M-21 Giveaway Build Pics

[sub_junkie]

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.

[corock]

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?

[sub_junkie]

As far as I know, if you get the cloth tight enough around the grill, it shouldn't make noise. But I can't assure you of this

[corock]

sub_junkie wrote:

if you get the cloth tight enough around the grill, it shouldn't make noise.

Sorry, I should have indicated I want to use a metal grill.

[Ryan Anderson]

RJdaMoD wrote:

Well, then you know what to do

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.

RJdaMoD wrote:

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.

lsiberian wrote:

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?

RJdaMoD wrote:

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.

[Mike P.]

7 cu.ft sealed would give you 118 - 120 db at 20 hz with a bit of EQ and room gain, more than enough output for a HT experience.

[corock]

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.

[fackamato]

I don't know if a sealed 21 will be enough for that room. Maybe two ported 18s?

[corock]

oops! I don't live in a mansion. That's cubic feet not sq ft.

[gperkins_1973]

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