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Author Topic: When to use line array or not?  (Read 33516 times)

Tim Weaver

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Re: When to use line array or not?
« Reply #10 on: May 14, 2015, 07:46:38 pm »

You know what I mean. Tall and skinny is "in". It helps sell systems. I'm sure that had something to do with the SBH being created in the first place!
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Ivan Beaver

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Re: When to use line array or not?
« Reply #11 on: May 14, 2015, 08:22:19 pm »

You know what I mean. Tall and skinny is "in". It helps sell systems. I'm sure that had something to do with the SBH being created in the first place!
I will agree that the popularity of the skinny column had something to do with the SBH series.

Typically the rooms that need the advantage of the SBH are rooms that don't like the look of the other type of product that typically would be used-large horns.

Pattern control IS a big deal (in any room) and more important in reverberant spaces.

But we did not want to simply put out another "me to" product, but rather looked at what was really needed-then proceeded to come up with a better solution-no lobes-greater output-better quality sound etc.

It took several years of trying different approaches to pull it all together.  They were all based on the paraline technology, but the previous attempts were VERY different than the SBHs.
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David Sturzenbecher

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Re: When to use line array or not?
« Reply #12 on: May 14, 2015, 08:48:47 pm »

  Ie the balance of hi to low stays the same and doesn't change as you walk away.

Ok, I'll bite.

How can the balance of highs to lows stay the same on any speaker?  Every speaker has a different radiating pattern at every frequency.   Some speakers are better then others, Danley included...but I am having a hard time comprehending this statement.

Attached is a look at the SBH-10 at 100Hz at 8k.  How can the relationship between low and high stay consistent over distance?

Also, I didn't thinks horns were supposed to have spurious lobe like that. 

WARNING-Sarcastic answers follow:

9: When you want all sorts of "spurious lobes" shooting out all over the place-front and back

What is happening there?
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Keith Broughton

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Re: When to use line array or not?
« Reply #13 on: May 15, 2015, 07:50:10 am »

Most production companies I know use line array to fulfill riders and keep in business.

They would use mayonnaise jars if that was what was on the rider and they could charge for it.

You have to remember. These are sound COMPANIES. Not the "cool guy sound club". They need to make money in order to keep the doors open and right now traditional trap arrays aren't making money. Not because they don't work. Because they are not requested on riders.
And THAT my friends is the awful truth  :(
« Last Edit: May 16, 2015, 07:18:15 am by Keith Broughton »
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Ivan Beaver

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Re: When to use line array or not?
« Reply #14 on: May 15, 2015, 10:30:22 am »

An THAT my friends is the awful truth  :(
The sad reality is that sound quality is not even in the top THREE reasons people purchase large scale loudspeakers. :(
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Tom Danley

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Re: When to use line array or not?
« Reply #15 on: May 15, 2015, 11:12:24 am »

Ok, I'll bite.

How can the balance of highs to lows stay the same on any speaker?  Every speaker has a different radiating pattern at every frequency.   Some speakers are better then others, Danley included...but I am having a hard time comprehending this statement.

Attached is a look at the SBH-10 at 100Hz at 8k.  How can the relationship between low and high stay consistent over distance?

Also, I didn't thinks horns were supposed to have spurious lobe like that. 
What is happening there?

Hi David
There is no truly constant directivity speaker other than a very tiny point source BUT compared to arrays of individual sources that hang in a line,  a single full range horn can project much less sound to the rear, sides, up and down than a larger array and can do so more constantly, over a broader range of frequencies.     
In addition, because it has the advantage of horn loading and coherent summation of the individual drivers, it generally requires far less of everything including $ for a given spl / distance.   
 
The SBH 10 is the most extreme pattern speaker we make, built for use where a very narrow vertical pattern is needed like in Churches etc but is still limited by its horn mouth size and geometry.   
Compared to the steerable arrays it replaces, it too radiates less energy out of pattern than much larger speakers which also tend to cost 6 to 10 dB or more$.   

If youre a Synaudcon member, Pat has some measured results and recordings made in a very reverberant space using a prototype SBH-10 and a number of much larger much more costly arrays as how it compares to the other approach is what matters.     

You ask what is happening there?     Well lets see, you have what 40 or 50 dB of loudness range shown in a model based on actual measurements, if you used a larger loudness span it might look worse but how mcuh do lobes -20 or more down make?  To get an idea what it really means in use, why not show what a similar sized array measures in the same loudness span / range and see for yourself what it shows.     Do post real measurements if you have them if you want to see what's different.
 
The issue is the self interference or interference pattern that multiple but uncoupled sources radiate, in an array where the sources are more than about 1/3 to wavelength apart, they radiate independently, do not have mutual coupling.   

The acoustic levitation sources and systems and sources I used to develop for NASA were also interference based devices fwiw, so i am somewhat familiar with how sound radiates and what an interference pattern is.
 
The arrays legendary reduced SPL fall off vs distance only happens because of the interference pattern and is so frequency dependant due to the source spacing being a governing factor that they curve the arrays (physically or electronically) to make it more like a point source (an astigmatic point source).

The Huygens wavefront summation on axis is the selling point for the arrays and the part shown in the models but ignores what happens off axis AND what happens with time.    If one always has sine waves then its simple BUT some music and speech is time variant and not continuous sine waves.    If one fed an array with a single short impulsive sound or say speech then the array shows an additional weakness as what arrives at ones ears or STIpa measurement microphone is scattered in time, dispersive in time as they say because there is a separate path length and arrival delay between each source and the listeners ear or measurement microphone.     

An ETC shows the arrivals begin with the closest source and end with the farthest source regardless of the time duration of the actual input signal and this changes at every distance. 
 
In Europe where sound systems often also must work as emergency warning systems, it turns out that the arrays measure very poorly using STIpa / have poor intelligibility compared to sources like the Synergy horn which radiate from a single point in time and space.   Thankfully for the arrays here, understanding words in emergency announcements or songs is not required legally or considered that important yet.

The plot I included is the measured beam width plot for one of the smaller Synergy horns, it illustrates a near constant directivity, the result of a more constant directivity also means that compared to arrays, the sound timber does not change appreciably with distance, the system does not fall apart sonically at 100 feet or 200 feet and require delay rings.     
Some of the stadiums using these kinds of single point radiation sources have the listeners 800 feet from the speakers and except for some hf absorption, still sound HiFi when you play good program material.     Not producing the arrays interference pattern also means it sounds the same as you walk side to side within the pattern and if the wind blows, you dont hear the effect of the interference pattern like the arrays produce.    Constant directivity also means that one also often avoid down fills as when you move off axis (like below the system) the spectral balance also does not change only the SPL falls.

Both of our companies each have a commitment to our approaches, yours with the interference based array and ours with a full range horns with a single point of radiation but if interested, I did cover more of the acoustic engineering in the chapter on loudspeakers I was asked to write in the latest edition of the Audio Engineers Handbook .     

We are not an advertising driven company and we have never given stuff away to get it on tours etc and it would have been much much easier marketing and engineering wise had we gone with the industry flow and used the array approach given the cumulative effect of marketing of them. 
   
Instead we went with something that makes much more sense to me acoustically / scientifically / audibly, to make the best sound quality and most sound per box, radiating from a single point, with the greatest over all directivity possible even if the box count per job and cost is clearly smaller.   
Right now we are bidding on supplying 16 boxes for a stadium where a consultant has specd 128 of the big array boxes, the same box that is miserable in the old facility for the same job which predicts less even coverage and much more stray sound and higher cost.
 
While that latter point makes our approach less attractive to some installers and designers, many stadium jobs  have come from side by side comparisons where these same arrays have been installed and tweaked by the mfr / installers with unsatisfactory results so the end user makes the decision which way to go based on sound alone, not on how much can be sold.
 
The N and D in the old Hopkins Stryker equation is part of the why, its acoustical physics of it plain and simple

Best,
Tom Danley
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David Sturzenbecher

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Re: When to use line array or not?
« Reply #16 on: May 15, 2015, 12:14:29 pm »

Hi David

Best,
Tom Danley

Thank you for your response Ivan.  I appreciate your insight.  But what I got out of all that, is that the initial statement went from "the balance of highs and lows stay the same as you walk away" to "compared to arrays horns can project less sound to the rear".   My question was directly related to how I was told in a previous post on horns behave.  It seems the response hardly touched on that, and instead focused on the shortfalls of linear arrays.   It would be nice if you could clarify your response, without bashing other technology. 


Both of our companies each have a commitment to our approaches, yours with the interference based array and ours with a full range horns with a single point of radiation



I am not sure what you mean by this comment.  I am a system designer and system tech.  I design systems with products from a variety of manufactures, including a company that you work for.  I feel each company has product offerings that make them a proper choice for each one of my customers, be it price, performance, aesthetics, or any number of other variables. I am not committed to any one design philosophy, and that should be evident as my fellow designers and I have personally paid to travel to numerous Danley "flagship installations" (and even designed and installed a few).   I have a very hard time designing speakers into a project in which I have not actually listened to...no matter how great they look on the computer screen.   

At the end of the day, I simply asked for clarification to a statement that seemed impossible for any speaker to achieve and in return I got a response focused on the downfalls of line arrays.   If you are going to try to sell your product to me, tell me why your stuff rocks, not why the other guys stuff sucks.
« Last Edit: May 15, 2015, 12:22:14 pm by David Sturzenbecher »
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Ivan Beaver

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Re: When to use line array or not?
« Reply #17 on: May 15, 2015, 01:34:47 pm »

Thank you for your response Ivan.  I appreciate your insight.  But what I got out of all that, is that the initial statement went from "the balance of highs and lows stay the same as you walk away" to "compared to arrays horns can project less sound to the rear".   My question was directly related to how I was told in a previous post on horns behave.  It seems the response hardly touched on that, and instead focused on the shortfalls of linear arrays.   It would be nice if you could clarify your response, without bashing other technology. 
 


It is a known fact (and VERY easy to hear for yourself-just do it) that horns have far greater rejection to the rear than cabinets that are simply front loaded.

This allows for greater gain before feedback-less energy going to places you don't want it to and so forth.

Of course how much-depends on the physical size and the radiation pattern of the horn.  They are NOT all created equal.

A small horn is NOT going to do that-it has to be large to have any sort of real pattern control.

As most people KNOW (or at least SHOULD know) the "magic of a line array is that it falls off at a slower rate than a "point source".

What most miss is that this rate of "falloff" is DIRECTLY tied to the LENGTH of the array-NOT the number of boxes and the FREQ that you are talking about.

As you go lower and lower the array has to get larger and larger to maintain this same rate of "falloff/decay".

Of course this "fall off" is due to the cancellations that go on within the array and loiwer the level close to the array by creating chaos in the soundfield-but that is a different argument.

So it should be obvious that if 10K is falling off at one rate and 1Khz is at a different rate and 200Hz is at a still different rate, then there is no way it could possibly have the same response at all seats.

Predictions are one thing-measurements of REAL situations are often quite another.

ANY prediction makes a bunch of "assumptions" and then gives an answer-right or wrong.

An accurate measurement (assuming done correctly) does not have these "assumptions, and gives a much better idea of what is REALLY going on.

I guess that is the reason for the current popular trend to not show any measurements and just rely on "printed numbers" but I won't go there-at least not now anyway.

Below is ACTUAL measurements-done outside on a LARGE empty parking lot  (close to 1000' of empty space before you hit some trees).

It is a single SBH10 on the ground-with the mic mid way (so 2.5' off the ground).

The measurements start at 1M and then double till we get to 10M and then it is every 10M after that-out to 100M.  So the distances are not doubling-hence some of the lack of "continuity" to the falloff.

While no loudspeaker is perfect, you will see very similar response (although the actual SPL is dropping off) at the different positions-until you get to 50M.

At that point the HF starts to drop off more rapidly.  This is due to the measurement conditions-a warm day-in the middle of the afternoon-on black asphalt.  The HF is starting to be "directed up" due to the heat from the asphalt.  And with a narrow horn, it does not take a lot to change it.

Had this been done in a LARGE inside area-the HF rolloff would not be as drastic.

I can tell you for a fact, that at 300' or more the HF is still nice and strong and clear and detailed-when mother nature does not get in the way.

So you could argue that the measurement was not "done correctly"-I can accept that.  But we do not have access to a large enough indoor space to do it properly, and we had some time that day, without the luxury of waiting for a cooler day that was overcast etc.  We had a chance to gather some data-so we did the best we could-conditions permitting.

But we are showing the data ANYWAY.

I have done measurements of the "other technology" and know why users of this don't show anything like this.  There IS a reason.

I would love to see the same type of measurement done with a "interference array" (since you don't want me to talk about other technologies).

I would love to see some MEASURED proof about the even coverage.  My ears and measurements tell me different. 

I will take MEASURED data ANY DAY over predictions.
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Ivan Beaver
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David Sturzenbecher

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Re: When to use line array or not?
« Reply #18 on: May 15, 2015, 02:36:12 pm »


I would love to see the same type of measurement done with a "interference array" (since you don't want me to talk about other technologies).


Well, you only made it 6 sentences in before that didn't mater anymore   ;)

My initial question really has nothing to do with line arrays at all, so I am not sure why the responses to that question keep referencing them.  Your measurements also show that between 10M and 20M the attenuation (of this particular speaker, at this particular time, at this particular location, etc, etc) is anything but consistent with a 6dB drop per doubling at say 2.5kHz. Which was the point I requested clarification of, no?  "the balance of hi to low stays the same and doesn't change as you walk away."  I am sure the results would have been better with a flown system, and a ground plane measurement, as this particular speaker was designed to be used.   

I am willing to accept that "that balance of highs and lows stay the same as you walk away, when the speaker is properly deployed, within the design parameters of the speaker."  But this could also said for other "technologies".  Damn...There I went and did it.

I do indeed appreciate your guys explanation, exploration, and passion on this topic.  Please don't take my further questions and slight return sarcasm the wrong way.
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TJ (Tom) Cornish

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Re: When to use line array or not?
« Reply #19 on: May 15, 2015, 02:38:51 pm »

So it should be obvious that if 10K is falling off at one rate and 1Khz is at a different rate and 200Hz is at a still different rate, then there is no way it could possibly have the same response at all seats.
To be clear here, horns have pattern control limitations as well - even Danley horns.  :)  While the horn may allow you to control the pattern from 500Hz up (or whatever depending on the box in question), there's going to be the same amount of LF off the back of a Danley box as any other box (or line array) of comparable size.

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Re: When to use line array or not?
« Reply #19 on: May 15, 2015, 02:38:51 pm »


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