ProSoundWeb Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1] 2 3 ... 8   Go Down

Author Topic: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?  (Read 31908 times)

Justin Sumrall

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 70
Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« on: January 15, 2010, 01:12:32 am »

Hey Guys and Gals,

    I have been reading up on the contreversal topic of Cardiod Sub Arrays and bass steering. I get the jist that the whole point is to capture the energy that is being wasted under the stage and elsewhere in the plane and shooting it twards the audience. What I don't get is the physics behind it. I know that Dave Rat has written about this several times but I need a down to the basics explanation of how it is done and the theory behind it. If anyone has a good explanation or has and artical that you could share I would appreciate it. Thanks!
Logged

HarryBrillJr.

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1686
    • http://www.rationalacoustics.com/forums/
Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #1 on: January 15, 2010, 01:59:09 am »

A simplistic way to look at it but a good way to get started.


http://www.tigeraudioinc.com/endfire2.jpg

Better rejection of more frequencies in the rear, and better overall control, less impact.


http://www.tigeraudioinc.com/endfire.jpg

Better impact, but less control.


Some prefer to pick a higher frequency to work with.  The choice is yours.


In real life you won't get exactly 6dB gain in front compared to 1 speaker.


If you want to deploy what d&b calls a CSA array, you can simply do this.....

http://www.rationalacoustics.com/forums/showpost.php?p=1726&postcount=2


Here's a shot of that in MAPP.....

http://www.tigeraudioinc.com/csa.jpg


The LINES coming from the speakers indicate the direction that speaker is facing.

Edit: link repairs
« Last Edit: August 21, 2012, 11:00:10 pm by Langston Holland »
Logged
Harry Brill Jr.
Tiger Audio, Inc.

http://www.tigeraudioinc.com/avatar.gif

Bennett Prescott

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 8924
    • http://www.adraudio.com
Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #2 on: January 15, 2010, 03:14:44 am »

What's controversial about it? If you understand phase, it is a simple concept. If you don't, great, I need to pay my bills.

The basic question is, are you willing to sacrifice a few dB of forward output for directionality? That can be very important. Having the pattern of your sub array match your mains array is uncommon. Some of us spend a lot of time on that sort of thing.
Logged
-- Bennett Prescott
Director of North American Sales
ADRaudio d.o.o.
Cell: (518) 488-7190

"Give me 6dB and I shall move the world." -Archimedes

Tim McCulloch

  • Newbie
  • *
  • Offline Offline
  • Posts: 0
Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #3 on: January 15, 2010, 03:29:02 am »

For a different take on using delay and arraying:


http://www.jblpro.com/catalog/support/getfile.aspx?docid=234&doctype=3


Then taking the concept a bit further:


http://www.jblpro.com/catalog/support/getfile.aspx?docid=272&doctype=3


Harry's 'quick and dirty' shows you what to do.  The JBL docs give you a bit more of the 'how'.


If you own an advanced calculator and know what the buttons do, try Chapter 12 of "Sound System Engineering", 3rd, D. Davis & E. Patronis, Jr. Focal Press.  Hell, just buy the book.  And get a copy of Bob McCarthy's "Sound Systems: Design and Optimization" while you're investing in your education. 


The more I learn, the less I know.  I'm still figuring out how big a dunce I can be.  <img src="images/smiley_icons/icon_rolleyes.gif" border=0 alt="Rolling Eyes">


Have fun, good luck.


Tim Mc

Edit: link repairs
« Last Edit: August 21, 2012, 11:01:17 pm by Langston Holland »
Logged
"Will you stand by me against the cold night, or are you afraid of the ice?" Crack The Sky

Dave Sturzenbecher

  • Full Member
  • ***
  • Offline Offline
  • Posts: 136
Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #4 on: January 15, 2010, 11:05:06 am »

Bob McCarthy states on his blog that the second edition of his book goes into this topic a little more then the first.  I haven't seen this edition though.
Logged

Bennett Prescott

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 8924
    • http://www.adraudio.com
Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #5 on: January 15, 2010, 11:21:53 am »

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!
Logged
-- Bennett Prescott
Director of North American Sales
ADRaudio d.o.o.
Cell: (518) 488-7190

"Give me 6dB and I shall move the world." -Archimedes

Charlie Hughes

  • Full Member
  • ***
  • Offline Offline
  • Posts: 107
    • http://www.excelsior-audio.com/
Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #6 on: January 15, 2010, 05:17:12 pm »

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.

Logged

HarryBrillJr.

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 1686
    • http://www.rationalacoustics.com/forums/
Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #7 on: January 15, 2010, 06:51:53 pm »

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.
Logged
Harry Brill Jr.
Tiger Audio, Inc.

http://www.tigeraudioinc.com/avatar.gif

Justin Sumrall

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 70
Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #8 on: January 15, 2010, 10:30:43 pm »

Bennett Prescott wrote on Fri, 15 January 2010 02:14

What's controversial about it?



Looks like that has been proven  Very Happy
Logged

Jerome Casinger

  • Sr. Member
  • ****
  • Offline Offline
  • Posts: 304
    • http://www.ignitestlouis.com
Re: Cardioid Sub Array, Subwoofer Steering, HOW TO DO IT?
« Reply #9 on: January 16, 2010, 06:24:32 am »

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?
Logged
Pages: [1] 2 3 ... 8   Go Up
 

Page created in 0.139 seconds with 21 queries.