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

57961 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

See less See more

81 - 100 of 181 Posts

sub_crazy

· #81 · Dec 7, 2009

I have been busy lately so not much time to look around the forum...........Glad I caught this!

Great build, can't wait to hear how it compares to your previous build.

Mike Cason

Discussion Starter · #82 · Dec 7, 2009

sub_crazy said:
I have been busy lately so not much time to look around the forum...........Glad I caught this!

Great build, can't wait to hear how it compares to your previous build.

I received a delightful email from the buyers from Peoria Illinois of my stacked pair of subs in my avatar, and they simply can't believe the quality. They have done some eq and 15 hz is no problem with them and they hear everything so clearly in the below and above 20 hz frequencies, and at db levels never heard before. They are astounded! Why was I so stupid to get rid of them to build another one? They also have some expensive subs they are gettin rid of now!

Well the Texas Monster is finished as of 5 minutes ago. I'll get the pics to the computer and show you guys what I've built now!

Mike

Drizt

· #83 · Dec 7, 2009

Can't wait to read your thoughts on them once they are all set up properly

Mike Cason

Discussion Starter · #84 · Dec 7, 2009

Hey Mr. Raven:

Here are the completed pics. I plan on making nice grills, but I have all week to do that. At least these qaulify for the first completed build of the Maelstrom 21s!! :T They don't have to have grill covers to qualify.

Pardon the spots on the camera lens. I need to take the time to properly clean it to get rid of those dirty circles and spots.

I've got just barely enough room to get a nice grill beside the 21" beast. I've framed it already.

The first pic show just how large that driver is compared to the 18" passives on the sides. They look like 12"ers!!

The next shot shows the passives with my huge binding post for extra large speakers. The binding posts will accept bannana plugs, terminals, or #4 wire.

The third shot is from the side before I installed the passives showing my "basket made out of stretched audio grill cloth" and full of polyfill properly secured to the top of the cabinet. It also shows some polyfill on the bottom and the construction of the rear of the opposing radiators. I have Sonic Barrier on the top and the bottom of the cabinet, just because it was left over stock. It may provide some standing wave reduction, and with this cabinet, I don't think it will have a resonating problem? If so, the Sonic Barrier should handle that.

The fourth picture is a repost that shows the intricate details in construction before the laminating.

I got rave reviews on the Black Slate Pionite laminate from the buyer of my two stacked subs, and with a little application of Armorall once in the house, these should really shine. :wave:

It's late and raining, so I'm not going to attempt to get it inside tonight. Hopefully I'll have it online in my L/R HT and have a report by tomorrow afternoon. I've got a day's of bookwork to do too. I have Linkwitz's tone CD and a bass test cd, so I'll see if the graphs properly represent the 15.5 & 16 hz box tuning shown in the graphs. I really need to run some pink noise through them for a couple of days too, and then re-measure the tuning.

Yall have a great evening!

See less See more

4

Lonely Raven

· #85 · Dec 7, 2009

Great work! It's good to see someone using laminate in the forums. I keep suggesting it to people who want a "piano black" finish, but nobody has taken up my suggestions so far. I've used it before on subs with great results, but I'm a bit rough on them (they tend to get moved a lot), and laminated corners don't last long with me. Otherwise I'd be seriously considering it for my M-21 as well.

I'm looking forward to seeing how you feel about them in action. I'm already wanting a second one in my setup, as I love how much air it pushes.

Mike Cason

Discussion Starter · #86 · Dec 8, 2009

Re: First report....

I managed to wheel it into the house last night. It didn't take up much more room than the stacked subs, but I don't have any grills made which will make it 4" wider.

Bass??? After discovering my Denon 5308CI had lost all of it's settings, I finally got the Face 1200 to start throwing out some signals.

I was very concerned about a 21" woofer from comments from the unbeleivers. Comments like the driver that size isn't quick enough to give you good bass & so on. You don't see 21" subs in the marketplace either. I think Foxtex has a $2,200 31" and a couple of others may offer something similar, but I've never heard of one finished in retail. If they would be that great, we should see more of them.

Well the Maelstrom breaks the barrier to lower bass, cleaner bass, and lots of both in the 21" driver!

The XBL2 motor design plays a big part in its superior performance.

I wasn't in the position to take some measurements but I did listen to a couple of test THX & Dolby Digital DVD tracks, Santana at Montreaux, and then the ultimate test; John Clayton's stand up bass on Diana Krall's live in Paris DVD. Of all the subs I've built and owned, including Legacy's infamous Point One, Mr. Clayton's bass has always produced a bunch of resonance. This disc is the only one that does that in my collection. Sure, I could probably go out and buy a multi-band equilizer and get rid of the unwanted resonance, but I wanted a sub that would play every note as John played it. I stuck the disc in the OPPO and hit the play button and was probably as nervous as Susan Boyle's debut when they pushed the play button.

Their opening song is probably their best on this album with John Clayton's bass, their lead guitarist, of course Diana's piano playing.

The sub didn't have any distortion, a total lack of resonance, was crystal clear, and with John plucking the bass strings, it sounded like you were there or he was here. The second track had John's bass playing as well and all was good. I was/am very impressed. I'm sure the 4 2100 gram passive radiators played a huge role in the performance as well as the properly built and dampened cabinet. With my new Denon flagship receiver, the picture was upconverted to 1080p, so I watched the concert until the wife went to bed. I haven't watched this DVD with my new receiver and its new HQV upconversion chip. It upconverts everything including Direct TV and component video.

When she got home, she locked the electric gate (we have a chain we use for added security). When she came in the house I told her how great it performed and she said the fence and gate was ratteling and I didn't even have it up to the spl I really like listening concerts at.

I've got a lot of shop, truck cleanup, and paperwork to do, but I'll find the tuning frequency and some spl levels in the next couple of days. I used the Face 1200 and got it to clip a couple of times (on purpose for testing). When I had it cranked up during some of the test cd tracks, the driver was really moving.

I guess by this report you guys know well I like it! It gets an 11 point rating out of a possible 10.

See less See more

Lonely Raven

· #87 · Dec 8, 2009

Sounds GREAT Mike. Your thoughts on it really pick up where mine left off. I can tell you all about movies and impact and dynamics, but your thoughts on upright bass is even more impressive! I couldn't think of anything in my collection that I could test that has bass like that...except maybe some Miles Davis now that I think about it.

Mike Cason

Discussion Starter · #88 · Dec 8, 2009

Lonely Raven said:
Sounds GREAT Mike. Your thoughts on it really pick up where mine left off. I can tell you all about movies and impact and dynamics, but your thoughts on upright bass is even more impressive! I couldn't think of anything in my collection that I could test that has bass like that...except maybe some Miles Davis now that I think about it.

On my test DVDs, I had some movie scenes like Ants, Starwars, The Haunting, The Astronaut, and others. The impact scenes on those movie tracks couldn't be any better.

I think for any home theater use, a single 21" Maelstrom is all you need if your cabinet is constructed well and dampened properly. My L/R is 20 x 24 with 9' ceilings, opening up to the kitchen pass thru and wide open to the dining area so we can watch tv at the dining table. I think if you were to properly build two subs with a driver of this size and capability, you would have to turn the gains down to 1/2, thus defeating the use of two 21" subs. Bass is great, but you also need to hear the voices and movie as well. A very large HT may benefit well by having two of them.

Kevin Haskins

· #89 · Dec 8, 2009

Mike Cason said:
On my test DVDs, I had some movie scenes like Ants, Starwars, The Haunting, The Astronaut, and others. The impact scenes on those movie tracks couldn't be any better.

I think for any home theater use, a single 21" Maelstrom is all you need if your cabinet is constructed well and dampened properly. My L/R is 20 x 24 with 9' ceilings, opening up to the kitchen pass thru and wide open to the dining area so we can watch tv at the dining table. I think if you were to properly build two subs with a driver of this size and capability, you would have to turn the gains down to 1/2, thus defeating the use of two 21" subs. Bass is great, but you also need to hear the voices and movie as well. A very large HT may benefit well by having two of them.

Oh come on Mike, everyone needs at least FOUR 21" subwoofers. ;-)

I'm glad it turned out so well for you. Be careful with test signals near the tuning frequency of the PRs. Once the drivers stops moving, it loses most of its ability to shed heat so that is a very easy area to smoke a voice coil with test signals.

Kevin Haskins
Exodus Audio

Mike Cason

Discussion Starter · #90 · Dec 8, 2009

Kevin Haskins said:
Oh come on Mike, everyone needs at least FOUR 21" subwoofers. ;-)

I'm glad it turned out so well for you. Be careful with test signals near the tuning frequency of the PRs. Once the drivers stops moving, it loses most of its ability to shed heat so that is a very easy area to smoke a voice coil with test signals.

Kevin Haskins
Exodus Audio

Oh yea....I forgot....one 21" sub in each corner of the HT will drive out all of the termites, thus saving you thousands of dollars in future repairs!

Thanks for the reminder. Linkwitz's CD only gives me 4 or 5 short bursts and that is why I use it.

Years ago I did happen to blow four of Dan's Adire passive radiators out after I hit the wrong button. It sounded like a train engine coming apart! Weights were being thrown off the backs of the passives and hitting the sides and the passive radiators opposite them. I had the amp cranked up and I was trying to hit a high hz frequency tone signal for some reason, but I hit the wrong button on the controller.

I bet anyone in here that has been building speakers for a while has done something like that once or twice!

onder:

Thanks for an excellent product. :T

Mike

See less See more

sub_crazy

· #91 · Dec 8, 2009

Awesome to hear it is working out so great for you:T.........lousy for us who don't have a M-21 and are insanely jealous:hissyfit:

I thought an M-18 would satisfy my bass rage paired with a bunch of other subs but now Kevin ups the ante even further. Kevin is my pocket books mortal enemy:boxer:

Ryan Anderson

· #92 · Dec 8, 2009

Re: First report....

Mike Cason said:
I managed to wheel it into the house last night. It didn't take up much more room than the stacked subs, but I don't have any grills made which will make it 4" wider.

Bass??? After discovering my Denon 5308CI had lost all of it's settings, I finally got the Face 1200 to start throwing out some signals.

I was very concerned about a 21" woofer from comments from the unbeleivers. Comments like the driver that size isn't quick enough to give you good bass & so on. You don't see 21" subs in the marketplace either. I think Foxtex has a $2,200 31" and a couple of others may offer something similar, but I've never heard of one finished in retail. If they would be that great, we should see more of them.

Well the Maelstrom breaks the barrier to lower bass, cleaner bass, and lots of both in the 21" driver!

The XBL2 motor design plays a big part in its superior performance.

I wasn't in the position to take some measurements but I did listen to a couple of test THX & Dolby Digital DVD tracks, Santana at Montreaux, and then the ultimate test; John Clayton's stand up bass on Diana Krall's live in Paris DVD. Of all the subs I've built and owned, including Legacy's infamous Point One, Mr. Clayton's bass has always produced a bunch of resonance. This disc is the only one that did that in my collection. Sure, I could probably go out and buy a multi-band equilizer and get rid of the unwanted resonance, but I wanted a sub that would play every note as John played it. I stuck the disc in the OPPO and hit the play button and was probably as nervous as Susan Boyle's debut when they pushed the play button.

Their opening song is probably their best on this album with John Clayton's bass, their lead guitarist, of course Diana's piano playing.

The sub didn't have any distortion, a total lack of resonance, was crystal clear, and with John plucking the bass strings, it sounded like you were there or he was here. The second track had John's bass playing as well and all was good. I was/am very impressed. I'm sure the 4 2100 gram passive radiators played a huge role in the performance as well as the properly built and dampened cabinet. With my new Denon flagship receiver, the picture was upconverted to 1080p, so I watched the concert until the wife went to bed. I haven't watched this DVD with my new receiver and its new HQV upconversion chip. It upconverts everything including Direct TV and component video.

When she got home, she locked the electric gate (we have a chain we use for added security). When she came in the house I told her how great it performed and she said the fence and gate was ratteling and I didn't even have it up to the spl I really like listening concerts at.

I've got a lot of shop, truck cleanup, and paperwork to do, but I'll find the tuning frequency and some spl levels in the next couple of days. I used the Face 1200 and got it to clip a couple of times (on purpose for testing). When I had it cranked up during some of the test cd tracks, the driver was really moving.

I guess by this report you guys know well I like it! It gets an 11 point rating out of a possible 10.

BRAVO! BRAVO!

Drizt

· #93 · Dec 8, 2009

Thanks for the report. You can just sense your overwhelming enthusiasm which is great stuff.

sub_junkie

· #94 · Dec 9, 2009

Kevin Haskins said:
Oh come on Mike, everyone needs at least FOUR 21" subwoofers. ;-)

Kevin Haskins
Exodus Audio

Oh...I'll gladly try out four 21" subs in my 13x13 room for no charge :hsd:

Simply send them and a few of those super fancy Face Audio amps that you have there, and we have a deal :bigsmile:
lol just kidding.

It's good to hear that everything turned out awesome Mike. Excellent build to. I wish I could have a 21" to match my Mal-X :T But, I'm too poor...a 15 year old in this kind of audio stuff...you tend to run out of money pretty quick haha

Jason_Nolan

· #95 · Dec 9, 2009

Any graphs?

Mike Cason

Discussion Starter · #96 · Dec 9, 2009

Jason_Nolan said:
Any graphs?

Yes, see post #5. Kevin Haskins did a nice job. I expect a little lower tuning with my 4 18" 2100 gram prs, but it is close.

I may be forced to sell this one with grills completed and the amplifier due to finances. I've got an order of drivers coming in from China and money is tight. Both of our main jobs came to a standstill but the bills haven't. I'll make that decision soon.

Mike

Mike Cason

Discussion Starter · #97 · Dec 9, 2009

sub_junkie said:
Oh...I'll gladly try out four 21" subs in my 13x13 room for no charge :hsd:
Simply send them and a few of those super fancy Face Audio amps that you have there, and we have a deal :bigsmile:
lol just kidding.

It's good to hear that everything turned out awesome Mike. Excellent build to. I wish I could have a 21" to match my Mal-X :T But, I'm too poor...a 15 year old in this kind of audio stuff...you tend to run out of money pretty quick haha

I'm proud of you for taking up this hobby son. There are so many other 15 year old's out there taking on hobbies that lead them down the wrong road. You are in a forum with a bunch of great guys and we'll support you all that we can.

Mike

Lonely Raven

· #98 · Dec 9, 2009

Well said, Mike!

Mike P.

· #99 · Dec 13, 2009

Any pics of the sub in house?

Mike Cason

Discussion Starter · #100 · Dec 13, 2009

Mike P. said:
Any pics of the sub in house?

I thought about that yesterday. It looks so much nicer in the home than in the garage. I've been very sick but am better, so I'll get a couple posted later on when I've been up a while. I need to clean the camera lens first.

.....I watched Celtic Women on local antenna yesterday and the subwoofer hit lows I've never heard out of a sub, ever! I just happend to be in the back room when that particular song played. I walked into the LR and was extremely wowed by the low earth shattering bass it was producing at a low volume. It was simply incredible and unbeleivable! :hsd:

81 - 100 of 181 Posts

This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.