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Author Topic: subs and deploying them 'in the round'  (Read 93893 times)

Jim Mullen

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Re: Measurements (cont)
« Reply #60 on: January 11, 2005, 03:11:15 PM »

Do I understand your suggested stacked configuration correctly? 2x2 stacked, with one set facing the opposite direction, and delay the front firing set based upon 1/4 wave length for whatever center frequency one might prefer, i.e. for a 60 hz center frequency 4.7 msec delay (1129 ft/sec / 60 hz / 4) to the front stack?  No polarity reversal involved, correct?  Thanks much to all.
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Jim Mullen

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Re: Measurements (cont)
« Reply #61 on: January 11, 2005, 03:16:07 PM »

Oops, I didn't complete the math.  1/4 wave of 60 hz equals 4.7 feet, equals 4.163 msecs of delay, right?  Thanks.
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Langston Holland

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Learning
« Reply #62 on: January 12, 2005, 09:50:32 PM »

Harford Sound wrote on Mon, 10 January 2005 15:37

What is MAPP or whatever those graphs are and how do you get the results? Could you explain what everything means on them? Thanks!


Send me a personal note if you have specific questions, but if you're looking for general advice, this is what I'd do:

1. Sign up for the back-to-back Syn-Aud-Con sound reinforcement seminars in Feb. or Apr. There is simply no excuse for missing this resource. It'll put you out about $1,500 total, which will be the best deal you'll ever get on anything in your life. It will unlock doors for you that you never knew existed. Do this before passing GO.

http://www.synaudcon.com/sched.htm

2. After you pass GO, support the industry and your brain by purchasing something like Smaart and LARA and reading every page of the manuals. You can only learn so much via books and articles, the doing of the theory is where learning really happens.

http://www.siasoft.com
http://www.integralacoustics.ca
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Mike Babcock

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Re: subs and deploying them 'in the round'
« Reply #63 on: January 12, 2005, 11:59:43 PM »

Harford Sound wrote on Mon, 10 January 2005 16:37

Man.. What an interesting thread. I started off reading not having a clue what was going on, but now Im starting to get it. I think Im going to have to read it a few more times to truely understand everytinhg. But I have a question. What is MAPP or whatever those graphs are and how do you get the results? Could you explain what everything means on them? Thanks!


I feel sorry for the animals in the woods of those pics. That must be a lot of sound. Smile


Hello

MAPP is a program developed by Meyer Sound for Meyer Sound products. You place speakers in the program where they are planned to go, it will send that information to a supercomputer in CA and it will compute how those speakers will interact with each other at a specific frequency.
What you are seeing is a visual representation of SPL of a certain frequency. Since I was dealing with subs, I felt that 63Hz was appropriate. If you look at the key on the right hand side of the picture, It shows maroon (dark red) as 0 db, that is the place where 63hz is at the maximum loudness it can be. If you just look at the red areas, that is where you will find good reproduction of 63 hz. If you then look at the blue areas, that is where you will not be hearing much 63 hz. If you see streaks of blue and red, you can safely say that there will be power alley issues and those speaker boxes placed where they are at that point in time will have destructive interference in some areas. Adjusting the position, relative levels and delay times in the program can put that destructive interference in a more opportune spot.
The Cardioid Sub theory in use is basically manipulating (both position and phase) 2 or more subs so that it adds in one direction and subtracts in another.
Additionally, I did not use Meyer products for this particular show, so I picked Meyer models that were about the same vintage and polarity pattern of the speakers that I did use. It is not a perfect match, but I could figure out from my experiences with both types of speakers the difference from the program to real life.
I hope that makes things a little (a lot) clearer. If you have any additional questions, please ask.

Mike Babcock

(edit)PS: the reason behind my post was not initially to discuss cardioid subs and the theory behind it. That became a nice added part of it. The main reason was to tell everybody to learn all they can about everything audio (or lighting if you swing that way) from attending seminars and training courses. The knowlege I gained at one seminar thwarted a major problem I would not have known about until I was on the job site and I would not have even had the knowlege of how to fix it without the knowlege I gained from Mauricio and Meyer. The lab is a wonderful learning tool, and I know some didn't even know cardioid subs existed before this thread, and most probably had no clue how to deploy it. I'm not too worried about my competitors learning "tricks" from my post here, if they upgrade their service to the client, I will one up them by learning more and making my service better.
The industry as a whole needs to step up. As someone who barks and has a whole lot of trademarks Smile posted on a blog, (paraphrased here) Anyone can drop some money on a prepackaged system, read the manuals and call themselves a sound company. We all need to learn how and why things work.
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Tom Reid

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Re: subs and deploying them 'in the round'
« Reply #64 on: January 13, 2005, 07:42:29 AM »

And this thread just keeps getting better.
Thanks to everyone for raising that bar.
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Stephen Robertson

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Re: subs and deploying them 'in the round'
« Reply #65 on: January 13, 2005, 11:17:18 AM »

Hey Langston, gonna go out on a limb here, you wouldn't happen to be the provider for Big Daddy Weave would you?

Sorry for going OT

Stephen
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Big Mig

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Re: subs and deploying them 'in the round'
« Reply #66 on: January 14, 2005, 04:18:55 AM »

Has anyone else tried 'hypercardioid' sub arrays? we ran a block of 3 deep x 2 wide subs each side of the stage at a festival build in the UK (as a test) as we needed attenuation to the side (both on and off stage) and didn't really care about spill behind the wings. It worked beautifully although the PM had a fit when he saw the subs laid out across the security pit!

MAPP plot shows one side - I'm working on how to combine this and cardioid arrays to isolate a festival or arena stage even better. Spacing was 1/4 wavelength at 100Hz between rows 1,2 and 3 with 2.5ms delay on row 2 and 5ms on the front row (no polarity swap) with physical spacing of 1/2 wavelength at 100Hz between columns. In an ideal world we'd have used 3x3.

One thing though - this technique doesn't improve the subs themselves... if I'd had access to the beasts we would now use, things would have been even more impressive.

index.php/fa/958/0/
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Dr. Don

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Re: subs and deploying them 'in the round'
« Reply #67 on: January 14, 2005, 01:12:39 PM »

Hey Mike:
Thanks for starting this great thread. I'd like to add a note and a war story.

It is important to note that this only works if the sub woofers are run in their linear range. As soon as the sub woofers are driven into overload and distortion, all steering theory breaks down, and pattern control is lost. Also, remember some brands of sub woofers have non-linear distortions even when they are not operated in an overload condition so pattern control would never work.

As a war story to do with steering of low frequencies, in the early 1990’s John Meyer, Jamie Anderson, and myself experimented with steering sub woofer patterns. We (Grateful Dead) were playing large stadiums and to trying to get thorax-rattling (make your pants legs flap in the breeze) frequencies to the upper deck at the far end of the venues. We had sixteen Meyer Sound 650’s stacked on end on either side of the left/right PA stacks. That’s thirty-two eighteen-inch speakers straight up in a column on either side. Phil Lesh (the bass player) freaked and couldn't deal with the sub level on stage. In order to overcome this issue, we first decoupled the PA wings from the stage by making them free standing. That only had a minor effect, so John came up with an idea to apply some noise-canceling theory. Using a FFT analyzer, we measured the frequency response at Phil’s position on stage and stored it in the analyzer. Then we flew two 650’s in a column on either side of the stage as side fill. Next, using a phase correct parametric equalizer we exactly matched the low frequency of the side fills to the stored response of the mains. Then, while looking at the phase response, we introduced delay on the side-fill speakers until the phase traces were an exact match. Finally, we swapped the polarity of the side fills. This was a great solution, and the sub level on stage issue never raised its ugly head again.

Dr. Don (The Newbie)
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Brad Harris

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Re: subs and deploying them 'in the round'
« Reply #68 on: January 14, 2005, 04:12:47 PM »

Hi there Dr. Don,

I've enjoyed reading your posts in the archives, but I'm curious as to what effects of having the bass player happy with the sub level at his position did to out in FOH?

Of was it just such an enourmous venue that it really didn't do too much detrimental effects? (I can only imagine 16 650's stacked! more-or-less one inventory of a company that I freelance for!)
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Brad Harris

Langston Holland

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Re: subs and deploying them 'in the round'
« Reply #69 on: January 14, 2005, 04:45:10 PM »

Fascinating. But so is the rest of the Dead's reinforcement history. Wish whoever did their sound would write a book on it... :)

I've been very impressed with Jamie's contributions at SIA Soft - he's taught me quite a bit - you are no small legend over there as well.

On the side fill subs: I can see this working nicely for Phil and the fact that you only used 4 650's vs. the other 32 certainly prevented a material distortion of the house array. Do you remember approx. how far Phil could move around before he left his Maxwell Smart cone of silence? As you recall, Max and the Chief couldn't move very far at all. :) Were the others hammered with even more bass than before the sub side fills were flown?
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Re: subs and deploying them 'in the round'
« Reply #69 on: January 14, 2005, 04:45:10 PM »


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