BillFitzmaurice.info

I was reading Rich's post and it reminded me of a curiosity I had. And that was just enough impetus to get me to post about it.

Bill, I'm sure it's a size limitation... would it really be unreasonable large to design a cab that has the extension of a T60 combined with the sensitivity of a T48? How big would that sucker have to be? I'm thinking 6-7 feet long x 30 x 36 and intended to be only used V-plated could still be a manageable package in groups/stacks of 4-6. Would it have to be much larger than that?

Does "loud/low/small- pick 2" ring a bell?

Loud and low has to be big.
And, to what end? Live music doesn't need it.
Recorded music may, but since a doubling of cabs adds +6dB, or there is free output to be gained in width, why chew up so much ply on 1 cab for something that might not equal the gains of either of the other options I just mentioned?

It sometimes isn't possible to V plate...

I can always count on you, Grant, for a devils advocate point of view

Grant Bunter wrote: ↑Wed May 31, 2023 2:46 am Does "loud/low/small- pick 2" ring a bell?

Loud and low has to be big.
And, to what end? Live music doesn't need it.

I hope the above occurs as obvious to all the casual readers of this forum. Better stated than not, I suppose. To be safe.
For any who aren't aware of what Grant is referring to, Josef Anton Hofmann - Hofmann's Iron Law
You're right, Grant. Live music doesn't typically require anything more than T39 has to offer for extension.

Recorded music may, but since a doubling of cabs adds +6dB, or there is free output to be gained in width, why chew up so much ply on 1 cab for something that might not equal the gains of either of the other options I just mentioned?

It would take thirteen 20" wide single LAB12 loaded T60's, or nine 28" wide single LAB15 loaded T60's, or seven 30" wide double LAB12 loadedT60's to match the output potential of four 36" single 3015LF loaded T48's v-plated at 40Hz. I think the gains would be justified, as long as it could be done in a footprint that's still relatively portable and deployable.

I know you don't, but if you did have the desire to fully utilize the extension of the T60, (transport allowing) wouldn't you rather build nearly half (or less, depending on the configuration) the amount of cabs and buy half the amount of drivers? I'm not at all convinced there's any savings in plywood either. But, a person building something of that magnitude really shouldn't be worried about the cost of ply.

It sometimes isn't possible to V plate...

That is true.

Shall we call this thing the T-Mega? Feel free to use the name, Bill. XD

Seth wrote: ↑Wed May 31, 2023 11:06 am It would take... nine 28" wide single LAB15 loaded T60's... to match the output potential of four 36" single 3015LF loaded T48's v-plated at 40Hz.

So to answer your original question, Seth:

Valuing the V-plate as a 4.5th T-48, and from my memory (lol) that Titan's are 2x as loud as Tubas, it would basically be a T-60 of double the volume. So double the dimensions and go with max width. So 60x27x120? It would work as a permanent install, and easiest to build in place.

Would a single LAB15 be sufficient?

If you want to get the maximum out of a LAB 15 build a 22 foot long 80 cubic foot horn. If you want something practical build T60s, as many as is required.

Bill Fitzmaurice wrote: ↑Wed May 31, 2023 12:31 pm If you want to get the maximum out of a LAB 15 build a 22 foot long 80 cubic foot horn.

Seth???

Bill Fitzmaurice wrote: ↑Wed May 31, 2023 12:31 pm If you want to get the maximum out of a LAB 15 build a 22 foot long 80 cubic foot horn. If you want something practical build T60s, as many as is required.

Is there a way to design a horn path that maximizes sensitivity between 30 and 60Hz closer to that of the T48 and also maintain the extension of the T60, without drastically changing the horn length of a T60? Same-ish horn length, larger enclosure with flair rates (if that's not the correct term, forgive me) to increase sensitivity in that region? Would it be possible to do in an 84x30x36 enclosure designed to be deployed in a stack of 4 or more, V-Plated? I wouldn't mind so much, giving up substantial sensitivity over 60HZ if that helped fit everything in the package.

Tony Hoffman won't allow it. (I knew him, BTW. When people started spelling his name with two F, as did Dustin, he went with it.) If you want T48 to go lower or T60 to have higher sensitivity the answer is the same: Make it larger. Or build two.

Bill Fitzmaurice wrote: ↑Wed May 31, 2023 3:11 pm ...If you want T48 to go lower or T60 to have higher sensitivity the answer is the same: Make it larger...

I'm not sure if you remember the video user accousticscience posted a month or so ago, where they scaled your design way way down and also scaled the test frequency range up.

Is it really just a matter of scaling up the dimensions of a T48 a certain percentage based on a target corner frequency? Sounds too simple. But simple is good. I like simple.

If you simply scale up the throat area and rear chamber volume will scale up as well, reducing performance, so it's not that simple.

That makes sense. Thanks Bill

Bill Fitzmaurice wrote: ↑Wed May 31, 2023 3:11 pm Tony Hoffman won't allow it. (I knew him, BTW. When people started spelling his name with two F, as did Dustin, he went with it.)

Ever thought about writing an autobiography? The cookie crumb stories you tell here and there are fascinating!

Bill Fitzmaurice wrote: ↑Wed May 31, 2023 12:31 pm If you want to get the maximum out of a LAB 15 build a 22 foot long 80 cubic foot horn. If you want something practical build T60s, as many as is required.

If there is one thing the DIY community likes it is overkill. I'm ready to preorder!

Joe

Fastskiguy wrote: ↑Thu Jun 01, 2023 5:49 pm If there is one thing the DIY community likes it is overkill. I'm ready to preorder!

Joe

Oh yeah, the guys that do outdoor "renegade festivals" would be all over something like that. A six cab stack with 9' tall by 10' wide horn mouth would make quite the bass cave at sub 40Hz frequencies. Let alone the visual appeal of such a massive stack.

Seth wrote: ↑Thu Jun 01, 2023 6:33 pm A six cab stack with 9' tall by 10' wide horn mouth would make quite the bass cave at sub 40Hz frequencies. Let alone the visual appeal of such a massive stack.

Build something like that and there's no need to ponder wall loading- you're IN the horn!