Mixing Live Sound

Lesson 8 of 17

Loudspeakers

 

Mixing Live Sound

Lesson 8 of 17

Loudspeakers

 

Lesson Info

Loudspeakers

Types of loudspeakers. So before you start working with a console on dh mixing and compression and cue, the important thing to know is, what are you listening to? How are you distributing audio throughout the heir to all the people in the room? This is arguably the most important part of the entire process, because once you get all the power set up before we even start mixing, if you've got crappy speakers or they're not aligned properly or they're not tuned properly, you're going to be fighting them all day long instead of working on the band and making it sound great. S so we should talk about just how you go about tuning loudspeakers and how you go about looking at these and what types there are s o cross offers and passive versus active by amping, we're going to talk about full range speakers, tweeters, subwoofers, three way speakers, lina reyes and then talk about the difference being passive and active speakers let's talk about what a crossover is, so before we get into the diffe...

rent types of speakers, speakers can be ah, a full range speaker, which you'd see like in the guitar cabinet or in like a car stereo speaker, sometimes your typical six by nine car stereo speakers, a full range speaker and those were great, but also crossovers allow you to have crossovers allow you to split the entire signal by frequency to send just the high frequencies to the tweeters send just the mid range two midrange speaker since then just the low into the lower in speakers crossovers basically allow you to go through and set rules or basically set a high pass filter for or a low pass filter for each of those separate signals so you feed the cross over a stereo signal and then the output usually sends multiple outputs for different types of speakers um some car some speakers that air self powered like the mire melodies, for example are was called by amped or triumphed which means that within the actual speaker itself there's multiple amplifiers and each of those amplifiers power each separate type of speaker independently. Those are usually the best type of speakers to work with because each amplifier is then matched to that speaker perfectly and is designed for it on the cross over is built in before the speaker inside before the amplifiers inside the speaker so you just feed it one complete signal and the speaker takes care of the rest. Um if a speaker is not powered, sometimes they still have a three way speaker and you feed it one signal and that's what's called a passive by amp I'm in a passive by emp means that you are a passive crossover I'm sorry a passive crossover basically means that the powered signal is coming in and splitting that passive signal inside after it's already amplified it's not quite as accurate as a active cross over an active crossover that's being fed into a speaker is fee is splitting the signaling a cross over before it's actually hitting the amplifiers, which is a lot more accurate so we're gonna walk through the typical routing and patching for a cross over um and when we get into setting up a front of house mixing this afternoon, we'll walk through some of that but for now, basically understanding what a crossover is and how it used is important um and how they work with different types of speakers. Okay, so the first type of speaker we're going to talk about is a full range speaker like I said full range are usually used in guitar amplifiers, car and home stereos they usually have kind of a limited frequency range you'll end up with like a t hurts to sixteen killer hurts so you don't go all the way down to twenty killer hurts, you know, go all the way up to twenty k twenty thousand hurts, but they do try to cover the entire range the advantage is that they're more affordable they could be paired with sub woofers and tweeters with a crossover s o full range speakers they're sort of like the baseline type of speaker that she'll see um and the design is simple usually have a cone it's made of some sort of paper or cardboard material and then the driver on the other side which pushes the cone back and forth uh next time speaker called tweeters tweeters are typically for high frequency response they range anywhere from twelve k up to twenty two k thing about tweeters that's important is that they usually use much less power they're very sensitive so you usually want a very small power amp to power them the opposite of what a subwoofer would be which obviously has a very high amount of power that's pulling the low end the wavelengths that air created for high frequencies or very, very, very, very small. So the physical movement of the speaker back and forth as much less to move it's, it's it's very minimal movement but very fast movement so it has to be very accurate which is why tweeters are typically designed very differently than a full ranch speaker um the next kinder subwoofers obviously subwoofers are low frequency response you saw the ones that we used there they're very big. You need a giant cone to be able to push that much air because the wavelengths are so much bigger I think a sixty hertz based wave or low anyway the sixty hertz sine wave is like twenty two and a half feet long to make its complete cycle so one sixty hertz sine wave takes twenty two feet from the beginning of the cycle all the way to the end of the wavelength of one cycle so if you think about how much air has to push to create a wave length like that that is physically that long it creates a lot of power it needs a lot of power to push that and also needs a physically very big speaker um for subwoofers, the enclosure is actually super important the speaker itself creates the sound but the enclosure and how that amplifies the signal becomes much more important than a mid range or a tweeter because you're actually pushing all this air out there and how that launches out into into the atmosphere around it is really important um t they go down to twenty hurts all the way up to one hundred eighty hurts depending on where you sent the crossover um and how when we when we walk through setting up for a house, we'll talk about how you patch monitors how you patch subwoofers in and set them up you can either have been fed from the cross over, you can have them fed on inaug send or you can have them fed on a matrix fader which I there's three different ways of doing that um so all these air combined the typical speaker that you'll see is what's called a three range speaker onda three range speaker is the most common type of loudspeaker you'll see in venues and clubs there's three speakers inside, you've got the subway for the mid range and the tweeter all in one enclosure, if it's, a passive speaker than typically the crossover inside, is a passive crossover. If it's powered speaker than its active crossover, there usually don't have as much control over the width of the field cover, so usually they have to be used in tandem with multiple three way speakers. If you ever got a really big rock clubs that have three way, speakers said, I'm she'll see like a big grid of them, a different angles and pointing in different spaces, depending on the size of the venue. Um, but three way speakers of the most common type of speakers you'll see lina reyes are are usually because they're becoming mohr common. They're usually much more expensive and for bigger events and festivals, but a lot of cheaper speaker cos they're not cheaper, but more affordable speaker companies are coming out with lina ray models like j b l, for example, has the v tack siri's they're becoming more common and not just the astronomical price that most people associate them with lina reyes are by far the best type of speaker to use for live sound applications because you have so much control over the coverage every single one of those elements could be individually adjusted toe fit the needs of the room instead of one speaker that's just sort of like throwing air, pushing air out into the into the room. Um, most lina reyes, you can use computer alignment where you actually like, put in the dimensions of a room and build sort of like a virtual version of the room and then load what type of speakers you want, and they have computer programs that will allow you to show where you'll hang the speakers and what type of because they are. And then it will calculate the best angle to set every single element at in that room to get the maximum amount of coverage without avoiding to with avoiding too much reflection. So those programs make it a whole lot easier than just the guessing game of trying to figure out where the best place to put the loudspeaker is based on just hearing um most of the time, thereby amped they do have passive uh, there's definitely are. There are passive, um, liner elements, but for the most part it's a lot easier just to run axl are two line level to each of the elements and have them be by amp so you're not running a lot of cable. It just kind of depends on what what they are, um the final thing was setting up speakers is to understand fay's correlations and time delays because a lot of times when you have two speakers that air setting the same program material in the same space the distance between those speakers matters a great deal especially for the listening audience if you have any speakers that you're putting in further out into the house other than right on the front of the stage the further out to get them or out of phase they're going to be with the main program speakers on dh so a lot of times you can actually program in time delays on certain types of speakers to be able to, um to get those s o typically what you'll do is if you have coverage you can create more coverage by adding more speakers and running them quieter but you have to compensate for time delays so this chart kind of shows and there's actually calculators on that are much more accurate where you type in the distance the speaker is from the main speaker and it tells you how many milliseconds to adjust the time bye to delay it so that they're in phase and they're not out of phase um s o a lot of these you know like this for example if it's if it's forty five meters from front of house from the front of the stage when the main speakers are you're setting up a second set of speakers you want to delay it by one hundred thirty one milliseconds? Those are all rough. This chart is just sort of a rough estimate to show you like I said, there's calculators online that actually you khun measuring to get exactly the distance you wantto want to adjust by s o let's go and take some questions um in the arch is the top of this is the top speaker louder since it goes back goes to the back and the lower one less power loud since it is closer to the audience that's a good question actually know for the most part we run all the speakers in an element equally because the longer the throw, if it's still out of the top it's it's not going to dissipate that much by the time it gets to the back, if there's too much dissipation from the from the front head of the speaker and the front plate of the speaker to the back of the audience that's actually noticeable. Then you would want to run a second set of speakers and time delay those but just the way that dissipation works, you wouldn't want there to be any difference in the front now the exception would be sometimes you run a front phil on a separate send on the console, so the liner is set up to only cover everything passed the first, you know, five rows, maybe in which case then you would set up separate speakers on the very front of the stage on the ground, and those would be a front feel that you could run much quieter so that those people in the first rows have a much better listening experience than people in the back. But typically, the way we mix these shows is you want the entire audience to have a very similar response, so you wouldn't want to run the front ones quieter and then louder for the back because the dissipation wouldn't really equal, um, in an all day festival situation, how does temperature affect the sound and what adjustments may be needed, for example, at midday high temperature than much cooler at night when headlining bands are playing, that is an outstanding question on it is entirely true that changes in any changes in the environment that effect the air pressure are going to change the way that the speaker's behave and act in the room. So a good example would be, I mean, even temperature changes, humidity changes, all those have a pretty big impacts on the room, typically what we do so we have, um, what's called a compass, which is a speaker control program that controls that galileo system that you saw that was underneath the stage. And that system actually has temperature adjustments built into the galileo system and actually make slight changes to the core of the curve of the speakers throughout the day. As the day gets hotter and colder and more and less humid, eso actually has sensors built in that sense those things, and as the day gets hotter, it actually changes slightly the the care of the speakers and then as the day gets cooler, it changes them back, so those air actually automatically adjusted his options within the compass system. It's not something we manually want to do because the changes air very, very slight, but they're definitely you know they're definitely possible, and so we let the computer sort of, like, handle all those types of changes. If you're not using a system that has that kind of advanced adjustment possibilities, I wouldn't really worry too much about the changes in temperature because trying to change the midday or estimate what those would be would be hard to manage. I mean there's like general rules of ground, how sound changes when it gets hotter, but it's not that it's it's, not that specific, so would be hard to sort of like anticipate what those changes would necessarily need to be the next stage once everything is sort of in place. Is you want to be able to find a way to tune the speakers to match the environment so there's a couple of ways to do that you can use actual analog graphic accuse for both the mains and the crossover delos sub subway for signal you can use speaker controllers like the galileo system that we use or you can even use the onboard queue for on the actual console and patch that across to the left and right mix in the subway first so that you can have some graphic you control I'm going to show you a couple different ways here we're going to show a video in a second house setting front of house up on then tuning the speakers using the galileo so isms are using the onboard a queue but I wanted to show you really quick the crossover that we use s o the galileo system is controlled by a program called compass here what we have is patching in three separate outputs we've got our sub par two mains on left and right and if you see those air high past one hundred twenty five hertz on dh then the third is our subwoofer which is low past right at about one twenty five and it's not a direct immediate roll off it's more like twenty d b per active eso setting the crossovers up this way allows us to send just to the subway for the low frequencies and then high passing the left and right main speakers to give the low and control entirely to the subwoofers. In addition to that, we can also go into input processing and used the graphic e q on the stereo input left and right, or the subwoofer, and you could make fine tunes adjustments just by adding in those individual failures. And the nice thing that I actually really like about the compass system is not only do you have a graphic you you also have a parametric e q that you can use that's kind of more of a standard, um parametric kiki that you'd see unlike an actual console s o this is really helpful, basically allows you to a map or an e q the inputs and the outputs of your speaker system before sending them to the subs into the mains. Now, how you actually go about doing this is a very specific process. You want to find the frequencies in the space, whether it's, the room or outdoor venue that are feeding back over under represented, and you use white noise to be able to do that. So we're gonna watch a video right now and setting up front of house and how tio use a reference mike and a rt a, um to analyze the room and tune the speakers to match the environment. Yeah, so we're gonna roll it over there. We're going to tip it this way and these are the feeders and we want the phasers to face that way. We're gonna tip. Then I'm gonna turn around this way. Cool. Then you grab that side and we lift it up down here and wait, wait, wait right here. Yeah that's my rig costs after the scythe. So we're here in front of house were just getting set up the crews on stage getting the speaker's phone and we're gonna start setting up the front of house counsel. We have an avid profile. All the pre ops for the consul are actually on stage and we're running an ethernet snake back too back to the council here and we're gonna go ahead and get set up. It's, real simple stuff, mostly just getting the screen up the mouse the brain, which is this piece over here in the council getting that setup, I'm patched into the actual desk deck, and then once we get power and the snake run from the stage to front of house, we can start to send some signal to the speakers once they get flown and we should be good to go cool, so we're gonna talk about how to tune speakers once you set up in any unique environment. The sound is going to change based on the speaker response where you put the speakers how the room is what the reflections are everything from barometric pressure, humidity, temperature all that has an impact on what the speakers are going to sound like in anyone given circumstance so before we ever start sound checking the first thing we want to do is set up to the speaker's to all those environmental changes the way we do this is we're actually going run pink noise through the p a and we're going to set up a reference mike which sits right in front of my mix position right up here on the reference mike we're going to patch into my computer and use what's called an rt a or real time analyzer basically a frequency analyzer that's going to show me the frequency response of what that microphone coming in looks like know what I can do because I know what that line is supposed to look like based on what pink noise line is supposed to look like and you may be asking what pink noises so first of all before pete knows you have white noise and white noise is basically a signal that gets created that's every single frequency at the exact same volume so it sounds like your tv turned on channel three or whatever it's basically just every frequency coming through so it should be completely flat the problem with that is that most sound starting with the lowest frequencies that twenty hurts as you go up every active you lose barometric pressure used air pressure or spl pressure as the frequency increases so pink noises white noise has been run through pinking filter in order to compensate for the loss in spl density as the frequency increases so there's sort of an inverse relationship between frequency and sound pressure density as the a cz the frequency goes up, the density of that basically air power decreases s o pink noise compensates for that and creates a white noise type sound that comes to the speakers that should be an accurate representation of flat frequency response sounds like a lot of crazy science, but basically what happens is it's giving us a reference point by which we can tune the speakers using a graphic cue to make the speaker sound is flat and linear as possible, which is our goal so first thing we're going to do is we set up the mike as you can see here on the screen we can see the sound coming in it's nothing come through the speakers right now except for just ambient noise from everywhere, so we're going to go ahead and bring up um a pink noise generator on we're going first of all route it to, um left and rights and the subs were gonna do these a little bit separately next thing we're gonna do once that's routed turn it off routing mode so you go to the outputs choose the and pull up a frequency are graphic on left and right so you can see right here this is sort of the graphic we're gonna go and reset this put it at zero um and now there should be no change being happening to the left and right mix just to make sure we're also going to go to one of the matrices and make sure there's no e q on that um looks like there's not so now once we're ready when he wouldn't turn on the pink noise that's what the peak noise sounds like it's going to come through the speakers to be loud so I'm not going to talk during this but what's gonna happen is I'm gonna put the on the fader so I could make some adjustments and then I'm gonna look at the arte on my computer that's feet being fed from the freak of the reference mike and make adjustments until I could get that line to his flat as possible then I know that the frequency response is an accurate representation coming through the speakers of what um what the signal actually should sound like so here we go wait um when you're started to this that first it takes a lot of time in practice you want to try to get the line is flat as possible there's. Also some artie, is that allow you to send a direct signal of the pink noise as a duplicate line into the that's. Really helpful. Because then you have the exact reference point and the line coming from the mic, and you just try to change the balance of the lines match up as much as possible. Um, there's also programs that do this automatically for you. A lot of signal processors, speaker processors, there's, a program called smart that's really, really fine tuned and helpful that allows you to actually create a computer program to go in and analyse the too frequency lines, the pink noise directly and the reference mike and fi tell you exactly what changes to make to the graphic. You and then there's even really advanced speaker systems that constantly have the setup and fine tune in real time throughout the show. So as the day progresses and the temperature changes, the humidity changes. It's, making fine tune adjustments to the graphic of the speakers to match any changes in the weather. That might be affecting the way that you're hearing it all these air options obviously depending on what equipment you have and what you're working with, you have to sort of figure out the best way to do this they even have iphone aps now where you can plug in just a microphone straight into a reference mike straight into your iphone and look at the screen and see what the frequency response of the microphone is there if you have a small system, you could do that even just with an analog graphic holding your micro for your iphone up trying to match his musters possible the key is you just wanted to whatever you possibly can to try to get the speakers to be as linear and flat as possible before you start sound checking um that way any problem frequencies that might come up during sound check you've already dealt with with the room and you know you confined tune on each of the individual tracks themselves we're here we're going to go and look at the tech finder and look at the first man who just got here they're starting to start loading on stage if you look at the tech writer it's actually pretty simple writer for the first band which is nice waken sort of soft roll into this festival is we start they've just got to uh stereos are one stereo sand one for left and right um a stereo keyboard, one guitar mike and leading backing vocals so it's super simple, really easy it's two people looking at the stage plot I can see that the the the eyes for the keys and the sampler are, uh, upstage center so we're gonna go ahead and use probably the keys one and two for the stereo send keys three and four for the keys guitar one for the vocals, which looks like it's off stage, right our guitars off stage right and then lead vocals. We'll just use vocals one too, so I'll go talk to jon kind of communicate this what we're thinking get them set up patched in so that once the p a is tuned, waken at least line, check visually and make sure we're getting signal out everything with headphones and we'll be ready to start sound checking as soon as the p a is on cool, so we're here from the house. We've got speakers being flown right now. I just met with john, the monitor engineering we kind of walked through what we're going to be using for the festival patch face the concept behind the festival patches that you're going to set up a cz many possible mike's as you can to cover any sort of writer that you're going to see that day. You know that you're not gonna use all of them, but then when the van comes up, we know from a hard patch. Um what? Uh, what tracks on the writer that we want to assign toe, which channel on the hard patch and then once we agree, when that on each sound check, I'll come back here to front of house and I'll pull up just tracks that we're using for that specific input list for that band. And then I'll set up the consoles with soft patch, which I'll show you just a second so that every band engineer comes up to mix the show it's set up exactly like there used to be exactly like the writer that they said, so we went through duplicated the exact patch that we had it monitors started drums, kick in, cake out snare snare bottom for tom's again, we'll probably use all four times just in case somebody wants it. Ride overhead. Left overhead, right percussion, one percussion to a couple open channels base mike based e I, uh, six mikes guitars to that dies four keys actually six keys to open channels we've got a bunch of vocals and we've got our talkback mike's at the end of an rmc mike it's, a wireless on stage so once I've set up all these on the channels that I need to actually pass soft patch in the patch bay here all the inputs to those channels that I just set up so I got from john exactly what the soft patch is gonna be and I'm just gonna go through and patch them in one for one channels one through forty eight on the stage box are exactly wind up with one through forty eight on my input list on my show control screen and then once I start mixing each band I'm gonna go through and uh when we pull up, the first writer will go through and decide which track we want to use for that specific writer and we'll hide all the other tracks and consolidate save it is a separate session and then at the end of that that band's performance will go ahead and reset back to the festival patch and you keep doing that for each specific band you keep it pretty clean, consistent and, you know, exact ellie, what channel's gonna be and it doesn't start to get away from you, but yeah, we should be ready to go on as soon as the ph phone will start uh piping some pink noise through the p a to do a little bit of ah speaker check with smart and then we should be ready to start loading in the first van we're gonna go and patching the outputs from front of house it's a really simple set up this year. We're going to set up the center field later, but right now, it's, just abc, um, left and right is going to a and b and c is gonna be the subs we're actually to set up the subs on a matrix output and the reason we're using a matrix, since it allows you to independently control how much your signal you're sending to the sub's independent of the main fader. So we're going to patch in left and right toe one into, um what you're coming up on the stage box under the stage, and then I'm gonna go to matrix and patch in three and label this subs in the final step something got options and change the pickoffs so that I want to make sure that the matrix air being fed, um, pre fader, on which they are right here in the matrix, um are being fed pre fader in both instances that way we know that the left or right mix, we're going to switch the prefect, so we know that the left and right makes us feeding the matrices pre fainter, which means that I can still send signal of the sub's, even if the favors totally down, which I'm going to start off with um, there's also way another way to set it up is to set up subs on aug san the reason I want to send it on aug santos if I only wanted to send certain channels to the sub, this is especially true with vocals were spoken more events where you don't want some one hundred hertz going to the subwoofer constantly because it's sort of creates sort of a muddy kind of mix so you could individually control which instruments are getting sent to the subs and most likely would be just kicking based on the new high pass everything, but we're going to set that up right now. I'll show you how we can do it. So for the outputs, instead of patching that channel three to the matrix, you just goto odds would set up on dogs for subs way would switch that channel three to be fed from, um, I'll put channel three to be fed from odd sixteen instead of matrix one, so we'll have both them there and it's all just a click of a mouse if I want to switch it. If there's any engineer that wants to mix subs on dogs instead of on the matrix, but for the most part, those are kind of the two most common options. There's. Also a way to set it up, where the crossover is actually setting to the subs at the speaker controller, the signal processor. That way, you have no control. Once you set it on stage, that sort of set, and you're sort of fixed with how much subs you're actually feeding the mix. I usually don't do it that way. Just cause there's not a lot of control, and if I really wanted to, I could just sort of tied the matrix on the left and right together, so that I'm feeding the same amount. Once I have a set amount I want, I want to do, and then I'd switch it back to post. Fader. Eso. Most part, we're ready to go. We're going to start making some noise out of the p a and start to power it on.

Class Description

Mixing Live Sound can be one of the most daunting tasks for any engineer. In this class, Zach Varnell will walk you through the entire live sound production workflow, from loading in a PA and rigging and flying speakers to soundcheck and mixing on the fly.

In this class, you will get to see an entire day of load-in from Seattle's Capitol Hill Block Party along with a complete breakdown of a live sound production workflow and interviews with some of the country's top touring live sound engineers. You will learn:

  • Scaleable components of a live sound PA
  • Power distribution and management
  • Tuning speakers with a SMART system and FFT analysis
  • Mic Placement and tips for an effective soundcheck
  • Mixing front of house
  • Mixing for stage monitors and in-ears

We'll also walk through a live mix setup and interview with two touring engineers from their FOH mix position: Adam Jackson and Andy Frost (FOH and Monitor engineers for Christina Perri) and Shane Bardiau (Twenty One Pilots).

Whether you are a working live sound engineer and just want to brush up on some core concepts or you are a new engineer looking to get into live sound production, this is the place to learn all about live sound in one location.

Reviews

user ee67bf
 

A very good overview of live sound presented by a professional sound technician. Good supporting video of a real event that Zach worked. He explained everything very well and I enjoyed the split screen views of his console work. Good job.

Cary Knoop
 

Extremely useful class and great presentation!