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Author Topic: "Multi cellular array" vs "Single Source array"  (Read 22502 times)

Lee Buckalew

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Re: "Multi cellular array" vs "Single Source array"
« Reply #110 on: August 02, 2016, 11:34:15 am »

I read the patent which is quite informatieve and inspiring. However it only reveals one aspect of the "magic" behind MLA.

Basically it describes a generic optimization routine that iteratively minimizes variance in SPL, frequency response, leakage, rate of change in SPL over distance and rate of change in SPL over frequency with respect to predefined parameters.

With respect, but not limited, to MLA, FWAICT it's used in the first round of calculations in the Display software to determine the splay angles. You could think of it as Martin's proprietary "autosplay" function. But that's just one particular application of the routine.

I imagine that the same routine, again not limited to MLA, could be used to distill the MLA processing parameters, but that's not being mentioned in the patent.


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I have just been having the time to begin looking at this in greater depth. 
The descriptions actually do get into calculating the actual required position of each speaker unit or, conversely, utilizing a constraint of known speaker unit to speaker unit orientation, calculating required amplitude, delay, and phase corrections to electronically create a shift in speaker to speaker orientation always attempting to create an optimized frequency response and SPL contour based upon the user defined parametres.  This is discussed relative to both a 2D and 3D plot and to speaker elements constrained to a "Line Array" form-factor as well as other form-factors.

Lee
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Keith Broughton

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Re: "Multi cellular array" vs "Single Source array"
« Reply #111 on: August 02, 2016, 11:54:42 am »

utilizing a constraint of known speaker unit to speaker unit orientation, calculating required amplitude, delay, and phase corrections to electronically create a shift in speaker to speaker orientation always attempting to create an optimized frequency response and SPL contour based upon the user defined parametres. 
However, considering the mechanical pattern control of the drivers in the "cell" and the limited adjustment of the array configuration, "optimized" doesn't mean "correct".
I still don't see how this kind of system can offer even frequency response, coherent phase response and even SPL over the entire audience coverage area.
There must be compromises somewhere.
Not saying it doesn't sound good, just pushing back against the advertised claims.
Need more info.
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Lee Buckalew

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Re: "Multi cellular array" vs "Single Source array"
« Reply #112 on: August 02, 2016, 12:47:15 pm »

However, considering the mechanical pattern control of the drivers in the "cell" and the limited adjustment of the array configuration, "optimized" doesn't mean "correct".
I still don't see how this kind of system can offer even frequency response, coherent phase response and even SPL over the entire audience coverage area.
There must be compromises somewhere.
Not saying it doesn't sound good, just pushing back against the advertised claims.
Need more info.

As I am understanding it there is not only mechanical pattern control, there is also electronic pattern control since each HF and MF cell is made up of multiple drivers that interact vertically to create vertical pattern constraint.  These are further electronically controlled to change the pattern within the individual speaker cabinet and then from cabinet to cabinet.  Each cell and each group of cells is not built to create a flat wavefront but to create a  wavefront that propagates in a manner that will allow the control capability of the individual cells to interact properly. 

There is compromise in the weighting of SPL profile (Target), vs. the Non-Audience area profile (Leakage), vs. the Exclusion profile (Hard Avoid).  These compromises are user defined and are also affected by the number of cells available to provide control. The results, based upon the capability of the number of cells present and the user defined coverage requirements, are created in Display and show the actual ability or lack of ability to meet the desired target(s).

I can't say exactly what is being done (as in, I don't fully know) but I can tell you that the measurements hold up to the claims.  The claim being that the predicted outcome calculated in Display will be achieved within +/- 0.5dB SPL.

Lee
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Stephen Kirby

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Re: "Multi cellular array" vs "Single Source array"
« Reply #113 on: August 02, 2016, 01:32:23 pm »

Since there is no way to have multiple path lengths arrive at multiple audience positions coherently, there has to be some very sophisticated destructive interference (cancelation) going on to minimize the effect over as much of the audience area as possible along with the ability to provide higher levels of cancellation in "leakage" and "hard avoid" areas.  So you have a "virtual multi-cell" system rather than an actual multi-cell system of full bandwidth narrow pattern cells that can be adjusted for desired coverage.
Which brings up the question for folks like Lee who have experience with the system.  How does it match up in SPL for similar sized and powered systems that don't invoke as much cancellation?  Granted, even and controlled SPL is more desirable (IMHO) than ultimate SPL, but it would seem that energy is being expended in creating the coverage effect.
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Lee Buckalew

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Re: "Multi cellular array" vs "Single Source array"
« Reply #114 on: August 02, 2016, 01:54:54 pm »

Since there is no way to have multiple path lengths arrive at multiple audience positions coherently, there has to be some very sophisticated destructive interference (cancelation) going on to minimize the effect over as much of the audience area as possible along with the ability to provide higher levels of cancellation in "leakage" and "hard avoid" areas.  So you have a "virtual multi-cell" system rather than an actual multi-cell system of full bandwidth narrow pattern cells that can be adjusted for desired coverage.
Which brings up the question for folks like Lee who have experience with the system.  How does it match up in SPL for similar sized and powered systems that don't invoke as much cancellation?  Granted, even and controlled SPL is more desirable (IMHO) than ultimate SPL, but it would seem that energy is being expended in creating the coverage effect.

Overall SPL is certainly one of the variables.  Since creating the correct coverage across the defined audience plane does limit coverage in the leakage area and the hard avoid area the question remaining is, how much additional cancellation needs to be created and what resources are available, both physical and electronic.  Just as with any system, correct configuration for the wanted result is important.

There is no short answer for "how does it compare" for SPL capability, etc. as it depends on what the user is asking the system to accomplish. 

In actual use my experience is that the system can achieve very similar output to other similarly sized systems even when providing a significant amount of leakage and hard avoid control because the interactions created in the audience area are combining more effectively than in a line array configuration.  This is what is allowing such long distance coverage capabilities without delays. 


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Franz Francis

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Re: "Multi cellular array" vs "Single Source array"
« Reply #115 on: August 02, 2016, 02:00:51 pm »

Interesting thread. 

Since Lee has the most experience with the system my question, how does the mid-hi frequency behave under windy conditions in a properly deployed MLA rig?.

 

It's an indication of how good or better the alignment is with a multi box line array. Some designs are better behaved in a windy environments than others.

Franz
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Lee Buckalew

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Re: "Multi cellular array" vs "Single Source array"
« Reply #116 on: August 02, 2016, 02:08:21 pm »

Interesting thread.

Since Lee has the most experience with the system my question, how does the mid-hi frequency behave under windy conditions in a properly deployed MLA rig?.

 

It's an indication of how good or better the alignment is with a multi box line array. Some designs are better behaved in a windy environments than others.

Franz

Perhaps I have the most experience of those contributing here but there are many others with much more experience than me.

In windy conditions there is little to no phase shift/comb-filtering experienced.  Obviously this can be deployment dependent since outfills or front/lip fills may affect this. 

Lee
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Yoel Farkas

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Re: "Multi cellular array" vs "Single Source array"
« Reply #117 on: August 02, 2016, 02:33:55 pm »

Perhaps I have the most experience of those contributing here but there are many others with much more experience than me.

In windy conditions there is little to no phase shift/comb-filtering experienced.  Obviously this can be deployment dependent since outfills or front/lip fills may affect this. 

Lee
i (still) didn't figure out how it works. but as far i understand it has to take in account the temperature, as it change the speed of sound and the wavelengths. 
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Lee Buckalew

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Re: "Multi cellular array" vs "Single Source array"
« Reply #118 on: August 02, 2016, 02:44:03 pm »

i (still) didn't figure out how it works. but as far i understand it has to take in account the temperature, as it change the speed of sound and the wavelengths.

No, this is not varying with the temperature or wind to compensate, it is coherent enough that even though the wind does shift the sound (physics) as it shifts you are not hearing a bunch of different phase shifted sources hit you at different times.  All the wind does is rapidly move the coverage past you rather than have you rapidly move through the coverage.  If you are being presented with multiple path lengths that are not phase coherent you will hear it quite distinctly.

Lee
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