Maelstrom 21 Ottoman Build - AVS Forum
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post #1 of 68 Old 06-08-2011, 01:17 PM - Thread Starter
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Hi all!

This is/was my first build and probably more ambitious than it should have been.I definitely leaped in with both feet. It was fun, exciting and trying.

Maelstrom 21"
Russian Birch 3/4" and 1/2".
Volume is 10 cubic feet.
Size is 48" x 28" x 18.5"







an MFW-15 next to the Maelstrom.




Inside with wall lined with sound dampening material and polyfil. I wanted to test it before I covered it.







So at this point I tested the sub and unfortunately I ended up with a bad driver.

But I continued on with the project.




Staining russian birch is dumb. I wont do it again, at least not with a dark stain. Takes forever and the wood doesn't want the stain.


Final coat made it nice and dark.

Off she goes to the upholsterer.

and then she came back.











I don't have a working driver, so no numbers to post. I will be powering with a EP4000. This was my first time using a table saw or router, so it was definitely a learning processes. It definitely has WAF acceptance even though I only have a GF, but she play the wife role well.

I like the height and it is a beast, but it's comfortable to put my feet up on and when I did the original testing, it didn't vibrate much at all. I used a dark chocolate color that's a leather/faux leather mix. Interesting material, but feels nice and I think looks pretty good.
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post #2 of 68 Old 06-08-2011, 06:29 PM
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Thats a really amazing build. Fantastic work, too bad about the driver, hopefully something comes up.

Does the upholstery come off easily ?
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post #3 of 68 Old 06-08-2011, 06:38 PM
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What a great idea, well implemented! Too bad about the drive-unit. How are you hiding the wiring from amp to sub? Cutting a hole in the area rug?

Seems a pity to let it sit unused, though. Have you thought about using one of the 21" B&C drivers? Less volume displacement and more EQ required, but should still work quite well. Assuming they're OK downfiring, at least.

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post #4 of 68 Old 06-08-2011, 06:56 PM - Thread Starter
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Quote:
Originally Posted by Tack View Post

Thats a really amazing build. Fantastic work, too bad about the driver, hopefully something comes up.

Does the upholstery come off easily ?

Thanks I really appreciate it.
No... All those little nail heads are holding it down, but the driver is on the bottom and is down firing. I wanted to tuft it originally, but that would have been too much of a hassle and would have required either adding 1/4 ply that would have to be glued on top of the 3/4 inch or poking holes in the 3/4", which wasn't going to happen.

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Originally Posted by DS-21 View Post

What a great idea, well implemented! Too bad about the drive-unit. How are you hiding the wiring from amp to sub? Cutting a hole in the area rug?

Seems a pity to let it sit unused, though. Have you thought about using one of the 21" B&C drivers? Less volume displacement and more EQ required, but should still work quite well. Assuming they're OK downfiring, at least.

Thank you.

I'm working on the driver issue, so I'm not currently looking at alternatives. I also don't want to create a thread about it since there's one already. Hopefully patience is a virtue.

That area rug is authentic, so I'm not going to poke a hole in it. Fortunately the amp is less than 10 feet away and I'll have a black runner on the rug. It'll be a bit of an eyesore, but I'm going to put a couch in the room and that will help hide it. The room uses Lutron lighting and the lights are rarely all the way on.

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post #5 of 68 Old 06-08-2011, 07:13 PM
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that 21 inch woofer makes the 15 look like a toy!

amazing build man, really is. cannot wait to see some graphs! if it sounds at all a good a it looks, then I am truly envious...

My first DIY project. A dual, dual opposed setup

www.avsforum.com/avs-vb/showthread.php?t=1345494
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post #6 of 68 Old 06-08-2011, 07:17 PM
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Wow - amazing for a first time build! My hat is off to you!

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post #7 of 68 Old 06-08-2011, 07:18 PM
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As an ottoman do you have any localization issues?
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post #8 of 68 Old 06-08-2011, 07:18 PM - Thread Starter
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Quote:
Originally Posted by Audiophile34 View Post

that 21 inch woofer makes the 15 look like a toy!

amazing build man, really is. cannot wait to see some graphs! if it sounds at all a good a it looks, then I am truly envious...

Thank you. I'm looking forward to graphs as well. I have built 2 dual opposed with 15's that'll be in the front of the room and I will use a miniDSP to blend them together. I'll post pics of that project soon. Just need to finish the grills this weekend.

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post #9 of 68 Old 06-08-2011, 07:26 PM - Thread Starter
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Quote:
Originally Posted by Archaea View Post

Wow - amazing for a first time build! My hat is off to you!

Thanks... It took a really long time, really long. I started last year. Waited for my bosch router, the new one, but they had manufacturing parts issues and I finally got tired of waiting and ordered a the older model.
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As an ottoman do you have any localization issues?

Yes, I have some localization issues, but my girlfriend didn't notice it. I have my 2 dual opposed that I just finished and will be in the front and that may compensate, but we'll see. The cutoff is at 80 and the frequencies above 50 seem to allow me to locate the sub. However, I had that same issue with my MX-350. The mal 21 in 10 cubic foot box with the 2 dual opposed model well and the SPL is very good with one dual opposed, so I may be able to do something to eliminate localization.

Also, I almost always think I can locate a sub, so it could just be in my head.

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post #10 of 68 Old 06-08-2011, 08:35 PM
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Whats wrong with her! I haven't heard of a 21" having the same issue as the 18's ring coming loose though I did notice they were both discontinued.

That freakin BLOWS! So sorry man. Nice build.
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post #11 of 68 Old 06-08-2011, 08:43 PM - Thread Starter
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Quote:
Originally Posted by kryptonitewhite View Post

Whats wrong with her! I haven't heard of a 21" having the same issue as the 18's ring coming loose though I did notice they were both discontinued.

That freakin BLOWS! So sorry man. Nice build.

She's a woman, to start.

Actually when I was first testing it, she got scared and ran out of the room. I wasn't even close to its full potential, but things were rattling. I can't wait to get all 3 subs up and running. They need an devil emoticon.

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post #12 of 68 Old 06-08-2011, 08:49 PM
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post #13 of 68 Old 06-08-2011, 08:50 PM
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Your going to keep running her with the 2 little boys? Why not just run the 2? Your 21" suffers from the known issue of the ring coming loose, right?
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post #14 of 68 Old 06-08-2011, 09:00 PM - Thread Starter
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Quote:
Originally Posted by notnyt View Post

very nice, what's wrong with the driver?

You can read about it here, but it's the same issue you had I believe.
I honestly don't want to rehash the issue in this thread.
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Your going to keep running her with the 2 little boys? Why not just run the 2? Your 21" suffers from the known issue of the ring coming loose, right?

Like Christopher Walken said in James Bond, View to a Kill, more.. more power. I guess you could say, I built it, so I want to use it for what I intended. There may be other options if thing don't workout.

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post #15 of 68 Old 06-10-2011, 05:01 PM
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You could probably make a sub-baffle and manifold to hold a pair of opposed 12" units that you could screw into the existing opening. Plenum could b straight or angled (as second attachment) as needed to fit them in.
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post #16 of 68 Old 06-10-2011, 10:32 PM
 
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I wonder how quad MFWs would work in this application. I believe 10 cu ft is perfect.

I guess it would take restructuring the bracing, not just a new "baffle".

A dual opposed glass-top coffee table with two drivers on top, two on bottom and a gap before the glass would be pretty hot for the visual, and inertness.

I guess we'd be talking about a cheap, large, rectangle version of Bosso's subs at that point though
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post #17 of 68 Old 06-11-2011, 12:15 AM
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Nice, thats one way to gain waf indeed.
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post #18 of 68 Old 06-11-2011, 09:28 AM - Thread Starter
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Quote:
Originally Posted by subpro View Post

Nice, thats one way to gain waf indeed.

No one can tell that it has dual purposes, they just think it's an ottoman, a big one.

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post #19 of 68 Old 06-12-2011, 07:46 AM
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Quote:
Originally Posted by pgwalsh View Post

No one can tell that it has dual purposes, they just think it's an ottoman, a big one.

Curious about wiring. Are cables going to be visible?

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post #20 of 68 Old 06-12-2011, 09:00 AM - Thread Starter
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Curious about wiring. Are cables going to be visible?

I suppose they will be if you really look for them. It's a short run and I will use a cable runner.

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post #21 of 68 Old 06-12-2011, 11:02 AM
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Great looking sub.

When will you find out about the replacement driver?

"Half the world is looking for Jesus, and the other half is looking for more bass..."
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post #22 of 68 Old 06-12-2011, 01:43 PM - Thread Starter
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Great looking sub.

When will you find out about the replacement driver?

Thanks

Hopefully this week, but I'm not sure. Kevin is testing the drivers to see what is breaking down and what is not. Each one is tested for 72 hours. I'm keeping my fingers crossed that he finds a good one. If not, I'll obviously start looking for alternatives.

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post #23 of 68 Old 06-12-2011, 02:03 PM
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Quote:
Originally Posted by pgwalsh View Post

You can read about it here, but it's the same issue you had I believe.
I honestly don't want to rehash the issue in this thread.
Like Christopher Walken said in James Bond, View to a Kill, more.. more power. I guess you could say, I built it, so I want to use it for what I intended. There may be other options if thing don't workout.

Kevin said the 21's didn't suffer from the same failure as the 18's. My 2 are working good so far but I only have about 10 hours on them both. i've been busy with my car the last month.

Blasting brown notes for 10 years and counting!

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post #24 of 68 Old 06-12-2011, 04:42 PM - Thread Starter
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Kevin said the 21's didn't suffer from the same failure as the 18's. My 2 are working good so far but I only have about 10 hours on them both. i've been busy with my car the last month.

Well I think it happens fairly quickly. It happened within 45 minutes of listening time an dI never got close to pushing the driver. When I talked to him on the phone he told me it happened to a lot of the 18's and some of the 21's. If it happens, it happens in a short amount of time. I'm hoping he can find a working one in his batch and I feel badly for the trouble he's going through.

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post #25 of 68 Old 06-12-2011, 05:25 PM
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you have done an absolutely fantastic job!

the unit looks at home in your room and i noticed that it even matches some of your other furniture. the internal construction seems good and it was a good driver choice.

the details, such as the recessed feet really give it a finished look.

kevin will get you sorted out on drivers. it sounds like he really got hosed, but has been doing his best make folks whole.

just out of curiousity, what does something like that leather upholstering cost?

there aren't many ottoman subwoofer builds around here, even though it is a really good waf solution. hopefully, yours inspires others to give it a shot or jump in with 'both feet' as you put it. :-)

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post #26 of 68 Old 06-14-2011, 07:50 PM - Thread Starter
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Quote:
Originally Posted by LTD02 View Post

you have done an absolutely fantastic job!

Thank you very much.

Quote:


the unit looks at home in your room and i noticed that it even matches some of your other furniture. the internal construction seems good and it was a good driver choice.

Yes... The nail heads match the chairs and it blends into the room well. It's dark chocolate, but has a hint of red, which is also found in the wood in the room.
Quote:


the details, such as the recessed feet really give it a finished look.

The recessed feet took a long time to find. I actually found really inexpensive triangular shaped feet for about $3.00 each. They were taller than I wanted, so I shaved them down to the proper size. They were also pre stained, but match the leather.

Quote:


kevin will get you sorted out on drivers. it sounds like he really got hosed, but has been doing his best make folks whole.

just out of curiousity, what does something like that leather upholstering cost?

The faux leather cost around $180 to $200. I was quoted real leather around $600+ and one place quoted me $900. Needless to say that place will never win me over. Total cost was around $500, but I could have had it done for less. I just happened to prefer the person I chose work over others
Quote:


there aren't many ottoman subwoofer builds around here, even though it is a really good waf solution. hopefully, yours inspires others to give it a shot or jump in with 'both feet' as you put it. :-)

You know I did it because I needed an ottoman and a subwoofer. However, I've also built two dual opposed, which you can see in the background of one my finished pics. I am just finishing the grills and will put up. They're a copy of Wembley2000's design, but slightly smaller.

Well

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post #27 of 68 Old 06-14-2011, 10:24 PM
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Have you thought off replacing this with the new mach audio IXL 21" driver when it comes out.

Not sure if the driver cutout is the same but it should be very similar.
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post #28 of 68 Old 06-15-2011, 07:20 AM - Thread Starter
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Have you thought off replacing this with the new mach audio IXL 21" driver when it comes out.

Not sure if the driver cutout is the same but it should be very similar.

I have spoken to them, but they didn't have much to offer including paramaters. The driver is deeper and I have no idea when it will be available. Obviously I'd prefer the Maelstrom because I know what it's capable of doing and the box was designed for it.

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post #29 of 68 Old 06-15-2011, 12:24 PM
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Your chairs are Thomasville? I think I have the matching sofa. Very nicely done. I wanted to do something similar for a very long time.

I'd suggest using your other subs to fill in holes from room modes, ala Geddes distributed subs. Very likely placing one in a corner.

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post #30 of 68 Old 06-15-2011, 01:31 PM - Thread Starter
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Your chairs are Thomasville? I think I have the matching sofa. Very nicely done. I wanted to do something similar for a very long time.

Thanks for the compliment.

They are Hancock and Moore, Sullivan Glider chairs with San Marcos Olive cover and ultra down filling. We have 4 and I'd like to get a couch, but I'm thinking fabric for the couch. I want something in deep burgundy with perhaps gold trip. It is the library, bar and theater room.
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I'd suggest using your other subs to fill in holes from room modes, ala Geddes distributed subs. Very likely placing one in a corner.

I have one corner loaded in the front and the other one on the opposite wall. I have to get all three running, the two little one's are finished, in order to see what I like best. Currently the two in front are quite nice.

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