The BEST subwoofer array for large concerts?

sound design so is this the best subwoofer array for large concerts i don't know i'll let you be the judge of that but that's what we're gonna get into in today's video so i recently interviewed adam hill and just doing some research for that interview i discovered that he has a bunch of papers on the aes website about subwoofers and subwoofer arrays and one of those is this guy 7971 subwoofer positioning orientation and calibration for large scale sound reinforcements and in it they discuss many of the challenges related to ground-based subwoofer systems to help have nice even coverage in the audience and less coverage on the stage so rejection on the stage summation in front so what i did in this article is try to recreate the results and understand them a little bit better so the first thing i did over here in map xt is just try to set up the design to be like there so i've got a stage here imagine that this line is like a barricade and i've got audience over here so in the article they go through a bunch of important features about gradient arrays and coverage patterns but we are going to skip down to this section called optimal subwoofer setup uh so they describe where the stage is and then the first thing they suggest is four single cardioid subwoofers across the front of the stage four meter spacing so let's do that map xt i've already i already have those set up but let me show you how i built those so if you're still using a 2d environment because you haven't started using map 3d yet then this is the way you can do that you just insert a subwoofer and then put another one right on top so if i grab one of these you'll see that they're just right on top of each other and then the way that you optimize an inverting gradient stack is the same way you optimize an inline gradient subwoofer which is in the rear so i have a microphone here and i'm going to solo the forward forward-facing element first okay so here's a measurement of my forward-facing sub at the rear and now i need to select the rear sub and i might have to just move this forward step out of the way for a second okay so now i can select the rear sub and you can see that we have matched level and we are phase aligned but polarity inverted and to prove that to you i can take out the polarity inversion and we can see that now they're level matched and phase match why did i level match them well because i'm trying to create really great rejection at the rear so i'm optimizing for rejection at the rear really close normally with an array like this you could just leave the gain alone and know that you know at distance they would be level match but here i'm trying to create a specific effect which is cancellation really close at the rear there okay so level and phase matched and now i'll put the implaritium version back in okay it looks good and now i need to put this back together and now if i select this guy and zoom out we should see a nice gradient array great so there's one of them by themselves and so now all i did was copy and paste these three times so that we have four across the front let's see what that looks like okay so here we are at 63 hertz and let me show you a couple of other frequencies let's look at 40. and let's look at a hundred and i want to point something out to you at a hundred notice how there's quite a bit more 100 on the stage okay because i'll be showing that to you again later okay so let's go back to 63 and let's continue on so the next thing that the authors point out in the paper is that this is not great yet um the initial setup gives very limited coverage across the audience area although these are no no's okay so they say that the the coverage is not great here but you can easily fix that by extending the line make this line longer add more subwoofers and i'm going to go ahead and skip a step here so we're going to add more subwoofers and this time it'll be a three element gradient array because and i'm going to skip a step because the next step is to then angle those outside subwoofers 45 degrees so here i have those so exact same array i just added one more sub on top and this time when i optimized it i didn't need to turn down the rear sub instead i needed to turn down the tops up because now i have two forward facing subs and one rear facing sub let me show you what that looks like okay so there's our three element inverted gradient stack oh and i forgot to mention that the reason that they suggest making this one taller is that now it won't block sight lines so now it's not in front of the stage so you can add more power here okay so now we have a longer line and even more subs on the end so let's look at that okay and this is the result at 63 hertz let's take a look at 40 hertz and let's take a look at 100 hertz and you can see that it does have the result they wanted which is coverage is now not just this pointy spaceship but has extended across the sides here better is it the best subwoofer array well let's look at the results across more than just one frequency so to save us some time let's just look at these images i made so i compared the first row front of house downstage center and downstage right let me show you where those microphones were so i'm calling this front of house first row downstate center downstage right and you can see that the results are not super impressive we have really nice rejection here in the low end of this subwoofer's operating range but then up here around 100 hertz we really only have like 6.75 db of rejection and now you remember we were looking at 100 hertz and you can now see why i was pointing that out to you is that you know these shorter wavelengths we've got this overlap happening and it's just going all over the stage here in that higher frequency so can this be improved i think you could probably come up with some better ideas i played around with it a little bit the only thing that i tried was adding an extra sub they suggest a maximum spacing but not really a minimum one so i i tried it i tried adding an extra sub so having um five subs across the middle instead of four and also tried adding a high pass filter to see if i could reduce some of that 100 hertz and it didn't really get better okay similar results about the same i think really at this point the best thing i could do is take this whole array and just move it forward a meter and it really should be forward to meter anyway because i'm too close to the stage now this doesn't really matter in the map xt prediction environment because these architectural visual aids these lines here don't really do anything to the prediction they're just there to help our eyeballs but really moving this this way would help get some of that sound off the stage but moving the entire array this way would help get some more of that sound off of the stage now of course that's going to get more of the sound onto the front row here and so it doesn't really change the front to back ratio um but this is the this is really the main thing i can think of right now to improve this so i'd love to know what improvements you would suggest so if you head over to the article and scroll to the bottom you'll see that you can download my map file here if you want to play with it so i'd love to hear your thoughts on it in a future video i'm going to go deeper into this article because they talk they start talking about hey what if you had to do 270 degrees of coverage so instead of just this area in the front here what if you also had to cover over here all the way to the sides they get into another interesting subwoofer array suggestion here i didn't want to make this video even longer but i'd like to talk about that one next time because it's pretty cool sound design

Channel: Nathan Lively

Views: 7,574

Rating: 4.976048 out of 5

Keywords: live sound, sound engineering, subwoofer, cardioid

Id: AWydFTUguzQ

Length: 9min 11sec (551 seconds)

Published: Thu Sep 10 2020