Loudspeaker Circular Arc Line Arrays

[jamikl]

Has anybody read or better still even built anything based on the information in Keele's paper on this subject. Paper is towards the bottem of the list on Keele's website. There are links to it already in this forum. In the trials 36 speakers with a dia. of 30mm were used. Would this still work with fewer but larger speakers. &5mm to 100mm.? the idea proposed seems to give very good covereage at all frequencies without having to build massively tall line arrays with huge numbers of speakers. Better WAF I would think and a lot of us need that.
jamikl

[bjorno]

Has anybody read or better still even built anything based on the information in Keele's paper on this subject.

Sometimes are array's very useful as point sources and I think that in normal living rooms midrange or very small woofers (max 4 inch like Aurasound NS3- or NS4-255-4D1) should work well in circular arc line array’s as long as the distance to the ceiling is not to close.

Yes, I tested fig 15 in Keele's paper no. 29 with 25 DaytonND20TB tweeters.

The dispersion smoothness was incredible for frequency’s up to about 10-15 kHz but as I'm just building a center speaker that has to be placed at the floor, I converted the tweeter array to a horizontal 25 element wave guided bessel array.

I have no picture of the circular arc line array but the Bessel array. See attached fig., where the outer mid bass drivers are filtered at abort 160 Hz and the remaining is Bessel configured.

This array will be used at a distance more than 5 m placed on a floor under a 2 x 3 m projector TV screen.

I also figured out for use as reference and to compare with, a short 27 cm point source trimmed 7-element bessel array with the tweeter with weight: 1:13:76:64: -76:13: -1 and also a circular array (20 x 20 cm).

Both array’s act as good point sources at distance over 2,5 m and at 5 m I had difficulty to hear the tonal color difference between the different tweeter array’s.

Other future planned DIY activities is to build and test the above short line array’s with 3 inch Aura NS3 instead and maybe later for the 7 element trimmed array, use Jordan JXR6, if I can afford to buy 14 of them.

Also later, I plan to test the circular array wave-guided in a ‘Unity horn’ with a big centred conical phase plug, and a 2 x 16-element circular arc line array, also using Aura NS3’s as I still have more than 50 left.

B

[bjorno]

more pics follow:

B

[bjorno]

Circle-array

[bjorno]

7 x Bessel array

[bjorno]

7 x Bessel

[bjorno]

Dayton ND20TB Z-plot

[bjorno]

One more picture:

7x Dayton ND20TB-4 Bessel array simulation.

[bjorno]

Absolute last picture: