Pt 2 Live Sound Subwoofer configurations

oh my name is Dave brat and I'm gonna talk about one of my favorite subjects well first there's a lot of interest in different subwoofer setups so I thought I'd talk about stuff that works and doesn't work different applications and some of the aspects of subwoofer setups that are generally overlooked conventional stuff setup there will be a you know southern glass selves on the right stage in the middle you know it's just kind of your basic go-to starting point there's some major issues with this setup primarily the admirer map simulation program and these programs has various programs out there that simulate what subs are supposed to do any setups and actually they work quite well but there's some caveats to them as well as you can see what I call the butterfly we have our ally in the middle the two power valleys here would be power alley in the middle the two power valleys just either side and then off to the sides not a whole lot goes on oh let's say you take four subs and put them in a ring a point-source ish type type setup what you have here is go get pretty much a hemispherical coverage whatever dealing with subs one real good way to think of it is equidistant wherever you're equidistant from the most amount of subs is where they'll be the loudest with two sets of subs you'd be if this one's on you have a power a lead on this point another down here you turn them both on then you get a new one down the middle and the power values are caused by it's the area where they're close to the same volume but you're off-center if people started to increase coverage as he taken start to point these outward now these primary summation points are off to the side you've widened your power Ally you reduced your power Valerie's one of the issues with that is your stage being here now you've started to push the barricade out disconnect the performers from the audience another common setup is setting subs up across the front of the stage this is interesting because it eliminates your to null points because now you have a common center point your power is still there and it will fade as it gets to the side you still have your issues off to the side and if you look your coverage point you now have pretty much a part of a wheel your coverage point vertically goes up you still have significant energy hitting the ceiling and significant energy hitting the band change these two cardioid subs you reduce that your vertical stay is quite good less hitting the ceiling but you still got major issues to decide your width is not that wide take it to the next set we start to look at forming an arc an arc is an interesting setup because now you increased the width of your coverage out front you don't have your power valleys if it's continuous but look at your focal point where are you equidistant you're equidistant from the sub probably somewhere right on stage or behind stage you now have the summation point where all the subs hit you at the same time this is a significant issue like the ring pointed up this arc has a primary focal point behind it and it's coverage gets wider as it comes out and comes back in narrow your significant amount of energy hitting the ceiling again blessed is less than desirable using cardioid subs again you can bring it in but now we go back to the other problem again we have the issue of pushing the barricade out now you've got the band disconnected from the audience in this big dead space here between the band and the audience and you still have it resolved this still doesn't solve your coverage off to the sides improved but not solved to deal with one of those aspects is to do a delayed arc to create a virtual arc of subs where you set them up in a line let's say we use cardioid subs to reduce coverage behind you have these zero these slightly delay these delayed more and he's delayed more than that this one with wide new coverage it solves the barricade distance problem so let's take a look at comparing mechanically art subs with electronically ourselves and I'm gonna start by going back to the pointing source with a point source for a single area where all cells are putting out sounded that at the exact same time no time delay no phase alteration this puts out a uniform circular hemispherical waveform it comes out in all directions when you do an arc and everything is at zero time it puts out this nice curved waveform eats up when this speaker is moving out the one next to it is also moving out at exactly the same time and they're all working together in unison with a delayed arc it's a little bit different so physically they're in the same plane the center cells put out the sound first these put out sound a little later these later and these later than that so from this perspective here these cells are closer to you and incrementally farther away another interesting aspect of this is let's look at it which is four so it's got the virtual sound of that if you go up above it it's got the virtual sound of that where the ones in the center are closer to you the ones that are on the sides are farther away when you go behind it it's got the sound of that again no matter where you go the center ones are closer to you electronically closer to you than the rest a little test rate set up to show you some of side effects now I'm going to set this up in a mechanical but this would be the delay dark you won't save it these two at zero time these two or two milliseconds these are four and these are at six now with their actual delay dark it would be slightly different um here's my setup I've got a laptop that is acting as my sound source and I have that going into a one-in-four out delay I've got a towel wrapped around it comes noisy and out of that the four channels go into this ancient mixer here I like to use old gear I like to demonstrate on the most simplest equipment possible to show you that you can do this at home I've got a tone coming into it right now that is forty six cycles point seven eight can use fifty and that's zero time we can see it on the scope that's it plus two milliseconds plus four plus six as you can see they all sound the same and you should be able to hear that they all sound identical and those are run into this currently just this speaker now I'm going to bring up two at the same time and three my boards old so one and the tonality doesn't change now keep in mind that these are all set at different times and I can show you that as well we can send these over here and take a look at both waveforms so here we can see zero milliseconds plus two plus four plus six and regardless of which ones I bring up the tonality doesn't change the fact that the sideway sounds the same regardless of what we're doing is very important because that is primarily how most of the prediction software determines what your sub coverage is it looks at what a sine wave would do in that environment but if you take something other than a sine wave and for this I'm going to use a kick drum and this is cool to freesound.org and sound a kick drum sound it's these speakers don't do it all up there's unweight format and you should be able to hear that and get a good idea of the tonality of it yeah put them all in the same speaker and as you can see they all sound the same now here's where it gets interesting that the output of this center subs of these center subs will combine acoustically with the output of these subs which will combine acoustically with the next ones over and so on the fact that their waveforms in the open air and acoustically couples so well and or interact so well allows them to be steered that's what we depend on in order for a delayed arc to work if they didn't interact well the delayed arc wouldn't so what I'm doing is I'm going to electronically sum these outputs instead of acoustically now I electronically sum them with the assignment watch what happens when I electronically send up the kick drum sounds to the sine wave and listen I'll try and keep the weight without the same ok so there's all four so basically if you were out here in front somewhere in the summation pattern these for delayed subs that were electronically delete delay to make the shape that's the sound you would hear but listen to that compared to the original signal that should transfer over even to the crappy mic for that camera and it was a pop-pop-pop-pop kind of a punchy it had some uh some of the upper frequencies of the sub range involved and as I added more and more of these electronically delayed subs it became deeper and less dynamic sounding it kind of goes pro um that characteristic I mean it's easy to test you set yourselves up in a line you start hitting put you started putting the delays and all of a sudden all that punch is gone away you don't notice it with pink noise but with a pop or a test or some sort of asymmetrical signal similar to a kick drum it becomes readily apparent the interesting thing is it it's not taken into account prediction software this is though the whole idea that delay arcing completely alters the sound and the dynamics of the low-end now you may have thought of it to be able to actually recreate this and show it was took some thought but I'm pretty excited you

Channel: Dave Rat

Views: 69,830

Rating: 4.9230771 out of 5

Keywords: Dave, Rat, Sound, Subwoofer, Roadies, in, the, midst, cardioid, sub, PA, system, subs, systems, array

Id: B-3pURYOwfw

Length: 12min 48sec (768 seconds)

Published: Sat Nov 20 2010