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Old 5th May 2006, 09:25 PM   #1
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Default Sound reinforcement 'line arrays'

I was thinking for a while about building a incredibly loud set of speakers using pro-audio type drivers in a line array.

I've started out by ordering 16 of these: http://www.partsexpress.com/pe/showd...number=295-010

I'm going to start out with 8 per side and if that isnt enough I'll move on to 16 per side.

For lows I was thinking 2 of these per side:
http://www.partsexpress.com/pe/showd...number=295-085

I havent even really begun to consider different tweeters so suggestions are welcome.

What I'm going for in this project is sound quality comparable to higher end pro sound speakers(hopefully better) and of course high SplMax/efficiency.

Drivers should arrive next week, so enclosure building begins...
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Old 5th May 2006, 11:06 PM   #2
Andy G is offline Andy G  Australia
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Darn, I wish I could get something like those Dayton 5" over here ! I would have done the PA line array thing ages ago if I had access to driver like that !!!!

8 in series/parallel will give sensitivity of around 102dB at 4 ohm (quick brain calc) and around 400wrms power....... sweet

GO FOR IT !!!!
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Old 5th May 2006, 11:32 PM   #3
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Quote:
8 in series/parallel will give sensitivity of around 102dB at 4 ohm (quick brain calc) and around 400wrms power....... sweet
yeah I might not need 16 per side, but I'll probably end up doing that with 4 18" woofers per side and two big bullet horns, or compression drivers, or something
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Old 5th May 2006, 11:52 PM   #4
Andy G is offline Andy G  Australia
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What I would do is build 4 lots of eight, then you can use either one or two sections per side depending on venue. Don't forget, unless they are "in-situ" (go 16 a side for sure) then someone has to move them !!!

Remember, that 16drivers only gives you 3dB gain over 8 speakers.

10 a side in a 3/2/2/3/ taper would work nice and be a workable size I think !
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Old 6th May 2006, 12:24 AM   #5
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Quote:
Originally posted by Andy Graddon

Remember, that 16drivers only gives you 3dB gain over 8 speakers.
16 drivers would give him a 6db gain over 8 speakers. He'll gain 3db from doubling drivers and 3db from doubling their power handling.
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Old 6th May 2006, 12:43 AM   #6
Andy G is offline Andy G  Australia
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We have to be a bit careful here. That second lot of 3dB is due to impedance halving hence amp doubling current. Trouble is , the 8 driver system would already be running at 4 ohms, so on most PA amps you could not run 2 sets parallel.

In fact , it would probably be best to run the second set off a separate amplifier.
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Old 6th May 2006, 01:10 AM   #7
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Yes I was thinking two amplifiers would be the better way to do things.

I was thinking I'd seperate the arrays into cabinets of 4 mid/woofers. So evetually I might have 4 cabs per side.

Anyone have thoughts on a tweeter like this:
http://www.partsexpress.com/pe/showd...number=272-125
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Old 6th May 2006, 02:15 AM   #8
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Bass,

I strongly urge you to read Dr. Griffin's work that he has shared online. You say "sound reinforcement", but in what kind of venue(s). Of greater importance than number of drivers is the length of the array and XO points. The real advantage to line arrays is in their range of nearfield operation and the resulting dispersion pattern. In the nearfield they decrease in SPL by -3db per doubling of distance vs -6db for regular speakers. With listening distance of 25-50ft (avg for a small venue) you're talking about a 10db advantage which is huge. The nearfield range is line length and frequency dependent. The projection distance and frequency range will tell you the line length required and number of drivers you need (driver spacing). Plan it well and you'll get great results. Purchasing a bunch of midrange drivers is the easiest part.
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Old 6th May 2006, 02:44 AM   #9
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No particular venue... this is just for my personal enjoyment. It will probably go in the basement of my shed most of the time... I have little use for a system like this(except to **** off neighbors and impress friends), just money to blow and curiousity.

You're very right John. Crossover frequencys will be crucial here. I think Bi or tri amping wouldnt be a bad idea using a digital crossover like the behringer dcx.
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Old 6th May 2006, 05:16 AM   #10
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Hi John & Andy,

could you pls point me to Dr.Griffin's work ?

thanks,
roland
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