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Author Topic: Midsized festival -> Line Array  (Read 12165 times)

Tim McCulloch

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Re: Midsized festival -> Line Array
« Reply #20 on: December 30, 2013, 07:44:58 pm »


That is the thing that most people wanting/pushing line arrays seem to "forget" or ignore.

My observation is that folks who screw up line array deployments also screwed up their 'point source' deployments.  Point sources are a bit more forgiving, but equally capable of sounding bad.  I'm not sure why we let flat pack, comb-filter builders off the hook and excoriate vertical nitwits.
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Re: Midsized festival -> Line Array
« Reply #21 on: December 30, 2013, 07:49:46 pm »

  I'm not sure why we let flat pack, comb-filter builders off the hook and excoriate vertical nitwits.

Names.  We need names...
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Peter Morris

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Re: Midsized festival -> Line Array
« Reply #22 on: December 30, 2013, 08:15:50 pm »

Yes,

I am familiar with the methods of measuring the sound.

We never had issious but in term of growing with the crowd and our local policy we are opting for line array.

Thx all for the reply's! If we find the correct sponsors to the finance the investmet we will be hanging line array. The other option will be suspending the current speakers in PA-towers.

Hi Tijs,

From the way your new legislation is drafted its not aimed at dealing with environmental issues but to limit short term exposures that the audience receives to something sensible.

A line array is more likely to be able to achieve consistent dBA levels across your audience area than most point sources, even a relatively short line array. I suspect those people offering line arrays have told you the same.

I think you have made the correct decision good luck organizing your festival.
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Peter Morris

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Re: Midsized festival -> Line Array
« Reply #23 on: December 30, 2013, 08:19:27 pm »

Do you understand what LAeq(60mins) is and how it is measured?  Your levels will constantly vary, a Leq is the calculated equivalent continuous noise level those varying levels represent over the defined period, in this case one hour.  The addition of the "A" to LAeq also defines that it is to be A-weighted levels used.  Say you had 30 minutes at 120dBA and 30 minutes at 80dBA, that would represent a LAeq(60mins) of 100dBA.   Of course you levels will likely vary much more in both level and period so this is not a simple measurement and not something your typical entry level meter can handle.  It also means that the sound levels at any point in time may not result in an exceedance at that time but could contribute to an exceedance anytime in the next hour.
Depending on the shape of the listener area, etc., a line array may help with directing more of the output at the listeners and less elsewhere, however it's probably not the approach you want if you want levels to drop off with distance.

Thats not how you add Leqs!
 
eg. if 100 dBA = 100% dose then 103 dBA = 200% dose.
 
Note -  Leq assumes an Exchange Rate of 3 dB and applies to all ISO and British Standard measurements. In some Countries, for example the USA OSHA Standards use a 5 dB exchange rate.
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Ivan Beaver

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Re: Midsized festival -> Line Array
« Reply #24 on: December 30, 2013, 09:06:06 pm »

My observation is that folks who screw up line array deployments also screwed up their 'point source' deployments.  Point sources are a bit more forgiving, but equally capable of sounding bad.  I'm not sure why we let flat pack, comb-filter builders off the hook and excoriate vertical nitwits.
I would not say that "flat front builders" are let off the hook.

I see people correcting them all the time.

Now what constitutes "flat front" may be up for debate.  Such as using 60 wide cabinets hard packed with the 15 angles flush.

"back in the day" there was a VERY POPULAR (and still used) trap cabinet that the "standard" usage was to always use an odd number of cabinets horizontally.  Then only use the ODD cabinets- (leave the even cabinets unplugged-or better yet shorted out).  The even cabinets were "spacers".

I built some arrays in EASE of both types of arrays (all on and even off).  The even off had much less interaction.
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Ivan Beaver
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Ivan Beaver

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Re: Midsized festival -> Line Array
« Reply #25 on: December 30, 2013, 09:14:05 pm »



A line array is more likely to be able to achieve consistent dBA levels across your audience area than most point sources, even a relatively short line array. I suspect those people offering line arrays have told you the same.


It depends on what you consider "short" and "even".

For example a 5' tall array (that is longer than many "short" arrays) will only exhibit the "line array" effect (3dB/doubling of distance) for about 5'.

If you go up to 1Khz it goes out to about 10' and down to 250Hz it is about 2.5'.

After that distance it will drop off at 6dB/doubling of distance-just like a "point source".

  So since most people are at least 10' away-they get the same losses.

It takes a lot longer array (ie more boxes) to get the "effect" people "think" they are getting.

But that doesn't stop them from "thinking" their system is doing something it is not.
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Peter Morris

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Re: Midsized festival -> Line Array
« Reply #26 on: December 30, 2013, 10:12:04 pm »

It depends on what you consider "short" and "even".

For example a 5' tall array (that is longer than many "short" arrays) will only exhibit the "line array" effect (3dB/doubling of distance) for about 5'.

If you go up to 1Khz it goes out to about 10' and down to 250Hz it is about 2.5'.

After that distance it will drop off at 6dB/doubling of distance-just like a "point source".

  So since most people are at least 10' away-they get the same losses.

It takes a lot longer array (ie more boxes) to get the "effect" people "think" they are getting.

But that doesn't stop them from "thinking" their system is doing something it is not.

Yes I know, but in this case the compromise we are talking about is meeting a legislative requirement which is measure in dBA. The low end is not really important to the measurement.

The other thing to note is people tend to use multiple point sources with overlapping patterns.  The point source performance of such a system will not come close to matching something like one of your Jericho horns despite have a similar number of drivers.

While I would love some Jericho horns they are not practical for a hire company like mine and many others.  From my experience I think the best you will do in this case is a medium sized line array. If the festival has the budget, a Martin MLC would be the go.
« Last Edit: December 30, 2013, 10:40:46 pm by Peter Morris »
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Bob Leonard

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Re: Midsized festival -> Line Array
« Reply #27 on: December 30, 2013, 11:46:48 pm »

The little white tent would appear to be 12' long and it also appears that is where FOH is located. Some quick scaling puts FOH about 40' from the stage and the back of the venue at about 100'. You're saying that a line array is needed for that distance? OK, so now that the array is in place what's being used to cover the giant gap up near the front of the stage? I've done public concerts using a pair of SRX725s per side for 1500 people in similar or even larger outdoor locations with better coverage up front, and can hit just under 100db at 75' without pushing them too hard at all. Strawberries to the hogs I say.
 
OP,
It appears your mind is made up at this point. Let us know how you make out with the array, and good luck with your concert.
« Last Edit: December 31, 2013, 07:45:23 am by Bob Leonard »
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Tim Weaver

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Re: Midsized festival -> Line Array
« Reply #28 on: December 31, 2013, 02:38:28 am »


I have an SRX rig. I'm interested in suggestions regarding a good method of tilting the 725 cabinets on scaffolding. I haven't seen many examples.


It's not that hard. Build a tilt board with the amount of tilt you need. Strap the board to the scaff, and strap the speakers to the board.
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Bob Leonard

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Re: Midsized festival -> Line Array
« Reply #29 on: December 31, 2013, 07:47:23 am »

I don't understand why fly points were not standard on the SRX cabs...

Fly points are an option at time of purchase.
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Re: Midsized festival -> Line Array
« Reply #29 on: December 31, 2013, 07:47:23 am »


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