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*****The 42's: Maelstrom 21" sub box (NEO Dan design).....dual box build*****

post #1 of 111
Thread Starter 
1st off.....this is my first build.

Second.....I'd like to thank NEO Dan, bossobass, Kevin Haskins, and anyone else I've pestered via PM's asking for advice.

Third.......Please don't hesitate to ask me any questions......as there is probably some things I've not thought about or just don't know. I feel like most of you have forgotten more than I know about DIY.

My story......I originally came to the AVS forums looking for some advice for replacing my Polk speakers. Then a bit later, as luck would have it, I blew one of the woofers. I set out trying to find a replacement woofer, which in a round about way lead me to searching all the DIY forums I could find. I've been trying to do as much research as possible for the last 6-7 months or so.






So, I'll be building two sub boxes with an internal volume of 11.72³ each.

2 - 21" Maelstroms

1 - Marchand BASSIS

1 - Marathon MA-5050 amp
Quote:


The M-21 is 4 ohms? If so, 2 in series at 8 ohms, the MA5050 is rated at 5KW peak output and should give 2400W bridged into 8 ohms out of a dedicated 20A outlet.



I'm using 1" Baltic Birch.








This is a design by NEO Dan.......

3D image in SketchUp:

http://sketchup.google.com/3dwarehou...27&prevstart=0



















Picking up the 1" Baltic Birch........








For reference.........








Got the large sheets broken down with the help of my TrackSaw........makes it much more manageable for me solo on the table saw. I can't begin to tell you how much 1" BB 4' x 8' weighs moving it around by yourself.....lol












Getting the braces ready........




My helper.......although all she does is sleep. lol


post #2 of 111
Thread Starter 
Internal braces are in.......








Again......breaking the large sheets down with the track saw to make them more manageable on the table saw....







More like it.......







Getting ready for rear panel......





Rear panel in.........



post #3 of 111
Thread Starter 
Working on box #2.....








Working on adding brace for rear panel........













Few things from FedEx/UPS yesterday..........All three vendors had great communication and super fast shipping.




10 gauge mil spec wire from ApexJr. arrived.


http://apexjr.com/wire.html?JRSource...rctysKw#Teflon









Acousta-Stuff Polyfill........10 lbs.

Neutrik speakON connectors......


http://www.parts-express.com//pe/psh...44&rak=260-330









My 2" and 4" OC703 came in as well........

http://www.atsacoustics.com/cat--Fib...ards--106.html



post #4 of 111
Thread Starter 
One box w/ 4" 703.....or as much as I can do until the front baffles go on.



















So my car audio bud came over today to help me cut the radius' and rabbits........

We got the three 1" layers complete for the baffle......changed up a bit from Dan's design. I'm going to add a fourth layer. I'll explain that in a bit......

















Chad standing next to box for size perspective........

post #5 of 111
Thread Starter 
Getting closer......lots of help today from my buddy. One almost complete......try to get the other one semi complete tomorrow.

Then Sun. attaching woofer, wire, solder, etc........





















A few things came in this week........


Marchand Bassis







Marathon 5050

Good lord this amp is heavy!











Lots to do today.........flush trim router work, mounting woofers, wiring, soldering etc.....

Everything should be completed today. Everything except the final finish. Gonna get them broken in and "field tested" this coming week with 4 nights of house parties starting Wed. night.
post #6 of 111
Thread Starter 
Flush trim bit router work complete..........drivers wired up and installed. Front baffle edge rounded over with 3/4" bit.








Didn't know what to put beside the boxes for size perspective.......used a 4' level:







Free Paradigm feet from my awesome dealer:


post #7 of 111
Reserved
post #8 of 111
Man,this thread will turn out awesome! Can't wait for you to start rolling the pics.....
post #9 of 111
Yeah baby! I'm curious how the Marathon will do with a pair of these. I've been thinking of getting one for my pair of maelstroms (their ONLY 18's).
post #10 of 111
Monstrous.

Hey, you're not far from me...

ROAD TRIP!!!

How big's the room? Is it open to the rest of the house or what? Details, man.

If you need a hand, LMK. I'm the best onlooker you'll ever meet, and I can turn beer into pi$$ with nearly zero effeort.

Bosso
post #11 of 111
Ah BM,
Good to see you. Man have I been in Alzheimers mode
I need to revise the baffles to clamp the woofer down correctly. That is if you've not done the router work already.
Since this driver has a foamie gasket on the front, that I'd rather not crush down to nothing. I think the best route is to use just the outer lip of the basket, I think it's about 1/8" wide. It would be nice if you had some of the thin gasket foam that PE sells (#260-542) to make a seal, it would probobly be best to apply this to the box instead of the driver.
post #12 of 111
Quote:
Originally Posted by bossobass View Post

I'm the best onlooker you'll ever meet, and I can turn beer into pi$$ with nearly zero effeort.

I'd argue the point with you but we'd just end up in a pi$$ing contest
post #13 of 111
Quote:
Originally Posted by bossobass View Post

.....

If you need a hand, LMK. I'm the best onlooker you'll ever meet, and I can turn beer into pi$$ with nearly zero effeort.

Bosso

Nice.... though that sounds like most of the help I tend to get.....

Wow - I thought the Shiva X2 was big....
post #14 of 111
Something like this:
Using the PE gasket tape
post #15 of 111
So, for the curious among us, how much is 1" thick Baltic Birch for a 4x8 sheet?

BTW, those should be some nice subs!
post #16 of 111
Thread Starter 
Quote:
Originally Posted by WiSounds View Post

Reserved

haha......go easy on the noob.....

Quote:
Originally Posted by Kanaris View Post

Man,this thread will turn out awesome! Can't wait for you to start rolling the pics.....

Will post some build pics tomorrow of what I've got so far......

Quote:
Originally Posted by robseyes View Post

Yeah baby! I'm curious how the Marathon will do with a pair of these. I've been thinking of getting one for my pair of maelstroms (their ONLY 18's).

post #17 of 111
Quote:
Originally Posted by Stereodude View Post

So, for the curious among us, how much is 1" thick Baltic Birch for a 4x8 sheet?

BTW, those should be some nice subs!

I too am interested in this, and where can you find 1" plywood in general because lowes and home depot only have up to 3/4".
post #18 of 111
Thread Starter 
Quote:
Originally Posted by bossobass View Post

Monstrous.

Hey, you're not far from me...

ROAD TRIP!!!

How big's the room? Is it open to the rest of the house or what? Details, man.

If you need a hand, LMK. I'm the best onlooker you'll ever meet, and I can turn beer into pi$$ with nearly zero effeort.

Bosso

Don't offer if you don't mean it.... I'm quite confident on my woodworking skillz and have absolutely no confidence on the "electronic" side of things.

My room is 15' x 34' with 10' ceilings. Carpet floors, sealed room......

Here is the room layout......




This is my space at the moment.......planning a dedicated theater room in the next couple of years.


Quote:
Originally Posted by NEO Dan View Post

Ah BM,
Good to see you. Man have I been in Alzheimers mode
I need to revise the baffles to clamp the woofer down correctly. That is if you've not done the router work already.
Since this driver has a foamie gasket on the front, that I'd rather not crush down to nothing. I think the best route is to use just the outer lip of the basket, I think it's about 1/8" wide. It would be nice if you had some of the thin gasket foam that PE sells (#260-542) to make a seal, it would probobly be best to apply this to the box instead of the driver.

Quote:
Originally Posted by NEO Dan View Post

Something like this:
Using the PE gasket tape

Thanks for that pic.......I haven't cut the radius yet.......maybe on Wed.


Quote:
Originally Posted by Stereodude View Post

So, for the curious among us, how much is 1" thick Baltic Birch for a 4x8 sheet?

BTW, those should be some nice subs!

I'll update you with the cost of the BB in the morning. The invoice is at my office and I've lost that one brain cell that remembered the cost. I wanna say it's in the $115/sheet + tax range.....but don't quote me on that.
post #19 of 111
Thread Starter 
Quote:
Originally Posted by Scarier View Post

I too am interested in this, and where can you find 1" plywood in general because lowes and home depot only have up to 3/4".

A company in Charlotte, NC called "Dealer Imports".........they supply cabinet shops exclusively......Even though I'm a general contractor, I still had to purchase the BB through one of my cabinet subs.
post #20 of 111
Here's the render based on that info and a 19.25" mounting diameter:
Route out some spots so you can pry the driver out should you ever have the need.
post #21 of 111
Do you need hardware?

post #22 of 111
I've updated the online model in the 3D Warehouse.
post #23 of 111
Nice project, this is one of the rare subs that can fill a good size room with little effort.

Two of these should give you headroom to spare.
post #24 of 111
Sweet!

'Bout time someone does a dual 21" Mal build.

Excellent!
post #25 of 111
No replacement for displacement, lol!

Subscribed.
post #26 of 111
This is going to be epic..
post #27 of 111
Surprised Scott isn't chiming in here.....


dbl
post #28 of 111
Thread Starter 
FYI.......the 1" Baltic Birch was $119.61/sheet after tax..........

Gotta run out......I'll answer the other ?'s in a bit.
post #29 of 111
Quote:
Originally Posted by NEO Dan View Post

Do you need hardware?


where do I get THOSE!
post #30 of 111
Thread Starter 
Quote:
Originally Posted by NEO Dan View Post

Do you need hardware?

Still trying to decide.........like Health Nut.....I tend to agonize over the details.....and when I'm in unfamiliar territory, probably moreso.

I was wanting something like this......just longer.

http://www.madisound.com/catalog/pro...oducts_id=8199

McMaster-Carr doesn't have anything like it..........and they have everything.



Quote:
Originally Posted by dbldare View Post

Surprised Scott isn't chiming in here.....


dbl

Is that good or bad? lol
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