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Author Topic: Could someone explain this sub placement advice?  (Read 8530 times)

Luke Geis

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Re: Could someone explain this sub placement advice?
« Reply #10 on: November 02, 2015, 01:54:40 am »

Unfortunately the status quo for speaker deployment is not necessarily built around sound practices and scientific data. Most put the subs on each side because it looks appealing. The problem with subs is that no matter which way, or how you deploy them, they will have a weakness or downside to that deployment. Getting the subs up in the same plane as the tops will have floor bounce. Putting them in the center of the stage in a line makes aligning them to the tops nearly impossible at any given spot. Placing them in the conventional stereo setup has the power alley and lots of comb filtering. Either way you have some downside.

So as Ivan has mentioned, you have to know what your goal is, then you can create a plan for execution and hopefully have success. I lately have been a fan of simply placing the subs in a centralized location. If I have to do stereo setups with the subs on each side, I will simply turn one side off and use it for looks. The beauty of subs is that localization is difficult below 80hz. So while it may not be aligned correctly for the opposite side, the one sub will line up well for one of the speakers and it won't really be noticed that the other side is not on. This is of course dependent upon the spacing of the system. A very large, wide stage won't do well with that idea. So it is really a matter of depends. Sometimes having the subs deployed in a matter in which cancellations occur is helpful. You can get the lobes to hit where you want them to and can even get cancellations to occur likewise. Playing with software like Rayend can help get you in the ballpark and then a bit of time in the field will nail down the actual deployment based on that model. So basically study up, design a plan, execute and adjust till you get success.
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Johannes Halvorsen

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Re: Could someone explain this sub placement advice?
« Reply #11 on: November 02, 2015, 02:21:13 am »

I think I wasn't precise enough in my initial question. To clarify:

I got the advice from someone knowledgeable who has tons of experience running sound in this very venue. The deployment worked fairly well. What I'd like to know is WHY it works. What qualitys do you lose and gain with this layout, and why?

I'm here to learn; hence to ask stupid questions.   :)

Here's a pic of the setup.

 

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Jamin Lynch

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Re: Could someone explain this sub placement advice?
« Reply #12 on: November 02, 2015, 07:20:58 am »

I think I wasn't precise enough in my initial question. To clarify:

I got the advice from someone knowledgeable who has tons of experience running sound in this very venue. The deployment worked fairly well. What I'd like to know is WHY it works. What qualitys do you lose and gain with this layout, and why?

I'm here to learn; hence to ask stupid questions.   :)

Here's a pic of the setup.

 

He was probably trying to spread the subs just far enough apart to where they still couple and give good coverage, but not so far apart as to create comb filtering or a power alley down the middle.

From what you have said, it must have worked.

Working the same venue gives you the advantage of trying different set ups to see what works best.
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Ivan Beaver

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Re: Could someone explain this sub placement advice?
« Reply #13 on: November 02, 2015, 07:35:43 am »

It's a children's Halloween party. Might not be a bar.  :)
Even more reason to HAVE A BAR there :)
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Ivan Beaver
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Ivan Beaver

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Re: Could someone explain this sub placement advice?
« Reply #14 on: November 02, 2015, 07:43:04 am »

I think I wasn't precise enough in my initial question. To clarify:

I got the advice from someone knowledgeable who has tons of experience running sound in this very venue. The deployment worked fairly well. What I'd like to know is WHY it works. What qualitys do you lose and gain with this layout, and why?

I'm here to learn; hence to ask stupid questions.   :)

Here's a pic of the setup.

 
you still have not provided any information as to how large of a space you are looking to cover.  I see part of a gym, but it might be a multiple gym etc, we have no idea.

It looks like you might be trying to cover a wide area-due to the placement of the tops-but we can't be sure.

At some freq you will get addition, at other freq you will get cancellation.  What is more important?

Often in highly reverberant situations, a directional sub configuration can be a big help in reducing the "reverb" of the subs.

Again-it all depends on what you are trying to achieve in THAT particular setup.

Tomorrow could be completely different.
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Jamin Lynch

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Re: Could someone explain this sub placement advice?
« Reply #15 on: November 02, 2015, 07:58:21 am »

Even more reason to HAVE A BAR there :)

So true. Especially for sugared up kids!!
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Chuck Simon

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Re: Could someone explain this sub placement advice?
« Reply #16 on: November 02, 2015, 08:10:15 am »

Quote
With their closest positions, the coverage (and levels) were noticeably less on both the software and during an actual event.
 

Now that's the statement that has me stumped.  It goes against everything I have experienced and just about everything I have read. Assuming that they are wired with proper polarity, how can placing speakers together result in less "levels"?
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Bob Faulkner

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Re: Could someone explain this sub placement advice?
« Reply #17 on: November 02, 2015, 11:42:05 am »

 

Now that's the statement that has me stumped.  It goes against everything I have experienced and just about everything I have read. Assuming that they are wired with proper polarity, how can placing speakers together result in less "levels"?
Had I saved the output from the software, I would show you.  (thinking cap on) -- The level differences and overages were frequency specific; i.e there was a good increase in db around the 50hz (I think it was 50hz) range at 60' out with the subs separated about 12' on center.  Though, with the same subs pushed to the center (end to end) using the same 50hz, produced noticeably less output out front (~-12db).  I tested this during sound-check at an event and it appeared accurate; ever since then, I keep the subs apart.  (thinking cap off)

Though, using different sub frequencies yielded relatively same results... some frequencies did better with the subs pushed together, others did better with them apart... which too far apart started producing comb-filtering and emphasizing the power-alley (neither of which I was looking for). 

I couple my subs to get the best coverage.  Though, I rarely center the subs end-to-end, and hardly ever space them to stage-left/right (with the mid/highs).  Somewhere between the center and stage left/right is where they pretty much sit.

Would love to find other prediction software like Meyer's (MAPP), but needs to be for Linux. 




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Chris Hindle

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Re: Could someone explain this sub placement advice?
« Reply #18 on: November 02, 2015, 01:00:27 pm »

Had I saved the output from the software, I would show you.  (thinking cap on) -- The level differences and overages were frequency specific; i.e there was a good increase in db around the 50hz (I think it was 50hz) range at 60' out with the subs separated about 12' on center.  Though, with the same subs pushed to the center (end to end) using the same 50hz, produced noticeably less output out front (~-12db).  I tested this during sound-check at an event and it appeared accurate; ever since then, I keep the subs apart.  (thinking cap off)

Though, using different sub frequencies yielded relatively same results... some frequencies did better with the subs pushed together, others did better with them apart... which too far apart started producing comb-filtering and emphasizing the power-alley (neither of which I was looking for). 

Not to put too fine a point on it, but EVERYTHING you describe here IS comb filtering. It will change depending on frequency, distance, and angle between 2 (or more) sources.  Welcome to the world of Physics ! It's a collection of laws that just can't be broken.
Chris.
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Ivan Beaver

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Re: Could someone explain this sub placement advice?
« Reply #19 on: November 02, 2015, 01:32:46 pm »

Had I saved the output from the software, I would show you.  (thinking cap on) -- The level differences and overages were frequency specific; i.e there was a good increase in db around the 50hz (I think it was 50hz) range at 60' out with the subs separated about 12' on center.  Though, with the same subs pushed to the center (end to end) using the same 50hz, produced noticeably less output out front (~-12db).  I tested this during sound-check at an event and it appeared accurate; ever since then, I keep the subs apart.  (thinking cap off)


THERE (in red) is your problem.

Unless you properly spaced them and used the proper delay-you WILL have cancellations that are based on freq by setting them up that way..

And EVEN WHEN you use the proper delay and spacing, the SPL output in either endfire or cardioid mode (rear sub out of polarity) WILL BE LOWER, than if the same total number of subs is placed side by side.

I know people do not want to believe this, but all they have to do is to measure it to see for themselves.
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Ivan Beaver
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Re: Could someone explain this sub placement advice?
« Reply #19 on: November 02, 2015, 01:32:46 pm »


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