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[Lee Buckalew]

To conform a sphere section the generated wavefront must not be an isophasic one.
Can't understand what you say is not correct....

We are not trying to conform a sphere section if the goal is to create an isophasic wave crossing each point on the listening plane rather than leaving an individual speaker or array of speakers.  In fact a spherical (or portion of a sphere) radiation pattern will not work to create an isophasic pattern that also can be configured to exhibit little SPL loss from front row to back.  +2 to -2 dB/SPL is easily achieved over 200+ meters.

Lee

[Alberto Escrina]

So you are talking about your system characteristics and not those of a point source array.
Now I see... Sorry about that.
You say efficiency will be a penalty with "standard" line array behavior but not with this different technology of directivity manipulation.
Standard line arrays , as you know, works with acoustic cancellation to achieve vertical directivity pattern.
In other words you buy, transport and fly loudspeakers for nulling some others in order to reach the desired directivity and playing just with interboxes angles.
Your specific system that, I suspect, comes from Buckinghamshire, UK or Whitinsville, USA (It doesn't matter really), doesn't work on that way?
Forget where for a moment. That's the steering program job and there's nothing to argue about that.
How the listening plane, the silent out-of-the boundaries zones and the front to back required SPL are achieved if not nulling acoustically some speakers with others working with phase and amplitude? Same procedure of a "standard" line array but incorporating, on this more elaborated system, additions and subtractions on the horizontal plane too? 

[Jean-Pierre Coetzee]

So you are talking about your system characteristics and not those of a point source array.
Now I see... Sorry about that.
You say efficiency will be a penalty with "standard" line array behavior but not with this different technology of directivity manipulation.
Standard line arrays , as you know, works with acoustic cancellation to achieve vertical directivity pattern.
In other words you buy, transport and fly loudspeakers for nulling some others in order to reach the desired directivity and playing just with interboxes angles.
Your specific system that, I suspect, comes from Buckinghamshire, UK or Whitinsville, USA (It doesn't matter really), doesn't work on that way?
Forget where for a moment. That's the steering program job and there's nothing to argue about that.
How the listening plane, the silent out-of-the boundaries zones and the front to back required SPL are achieved if not nulling acoustically some speakers with others working with phase and amplitude? Same procedure of a "standard" line array but incorporating, on this more elaborated system, additions and subtractions on the horizontal plane too?

I think you need to define what you are talking about, are your trying to say that something like the PRISM system mentioned way earlier in this thread sounds better then a modern Line Array should it be made up of modern point source boxes, if you do you are mistaken.

Honestly what Ivan is saying is that you should use 1 box per channel you want(that would be 1 with a mono system, 2 with a stereo system etc.) that has the characteristics that covers the area you want.

[Alberto Escrina]

I think you need to define what you are talking about, are your trying to say that something like the PRISM system mentioned way earlier in this thread sounds better then a modern Line Array should it be made up of modern point source boxes, if you do you are mistaken.

Honestly what Ivan is saying is that you should use 1 box per channel you want(that would be 1 with a mono system, 2 with a stereo system etc.) that has the characteristics that covers the area you want.

Hello Jean Pierre. Please note that the main subject of the thread is always mutating from issue to issue depending on what the posters understand or are interested on saying, so sometimes it gets confusing to follow.
If you want to see what I start to talk about please see my opening post on November 4th.
After Lee's interesting contributions we are not talking about Point Source arrays anymore and in no way I'm saying that a Prism system sounds better or worst than any other. In fact, I never heard one.
On my previous post I was asking Lee what other technique are steerable line arrays employing for creating hot spots on the desired audience area, the required SPL uniformity across it and the boundaries of the required area where, outside them, acoustic pressure should be the lowest possible.
The only way I'm aware of is the same one standard line arrays employ: sum and cancellation of acoustic energy. But i'm interested on hear Lee's information on this.
I'm not talking about how the technology manipulates phase and amplitude on both planes for establish the acoustic audience area. That's another issue.

[Lee Buckalew]

The only way I'm aware of is the same one standard line arrays employ: sum and cancellation of acoustic energy. But i'm interested on hear Lee's information on this.
I'm not talking about how the technology manipulates phase and amplitude on both planes for establish the acoustic audience area. That's another issue.

The issue of summation and cancelation of acoustic energy is not a line array issue it occurs in any arrayed driver or arrayed box system.  You keep mentioning point source arrays but they don't exist if you mean arrays made up of multiple point source boxes that still function as a single point source.  The closest that you can come to that that I have heard and used would be Danley where multiple drivers are all designed around a common horn device.  An array of many drivers creating a single coherent output on/in a common horn.


This discussion is all about how technology manipulates phase and amplitude from the problems inherent in standard multi-driver cabinets to arraying those cabinets to the approaches that a few current manufacturers are taking in a quest to eliminate those problems.  These are not separate problems inherent to line array vs. point source base designs they are issues of physical interaction of wavefronts between and among spaced devices. 

A Jericho horn, Genesis horn, etc. must combine multiple drivers for proper phase and amplitude summation and create a non-spherical wavefront in order to create a tapered SPL output.  This is utilizing technology to make desired changes to the individual drivers by combining their outputs in specific ways within the cabinet and within the horn.

Likewise Anya family, MLA family, Iconyx family, IC2, the newest processed systems from Clair, and many others have taken various approaches to creating non-spherical wavefronts and creating a specific new coverage from a grouping of speakers.  Some of the approaches beam steer to create required coverage angles (vertically)but do not articulate the array.  This approach requires many times the number of drivers and DSP channels to create the resolution that an array that does articulate can create. 
Some articulate the array and beam steer into either single or multiple beams in order to create specific vertical coverage angles.
Some articulate the array and calculate interactions of drivers required at the listener with no calculation of coverage angle. 

Each of these are different approaches (many are not at all similar in their approach except that they use processing) to attempt to get improved coherent summation of multiple drivers and through that to achieve a desired new coverage.  There are definitely pros and cons for the various approaches as has been mentioned by many.  There is scalability of the system, the ability or inability to change coverage rquirements either in SPL taper or area or both, weight, power, size, etc. each which may or may not be a requirement depending on a specific users needs.

I am still not clear on what you are attempting to ask.  There are no ideal systems for every situation but there are systems out there now that achieve far better results than have ever been available before.

Lee

[Alberto Escrina]

Hi Lee,
Thank you for your answers and your point of view.
Issues on this threat have been mutated everywhere, and there's not any special thing I will question right now.
It has been an interesting four day journey with inputs of all kinds.
Regarding my comment on reply# 54 about a system that is still unbeatable for me today, please take a look of my design (with Bruce Howze collaboration on midrange horns) with pictures from 1995, as well as a review on the legendary Live Sound! magazine:

8 - Fiberglass horn loaded - 2x18" RCF loudspeakers.
9 - 40H x 20V Fibergalss horn loaded - Community M4 Midrange compression Drivers
18- 40H x 20V Fibergalss horn loaded - Gauss HF4000 compression drivers.
Dispersion: 180 x 40
Total audio power: 8.000W
Estimated audience: 400.000

This system was rented for years as the "long throw" section of all kinds of outdoor massive shows.
Coherence, efficiency and output.
Cheers!

[Scott Holtzman]

Hi Lee,
Thank you for your answers and your point of view.
Issues on this threat have been mutated everywhere, and there's not any special thing I will question right now.
It has been an interesting four day journey with inputs of all kinds.
Regarding my comment on reply# 54 about a system that is still unbeatable for me today, please take a look of my design (with Bruce Howze collaboration on midrange horns) with pictures from 1995, as well as a review on the legendary Live Sound! magazine:

8 - Fiberglass horn loaded - 2x18" RCF loudspeakers.
9 - 40H x 20V Fibergalss horn loaded - Community M4 Midrange compression Drivers
18- 40H x 20V Fibergalss horn loaded - Gauss HF4000 compression drivers.
Dispersion: 180 x 40
Total audio power: 8.000W
Estimated audience: 400.000

This system was rented for years as the "long throw" section of all kinds of outdoor massive shows.
Coherence, efficiency and output.
Cheers!

Fascinating, do you have any measurements from the event?  What was the low frequency extension?  SPL at the back of the crowd?  Subjectively did it get above the fireworks at the extents?

[Ivan Beaver]

Fascinating, do you have any measurements from the event?  What was the low frequency extension?  SPL at the back of the crowd?  Subjectively did it get above the fireworks at the extents?

SPL and sound quality are not the same.  Sure, it has to be loud enough. but I have noticed an interesting thing at some shows.

I have attended/worked a number shows that normally would be considered "loud  This would include "gangsta rap", "thrash metal", "in your face rock" etc.

These were all single source systems in which a much large line array would normally be used.

In all cases, the system was not running at max potential, so that was not a limiting factor.

I was surprised at how "quiet" the shows were.  Typically around 103dBA slow.  That is a good bit lower than would normally be associated with those types of shows.

In all cases there was plenty of low end, so lots of energy.

My "guess" is that the FOH guys were able to get the "sound/feeling" they wanted, without the actual SPL.

Usually it is just "turn it up" trying to get clarity, until the system is out of gas.  Of course then your ears start to compress and it becomes self defeating.

If you can do that at a lower level, that is good for everybody.

I have other "theories" about hearing damage and ears ringing of a single source of sound vs multiple arrivals, but that is a different post.

[David Allred]

7 pages and counting on a topic nobody wants to discuss?  Funny.

[John Halliburton]

7 pages and counting on a topic nobody wants to discuss?  Funny.

And I'll pile on.

I keep getting the feeling the OP is missing the concept behind the Danley Synergy horn.  If we look at the photo of his big horn loaded system, the easy way is to take that low frequency horn, and take all the drivers out of the other sections, and load them in and around the inside of the flared sides, then use passive crossovers or active processing to time align the total broadband output.

As Alberto said, "Coherence, efficiency and output".  Except better.

Best regards,

John

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