[SteveCallas]

Having abandoned the lightweight enclosure materials idea, it's on to a more standard construction method of MDF and plywood. 36" wide, 32" deep, 70" tall. Driver will be front firing and port will be upfiring. The enclosure will be made as two pieces - a bottom section where the driver is mounted that is MDF and ultra heavy duty (36" wide, 32" deep, 46" tall) with a multi layer baffle, and an upper section that is slightly less heavy duty (36" wide, 32" deep, 24" tall). The baffle will be 3 layers of 0.75" material and then a few more layers just behind the driver using the OSB that SI included for shipping purposes.

The bracing will all be 3/4" thick material with 9 window braces and numerous rib braces of different sizes. The port is 12" ID and I have acquired a 1.5" roundover bit to make a quasi flare on both ends. The design requires 6 sheets of material to make. This will be a big boy, roughly effective 37 net cubes with ~13hz tune. I'll feed it with a bridged Carvin DCM2000 for 2000 watts - should do 120db in room down to 10hz no problem.

I lost my access to Solidworks, so I had to make cutsheets in a roundabout way, and I tried drawing the design on engineering paper, but the numerous braces made it kind of a mess. You'll just have to imagine it from the cut sheets lol.

 

[RemixMark]

I don’t see any cuts that are ~70”. Am I missing something?

you making just one cabinet? Any reason not to make a sealed cabinet?

 

[SteveCallas]

I don’t see any cuts that are ~70”. Am I missing something?

you making just one cabinet? Any reason not to make a sealed cabinet?

Two part enclosure, a top and a bottom. 46” tall bottom and 24” tall top.

Just one HS 24 LLT would be all that is needed for my size room, but it will be in addition to six 18” LLTs.

 

[RemixMark]

Two part enclosure, a top and a bottom. 46” tall bottom and 24” tall top.

Just one HS 24 LLT would be all that is needed for my size room, but it will be in addition to six 18” LLTs.

Sorry I missed that detail. Looking forward to seeing how you assemble this enclosure. I didn't realize your other subs are ported in your room.

When does cutting begin? Are you going to finish it with something or will it be hidden in your theater and just keep it bare MDF?

 

[jmilleril]

Having abandoned the lightweight enclosure materials idea, it's on to a more standard construction method of MDF and plywood. 36" wide, 32" deep, 70" tall. Driver will be front firing and port will be upfiring. The enclosure will be made as two pieces - a bottom section where the driver is mounted that is MDF and ultra heavy duty (36" wide, 32" deep, 46" tall) with a multi layer baffle, and an upper section that is slightly less heavy duty (36" wide, 32" deep, 24" tall). The baffle will be 3 layers of 0.75" material and then a few more layers just behind the driver using the OSB that SI included for shipping purposes.

The bracing will all be 3/4" thick material with 9 window braces and numerous rib braces of different sizes. The port is 12" ID and I have acquired a 1.5" roundover bit to make a quasi flare on both ends. The design requires 6 sheets of material to make. This will be a big boy, roughly effective 32 net cubes with ~13hz tune. I'll feed it with a bridged Carvin DCM2000 for 2000 watts - should do 120db in room down to 10hz no problem.

I lost my access to Solidworks, so I had to make cutsheets in a roundabout way, and I tried drawing the design on engineering paper, but the numerous braces made it kind of a mess. You'll just have to imagine it from the cut sheets lol.

Have you considered a sonotube?

Sorry, couldn't help myself!

 

[SteveCallas]

Sorry I missed that detail. Looking forward to seeing how you assemble this enclosure. I didn't realize your other subs are ported in your room.

When does cutting begin? Are you going to finish it with something or will it be hidden in your theater and just keep it bare MDF?

The easy part of this project is that appearance doesn’t matter, it will be behind the screen. So i’ll just staple black felt or velvet to the front face of the enclosure when done.

 

[tarponater]

This thing is probably going to weigh around 500 pounds! I'm guessing there's no plans in the foreseeable future to move. Definitely following this build.

 

[SteveCallas]

This thing is probably going to weigh around 500 pounds! I'm guessing there's no plans in the foreseeable future to move. Definitely following this build.

The two parts can be separated in the future if need be, or at least that’s my hope. With driver removed, I’m hoping no one part weighs more than 150lbs.

 

[(The Other) Colin Miller]

The two parts can be separated in the future if need be, or at least that’s my hope. With driver removed, I’m hoping no one part weighs more than 150lbs.

nothing you cannot handle with a good winch. Don't worry about it, you'll be fine.

 

[Remy.Alexander]

Thats your cut sheet? What's with you few guys making us plebs look bad. Stop being so professional and awesome.

Anyway NOICE!!!! Wondering when someone would slap one these in a LLT- depending on your room that sucker should get you well under 10HZ with ease. Have fun dont break your back


So what Marty is this--

 

[SteveCallas]

For the first time in my life, I actually considered going sealed due to size and weight - and potential for delving into much lower single digits. But getting into the nitty gritty, for me, it still just doesn't make sense NOT to go LLT. Even when I apply EQ boost to the sealed that exceeds the capabilities of 2000 watts, I have a 9db deficit to the ported down low. The sealed will also be pumping out a lot of (relatively speaking) distortion below 20hz, whereas the ported will be very low distortion.

 

[Teeeejay]

You do get more with ported, but your box will be less than 1/3 the size sealed. Makes room for more subs.

 

[MKtheater]

You already had enough output, I would have went sealed to save space and weight which was a goal. Boosting the low end comes close enough in output to ported in reality and has even more weight and feel being full band. If you have no room gain I can see LLTs.

 

[SteveCallas]

You already had enough output, I would have went sealed to save space and weight which was a goal. Boosting the low end comes close enough in output to ported in reality and has even more weight and feel being full band. If you have no room gain I can see LLTs.

Just leaves too much on the table. You can see from the graph there isn’t much of anything gained until perhaps below 7hz, at which point who knows what your electronics are doing.

 

[Teeeejay]

Just get amps that don't roll off.

You should plug the ports on your existing subs and do compression sweeps and see how loud you can get before distortion/compression. I think with your size room and existing sub count you'd be pretty surprised how loud it gets.

 

[Remy.Alexander]

@SteveCallas you dont "need" to boost down low. This is some kool-aid bs being fed to people.
12x7x30 room and I still manage great results in the single digits with proper implementation. Not trying to change your mind- just properly inform you---

That 10hz-7hz is all natural. I can turn it up and get 115+DB at 7 hz I can show you my eq- I will never boost down low- also this is with 2 of my 4 subs which have no where near that ability as those 24s- being in a location with a MASSSSSSSIVE suck out at like 30hz then goes back up around 10hz.

There is a lot of BS on here and other locations about sealed that are just flat out wrong.. Heck I had argument with GSG nutjob becasue he was under the impression ported would be flatter and all ported are magically 2x louder lol (theres another kool-aid worm hole) etc he had no logical argument after I started showing him "pretty" sweeps.

Do what @Teeeejay said plug em with anything you got- sweaters towels what ever sweep and check. Youd be surprised with proper placement what you can get. Also quick reminder- your REW is at what ever watts you set it at so its assuming at as RMS- so take a few steps back breath lol I have HT18V3 on unrestricted FP20000- for reference.

 

[Jsin_N]

Nice gain at 20hz. If anything, you'll be the first to do this with that driver.

 

[SteveCallas]

If we want to get into a deeper debate of ported vs sealed, we can create a separate thread and i will happily make the case why ported always wins, but my intent was only to show the massive gain in CLEAN output below 25hz with ported. A flattish FR with 80hz highpass in play from sealed means a rising in room response with ported, which is what is needed to get the proportional effect. So the sealed to room gain 12db/octave thing doesn’t mean much to me.

 

[Teeeejay]

ported always wins

Always......

As long as you have enough space for the massive boxes, and if you don't, you don't mind chuffing or port resonance. Or as long as you don't care about output well below port tuning.

There is no ported box that would fit where I have two of my sealed boxes that would have any semblance of good response below 15Hz. So for me it was a no brainer.

In the future I'll probably build 30cuft 10Hz LLTs. But I can't fit them now. So in my setup, sealed is better.

 

[MKtheater]

It all depends. If money is an issue then ported wins around tune. 1 driver vs 1 driver. Depending on the size of the enclosure one can fit two more drivers or maybe even 3. Sealed wins in that fight, I have done all the comparison. Boost down low is needed depending on room gain profiles. I have a rising response with no boost for sealed and a peak for ported LLTs. I would build based on the room. Both can be great and there is no one solution.