BillFitzmaurice.info

Aaand the journey continues, now we are nearing us the low end :)
Will need to rearrange some things in the shop (and clean it deeply…) to be able to do 4 at once first, will do that as soon as the weather lets me.

I have a friend with a wall-saw where i will do the rough cutting oft he panels to have it a bit more handy in here.

The thoughtprocess is a bit extensive in my mind, but it led me tot he way oft he T30. Going for dual 12“, 30“ wide. Wired in series inside, one input one output socket to have them parallel. Going to be the low end oft he freshly built DRs, 8 cabs in stacks of four for the beginning.
Will go with a 4p-wire to the stack, split it to two 2p wires and then go for each cab. The amp allows up to 4 cabs per channel, will try to not drive this to limits…rather two per channel or when doing 12 in total 3 per channel.

Usecase is outdoors, no live band application and rather experimental subgenres from DnB/psy/Breakcore…

I tried calculating around if a longer horn would be of any benefit, but came to the point it is not worth it for me. So I will go for the plate in the plans.

Some further thoughts on that, that hopefully will be critisized:

I’d go for the cut corners, to have the panels shorter and for the handling when stacking them. On the other hand, the cutout-handles would be nice in both back corners. Not sure yet. Cutting the Corners and placing a sunken in handle there would be an option maybe?

Still not sure how/where to place the input socket then. Maybe a sunken in Variant, that fullfills the bracing in the same time? Would it be faulty to take some volume out oft he horn path between the back panel and the chamber? I do not want them visible, so it has to go in the back.
Or not cutting the corners, doing the cutout-handles on the sides and cut out a part in the middle to have the connector going in from the side oft he cutout?

I tend to go for wheels, either 4 on every cab or just every second cab and clamping always two together for transport. But not in the corners, in the „back“-surface looking from the mouth to have them stacked in two rollable like a rack (30 by 30 by 60 inches then). As they will never be used single, the pairs should work and need half the wheels.

Plan to have stacks of at least 4, including the V-Plate. My mind wants to use the V-Plate as a stand for the DRs, so i thought of having structural parts on top of the plate to stiffen that, that would have the grooves already to take the lower DR in the correct angle. Stacking two DRs on Top of each T30-Stack. Would also give me a reproduceable distance between tops and subs for a fixed delay setting between them. Depending on the venue size, i would then take stacks of 6 to get higher, or have the height difference upwards by having it in the structural parts higher. Would be about 15 cm or around 6 inches to compensate when a stack of 4 sits on pallets, to get the bottom DR on a height above 180 cm (around 71 inches or whatever this means in feet)
(Other optional usecase would be to stack just two T30 vertical and one DR on top; there would be another clamping solution for that DR then. In case something smaller is going to happen with lower needs)

The Plating is always only done with a top-plate; the bottom end is just the floor as far as i found examples of that. I tend to place a stack on pallets to get off the dirt below, and thought maybe a bottom plate there would be better? Anyone experiences on that?

Assuming a top and bottom plate beeing there, i thought about extending a 2 by 4 or something similar all the way til the back, til the cut corners to connect top and bottom in the back oft he stack. In the Front, I’d connect the top and bottom plate on the outer corners, so the plate and the stack is fixed together in one rush. I also thought about combining bottom plate and pallet below to one fixed instance, to have it altogether always the same.

Here a little sketch to that thoughts:
red bars horizontal would be the ground support for the DR. DR is the red scattered area to scale.
Red bars vertical would be the connection front/back, clamped/strapped together top to bottom in each end. Additional strapping top to bottom in the middle part where the cabs touch (red circles)
The blue frame is the pallet size, i noticed even one could be enough. Would attach the bottom V-Plate fixed without overlap, so the T30 can sit on the pallet meeting the plate flush. Weight should not be an issue, as it sits kind of balanced...maybe strapping the whole thing to the ground somehow; especially when going for a stack of more than four.

Sooo...any thoughts to these points?

Edit: Gnah, forgot one point:
I printed the side-panel to scale, and want to do a routing template to not draw the panel outlines every time. Now, when printing the 3d-model to scale, the panel width is around 14mm. Should i go for the lines a s in the plans, and take them as a fixed value and do the width from there? Or should i go for the center of the lines in the model?
Want to do 2mm grove in the sides to place the panels in there. Anything on that?

Good day Marflinger, I wished to return the favor of how helpful you've been to me, but I don't have a lot to add.

1. I lay subwoofers on an industrial carpet. That lets me make fine adjustment because they slide relatively easily.

2. The T30 plans have an option to reduce the back chamber. From other posts, and the T48 plans, this slightly reduces the response below 40Hz and increases the response above 40Hz. I'm guessing the frequency (40Hz) will be different for a T30, but the overall effect the same. This monster thread has great information. I don't think such a slight change in volume would have a measurable / audible effect.

3. I like all the handles I can get, even with the extra weight.

4. I like two single-driver speakers instead of one dual-driver speaker. When I'm moving literal ton(s) of equipment, smaller loads are far more maneuverable, and require less strain. The difference in cost is pretty small in my opinion. (Because of this, I've never built a dual-driver speaker, when a single-driver option exists).

5. I do NOT like wheels per speaker. I use a hand-truck or dolly to move heavy loads. If it's heavy enough to need mechanical advantage to move, then I like the protection of a hand-truck as I "bump" it up or down stairs or on/off trailers. Plus casters are outrageously expensive and finicky when I need them. Often I have to move over grass or "rough" terrain so casters don't help, but pneumatic tires do.

6. I can't quite tell from your plans if you should use centers or not. I find using existing parts / cuts as a template far easier, faster, and more precise than plans.

Best!

Just a light recommendation that I hope lands heavy... you've put a lot of time and effort into your research, more than most, and I am enjoying you whole process immensely. Since this is going to be such an epic system, I highly suggest you take your research to the next level and build 4 temporary test cabs out of the least expensive ply first, two Tuba's, two Titans, and test prior to making your final cab design determination. Throw them together quickly with the ugliest construction grade ply you can find. Tune them, listen to them, test them, load them in and out of your transport a few times, roll them around the block, stack them... then commit and build the design you choose and never have to wonder if you made the right choice. Toss the test cabs in the garbage or cut them down and put them in the scrap ply pile.

Eight cabs is a large commitment to make and leave anything on the table. Plus, it would make a good read. I enjoy your posts and being witness to your journey. No sweat if you choose to forego the advice. If you just want Tuba's because you want Tuba's... there's really no getting around that. But, if you want the best possible system, test and see.

Plan to put your DR's on poles or design your plywood mount to get the bottom cab 213cm or more above the ground. More is better.

If you put the subs on pallets, put ply on the top pallet or use a bottom v-plate for optimum results.

Yay, thank you both for your thoughts :)

Soo, one to the next:

mtglass wrote: ↑Sat Feb 14, 2026 7:58 am 1. I lay subwoofers on an industrial carpet

Not an option outside in the forest (at least for me); need to level the ground and the dirt would be a mess. the bottom will sure be somehow liftet; pallets are already made so why not this.

mtglass wrote: ↑Sat Feb 14, 2026 7:58 am This monster thread has great information. I don't think such a slight change in volume[]

Nice, didn't see that thread before (or forgot again) Thank you :)
Yes the chamber reducing is in the plans; the driver i want to use (LaVoce SSF122.50L iirc) does not need that reduction. My point of Volume change is in the horn path, between the backpanel and the driver chamber, to have an option of sunken in connectors there (as i did on the DRs, here: download/file.php?id=19843&mode=view )
So to say instead of the lost volume by the bracing, i will have a link to the outside that does the bracing as well as holding the connector.

mtglass wrote: ↑Sat Feb 14, 2026 7:58 am 4. I like two single-driver speakers instead of one dual-driver speaker.

Well yeah i get that, but i want/need them wired in series; this is sure to happen, longer way led to this (see the thread t30/48/60...) but i will go for the dual driver.

mtglass wrote: ↑Sat Feb 14, 2026 7:58 am Often I have to move over grass or "rough" terrain so casters don't help, but pneumatic tires do.

Me as well, the last part will always be lifted by hand as the area usually never has any rollable way. I like casters for the rest of the way, moving them around at home, moving them to the car, on the car and so on...talking about bluewheels like on a amprack, not the corner casters in the plans. But i think on the parts of the way i will use them, 4 wheels on one cab will do the trick for a pair. so only half the wheels :)

mtglass wrote: ↑Sat Feb 14, 2026 7:58 am 6. I can't quite tell from your plans if you should use centers or not.

I think i'll go for the lines in the plans that are referenced there, and then take the width from there. This would be the result as intendended/designed i think.

Seth wrote: ↑Sat Feb 14, 2026 9:26 am build 4 temporary test cabs out of the least expensive ply first, two Tuba's, two Titans

hrhr, well yes...somebody here mentioned our minds have some similarities...yeah i had that thought as well about testing both :D
I get the favour you have for the titan, but i took all my thoughts (and yours and others) together and landed on my tuba point of listening.
Even if i totally fcked up the simulation comparison, the tuba will be the one that goes smoother below 30Hz. and the volume i need per cab is still just the half...i will just add more T30 when i notice i miss something.
The point of building test cabs would be valid with four each...and this is too much hassle for me. especially as it has to be glued, i can not really reuse the material. it would be interesting, but way to much time and material lost.
Also, I'd assume the difference would be very minimal when both are dual 12" with the same drivers...
But i get your thought, i had that in my mind. But tuba is locked (for now).
I rather thought i'd be interested in meeting any other rigs with t48s playing, and see how that compares. Not sure how many in europe are around, maybe i get lucky one day :)

Seth wrote: ↑Sat Feb 14, 2026 9:26 am If you just want Tuba's because you want Tuba's... there's really no getting around that. But, if you want the best possible system, test and see.

I came to the conclusion, the tuba way of life is the (for me) best possible system i can achive within my limits. Maybe, when the rig is complete and i got some spare time handy, i could do 4 T48s and compare them (including measuring of course). But as time is not that endless sadly, i want to have it with 8 T30 first. So sorry...in case that changes, you will get a notice as the first!

Seth wrote: ↑Sat Feb 14, 2026 9:26 am 213cm or more above the ground. More is better.

Yeah not sure about the total height right now. With my plan for the top V-plate, i could also just lift it to whatever height. On the other hand, in case i end up at 6 T30 per side, the height is already done.
The seperation from the subs is really a "i do not want this" point for me with the seperated stands or whatever...as long as this doesn't kill something important, i will need to find a way for that...but this is a problem i can solve later as well.

Seth wrote: ↑Sat Feb 14, 2026 9:26 am If you put the subs on pallets, put ply on the top pallet or use a bottom v-plate for optimum results.

Aight yeah, as i thought. Will do that, probably as mentioned botoom v-plate w/o overlap so the T30 slips into its place as it is fixed there.

Well yeah, thank you again. i cleaned the shop a bit today, but i need better weather to get an annoying machine out of there; the space it takes is highly needed....

I will do some details on the corner handle/input/bracing-combination to have other eyes seeing my thoughts before i break something, but this could be a smooth solution i think. we'll see, i keep you updated as soon as i got further :)
The amp is on its way, for the drivers i am right now arguing about a quota for takeing 16 of them at once; last year they were cheaper for a while, would love to get that old price imported into this year :D but i am on it :)

Marflinger wrote: ↑Sat Feb 14, 2026 11:34 am ... below 30Hz. and the volume i need per cab is still just the half

I completely honor your choice. But, I'll just add this last piece for you to consider. Looking at response graphs for subs in an attempt to figure out how many cabs are required, the only part I take into account is what the SPL is at the lowest frequency I want to produce. I know we talked about equal loudness contours in the previous thread. Once your system is EQ'd, every frequency above your bottom frequency will be attenuated, in your case probably as much as 20-25dB below the signal level needed to create 30Hz content at an appropriate level. This also means your mains frequency range will also be roughly 20-25dB below your bottom subwoofer frequency.

What happens is, maybe 5% of EDM songs have content below 40Hz (maybe more, maybe less), the listening volume at the average listening distance for all the frequencies the mains produce at a comfortable but responsibly loud level, will peg your limiter when those songs with lower content play. If you're at 110dB 75 feet out on the mains and a 30Hz note plays, you just wont have enough system, even with 6 per side. Matter of fact you'd be better off putting all 8 in one stack, but you still won't have enough system. So, you'll either have to not play the system at the volumes you'll want, raise the highpass frequency, EQ the bottom less than optimal, or let the limiter do it for you (don't do that intentionally). In any case, I don't think you're going to get the performance you have pictured in your mind. It'll still be a great system, I just don't think it'll do what you think it will do... unless your objective has already taken into account that just having some capability down there is enough. I fear it's a larger trade off than you realize. (for the casual reader, this is specific to outdoor venues) Or, who knows, maybe you'll be ticked pink. (as I write out that phrase, it crossed my mind that, now-a-days maybe it doesn't what it used to mean. Hmm)

That's all I'm going to say in the matter. I don't want to be right. I just want you to have the info to make your own informed decision. And again, I completely honor your choice and look forward to it all unfolding... anxiously.

I hope you're able to score that bulk deal on the drivers. That would be sweet!

Well yeah, we've had that before. But lets sort this out:

Seth wrote: ↑Sat Feb 14, 2026 7:31 pm the only part I take into account is what the SPL is at the lowest frequency I want to produce

This is where we differ.
Regarding the sensitivity and maxSPL; the part i consider is the Hz-Position of the roll off down below. And this is where the T30 rolls off lower. No matter if you look at my simulation or the spl tool here.

Seth wrote: ↑Sat Feb 14, 2026 7:31 pm and the volume i need per cab is still just the half

Just to clarify, i meant cubic feet volume, in terms of storage space. T30 close to half the size of a T48, not volume in terms of power/amp/SPL.

You tend to span a metric to measure performance on, somewhere between

Seth wrote: ↑Sat Feb 14, 2026 7:31 pm 30Hz content at an appropriate level

and

Seth wrote: ↑Sat Feb 14, 2026 7:31 pm just having some capability down there is enough.

At first the parts which rely on at least some data we both love:

The rolloff of the T30 sits lower than the T48. The total output is extremly close to each other from 30 to 40 Hz, when comparing stacks to each other with the same drivers. Especially when considering 4 T48 to 8 T30; double the amount of drivers and so on, but this is a part for me in terms of the total size.

Now the dataless points driven by feelings and ideas:
Your point always heavily relies on the spreading over distance. I would limit the system to not create ear damages when smb is close to the front, and whatever comes in the back is what they get there. If they want more pressure they can walk further to the front. The equal spreading over distance in terms of a "reasonable spl everywhere" is no point i consider. The limit of ear damages is way below that; 150db spl in the front are is in the area of damages.
Another part you miss in that process is that sound pressure loss over distance is as everything in sound frequency depending. So lower Hz loose less energy than higher Hz (Absorption by the air as we are not in a vacuum); which is why we have long throw tops in large venues but (close to) never sub-delay-lines or long-throw lowend. Pressure vs intensity is an interesting point for you maybe.
But, my point is rather the perspective of not breaking people in the front; not about going to supply whatever i think is reasonable in the back. The lower spl in the back is accepted, yes even intended. If you want to get a massage of your intestines, you have to get to the front :)

In case you want to dig this further, lets do this in the other thread to have it somewhat sorted.
But the point of the frequency viewed hast to be considered as well as the sound pressure vs the sound intensity. Sengpiel has a lot about that in case you are curious. Phon and sone also a matter to be considered, in terms of your point about perception of loudness vs the loudness level.

Seth wrote: ↑Sat Feb 14, 2026 7:31 pm maybe 5% of EDM songs have content below 40Hz

Todays mastering aspect shifts that downwards, but i get your point. And i know about that low-end-region; but on the same point i know the music i usually listen to, and there is content...but this is only valid in some special fields, totally correct.

Seth wrote: ↑Sat Feb 14, 2026 7:31 pm I fear it's a larger trade off than you realize.

I think we both locked ourselves to some metrics we consider to be the ones to focus on. We ended up in different metrics; but i like my metrics more as you do yours. Which is totally fine; no set of metrics is universally applyable. But i did put a lot of thoughts into the decision, and i don't think i will run into an error on that.

We both have the error of hypothetical thoughts in way too many aspects. I assume you never heard a direct comparison of stacks of 4/8 whatever T30/T48, and me neither. Esp with the same drivers in it, this would be the point to compare. I would love to, but here are none i would be aware of. I will build the comparison if i get time for this; curious enough. But not sure when this bonus time will arrive in my pocket...

And as in the other thread; it is really not a question of good or bad; just a question of which colour of good. So i have no fears of doing something that will not make me happy, don't worry about that :)

Very well spoken. Respect.

Marflinger wrote: ↑Sat Feb 14, 2026 10:47 pm I think we both locked ourselves to some metrics we consider to be the ones to focus on. We ended up in different metrics; but i like my metrics more as you do yours. Which is totally fine; no set of metrics is universally applyable. But i did put a lot of thoughts into the decision, and i don't think i will run into an error on that.

10 years ago (maybe 15 at this point) I was entirely of the same thought and value process you're in now and I had the same arguments/points. I deeply resonate with where you're coming from. Since we're so alike, I kinda already knew writing about it wasn't going to sway you. Absolutely no hard feelings and I'm onboard. Perhaps you'll have a different experience than I have and I'd like nothing more.

No need to continue this line of conversation elsewhere. I'm complete.

Let's do this!

My thoughts about handles is to put the hand-holds in ALL the possible corners. With a 30" cab, I am thinking that 3 handles per corner would be a good option. On my T39s, there is one corner that don't have the hand holds, and I miss them. It causes me to think how I might have to lift them in some certain situations.

I put two Speakons on the back, and two more Speakons in the horn, so that I have options where to plug in and not have the cable show. The only part that stands out is the metal tang in the connector. Otherwise, I don't consider the connectors to be all that visible.

In that size the handle to all corners seems legit, the more i think about it...
Just the front bottom corner, also when hauling the DRs around i noticed i can just grab in the horn; i think there i will let it go without handle. In case i miss it there, the best place to slit it in there afterwards.

Yeah not sure about the connectors in the front, something irritates me on that. Maybe it is just my imagination, i will see how it feels when the first is done and i stand in front of it.

To the stacking part, i tried to visualize my thoughts for a better imagination:
This would be everything to scale, including the humanoid, the two (i guess) most probable variants of 4stack/6stack.
6 Stack already quite high, not sure about that. The blue in the bottom represents the pallet, the red the attached V-plate to that pallet.
In this case DRs pretty high, better for ear damage but not sure if the front is covered enough then.
In this case slightly too low, the height variable as i can just increase the height of the structure on top of the V-plate.

Will do a sketch about the handles and connectors next and edit in in here to not spam around.

Here it is, to the connector/handle:
Stopped the thought about inside the hornpath as a bracing; to have the connector handleable somehow comfy, it would need to be huge.
But i would go for the back corner; in the standard orientation the corner between backpanel and toppanel (Or the Corner from back to bottom, shorter cable paths outside)
Cut the corner only in the middle (around 20 cm for comfy handling); and in the "inside" panels that face each other the sunken in connector (red).
The remaining parts (blue) of the corner would get the handling cutouts. I think with this the handling should work well, and the connector should sit without any extension beyond the outer borders of the cab. Any errors on that? Inside there is then just the cable to the chamber; from this corner the way is quite short (also the intended corner for connectors in the model)

Just for the giggles, the monitoring stack or whatever the usecase will be, just one DR and two T30 per side in comparison:

Marflinger wrote: ↑Sun Feb 15, 2026 1:53 am ...In this case DRs pretty high, better for ear damage but not sure if the front is covered enough then.

Plenty of coverage up front with that elevation. You definitely don't want the speakers at or below head level. Give it a try. Put your DR up on something and give it a listen. Or just put it on the bench and lay on the floor. Yes, directly below the mouth, you'll hear some high frequency attenuation if you listen for it. Testing this indoors will not be as apparent. But, it's attenuation, not elimination. It's actually a good thing for people up that close. Plus, the general population won't be aware of it, they're busy having a good time. Matter of fact, 99.99% of them will never hear the things we do, they don't know what to listen for, even if they were trying to listen for it. And really, every listening position will have a slightly different sonic signature. You can tune the system based on one listening position or the average of many, but the variance across all listening positions still exists and you can hear it. There's no getting around it. Getting the speakers up benefits everyone.

However, as far as coverage goes, those stacks are going to have to be separated by about 20-22 meters, putting them 10-11 meters left and right of center stage. If you're really intent on the front and center coverage, you may consider canting the stacks slightly inward or adding some center fill. SLA Pro's would be a good choice here. Limited visual impact near the stage/booth and additional coverage up front and center.

Seth wrote: ↑Sun Feb 15, 2026 10:33 am Testing this indoors will not be as apparent.

Funny part, did this an hour ago. Stacked both ontop of each other on the amprack and turtled around close to it below. Even indoors it works somehow way better than i expected.

I will test with the 4stack how high i can lift them up and build the ground support for 4 t30 respectively. By this i will see if the height of 6 t30 will be still good enough.

Seth wrote: ↑Sun Feb 15, 2026 10:33 am20-22 meters

Intending to cross at around 100 hz, which would equal to a distance of around 18 meters. (56 feet) But yes, well aware of that aspect; bill told me in the beginning.
No frontfill intended, toed in will be the way to go. Stage is in foh position, not in the front (as long as it is my decision)

Marflinger wrote: ↑Sun Feb 15, 2026 10:58 am Intending to cross at around 100 hz, which would equal to a distance of around 18 meters. (56 feet) But yes, well aware of that aspect; bill told me in the beginning.
No frontfill intended, toed in will be the way to go. Stage is in foh position, not in the front (as long as it is my decision)

The distance needed between stacks is based on the lowest frequency, usually just the high pass setting (not the top/sub crossover frequency).

The general rule is, at least 2 wavelengths between the stacks.

To calculate this, it's simply the speed of sound per second, divided by frequency, times two

The speed of sound is variable depending on atmospheric conditions, but it's typically close enough to just use standard figures. I always use 1123 or 1125 feet per second because my mind remembers it easily. Either is sufficient for the calculation. It's essentially 343 meters per second, which is also an easy number to remember if you prefer dealing in meters.

Duh my bad yes, just between two other things i racalled the wrong half of my memories.

But anyway, yes they will be distanced and yes toed in.