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Author Topic: subs and deploying them 'in the round'  (Read 85499 times)

Mike Babcock

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subs and deploying them 'in the round'
« on: January 03, 2005, 01:36:54 pm »

Hello Labrats

I was contracted to do an in the round show with a major "A" level act in a large NHL Hockey arena for a high brow New Years Eve party. That is as specific as I will put it, since the names are meaningless in this thread and if you want to know you can search the internet.

I'm going to backtrack for a second. About a month ago I attended a seminar taught by Mauricio Ramirez of Meyer Sound. In this seminar we were told the theories behind line array systems (subs included) and included in this was a whole section on cardioid subs. This seminar used a program called MAPP and if anyone knows it, knows it's advantages. So using MAPP at the seminar I saw sound in a light I have never quite seen it before. Things I have heard with my own two ears are visually shown on the screen backed up by explanations by Mauricio as to why it is how it is. I do not have any Meyer products in house, yet, but the theories used in MAPP can be translated to similar boxes. If anyone doesn't know, I have a fairly sizable EAW 850 inventory and not much else. But even that fact doesn't matter with the issues here.

So while preparing myself for this show I decided to use MAPP to, well, map out my rig placement, figure out how many of my boxes would cover well, find out what I would need for frontfill, etc. The problems started happening when I got to sub placement. This sub placement was how my boss wanted it. Below is my MAPP screenshot showing what I started with:
http://www.themonitorguy.com/pics/albums/userpics/10001/noncardioidmapp.jpg
http://www.themonitorguy.com/pics/albums/userpics/10001/nonc ardioidmapp.jpg
As you can see, the dark red areas have the most energy at 63 hz going to the least energy with the blue coloration. Plainly, it would have been unacceptable to have more sub energy on the stage than in the crowd. Add in the fact that the bass player for the band stands dead center and plays an acoustic bass, the FOH guy for the band would have had no end of troubles there. Flying the subs was not an option, though it would have been preferrable IMO.

So when I saw that, I started thinking about how to do a cardioid sub pattern to reduce that energy on the stage. And with the help of fellow labster Harry Brill through IMs and transferring MAPP files back and forth, and other useful insight from Phill Graham and David Buehler, we ended up with the following:
http://www.themonitorguy.com/pics/albums/userpics/10001/cardioidmapp.jpg
http://www.themonitorguy.com/pics/albums/userpics/10001/card ioidmapp.jpg

The top and bottom subs were reduced 4db in the program to simulate the area of coverage, long throw front and back, short throw to the sides. You can plainly see that the coverage was nice and even throughout with lots of cancellation on the deck. This was exactly what I was looking for, I made my case to the boss and was awarded with a "hmm, I never thought of that, go ahead" answer. Now comes reality...

Due to placement of monitor world and three guitar tech lands, I could not deploy the subs exactly how I wanted to, evenly spaced around the entire stage. So I had to adjust to a cardioid pattern of 4 wide in each corner. I do not have a MAPP of that pattern (maybe Harry can help us with that Smile ), but it acheived much the same result with a couple of cancellation lobes and power alleys. But all in all, much, much, much better than how I was originally told it was going to go. The following is a fairly dark picture of one of the sub arrays.
http://www.themonitorguy.com/pics/albums/userpics/10001/sublineSPTF2.jpg
http://www.themonitorguy.com/pics/albums/userpics/10001/subl ineSPTF2.jpg

I needed to perform the following demo for each of the techs that showed up with the band. Have them sit center stage and I turn on the inner row only of subs and have them listen, then turn the outer row of subs on and have them listen to the entire sub array. Every single one of them thought I was muting something and had to be verified by their FOH guy actually muting and un-muting to prove to them I wasn't using any mirrors of any kind. The sub cancellation on the deck was amazing and certainly worth any additional amount of time I had to take to deal with it. The band is used to traveleing with M3D subs so they do not normally have to deal with this issue.
Here's a shot of the entire rig, sorry for the graininess, camera phones kind of suck:
http://www.themonitorguy.com/pics/albums/userpics/10001/SPTFrig.jpg
http://www.themonitorguy.com/pics/albums/userpics/10001/SPTF rig.jpg

So in closing, learn what you can about doing audio if you are serious about it. This cardioid sub thing is not a new invention, and not tough to deploy, it's been around for quite some time. Even line array is not a new idea. Throwing up a bunch of boxes and saying 'close enough for rock 'n roll' is fine if you don't care. Figuring out ahead of time which tools are required is the key here. Line arrays are not always the best solution, but sometimes are. The more knowlege you have means more tools in your toolkit. Go to the Meyer seminars, join SAC, learn Smaart, go to Doug and Scovills seminar. Every little detail can and will count. Even after 15 years now, I still try to learn something new every day. Man, has it been 15 years already Wink

Mike

PS: Dave, if any of the pictures are too big, let me know and I'll trim em back, or just leave links.
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Aaron Lane

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Re: subs and deploying them 'in the round'
« Reply #1 on: January 03, 2005, 02:22:39 pm »

Dude... in a word...frikin' amazing!
Info like this is why I read this board.

Aaron Lane
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Phillip_Graham

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Re: subs and deploying them 'in the round'
« Reply #2 on: January 03, 2005, 03:23:40 pm »

First, kudos Mike B for getting "roaddog" folks to use something that looks totally wrong by the "old school" mentality.

Quote:


So when I saw that, I started thinking about how to do a cardioid sub pattern to reduce that energy on the stage. And with the help of fellow labster Harry Brill through IMs and transferring MAPP files back and forth, and other useful insight from Phill Graham and David Buehler, we ended up with the following:



For those unfamiliar with MAPP, it is a Java applet you have to sign up for at Meyersound.  You design arrays in the local applet, and then a supercomputer cluster at Meyersound calculates the array's response.  Array files are stored in XML, and can be sent to other users.  It's sort of like a more powerful version of EV's Arrayshow or RACE.

FWIW, My original suggestion to Mike was a T-shaped flow array of SB850's in the middle of the main 850 cluster.  I think the cardiod arrangement was a very clever "boss approved" arrangement.

http://www.turnofthecentury.net/sublineSPTF.jpg
http://www.turnofthecentury.net/sublineSPTF.jpg

For those unfamiliar with the "cardiod sub" technique, let me explain what is done processing-wise.  The rear row of subwoofers is delayed to line up with the spill from the front ones.  The rear boxes have inverted polarity.  The result is that the waves cancel in behind the two rows of boxes, and sum coherently in front.  The wavelength of maximum cancellation is a function of the front-to-back driver spacing.  The longer the spacing, the lower the frequency.

Mike also could have placed the two subs back to back (i.e. speakon to speakon) and then delayed the front boxes.  Or if the box was deep, like a SB1000, he could have stacked them vertically, turning every other one facing backwards, then apply the delay.

The effect is analagous to allowing some sound leak to the rear of a microphone diaphragm via the porting on a cardiod microphone.

You can do even fancier patterns than mike's but this is a good example to grasp the basics.

This technique also works in other configurations.  In your narrow "shoebox" proscenium soft-seater, you can do a horizontal line array of subwoofers across the front of the stage area to eliminate power alley, and then do a second line of subs, like mike has done, to keep the energy from spilling off the back of the subs onto the stage.

Edit:  I was going to draw the above in MAPP as an example, but it appears that past LAB-rat Harry Brill already did it for me.  Please see the attached PDF file for pictures of a horizontal sub line array+cardiod model.
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Rex Ray

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Re: subs and deploying them 'in the round'
« Reply #3 on: January 03, 2005, 04:38:41 pm »

Mike,You guys rock! Congrats on a cool solution to an all-too -common problem in "in the round" shows!
Rex(useta mix Kenny Rogers in tha round) Ray
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John Chiara

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Re: subs and deploying them 'in the round'
« Reply #4 on: January 03, 2005, 04:40:27 pm »

gtphill wrote on Mon, 03 January 2005 20:23


This technique also works in other configurations.  In your narrow "shoebox" proscenium soft-seater, you can do a horizontal line array of subwoofers across the front of the stage area to eliminate power alley, and then do a second line of subs, like mike has done, to keep the energy from spilling off the back of the subs onto the stage.


Or buy a bunch of SPL BDeaps!.

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Jason McLaurin

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Re: subs and deploying them 'in the round'
« Reply #5 on: January 03, 2005, 04:50:18 pm »

Hi Mike,

Great case study.

I did an almost identical show on new year's eve, arrayed like your "bad" example.  My mon beach was right in that dark red spot behind a corner array... talk about getting your bell rung.  There's nothing like spending the first 10 seconds of 2005 chasing down RF's so that they don't drive off the rink in the rappers' Mercedes  Rolling Eyes

Have you done any of the same modeling for standard ampitheatre / end stage setups?  I wonder if that technique would still be worthwhile when the performers aren't directly behind the subs.

-Jason  
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Chris Cowley

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Re: subs and deploying them 'in the round'
« Reply #6 on: January 03, 2005, 04:56:17 pm »

heh - that's cool  Shocked
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Owen Orzack

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Re: subs and deploying them 'in the round'
« Reply #7 on: January 03, 2005, 05:02:31 pm »

It also works very well if you are not in the round. (sheds, theatres, arenas)

If you are able to have a simple way to do it (such as with a DSP contolled amplifier) you can do it on tour, every day with great results.

http://www.dbaudio.com/pub/files/TI330.PDF

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Phillip_Graham

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Re: subs and deploying them 'in the round'
« Reply #8 on: January 03, 2005, 05:04:48 pm »

Jason wrote on Mon, 03 January 2005 16:50

Hi Mike,

Great case study.

I did an almost identical show on new year's eve, arrayed like your "bad" example.  My mon beach was right in that dark red spot behind a corner array... talk about getting your bell rung.  There's nothing like spending the first 10 seconds of 2005 chasing down RF's so that they don't drive off the rink in the rappers' Mercedes  Rolling Eyes

Have you done any of the same modeling for standard ampitheatre / end stage setups?  I wonder if that technique would still be worthwhile when the performers aren't directly behind the subs.

-Jason  


Jason,

There's always an advantage to using it, namely increasing the amount of sound in the forward lobe.  Since energy is conserved, all the energy that would normally be spilling away is focused into the main audience.  A typical standard sub setup "wastes" close to half the energy due to spill behind the stage.  This puts (some of) that sub energy into the audience, giving you more headroom.

Also, you may find the reduced low end wash on stage will allow for lower monitor levels, or not.  Rolling Eyes

It won't fix power alley issues, for that you still need center clusters, horizontal line arrays, distributed clusters, or delay shading.  You can combine the cardiod subwoofer technique with these other techniques to work on both issues.
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Re: subs and deploying them 'in the round'
« Reply #9 on: January 03, 2005, 10:02:54 pm »

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Re: subs and deploying them 'in the round'
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