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

57977 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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161 - 180 of 181 Posts

Mike Cason

Discussion Starter · #161 · Feb 3, 2010

dyohn said:
You might want to start a new thread in the DIY Speakers section for your new build...

Hi Dyohn,

I made mention of doing that in my post....Thankx

dyohn

· #162 · Feb 3, 2010

Mike Cason said:
Hi Dyohn,

I made mention of doing that in my post....Thankx

Cool, looking forward to it!

BTW, I once built a center channel for a client that incorporated dual 10" powered subwoofers...

Mike Cason

Discussion Starter · #163 · Feb 4, 2010

dyohn said:
Cool, looking forward to it!

BTW, I once built a center channel for a client that incorporated dual 10" powered subwoofers...

I hope they were pleased, or I should say, I know they were pleased.....That's much better...

Here is my new build thread:

http://www.hometheatershack.com/for...0-kevlar-center-speaker-build.html#post232858

Mike Cason

Discussion Starter · #164 · Feb 4, 2010

sub_junkie said:
A center channel with 10" woofers???? Are you crazy man?! :coocoo:

YEP....

Mike Cason

Discussion Starter · #165 · Feb 6, 2010

Mike P.

The Maelstrom 21" Ultimate 1.1 is finally completed.

You are leaving your ideas worldwide in and on all sorts of locations.

Thanks, :T
Mike

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Drizt

· #166 · Feb 28, 2010

Hi Mate,

Did you ever get to take any REW measurements of this beast ?

Mike Cason

Discussion Starter · #167 · Feb 28, 2010 (Edited)

Drizt said:
Hi Mate,

Did you ever get to take any REW measurements of this beast ?

I'm not set up to take measurements. If I were selling a finished product line, then I would set up one of my computers with the software to do so. I have a lot of projects to do already. I can tell you that it re-produces anything you throw at it quite well and without distortion.

In an earlier post, Kevin has a very nice graph modeling some 15" passives (I think) instead of the 2100 gram 18s I'm using now. Projected output 120 dB at 20 hz? Mike P. has also done a nice graph which projects about 118 db at 20 hz. Sprinkle in some room gain with 9' ceilings and you end up with a whole lotta bass! :hsd: I'm driving it with 2719 watts of high current torrodial power.

Cheers my friend,
Mike

sub_junkie

· #168 · Mar 1, 2010

Mike Cason said:
In an earlier post, Kevin has a very nice graph modeling some 15" passives (I think) instead of the 2100 gram 18s I'm using now. Projected output 120 dB at 20 hz? Mike P. has also done a nice graph which projects about 118 db at 20 hz. Sprinkle in some room gain with 9' ceilings and you end up with a whole lotta bass! :hsd: I'm driving it with 2719 watts of high current torrodial power.

Cheers my friend,
Mike

You can put 2700+ watts through will no problems? Even at the tuning requency, the passives won't have any distortion? That's impressive.
I hope I can experiment with some passives soon. But, the AntiMode offered a better improvement for my room (at least I hope...lol) so I went with that instead of the passives.

Mike Cason

Discussion Starter · #169 · Mar 1, 2010 (Edited)

sub_junkie said:
You can put 2700+ watts through will no problems? Even at the tuning requency, the passives won't have any distortion? That's impressive.
I hope I can experiment with some passives soon. But, the AntiMode offered a better improvement for my room (at least I hope...lol) so I went with that instead of the passives.

Each of the 4 passives have a 3" P to P excursion. I would never, nor have the need to drive the sub that hard, but it is nice to have the reserve power in the amp to hit the occasional slams and deep bass when it is needed. I always like to have more power than needed. It's kinda of automobile setups with the extra capacitors mounted in the trunks that are able to hit the drivers with more power when they are needed, or like a truck with a much larger engine than needed for normal use. It's there when you need it though. The amp doesn't work as hard which reduces or eliminates clipping and provides cleaner power.

No, I've never heard distortion with anything I've ever played through it yet. Sorry ya didn't win the contest... :foottap:

Kevin Haskins

· #170 · Mar 1, 2010

sub_junkie said:
You can put 2700+ watts through will no problems? Even at the tuning requency, the passives won't have any distortion? That's impressive.
I hope I can experiment with some passives soon. But, the AntiMode offered a better improvement for my room (at least I hope...lol) so I went with that instead of the passives.

Putting 2700W into ANY transducer with a test signal at the tuning frequency of either a ported or PR system is going to smoke it. Read the Power Handling Sticky.

Kevin Haskins
Exodus Audio

Mike Cason

Discussion Starter · #171 · Mar 1, 2010

Kevin,

Agreed!

Either in one of my posts or pms, I asked you about the noise level of the Face 1200 amp vs the QSC or Crown. Two things to note here. After using the QSCs for several years, I find the Face Audio amplifier to be a much better sounding amplifier. #2, I don't hardly even hear it. It is inside my equipment rack with a glass front and unless I'm driving it hard, then stopping to listen for the fans, I may barely hear them only for a few seconds then they are quiet. During normal to reasonably loud playbacks of music and movies, I don't hear a thing. They are sooo much quieter. You told me you had nothing to compare them with, so I wanted to pass this good information along to you.

Mike

sub_junkie

· #172 · Mar 1, 2010 (Edited)

Kevin Haskins said:
Putting 2700W into ANY transducer with a test signal at the tuning frequency of either a ported or PR system is going to smoke it. Read the Power Handling Sticky.

Kevin Haskins
Exodus Audio

At tuning frequency, the driver looses its ability for cooling due to the reduced excursion (or just plain overpowering the driver), which results in the said bad smoke if driven that way for too long. I've read it before, and I thank you for posting it :bigsmile: :T

Mike Cason

Discussion Starter · #173 · Mar 1, 2010

sub_junkie said:
At tuning frequency, the driver looses its ability for cooling due to the reduced Xmax (or just plain overpowering the driver), which results in the said bad smoke. I've read it before, and I thank you for posting it :bigsmile: :T

SJ, You are correct.....

When I test my cabinet for the tuning frequency, I watch for the driver to stop, and the passives to move a lot. My test CD is the Linkwitz Riley frequency CD which has short bursts. I also have some other test CDs but this is my favorite so I don't put a load on the voice coil and the lack of cooling at box tuning. The short bursts provide that level of protection.

fackamato

· #174 · Mar 1, 2010

sub_junkie said:
At tuning frequency, the driver looses its ability for cooling due to the reduced Xmax (or just plain overpowering the driver), which results in the said bad smoke if driven that way for too long. I've read it before, and I thank you for posting it :bigsmile: :T

xmax is constant, it never changes. You probably mean cone excursion, and yes that is reduced at tuning. :T

sub_junkie

· #175 · Mar 1, 2010

Mike Cason said:
SJ, You are correct.....

When I test my cabinet for the tuning frequency, I watch for the driver to stop, and the passives to move a lot. My test CD is the Linkwitz Riley frequency CD which has short bursts. I also have some other test CDs but this is my favorite so I don't put a load on the voice coil and the lack of cooling at box tuning. The short bursts provide that level of protection.

If I ever run test tones, it is only for a short time to. I don't want to risk damaging the driver, or my hearing

sub_junkie

· #176 · Mar 1, 2010

fackamato said:
xmax is constant, it never changes. You probably mean cone excursion, and yes that is reduced at tuning. :T

I noticed that right before I read your post lol. Thanks for spotting that :T

Kevin Haskins

· #177 · Mar 1, 2010

fackamato said:
xmax is constant, it never changes. You probably mean cone excursion, and yes that is reduced at tuning. :T

Most of the heat that is dissipated by the coil (>80%) is removed from the coil/former to the atmosphere by air passing over the coil. If you don't have any air passing over it then it quickly will make stinky smoke.

Think of a computer CPU. Imagine for a second you have a heatsink/fan on a high-power overclocked CPU. Now stop the fan. How long will that CPU last before it goes up in smoke? It is the same for any device that is air cooled primarily via convective heat loss as the dominant form of heat dissipation.

Kevin Haskins
Exodus Audio

ddn13

· #178 · Mar 16, 2010

great project! compliments

Mike Cason

Discussion Starter · #179 · Mar 16, 2010 (Edited)

ddn13 said:
great project! compliments

ddn13,

Thanks....After a couple of months of break in time and listening to music and movies, I would venture to say that this subwoofer is as good or better than any subwoofer offered in the retail or high end markets, including the Wilsons and others. The musical quality of this subwoofer/passive radiator combination is extremely clean, smooth and low. Movies are absolutely stunning! I just don't know how it could possibly be any better....period......

My hat is off to Kevin for such a magnificent product and service.....:fireworks1:

dusnoetos

· #180 · Jun 1, 2010

WOW, I must say that this is one sweet build. Reminds me of one of my first subs I build for someone else (sure wish I had not lost the pictures of it...). It was a single large horn loaded enclosure with 4 18" Aura 1808 drivers. It had painfully loud bass output but I doubt it sounds any were as good as your build sounds. Then again I built the sub for a mildly popular local thrash metal band.

One question for you..
what kind of Crossover did you build or use to mate these monsters with your mains?

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