Any controlled directivity DIYs?

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http://www.diyaudio.com/forums/multi-way/231353-aino-gradient-collaborative-speaker-project-48.html
467038d1424448251-aino-gradient-collaborative-speaker-project-ainogneoc-v2-0-90-90-180-tile.png
 
Oh I see.

The SEAS DXT waveguide and opposing bass drivers in the Kii speaker are not really directivity controlling system. However the Kii 3 has quite nicely smooth but low directivity characteristics. The specific thing happens in upper bass at 60¤ (some phase cancellation?) KEF Blade and Devialet Phantom have similar construction. but with coaxial mid-tweeter.

DevialetPhantom2Web.jpg
 
Those speakers are not controlled directivity however.

Of course they are. In the upper bass to lower midrange the DSP creates a cardoid which controls directivity. In the midrange the baffle does it and in the highs the small waveguide.

However it could be a bit better.

kii three horizontal:
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Maximum SPL is not very high and the price is steep...
 

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Nate, whats your next step?

Working on getting a 90ish deg pattern down to 300hz or so from a 15 with other drivers to control the directivity. Getting there but not quite yet.

Nate - I was referring to the link to the small DSP speakers, not yours. Yours are very good.

Ahh. It would be interesting to see some polars of the Kii. I think it's funny how everyone is raving about how amazing they are for using that technology like no one has ever built a cardioid woofer before :rolleyes:
 
Ahh. It would be interesting to see some polars of the Kii. I think it's funny how everyone is raving about how amazing they are for using that technology like no one has ever built a cardioid woofer before :rolleyes:

Please take a look at one post above. :)

Directivity in the lows is comparable to much bigger speakers. This is what the concept achieved.
 
I think it's funny how everyone is raving about how amazing they are for using that technology like no one has ever built a cardioid woofer before :rolleyes:

I continue to be at a loss for the rational to have high DI down to very low frequencies. I just don't see it as important. And its not that I don't know how to do it, it was shown in my book some 13 years ago. I just don't see how it is important in a small room at LFs. A large venue, sure, but not a small room with early reflections well within the ears integration time (at LFs.) I don't understand how the ear would sort out a multitude of LF reflections within the time it takes to actually analyze a LF signal.
 
Then why did you start it? Judging my directivity control by normalizing the data is completely wrong and you know that. It is absurd that you keep bringing up this pointless and invalid comment.

So then "directivity controlled" means whatever the directivity turns out to be? That seems kind of meaningless to me.
 
Please take a look at one post above. :)

Directivity in the lows is comparable to much bigger speakers. This is what the concept achieved.

Ah ha! You posted while I was typing.

I continue to be at a loss for the rational to have high DI down to very low frequencies. I just don't see it as important. And its not that I don't know how to do it, it was shown in my book some 13 years ago. I just don't see how it is important in a small room at LFs. A large venue, sure, but not a small room with early reflections well within the ears integration time (at LFs.) I don't understand how the ear would sort out a multitude of LF reflections within the time it takes to actually analyze a LF signal.

Personally I'd like to keep a narrow pattern down to the room transition freq, and I suppose at 100-300hz different patterns might give a smoother result as measured at the lp in different rooms. I know when I compared my quasi-cardioid setup to a monopole in the 100-300hz region they did measure different but as I recall neither was an improvement. Something I'm going to look into more this winter. When you're talking about lf are you talking from, say, 20-100hz?
 
So then "directivity controlled" means whatever the directivity turns out to be?

It just means that the developer uses several techniques to "shape" the directivity as he wants it to be. When his goal was an increasing DI with frequency and he achieved that goal then his directivity is well-controlled.

Of course our goal is a constant directivity and I agree with you that we can apply this goal to all speakers on the market when judging them.
Directivity of the kii three is controlled, at least it seams that they tried to hold it constant. But they achieved a slightly increasing directivity index. This could be better. But its directivity is not a complete coincidence.

Just for comparison: here is a 12" + horn combination I build last year with a friend. Even in the low mids directivity index ist higher and overall more constant. It was a speaker we designed especially for in-wall usage in home theaters.

12" + 1" (on Limmer 022):
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Beside "constness" I find the value of DI to be very important. The kii three radiates wide in comparison to typical horn systems. This fact makes it more sensitive to rooms with high reverberation times. Personally I prefer a higher DI.
 

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