BG Neo8 multicell horn

[zmyrna]

Some forum members have shown us that BG Neo3 and Neo8 perform well when used with a custom horn or waveguide.

However a regular horn does not solve the radiation (beaming) problem of Neo8 on its long axis.

I am wondering whether a multicell horn taking advantage of the segmented structure of Neo8 would improve the radiation pattern.

 

[TBTL]

You can widen it but it will not necessarily be better, as you will get multiple frequency dependent lobes.

 

[zmyrna]

You can widen it but it will not necessarily be better, as you will get multiple frequency dependent lobes.

but because the radiating surface in each segment is quite small, wouldn't the lobing start at a higher frequency?

is lobing a well-known, well-documented phenomenon with multicell horns?

 

[bwaslo]

An externally hosted image should be here but it was not working when we last tested it.

 

[Pano]

I've spent a lot of time with multi-cell horns and never found the lobing to be a problem in practice. In fact I found them to have a more even polar response and wider sweet spot than most other types of horns. Not perfect, but still a very good approach. IIRC, Swan/HiVi used to have a pro PA box with their planar tweeters loaded by sectoral horns.

I'd say go for it.

 

[zmyrna]

Yes, that was my next question; what does that serrated polar response mean in practice (listening)? Which one is the lesser of a devil; lobing or beaming?

 

[Pano]

That may depend on you, and the room. I often read about all the horrible comb filtering and lobing from multi-cell horns, but I never hear it. I've asked others when listening to check if they hear it. So far, no one has. My Altec multi-cell were not perfect, they did beam some at the top, but not as badly as most horns of the same size. The fear of lobing could be more visual than auditory.

The problem you might have with the planar is that each cell will come of at a significantly different angle from the diaphragm. What effect that will have, I can't predict.

 

[hollowboy]

I am wondering whether a multicell horn taking advantage of the segmented structure of Neo8 would improve the radiation pattern.

Are you visualising splitting the horn only in the vertical axis? So for a 90*60 coverage, it would look a bit like three skinny 90*20 degree radial horns, piled on top of each other?

I'm intrigued.

User Patrick Bateman (and others) have presented some ideas that are less extreme - partially blocking some of the openings, and (much smaller) waveguides to smooth the exits of the openings. Some of this looked promising.

The fear of lobing could be more visual than auditory.

I've wondered about this. There are probably lots of ways the brain can fill in those narrow HF notches.

The problem you might have with the planar is that each cell will come of at a significantly different angle from the diaphragm. What effect that will have, I can't predict.

Valid.

But wouldn't only the angle between adjacent cells matter?

That is, if you had 3 cells (vertically), and your listening point was above the midline, I imagine that the output of the lower cell would be relevant only for what it does to the reverberant field.

 

[Patrick Bateman]

The easiest way to widen the directivity of the neo8 is to mask off the diaphragm with foam.

The foam will act as an acoustic low pass filter.

Have you seen my thread where I made phase plugs for the neo8?

Also, keep in mind that the neo8 can't play much past 10khz. The mass is just too high.

 

[zmyrna]

That may depend on you, and the room. I often read about all the horrible comb filtering and lobing from multi-cell horns, but I never hear it. I've asked others when listening to check if they hear it. So far, no one has. My Altec multi-cell were not perfect, they did beam some at the top, but not as badly as most horns of the same size. The fear of lobing could be more visual than auditory.

The problem you might have with the planar is that each cell will come of at a significantly different angle from the diaphragm. What effect that will have, I can't predict.

you are right, angle of the diaphragm would be the deal-breaker.

here are two more ideas:

one is to form a compression chamber

and the other is the extension of the foam wedge idea

actually, the compression chamber can also be made of acoustic foam

 

[zmyrna]

The easiest way to widen the directivity of the neo8 is to mask off the diaphragm with foam.

The foam will act as an acoustic low pass filter.

Have you seen my thread where I made phase plugs for the neo8?

Also, keep in mind that the neo8 can't play much past 10khz. The mass is just too high.

I always follow your posts/threads and youtube videos

Horn would bring down the HF extension even lower; I plan to use Neo3 from 6-8khz.