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Author Topic: Could someone explain this sub placement advice?  (Read 8529 times)

Johannes Halvorsen

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Could someone explain this sub placement advice?
« on: November 01, 2015, 02:24:36 pm »

I ran sound for a children's Halloween party last night. I brought my churche's 4x Qsc K12 + 4x KW181. The room in question is a ~30x40m sports arena with a 20x40m floor and stroragerooms etc. with sloping seatings on top along one long side. Ceiling hight from floor level is aprox 10m I think. Walls mostly concrete, floor is cast sports floor of some plastic/rubber compound. Roof is concrete/wood. 3 room dividers extending some meters below roof.

We hired lighting from a local pro sound/lights/AV company, and the "lighting guy" gave me an advice that I don't quiet understand.

We had the tops on high stands (~3m up, tilted downwards). Scene aprox 8x4m at the middle of one long side. I was about to center all 4 subs side by side directly in front of stage, but the guy told me to place two pr. side, close to the tops, with exactly 80 cm between the two subs. That is all 4 subs in one line, in the same plane as the tops. Two subs pr side with 80 cm in between.

Since this guy is infinitely more experienced than me, and runs sound and light on huge shows for a living, I simply did as he said, and it sounded ok. He didn't explain why we should deploy this way, and I didn't push him.

As I said, this guy does this for a living and quiet successfuly so. But I haven't come across this deployment pattern before, and don't understand why it should be preferable to center clustering. Could anyone enlighten me?

(And for the record: Yes, the subs outruns the tops by a mile and a half. But angry mothers occures waaay before the K12s breaks a sweat in this room...)
« Last Edit: November 01, 2015, 02:33:26 pm by Johannes Halvorsen »
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Bob Faulkner

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Re: Could someone explain this sub placement advice?
« Reply #1 on: November 01, 2015, 05:34:23 pm »

Basically, (with all things being what they are), center clustering the subs (all together in the center) produces a lot of freq. cancellations and doesn't allow for much of "good bass" coupling to occur.  By moving the subs apart, within reason, allows for better coupling.  Keeping 80cm between the subs is doing the same as spreading the subs apart from the center.  However, spreading the subs too far apart (too far to the left and too far to the right) results in a bass power-ally to occur directly down the middle of the listening area while at the same time, producing minimal bass volume directly out in front of the bass speakers. 

The shows I do, the bass cabinets (2 x dual-18"), are centered in front of the stage with about 12ft (3.6m) between them on center.  Unless required, I never place the subs together in the center nor are they placed directly with the FOH Left/Right cabinets.

Try centering your subs with 80-90cm between them across the front; it should yield better results than centering them across the front touching each other.

It's all about physics...
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Ivan Beaver

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Re: Could someone explain this sub placement advice?
« Reply #2 on: November 01, 2015, 07:12:36 pm »

Basically, (with all things being what they are), center clustering the subs (all together in the center) produces a lot of freq. cancellations and doesn't allow for much of "good bass" coupling to occur. 
It's all about physics...
Actually it is the opposite.  Placing the subs together produces the most coupling, with the least amount of cancellations.

However that does not mean that that provides the best sub coverage for a particular venue.

Different rooms require different solutions.

One size does not fit all.
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Ivan Beaver
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Mac Kerr

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Re: Could someone explain this sub placement advice?
« Reply #3 on: November 01, 2015, 07:13:17 pm »

Basically, (with all things being what they are), center clustering the subs (all together in the center) produces a lot of freq. cancellations and doesn't allow for much of "good bass" coupling to occur.  By moving the subs apart, within reason, allows for better coupling.  Keeping 80cm between the subs is doing the same as spreading the subs apart from the center.  However, spreading the subs too far apart (too far to the left and too far to the right) results in a bass power-ally to occur directly down the middle of the listening area while at the same time, producing minimal bass volume directly out in front of the bass speakers.

Huh? The closer the drivers are together the better they couple. The closer to the floor they are the better they couple with their own reflection. The closer to the mains they are the better the time alignment between the mains and subs.

If the show is indoors the reflections from the floor, ceiling, and all 4 walls will make the room coverage map look like a waffle.

For the best integration with your mains the subs should be up high with the mains and not overpowering the folks in front while leaving the back of the room light of bass.

To get the most output, and lowest frequency reproduction they should all be in a single block on the floor.

Each method has its pluses and minuses, you need to decide which are important to you.

Mac
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Ivan Beaver

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Re: Could someone explain this sub placement advice?
« Reply #4 on: November 01, 2015, 07:16:49 pm »

I ran sound for a children's Halloween party last night. I brought my churche's 4x Qsc K12 + 4x KW181. The room in question is a ~30x40m sports arena with a 20x40m floor and stroragerooms etc. with sloping seatings on top along one long side. Ceiling hight from floor level is aprox 10m I think. Walls mostly concrete, floor is cast sports floor of some plastic/rubber compound. Roof is concrete/wood. 3 room dividers extending some meters below roof.

We hired lighting from a local pro sound/lights/AV company, and the "lighting guy" gave me an advice that I don't quiet understand.

We had the tops on high stands (~3m up, tilted downwards). Scene aprox 8x4m at the middle of one long side. I was about to center all 4 subs side by side directly in front of stage, but the guy told me to place two pr. side, close to the tops, with exactly 80 cm between the two subs. That is all 4 subs in one line, in the same plane as the tops. Two subs pr side with 80 cm in between.

Since this guy is infinitely more experienced than me, and runs sound and light on huge shows for a living, I simply did as he said, and it sounded ok. He didn't explain why we should deploy this way, and I didn't push him.

As I said, this guy does this for a living and quiet successfuly so. But I haven't come across this deployment pattern before, and don't understand why it should be preferable to center clustering. Could anyone enlighten me?

(And for the record: Yes, the subs outruns the tops by a mile and a half. But angry mothers occures waaay before the K12s breaks a sweat in this room...)
There are a bunch of "it depends", when talking about sub deployment.

What works in one situation is completely wrong in another.

Part of the answer starts with a question-"What are you trying to achieve in this particular venue?"

Is bass energy directly in front of the stage more important?

Is sub energy evenly spread around the venue more important?

Are you trying to keep the sub energy off of certain areas? Such as the bar so the bar keeps can hear orders easier.  Or some other area?

You FIRST have to start with what you are trying to accomplish-THEN look at what sort of solution would be best.

There is NO sub setup that works for every situation.  It is all a matter of compromise.
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Ivan Beaver
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Mac Kerr

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Universal truth
« Reply #5 on: November 01, 2015, 07:29:35 pm »

You FIRST have to start with what you are trying to accomplish-THEN look at what sort of solution would be best.

This should be the beginning of every answer. There is no one answer to any system configuration question, only solutions to the problem you are trying to correct.

Mac
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Ivan Beaver

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Re: Universal truth
« Reply #6 on: November 01, 2015, 08:06:20 pm »

This should be the beginning of every answer. There is no one answer to any system configuration question, only solutions to the problem you are trying to correct.

Mac
Agreed

As I often say-if you don't know what you are trying to accomplish, then how do you know if you have achieved it?

But sadly, many people just want some of result-not knowing if it is really what they are after.

But that would require making decisions, and many people want others to make their decisions for them.
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Jamin Lynch

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Re: Could someone explain this sub placement advice?
« Reply #7 on: November 01, 2015, 08:21:28 pm »

There are a bunch of "it depends", when talking about sub deployment.

What works in one situation is completely wrong in another.

Part of the answer starts with a question-"What are you trying to achieve in this particular venue?"

Is bass energy directly in front of the stage more important?

Is sub energy evenly spread around the venue more important?

Are you trying to keep the sub energy off of certain areas? Such as the bar so the bar keeps can hear orders easier.  Or some other area?

You FIRST have to start with what you are trying to accomplish-THEN look at what sort of solution would be best.

There is NO sub setup that works for every situation.  It is all a matter of compromise.

It's a children's Halloween party. Might not be a bar.  :)
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Tim Halligan

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Re: Could someone explain this sub placement advice?
« Reply #8 on: November 01, 2015, 09:58:20 pm »

...the "lighting guy" gave me an advice...

And you listened?

 ;D

Cheers,
Tim

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Bob Faulkner

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Re: Could someone explain this sub placement advice?
« Reply #9 on: November 01, 2015, 11:11:15 pm »

Actually it is the opposite.  Placing the subs together produces the most coupling, with the least amount of cancellations.

However that does not mean that that provides the best sub coverage for a particular venue.

Different rooms require different solutions.

One size does not fit all.
True - with the events I've run, placing the subs centered (yet a few feet apart) provide the best coverage.  The Meyer speaker modeling software (which disappointingly they stopped making for Linux - now I can't recall the name) showed a strong presence at 50hz with cabinets apart about 12ft compared compared to about 3' on center (sitting end to end).  With their closest positions, the coverage (and levels) were noticeably less on both the software and during an actual event. 

As mentioned previously (and is 100% true), it depends. Not one answer will work for all questions.

My response to the OP was more of a "this has worked for me, maybe it can work for you" scenario.
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Re: Could someone explain this sub placement advice?
« Reply #9 on: November 01, 2015, 11:11:15 pm »


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