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This is kind of what I thought you might be thinking of doing and is why I wanted to get your attention regarding it. Yes, sub-low frequencies are omni directional, but that's exactly why putting them back to back could cause you issues. With the subs facing away from each other, the will be "out of phase" with each other. Meaning that the crest of the waves will not be in sync with the waves of the other. The result is phase cancellation and comb filtering along with a very odd dispersion pattern.

The other issue with doing this is that as you start to put subs together (or any other speakers for that matter) they start to become more directional in nature as a result of cancellation and coupling. There's a lot of complexity in what you're attempting to do and I fear you may find more problems than you're anticipating. There's far more to be considered than what I can realistically discuss here. I'd recommend reading up on the subject, especially if you start running into strange behaviors.

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DJ Tony
Let It Rip Karaoke

I often see big powered subs setting side by side with each other.. in fact, EVERY time i've seen multiple subs they've been sitting side by side.

Why couldn't the dude just set them in there side by side?

On a related note.. most of the car shows i've been to are more social events.. emphasis is mainly on the cars, and people discussing their cars. Any music playing is largely for background noise or to set the tone (50's music playing for instance)

Seems like a heck of a lot of sound system. Only real need I could see for subs would be if they had a dance type area set up.

What size events are you planning to target? Clearly not the local A&W Rootbeer stand or Sonic, right?

Actually, yes, thats part of exactly what type of event I will be doing. But mostly I am looking for shows set up in parks and large areas like big parking lots.

Thanks for realizing that the sound itself isn't as important as just having sound. Not too huge of an issue if the sound isn't top notch high quality sound you would expect to find at things like concerts or public performances. Car shows only need background music and vocal announcing is all. But this type of set up should be able to give decent quality sound for such an event.

Tony, I have done a little research into comb filtering, and if my math is correct the speakers on top will have no problems with that at all. The subs however "might" have such an issue, but then again, they won't be pushed to the point of needing to be "thumping" to the audience. Just enough to give some depth to the sound is all. However, if I ever need to do dances at parks or pavilions, then yes, i might have to reconsider the direction of the subs AND the array as well. That is one thing I will have to contend with when the time comes.

The array speaker set up is designed for it being able to be tilted downwards as much as I like and also can be rotated in any direction. I can also use as many or as few speakers as needed.

Wow,

Just wanted to know if it is available now?
Are you going to sell it?
hahaha....
I wanna buy...
How much that cost?

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Nope, its alllll for me!! hehe

I have some work to do on it still of course, but when it's done, I'm hoping it is gonna make me a lot of money! Woot woot!

Normally in a club or other setting where the entire audience is in front of the sub woofers and usually pretty close to the middle of the stage (where hopefully the subs are) it can actually have a desired affect.

Putting two subs side by side like that makes them directional. You end up with what folks refer to as a "power alley" where down the middle straight out from the subs, phase coupling causes an area of significantly increased sub-low performance. The problem is when you off to the side of that alley, phase cancellation results in serious dead spots where the sub-low frequencies drop off considerably.

In Mr. Scott's case, he needs to project audio in an omni-directional pattern. Putting multiple subs side by side will actually reduce the omni-directional nature of the sub-low frequencies. Putting them back to back could result in even worse phase cancellation. In other words severely reduced performance and other phase interference issues.

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DJ Tony
Let It Rip Karaoke

Tony, could you give me your recommendation on sub placement then? It would be greatly appreciated.

Well unfortunately getting a great design for this often requires the use of delays and is largely dependent on the design of your subs. However, my suggestion would be as follows, and this borrows from something that was used in Metallica's "World Magnetic Tour". Now granted they did it with 4 vertical subwoofer arrays, but doing what I can of the design work in my head (I don't have access to acoustic prediction software at the moment so I can't test this) it should work well even on a smaller scale with 4 single subs.

Basically the 4 subs get arranged in a quasi-star pattern with one sub facing each of the 4 compass directions (don't have to actually be true to the compass directions but basically need to be 90 degrees from each other). It should look like the attached image.

The big key here is the size of your subwoofers though. The overall width of this little sub woofer cube (measured from the center of each speaker cone) needs to be less than 9 feet (assuming a crossover point of 120Hz, can be longer if your cross-over at a lower frequency). Basically the max dimension of the "cube" needs to be less than the shortest wavelength they will be producing (wavelength of 120Hz is 9.4ft at sea level at 72 degrees). The other constraint is that the drivers in each sub need to be within about 3 1/2 feet of eachother (1/3 the shortest wavelength). So again you can increase this dimension by lowering the cross-over point.

Trying to get subwoofer coverage in "the round" as they say, is probably one of the toughest assignments. This "sub cube" design is pretty recent in terms of design. I don't believe any phase/polarity changes need to be made and I'm confident that no delays are required as there is no beam shaping going on here. Also this works a lot better if you have single speaker subs. It would work with a dual, but would be more challenging.

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DJ Tony
Let It Rip Karaoke

Tony, I see what they are doing there, seems like perfect sense... How about with just 2? That's where I will be starting. Only will add the other 2 if I deem them necessary, and at a later date as well. I did set this equipment up once in my front yard, with the subs both sitting together and pointing in the same direction, (same way i do it at my clubs) and it worked just fine. However, it wasn't set up the way I will be doing it at car shows/outdoor events. In my front yard, it was all pointing in one direction, straight forward with satellite speakers pointing slightly inward. The sound was actually pretty amazing!! I found I had more power than I thought I had. I'm actually pretty excited about the 360 degree array set up. It should be very functional and with pretty good sound as well. I know you teckies and sound men will not think I'm doing the correct thing, but I have already picked out my six speakers. I will be using the Behringer B212 XL's... for their weight (24 pounds each), and also their sound,, not to mention the price is good ( I can get them for around 125 each.)

Each part of the system has it's own amp and controls. The array will be ran off the monitor output with its own amp and eq. The satellite speakers will be run using the main outputs and its own eq. The subs of course already have their own amp and ran through a crossover built into the main eq. with its own sub outs.

I wlll be replacing my current board (Behringer Xenyx 1832FX) with a newer model of the same board, but with the build in compression and USB. I can get this board for about 220. I was also looking at the Yamaha MG124CX, but when I actually saw the unit itself in person, I talked myself out of it. It isn't what I was expecting for sure. However, the Yamaha MG166 might be an option too. The MG124CX is not well constructed , only a plastic housing with limited options for mounting. And doesn't have the same features of the newer Behringer Xenyx 1832FX USB board, which I am looking for.

In the future I will be replacing my (3) Behringer EP2500 amps with (3) Carvin DCM 3800L amps... as soon as finances allow. I will be keeping the Behringers for whatever I might need, such as adding the extra subs, or just for backup.

Thanks again Tony for your input and insight,, it's very much appreciated.

If you need to use only two, there are two ways that would work best. First would be just to put them side by side facing the same way and just deal with the changes in directivity that will result. The amount of this affect that is realized will depend largely on what size drivers you have in your subs (larger speakers are inherently more directional than smaller ones).

The second way to do it would be to place them side by side facing in opposite directions (180 degrees to each other) with the drivers line up horizontally. The one trick here is that the subs should then be sent signal that is phase inverted from each other. Many powered subs have a phase switch that will accomplish this. If your subs don't have this switch or are passive subs, the next best option is to reverse pins 2 and 3 on the XLR going to the amplifier (reverse tip and ring if you're using 1/4" TRS). If neither of these is possible and you're using passive subs, you can also wire it to the amp in reverse polarity (i.e. positive terminal of amp to negative input of speaker and vice versa), however this is my least favorite of the options.

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DJ Tony
Let It Rip Karaoke

To let you know, I do have passive subs. They will be used for my karaoke shows as well as these car shows, so changing polarity isn't a good idea. However, could I make "one only" short speakon cord with the wiring reversed on this short cord only? And use it when I am doing a 2 sub configuration at outdoor events? (hence your suggestion of a 180 degree opposite side to side layout) Is this good?

That'd work, like I said, not my favorite way to do it, but it does work.

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DJ Tony
Let It Rip Karaoke

You know, I was thinking more about this tonight while on the road. Originally I dismissed the idea because I didn't think you'd have the room, however looking at the pics now, depending on your subs you might. If you can stack the two subs one on top of the other facing the same direction, that would probably be the best solution.

Just as subs placed side by side become directional on the horizontal plane but remain fairly omni-directional vertically, the exact opposite is true when they are stacked vertically. That might be your easiest answer for this application.

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DJ Tony
Let It Rip Karaoke

Thanks Tony for not just passing this by. I very much appreciate all your input. When I actually get things set up, I probably will try several different options for layout, just to find the right mix. Nothing is set in stone here.

To everyone out there, I'm all ears on your input on this whole entire set-up, what do ya think? any ideas? how about outdoor lighting? foreseeable problems?

Thanks in advance ya'll. Peace out!

Scott

Pretty neat looking setting up Mr Scott! You'll have to keep us informed on how it works for you. I'm sure more of us could benefit by this type of set up for outside activities.

In reading the back and forth on the subs, though! I wonder how far a reach you will actually get from them. I'm sure it's dependent on a lot of variables. Would you really get enough out of the subs to benefit the entire playing field of the card show? Since you are using for PA announcements and background, would it be significant enough to justify the cost?

I like the idea, but not quite sure of the result. Let us know how it works out!

You might also consider selling advertising space on your rig to help defray the costs of providing such a set-up. Local businesses will pay a good fee to get their name out there.

Good Luck!

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I have given some thought to the advertising space too. I think it's a good idea, just need to see how that plays out.

As far as the sub thing goes, yeah, I think it would be a big benefit for the overall sound... sub - sounds actually travel a long way, but just not the "thump",, I really am not after the thump as I am just a proper balance.

I really would like some more input on everything,, would be great if I could keep this going.

So do any of you fine folks have anymore input on this idea? How about lights for outdoor events (think, 'at the park'), or possible issues that might arise? I would very much like more points of view on here, there might be something that someone else might think of that I am overlooking. So, please feel free to offer suggestions or ideas or just comments period.

Thank you all
Scott

Well how about an equipment list of what you'll be hanging off this rigging? You said six full-range speakers on the top rack, what speakers? What subs will you be using? What amps are you driving those with? How big is the overall venue? Honestly without that information, any further discussion is largely irrelevant.

As far as lighting, what kind of lighting are you talking about? What do you need to cover? I'd love to keep discussing but we need more details from you.

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DJ Tony
Let It Rip Karaoke