How to build a 4-element inline gradient subwoofer array

This is my attempt to recreate one of the arrays described in an AES paper called Subwoofer positioning, orientation and calibration for large-scale sound reinforcement.
Previous video (The BEST subwoofer array for large concerts?): • The BEST subwoofer arr...
Gradient sub array explained: • Why do you polarity in...
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I love to geek out about the physics of sound. This channel focuses on the growing opportunity for live sound engineers to improve their confidence and consistency through the understanding of the principles of sound system design and optimization. My goal is to make this channel upfront and honest about my success and failure, so you can learn from both.
I am always open to suggestions and feedback so please comment on this video or contact me through my site.

[@stevecochran77]

Rad! This is exactly what I did in Hilton California C&D at NAMM last year!

[@ayobamijioni6932]

Thanks! Can you please do a video of what you would do in covering a 360 degree audience seating around a centered stage

[@nathanlively]

Sure! I can think of a couple places where this has been covered:
Michael Krieg - Line Array Fundamentals
school.sounddesignlive.com/courses/live-sound-summit-2018/lessons/session-1-michael-krieg-line-array-fundamentals
Bob McCarthy - Metallica
school.sounddesignlive.com/courses/live-sound-summit-2018/lessons/session-9-bob-mccarthy-metallica

[@Cascadesplitboarder]

Would be interested to see how a standard cardioid end fire center cluster would look combined with this

[@nathanlively]

Hey John, thanks for the suggestion, but I'm not sure I know what you mean. What is an end-fire cluster? Can you show me an image?

[@Cascadesplitboarder]

@@nathanlively a center cluster of subs in a cardioid configuration to fill in the coverage gaps in the center-front of the audience area. Something like 1 or 2 of these 3-box stacks. upload.wikimedia.org/wikipedia/commons/thumb/5/5b/Caissons_grave_DSC_5563EC.jpg/600px-Caissons_grave_DSC_5563EC.jpg

[@wesleysstark]

I’ve been having the same issues with layers changing within Mapp

[@nathanlively]

Ok, good, it's not just me. I've noticed that selecting layers in the new MAPP 3D is also a bit of a struggle. Hopefully they'll get that worked out.

[@chrisdileo]

I’d also be curious to see what an end fire center cluster would look like with this. Especially as this seems to be directing a lot of the energy at a 45° angle from the stage.

[@nathanlively]

Thanks for checking out the video Chris!
> an end fire center cluster
Hmmm, you would need a lot of real estate for an end-fire array in the center in front of the stage. Maybe you were thinking of a 2-element end-fire?
> this seems to be directing a lot of the energy at a 45° angle
You understand that that is goal, though, right? It's on purpose.

[@chrisdileo]

Nathan Lively thanks for the reply!
I was referring to a two-element end fire, and I understand the intention is to direct the energy at a 45° from the stage. Maybe I was unclear on the specifics of when this configuration would be implemented, after watching the video again I have a better understanding.
My initial comment was an idea to smooth out the coverage pattern in the middle (specifically regarding that 100hz null front & center).
Just stumbled upon your videos a few weeks ago and have been loving them. Thanks for the awesome content!

[@Zamsky39]

I don't really see how that would be better than just having a 3 element cardioid array in the middle of the stage, if there's space for that.

[@le-chris]

If you have audience far from stage at the 45° position, you need to figure out a way to get energy to them.
If you were using center subs to get the necessary amount of energy to them, any audience in front of the center of the stage would be exposed to really high sound pressure levels.

[@nathanlively]

Hey Zamas, that's a great point. I think the idea here is just to have more options for creating different results. A single 3-element inverted gradient stack creates a coverage angle of about 180º, which might not be appropriate for every situation.

[@AllanKendall]

Dave at Rat sound has a post about using this with the Chilli Peppers, I’m interested in your ‘acceptable’ level of level disparity per freq front to back, side to side, do you have a working threshold? Also the age old question of balancing tops (specifically line array) with Subs!

[@nathanlively]

Sure. The best broadband F2B rejection I've seen is with a 2-element inline gradient array: 30dB in MAPP and 17dB in the field indoors. That's why 6dB doesn't seem like much to me. Still helpful, though!

[@AllanKendall]

@@nathanlively thank you Nathan, how about out front - cardioid cabs aside, I guess I'm asking the power alleys created by subs (L/R, LCR, etc etc.) if you can even out the troughs is there an acceptable medium? eg. as long as the subs are +-6db front to back. Sorry Im not great at articulating my question!