Building corner structures for outdoor subwoofers.

[SunGazer]

So this may or may not have been covered on this forum somewhere. However I am having little luck in my search for answers. Here;s too hoping someone can shed some light for me.

So as I model designs and output in hornresp I noticed that corner loading a subwoofer results is nearly a doubling of output! Nothing new there, I knew that.

However, this has me curious. I'm going to be providing sound for some outdoor events & I was curious to know just how solid of a corner structure I would need to build to gain as much SPL as my simulations are spitting out?

Being as most interior walls are simply 2x4 studs with dry wall on each side can I get away with building "portable" walls from 2x4's & two sheets of plywood on each side as long as they cover the size of the subwoofers and then some?

To be clear, I want to drag my Tuba HTs out but I really want to impress the crowd and these pretty much NEED to be corner loaded for any good effect.

I mean I guess I could just try it, measure the before & after and report back but I was hoping for some knowledge before I start.

Anyone done anything of the sort??

-Josh

 

[chris661]

There's not that much pressure being applied to the walls, so you could probably get away with propping up a few 4x8' sheets of 12-18mm wood.

With all the extra stuff to transport, though, you might as well have more subs.

I think the walls will have to be very large, though.

Chris

 

[turbodawg]

I built a collapsible barn door / horn extension to put on my pair of 15" BR PA subs for outdoor use. The mouth is about 80"x40" and it's about two feet deep. It boosts response in the kick drum range, and improves sub coupling across the whole range. Took one sheet of plywood, misc wood, and some hinges.

I've actually got one of those little JBL Bluetooth speakers, I had it out on somebody's deck for a small party, and put it directly on the floor with a couple of shovels behind it to reflect the bass - this actually worked.

I'd say you should build up some horn extensions for outdoor use, similar to the Levan horn extension. This should not be too hard to model in Hornresp. You might even be able to contact Bill F and might be interested in helping you with it. Otherwise with enough info someone here could help you model it.

An externally hosted image should be here but it was not working when we last tested it.

Also check out these links:

levanplan.jpg Photo by NoMeRcY82 | Photobucket
http://www.diyaudio.com/forums/pa-systems/261490-sub-horn-extensions-barn-door-question.html
Wave Guide for 186 - Speakerplans.com Forums - Page 1

 

[turbodawg]

Oh yeah, in a PA system, I assume you're using these with some sort of time alignment, either physical or electronic?

 

[SunGazer]

There's not that much pressure being applied to the walls, so you could probably get away with propping up a few 4x8' sheets of 12-18mm wood.

With all the extra stuff to transport, though, you might as well have more subs.

I think the walls will have to be very large, though.

Chris

hey chis,

Considering that I can effectively gain the same SPL increase as doubling the # of cabinets (gets expensive when you are thinking in multiples of 8) and that I can design a fairly easily structure which the sub can sit on during transport I'm not overly concerned with moving a few more things around. I mean I'm thinking 4 sheets worth of plywood cut up and predrilled/fitted, maybe a dozen 2x4s and a cordless drill. Add 30 minutes of time to erect and the gains could be substantial for a relatively low input of time & money.

I built a collapsible barn door / horn extension to put on my pair of 15" BR PA subs for outdoor use. The mouth is about 80"x40" and it's about two feet deep. It boosts response in the kick drum range, and improves sub coupling across the whole range. Took one sheet of plywood, misc wood, and some hinges.

I've actually got one of those little JBL Bluetooth speakers, I had it out on somebody's deck for a small party, and put it directly on the floor with a couple of shovels behind it to reflect the bass - this actually worked.

I'd say you should build up some horn extensions for outdoor use, similar to the Levan horn extension. This should not be too hard to model in Hornresp. You might even be able to contact Bill F and might be interested in helping you with it. Otherwise with enough info someone here could help you model it.

An externally hosted image should be here but it was not working when we last tested it.

Also check out these links:

levanplan.jpg Photo by NoMeRcY82 | Photobucket
http://www.diyaudio.com/forums/pa-systems/261490-sub-horn-extensions-barn-door-question.html
Wave Guide for 186 - Speakerplans.com Forums - Page 1

I've seen some of that information of horn coupling. I've been running some models on horn resp & due to the somewhat low flare rate of the TUBA HT most of my sims show 3db gains above 60hz, playing with the flare rate and length yields similar results.

Since the Tubas perform SO much better when fired into a wall I am going to adopt that strategy into my structure be firing the horns perpendicularly from listening axis into a 8ft corner. Whether that makes the corner a corner or a horn extension, I'm not sure??

Oh yeah, in a PA system, I assume you're using these with some sort of time alignment, either physical or electronic?

Ill be using a driverack 260 for time alignment, EQ, x-over, high pass etc.

Tomorrow I am going to see what I can do, drag my stuff into a warehouse space & fire it up. Expect pictures and measurements!




-josh

 

[Greebster]

Sure you can build large walls, they'll be quite heavy and pray there is low wind conditions.
I'd suggest cardioid subwoofers built out of PVC tubes, but I'm weird like that.

 

[carneoleon]

i once tested a simple 4 by 8 piece of 18mm ply screwed to the front of 2 300liter external 2x12flhs... i gained approximately 3dB across all frequencys... I'm on the wrong laptop, otherwise I could show the pictures and measurements!

If you really want to impress, and you apparently can't do it with your current setup, build more, V-load them, stack 'm high, add 2 barndoors and that should impress

 

[turbodawg]

Since the Tubas perform SO much better when fired into a wall I am going to adopt that strategy into my structure be firing the horns perpendicularly from listening axis into a 8ft corner. Whether that makes the corner a corner or a horn extension, I'm not sure??

I'd say it makes it a horn. If you measure response at 1m, within the corner structure, you'll get the expected corner loading. But if you measure at 10m, you'll get something else entirely, as if you put an arbitrarily shaped horn in front of your speaker.....which is exactly what you are doing. That wall is going to need to be very beefy to avoid vibrating like crazy.

Look very hard at making a proper horn extension, it's the way to go.

https://www.freespeakerplans.com/fo...er-loading-horn-extensions-cardioid-placement

Quad 18's on a big horn, "When bolted directly to the front of two Infra-bass, the waveguide increases the output of the pair by up to 10dB at 33Hz."

Funktion-One | Products | Infrahorn

http://forum.speakerplans.com/infrabass_topic12677_page5.html