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Re: Maelstrom-21 giveaway build

When I build another box for my Mal-X, I am going to mount it about 1.5 inches behind the front baffle. By that, I mean that it will be flush-mounted, but sunk in 1.5 inches.
That way, you can put a grill cover on it, and flush mount the grill cover also. Otherwise, you would have the grill sticking out about 1-1.5 inches, that way the grill wouldn't hit on the sub during high-excursion movies/songs etc...

Or, you could just make the sub down-firing. I might do that for my next box instead haha. That way, you won't have to worry about little kids poking dust caps, or stuff hitting the sub.
 

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Discussion Starter · #22 ·
Re: Maelstrom-21 giveaway build

That's essentially what I was planning on doing Dylan, building the box so that everything is flush in front and the driver sits 1.5" behind the grill. But instead of sinking the driver I'll be extending the edges of the box. Is there any concern the grill will make noise with 10L of displacement, or is that a non-issue?
 

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Re: Maelstrom-21 giveaway build

Well, then you know what to do:yes:
snicker... dude you RULE! That summs it up as far as I'm concerned... give a 21" room to BREATHE! It will make your walls floor and ceiling breathe right along with it.

If going SLLT, you might also consider a deeper tuning. Try the folllowing in WinISD:
1100 Liters, 11.5 Hz tuning using a 10" port (should be 33.7" long), and a 4th order highpass at 9.6 Hz.
1.1-1.2 kW should be sufficient.
where have you been? ah...only 5 posts.. welcome! I think we will get along just fine.

I think you'd be better with a higher tuning. You give up a lot of headroom for that low tuning.

Sealed can be done, but you will need to get a berhinger feedback destroyer to eq the response you want. I'm not sure aesthetic is happening with a ported monster that size.
Plot a sealed vs the huge low tuned... how much is gained by going sealed vs huge low tuned?

Oh, I'm sorry, I still had the pre-production parameters of the M21 in WinISD.
The actual parameters changed my opinion to 1100 Liters/12.1 Hz with 10" port 30" long (better 11" port 37" long, but I don't know where to get this measure) and approx. 1.3kW.
Tuning to 14Hz might look better in the 20Hz range, but what about room gain?
My simulations, the difference in maximum spl is less than 2dB >20Hz and less than 1dB >30Hz, would it be noticeable?
If I were to power a big concert hall with this sub, i would agree to sub_junkie and choose the 14Hz tuning or even 15Hz, but the target room does not look that big.
Even sealed might be a good option, as the TO already stated, but I would be curious to see him build an SLLT with the M21.
Greetings
RJdaMoD
I agree with you.. what about room gain. However, 2 dB is quite a difference IMHO... 3dB is a doubling.
 

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Discussion Starter · #27 · (Edited)
Re: Maelstrom-21 giveaway build

Okay, I've decided on what type of box I'm going to use. Now I need recomendations on how to power it. The recommended Face Audio amp doesn't work for me because of the gold colour. I may end up going with an Anthem or Paradigm sub amp because I do lots of business with the local dealer. However, I am open to suggestions on other brands, and I do need your advice on how much power I need to use.

I'm building an 8 cubic foot sealed box. Its going to be in a 3500 cu ft room with vaulted ceiling which opens to another 4000 cu ft of house. Its wide open so it's pretty much a 7500 cu ft room. I do play my music loud but my mains
(4 Paradigm Millenia 200's soon to be 300's) will reach their limits well before this sub will, so the sub shouldn't be under any stress. Budget is not a concern, within reason, I'm not going to buy a McIntosh or anything like that. And I do use a BFD 1124p to equalize.
 

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Re: Maelstrom-21 giveaway build

I have just built two ported FI Q18 subs and boy what a result. I nearly bought two mealstroms instead but went for the Q's as they were cheaper. Two ported maelstroms would be mental.

Here's the plot for ONE 12 cu ft ported maelstrom tune to 15hz with 1 20.5" by 2.5" by 45" slot port. 2000 watts running to it and still not exceeding max excursion until 13hz.

Here's a comparison to a single 8 cu ft sealed maelstrom with 1500 watts as it exceed max excursion otherwise.

Guess which is the ported sub?

cheers

Graham
 

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Re: Maelstrom-21 giveaway build

And if your worried about size then here's a 10 cu ft ported sub. Now try to imagine two of these bad boys.

Believe me two ported subs have much more impact than one. I was really surprised how much better the bass sounded. Much deeper and much more sure footed and really clean.

Mmmm Yum Yum.

cheers

Graham
 

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Re: Maelstrom-21 giveaway build

Oops good point.

Here you go with the 21" sub. Both subs with 2000 watts. Sealed not going over max excrusion and the ported not until 12hz.

Guess again, which is the ported.

Tune this to 14.5hz and you will still see a gain with the ported. Unless you are going to listen or watch your stuff at reference you won't need a hpf but even with a hpf you will still be up on the sealed.

The first graph is without a hpf and the second with.

cheers

graham
 

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Re: Maelstrom-21 giveaway build

graham, my friend, I fear this battle and war to be lost. The only way for anyone to grasp the truth is experience. Until they themselves simply try it, all the graphs and plots and verbage will go nowhere. No one is going to stick a port in a box with a 21.

corock, I think you should aim for a 3000 watt amp. The sub I'm told loves 3000 watts... maybe 8 cubes is too large to use all 3000 watts, but that makes room for dynamics...headroom... effortlessness... ease of wear and tear on equipment. I wouldn't sell myself short with just 1000 watts even if plotting suggests it to be all you need.
 

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Discussion Starter · #37 ·
Re: Maelstrom-21 giveaway build

Okay, lets go away from simulation and take a look at some real life results. Here are the measurements for one of my PB-13U's.

First ported and tuned to 15hz
Text Line Plot Slope Diagram

Then sealed
Text Green Line Plot Slope

I'm not using any eq on either of these
Thoughts?
 

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Re: Maelstrom-21 giveaway build

When doing a ported you need to do a slot port to get that size port I quoted and not a round one as it will be long. The 21" sealed is fine in a 8 cu ft box and give a qtc of 0.760. Larger than 8 cu ft will go over max excursion and will lower qtc giving you better low end and smaller box will give you less excursion but higher qtc (tighter bass, less low end). Hence the reason going ported to give you more.

I will drop you some more diagrams tonight but it depends what you want your subs for.

cheers

Graham
 

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Discussion Starter · #40 ·
Re: Maelstrom-21 giveaway build

I use my system for music, movies and tv. Music will be the emphasis of its use though. I like all music, but lean toward hip hop, pop, rap, etc with lots of artificial bass. That's definately what I listen to if I got the volume cranked up.

This build will be about compromise, as is all builds I guess. Aethetics do play a big part of my decision making and I'm not a big fan of slotted ports. From the in-room measurements of my SVS it looks like I'm getting pretty good results down to 15hz out of a sealed box. Sure, the ported box has more spl from 15-20hz but I don't think I'm willing to give up my sealed box design ideas for it.

Kevin H. says not to bother with any less than 2000W to power this thing. The amp has to be black so that rules out the 2700W Face Audio amp. I was thinking of the Behringer EP4000. That's overkill but I guess I don't have to use all that power.
 
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