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Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?

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Bennett Prescott:
I feel I should add that conventional cardioid arrays, as mentioned by the OP, have the SPL tradeoff in favor of compactness and reliable pattern. End-fire arrays, as mentioned by everyone else, do not suffer from a loss of forward SPL but do suffer from unreliable pattern control and a much larger physical footprint.

Once you get into large subwoofer arrays, regardless of whether you build in any "extra" directionality or not, you had better have a pretty good handle on how phase operates. It's not just about how the array(s) interact with itself/themselves, but also how they interact with the mains at crossover.

If you're not careful, you can end up with three power alleys, an extremely narrow pattern from your ground-stacked subwoofers, and cancellation that happens at varying audience depths. Solving the traditional left/right stacked subwoofer power alley problem for large PA systems is non-trivial. Modeling is your friend!

Charlie Hughes:
Very nice illustration of what's going on Harry.  I would like to make a couple of comments to clarify things.

HarryBrillJr. wrote on Fri, 15 January 2010 01:59
http://www.tigeraudioinc.com/endfire2.jpg
Better rejection of more frequencies in the rear, and better overall control, less impact.
The image in the link above illustrates a cardioid set-up.  Not an end-fire array, per se.


HarryBrillJr. wrote on Fri, 15 January 2010 01:59
http://www.tigeraudioinc.com/endfire.jpg
Better impact, but less control.
The image in this link is of an end-fire array.

More sources (subs) can be added to the end-fire array, with each one delayed to the end source (sub).  The result of adding more sources with the appropriate delay is tighter pattern control.

HarryBrillJr.:
Charlie Hughes wrote on Fri, 15 January 2010 16:17
Very nice illustration of what's going on Harry.  I would like to make a couple of comments to clarify things.

HarryBrillJr. wrote on Fri, 15 January 2010 01:59
http://www.tigeraudioinc.com/endfire2.jpg
Better rejection of more frequencies in the rear, and better overall control, less impact.
The image in the link above illustrates a cardioid set-up.  Not an end-fire array, per se.



Thank you for the comments Charlie.  I expected someone to reply.
I fundamentally disagree with that naming scheme, although I go out of my way in class to mention that people "call" that deployment cardioid.  It's all about communication.  Cardioid is a POLAR PATTERN, end fire is the deployment (or array) used to achieve that polar pattern.  No need to argue, we can agree to disagree on that.  The 4 deep end fire is also cardioid and even approaches super cardioid although it varies by frequency.  I think all of these implementations should have names.  What they are named, I don't care, but cardioid (or any other polar pattern description should not be one of the names.  It's very confusing for the average sound guy like me.
At the show I'm currently working they deployed an "omni sub array."  That doesn't describe the way the cabinets are stacked, just the polar pattern, which is the result of that deployment.

I don't see anything controversial about it.

Justin Sumrall:
Bennett Prescott wrote on Fri, 15 January 2010 02:14
What's controversial about it?



Looks like that has been proven  

Jerome Casinger:
How is it that between endfire and endfire2 links everything is the same except you flip the polarity on endfire2 but get the same result as the first link. If you have everything set up the same as shown in the two links but then flip the polarity in one of them would that cause cancelation unless you turned and pointed one sub backwards?

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