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Author Topic: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?  (Read 65403 times)

Greg Longtin

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Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #10 on: January 16, 2010, 09:13:48 am »

Jerome,

Sorry, I don't think anyone implied the two methods are the same.

EndFire2 - Alternative Method - Cardioid

 1. 'perfect' on axis *rear* cancellation, front has a comb effect

 2. From the rear, acoustic alignment of two *out* of phase sources

 3. At VLF, 360 deg response is cancellation


EndFire - End Fire

 1. 'perfect' on axis *front* summation, rear has a comb effect

 2. From the front, acoustic alignment of two *in* of phase sources

 3. At VLF, 360 deg response is summation

Greg
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HarryBrillJr.

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Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #11 on: January 16, 2010, 01:05:26 pm »

They are not the same.  In addition to having the rear polarity inverted, the rear is also delayed.
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Harry Brill Jr.
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Jerome Casinger

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Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #12 on: January 16, 2010, 10:22:10 pm »

Greg Longtin wrote on Sat, 16 January 2010 08:13

Jerome,

Sorry, I don't think anyone implied the two methods are the same.

EndFire2 - Alternative Method - Cardioid

 1. 'perfect' on axis *rear* cancellation, front has a comb effect

 2. From the rear, acoustic alignment of two *out* of phase sources

 3. At VLF, 360 deg response is cancellation


EndFire - End Fire

 1. 'perfect' on axis *front* summation, rear has a comb effect

 2. From the front, acoustic alignment of two *in* of phase sources

 3. At VLF, 360 deg response is summation

Greg



Got it, thanks for the clarificiation!
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Justin Sumrall

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Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #13 on: January 16, 2010, 10:40:11 pm »

Thanks guys. If Dave Rat is out there, id love to hear your take on it!
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Tim McCulloch

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Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #14 on: January 16, 2010, 11:59:23 pm »

Justin Sumrall wrote on Sat, 16 January 2010 21:40

Thanks guys. If Dave Rat is out there, id love to hear your take on it!


DR's take on what?  He's very into LF arrays of various types and has (and is) writing about them extensively on his blog.  He has strong opinions about some of the methods, both positive and negative.

You might want to read his blog on ratsound.com as he's discussed both of the methods Harry illustrated.

Have fun, good luck.

Tim Mc
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Bob McCarthy

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Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #15 on: February 01, 2010, 01:47:12 pm »

I posted to my blog two of the figures from the 2nd ed of my book that show how the phase response steers the end-fire array. The pic shows how the spacing and delay sync in forward direction and scramble in the rearward direction.index.php/fa/27786/0/

Here is one of the pics here. (limit is 1 pic)
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Art Welter

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Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #16 on: February 01, 2010, 07:12:34 pm »

Bob,

Wow, a life size sub diagram  Laughing !

What are the dB differences between each color contour?

How well do real world measurements compare to the prediction?

index.php/fa/27808/0/
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Bob McCarthy

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Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #17 on: February 01, 2010, 07:28:46 pm »

Art,

I agree the pic did come out really big here. Is this Texas?

The colors on the MAPP plot are 3 dB per shade.

The real world measurements of such things confirm what we see here - BUT it is much harder to see so clearly due to the presence of reflections etc, which is something we never get away from in subwoofer world

6o6
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Rog Mogale

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Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #18 on: February 02, 2010, 12:42:02 am »

Hi,

I’ve done some basic playing around with cardioid setups and other bass arrays. Here’s some links to a few papers that might help.

http://www.voidaudio.com/pdf/bass%20guide.pdf

http://www.voidaudio.com/pdf/lffaq.pdf

http://www.voidaudio.com/pdf/trucksim.pdf

http://www.voidaudio.com/support.asp




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Adam Schaible

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Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #19 on: March 27, 2010, 11:10:53 pm »

Sorry to dig this up... but curious about what you folks think.

With 8 subs, is this about as good as it gets?

63hz shown, no boundaries (outdoor show)

index.php/fa/29024/0/
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