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

57903 Views 180 Replies 23 Participants Last post by Mike Cason, Jun 1, 2010

Mike Cason

Discussion Starter · Nov 21, 2009

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

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61 - 80 of 181 Posts

Lonely Raven

· #61 · Dec 3, 2009

I did mean 5hz, but as I said, my measurements are suspect till I figure out why they look so odd.

I'm going to tackle measurements again tonight since my movie night for this Friday was canceled. I've been in a rush to get more absorbers and diffusers built before this movie night, but now I can take my time and figure out my measurement issues. Again, 15Hz is no problem, even in my open floorplan.

Mike Cason

Discussion Starter · #62 · Dec 3, 2009

Lonely Raven said:
I did mean 5hz, but as I said, my measurements are suspect till I figure out why they look so odd.

Again, 15Hz is no problem, even in my open floorplan.

You also have room gain to add to that as well, so that will help. 16hz is the lowest note from an organ.

I just got in with the passives and $75 more in hardware to finish the subwoofer and add more mass to the passives. I have to add 500 grams to each of them to get my 2100 grams. My supplier only had the 18" 1600s partially built, so I told him to just finish them and I'll add the extra mass to the suspension to get my 2100s.

Can't play in the forums and work on the sub at the same time so it's time to get back at it.

Mike Cason

Discussion Starter · #63 · Dec 3, 2009

3

Ok, I can play in the forum a minute or so.... :wave:

I've got the bottom painted, the routed and sanded Red Oak runner feet installed, and to tease and taunt ya a bit, I temporarily dry fitted the sub and couple of passives. It looks so small in these pics!

I've still got to fill in the wood around the bottom of the cabinet and sand it down square to get it ready for the laminate. We may get snow tomorrow and the coldest temps of the season, so that's not a good time to fire up my blast furnace and spread contact cement. I may get postponed on the laminate tomorrow. I'll get the final mass loaded in the passive radiators tonight and have them sit overnight in the house with the Devcon two part epoxy. That will be just another step out of the way.

Well Lonley Ravin, here are more teaser pics for ya. Just wait till the black slate Pionite is on! They will really look sharp then. Look at that massive terminal. They will accept bananna plugs, ring terminals, or up to a #4 supply wire! :heehee:

Without the drivers in place, I was able to stand it up in the upright position. I don't have a clue how I'm going to weigh it. I might get two scales, balance it on a 2 x 6, and sum the totals of the scales. But in reality, who cares! :flex:

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Pikefish

· #64 · Dec 4, 2009

Wow, there's the star!! Makes me wonder what I'm doing buying Tempests.
Oh yeah, runout!:bigsmile:

Good plan with the scales, or if you've only got one set you could put it under one end at a time, and prop the other end with something like the scales for a really close approximation.

Lonely Raven

· #65 · Dec 4, 2009

Looking good, Mike!

I've finally gotten my act together and updated my thread with photos and measurements, and even a cheesy video for the excursion fanatics.

I'm betting that your box, even though smaller, and even without the weighted passives, is heavier then my completed box! Though I don't *see* any resonation in my larger side panels, I can physically see the box rock a few mm forward and back when the Maelstrom is going full tilt. It's a trade off for a box I could actually move on my own. I swear this box is lighter then my dual folded horn which was MDF with a pair of JL Audio 10"

I don't envy you're having to move those beasts, but I'm betting once in place they will be stunningly good!

Mike Cason

Discussion Starter · #66 · Dec 4, 2009

Lonely Raven said:
Looking good, Mike!

I've finally gotten my act together and updated my thread with photos and measurements, and even a cheesy video for the excursion fanatics.

I'm betting that your box, even though smaller, and even without the weighted passives, is heavier then my completed box! Though I don't *see* any resonation in my larger side panels, I can physically see the box rock a few mm forward and back when the Maelstrom is going full tilt. It's a trade off for a box I could actually move on my own. I swear this box is lighter then my dual folded horn which was MDF with a pair of JL Audio 10"

I don't envy you're having to move those beasts, but I'm betting once in place they will be stunningly good!

You did good with the video. How much power were you giving the driver? You did a good job with the thread and your build pics too. I'm glad you are done and am enjoying it.

BTW.....hate to burst your bubble, but the first one with a finished 21" Maelstrom subwoofer takes the first slot in product completion. That includes the finishing work and grills if used. You better get to that bedliner shop quick!! My laminate goes on today! :devil:

You are right on the weight. I think my sub probably has double the weight of yours. It took everything I had to pick up one end of the cabinet to stand it upright, without the drivers. I wanted to make sure I had no resonance and as usual, I overkill everything I do.

Lonely Raven

· #67 · Dec 4, 2009

I threw a table cloth over mine that blends in perfectly with the decor. It's now "finished" :heehee:

I was running an EP2500, bridged mono on mine, but the input from the HTPC was a little lower then usual, and I only have the volume on the the EP2500 at 1 o'clock. So I have some breathing room. The EP2500 doesn't test out as very efficient at 20Hz and below as well. I just can't afford a more robust amp at this time. This should do fine for now.

I totally understand the overbuilding...I usually overbuild so I'm not left wanting...but I also promised myself I wouldn't build a back-breaking box again since I might be moving it a bit, plus, I got the 3/4 plywood on sale...which helped me get the project done within budget (which was blown with the 21" driver over the 18" driver), and almost in the time frame I projected. If I had access to the materials you have, I would have considered overbuilt, if I didn't promise myself to keep the weight down.

Mike Cason

Discussion Starter · #68 · Dec 4, 2009

Raven,

I wouldn't even have considered using the 1.25 mdf unless it was a sub....I'm regretting it now, but by the end of the weekend, I'll be happy with it, I hope. It is snowing and I'm higher than the sky it's falling out of. I really enjoy this laminate work now!!! :whistling: Anybody got some more contact cement? It's a trip......I've also learned how to route thumbs now. It aint fun or pretty......two sides are done now and only two left to go and then the top. I'm staying with it till it's done tonight if I've still got all of my fingers left.....

Sorry, you can't hide behind the ladie's skirt.....the sub has to be finished........:clap:

Payback time here buddy.....

Lonely Raven

· #69 · Dec 5, 2009

Hahaha! Good one, Mike.

Careful with the sharp objects there!

I think this weekend is going to be family stuff and working on sound treatment. Enjoy your subs!

Mike Cason

Discussion Starter · #70 · Dec 5, 2009

Lonely Raven said:
Hahaha! Good one, Mike.

Careful with the sharp objects there!

I think this weekend is going to be family stuff and working on sound treatment. Enjoy your subs!

I'm kind of new to this stuff, but does "working on sound treatment" mean telling everyone to shut up while you're working?

addle:

Hey dude.....it's Woodstock all over again here.....you can't imagine all of the colors and things I'm seeing again. I don't want to open the door and lose it all.....I'm just about done with the laminate and the drivers go in tomorrow! Weeeee...... I've just got to figure out how to wire these passive radiators!

Kevin Haskins

· #71 · Dec 5, 2009

Mike Cason said:
I'm kind of new to this stuff, but does "working on sound treatment" mean telling everyone to shut up while you're working? addle:

Hey dude.....it's Woodstock all over again here.....you can't imagine all of the colors and things I'm seeing again.

Ok Mike.... no making love in public.

Kevin Haskins
Exodus Audio

Mike Cason

Discussion Starter · #72 · Dec 5, 2009

3

Well, it's 9:40 p.m. 8 hours of labor, and one gallon of contact cement later. I had to get the laminate on tonight because it's going to be in the 20s in the a.m.

HERE YA GO RAVEN! More not so whimpy build pics! All of the laminate is done and there is about 3 hours of seams to be beveled, cleaned, and treated before the drivers can go in tomorrow. Fast enough fer ya now?

Kevin, I normally don't do this, but I've been making love all day and I'm going to share my lady's pictures with you. Actually you will see her from 3 angles.

Everyone have a great evening cause this ole Texas boy is tired and ready to go in for the nite.

Drumroll.......here she is:

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robbo266317

· #73 · Dec 5, 2009

That is awesome, I don't think I would like to be close when it gets angry.....

Mike Cason

Discussion Starter · #74 · Dec 5, 2009

robbo266317 said:
That is awesome, I don't think I would like to be close when it gets angry.....

Thanks, I've designed her so that she can be very sweet and generous, or as brutal as you want her to be! :heehee:

Mike P.

· #75 · Dec 5, 2009

Looking good Mike! :T

Mike Cason

Discussion Starter · #76 · Dec 5, 2009

Good morning Mike...and thank you.

I hope to start the beveling and clean up of all of the corners about mid morning. I would love to go ahead and install the drivers and get to jammin, but I'm doing things right, careful, and want a very nice looking project when I'm done. I appreciate your suggestion about the Maelstrom 21. I didn't even know they were out!

I got a phone call from a very excited person last evening. He was the buyer of my other subs. He said they arrived in Peoria Illinois yesterday afternoon and the truck driver said it was the best and most careful packing job he ever saw. The subs arrived on a pallet in mint condition. I explained the various wiring options he had with the dual terminal cups on each dual driver sub, which he loved. I suggested to him that he reads the Houston DIY forum to see the reviews from the members after we had our auditions. He is buying one of Crown's top of the line amps to drive them.

It's cold here so I'm not so slap happy to get back to work on them, but for $25.00, I can buy some kerosene and fire up my forced furnace and keep at it. Knowing where you live, you are probably sitting there laughing at me complaing about my mid 20 degree weather when it gets 40 degress or more below the -0- degree mark there.....

We'll see how much more gets done today. I would love to have the drivers installed and the grill work started by day's end. Have a fantastic weekend....:sn:

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Lonely Raven

· #77 · Dec 5, 2009

That looks fantastic, Mike! It looks like you really will be the first one "finished". And in record time too!

Edit: Peoria is only a few hours south of me. Maybe I'll run into your old Maels someday.

Mike Cason

Discussion Starter · #78 · Dec 5, 2009

Lonely Raven said:
That looks fantastic, Mike! It looks like you really will be the first one "finished". And in record time too!

Edit: Peoria is only a few hours south of me. Maybe I'll run into your old Maels someday.

Thank you Raven.....my other subs were the dual 2 ohm 15" Soundsplinter RLP-15s; 2 subs with two drivers and 4 - 15" passives each. The Maelstroms weren't out when I built them.

With all of the discounts and special deals I got, I'll have close to the same amount of money in this sub that I sold my other two subs and two amps for. Maybe $200 more, max. That includes the new F1200TS amplifier. Just a of a lot of labor.

Lonely Raven

· #79 · Dec 5, 2009

Wow! That's quite a deal!

Mike Cason

Discussion Starter · #80 · Dec 6, 2009

Lonely Raven said:
Wow! That's quite a deal!

I'm up to $300 more now with the grillwork and more bolting supplies & silicone. I have more actual money in materials and costs with the twin subs, but I've used them for a couple of years, so I've got my money's worth.

With my work and my wife's work almost at a standstill, I may even put this one up for sale. :hissyfit:

The laminate work is completed and the subwoofer is installed. I'll install the passives, binding post, and lay out the grillwork and may get them built too. Either way, the sub will be done today and in the HT late this afternoon with or without the grills finished.

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