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Author Topic: The high cost of deploying a true line-array  (Read 5231 times)

Robert Lunceford

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The high cost of deploying a true line-array
« on: August 03, 2014, 09:19:59 pm »

This is a spin-off from my previous topic "When is it a line-array?".
Tim McCulloch, Ivan Beaver, and Tom Danley all made the point that the length of the array was the critical factor in whether or not the speaker system performed as a line-array. Tim suggested that the length of the array should be at least 6 feet.
Let's take one of the sub-compact line array elements that was mentioned, the JBL Vertec 4886, and explore what the cost would be to deploy a system that would qualify as a true line array.
At a height of 7.8" for a single speaker, it would take (10) 4886 elements to make an array 6 feet in length. 20 elements for a L/R hang.
The only pricing I could find on the internet was for a little over $2900 for a single element.
$2900 X 20 = $58,000.
Now we have to figure out how many of the 4883 companion subs we would need to keep up with the arrays. We also have to add in the cost of the power amplifiers to power the system.

Other considerations to deploy the system include:
The cost of proper equipment to "fly" the arrays.
Cost to transport the system.
Time and labor to deploy the system.
Cost to insure the equipment and liability insurance.
How many amps will this system draw?

After all is factored in, I would estimate over $100,000 for a true sub-compact line-array.
There are a lot of small operations who would like to be riding on the line-array "band wagon" but it doesn't seem to be a practical system for smaller companies.

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Tim McCulloch

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Re: The high cost of deploying a true line-array
« Reply #1 on: August 03, 2014, 10:23:56 pm »

I've said before (not recently, however) that we purchase vertical arrays by the foot/metre.  The price per unit of measure is defined by long term output and a couple other considerations.

The costs associated with flying are the same, conventional trap box or vertical.  Once you're at the point of doing big theaters and/or small arenas, you need to fly the rig regardless of array type.

Big ol' edit ps. - Robert, you indirectly hit on the real issue that the system owner is facing:  how do I expand my business capabilities?  Most of the time that means being able to do bigger audiences, where you can leverage crew (a 4 man crew can do 3000 seats or 20,000 seats) and scale hardware.  Doing taller and/or deeper venues require a whole different way of thinking about PA deployment if all one has done is ground stacking.  Once a company has hit the limit of what they can do with stacks, the "next level" is a mighty expensive step just for infrastructure, and again that's regardless of horizontal/vertical/diagonal with spiral candy sprinkles... er array "geometry".  At some point the speakers need to go in the air, and that's expensive and not at all suitable to compromise.  Then you need new amp racks or new AC distribution (or both), or a complete re-think about AC and signal distribution if you're using powered speakers.

This is all about buying into a completely new system as part of a significant upgrade to the purchaser's capabilities.  It's just easy to forget what comes along for the ride with the shiny new PA and consoles - the ones you buy because now your PA is "better" than your mixers ;) - racks, AC power, utility trunks, labor to put it all together plus training and education.  These additional costs are seldom considered the first time an owner does a big upgrade; hopefully the lesson is not forgotten by round 2.

Short edit pps. - I discuss "the next level" here:  https://soundforums.net/entries/460-The-Next-Level-the-Unicorn-of-the-production-business  Note Jay Barracato's comment about +3dB$.
« Last Edit: August 03, 2014, 10:52:21 pm by Tim McCulloch »
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Lee Buckalew

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Re: The high cost of deploying a true line-array
« Reply #2 on: August 03, 2014, 10:29:45 pm »

This is a spin-off from my previous topic "When is it a line-array?".
Tim McCulloch, Ivan Beaver, and Tom Danley all made the point that the length of the array was the critical factor in whether or not the speaker system performed as a line-array.

That is not entirely the point they made.  It is the length of the array combined with the proximity of the acoustic centers of the drivers for each common band pass combined with the lowest frequency of interest.  The driver to driver distance is critical for proper acoustical summation in the band pass.  The length of the array overall is critical to LF control.  LF here is relative.  If you cross over your subs at 100Hz then an array of 11.5' should provide good LF control as long as the other criteria are met.  If you want control down lower then you need a longer array.

Lee
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Ivan Beaver

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Re: The high cost of deploying a true line-array
« Reply #3 on: August 04, 2014, 06:47:42 am »


Now we have to figure out how many of the 4883 companion subs we would need to keep up with the arrays.
In my opinion that is NOT the way to look at it.

I get asked all the time "How many subs does it take to keep up with XYZ tops?"

That is not the question.  The QUESTION should be "How many subs does it take to do the job in question?"

 The tops should be chosen FIRST for coverage needed and then output SPL needs.

Do you always run the tops at max output?  Yes some people do-others do not.

Also choice of music material/style makes a big difference on how many subs it takes.

How much louder do the subs need to be than the mains?  10dB-20dB or more?

Having subs capable of 30dB greater output than the mains is not uncommon. 

There is a HUGE difference in the cost of deployment between those different SPLs.

EDM takes many more subs than other styles of music.

And when you go outside-it takes at least twice (I prefer 4 times) the subs as indoors-to get the same "experience".

I know this is not the focus of the thread-but there is no "standard" as to the ratio of subs to tops.
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TJ (Tom) Cornish

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Re: The high cost of deploying a true line-array
« Reply #4 on: August 04, 2014, 07:32:28 am »

This is a spin-off from my previous topic "When is it a line-array?".
Tim McCulloch, Ivan Beaver, and Tom Danley all made the point that the length of the array was the critical factor in whether or not the speaker system performed as a line-array. Tim suggested that the length of the array should be at least 6 feet.
Let's take one of the sub-compact line array elements that was mentioned, the JBL Vertec 4886, and explore what the cost would be to deploy a system that would qualify as a true line array.
At a height of 7.8" for a single speaker, it would take (10) 4886 elements to make an array 6 feet in length. 20 elements for a L/R hang.
The only pricing I could find on the internet was for a little over $2900 for a single element.
$2900 X 20 = $58,000.
Now we have to figure out how many of the 4883 companion subs we would need to keep up with the arrays. We also have to add in the cost of the power amplifiers to power the system.

Other considerations to deploy the system include:
The cost of proper equipment to "fly" the arrays.
Cost to transport the system.
Time and labor to deploy the system.
Cost to insure the equipment and liability insurance.
How many amps will this system draw?

After all is factored in, I would estimate over $100,000 for a true sub-compact line-array.
There are a lot of small operations who would like to be riding on the line-array "band wagon" but it doesn't seem to be a practical system for smaller companies.
There is little doubt that line arrays are more expensive than some other systems.  Danley did a side by side with one of their large stadium horns - Genesis I think, vs a line array system and detailed the cost advantages of their system. 

However, I think you're latching a little too tightly to the idea of a "true line array" with X-number of boxes, etc.  The Meyer paper you linked to in your earlier thread pretty much debunks that idea entirely - there is no practical length of array where you get "true line array function" - meaning that the radiation pattern is cylindrical with respect to the audience plane.  There is no magic about 2 meters long, or any other number; only that as the array increases in length, pattern control extends lower - just like a "point source" system.  How low the pattern control needs to be held and to what extent (pattern control like everything else in audio is gradual - even a 3-box 4886 array has some control down to 300Hz - just not as much as it has at higher frequencies) is application dependent.

In the case of 4886/4883, the methodology is that pattern control is done via line length, and 4883 boxes are deployed in cardioid mode with the 300Hz crossover point, which provides low-frequency pattern control, if desired.

Every system has pros and cons, and applications where it is more suitable than others.  Vertical arrays are not the only solution, nor are they a magic bullet, however they can work pretty darn well in a lot of situations - even if they are not infinitely long.
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Ivan Beaver

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Re: The high cost of deploying a true line-array
« Reply #5 on: August 04, 2014, 08:24:42 am »

There is little doubt that line arrays are more expensive than some other systems.  Danley did a side by side with one of their large stadium horns - Genesis I think, vs a line array system and detailed the cost advantages of their system. 

.
We have all kinds of examples of fewer cabinets (and less cost) outperforming line array systems.

At this past Infocomm we had the owner of a company who has lots of "accepted on every rider" line arrays.

The year before last we covered a job in a large stadium for him (his gear was all rented out) and brought out 3 tops (2xJ1 and 1xJ3 and 4 TH812 subs).

This year he did the same event but brought out his own rig which was 36 tops and something like 18 or 24 subs-I don't remember

He is very proud of his system.  But he came up to me (and others) and told us the story that this year his system did not compare to the much smaller one we brought out.  He said at the far end (we had a single J1 pointed there) that his system was pretty much useless and just blowing around in the wind.  The true point sources don't do that.

He also said that we had much more low end.

He also said our system was much easier to deploy.

Just this past week I turned up a system for a 93,000 seat football stadium in which 5 cabinets covered around 90% of the seats.  The other 5 cabinets covered the area under the scoreboard and off to the extreme sides.

We were measuring 103-105dBA at the far seats 700'ish away.

BTW only 4 subs were used and were shaking seats at the far end-but that is a different story.

Currently line arrays have their place-are quick and easy to deploy (in most cases), but they are not the "end all" or the correct solution for many jobs.

I would argue that for most install jobs (and most portable jobs-outside of touring concert systems) a good point source is a much better solution. 

At least in terms of cost-physical size (ie blocking video screens)-sound quality-pattern control etc.
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David Sturzenbecher

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Re: The high cost of deploying a true line-array
« Reply #6 on: August 04, 2014, 01:50:53 pm »

Isn't a "true point source" just as mythical as a "true line array" ?
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Ian Mansfield

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Re: The high cost of deploying a true line-array
« Reply #7 on: August 04, 2014, 02:01:38 pm »


I would argue that for most install jobs (and most portable jobs-outside of touring concert systems) a good point source is a much better solution. 

At least in terms of cost-physical size (ie blocking video screens)-sound quality-pattern control etc.

Ivan, why do you say "outside of touring concert systems" ? Surely Jerichos could be easily deployed for this ?

 
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Tim McCulloch

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Re: The high cost of deploying a true line-array
« Reply #8 on: August 04, 2014, 02:28:12 pm »

Ivan, why do you say "outside of touring concert systems" ? Surely Jerichos could be easily deployed for this ?

I like Tom and the guys, and I'll say that just as not every venue requires (or even benefits from) a vertical array, building a true array of non-vertical speakers and getting uniform coverage isn't trivial.  And in keeping with Robert's topic here, an inherent part of such designing is getting the speakers located at whatever point(s) in space as may be required.  This is where the infrastructure expenses come in:  hoists & controllers, wire rope slings, round slings, shackles, and the smarts to inspect your stuff and destroy it (sings, chains, etc) when it fails inspection.

I'll again assert that the cost issues are more associated with playing at a new, higher level and less about the "geometry" of the speaker system.
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Ivan Beaver

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Re: The high cost of deploying a true line-array
« Reply #9 on: August 04, 2014, 03:01:28 pm »

Isn't a "true point source" just as mythical as a "true line array" ?
In theory a point source is infinitely small-produces all freq equally and radiates 360 at all freq.

Of course this is not what we want.  OK the first two items would be nice-but in most cases we do not want omni coverage.

So to have a particular pattern requires a horn.  To maintain that pattern down to a useable freq requires that horn to be large.  The narrower the pattern-the larger the horn has to be to work at the same freq.

All freq would be nice-but we are usually happy with most of the audio spectrum.

Small would be ideal-but that is not going to happen

Marketing says (and would like you to believe) that line arrays (line sources etc) produce a "can cut in half" type coverage.

But it you look at the data- you will see that is not at all what is happening.  There is a narrowing of freq to a very thin slice (varies with freq)-along with spurious lobes shooting out all over the place-up-down-behind etc that produce very erratic coverage.

Unless the line is very long-the on axis freq response will be very different from seat to seat-due to the varying rate of falloff with distance.

So yes-both are mythical.   But one is more "achievable" than the other.

However there are MANY (ie MOST) products that are "called" point sources-yet they are not.  They emit sound from different locations in space.  ie a woofer and a horn. 

The resultant pattern has lobes (like a line product) due to this spacing-around the crossover freq.  Products that have multiple locations of sound (woofer-mid-horn) have even worse lobing over a much wider freq range.

They may sound fine in one location-but as you move around in the pattern the sound changes.  This means different sound for different seats.  So which seat is right?

The one that pays the bills.  But does not every seat "pay the bills"?

Doesn't everybody deserve the same sound?
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