[Mike Cason]

Here is my build thread for the Maelstrom 21. I'll try to provide enough quality pics during my build for you.

I'm using Kevin's Maelstrom 21"er with the passive radiator design. I normally don't like building a passive radiator sub with a Qts over .4, but it is so close, I won't have a problem.

Here's the deal....23" x 23" x 60"; 13 cubes and 15.5 hz box tuning. With the typical passive radiator design there is more of a roll off but at this already low box tuning, I'll have more than plenty of bass. I needed the height to match my main speaker's height and get the cabinet volume I need. Better WAF here.

I just picked up the pallet of materials from my mill. My construction material is 1.25" mdf. It looked like I had ten bags of concrete in my truck going down the road. In the roll of plastic, I've got two sheets of Pionite black slate laminate to match all of my other speakers.

Cabinet resonance with this thick material; I don't think so. Moving it? Now that's another challenge.

Just got back from Houston with the materials so here is the first build pic:

Read more: So where are the Maelstrom-X 21" Build Threads! - Home Theater Systems - Electronics and Forum - HomeTheaterShack http://www.hometheatershack.com/for...elstrom-x-21-build-threads.html#ixzz0XWvNWnLo

 

[Mike Cason]

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

Mike, it's nice to be the first with a successful build. I usually don't copy others because I don't feel that it was my build and that takes away a little from the fun of it all.

As far as being heavy, it's going to be like building a tilt wall concrete building and then moving it! With a subwoofer driver like the Maelstrom 21 and all of the passives working together, I want a solid cabinet which will be resonant free. It is going to be tough to work with during the build. My two stacked subs in my avatar weight 235 lbs. ea.

 

[Mike Cason]

Thanks for the very nice graph and modeling work Kevin! I've only got the QSC 1450 amps I've been using for my current subs, so it looks like I'll be upgrading the amp as well. I don't like the term clipping, and with the 1500 watt rating of the Maelstrom, my 1450s briged will only put out 1400 watts; 4 ohms at 1khz. Bring the sub output level down to the high teens or low twenties, and the amp's output will probably be down around 900 to 1000 watts maxed out and will probably clip.

John's 18" flat mdf passives I think have an fs of 3.9 at 2100 grams. 3" P-P on cone travel.

I appreciate your excellent communications, the phone call, and your service beyond what is expected out of a dealer.

VBR
Mike

This is about what you can expect with that enclosure Mike. I stuck a 13Hz subsonic filter on this, figured 20% fill and used 2000W with this simulation. I used my PR-15"s because I was too lazy to load the exact parameters for John's PRs but they should be roughly the same.

Even with 2000W (EP-2500 type amp) you have plenty of safety margin. The PRs are < 40mm P-P so they should be alright using six of them. I wouldn't worry about the main driver excursion @ 10Hz, simply because there isn't much down there and the rest of your system probably has DC blocking filters cascaded, which attenuate down there anyway. Depending on your room, I'd say you have very respectable output @ 15Hz and above. :T



Kevin Haskins
Exodus Audio

 

[Mike Cason]

Re: Maelstrom 21" Beginning build pics....

My wife got home and thought I was building a coffin to save money. I had to remind her that mdf wouldn't last very long buried.....

Well, here are the first pics.....many more to come. :blink:

I'm really not sure how I am going to be able to work with this heavy of a cabinet during construction, but that's never stopped me before. This material is so thick I used 2.5" decking screws and filled up the holes. They will be sanded and I will laminate the entire cabinet. This is just too heavy for a glue up construction project and there will be a lot of internal pressure. I did use generous amounts of glue too. :nerd:

 

[Mike Cason]

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

Mike, you are so keen I had to go out and measure. We're spot on 23" square! I'll pick up my HD binding post and the Maelstrom-21 which are in today just waiting for my anxious hands to pick up.

Thanks guys! It is very solid and heavy, and I haven't even put in the braces. I'll turn it over today to work on them.

It looks higher than it is wide. Did you change the original 23" x 23" x 60"?

 

[Mike Cason]

Yea, that's the ticket....

It looks like after the internal bracing and driver displacement, I'll still have 13 cu. ft.

This cabinet is going be better, and the 2100 gram 18" passives are going to sweeten the numbers.

Off to the doc's office and then I'll pick up the beast. :sn:

Thanks... :innocent:

It must be the resolution on my monitor that's making it look taller.

 

[Mike Cason]

Re:The Monstor Maelstrom 21" has arrived!

I wanted to keep the cabinet as small as possible at 23" squared. It's going to be a bit of a challenge to build a nice grill for this gigantic beast. I was also trying to save on the lamanite. At 23", I only need two sheets. At 24" or more squared, I would need four sheets.

Look at the size of this thing! It really should be illegal! Yep, I'm going to need a much bigger amp for sure. The build quality is incredible with what I can see.

I got some huge terminals that will accept #4 wire or bananna plugs.

More paper work to do and then back in the shop again.

 

[Mike Cason]

Thank you for that Mike,

I always love those lower numbers.

I have a Houston buyer who may be buying my complete subs tomorrow night along with one or two of my amps, which will require me to buy new passives. I have to have a much bigger amp too. I can't hardly compress the driver by pushing down!

That leaves the door open for either John's 2100 gram 18's; or Kevin's passives. John's 18"ers have a much lower fs of 3.9 which is good. I've been building subs for years and have always used John's passives when they were available.

Here is the beast mounted temporarily and the cabinet sanded. I didn't realize the driver would be so large. That's a 23" wide cabinet!! :unbelievable: What a woofer!

A grill is going to be the biggest challenge to make and look nice.

Again, thank you for your time with the modeling! :clap:

Mike

 

[Mike Cason]

re: Maelstrom 21" With 4 - 2100 Gram 18" Passive Radiators

Kevin,

How would you hook up your Face amplifiers with the RCA LFE output on my Denon? How long have they been around and what is the RMA rate of these amps?

My cabinet is too narrow with inside 1.25" for your 21" passive radiators and grills.

Much appreciated.

Mike

I have 21" PRs, which look identical to the M-21" but they are $150 each, $300/pr. Two is all you would need.

Kevin Haskins
Exodus Audio

 

[Mike Cason]

Re: Maelstrom 21"

Thanks for the info. I might budget that in a little later. I'm strapped. I found an XLR to RCA connector and have the great Reckhorn B-1 EQ which does well for me. Are the fans any noisier than QSCs or other similar amps?

I did manage to sell both of my subwoofers to a Shackster in Peoria Illinois and they are crated and ready to ship on Monday. I just need to strap them down. I'm glad I didn't part them out. They are too good to be wasted.

Thanks Kevin,

Mike

 

[Mike Cason]

You are right. AE's passives have the fs of 3.9 which is very low. I've been using his passives for many years and know his build quality. His 18s have a 3" peak to peak.

Thanks for the graph work. Very impressive work.

 

[Mike Cason]

Re: Maelstrom 21"

I've been doing a lot of research on the Face products and they have been around for 10 years now. They aren't just a new kid on the block. You must have a great product to be in this business that long. I like the looks of the torrodial power transformer and the rest of their build. I'll let you know if I can afford one.

Thanks again Kevin...

btw....My avatar is now the Maelstrom 21" subwoofer!

 

[Mike Cason]

Re: Maelstrom 21" Texas Monster

It's been far too long since I've posted some updated pics. Between finishing up getting the shipment of my other two subs ready for the trucking company, selling one of my amps, and working with my regular work, I've not had much time to work on the beast.

I've also purchased the Face F1200TS amp, XLR cable, I had the new 18" 2100 gram passive radiators built for me, and all the goodies are in transit.

I am finally breathing some life into it. Now it doesn't look too small. I need to work on internal bracing next and add a second layer of material behind the driver, probably 3/4 birch, screwed and glued. A 2 inch thick baffel should be stout enough. :unbelievable:

 

[Mike Cason]

I decided against the second sheet of 3/4 plywood for the baffel. This mdf is 1.25" thick and that's a plenty!

These photos represent a much better design. My new special center braces couples the front and the rear of the cabinet as one unit and still leaves plenty of room for the drivers and cu. ft. I need. I added the 2 x 4 to stiffen up the sides.

Tomorrow, I'll build a 3/4 birch bottom so the mdf will have some protection from damages due to moving around and I'll make two 1 x 2 red oak runners for feet like I had on my last subs. It sure makes moving them in room much easier.

I'll put in some SonicBarrier on the bottom and top of the cabinet, install the rear panel of the cabinet, and start on the laminate. I'll add some polyfil after the driver is installed and before the passives go in.

I'm sure dreading the laminate work. I don't have any room for error on the size, only purchasing two sheets.

 

[Mike Cason]

Thanks for the support! :T

I just ran the numbers again after completing the bracing, re-figuring the cabinet volume including the PR displacement and I'm still right on 13 cu.ft. 15 to 16 hz with room gain should make this a very acceptable build. :hsd:

I used to be so impatient with my projects when I got started years ago. I have learned to take my time and put in the extra labor to make my projects perform well and look nice which pays off in a big way.

 

[Mike Cason]

WOW, you have done extremely well.

Those subs are going to have more head room than anyone would ever realistically use. And thats a great thing

I'm only building one, "but the song still remains the same"!

 

[Mike Cason]

It looks small in that picture.

Kevin Haskins
Exodus Audio

Kevin,

It looks much bigger now. That's a 22" monitor up against it and the desk is 3' deep. I can't wait to hear this XBL2 21"er.... :foottap:

 

[Mike Cason]

Looks good! Looking forward to seeing this all come together!

Raven,

I read you were finishing yours up a few days ago. What did you build and do you got a pic?

 

[Mike Cason]

Thanks for the link. You did a nice job. Did you get down to 15 hZ?

Yea you're right....I noticed a lot of "this is what you should have done" comments. PMs work well instead of that kind of posting.

Be happy and enjoy the fruits of your labor. You've got real bass now!

Mike

My Maelstrom-X 21" Build Thread

I don't have "final" pictures of it yet. Once it's in place in the livingroom/theater, you really can't see anything interesting. I'll have to pull it out into the middle of the room, take a few photos, and push it back into place.

I'll probably be "finishing" it in truck bed liner, once I figure out what the most economical option is. I'd love to have a local shop spray it, but I can't find any that will take me seriously, or give me a good quote on it. They are too narrow minded to be open to spraying something that *isn't* a truck bed.

Plus measurements...I'm not even sure where my mixing board and Behringer mic is.

Your build makes me want to build a second one of these....or maybe an 18" LLT to compare side by side...but my budget wouldn't allow it. On the plus side, my fiance doesn't care what I put in the livingroom/theater, because she knows I have my own skewed, but decent sense of aesthetics.

 

[Mike Cason]

Hanging or gluing polyfill to the top and upper sides of a tall subwoofer cabinet would not ensure that it wouldn't be down in one of your drivers shortly after cranking it up. With my design, there's not much room to attach any raw poly to much surface area.

I decided to take my audio grill cloth and make a very tight and porous "basket" and fill it with the polyfil and seal it up so none could fall out.

I also installed some Sonic Barrier I had in stock and put in on the top and bottom of the cabinet to absorb any potential resonance and standing waves. I may just add some more loose polyfil when I'm done in the bottom just before I install the bottom two passive radiators, or I may leave it as it is and run my Linkwitz frequency CD on it and see where I'm at on my tuning frequency. I may have enough fill already with the "basket fill", plus the Sonic Barrier. It's easy to remove a passive radiator and add some if I think I will need more.