266. Busting Subwoofer Myths, Part 2

Picking up where they left off in Episode 265, Sean and Andy continue their conversation with Phil Graham and Merlijn van Veen about all things subwoofer, including whether or not to haystack, ways to deal with power alleys (and whether or not it’s worth the cost), and more.

Phil Graham started building hi-fi loudspeakers with his grandfather as a teenager in the 1990s and joined the B&C Group five years ago. Today, he’s the chief operating officer (COO) of Eminence Speaker, acquired by B&C in 2023. Based in Germany, Merlijn van Veen is a noted audio educator and he also serves as senior technical support and education specialist for Meyer Sound.

Episode Links:
The Cheese Grater (Horizontal Sub Arrays) by Merlijn van Veen
Redistributing The Error (Sub Power Alleys) by Merlijn Van Veen
5 Finger Rule (Calculating Decibals Without A Calculator) by Merlijn van Veen
Signal To Noise Episode 38 with Merlijn van Veen
Signal To Noise Episode 206 with Bennett Prescott of B&C Speakers
Eminence Speakers
B&C Speakers
Meyer Sound
Episode 265 (Subwoofers Part 1)
Episode 266 Transcript

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Transcript

Episode 266 - Busting Subwoofer Myths, Part Two, featuring Merlijn van Veen and Phil Graham

Note: This is an automatically generated transcript, so there might be mistakes--if you have any notes or feedback on it, please send them to us at signal2noise@prosoundweb.com so we can improve the transcripts for those who use them!

Voiceover: You’re listening to Signal to Noise, part of the ProSoundWeb podcast network, proudly brought to you this week by the following sponsors:

Allen & Heath, introducing their new CQ series, a trio of compact digital mixers for musicians, bands, audio engineers, home producers, small venues, and installers that puts ease of use and speed of setup at the heart of the user experience.

RCF, who has just unveiled their new TT+ Audio brand, including the high performance GTX series line arrays and the GTS29 subwoofer. Be sure to check it out at rcf-usa.com. That's rcf-usa.com.

Music: “Break Free” by Mike Green


Andy Leviss: Hi! Welcome to episode 266 of Signal to Noise. I'm your host, Andy Leviss, and this week, Sean and I are joining back up with Phil Graham and Merlijn van Veen to continue our deep dive into subwoofers--you see what I did there?

If you haven't already listened to last week's episode, you'll want to hit pause and go listen to that one first, or you'll be a little bit lost in the null, so to speak. So go check that out first, and then come back here!

Now, let's pick back up right where we left off last week!

Phil Graham: A ported box, a typical vented box, which is most common by far, has a fourth order roll off built in, so that means that like, if you do a fourth order, Uh, uh, uh, uh, high pass filter to protect the box from excursion. You're, you know, that's an eighth order roll off at the bottom of the, of the spectrum. 

Merlijn van Veen: which tends to be the rule and not the exception. 

Phil Graham: Yeah. So yeah, a lot of people do that. Um, and I know some of that comes from the old days where people didn't have PEQs around, so they couldn't like juice the corner. So you'd have to, typically it's a, then a box gives up real quick after the, after the tuning frequency, you don't want to go too much below that. 

So people, you. 

Sean Walker: sorry, I'm sorry to interrupt. 

Phil Graham: No, go ahead. 

Sean Walker: Are you guys finding that Like you just said that today's manufacturers kind of all got their poop in a group and all their stuff is pretty much, pretty much good to go out of the box because they've already got a lot of that built in. Are you finding there is a lot of need to. 

Re highpass the subs low or re lowpass the subs low? I mean, it seems like the presets are, and I say preset as in like the amp preset or the preset on the box, right? Where it's like, oh, we're in 30 to 60 cardioid or not cardioid or whatever. Like those seem like they're already pretty well designed and you don't need to do a bunch of fussing to get it to sound good, right? 

Phil Graham: Yeah. Yeah, I mean, this is, this is more for learning and your education and going back to the question of what were some things you could do to push, push out? And you know, in my case, I had the luxury of, luxury, uh, I had the experience of doing this in, frequently in churches with, Kind of hodgepodge boxes, not not powered, and with DSP. 

So it was like, it was all hands on deck, fair game to try anything to try to, to improve the spon response to the system. But today, I, I, I'll go back to what I said before. It's like if you trust your manufacturer, which you probably did 'cause you bought the product from them, it's, it's worth running with what they've got and not trying to reinvent the wheel, but behind the scenes, this is the kind of stuff that's happening. 

So. 

Sean Walker: Totally. Absolutely. And then back to rolling in the hay, is there a, uh, man, how do I ask this? And sound less stupid than I am. Is there a range of haystack that is, uh, that is preferable, but, like, what's the range of haystack where it's going, hey man, this is gonna add the heat that somebody is probably lacking in their mix, which is why they've got a haystack in the first place, to this is absolutely just what are you doing to the PA right now, like, where's that range of like, how many, or not, or whatever? 

Or is it all personal preference? 

Merlijn van Veen: So, so here comes our favorite answer. This is, this is the answer that we all love. 

Andy Leviss: Is this the Pat Brown answer? 

Merlijn van Veen: It depends. We, uh, myself, Roger Swenkey, and Bob McArthur, we published an engineering brief for the AES a couple of years ago, where we showed that different music genres have different C minus A levels. And you might be thinking, what's C minus A? 

Well, we have our A weighted sound level, and we have our C weighted sound level. And as of late, you know, we like to look at the differential between those two. And it turns out that different flavors of music go hand in hand with different C minus A levels. And so C minus A is a very first, uh, is a very good estimator. 

Of the expected low frequency content and, and, and Phil indicated earlier that he likes to do the heavy lifting with shelving upstream. Oh, that's, that's just a justifiable approach. Other people prefer to roll in the hay like yourself, but the, the, the, the challenge is one of the same. You want to build in a certain low frequency emphasis into the system, right? 

And we can think of several links in the signal pathway. You get to do that. I think the Haystack is, is less heavy lifting. It also has some disadvantages and whatnot, but how high that Haystack will be is clearly a function of content because for spoken word, you may as well leave the subwoofers at home. 

Hell, you're probably not even going to set the vocal microphone to the subwoofers to begin with. Uh, if you're doing a Broadway theater or theatrical applications in general or classical music, you're not going to do an 18dB Haystack. Um, but if you go to Latin American, they're probably going to have a. 

Completely different opinion on that. 

Phil Graham: Yeah, Sean, I found it to always be. And again, in retuning installs, because that's my most recent experience, was very much dependent on the customer. If it was just me, what I would do is, I would try to simulate the pressure pot gain of a small room. Because that's what most people are used to. Listening to like some studio monitors or home speakers in a smallish room. 

So you get a 12 dB per octave boost in the low end. And you just kind of have to pick to taste what frequency that starts at. So I would try to simulate that. To kind of have the slope, sub slope up 12 dB an octave, below a certain point. But then the customer could come in and want way more. But, they almost never wanted less. 

I usually tend to be on the thin side. So, they would want more and you could shelve it, but also you get to a point where the shelving doesn't do it. The other trick I would recommend for everybody is like, if you're complaining about punchiness and you're not happy, try taking a parametric EQ at 90 to 95 hertz and just boosting it a few dB until the system gets better. 

It's amazing how many times people were not happy with what punchiness was, and really, at least from my experience, it turned to be, how much 95 is in the mix, in terms of kind of getting that tactile vibe? 

Merlijn van Veen: I want to go back to Sean and give a little bit more of a, of a, uh, qualitative answer, uh, because, um, I think about a year ago now I shared a post, which showed the average target curve for three major manufacturers that shall remain unknown. And, uh, you know, there are, there are certainly, uh, agreements. 

So I'm now Offscreen, I'm now quickly going through those photos because I don't have the numerical value, uh, uh, on standby. But by the time you get to a hundred Hertz, give or take, uh, they all tend to be in agreement and it puts you around, uh, the plus 10, plus 12, the B milestone with respect to one kilohertz. 

So if you look at the average response of those manufactured target curves come a hundred Hertz, you know, you're already at plus 10. With respect to the one kilohertz watermark. And, and I think, I think, you know, I think that's a, that's a, that's a justifiable starting point now, whether it suffices for everything from reggaeton to, and whatnot, that remains to be seen, but that's what, what preliminary observations suggest, 

Sean Walker: And so, uh, as the music changes, you're saying that the mix does not change as much as one might think, but the haystack of the PA changes to compensate for that? I would have thought that something that needed a bunch of low frequency content would have been mixed that way, or maybe it's a combination of the two. 

But, uh, what I have found is when I have a big haystack, I can't mix as full as I would, right? Being an old studio guy, typically speaking, my drums and bass are banging. And I can't do that if I got a big haystack because it's just too much. So I keep flattening that bad boy out and have less and less hay every time because I'm like, Oh man, that, it's, the recordings aren't what I'm used to hearing, right? 

Because the haystack's too big. So, I have found that In my particular case, I need to tune to what, uh, the festival will like, and then I have to low shelf the absolute fucking shit out of it, so that I can mix to what I need. Because, uh, if I, if I mix to where my kick and bass need to be for recordings, for me personally, it's just blowing up the outside world. 

In my particular case, for recordings, I need my kick drum to hit minus 5 VU and my bass to be at 0 VU to the recording. Which means if you've got a 15 dB haystack on your PA, You're literally all kick and bass. But when you listen to that on a recording, you're like, Sounds like a modern rock record. 

Sounds great. Right? So I need to shelve out what I don't need, but when I do that to other people, they go, what's wrong with the PA? You know what I mean? If I, if I tune to what I need, every other engineer that shows up goes, your PA is broken. Like, where's the subs? You know what I mean? Is that, uh, is that just me being a whack job? 

Or is there actually something to that? You guys are dancing. I like this. Somebody say 

Phil Graham: Well, I mean, I share your opinion, and part of that is born out of, you know, the last 10 years, all the mixing I've done is in church, on an X 32, and so, like, that goes out to some people with TV speakers at home, or listening on YouTube, and I want it to sound good. I want it to sound right, and I don't want to have a bunch of EQ on the matrix sends to make it work. 

So, I'm with you. I like my PA way thin compared to most people. But, I think history would suggest that people have looked at me the same way they looked at you, Sean. So we apparently are in the minority. 

Merlijn van Veen: know, I, I, I, I, I I'd like to say first, I think there is no right, there is no wrong. It's about personal preferences because the, the mission objective is one and the same. We want to emphasize low frequencies because we want to make the kick drum sound large and alive. And, and so it's about how to get there. 

But, um, there, I think there are advantages and disadvantages. I think if you have a haystack, I think that if a haystack is in the system that a, Um, I'm not going to say inexperienced engineer, but a, um, somewhere in the middle tier, if that person walks up to the console, he's going to get to a place pretty quick where he's happy. If your system is unusually flat, it, it means that you have to do way more heavy lifting in the console and you can get a equally good, uh, Results arguably even better, but that is completely contingent on an experienced engineer. If you now have a middle tier engineer walking up to the system in a festival situation, as you brought up yourself, that person is now going to be in trouble. 

But I'm going to give you a reason why you might want to, you know, keep that haystack under control because especially in smaller situations, what if you're also responsible of doing monitors from the front of house console? You know, you have a huge haystack in the system. It means you're going to cut all your lows, which may be justified for the PA that's facing the audience. 

But whether that also serves your talent on stage remains to be seen. 

Phil Graham: That's a great point. 

Sean Walker: Yeah. And if your subs are not incarcerated as a lot of small systems or not, you've got all that base on stage two. Right? All that low end on stage two, which is a, it's a delicate balance because the audience wants to rock and the lead singer does not want to rock like that usually. You know, not, not like the audience does. 

That's, that's a heck of an experience if you're just getting slammed with low end from feet away. You know what I mean? While you're trying to perform, 

Merlijn van Veen: You mean, you mean a good pummeling? 

Sean Walker: YAY! Totally? 

Andy Leviss: kink shaming. 

Sean Walker: Totally. 

Oh, totally. Uh, okay. So is there, uh, man there have been a few measurement target curves floating around. Are there some that you have found that you prefer or don't prefer, or do you have some that you could share? 

Merlijn van Veen: Am I the only one? Okay, there we go. Sean's back. So 

Sean Walker: um, no, I'm here. Do you have, do you have something that you could share? I've got, I've got some that I really like a lot of pieces of, but like, uh, but not all of them. 

Merlijn van Veen: I would say, start looking at the, at the Discord server. I think a lot of, uh, fellow colleagues have been very gracious. Um, with sharing curves over there. Um, some of the curves manufacturers publish it's in, it's in their documentation. Uh, you just need to go through the documentation. Uh, I think a target curve is interesting. 

Again, if you have a festival situation with different guest engineers and whatnot, I think then it's interesting, but, uh, we have a target curve and I would never use it for, uh, for a theatrical application. It would be overkill. So again, it depends, which we don't like to hear. But. Sorry for being the bearer of bad news. 

Sean Walker: No, that's fine. That's, that's, that's how it is. We're, we're fact finding today. We're busting myths. You know what I mean? Mine included. 

Phil Graham: I did have an experience for a season where there was a particular integrator that would do a very flat curve. So you'd like put smart out, and the curve was kind of a straight line. And, uh, that was always unpleasant. So I suppose if there was a rule, a gentle tilt from more lows and less highs of some flavor is probably about right. 

Merlijn van Veen: There, there, there is, there, there is, um, Howard Page, which y'all know. Um, he once did an AES presentation on shelving the low end. And there's, I mean, and I have no dog in this fight because, you know, I can, I can do it either way. I can do the, I can do the hay, the hay, uh, the haystack, or we can do the shelf, or we can do any combination of the two. 

So I have no dog in this fight. But one thing that stuck with me is something that, um, That Howard Page said is that, uh, you know, these, these artists put a lot of effort in having those albums recorded and produced and whatnot. And so there comes this sign off process. There is a point in time where the artist signed off on the amount of low frequency content that made it onto the album. And I'm just, you know, I'm just gonna leave it there. But that's, that's interesting. In and off of its own 'cause the artist. Who is incapable of hearing the, the, the, the audience facing portion of the PA system. That artist nevertheless, at one point in time, signed off on the appropriate amount of low frequency energy that went into that recording or in that album. 

And that's, that's something that stuck with me. 

Sean Walker: I think you're absolutely spot on correct. Having made a bunch of records in my life for, you know, nobody's to somebody's and back again. And then also mixed a bunch of live shows. I would say that that is 99 and a half percent correct. And that every single artist that I've ever worked for also wanted more low end than is on the record in the live show, because they want more impact. 

So it's, it's, Uh, yes, they signed off and yes, there is like, genres have different amounts of low end, you know what I'm saying? Like Nickelback has more low end than Led Zeppelin, right? Just as decades and things have gone on, uh, but everybody that, that I have either worked for or met or been in contact with does like a little more heat in the low end live than they did on their studio record. 

Cause it's fun. You know what I mean? 

Just, it feels good and it's fun, right? 

Merlijn van Veen: Yeah, but it's about moderation. 

Sean Walker: Yeah, it is, it's in perspective, right? It's like you said, in in moderation in a percentage window of where the record was. You're not, you're not mixing Led Zeppelin like it is Nickelback, for example, just 'cause those are two super different things in the same rock genre. 

They would sound inappropriate if you did, if you flip flop those, right? And so, uh, if you had a few db more, more low end in one or the other, nobody's gonna freak out. But if you flip flop those too far outta perspective, uh, you, you might get fired from the artist. 

Phil Graham: they were listened to in a completely different context, right? So it's like, the live show is in a much bigger room, typically, with much less natural low frequency of support from the room itself. So the studio had more low end almost by default. So, uh, hopefully it was well controlled with the studio. 

Bass traps and whatever else, but still had more low end. And then, uh, it was listened to at maybe 85 dBA, not 105 dBA. So totally different, uh, experience. 

Sean Walker: Man, I have, since I started learning measurement, I have started measuring a lot of recording studios. You would be sickened to see the traces in a lot of the recording studios and, and good ones, not just like somebody's home recording studio, but sitting in front of a, uh, 4060 4G plus or a, or a, you know, an 80 series Neve and going, what in the actual fuck is coming out of these speakers right now? 

Because, 

Merlijn van Veen: the prime example of that is nowadays you don't often hear that track that, that often anymore. But I, I'm happy to admit that I'm old enough to remember that IGI of the album, The Night Fly by Donald Fagan. IGI is the track that people would play time and again. And speaking of haystacks, by the time that track sounds right on a large scale PA, you got the mother of all haystacks. 

And so going back to Sean, I'm not judging. It's just, I'm, I'm, I'm genuinely curious to how that would sound. Came into existence because that track is notoriously void of low frequency content. And I challenge anyone just feed it to a spectrum analyzer and, and look below 125. And I love that album and I love the artist again. 

Don't get me wrong, but speaking of. Uh, transferring the recording experience to, it's like, I don't know what went on there. 

Sean Walker: sure, well, uh, I don't know that specific track. I, I know the artist you're speaking of, but it, Uh, I know of the artists you're speaking of, I don't know them personally, uh, but what I can say is almost universally, yeah, fair enough, yeah, almost universally, uh, recording studios have a giant frequency gap between the tops and the subs. 

About 125 to like 60 or 80 has a giant hole in it, like 12, 15, 18, 20 dB hole, because uh, by and large. They don't want to put some digital nonsense between their analog nonsense, and they don't want to fix it, right? And so what I didn't understand for years while I was coming up in the studio and dealing with this, trying to figure out how loud my kick and bass should be, because it was never right, you know what I'm saying? 

With that, how are you going to mix that? Uh, was that the very small basics that we do every day in live sound to try to just sort out our PA, sorts out a recording studio in a freaking heartbeat, you know? And then you can actually make sense of it, but that needs, speaking of, it depends on target curves, way less tilt or haystack than you would in a live sound scenario. 

And what I found is something like a straight line from plus six to zero at 20 to 20 is a much more appropriate place for a recording studio than say the The target curves that are flowed around discord for a live sound system, in which case the whole thing just goes in a recording studio and you can't hear a damn thing. 

It's coming out of the speakers, right. 

Merlijn van Veen: I think the job descriptions are also entirely different, 

right? In large scale sound reinforcement, the PA literally becomes an extension of, of, of the room becomes an extension of the PA 

Sean Walker: which is an extension of the mix, 

Merlijn van Veen: extension of the mix. And it's, you know, and so it's, it's part of your sonic signature, whatever we want to call it. 

Um, but I think, uh, most people agree that in a studio environment. You want to base the artistic decision making process on what is presented to you by the monitors without them impersonating their own or adding or, you know, imposing their own, uh, coloration. And, uh, the only way you get that is by having the studio monitors being the best next thing to a microphone cable. 

Sean Walker: totally. And, and having futzed a little bit and I, and this is kind of a question and kind of a, it's like, here's some experience and kinda of a question for you guys, cause you're smarter than me. Flat has never sounded good. Right? Like if, if there is no low end boost recording studio or live or otherwise, I have not ever found it to be a pleasing place to be, whether I'm playing recordings or making recordings or mixing a show, some sort of low frequency tilt has always been some place that, that, uh, is more pleasing to listen to, whether that is. 

An increase in the low end or a decrease in the top end to effectively make the same thing. A few dB of seesaw has made things a lot more pleasant to listen to. How that is accomplished or where it is accomplished I think have been different and how much is kind of the the crux of the the question is like where is this is kind of what people want to listen to. 

And where is, I'm compensating for my lack of low end in my mix, right? How much of that seesaw, or haystack, or however we're gonna do it, is Appropriate and just, Hey, it's my first rodeo mixing a show. So I don't really know how to get a tight low end other than just rely on the subs to go boom, boom, pow, pow. 

Right. Uh, do you have a, uh, an experience or thought about where that starts to take over from like personal preference or from, Hey man, it would be cool to have a little more heat to like, man, this is just, just a lot, you know what I mean? I guess I'm, I'm, I'm not really asking the question clearly, but like, are you finding that plus six is not enough in a live sound scenario and plus nine, 12 or 15 is more common for the haystack and that plus six just isn't doing it kind of a deal? Or is that just a personal preference thing that I just don't like as much sub in my thing because it's all in my mix already? 

Merlijn van Veen: Uh, I, I hear Bob in the back of my mind saying, uh, the right amount of tilt for a given application is the right mind, right amount of tilt. And how would you evaluate that? Well, I think the principle preset in medicine applies, which is first do no harm. So I think if the voicing of the system requires the engineer. 

To do less on the console, I think that is a good thing. I think excessive use of filters and whatnot is indicative of a underlying root cause that's not being acknowledged. But if the system is properly voiced with the application in mind, you walk up to the console and all you have to do is write faders pretty much. 

I think that's, I'd consider that a win. Now, whether that is, whether whatever tilt is baked into the system, whether that suffices, uh, uh, uh, for a singer, songwriter. Uh, or whether that also suffices for an EDM act, that remains to be seen, but the right tilt is the right tilt. And so, you know, it starts sounding like a broke record, but it depends. 

Phil Graham: Sean, when I was doing install, um, on, on these, on these processors that you hate, you know, the open form DSPs, right? With all the, uh, we have 

Sean Walker: Shoot me in the face, Phil. Why would you do that to me? Now I'm triggered 

Phil Graham: I'm sorry. 

Sean Walker: going to start crying in a corner. 

Phil Graham: So, in that environment, yeah, Merlene is not happy either. But in that environment, if I'm like, I'm being paid. You know, either for a fixed amount of time or by the hour by the client. And so what I ended up settling on was I would do a series of shelving filters. I'd have one that started at 2k and then one that started at 12k. 

I could bring them up or I could bring them down. I would have one at that started at 500 and I'd have one that started at 250 and I'd have one that started at Uh, about, usually about 90, 95, and I would, I could, I could shove them up or down, and pretty quickly could kind of like, scoop the mix, either, you know, scoop it both sides to make it brighter, which, you know, in a quiet church, people like a little extra top in that case, because it's super quiet compared to the, you know, typical live sound world, to compared to like, quite dark and, and safe, for, for, for the louder, If you've listened to me so far, you should know by now that I have 505 data set to my own computer, and it lets me do anything I want to do. 

So, I'm now a jury judge and I can make anything I want when I need to do it. of the shelving filter is set, you know, I'm using a 6 dB per octave shelf on the high end, and maybe the 12 dB per octave shelf on the low end, depending on the context, 6 or 12. So all I have to do is just turn the levels up and down. 

You could usually kind of like, get the balance to where the customer was happy for. I don't know that I have any learnings on what the customer wanted, per se, but I knew that, like, if I kind of did that across the spectrum, so I could either tilt it all the way one way, or tilt it, or, or bowl it for the quieter stuff, or have a, a, a real strong pressure prop gain, kind of, at the low end, you can get there quicker. 

Now, I don't know if I would ever try to do that in a system tech environment for a show, but at least in a, in a, in a room where you were trying to make the customer happy. Also, what that gave you is later when they called you back and you're like, eh, Phil, it's too bright. Or, you know, hey, I want more bass. 

I could just log into the processor and spend 10 seconds on turning a knob up, uh, down a couple of dB and be done with it, as opposed to, like, having to go back and revisit the physical space. 

Sean Walker: Totally. I get that. 

Phil Graham: But I don't know that there's a meta narrative. Andy, you've been quiet. Do you have an opinion on all that? 

Andy Leviss: I feel like I'm balancing the average back out for how much I normally do the talking. 

Merlijn van Veen: Well, I think it's safe to say that if you need more than six filters in general to get in the comfort zone, you have a bigger problem anyway. Here's 

Phil Graham: And that wouldn't be something you'd want to hand to a tech, a junior tech either. Just something that worked for me to kind of quickly get a, a, a target curve. Without too much fuss that you could just drop in as a processor block at the front. 

Sean Walker: Sure. Totally. And, and, you know, I, I'm getting the results that I want and, and ultimately there's results that my clients want because we're not getting fired very much, you know what I'm saying? I was just curious if there was like, Oh, Hey, this, you know, plus 15 or whatever thing that I'm doing and then having to shelve it out or like, I just want to see how far out of, out of. 

Normal, you know what I mean? If I was at a normal or not, and it sounds like not, sounds like we're just doing the damn thing every day, you know what I mean? Building it so that people are doing what they need to do because, you know, when people walk up to the rig, they're like, hey, man, that sounds great. 

If all, all things from this manufacturer sounded like this, I would, I would have thought this was a, you know, different, a whole different ballgame. But, uh, you know, it's just, it's just a check in, man. We're all, we're all engineers and half of this is science and half of this is art when you're mixing, you know what I mean? 

So. Uh, I was just curious how, how whack my, my situation was or, or anybody else, cause a lot of people are in, you know, it's not, it's not unique to me, I'm not trying to talk about me. A lot of people are trying to figure out where, how much low end in their mix or versus their PA or whatever. Like, this is kind of half the reason you guys have whole gigs, right? 

Like it's your, it's your whole job, right? You know, to, to chat about that. So um, 

Merlijn van Veen: the proof is in the putting, right? Um, on the last day of, of the, of the classes that I teach, we finally. Bring in the subwoofers and we compliment the main PA. And then we're going to audition some tracks. And then you got 30, 30 students in the class and I'm going to play a track and they, they have gonna have to raise their hand if they want me to increase the subwoofer volume or, you know, lower it. 

And so you got 30 people in the class, you play one song, you get 30 different opinions, so you find the middle ground. Now you play the next song. Now you're going to get 30 different opinions. entirely different opinions. So it, it, it depends entirely on, on, you know, on the content. But, but as Phil likes, you know, Phil gravitates to doing it with, Processing upstream. 

Other people prefer to do it with the Haystack. And I think that the big takeaway should be that there is no wrong or right. It's just about personal preference. 

Phil Graham: Yeah, and I think I would feel much differently if I was doing more shows. Like, I mean, I haven't done shows in a long time. The Haystack is much more expedient. In a, in a, in a system tech for your local corn dog rodeo, it's a, it's, it's what, it's what you should do, but in an install where you like need to go make measurements quick, quickly, literally in between guys putting up drywall, and you, it's very expedient to go quickly take some smart traces, and then just flatten them, right, because you can flatten them at home without listening to the PA, and then you can come back later and apply some, some overall shape. 

To that, that's much more practical and expedient to just target a flat curb at the speaker box itself, and then later on switch the overall tonality at at the, uh, at the array level, which is not what you'd be doing if you're out as a system tech. It's just the practical. Andy, how does that work in, in, in the, I have no experience in the, in the world of, of Broadway. 

How does it work in that environment? Is it you just, do you try to target a flat curve and then, and then shape it out later? Or how, how do they do that? 

Andy Leviss: very much depends, because it's going to depend on the design. I mean, on Broadway it is all a rental, so it is somewhat more of like the SE kind of line of things, rather than an install. typically aren't gonna have their own system. And, yeah, it'll depend on the designer's approach. Like, I've done, I've, and, like, is it a play, is it a musical? 

What type, like, if it's a, like a Rodgers and Hammerstein musical, it's, it's gonna be fairly balanced, it's, you know, that orchestral music, you know, if it's like Rent or, you know, Jagged Little Pill, like, you want it to sound like a rock concert. And so there's that balance to be had in that variety. I will say, when I've come in as an associate designer, or I've had one or two shows where I've been brought in just to tune the rig for somebody, Like, you know, I'll joke that I've been brought in to be like, you know, the mini me of Bob, but I'm nowhere near as good at it as Bob is. 

Um, but like, when wearing that hat, then I'll come in and start, like, particularly for theatrical stuff, very flat, because often that baseline you're going for is the very subtle, very natural reinforcement. But, but then again, just like with working with a front of house engineer, it's very much the great. 

Now let's listen, let's listen to like some typical content of what you're going to do in the show. And is this working for what you want or do we need to tweak it from there? 

Merlijn van Veen: And I think, Andy, you can also relate to, uh, when you have separate systems for the pit and for the vocals, it gets even more convoluted. Because you, uh, I would expect, uh, the system for vocals to be flatter, less tilt, 

Andy Leviss: Uh huh. 

Merlijn van Veen: maybe even a line array system, whereas a point source system for the pit, uh, probably is going to have some more low frequency emphasis. 

So now you have two, you know, target curves to contend with. 

Andy Leviss: Yeah. And often, and often two distinctive brands even, cause somebody will like, well, this, this brand is going to give me nice, clear, you know, book scene dialogue that I can understand the words, but maybe it's not, it's not, it doesn't sound musical to, to use the, uh, uh, The, you know, hand wavy terms that we so like to use in the audio industry. Um, so yeah, you'll see lots of that. Yeah, like an entirely separate system in both brand and design for, for the music side of it as for the vocals. 

Sean Walker: all right, so back, subwoofer question, if we can go back to subwoofer specifically. 

Phil Graham: go land the plane on subwoofers, right? 

Sean Walker: No, I mean, just, you know, you know, it sounds cool, but like, Recently, there have been a lot of speakers coming out that are already cardioid inherently, either in the box or whatever. Is that cool? How is that different than like making it yourself or with presets in a multiple boxes or like what are some of the trade offs because if I remember right you didn't like nobody's buying you free dinner or lunch or something right so like there's got to be a there's got to be a compromise in in both scenarios what are the benefits and compromises in in in those 

Merlijn van Veen: I just like to plan the seat on that particular example. There's two conditions that need to be met to have cancellation. You need to have face opposition and your levels need to be matched. Because if either condition isn't met. And you do the subtraction, which is what a polarity reversal does for you, there's going to be residual signal left over. 

If you're not exactly out of phase, there's going to be residual signal. If your levels aren't perfectly matched, there is going to be residual signal. So those are the rules of engagement, doesn't get any more straightforward than that. Phase opposition, match levels. Okay. Number two, when are you hurting for cancellation? During the downtime between consecutive kick drum hits or at the peak? That's another one that I want to plant. I think you're hurting for cancellation, not in the white space during consecutive kick drum hits. You're hurting for cancellation at the peaks. Now, component number three. Imagine now that you try to do this with different components. Okay. Maybe a little guy in the back and big guys in the front. How is the little guy whose job description is to cancel, keep up with the big guys when you're hurting the most for cancellation, which is at the extremes and not at the downtime between consecutive kick drum notes? 

Sean Walker: seems like that would be a challenge 

Merlijn van Veen: Well, the brand that I happen to work for, you know, used to be one of the early adopters with M3D. 

And um, and, and so I think you've got a point where you say that it's a challenge. But, you know, it's just, it's just, I just wanted to plant these seeds. It's like, keep, keep that in the back of your mind. When are you hurting for cardioid? Well, if you want to have maximum cancellation at the moment that you're hurting the most, you need to have face opposition. But most important, your levels need to be matched. Otherwise, there's got to be residual signal. 

Sean Walker: so so that if you're gonna have The same level and the same, you know, phase and polarity. You need the same size driver with the same motor and same power. And right. That has to stay consistent. So if you've got a, if you have a box that has a forward firing, larger driver and a rear firing or side firing, smaller driver, it can't keep up. 

Right. You got, you got a big, a big diesel engine, a little four cylinder trying to sort it out, right? 

Merlijn van Veen: I'm, I'm not, I'm not, I'm not, uh, religious about whether it keeps up or not. It's just, I, I'm inclined to believe that by doing it, by doing it with a playing field that is not level to begin with, by using different component sizes, I think you're introducing layers of complexity. That's the only thing that I'm, that I, that's the only thing that I am inclined to believe, but I can be persuaded otherwise. 

Sean Walker: Copy that. Okay. 

Phil Graham: My opinion is I would happily sell you two drivers where you would have previously bought one. 

Sean Walker: Totally dude. Totally. 

Phil Graham: There's my, there's my stuffed shirt answer. I think, I think if, if I was, not that I, not the world needs another speaker company, but, um, but I think if, if I was to build my own speakers, I would have some sort of directivity built into them. I think if you made it simple enough, everybody would see the benefits of it. 

And, but Merlene is right. I mean, the, the. There are a lot of subtle nonlinearities in loudspeakers. They're the least subtle when the speakers are the loudest, and generally when you need the extra acoustic thing, whatever that is, is when the stuff is the loudest. 

Sean Walker: Is anybody, is anybody in the world not asking more of their speakers than they were designed to? Even on the biggest shows is everybody like, Oh man, this whole rig is on cruise control the whole time. Like, aren't we always asking the world of our rigs? Aren't they always doing as much as they could possibly doing for truck size, PA size, client budgets, right? 

Like whatever it may 

Andy Leviss: Maybe with the minor 

Phil Graham: trying to run 

Andy Leviss: a Jonathan Dean's Cirque show. 

Phil Graham: yeah. I mean, certainly for guys like you, Sean, who have to keep their trucks busy, and, and you want to have the rig sized to the show, and, and the customer's only going to rent so many boxes, and you, I assume you itemize those things, so you've got, you've got, you've got hard limits on what you can do, so, for guys like you, absolutely, the rig is almost always sized to the customer, 

Sean Walker: Sure. But I've got acquaintances in. All sizes of shows, and even in some of the shows that, uh, you know, that my company has no, no part in shows of that size, they're still complaining about budgets and trying to get enough trucks, you know, instead of space on a truck, like in our particular case, it's how many trucks can they take, right? 

And they don't, they can't get another truck, or X amount more boxes means another truck and they can't have those more boxes, or they can't have those more boxes. Everybody's got a budget, man. No matter who that is, everybody has a budget, right? So, 

Merlijn van Veen: I don't want to, I don't want to put us on a different track, but I think there's also, I think people are justified to take the environmental concerns into consideration, 

right? There's that as well. 

Sean Walker: Like, if you don't need to send another truck, that's all the better, right? You know, I'm gonna have a hard time finding anybody that's gonna say, you know what, just send all the trucks you want. Who cares about the planet? You know what I mean? Like, 

Merlijn van Veen: Or, or hire all the PA even if it's idling. 

Sean Walker: yeah, yeah, right. 

Merlijn van Veen: so because I second Sean is like, I think it's still the exception rather than the rule. I think, um, most, uh, PAs, uh, are, you know, are, you don't want to overspec. You don't want to, um, you know, it's, you get to do that once and then the next time, uh, you're going to run out of luck. Um, so everybody pretty much wants to nail it. Um, and that means, yeah, 

Sean Walker: You're doing like, you know, 70 to 99 percent of what the PA can do. Sometimes you're doing 150 percent of what the PA can do and that's just the reality of life. Whether, whether or not it's correct, it's just the reality of doing shows, right? And clients and, because some of it's Not only educating ourselves on how to do it right, but trying to educate our clients on what they actually need because they see a lot of this and go, man, that is so much gear for what they see. 

They think is not a huge show. You're like, man, it's not just about being louder. It's about a lot more things like maybe not pissing off the neighbor next door that's really mad about this concert you're having or Whatever that may be, you know what I mean? You still want to hear it clearly in the back, I need more speakers so that I can do some nerdery to try to get some sound to the back rather than just killing the people in the front row and everybody looks like some Max L guy in their chair, you know, just, you know. 

Phil Graham: Yeah, and we're still trying to solve logarithmic problems with linear answers. I mean, speakers are, uh, are, the constraint of how much of a speaker moves in and out has not improved logarithmically over time. And hearing is logarithmic, so when you go from needing one box to needing 80 boxes pretty quick, depending on what the application is, because of just the way that we perceive sound. 

The same is true for lights, by the way. Lighting is the same problem. It's like, one light is pretty good, but then the next step up is like 80 fixtures, right? So 

Merlijn van Veen: about, I was about to say exactly that. Nice try, Phil. 

Sean Walker: Lighting is pretty, everybody can see lighting and that it's pretty, and they have a whole lot less sales to do than us, they can just say, I can be prettier than the 

Phil Graham: Well, when you're trying to meet 

Sean Walker: my pretty and give me your money. 

Phil Graham: When you, when you're trying to meet outdoor lighting requirements that are, that are, that are mandated by a government, it turns out the inverse square law is exactly the same problem that you have in audio. 

Sean Walker: Oh, that's 

Phil Graham: Yep. Lighting is, it's still butter on toast at the end of the day, and as the toast gets bigger, uh, the, the amount of product you have to bring gets big, gets a lot higher quickly. 

Sean Walker: I'm gonna let out a little nugget of sound company ownership for our audience. If you have lighting companies in town that like you, And they will hire you and they've already got the clients do that because their clients are already used to a giant ass bill and lots of big trucks showing up where you could just say, well, here's the price. 

And they go, Oh man, that's half of what lighting charged. Oh, thank God. 

Merlijn van Veen: I am now, I am now professionally teaching for close to 15 years and I once had a, a Lampy in my audience. I once had a lighting engineer that attended the class and I, until today and for the foreseeable, I will take my hat off for that guy because he wanted to know why it mattered to us whether his moving head lived over here. 

Or whether his moving head lived over there such that we could put a loudspeaker over there. And I, all I can say, kudos, that has never happened again, um, but, uh, 

Andy Leviss: was promptly fired. 

Merlijn van Veen: I'll never forget that. Um, that was, um, real professional courtesy cross, cross departmental. Absolutely. 

Sean Walker: Yeah, that was 

Andy Leviss: that's, wow. 

Merlijn van Veen: Exactly. 

Sean Walker: right? Cause like the, you know, we can all make whatever quips or jokes we want, but. Ultimately, it's a, it's a whole team and a package to make the show go together, right? Lighting, video, audio. You can't do it with just one. Otherwise it's boring or not, not really a show. 

You know what I mean? So yeah, that's, that's, that's okay. I got it. Back, back to subwoofers. Cause I can't 

Andy Leviss: So I got one last thing because I know we're going, we're going crazy long here. Um, 

Sean Walker: we're going two episodes, Andy. 

Andy Leviss: oh, absolutely, absolutely. We'll figure out where to cut this one 

Sean Walker: Yeah. 

Andy Leviss: We'll break it up into a couple of dog walks at a time. 

Sean Walker: That's what I'm talking 

Andy Leviss: Um, 

Merlijn van Veen: a 6db discount! 

Sean Walker: Yeah, dog. 

Andy Leviss: Um, uh. Merlijn, uh, I wanted to talk a little bit about, cause it, and I know we're not gonna go like super deep cause it is something that could take an entire article or two and that in fact you have written that article that we'll link to in the notes, but because it's something that has become a little bit of a popular topic of conversation I think in part of the Blame Ghost of the Signal and Noise Discord where it kind of bubbled up a year or so ago, and Sean and I talked a little bit about it an episode or two ago because we ran into this on a show Sean had. 

Where the classic thing with like left, right subwoofers is power alleys. There's, we won't get into proprietary names or not of what the different approaches to trying to mitigate that are, but as one of the couple of people in the industry has really dug deep into how ways to deal with that work or don't work and what the trade offs are. 

I was wondering if you could kind of give us just the kind of quick overview and then we'll point folks towards the article you wrote 

Sean Walker: Yeah, man. Where's my free lunch dog? 

Merlijn van Veen: It's, it's, uh, yeah, it's, it's, it's, it's fascinating. It's one of those prime examples where if you bring something up that everybody has forgotten about, except for a couple of industry veterans, you can pitch it as being something new. Right. And, and, and, and especially market, marketing departments are keen on this. 

You know, we're going to bring something back half a century and then everybody will go like, wow, that's mighty interesting. And why didn't we come up with that earlier? Well, somebody did. Um, so what, what you're alluding to, uh, is certainly not novel. And as you pointed out, it goes by a proprietary name that I shy away from because all of that. 

Um, but before we look at the why, I think there is a much more interesting conversation to have is. Why do we, why are power LEs so objectionable? Because in today's industries, you know, main PA is expected to go down to 30, 31 Hertz nowadays, and those lower octaves are subject to exactly the same issues of level left, right deployment, but nobody seems to lose any sleep over that. 

But when it comes to subwoofers  

Andy Leviss: I do, but I'm weird. 

Merlijn van Veen: Yeah, well, that's fine. I'm not judging, but I find it, I find it interesting that, you know, I call it double standards. It's like people don't lose any sleep over left, right main PA, which nowadays effortlessly goes down to 63, 31 Hertz. And those octaves are going to be subject to the same issue. 

But when it comes to subwoofers, uh, left right is, is, is borderline heresy, heresy. And then I'm like, well, the, the history of modern sound reinforcement, whether you consider the Beatles at Shea Stadium as T Zero or Woodstock as T Zeros were in the late fifties, early sixties, the only system that with, that has withstood the test of time is left right. 

And, right, and, and of all the other things that have been tried, quadraphonics and you name it, left right is the only system that has withstood the test of time. So that is just an observation, is like, why do we, why do we, why do, why are we okay with left right mains, but freak out over left right subwoofers? Anyway, it's because, it's not an issue to me. Uh, I think the audience will, you know, if, if it's not a seated audience, they will meander and they will go for a place where they're happy with the amount of low frequency content that is within their comfort zone. If it's a seated audiences, of course, you don't have the luxury to move about. 

But um, if you have a live thrive deployment, you can use signal processing to mitigate those power alleys and power valleys, bearing in mind that what you're effectively doing is redistributing the error. What you call power alleys and power valleys, I call that there's an error, right? We don't have uniform coverage. 

And so we're going to, we're going to redistribute that energy from regions where there's too much to regions where there's too little. And one way you get to do that, and this is what Sean and Andy are talking about, is by basically. Basically. Having the left and right subwoofers alternate on a frequency by frequency basis, so that for any given frequency, you're always in the sole custody of one side as opposed to two, as opposed to both sides simultaneously, and you get to do that by virtue of signal processing. 

Yes. 

Sean Walker: What are the some of the trade offs for that? Because, you know, something about lunch, right? Like, what, what, what are the trade offs to that? 

Merlijn van Veen: The, the, so, so one way of doing it, which is easy to explain on this call is you're going to, you're going to lift, you're going to use narrow filters, narrow parametric EQ filters, or, you know, your graphic equalizer, which I wouldn't recommend, but you're going to use narrow parametric EQ filters, and you're basically going to alternate. 

So you're going to lift one frequency in, on one side, and you're going to cut it on the other side. And then you move on to the next interval. You're going to do it exactly the other way around. You're going to push one frequency on one side. And you're going to come, so now you get this alternating parent pattern. 

The trade off and Phil can testify to this is that if you use narrow filters, you're going to get ringing, you're going to get filter ringing, you're going to get huge phase shift. And with that more group delay, or I would call it excess group delay by now. And the sustain, the rigging that is associated with narrow bedded fills, you get that, you know, you get that. 

So, um, I. It's a new verb, which is a thing. I audibilized this. I looked it up in the Webster Dictionary. It's a verb. I audibilized this in the article that Andy, uh, um, spoke about, but, uh, so you can do that with parametric cues, but you're going to get a more sustained, less dry sound because you're using these narrow filters. 

Sean Walker: Copy that. The reason it came up is that Andy was out here visiting as he was on his way to another show, and we had a outside show where we had, uh, a killer rig and a killer SE and it was all deployed great. And day one was awesome and totally banging. And then day two, the headliner came in and said, Oh no, we can't have the sub stacks that high. 

They were three high on a cart. Cause then you can't see my guy cause he sits down. And so we had to rip apart the sub deployment and do something else. And, uh, so we, you know, we got into this and, and ultimately everybody was happy and you know, the show went on, but it was not the same experience. Out front that it was the day before, uh, but headliner was happy. 

Headliner's engineer was happy and the crowd was happy. So nobody but us nerds knew the difference. Uh, it was not the same experience out front that it was the day before. 

Phil Graham: I think, I think it is, I don't, I don't know this technique. In fact, I learned it from the Discord. Discord. It's completely new to me, something that I had never learned about until a year ago, or whenever I, I, I, I jumped, I jumped on the Discord when Ben, when Bennett was on the, was, was on the, on the show previously. 

But I do think it is worth mentioning that any time that you have a, a, a change in filter response, you have phase artifacts that come along with that. So, there's, you can think of, uh, the world as, uh, The world can be defined kind of as minimum phase and excess phase. Minimum phase is kind of what the math tells you is the minimum amount of phase shift that any sort of change in frequency response causes. 

And then there's excess phase. An excess phase is additional phase response shift that you can have from the type of filter. And so speakers are kind of Minimum phase, they're close to it, so like a speaker driver, like when it rolls off at the high end and the low end, the phase shift you see in the driver is more or less reflective of the minimum phase shift that you have to have to have the high frequency roll off and the low frequency roll off, because time and frequency are linked. 

And then crossovers and other types of filters. Can be minimum phase or they can have more than minimum phase, they can have extra phase in them. But either way, the universe defines that if you have a change of magnitude response as you see in a frequency response graph, there is a time, there's a time penalty for it. 

So, and you can have a minimum time penalty, which you can't get rid of, which is by the way everything that vibrates around you. So anything around you that has a low frequency oscillation is, Mostly minimum phase, most mechanical systems are pretty minimum phase, and so, you're already used to energy being spread out in time in a low frequency, when someone bangs a gong, or closes a door, or when you sit in your car, like, your brain is already pre wired to have some extension of the energy in the low frequency. 

Because you have a resonance and because that resonance has a frequency response, it also has an effect in the time domain. But then in the world of electronics and filtering and DSP, we go a step further and we can actually add additional phase. There's, there's two ways to think of it. So in some sense, we're more, more tolerant. 

Obviously we're more tolerant to group delay in the low end, but, but we can, we can make that worse. And I think it's a question of, of whether the trade off is worth it. And I've never used this technique, so I don't know if it's worth it or not. 

Merlijn van Veen: Well, and I think that's what's, what I think that goes back to Sean's original question is like, what's the trade off? Because you're solving one issue, which is your, you know, you're getting rid of your power alleys and power valleys, but to do so effectively, you need to have narrow filters and to achieve what we call isolation, you know, one side for a particular frequency needs to dominate by at least 10 dB over the opposite side. 

And so those cuts and those boosts are going to be significant. You know, and so narrow queue and a lot of boost and a lot of cutting makes the slopes even worse. So you get more sustain and whether that is acceptable to you or not, well, that's, that's, that's everybody's prerogative to do, you know, to discover for themselves, but it's not new. It's just everybody has forgotten about it, so it becomes a shiny new thing and that is always a little bit scary to me because, you know, shiny new things always at first are used too often and for the wrong reasons, and then everybody comes to their senses. So that's something that scares me. And the other thing is that the technique that Sean is Talking about, by virtue of the cue, should not be mistaken for that proprietary technique that is, uh, used as the colloquialism when people talk about this technique, um, and because that's something completely different for which you'll, you'll have to read the article because we won't be able to do that on this, on this show. 

Sean Walker: Sure. And, and, you know, to kind of just go back one second, I, I was not suggesting it did not sound good. It was fine. Everything was fine. It was just not the same impact or experience as the day before when everything was super tight in time and, and, you know, phase and polarity because on that particular show, I was blessed with a world class SE that came out and the rig was stunning. 

Day one and day two, I was like, oh man, that kind of just sounds like everything else was, you know, any other rig in the low end because the headliner had asked for changes, not, you know, not due to us or the SE or anything else, just that like, well, here's the, here's the best we're going to be able to do to accommodate your, your needs, your unique needs that have nothing to do with audio, right? 

Like, so it all ended up just fine and sounded fine, you know, but 

Phil Graham: mean, at the end of the day, it's a service industry for all of us in this table, 

Sean Walker: a hundred 

Phil Graham: right? And 

Sean Walker: And if we think we're in any other industry, we're wrong. 

Phil Graham: and then also, I think it's a, that group delay is audible, right? So you, 

Merlijn van Veen: It's, it's, uh, yeah, yeah, we can, that's, the danger is we can continue to talk about this for hours. 

Sean Walker: ha ha ha Oh man 

Andy Leviss: So we're launching a new podcast, it's called Only Subs. Wait, sorry, I just listened to what I said out loud, that's a different, and on  

Merlijn van Veen: it's gotta be, it's gotta be subliminal. 

Sean Walker: There you go, there you go, totally. 

Andy Leviss: go. 

Sean Walker: All right, let me ask you guys this. Since we're crushing into two hours right now. What are some of the things that I, I, or we should have asked that we didn't Or that you were hoping we would ask that we didn't Like, what are some things that you were just like, Yo man, I want to talk about this and you guys weren't smart enough to bring it up. 

Merlijn van Veen: If it, no, I'm happy that we briefly talked about subwoofers being claustrophobic, you know, we're talking about wavelengths the size of mini Coopers to intermodal shipping containers, 40 feet. So they're claustrophobic, don't fence them in. Of, of everything that was said on this. Wonderful show. Uh, if I had to evangelize something, I would say, keep in mind they're claustrophobic. 

Sean Walker: And then, the other big takeaway from, from Phil was, size matters. 

Phil Graham: Yeah. Well, I mean, there's, yes, yes, yes, it does. Uh, 

Sean Walker: And yes, we're still talking about subwoofers. Yeah. 

Phil Graham: I, I mean, I think we could talk more about how speakers work, but that, that could be a whole separate show too. I mean, speaker drivers themselves are by far the most non linear component in your entire chain. And, and unlike something like a plugin where you can kind of make the nonlinearities good and work for you, you don't always get that luxury with speakers. 

And then on top of that, um, the boxes matter a lot. I mean, if you look at the industry, all the boxes, if you just like, took your grandma off the street and land them up in a row, she'd be like, wow, those all look pretty similar, but obviously they're not similar at all. So there's a lot of, there's a lot in terms of subtlety and physics that isn't just obvious by looking at a black box with a metal grill on the front of it. 

Merlijn van Veen: Yeah. And, and, and there, there's one more thing which we didn't speak about because we talked about deployment, but we didn't talk about the modeling side of things, right? Because a lot of these configurations we try to visualize in our software and whatnot so that we can forecast their behavior in the field. The other thing that we need to, um, bear in mind is that the, uh, software that is shipped without loudspeakers, typically for free, uh, still, as we speak, relies on the point source method. And the point source method uses infinitesimally small sources with no physical dimensions whatsoever. So, keep that in the back of your mind, because if you park two Mini Coopers in front of each other, It's going to take sound some while to wrap its way around such an obstacle, not within the confinements of your software, because in your software, get what? 

There are no loudspeakers. There are points in space with no physical dimensions that represent data sets, but all those interactions that happen in the real world. For all of those software that ship with our products are not accounted for by the point source, point source model. 

Andy Leviss: That's, that's a big one, there's one of the biggest things about learning how to use those prediction tools is learning what they're not gonna tell you and what they're not gonna show you. 

Merlijn van Veen: Yeah. Stuff like 

Andy Leviss: again, not, not, not 

Merlijn van Veen: but 

Andy Leviss: Yeah, and like not to throw like any particular brand under a bus, but like one of the, one of the brands that makes single box cardioid boxes, it is a known limitation of the software that even when it's dealing with phase cancellation, will not model the changes you get when you tight pack those boxes so that you don't have that path around them and they don't cancel the way they were designed to. 

It'll model great, and then you tight pack those subs and suddenly your directionality is completely different from what you were modeling because it's a limitation of the modeling software. 

Phil Graham: I mean, you're not calculating local acoustic impedance around the devices and without that you don't get the real thing. But now you're talking about simulation at the design level. 

Merlijn van Veen: it, it matters because, uh, a lot of these more exotic arrays are being deployed because the software or the predictions that are shown in the software are treated as religion. And while not taking into consideration as you brought up yourself local impedances and whatnot or tight packing and those kind of things. 

Now we're all aware that there are solutions out there that actually allow to compute that, such as boundary element method and whatnot, but not if you have a show at a quarter past eight. Uh, it might take a couple of more generations of, uh, of, of laptop computers before we get to do that in a, in a timely fashion, but that's 

Andy Leviss: I will anxiously await map quantum. 

Sean Walker: But that's, I mean, but that's real, that's real life stuff, right? Shows at eight, man. It can't take ten years to compete. Like, shows at eight. I showed up for Walkin Chalk, and now it's gotta be frickin ready to rip in a few minutes, you know? 

Merlijn van Veen: but that, that's another one. So don't, you know, claustrophobic, don't fence them in and do not treat your prediction software for the very low frequencies that we're talking about. Always keep in the back of your mind that within that software, all the interactions that real loudspeakers. undergo in the field are not taken into consideration. 

Sean Walker: And so, when you say claustrophobic, and you said about a meter or three feet or so, you're talking about, don't put them under the stage, obviously, and then also, three feet, if the stage front is solid, At least three feet space in front of that, right? If it's hollow, who cares, but like at least three feet in front of that. 

And is there like, that's the minimum. Is there more of an ideal, like four, six, eight feet to get better performance or does it have a diminishing return? 

Merlijn van Veen: no, I mean, I, I know, uh, Magoo at one point he put a cardio configuration on a pallet with a microphone suspended to the corners of the pallet and he just rove the pallet with the stack in real time up to a boundary. to see when stuff collapses or implodes, whatever you want to call it. And basically he came to the same conclusion. 

So he had two pieces of rope keeping the microphone to the corner, right? So distances didn't change. And he just drove the pallet, so I'm told, up to a significant boundary. And, you know, you, you could get as close as one meter, that is one meter between the back of the enclosure and the surface that we're talking about. 

He could bring the pallet with the stack up to within one meter and not see any detrimental outcome in the front, but any, anything less. is, uh, is ill advised. You have been warned. 

Sean Walker: that's that's awesome though. That's super good. You know, not only information, but that it was. A, uh, you know, a test. They did, they did that. And you're like, okay, cool, man. Four feet doesn't help you. Three feet's the number, basically. Like get it three, one meter, three point, whatever, whatever. I don't, I don't do the math either, man. 

Merlijn van Veen: No, that's three feet. You're right. And one, one manufacturer is a little bit more permissive and they, they, they, uh, in their collateral, they say two feet. Uh, but I'd rather earn the side of caution. 

Sean Walker: I mean, but what's one foot, dude? I mean, you know, Oh my God. I wish you guys could see the looks on these people's faces right now. Andy, we got to start doing this as a video. 

Phil Graham: has entered the monologue part of the conversation. 

Andy Leviss: Cool. Well, I mean, that seems we've been going along. We're now well into two episode territory, so we should wrap it up. Sean, you want to send us home? 

Sean Walker: Yep. Thanks for hanging out, guys. Thanks for nerding on subs and letting me talk some nonsense while I'm here home sick and, uh, you know, with the dogs and kids running around in the background. Thanks to Allen and Heath and RCF for, uh, letting us talk some nonsense. And, uh, that's the pod, y'all. 

Music: “Break Free” by Mike Green