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Circular array question

RyanPoolrp

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So I know Tekton has so lobbing issues with it's array but I'm curious if you were able to get the tweeters close enough together, could you get rid of that issue.

Going further, I'm imagining a extremely tight 6 tweeter array (pentagon with one in the center) and then surrounding that with a circle of say 3-inch mid range drivers to create a virtual coaxial driver but using an array instead of just 2 drivers.

My question, is it possible that this design could work? Would it be possible to get both the advantages of an array and coaxial design? Also just any comments from the smart people on this site regarding this idea.
 

fluid

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So I know Tekton has so lobbing issues with it's array but I'm curious if you were able to get the tweeters close enough together, could you get rid of that issue.

Going further, I'm imagining a extremely tight 6 tweeter array (pentagon with one in the center) and then surrounding that with a circle of say 3-inch mid range drivers to create a virtual coaxial driver but using an array instead of just 2 drivers.

My question, is it possible that this design could work? Would it be possible to get both the advantages of an array and coaxial design? Also just any comments from the smart people on this site regarding this idea.
The Tekton array is fairly well done, it uses frequency shading to bring the outer drivers in progressively lower so the high treble is only from the centre tweeter.

In reality the physics creates a trade off that makes it difficult. To make the distance smaller the devices have to be smaller and then struggle to go lower infrequency due to reduced surface area and displacement. Going lower in frequency is needed to avoid the lobing so you end up chasing your tail.

Good thread here to understand the Tekton more

https://www.diyaudio.com/forums/mul...rstanding-tekton-tweeter-array-schematic.html

To keep the directivity even the arrayed drivers need to be in a ring or have the same vertical and horizontal distances otherwise the directivity will be narrowed or widened in that direction based on the distance between them.

Nils Ollerer has done a lot of simulation and experimentation into different array configurations, it is in German but at the bottom of the page there is an English translation, two pages open at the same time makes it easier

https://docplayer.org/125578399-Quasikoax-prototyp-inhalt.html
 
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RyanPoolrp

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The Tekton array is fairly well done, it uses frequency shading to bring the outer drivers in progressively lower so the high treble is only from the centre tweeter.

In reality the physics creates a trade off that makes it difficult. To make the distance smaller the devices have to be smaller and then struggle to go lower infrequency due to reduced surface area and displacement. Going lower in frequency is needed to avoid the lobing so you end up chasing your tail.

Good thread here to understand the Tekton more

https://www.diyaudio.com/forums/mul...rstanding-tekton-tweeter-array-schematic.html

To keep the directivity even the arrayed drivers need to be in a ring or have the same vertical and horizontal distances otherwise the directivity will be narrowed or widened in that direction based on the distance between them.

Nils Ollerer has done a lot of simulation and experimentation into different array configurations, it is in German but at the bottom of the page there is an English translation, two pages open at the same time makes it easier

https://docplayer.org/125578399-Quasikoax-prototyp-inhalt.html

I know only the true tweeter in Tekton is the center, but what if it wasn't. And what if the drivers themselves were manufactured such they were the center to center distance was as close as possible (maybe 1.1 inches for 1 inch tweeters in any given direction). The c-to-c distance for the mid range would be about 6.5 inches in the longest direction.

Shouldn't the tweeters be able to play lower as you would be using 6 of them which means the mid ranges can be crossed lower which hopefully would be low enough to allow their center to center distance to be ok.

I don't know the math though and so I'm wondering if the above would work.
 

fluid

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The central driver in a concentric array is almost always used alone for the highest frequencies to avoid interference from the surrounding drivers. For the drivers to combine into a single source they need to be placed within a 1/4 wavelength of the frequency being produced.

In your example of 1"tweeters with no excess face plate or magnet the CTC distance between the outer elements would be 2". These would combine up to ~ 1700Hz and create interference patterns above this frequency.

By frequency shading the outer drivers it allows them to offer support at the lower frequencies where the extra radiating area helps but stops them creating so much destructive interference.

There is an inherent compromise between lobing, distance and crossover frequency. It is practically impossible to make the drivers small enough and go low enough to avoid any lobing, but that doesn't mean that you can't make a good sounding speaker using this idea.
 
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