BillFitzmaurice.info

TLDR… What do you think the best system is for our situation?


Hi everyone!

Exciting news! We are in the planning stages for the next version of our outdoor sound system at Burning Man, where we play electronic dance music. We hope that we can get this community's help to find the right fit! Here are some details that will hopefully help you help us.



The Venue

Our primary coverage area is about 100' wide by 100' long, centered up and right against our stage/DJ booth. That said, there is no limit to the length of it. We are in a hard, flat, open desert area that goes for miles. For practical purposes, though, let’s just say that the max area for our sweet spot would be 250’ wide by 350’ long.

This system will pretty much run 24/7 for 10 days straight every year. The number of attendees usually varies from 1 (just a DJ, having fun on the decks) to 1,000+. It could be as high as 3,000 (maybe) if we have the right tracks and sound quality to reel 'em in... I mean, when the people hear dirty beatz, they must dance. Moths to a flame and all.

Anyway, It's tough to give any info more exact than that, because everything is so fluid out there. People come and go all the time, some for a few minutes, some for hours. Also, there is a lot of competition! Around the clock!

That said, it is a place where MASSIVE projects happen, and it is the perfect environment for going bigger than we could do anywhere else. So we want to go big! BIG!!!



Previous Experience

Our current system is has cabs designed by Bill Fitzmaurice:

8 x T60-Lab15
6 x Omni Top 2x12s
Crown I-series amps
Dbx PA2
Furman power conditioners

At one point we had 12 x T60s, but after 10 years of service in the dusty desert heat, they are now all due for retirement. If we go the same/similar route for our new build, we definitely want to put as much time and energy into making them as durable and maintenance-free as possible for those conditions. We will poke around on the forums for the latest techniques. We just haven’t got that far yet!

We have tried a few different system configurations over the years. Here is a previous thread that shows some of our evolution… Please, don’t judge us too harshly for the sins of our past!

viewtopic.php?t=23956&hilit=funky+town

In addition to what is shown in the above thread, last year we experimented with two groups of 4 x T60s, stacked 2x2, with 56' separation between. We had 2 x Omni tops on each group of subs, stacked vertically. We used 2 more Omni tops for center fills. This setup allowed the audience direct access from the dance floor to our DJ booth, as compared to previous setups where there was no direct access. We either had the booth lifted off the ground, or the T60s between the booth and the dance floor. Anyway, the direct access was a big hit! …But maybe we took a hit on sound quality with the split stacks… I dunno...

So this time around, we’d like to start with optimal sound quality, and then design the aesthetics around that. Instead of the other way around like we've always done!

To be clear, we followed all the recommended settings since learning our lessons from previous years. These configurations sounded great!

...But we haven't been able to achieve the "warm hug" (we’ll get into that in a bit!) that our fellow sound camps with the big expensive brand name systems have perfected.

Which has us searching for more...



Our Goal

Like everyone else here, we want to produce the best quality experience we can. Regarding sound coverage and quality, there is a completely subjective gold standard that we are hoping to reproduce. (My guess is that there are many eyes rolling right now, so sorry in advance for being a silly goose!)

The gold standard system out there was mounted on one of the bigger vehicles that roams the desert. These are the general specs we could find of the D&B Audiotechnik system they had:

12 x B2 SUBS, 2 x 18" per cab (24 total 18" drivers in 12 dual tapped horn cabs, or maybe bandpass horn cabs? I dunno.)
16 full range tops (8 x V12 and 8 x V8)
All arranged in the big U shape, subs across the bottom, with a line array on each side
DJ Monitors - 2 x 18" subwoofers(V-SUB) with 2 x E-12 and 4 x E-8 full range speakers
70,000 watts total

This system is by far the best we have ever heard out there. Or anywhere for that matter. Once you entered their sound bubble, you were in another world! …or at least a totally different weather pattern! Which is saying a lot, because there are many, many large scale systems out there, all within walking distance!

That's not to say it's just loud, though. It was tuned to perfection. Whether you were right up against the subs, or a quarter mile out (or more), the sound was clean, pleasant, full, etc. Warm sound hugs all around! You could have a normal conversation anywhere in that area, no problem. No ear plugs necessary, either. It's not uncommon for folks to stay out there for up to 12 hours at a time. Then, after an epic night, they wake up the next day feeling great, no tinnitus, and do it all over again! For a week!

Side note. These are folks that really appreciate quality sound, too. Standards are high. There are very few alcohol soaked eardrums who think louder is better out there. After all, if it isn’t to their liking, they simply walk or bike a few minutes to the next massive sound system. Or the next one. Or the next one. And so on.

Our hope is that we can perhaps come close to, match, or maybe... just maybe… beat that gold standard! We'd have to do it by being clever, though... In terms of budget and resources, we are completely outgunned. Completely. Outgunned.

That said, though, we might be able to use Hofmann's Iron Law to our advantage. They have very tight space restrictions - everything has to fit on their vehicle's chassis. Whereas we can spread out and take up much more space than that. So, maybe with the magic of Bill’s horn designs, we can compete with their expensive name brand equipment? For a fraction of the cost? It's an exciting thought!



Our Limits

That said, the first and most practical limit we have is storage and transportation. We have calculated that we can manage up to 24 x T60s with our current setup. Ideally, we won’t need to go beyond that. But if a strong enough case is made, well then we must abide!

Financially, we can make 24 fully powered T60-LAB15s happen. With a little wiggle room for more if needed, or other cabs/equipment. Again, we are but small potatoes out there. Well, tiny potatoes, actually. Perhaps microscopic… Yep, we are single-celled potatoes. Okay?

For power, we can do up to 14,400w with our current power conditioner. We can easily double or even triple that, though. Not a big deal. But obviously, if we can get away using a lower amount of energy, that is ideal. Fewer things to worry about is always nice. And hauling fuel out there is a chore.

For our setup area, it depends. For width, if we need to split up the system, we can easily go 56' wide again to minimize some cancellations. We might be able to go 120' wide or so, but that depends on if we get a larger plot, which is unknown for another couple of months. For height, we can go up to 6' high under the stage if stacking the T60s 2 high makes sense. Preferably we would do only 3' though, enough for one row of T60s. We can go up to 18'-20' in height otherwise for tops. However, we would prefer just stack tops 2 or 3 high on the tubas, and strap them down for ease of setup.

On that note, ease of setup and tear down is very, very important. Here’s the deal. Turns out, there is nothing but desert out there. Nothing. Zip, zero, zilch, nada. Then, a bunch of crazy fun weirdos descend upon that nothingness for a week or so. They labor round the clock to set up a temporary city. And after it’s over, they have to make it all disappear. Or they don’t get to come back next year. This often means crawling around picking up every little iddy biddy thing that wasn’t there to begin with. Leave it like you found it. You know, nothing.

I say all that to make this point - if we don’t have to do extra work, such as digging holes (and then fill them in again) to secure this and that from the nasty windstorms that happen out there… well that is just really, really swell!!!



Other Tidbits

Yes, yes, yes, I can hear it already! Why don’t we just build in stages, and keep tinkering and adding until we arrive at the promised land? Point taken! Obviously, we will only know what works when we can actually tinker with a full system out there. But here’s the rub… Unfortunately, we only get one chance per year to tinker, and it is a long, intense journey to get all the way out there. So this is why we are here now, asking for any insights the community has while we are in the planning stages!

Maybe some fun math would help? Fair warning, the following calculations are probably wrong, because I’m a dummy… So please keep in mind, the purpose is to help select the correct types and numbers of cabs.

In another thread on this forum, CoronaOperator describes a "hug the subwoofer" feeling with his system. And I suppose that’s what we’re looking for. Perhaps others call it “feel it in your chest”, or “soaking up bass”, or “bass massage”, etc. The point is, things are buzzin’ bud! Bzzzzzz

Anyways, he mentioned that the hug starts at 132db at 50hz. I'm guessing this occurs indoors? So maybe he gets some room gain to help get him there, I don't know. But we won't have that advantage, since we are outdoors. So we’d need more power and/or more cabs, correct? Or some sort of miracle. Maybe if we pray to Tom Cruise…

Here’s the thread that discusses the “hug”:

viewtopic.php?t=25097&start=30

So… 132db at 50hz…

According to Bill's chart, 1 x T60-LAB15 produces 101db at 50hz. (I assume this is the 1w/1m measurement?)

31db+ to go!

From what we could find online, in theory we gain 3db every time we double the power to the driver, and another 3 db every time we double the number of cabs...

So, taking our setup last year...

We had 8 cabs, (1-2, 2-4, 4-8), that means an extra 3 x 3db for 9db. So at 1w per cab, we are now at 101db + 9db = 110db.

22db+ to go!

For power, if I remember correctly, we ran them at 50v, 8 ohms, so that would mean 50v = I*8. I = 50/8. W = V*I. So 50*50/8 = 312.5w per cab, correct? So that would be a little more than 8 doublings, correct? 1-2, 2-4, 4-8, 8-16, 16-32, 32-64, 64-128, 128-256... for 8 x 3db = 24db or so.

Is that anywhere near the correct line of thinking? Listen. I have no idea what I'm doing here. Maybe there is a difference in impedance at 50hz than 8 ohms, or something(s) else that I have missed? Probably yes. Probably 99.9% chance I'm wrong. For a number of reasons I’m sure.

Well, until I am shown the light, and for the sake of finishing this train of thought, I'll just assume I didn't mess it up too bad. (Please show me the light, though!)

So...

110db + 24db = 134db

134db > 132db…

Awesome!!!

So in theory, we should have reached the threshold of CoronaOperator’s hug...

And maybe we did get all huggy and stuff...

But here's the thing…

Compared to that D&B system's "hug", we were nowhere close. Don't get me wrong, we sounded really, really good. The best that a radio station audio tech could get it to sound with all the recommendations from the plans and from this forum. But compared to that other system, we are definitely not there yet… Doh!!!



The Ask

Please help! This is probably the last chance we are going to get at doing a large DIY system for our camp. Having a blank canvas to fill is both an exciting and daunting task... Bottom line, we are open to any suggestions, insights, insults, etc.

So…

What would you do?!!!

For instance, maybe the T60s aren't the best fit? Considering the storage and transport limit, maybe smaller Tubas, or Titans would be better? As many that would fit in the same space as 24 x T60s? And maybe then we could experiment with end-fires to keep the stage a little quieter? How would you place and stack speakers, assuming sound quality comes first, then aesthetics second? What would you have in your rack? Etc. All the things!

We are really looking forward to comparing and contrasting as many ideas as possible. Can’t wait for all the fun and knowledge dropping to come!

Finally, time is a bit of a factor… This will be a big project for sure, so we’ll need plenty of time to crush it all out. We hope to start cranking at the shop in a month or two…After all, August will be here before we know it!

161 days and counting!

Thanks in advance!!!

EPIC!! Wow Levi, you've set yourselves quite a goal, they'll all see what the tiny potatoes are capable of!!
Just quickly first, have you had a chance to read this?
https://billfitzmaurice.info/forum/viewtopic.php?t=358
And this?
https://billfitzmaurice.info/forum/viewtopic.php?t=1293

16 T60 will get 135dB flat to 28Hz. Using 24 cabs you could set them up for cardioid operation, there's plenty of information on the web how to do that. Ever heard the Dancetronauts system? They have T60s and DR280s. That's what I suggest. Since you don't really want super wide coverage with the subs I'd place them side by side, not split.

First off, you can absolutely get the sound you're looking for without having to resort to high priced commercially produced cabs and you're in the right place to make that happen.

The DR280's are a great choice and given the environment they'll be used in, I'd 100% choose the sealed/non ported option to keep playa dust out of the rear motor structure of the drivers. Three to four cabs per side would allow you to power shade them, reducing the volume on the lower cabs in a "J" array for people that are up close and increasing the volume at the top of the array for increased coverage at distance. Get them up on scaffolding or construct platforms for them to be stacked on that put the lowest cab a few feet above dancefloor head level.

Personally, for recorded content outdoors, I would consider Titan 48 to be the only logical solution. Even though the Tuba 60 will play slightly lower, you'll never achieve it at sufficient volume outdoors and the Titan 48 is massively more sensitive in the ranges that can be reliably reproduced outdoors. Even if some of your content is below the 35Hz highpass filter used for a Titan 48, those frequencies will still be fairly well represented, they don't disappear just because they're on the down side of the cutoff frequency. The vast majority of EDM basslines are over 40Hz, some occasional 30-40Hz, and on rare rare rare occasion below 30Hz. Out of 1000 EDM songs, my educated guess is that 2% have substantial content below 40Hz and 1% below 35Hz. Out of 1000 people in the audience, no one (okay, maybe one) would ever sense anything missing between the T60 and T48... Except the T48 will make more usable SPL on the same power, require less power to make the same SPL as the same number of T60's, and/or make the same usable output with fewer cabs.

To make your system twice as loud (+/-10dB) as what it currently is with eight T60's, it would take Fifteen T48's on 6750 combined Watts... or Twenty-four T60's (15" loaded) on 14,400 combined watts, 40Hz and above.

To match twenty-four full width 15" loaded T60's on 600 watts per cab, 14,400 total sub system power, twenty-four full width T48's would only require 180 Watts per cab (not a typo, 180), 4300 total sub system power. 10,100 fewer watts needed for the T48 option to match the same output potential as the T60 option over 40Hz, where it really counts.

If you don't mind the weight, which I doubt you do being as you're already using a heavy driver, you can load the T48 with PRV Audio 15SW2000 drivers, which offer slightly more power handling and more importantly, slightly increased sensitivity and extension in the T48 compared to the Eminence 3015LF. AND... they're only $190 compared to $335 for the LAB15 in a T60. At 24 cabs, that's a driver cost of $4560 for the T48 which is almost half of the $8040 it would cost to outfit twenty-four T60's. You might even be able to get a reduced cost based on your fairly large quantity... maybe.

As always, make them the full 36" width if there's any possible way to transport and store that size cab. Otherwise, build as wide as you possibly can and don't take this advice lightly, it would take two 24" T48's to match the output potential of one 36" T48 at 40Hz. Every inch counts. Go big or go home.

One downside of the T48 option is that optimum deployment may not fit your vision or allotted space. I would recommend trying a few configurations to test and see which give you the coverage that best meet's your requirements. I'd personally start with them lined up in a row and tilted 45° forward, effectively ground loading the whole array which extends the horn length and slightly increases the mouth area for increased extension and sensitivity where you need it the most, down low.

T60 and T48 in those numbers have the same sensitivity, as both have reached the efficiency limit, while T60 still goes lower. That being the case neither benefit from any effort at additional boundary loading, unless there's a twenty foot high wall you can use.

Hey Levi, I sent you a PM.

Bill Fitzmaurice wrote: ↑Mon Mar 11, 2024 1:34 pm T60 and T48 in those numbers have the same sensitivity, as both have reached the efficiency limit, while T60 still goes lower. That being the case neither benefit from any effort at additional boundary loading, unless there's a twenty foot high wall you can use.

Can you expand on that a little bit? Based on traditional calculations the 40Hz sensitivity of 97dB for the T60 and 102 for the T48 would typically mean it takes almost two T60's and twice the power to match the output of one T48. At what point is the "efficiency limit" reached for each cab design? How many T60's to reach the efficiency limit? How many T48's?

The efficiency limit is when you've got all you can get. If you could keep getting 6dB additional sensitivity with each doubling of cab count eventually you'd not only reach 100% power conversion efficiency, you'd exceed it. The finite efficiency limit with low frequency horns is around 50%, with direct radiators around 25%. Traditional calcs don't account for this, because they only apply to a few cabs. The limit is also reached at the upper end of the pass band well before it is in the lower end, because it starts off with higher efficiency in the upper end. T48 and T60 both reach the limit all the way to Fh at 12 cabs. Since the T48 starts off with higher sensitivity it also starts off with higher efficiency. That means it reaches the limit at the upper end sooner than the T60. T60 sensitivity equals the T48 at four cabs.

Thanks for the explanation Bill. I'm not sure I clearly understand yet. I'm gonna let that marinate for the night.

View it with HornResp. Model a sub, then use the multiple speakers tool to see what happens as you add more drivers. Keep the impedance constant by adding the same number of parallel and series. Sensitivity will go up, but by more in the low end, eventually reaching a point where it's flat all the way down, where adding more doesn't give any sensitivity increase. You can see the efficiency go up as well with that tool for the increased number of cabs, but by less and less as more cabs are added. Maximum output will continue to go up by 6dB with each doubling of cab count, but once you reach the sensitivity/efficiency limit it's all from power, which must be increased fourfold for each 6dB increase.

Bill Fitzmaurice wrote: ↑Mon Mar 11, 2024 9:21 pm Maximum output will continue to go up by 6dB with each doubling of cab count, but once you reach the sensitivity/efficiency limit it's all from power, which must be increased fourfold for each 6dB increase.

Could Efficiency Limit be similar to how much horsepower needed in a car to go faster, when you're already going really fast? Is it exponential like wind resistance?

It's more like terminal velocity of a falling object, which is caused by wind resistance. Another way to visualize it is a given speaker or group of speakers is limited to a maximum electrical power to acoustical power efficiency. Say it's 50%. You can get that with one perfect horn. The reason we don't do that is the size is impractical. You can get it with a grouping of smaller horns as well. How many depends on their individual efficiencies. For instance, the efficiency of a single T60 at 28Hz is around 10%. To get to the 50% maximum you need at least five of them.

Wow!!! Thanks everyone so much for the responses! This is great!!!


@Keryn

Thanks for the links! This forum has so many topics with so many gold nuggets buried within... It can be easy to miss stuff like this!

We will definitely up our game when arranging the tops. Vertical arrays all day!



@Bill

The King himself! Thanks for responding so quickly!

No, I never did hear the Dancetronauts’ art car. I saw them from afar in the midst of the sea of epicness out there a while back, but never actually made it to one of their parties. And now, it turns out that I missed my chance. In 2015 they were a little naughty and got booted. Apparently they had a sizable system, though. As I understand it, they’d basically roll up to a party and then just blast the system. Which is a funny troll, but doing it at the actual Man Burn was a step too far from the looks of it. Do you have any idea what type and how many T60s they had? How many DR280s?

Any reason why the DR280s would be better than the OmniTops for this situation? Would the DR280 90 degree dispersion compression horn array version be best (because of the desert dust)? Or the piezo version? We’ve noticed the piezo sound quality degrades in this dusty environment over time.

Thanks! We will definitely plan on one row of T60s side by side, instead of splitting them up.

So, if we had 16 tubas, would it be optimal to do one row of 14 side by side, with the remaining 2 stacked one on each end? Then the DR280s stacked vertically on top of that? For a big elongated U shape?

Or would it be better to do two rows of 8, with the tops vertically on each side? For a little fat bottom U shape?

As for boundary loading, we do not have a 20' wall we can use. We have a couple of 20x8x8 shipping containers, but I’m guessing those won’t be nearly enough, or sound that good since they will be mostly empty.

Also, what is Fh? Frequency high?

If we can get 135db flat to 28Hz with 16 x T60-LAB15s, what does that mean exactly? From what top level does it start to get and stay flat? Does that mean 135db at 50Hz as well? Or would it be higher, maybe 140db?



@Seth

Go big or go home? We definitely want to go big! No way we’re going home! Well, not until the week is over anyway.

Great point about a sealed option for the DR280s! And at least 3 on each side, sounds good! Do you think there would be any downsides to just strapping them down on top of the subs? I know you said the bottom one should be just above head level, but if we shade them properly, do you think it would be just as acceptable to stack them on top of 2 x T60s? So about 5’ off the ground for the bottom DR280? Like we did here, but with the 2 corner pieces on top, so they are 3 high:

viewtopic.php?t=23956&hilit=funky+town&start=15

Also, that is a very interesting point about the T48s having increased sensitivity above 40Hz. Maybe it is worth giving up that low low end for a bit more low end…

Which brings me to my next question…



@Bill

But if we are talking about doing 4+ x T60s, then does that benefit/tradeoff disappear? So the T60 is the best way to go if we are talking 16+? Because we get all the sensitivity of the Titans in that 40-60Hz range, in addition to the lower extension of the Tubas? And this holds true no matter how many Titans we have, even if they significantly outnumber a set amount of Tubas? Is that what you meant?

Or, to put it another way, if we have something bonkers like 32 x T48s, is that not any better than 16 x T60s? I guess that assumes the same amount of power going through them, and all other things held constant… But what if we have twice the power as well? Or does that matter at all? Oh no… I think I just got cross-eyed…

That said, as long as we are comparing subs, that brings me to a bit of a tangent…



@Everyone out there…

As I mentioned in the original post, we are going up against the gold standard, which happens to be a D&B system…

The chart in their manual shows that for one 2x18 B-2 cab, the peak of its output is between 40 and 60Hz (it’s relatively flat there), with a “max SPL” spec of 139 db…

“Max. sound pressure (1m, full space) 139 dB / 136 dB, (SPLmax peak, test signal pink noise with crest factor 4)

The chart is “normalized” I think, so it shows a level of “0” at 40 - 60Hz, instead of the actual readings like on Bill’s charts. Basically, it’s a parabola that starts at -30 at 20Hz, peaks at 0 at 50Hz, and then drops back down to -30 at 180Hz or so. The chart is on page 7 of the manual, available to download here:

https://www.dbaudio.com/global/en/produ ... -downloads

What does this mean, exactly? What is max SPL? Is it just like it sounds? The absolute highest decibel level at whichever frequency(ies) a speaker can reproduce, before it done get all blowed up? So in this case, would it mean that the B-2 gets 139db at 50Hz-ish when they are running at max power indoors? Which the manual says is 600W RMS / 2400W peak 10ms. Nominal impedance 4 ohms.

So that we can compare apples to apples, do we know what a “max SPL” of a T60-LAB15 is? Or does that even matter? I don’t know…


…But here’s what I do know! The Death Star is fast approaching… Bill, how do we destroy it with your designs?!

If they have 12 of the B-2s, with max SPL of 139/136 db at let’s say 50 Hz for one cab…

Then for 12 cabs, they might get an additional 3.5 x 6 db = 21 db…?

So 139 + 21 = 160/157 db in that range? Whoa…

Call me crazy, but I think that seems like it might be enough energy to destroy an entire planet in one shot!!! The Death Star…

I gotta be missing something here, right? Is there an efficiency limit that would have been hit way before 160db? Again, I think the B-2s are bandpass horns… So are they dealing with the same ~50% horn limit? Or would it be more at the direct radiator limit? Does that matter?

One B-2 cab is about 46”x23”x36” exterior dimensions and weighs 225lbs, versus one T60-LAB15 being 60”x27”x30” and about 185lbs, if that matters… Also, I think the B-2s have an “Infra” mode that increases the level in the 50-60Hz range by a few more decibels, if that matters...

I don’t know. I’m out of my depth here.

But if I may, when I step back and think on a basic level, it just seems like they have way more driver surface area that can move way more air. Or, I guess to be more accurate, they transfer way more energy into the air. But it costs them way more power to do it. If we are able to put as much energy into the air as they do, but we use bigger cabs and smaller drivers to do it with less power, is that ultimately how we even things up? Or is this whole line of thinking overly simplistic and just plain dumb-stupid-wrong?

Are their cab designs somehow “better” in certain ways? Are they somehow designed to sacrifice all frequencies above 180Hz to get more in the 40 - 60Hz range? I don’t know, are they perfectly smooth and curvy on the inside, versus angled and blocky? Are they like some super fancy and expensive hand-crafted cello vs. a cheaper mass-produced one? Or does this all fall into the eye of the beholder category? Maybe only the finest ear would even be able to tell the difference?

All I know is that when you stand in their sweet spot vs ours, it’s a big difference. Does that just mean they are 10, 20, 30+ decibels higher in the 50-60Hz (or lower) range? Silly question, because probably no one has been out on their dance floor, but when you compare different systems that you have experienced in your own life, do you think that is the main difference between higher and lower quality systems? Just having the right decibels levels at the right frequencies? Or is there something(s) more to it?

Power Update

We have decided that we will get an additional power conditioner, so 28,800 total watts will be readily available. We’ll use a little of that to cool the amps, and for lighting and other knick knacks. We figure it’s better to have the headroom given the high temperatures out there. No need to double up any amps on a single circuit and risk a sudden stoppage of dirty beatz.

I don't know what the exact B2 design is, but all horns are bandpass. Their figures are fake, though, as they use peak. Engineers don't use peak. Marketing departments do. I can say for sure that they can't get the most from two 18s from a cabinet of that size. It's even too small to even get the most out of one 18. It's not that much larger than a T45 loaded with two 12s, so the horn is going to be too short.
The DR280 is more sensitive and goes lower than the OTop 12, or the OTop 15 for that matter. Compression HF drivers with 1.2kHz crossover will better handle long throw outdoors.
Dancetronauts was tossed from Burning Man because they were too loud. They took that as a badge of honor, and since they did it with DR280s and T60s so do I.