180 degrees out of phase with that in the front. You can also have the same effect with normal cones in open baffle designs. As mentioned in those a rear tweeter is inverted in phase or 180 degrees out of phase with the front.

A bipole is like a pair of speakers back to back in phase. If properly made it can come close to being an omni. The speakers on both sides are in phase.

 

[Deleted member 21219]

There was only one speaker that attempted to be a true omni; the dodecahedron design. The one I remember was from Design Acoustics.

Jim

 

[Timcognito]

Larsen uses the walls to radiate sound from walls and ceiling and needs to be against the wall.

Ortho Acoustic – Larsen HiFi

www.larsenhifi.com

 

[Bjorn]

Larsen uses the walls to radiate sound from walls and ceiling and needs to be against the wall.

Ortho Acoustic – Larsen HiFi

www.larsenhifi.com

They are not omni. They don't radiate backwards and also avoid the nearest side wall reflection. They have increased reflections from the ceiling because the drivers faces upwards.

 

[Blumlein 88]

There was only one speaker that attempted to be a true omni; the dodecahedron design. The one I remember was from Design Acoustics.

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Jim

I wonder how effective they were at being an omni. Soundfield type microphones can be any pattern including an omni with the diaprhagms in a tetrahedral pattern. I would think speakers could do this in reverse. However, microphones can be quite small versus the wavelength while any speaker with say four 3/4 inch drivers would be unable to put useful bass. There would be ways to work around that with multi-drivers, but the integration becomes rather complicated.

 

[Vincent Kars]

https://www.duevel.com/en-gb claims to make omni directional speakers.
I believe the acoustic lens by B&O is more or less the same principle.

 

[Blumlein 88]

https://www.duevel.com/en-gb claims to make omni directional speakers.
I believe the acoustic lens by B&O is more or less the same principle.

I've seen those, and would like to see someone do some measurements of its dispersion.

 

[Timcognito]

They are not omni.

The majority of sound doesn't come directly. You can define them anyway you prefer.