Oct 17, 2012 04:51 pm On the ground in front of the stage is my immediate thought without seeing the whole picture, but I am betting sound man extraordinaire Rob Stemple has some thoughts.
Subs Placement
Posted on Oct 17, 2012 04:18 pm
mclir9
www.witchsmark.com
Member Since: Aug 13, 2006
I have (2) Yamaha 18" Subs and we are going to playing a show with a stage that is approximately 25' Wide, 12' Deep and 2' High. The stage is solid, meaning it actually has a front and sides covered with wood and carpet. Where would be the best place to put the subs for that chest pounding kick drum sound??
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Oct 17, 2012 04:51 pm On the ground in front of the stage is my immediate thought without seeing the whole picture, but I am betting sound man extraordinaire Rob Stemple has some thoughts.
Oct 18, 2012 08:33 am Thanks dB, I also got a tip about placing them side by side right next to each other which gives you an extra 6spl... what do you think of this??
Oct 18, 2012 10:42 pm An extra 3 dB with them side by side. You get 6 if you double the amount of subs. In other words 4 subs in total.
I don't know enough about your subs to give you the best placement for them, as some Yamaha subs are very omni directional. So, sometimes putting them side by side, you get this standing wave. And what happens with that, is that you will walk the stage, and hear a spot of heavy bass, and two steps away, you nothing. Should this be the case, separate the subs to be under each of the high packs that you have. You'll lose the 3 dB extra you get with them side by side. However, you gain even coverage.
So, the best thing to do is to experiment with them some to see where the sweet spot will be.
Oct 19, 2012 11:04 am Rob, perhaps you can shed some light on this...Paully, in his club, did something with the subs hidden under the stage, built an array of them, front to back, spaced apart so as to have the next one start where the wave from the previous fully completes a form...and he has something like four of them lined up...and I have to say, his club has the biggest, tightest bass sound of any club I can remember.
Any thoughts on that? I currently have two subs in my basement, so, well, you know what I am thinking...LOL
Oct 20, 2012 03:51 am Anytime that you can have more than two subs, you can array them. However, it does require separate processing for each zone.
How this works, is using the subs natural resident frequency to set up the timing of the subs. I know. What?????
In all of the literature that comes with your speakers, you will find a frequency chart. On this chart, they will list the resident frequency of your box. If they don't list it directly, they should have a chart that shows a bell curve of all of the test frequencies that were used. The highest peak on that chart will be the resident. And resident is a term used to describe where all of the harmonics of the box come together at. And so it naturally has a stronger response with that frequency.
Once the resident frequency is found, you need to turn that measurement into a distance. For this, you can use an easy program by RealTraps. There Frequency Distance finder program is a free download, and will tell you how much room you want in between your subs. Now, there is a ton of different theories on how to accomplish this. For me, I prefer the quarter wave placement. Which means that you plug in the resident frequency into the RealTraps program. Then you look for where the 1/4 wave distance turns out to be. Lets say you find the 60hz is the resident of your box. Plug 60hz into the program, and hit Calculate. And it will give you a 1/4 distance of 4' 8.5".
The 4' 8.5" will be the distance that all of your subs will be separated by. And I would start in the middle of your stage for your distance. So, 2' 4.1/4" from the middle should be where the first two subs should start. And then the next two at 4' 8.5" for the next.
Now, once you have the distance set up for your subs, you now need to delay the subs into zones. For only four subs, you only need two zones. As the idea here is to put the subs in an electronic "U". Which will widen the front wave, and decrease it behind the subs.
For putting the subs in a electronic U, I have put the outer subs behind one full wavelength. So, using our example of 60hz,
I'll finish this tomorrow. Sorry, I have somethings that I'm dealing with right now.
Oct 20, 2012 02:46 pm As I was saying.......
Putting the subs in an electronic U. I do prefer having the outer subs behind one full wave length. You can experiment with your subs with different timing. I have just found that one full length will make the coverage extremely wide, and tight sounding. So, with our example of 60hz, we will find that the outer delay will be 18' 30" behind the middle pair.
THE THING THAT IS CRUSTAL is that all of the subs MUST be in the same plane as one another! Any variance will cause a lobe in the wave, and give you a little cancellation.
Now, this is for only 4 subs. There are different equations as the sub number increases. And not all subs are created equal. So some experimentation maybe required to get the desired result. Which is tight, wide, and ever little on stage, but bone crushing out front! :)
Oct 30, 2012 12:53 pm One correction. I was thinking of the last array I did when I mentioned putting the outside pair one full length behind the middle pair.
That would be wrong. My mind was on a still larger array. The outside pair should start at .22 milliseconds behind the middle pair to start the wider angle. And if a wider angle is needed to cover the room, a .33 ms delay can be applied.
Oct 30, 2012 12:55 pm What you describe is pretty much what I was thinking it was, just keeping them distances apart to be working complimentary with the length of the wave, kinda cool...completely impractical for my home theater though...which is where I was thinking about playing with the concept...neat idea though...if I would have thought about that earlier in the project it may have been more likely.
Good info though, thanks a ton!
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