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Author Topic: Flown subs...pros/cons? worth the extra effort?  (Read 4741 times)

Tim McCulloch

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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #10 on: July 14, 2018, 02:04:12 pm »

I don't think anyone has directly address the full space-ness of flown subs.
The same sub on the floor is half-space and 3db louder.

Reply #6, first paragraph.
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Luke Geis

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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #11 on: July 14, 2018, 03:51:48 pm »

By TOF I meant the distance of travel and the subsequent loss in SPL associated with that. Sufficient numbers is the KEY word. If you are going to hang subs, you will need a few more than if they were ground stacked. This is why I am not a fan of systems that include subs in the same hang as the mains. There is typically not enough and they just don't come together the same.

I think it has been studied before ( and I can't remember by whom) that when it comes to subs and full space, it is of moot consideration. The problem is the locality of the listener in relation to the subs. The listener is always on a ground plane. A ground plane is an infinite baffle for all intents and purposes. This means any energy presented will load up on it. You can put subs 100' in the air and it won't matter. The sound will come down and you will hear the resultant effect of the direct and reflected sound off the ground. A small comb filter perhaps, but you will still have the effect of coupling from your vantage point. What you hear will always be 3db louder than what the actual source contributed.
 
I suppose if you were 100' in the air with the subs while listening to them, then you could more realistically factor the whole space sound of subs. When subs are hung they more evenly cover the area because the lobe is rounded off at the ends of the hang. This adds lots of energy in the center of the hang and it tapers off at the top and bottom. Since no one is typically above the subs, the front rows experience roughly the same output as those in the back rows who are in the direct plane of all the subs and experience the coupling of all that energy. The power alley and all the other lobing effects are still there, but with some clever beam steering and tuning, the nulls can be placed in aisles and the focus of energy can be very much directed where you want it most.

I am particular to ground stacked subs myself more because you get a little more mileage out of the subs ( don't need as many ) and you can play with arrays and deployments that can really make magic happen. I suppose the best deployment would be a combination flown sub array with some well placed and aligned ground stacked units as well. With subs there really is no magic bullet though. It is always a compromise. Ground stacked subs are just easier for the average sound provider to deal with. When you are doing large shows with real LA systems, flown subs is just the logical option.

Many LA / constant curvature systems have subs that are designed to be a part of the main hang. Just about all the vendors offer a system where subs can be integrated with the mains. These are the system types I am not fond of. It just doesn't work right to me.
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Helge A Bentsen

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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #12 on: July 14, 2018, 06:49:21 pm »


I think it has been studied before ( and I can't remember by whom) that when it comes to subs and full space, it is of moot consideration. The problem is the locality of the listener in relation to the subs. The listener is always on a ground plane. A ground plane is an infinite baffle for all intents and purposes. This means any energy presented will load up on it. You can put subs 100' in the air and it won't matter. The sound will come down and you will hear the resultant effect of the direct and reflected sound off the ground. A small comb filter perhaps, but you will still have the effect of .....

This one maybe?

https://www.fulcrum-acoustic.com/assets/pdf/whitepapers/comments-on-half-space.pdf
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Jean-Pierre Coetzee

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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #13 on: July 15, 2018, 05:59:42 am »

Here are some screen grabs I got from Mapp XT. In the first the sub is on the floor and the mic is 20m away. In the second I moved the sub 6 meters into the air. The floor was set to be rigid and not free space.

Draw your own conclusions.

EDIT:

I added the frequency response graph of the two positions as well.
« Last Edit: July 15, 2018, 06:09:41 am by Jean-Pierre Coetzee »
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David Sturzenbecher

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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #14 on: July 15, 2018, 06:51:22 am »

Here are some screen grabs I got from Mapp XT. In the first the sub is on the floor and the mic is 20m away. In the second I moved the sub 6 meters into the air. The floor was set to be rigid and not free space.

Draw your own conclusions.

EDIT:

I added the frequency response graph of the two positions as well.

Can you confirm that Mapp is modeling more then just the direct sound? Most modeling programs only model just this direct sound, and for this discussion we need to include the first reflection.


Sent from my iPhone using Tapatalk Pro
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Mark Wilkinson

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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #15 on: July 15, 2018, 12:13:54 pm »

Here's a good thread from the past ... on ground vs flown

http://forums.prosoundweb.com/index.php/topic,158814.0.html
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Jean-Pierre Coetzee

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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #16 on: July 15, 2018, 12:45:20 pm »

Can you confirm that Mapp is modeling more then just the direct sound? Most modeling programs only model just this direct sound, and for this discussion we need to include the first reflection.


Sent from my iPhone using Tapatalk Pro

There is a difference in phase response and polar pattern with the boundary on and the boundary off so I am pretty sure it is compensating for the boundary in some way or another.

Someone can feel free to do some real world tests or link to such tests results if it's already been done to remove any doubt on the prediction but running into Mapp is significantly cheaper and less time consuming.

You can also very happily reproduce those results yourself, you can register for Mapp and check things out yourself.

The Mapp prediction does seem to support the theory that whether the sub half space doesn't matter unless both the listener and the speaker is in free field conditions.
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Jean-Pierre Coetzee

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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #17 on: July 15, 2018, 01:08:19 pm »

Did some more measurements in Mapp to check some stuff. Conditions this time the mic was tested 10 meters in the air and 70 meters from the sub, then place the mic on the floor and repeated. With the floor being a rigid boundary again.

Note:

The reason I am using such a long distance is to negate the effect of the inverse square law. It is obvious that the sound level between flow and on the ground will be very different 1 meter from the sub.
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Jean-Pierre Coetzee

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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #18 on: July 15, 2018, 01:08:55 pm »

More pics
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Dave Batistig

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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #19 on: July 16, 2018, 08:04:17 am »

More pics

My application would be a single HDL-18AS flown at the top of the array, per side,  in an attempt to deliver more low end to the top part of the amphitheater, with my full compliment of 8 SUB 8006 dual 18" subs deployed at ground level across the front of the stage. The biggest drawback I see is this would effectively lower the trim height of my top array box by the height of the sub. As it is now, my lifts are 21 ft max. The actual height of the top box is about 19.5 ft, which for this particular amphitheater works perfectly for delivering sound to the street level, where there is typically a large crowd gathered when the amphitheater itself is full.

Even being an RCF dealer, my cost on the HDL-18AS is still significant. I am not convinced that the ROI on this investment is worth it.
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Re: Flown subs...pros/cons? worth the extra effort?
« Reply #19 on: July 16, 2018, 08:04:17 am »


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