Line arrays with DR's and narrowing/pattern control. How much?

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Grant Bunter
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Line arrays with DR's and narrowing/pattern control. How much?

#1 Post by Grant Bunter » Thu Mar 26, 2020 3:28 am

We know from lots of previous references that the properties of line arrays dictate that:
The higher the stack, the more pattern control that is exhibited.

That requires some definition for me.
I've started with a pair of DR250's with melded arrays.
I assume that the melded array within itself, being from the top of the cab to the bottom, exhibits some pattern control.
How much?
Or, what is the vertical dispersion of a single DR250?
While we're at it, same cab, with a flat array, and a CD horn.

While we're at it, also, what is the vertical dispersion of a single melded Otop12, a flat array, and a CD horn (and does that change at all based on a choice of ASD or NSD/equivalent)?

Stage 2.
Add a cab each side
Lowermost cab is a melded array DR250
Upper cab is a CD horn DR250 (and if it's no different result wise, a flat array DR250)

What's the vertical dispersion now?

While we're at it, is that the same for all the Otop12 variants?

Is that measured from the top of the top cab and the bottom of the bottom cab?

TIA...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Bill Fitzmaurice
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Re: Line arrays with DR's and narrowing/pattern control. How much?

#2 Post by Bill Fitzmaurice » Thu Mar 26, 2020 6:57 am

The rule of thumb is that vertical dispersion is halved with each doubling of array height. Horizontal dispersion is unaffected.

Grant Bunter
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Re: Line arrays with DR's and narrowing/pattern control. How much?

#3 Post by Grant Bunter » Thu Mar 26, 2020 3:27 pm

Bill Fitzmaurice wrote:
Thu Mar 26, 2020 6:57 am
The rule of thumb is that vertical dispersion is halved with each doubling of array height. Horizontal dispersion is unaffected.
Thanks Bill.
So 1 to 2 cabs or 2 to 4.

What's the vertical dispersion of the DR's and Otops?
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Bill Fitzmaurice
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Re: Line arrays with DR's and narrowing/pattern control. How much?

#4 Post by Bill Fitzmaurice » Thu Mar 26, 2020 5:18 pm

It varies with frequency, from around 15 degrees at 15kHz to 360 degrees at 150Hz. But dispersion isn't everything, beam height matters almost as much. Even with 3 degree dispersion a six foot high beam will cover a lot of seats, and the J Array capability of the DRs and OTop JArray will handle anything.

Grant Bunter
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Re: Line arrays with DR's and narrowing/pattern control. How much?

#5 Post by Grant Bunter » Fri Mar 27, 2020 4:11 am

Bill Fitzmaurice wrote:
Thu Mar 26, 2020 5:18 pm
It varies with frequency, from around 15 degrees at 15kHz to 360 degrees at 150Hz. But dispersion isn't everything, beam height matters almost as much. Even with 3 degree dispersion a six foot high beam will cover a lot of seats, and the J Array capability of the DRs and OTop JArray will handle anything.
So, are you saying beam height is 6 feet?
Is that with a single cab?
What is the beam height of a 2 cab stack?
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

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Re: Line arrays with DR's and narrowing/pattern control. How much?

#6 Post by SethRocksYou » Fri Mar 27, 2020 4:47 am

I read it as a generalization, 6 foot high source (4 OTop12's is 5', 4 DR200's is 6' 8") at 3 degrees dispersion... One cab is 15 degrees, half of that with 2 cabs, half it again with 4 cabs would be 3.75 degrees

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Bill Fitzmaurice
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Re: Line arrays with DR's and narrowing/pattern control. How much?

#7 Post by Bill Fitzmaurice » Fri Mar 27, 2020 7:26 am

Grant Bunter wrote:
Fri Mar 27, 2020 4:11 am
What is the beam height of a 2 cab stack?
At minimum the height of the stack. That's at the source, spreading with distance.

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Re: Line arrays with DR's and narrowing/pattern control. How much?

#8 Post by Grant Bunter » Fri Mar 27, 2020 3:52 pm

Thanks!
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

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