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Author Topic: Could someone explain this sub placement advice?  (Read 8239 times)

Chuck Simon

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Re: Could someone explain this sub placement advice?
« Reply #20 on: November 02, 2015, 02:14:21 pm »

Auh huh!  I missed the "end to end" part in his earlier post.  Now it makes sense.

The original post was referring to a conventional side by side arrangement.
« Last Edit: November 02, 2015, 02:17:23 pm by Chuck Simon »
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Bob Faulkner

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Re: Could someone explain this sub placement advice?
« Reply #21 on: November 02, 2015, 03:40:49 pm »

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.
Exactly!

I used to center cluster subs, but it never sounded right; then after discovering/using Meyer's MAPP software, I was able to "see" what was going on... from then on, the subs have always been spaced.  The physics is a lot of fun; just wish I had better tools and more time for it.
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Chuck Simon

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Re: Could someone explain this sub placement advice?
« Reply #22 on: November 02, 2015, 04:50:11 pm »

Bob, are you still confusing "end to end" with "side by side"?  Most people are stacking side to side when they center cluster and are experiencing a gain in output - not the issues you are talking about.  I center cluster when practical and the additional gain is obvious!
« Last Edit: November 02, 2015, 04:54:27 pm by Chuck Simon »
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Stephen Kirby

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Re: Could someone explain this sub placement advice?
« Reply #23 on: November 02, 2015, 05:18:43 pm »

I worked this out some years ago and can't remember the exact number but I had done some street festivals where I spaced the subs out along the front so that the interference at 60Hz created some steering effect keeping the kick drum down the middle of the street and out of the store fronts on either side to some degree.  It also meant that there was nowhere on stage to escape it.  I gave up the output of coupling for the steering.  Probably had lots of secondary lobes in the middle but it was better than a power alley with holes in front of each main where audience was and bass out to the sides as well.
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Steve Garris

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Re: Could someone explain this sub placement advice?
« Reply #24 on: November 02, 2015, 05:27:05 pm »

Bob, are you still confusing "end to end" with "side by side"?  Most people are stacking side to side when they center cluster and are experiencing a gain in output - not the issues you are talking about.  I center cluster when practical and the additional gain is obvious!

Looking at Johannes picture, it looks like they're both facing forward, about 30" apart, with about 6 feet between them in the center. I would call this side-by-side, but I wasn't aware that the 80 cm (30") spread between them would be helpful.
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Bob Faulkner

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Re: Could someone explain this sub placement advice?
« Reply #25 on: November 02, 2015, 06:00:37 pm »

Bob, are you still confusing "end to end" with "side by side"?  Most people are stacking side to side when they center cluster and are experiencing a gain in output - not the issues you are talking about.  I center cluster when practical and the additional gain is obvious!
Hey Chuck - ah, I see what you are saying... I should be using the term "side by side" when describing how I used to have the subs centered.  Yes, when I center cluster, I do get additional gain, however with the subs spaced apart (side by side) by a few feet, the additional gain is more noticeable around the 50hz range, which is what I'm looking for.  When the subs were centered "side by side" next to each other, there was a perceivable increase in gain, however, it was not in the bass range (~50hz) that I was needing.  The MAPP prediction software help me see the differences in db per freq. range as the subs move from center (side by side) to far stage left/right.  For my system, the "sweet spot" is about 12' on center separation between cabinets.

Sorry for the confusion.
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Luke Geis

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Re: Could someone explain this sub placement advice?
« Reply #26 on: November 02, 2015, 06:28:07 pm »

I will try this and see if it makes sense to you:

1. Stereo deployment, like you did above = power alley up the middle, lots of comb filtering and semi predictable coverage, is aesthetic looking and you are used to it's sound.

2. Center cluster on the floor ( side by side ) = good coupling and controllable coverage depending upon length and spacing. Lots of splash onto the stage and nearly impossible to align to the tops 100%, but the sub energy is solid and even.

3. End fire array = steerable sub control depending upon length and spacing with a cardiod pattern. Requires a deep space and does not work as well when placed under a stage. Still cannot be aligned 100% to the tops, but enhances the results from #2.

4. Center clustered virtual arc = the subs are still in line, but are progressively delayed as you get to the ends creating a virtual arc. Gains some directional control in a single plane, but as can be imagined, will not align properly with the tops and is said to sound a little weird due to less than stellar box to box interaction.

5. Subs in same plane as the tops = depending upon deployment ( center or stereo ) will exhibit the same relative results with one added downside. Floor bounce. This is where the sub energy is reflected off the floor and becomes destructive interference, degrading the performance. The one up side is that coverage to the FOH is more like the tops.

6. Cardiod sub array = A good way to get a cardiod pattern with subs in a plane that works well with aesthetics and typical stage setups. The downside is you don't get as much addition and it requires more elements to have that control. It is a two steps forward, one step back approach. It works well and has a good compromise between #2 and #3 aside from needing more speakers. This is one of the more popular deployment methods these days for larger companies with the inventory.

Subs are about the only thing that we can play with that can make a huge difference. Obviously the tops are pretty much a given if deployed in stereo. Having a goal is what sets the performance scale for us individually. We want this result, and we either get it or not? The six ways of deployment mentioned are only a small number of ways that can be done. There is slot fire arrays, V fire arrays, Crossfire arrays and even arrays that have control in both the vertical and horizontal plane. NONE of them are able to work 100% with the tops, but can enhance the performance far beyond that goal alone. You want to keep sub energy off the stage, you will have to run an array of some sort. You want even coverage over the whole venue while keeping energy off the stage, you will have to run a crazy sub array of some sort. How the stage is made and the venue itself can impact the sub array design. It will always be a compromise and there is not necessarily one best way.

So the experienced " Lighting Guy " says this is the way to do it? Perhaps so? Unless you know what result your looking for, you have no measurement in which to scale against. At the entry level, or lets say little guy level, it is not as important which way it's done because the results are about the same. Typically there is only two subs and they are either set up in stereo, or in the center of the stage as a cluster. The later is probably the better of the two in most cases, but that is 100% dependent upon the venue and stage? At the entry level, your not taking advantage of physics as much as you are your ability to work around a problem.

Your ability to get a good result is more than likely based upon your knowledge of sound in general. The physics play a large part in making it easier, but crap in is still crap out. Since most systems at that level are set up relatively the same, you only have to be better than the next guy at sound, more so than physics. Better gear and deployment make the job easier and acquires better results, but it doesn't say anything for your ability to produce good sound. I say that a monkey could twist the knobs and make things sound great, but can he set it up from scratch and design a system that will get him their on his own? If you start with a great system that is deployed well, the other part is a lot easier. If you can make 7 out of 10 people happy, your doing pretty good. Sound is subjective and what one thinks is amazing another thinks sounds like crap. The system as a whole does not have to be perfect, but having each part of it do what you intend for it to, is a great step forward. That is where the physics and the goals come in. Chances are good that a system that is 80% perfect ( in terms of measurable performance ) is better than not knowing a performance standard at all?
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Jamin Lynch

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Re: Could someone explain this sub placement advice?
« Reply #27 on: November 02, 2015, 06:45:37 pm »

I have a couple of venues where I often supply sound. I've tried different sub setups and the basic L/R placement seems to be best to my ears. Center clustered didn't really work....at those locations.
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Ivan Beaver

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Re: Could someone explain this sub placement advice?
« Reply #28 on: November 02, 2015, 07:21:49 pm »



2. Center cluster on the floor ( side by side ) = good coupling and controllable coverage depending upon length and spacing. Lots of splash onto the stage and nearly impossible to align to the tops 100%, but the sub energy is solid and even.


I would argue that in many cases the sub coverage is far from "even" with center clustered subs.

It is MUCH louder close to them, than when further away.

That is not "even" to me.

Even (at least to me) means the same SPL and freq response everywhere.

Now if you mean not as many "peaks and valleys" then that can be true-depending on the particular room.

But sometimes these "peaks and valleys" even out the overall response-especially indoors, where the room itself adds a whole new set of room modes to the equation-REGARDLESS and independent of the sub setup.
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duane massey

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Re: Could someone explain this sub placement advice?
« Reply #29 on: November 02, 2015, 09:16:34 pm »

Interesting thread. Just curious: would the type of sub (bent horn, straight horn, vented box, etc) make a difference in placement options?
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Duane Massey
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ProSoundWeb Community

Re: Could someone explain this sub placement advice?
« Reply #29 on: November 02, 2015, 09:16:34 pm »


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