[sub_crazy]

Wow, you do excellent work even with a cold!

I have never lined the walls with egg crate foam for a sealed enclosure, so far I have just used poly fill from wal-mart. For this massive enclosure those cheap pillows from wall-mart will probably be a better idea as it would not be as messy.

As far as bracing it looks good to me so far, Kevin would have a better idea if magnet bracing is advisable but I personally never do it even with really heavy magnet drivers. I would definitely double up on the front faceplate were the driver mounts, you might even consider 3 layers.

This is gonna be a monster, can't wait until you fire this beast up:flex:

 

[SteveCallas]

Not to detract, but really, if you went that big anyway, you may have well just gone ported 18".

Are you going to triple up the plywood for the baffle?

 

[Lonely Raven]

Wow, you do excellent work even with a cold!

I have never lined the walls with egg crate foam for a sealed enclosure, so far I have just used poly fill from wal-mart. For this massive enclosure those cheap pillows from wall-mart will probably be a better idea as it would not be as messy.

As far as bracing it looks good to me so far, Kevin would have a better idea if magnet bracing is advisable but I personally never do it even with really heavy magnet drivers. I would definitely double up on the front faceplate were the driver mounts, you might even consider 3 layers.

This is gonna be a monster, can't wait until you fire this beast up:flex:

Thanks...this is my half-arsed work. When I really get into, I do silly woodworking tricks that nobody would see, and would take 4 times as long, just so I could say I've tried it.

Not to detract, but really, if you went that big anyway, you may have well just gone ported 18".

Are you going to triple up the plywood for the baffle?

I went with what Kevin suggested...but a little larger. I figured he wouldn't steer me wrong. So are so many people knocking this build?

Maybe you could be a little more helpful and offer suggestions to help me along with what I *am* doing rather then tell me what I should have done?

I've planned for doubling the baffle...it was another question in my pre-build thread that nobody bothered to answer. Is tripling suggested or required? :dontknow:

If tripling is needed, I could probably cobble enough cut-offs to make a middle layer for the two solid layers I've already cut. The way I'm planning it, is one layer will be inside the box, and the second layer will cover the whole outside walls. A third layer would allow me to recess the driver 1/4", which I'm not sure is necessary in any way, or will make any difference considering how much travel the cone has...but it would look nice. Come to think of it, I might have a piece of MDF that might work as a middle layer. But that would add a bunch of weight.

 

[sub_junkie]

That looks good Raven :T Great work...and with a cold of all things. When I built my box, I had a pretty bad case of the flu. Everything seems heavier huh? :bigsmile: And not to mention the fact that all your energy is gone to.
Thank God my Uncle was there helping me though. :help:

I'm looking foward to hearing how you think it sounds.

 

[Lonely Raven]

That looks good Raven :T Great work...and with a cold of all things. When I built my box, I had a pretty bad case of the flu. Everything seems heavier huh? :bigsmile: And not to mention the fact that all your energy is gone to.
Thank God my Uncle was there helping me though. :help:

I'm looking foward to hearing how you think it sounds.

OH, dude, you nailed it right there. I'm feeling like my arms are made of lead, and I'm looking at these big panels like what the am I doing! So I'm working in one hour shifts, then I go sit and read for 20-30 minutes, then go back to working on the sub.

 

[sub_junkie]

I was looking at the Mal-X in my Uncle's house, and I thought the more I looked at it thinking I had to carry it out to the box, it looked like it just kept getting bigger...and bigger...and bigger. So, to remedy this, I simply stopped looking :bigsmile:
It was quite a task getting the box with the sub installed in it into his F-150 that has 6 inch lift and about 20in. or so tires on it to. haha

 

[SteveCallas]

Yeah I'd definitely go three layers with a 21" high excursion driver in a sealed enclosure, possibly four.

 

[Lonely Raven]

Yeah I'd definitely go three layers with a 21" high excursion driver in a sealed enclosure, possibly four.

Wow! That's a lot of wood...I'm going to have to return the 2" screws I got and buy some 3" ones then! Thanks for the heads up!

 

[Drizt]

This is one serious DIY job. Can't wait to see how it all turns out.

Those 21" jobbies are drool worthy

How heavy is this thing going to be?

Whenever I see these big subs I curse having an upstairs listening area. I would have such a hard time trying to get these up stairs and around corners while doing so :coocoo:

 

[Christos]

I don't see any reason to go ported either.Go sealed all the way!I am looking forward to see photos of the upcoming project...:T

 

[tcarcio]

That is one giant box. Looking forward to seeing the completed sub.:T

 

[Lonely Raven]

It took me most of the weekend to get the bracing glued up as tight as I'd like, plus I spent some time with the family on Sunday. So I still have the baffle to cut out (three or four layers, yikes!), I'll have to get some longer mounting screws if I'm tripling the baffle, and I need to pick up some pillows for air-space stuffing. The top panel is already cut but not installed till I'm sure I have all the things I need. Plus I want to silicone some of the bracing as an extra insurance the box wont rattle, and maybe add a couple sticks here and there for further bracing.

Coming down to the final stages. Probably a couple days left till it's done. So much for getting it done over my vacation weekend!

 

[Mike P.]

Got any build pics?

 

[Lonely Raven]

Got any build pics?

Mike, drink some coffee before you post! Check the first page! :wave:

I have no build pics since glueing in the bracing, because it looks just like the dry fit of the bracing. I'll have more as I actually make some progress over the next couple of days. It's going to be difficult to squeeze in any time on this now that I"m back to work... :sweat:


I'm still wondering if I need to line the walls with egg crate foam or stuff the airspace with pillows?

 

[Mike P.]

Mike, drink some coffee before you post! Check the first page!

Point taken. :whistling:

I'm still wondering if I need to line the walls with egg crate foam or stuff the airspace with pillows?

The application notes say 100% fill.

​

 

[Lonely Raven]

Point taken. :whistling:

The application notes say 100% fill.

​

Ahh, I must have missed that. Is there a calculation for 100% fill? I thought I remember reading it was X amount of stuffing per cubic foot. But I can't find that info right now. What exactly constitutes 100% fill?

 

[sub_junkie]

I have heard many reports of people saying that 1 pound per cu.ft equals a 25% increase in box size, and others saying only a 10% gain per pound.

 

[Lonely Raven]

I have heard many reports of people saying that 1 pound per cu.ft equals a 25% increase in box size, and others saying only a 10% gain per pound.

Mike P and I just chatted about this. I'm not sure how much virtual gain you get, but he agrees 100% fill is 1# per cu.ft. of airspace. Honestly, I'm pretty sure I'm over 15 cu ft right now. I've not posted the exact dimensions of the box in this thread (I'll update the first post when I'm closer to done), and I've not calculated the bracing as I'm adding more and cut out a lot of "windows" in the bracing. Plus I'm surprised to find the specs for the M-21 have it at only .2 displacement?!? With sealed, and after re-reading the PDF on the M-21, bigger won't hurt anything, but I'm pretty sure I'm past the point of diminishing returns.

Looks like I'll be pillow shopping tonight regardless.

 

[Mike P.]

I looked it up. Kevin states that "about 16oz. of poly-fill per cubic foot is 100% fill".

​

 

[Ryan Anderson]

Ahh, I must have missed that. Is there a calculation for 100% fill? I thought I remember reading it was X amount of stuffing per cubic foot. But I can't find that info right now. What exactly constitutes 100% fill?

who needs to drink his cofee now?