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Author Topic: Narrow dispersion arrays  (Read 933 times)

Helge Dr. Bentsen

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Narrow dispersion arrays
« on: July 16, 2017, 04:45:38 pm »

I was looking at options for a long, narrow room and the list of line arrays with "narrow" horizontal dispersion (roughly 70 deg) is suprisingly short.

A quick search came up with four systems, K2, Flex array, KF737 and J8 (80deg).

Is there a reason for this?

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Ivan Beaver

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Re: Narrow dispersion arrays
« Reply #1 on: July 16, 2017, 07:31:10 pm »

I was looking at options for a long, narrow room and the list of line arrays with "narrow" horizontal dispersion (roughly 70 deg) is suprisingly short.

A quick search came up with four systems, K2, Flex array, KF737 and J8 (80deg).

Is there a reason for this?
I am not aware of any line array that has large horns, or anything more than the HF with much of any waveguide for pattern control.

Of course the narrower the pattern, the larger the horn has to be to maintain the same control to the same freq.

If you are trying to keep the pattern narrow, you really need to check out how low the "rated" pattern actual has control.  It may be MUCH higher than you would like.
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Mac Kerr

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Re: Narrow dispersion arrays
« Reply #2 on: July 16, 2017, 09:25:35 pm »

I am not aware of any line array that has large horns, or anything more than the HF with much of any waveguide for pattern control.

I would expect this is why line arrays typically have wide horizontal dispersion. In order to keep the horizontal coverage even the highs need to be what the mids are capable of.

Mac
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Tim Halligan

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Re: Narrow dispersion arrays
« Reply #3 on: July 16, 2017, 10:29:45 pm »

"When all you have is a hammer, every problem starts to look like a nail."

I don't play in the same league as you guys, but I'm convinced that many - if not most - of the venues I see with line arrays installed would be better suited to a well thought out "point source"/trap box system.

As ever, deployment is everything.

Cheers,
Tim
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Stephen Kirby

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Re: Narrow dispersion arrays
« Reply #4 on: July 17, 2017, 12:21:10 am »

Many "symmetrical" LAs actually turn off the mids from one woofer so that they don't narrow the midrange from interference.  If you are willing to manage pattern though destructive interference you might be able to rework some crossover points.  Which is what I suspect some of the DSP steering systems are doing.
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Keith Broughton

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Re: Narrow dispersion arrays
« Reply #5 on: July 17, 2017, 09:07:52 am »

I was looking at options for a long, narrow room and the list of line arrays with "narrow" horizontal dispersion (roughly 70 deg) is suprisingly short.

A quick search came up with four systems, K2, Flex array, KF737 and J8 (80deg).

Is there a reason for this?
Once again one has to ask "at what frequency is this dispersion measured at?"
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Helge Dr. Bentsen

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Re: Narrow dispersion arrays
« Reply #6 on: July 17, 2017, 04:42:15 pm »

Once again one has to ask "at what frequency is this dispersion measured at?"


A quick glimpse at the datasheets reveal that they all exibit this behavior from roughly 1K and up. Give or take an octave.

Entering the numbers into a simulation program one can clearly see the difference from 1K and up, so in theory it should help to reduce room reverberation in the top 3 - 4 octaves.
Shouldn't that be an advantage worth pursuing?
Or am I missing something?



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Mac Kerr

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Re: Narrow dispersion arrays
« Reply #7 on: July 17, 2017, 04:58:10 pm »


A quick glimpse at the datasheets reveal that they all exibit this behavior from roughly 1K and up. Give or take an octave.

Entering the numbers into a simulation program one can clearly see the difference from 1K and up, so in theory it should help to reduce room reverberation in the top 3 - 4 octaves.
Shouldn't that be an advantage worth pursuing?
Or am I missing something?

At the cost of uneven frequency response, or a big bump in low mid reverb relative to the rest of the system?

Apparently line array designers opt of smoother off axis response.

Mac
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Kent Clasen

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Re: Narrow dispersion arrays
« Reply #8 on: July 17, 2017, 05:03:46 pm »

I was looking at options for a long, narrow room and the list of line arrays with "narrow" horizontal dispersion (roughly 70 deg) is suprisingly short.

A quick search came up with four systems, K2, Flex array, KF737 and J8 (80deg).

Is there a reason for this?

Another 80* option is Nexo S12
https://nexo-sa.com/products/geo-s1210-st/
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Stelios Mac

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Re: Narrow dispersion arrays
« Reply #9 on: July 18, 2017, 04:12:02 am »

There's also:
d&b Q1 (75*, claiming down to 400)
d&b V8 (80*, claiming down to 250)
d&b Y8 (80*, claiming down to 500)
EAW KF760 (80*)
And I'm sure quite a few more.
The list for 90* boxes is much larger, but that's not quite you're looking for.

Like others have said however, I'd rather have smooth response off-axis - which is not easy to achieve in compact line array boxes. It's the same reason why you wouldn't treat a venue by using carpet to cover up all of the walls; you'd kill all HF and end up with a horrible boomy-sounding room. Obviously going with a narrow coverage box isn't going to be as dramatic, but constant directivity is quite a big deal.
Perhaps some point source boxes would be better suited for this application?
« Last Edit: July 19, 2017, 04:35:23 am by Stelios Mac »
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