subwoofer arc This is a topic that many people are looking for. bluevelvetrestaurant.com is a channel providing useful information about learning, life, digital marketing and online courses …. it will help you have an overview and solid multi-faceted knowledge . Today, bluevelvetrestaurant.com would like to introduce to you Dave Rat s End-Fire Adjustable Arc Subwoofer Array. Following along are instructions in the video below:
“Design all right so how do you build dave rats. Adjustable in fire arc. Subwoofer subwoofer array. So that s what i m going to talk about in today s and how i deconstructed it and i m also gonna talk about my birthday.
Today is my birthday. My dad sent me an electric yodeling pickle. So if you want to hear what that sounds like you have to wait till the end of this video. So when i did the interview with dave he was talking about this and i was trying to picture it but i was like number one you usually don t do an in fire.
Array with only two elements and number two i ve never heard of combining an arc with an in fire just sounded. Really weird. So i had to do a lot of work in map. X.
T. To try and figure out what he was talking about here s the article. I just did this design in sketchup. So you could kind of see what it would look like because what we re gonna be looking at today in map.
Xt are all two dimensional designs like this it s sort of hard to imagine so keep this picture in mind as we re going through this so where did i start. I started in merlin ven. Ven s subwoofer. A ray designer just to get some of my first numbers.
Some restrictions some limitations for the. Design so i started with an entire. Array i started with 19 meter spacing which i had already defined in the article here and that s basically just quarter wavelength of this 45 hertz. Which is the number that dave specified in his design.
So he wanted a null at 45 hertz and then back of the array great. So that s what we have you can see it in the prediction down here. And it says right here first cancel 45 hertz. I wanted to go through these steps.
Though to see where the preferred filters okay. 30. And 60 hertz. So i ll go ahead and put those in now.
I ll move on to the physical horizontal array. Which is here so one of the things that dave talked about was making the speakers go wider out in the arc for a wider. Coverage and closer in for a narrow coverage and i m not very experienced with arc arrays..
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So i was like okay how far can those go apart. Well. I know it should be 2 3 wavelength for maximum distance from each other. But i don t know how exactly that s gonna work out so i wanted to look at that here in the calculator and so what i did down here in the bottom.
I m sorry this doesn t really all fit on the screen as i m basically looking at these polar plots. I m gonna turn up the distance between the subwoofers until the pattern starts to fall apart and that s what i know okay that s the maximum distance. So i could just start putting numbers in here let me set this back to 0. I could just start putting numbers in here in the spacing until i find that and that is one way that i did it.
But i could also look at 2 3. Wavelength and 1 3. Wavelength. So let s talk about that.
So. What i want is the first the wavelength of 60 hertz. Because that s where the top of my range is here so if i look at this guy pretty much its operational range is going to be from 30 to 60 hertz okay. And okay so i get that wavelength and then i multiply that by two thirds and that gives me this 125.
Number now that s in feet. So. We ll divide by three point two a one to get three point eight feet sorry meters and i first i put that number in and i thought great but then i look down here at these polar plots and i was like oh wait. This is a little bit too much i want something a little bit cleaner because i don t know exactly how this is gonna work out with the in fire combination so let me start out with something clean.
That doesn t have any of this these side lobes coming off of there so although two thirds wavelength is probably the maximum there i don t want any of this stuff happening. So let s go with one third wavelength. So let s go back over to my calculator here. I wish i could just go back in time maybe i can oh yeah okay cool.
I never noticed this before can i just click on this yeah. It s cool and can i click here sort of one third six point two eight seven divided by three point two eight one. 191 meters 191. Okay and this looks better down here right so these polar patterns.
I m looking at here at 29 45. 50. And 60 and they all look really good they actually look a little bit too good. What s going on here.
Oh. That s cause. I only have two of them okay..
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I m actually supposed to have three of them there. We go okay. So this is one of the one to look at is that this my highest number here. 60 hertz is this one right here and it does do this figure eight pattern.
But it doesn t start to have these side lobes that i didn t want the next thing. I did is basically just start increasing this arc angle. Until these numbers down here the opening angle were no longer usable and basically for me if it goes up to 360 degrees. Then don t have any really any control anymore so i wanted to see how far i could go with this and you know i started with something like 20 and sorry.
I have to keep jumping around this monitor is kind of small so i m looking at the number 45 hertz here so i can actually do these turn these off yet since i m really focusing on 45 hertz with this whole thing then i was really just looking at that number for the opening angle. Yeah cuz. 29. Hertz is already at 360 degrees.
So i m not going to really worry about that. But i will look at 45 hertz and i basically brought this up as high as i could you can see that this arc angle is getting bigger and over here. I m up to 144 degrees just pretty high 120 gives me an opening angle 160 degrees 176 so i think this is the end of it okay 176 once it gets to 180. Then it s just going to flip to 360.
Okay so there goes the 360 so 125 degrees was the maximum angle. That i wanted to use there. So that s how i did these initial designs and then i think i just went down here and clicked export to map online pro. This is where i ve got my in fire array these two guys and then the arc array all combined this was my first attempt and if we look at the whole thing.
And don t want to look at the rear yells hook up the rear. What i found in my first attempt here looking at this microphone in the rear is that i have a null here. At 51 hertz and that s not where i wanted i wanted it 45 hertz down here. So i know what s the problem.
I had to play around with it and look around for a little while but i finally discovered that this guy this guy then yes. That s six point two eight feet offset. Which is what i want for the in fire array. But when i rotated these side speakers in the arc.
All the way around now there this one s a lot closer to something like three feet closer. So this is and there s two of these so in terms of average phase. They really start to pool the whole thing. And that s why.
The null ended up being up here. So. I said okay let me redesign this so let s open up version..
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Two. And how did i figure this out so. I drew this triangle here. So i could show you my work and here s the deal so i want the distance between these two lines here and let me draw.
These so you can see them better. I want the distance between this line in this line to be six point two eight feet. But how do i figure that out with just like moving them around over and over and over again. So i opened up a triangle solver.
Here. And if you just type in right angled triangle calculator in google you ll get this thing. And if i solve for b. Which is not this line here.
But if you draw another line that goes all the way back to right under here. Okay now we have this triangle. So if i cut this see this triangle that s what s going on here. And when i put in all of my dimensions.
Then i figured out that hey this be number here needs to be a hundred and eleven point sixteen feet. And that is how then i got the position for this and then i just changed these other subwoofers relative to that position so i m not going into a lot of detail there so let me know if you want more information about that. But i use that triangle solver to figure out how far how much farther forward. These subwoofers needed to go so.
That the offset between the rear sub and these side subs is six point two eight feet and not this guy here okay. And that moved my null down here closer to 45. Which is where i wanted it and let me show you how i is because this is the same way that you would do it in the field. So i solo this speaker up i ll take my front measurement.
Microphone store. That then i will take all of these guys together and make sure that average together that they line up here in the phase. Right so that then when everybody plays together we got summation through their operating range. So this blue guy here in a summation and then i could just take a look in the rear.
And see where is that cancel at and there it is the only other optimization thing that i didn t touch on yet is the level setting. So i think i did the level setting in the rear since that s where i wanted to optimize the cancellation. So measuring the rear sub. This time from the rear and store that then measure the front subs this time looking at the love is where i got that level off set that you see here about 8 db because when these arrive 180 degrees out of phase in the rear over here at 45 hertz i want them to arrive at the same level as well so matching level not matching phase is how you create cancellation.
So why are we doing all of this. So what dave talked about is that he s trying to limit the amount of interaction in the middle. So let s take a look at an example of that so i have one called stereo..
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So imagine that maybe you have some kind of audience playing here and let me just start with two these two guys in the rear. So this would this is going to do a prediction of your normal left right stack right so we ve got summation down the middle and then we ve got cancellations here and then we ve got this cancellation that goes like this if we use this array instead you can see that i sort of have them aimed out at 45 degrees. And we take a look at not only have we ve gotten rid of a lot of information back here in case. There s you know some other show going on back here and also in case.
We have you know a stage here and we want to get some low frequency energy off the stage. We ve reduced the interaction here in the middle a little bit so if i get rid of these you can see you know i think i have here we go so now we can have a kind of a side by side comparison. So here s the old one on the right and here s the new one on the left. And you know if we take a look at where this audience might be you can see the reduced interaction.
So this valley. Here isn t quite as bad you can see it fills in here. A little bit and over here on the left. Where i drew this little triangle.
It s widened out a little bit now the last part of the article as me sort of wondering to myself what if i took this same design and flipped it around to be a gradient because to me it makes more sense that if you have two elements. It would be a gradient and not an in fire. So here s what that design looks like it actually looks exactly the same all i did was change the processing. So here now the delay has moved from this channel this channel and then i reversed the rear sub and initially when i hit predict it looks almost exactly the same the real difference is when we take a look at the measurement.
Here we now have broadband cancellation here compared to like that knoll around 45 hertz that we had with the previous design. The other thing is that there s a null here let me get rid of some of these we do have this knoll that s happening here. But keep in mind that these are horizontal lines are 10 db. Apart.
So if this is 90 up. Here. Then this is 80 70. So so we re already down 20 db.
By the time we get to the snow shouldn t be that much of a problem. If we re running a linear system. Now. I guess if we have like a huge boost and ourselves we re turning our subs you know way up then this might be another design consideration.
But i didn t really go much beyond that i just wanted to see what the difference would be if i flipped that around and made it a gradient. I ve never tried this in the field. I was just playing with it in map xt because i wanted to see how dave had done this to try and deconstruct. It if you guys have used this in the field.
Please let me know i d love to know what your results are and now you ve all been waiting for the electronic yodeling pickle sound design. ” ..
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