[Kevin Haskins]

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

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

 

[Kevin Haskins]

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

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 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.

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

VBR
Mike

Hey... no problem. I love getting people pointed in the right direction. You can use as much power as you can afford on this driver. I have several people using 3000-5000W worth of amplifier (ratings) and there is not an issue with using "too much" power. They eat it up.... and what you get out of the wall usually limits what you put into the driver anyway.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

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

Thank you for that Mike,

I always love those lower numbers. I was thinking the larger cabinet may be a benefit.

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 15's or 18's; or Kevin's passives. John's have a much lower fs of 5 which is good. I may ask you to explore which one you would use, either three 15's or 2 to 3 18's. I wouldn't want you to spend any time on it until after I get cash in hand tomorrow night.

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

It looks small in that picture.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

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

Great Build! With the box size stay the same if you went with 18" pr's instead of 15's and would that buy you anything? Would you be able to use few pr's if the 18's were used? I ask because I may want to build one myself.

Sure.... you can build around 7 cubic feet with a single M-18 & a pair of PR-18s. It is still a house-wrecker.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

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

what I mean to say was how would the 21" do with 18" passive radiators? Didn't I see a thread somewhere about some 21" pr's?

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

 

[Kevin Haskins]

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?

I wouldn't.... as much as your spending on a subwoofer, I'd get the SMS-1 so you have room measurement and EQ capability. There is no sense spending that much on a subwoofer and not having it.

Once you have that.... Denon RCA Output --------> XLR SMS-1 XLR --------> XLR Face Amp

How long have they been around and what is the RMA rate of these amps?


Mike

Good question.... I don't know. I've never had one of them returned outside of an audiophile that didn't like the fan noise. Face is relatively new, but well run and they stand behind the product better than most companies I've had to deal with. They are a good company, otherwise I wouldn't bother with them.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

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 Perioria 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

I've not had a chance to hear every model by any stretch but most of the pro-sound amps I've been around, all have similar noise levels. I wouldn't count on it being any better or worse than another brand.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

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 will be the Maelstrom 21" subwoofer instead of the one pictured on the left when I'm done.

Mike,

They are a good company, I like doing business with them and they have been excellent anytime I've needed them. They get top-marks from me.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

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

 

[Kevin Haskins]

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

 

[Kevin Haskins]

I just think i did it right choosing the shack forum, after a year or so reading anonymous in diy forums.

Mike It should have been this way around with the sub, and i am glad to hear it, as larger objects are brought into resonance like windows and with this sub the walls and even the larger of all the mother earth under you yourself.

I know i should have posted that in a new thread but I found today something that worries me though, it is about the little brother of this one – the Maelstrom 18”, please take a look at that, the guy complains he bottoms it out easily when playing frequencies 20 to 30Hz
The link http://www.hometheatershack.com/forums/exodus-audio/20266-7-6-cu-ft-maelstrom-x-18-build-9.html

And my comment on that issue was:

“
Dudes, on the bottoming out the sub ..

I have dayton reference sub Dayton RSS265HF-4 (and I know how this noise is being produced), to reach it I press the cone down with my bare hands to its suspension limits, but carefully and with old subs I reach that . With Hertz and Daytons I have, I do not reach that point at all, where voice coil former hits the pole piece. So sad for such a pumped with muscle sub

(No doubt dayton will reach its excur. limits earlier than the Maelstrom, but never with "nocking noise")

”

The whole here resembles old motor/ voice coil designs as i came across this issue with old subs long time ago. I still think the bottom limmiting factor of a sub cone excursion (as well the upper constraint) should be only the suspension, not the hit between the voice coil former and the pole piece. How do you think, guys is it a concern, ohh:doh: almost forgot this effect is captured on camera found it in youtube, here, notice what happends between second 39 and 41 (then the guy decreases the volume/power to it):

http://www.youtube.com/watch?v=xIKfkzygw7Y&NR=1

That is not a hit between the former and the pole. It is the suspension running out usable throw and soft limiting.


Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

I beat the snot out of my 21" with movies, and pushed the limits to take some videos for the guys here, and the worst I got was a little wump-wump-wump sound of the suspension at 3Hz with an EP2400 maxed out. So it was difficult to get my sub to "make noise". Otherwise it's been a smooth beast that just seems to get better with age.

Free air with lots of power is a different story.

In a box, you need a massive amount of power to hit those limits. In most real-world conditions the power line is sagging at that point and amplifiers are not delivering full gusto.

I should take a destructive testing video and post it up there. I beat them to death testing early production units and it is very entertaining. Most guys love to break things and I'm no different. I cringe as the things go whack-whack-whack-whack until something lets loose. I've been able to smack a back plate on a Shiva & Tempest once the suspension lets loose but I've never seen a Maelstrom either the 18" or 21" hit even in destructive testing.

Kevin Haskins
Exodus Audio

 

[Kevin Haskins]

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

 

[Kevin Haskins]

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