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Discussion Starter #1 (Edited)
After alot of reading around and getting great advice from this site in particular I started building one of the two cabinets for my sealed dual sub build.

It will be based on the Maelstrom X 18" and cabinets 61,5cm on all sides, thats 24.21".

I've started building and I am basing my design on other peoples good experiences.

Tomorrow I will cut out the baffels and assemble the rest.

So far so good:





Here's the subwoofer ready to be sent to the painter, won't send until both are completed though. 2 pictures, one with grille frame.



Here's without the grille.



Here's another DIY project that I just finished, I'm planning to give both subwoofers similar finish in white.

 

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Discussion Starter #2 (Edited)
Box is completed. Need it painted now. Also need some fabric for the grilles, they are completed as well, both of them. I've just build the one sub at first, second to follow in a week or so.

I'm gonna post a few more pictures, but my camera isn't really cooperating with my new laptop!

A quick question:


With these enclosure dimensions: ~180 liters = ~ 6.35 cubic feet minus internal bracing which i calculated to be around 6 liters (0.21 cubic feet).

So net internal volume before the driver is ~ 174 liters = ~ 6.15 cubic feet

EDIT: found a post on AVS forum, the driver takes up ~ 0.2 cubic feetså net volume is then 5.95^feet

How much does the driver displace inside the enclosure?

And so here is the real question:

With the net volume given, how much polyfill do I need?

And: is this the right polyfill stuff? http://www.hoejttalerbutikken.dk/product.asp?product=566 (sorry danish site, but you can see the picture and click to enlarge)

My own thoughts on polyfill: I need to raise the perceived volume to around 200 liters to get a QTC of desired 0.7, so I need enough polyfill to gain around 26 liters + whatever the driver displaces. Far off??
Reading off the net I found this rule of thumb: no more than 1 pound of filling / cubic feet enclosure if the enclosure is larger than 3^feet.

Regards

claus linde
 

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Looks great....

I haven't stuffed any of my 3 Mal-X's, but I probably should, so far I do like how they sound.

I look forward to your grill results.... looks like you went 3/4" thick....

Mine flush mounted seem to have a bit more excursion then 3/4", you may want to test before you finalize your design...
 

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Discussion Starter #7
Looks great....

I haven't stuffed any of my 3 Mal-X's, but I probably should, so far I do like how they sound.

I look forward to your grill results.... looks like you went 3/4" thick....

Mine flush mounted seem to have a bit more excursion then 3/4", you may want to test before you finalize your design...
That's a pretty good point, haven't even thought about that. At the moment the grille isn't drilled flush it actually rests with a good 1/2 inch gab from the front baffle.

Maybe that will look ok, having it hover with a small gab from the cube itself.

Never had the excursion of the driver in mind when making that grille!

About polyfill, I'll stuff some in there, according to the theories I've read and the comments I've seen around here. If lucky I can get closer to modelled 200 liter cabinet which should give me a little more buttom end and lower the Qtc to 0.7 or so.
 

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Looks great so far. I am also thinking of finishing my Mal project in white (saw some piano white Totems with black drivers, awesome). When ready, please post some pics of the finished paint job with driver exposed!!
 

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Discussion Starter #11
Thanks!

Ive build box nr 2 - sitting in the workship awaiting drivers.

Since I live in Europe, I need to wait for the distributor to have them in stock :=)

I'm contemplating building an even smaller cabinet, purely as a test - then make some measurements in room, using both.

Since I have some time before drivers can be delivered I can easily build another cabinet.

I like building anyways :)
 

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Discussion Starter #13 (Edited)
Lastest news is that the swedish distributor will have them in stock in late july.

I havent started construction of the 100L box yet, but I have 2-3 months before the drivers arrive so should give me plenty of time to do that.

Would it be fair to include polyfill in the modeling process? I mean if I build 95L and gain 15% with poly? ~ 110L+ then subtract the driver and bracing ending up with around 100L

Just wanted to let you all know this project is still going, just that I am waiting for the drivers.

Meanwhile I'm surfing the net looking at everyone elses wonderful subwoofer projects!
 

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Discussion Starter #14 (Edited)
Question about power for 2 18" maelstrom x in these 175L boxes.

I was planning to start out with just one EP2500 however I just found some nice prices on the EP 4000.

Here are the specs:

EP2500:
2x 750watts at 4ohms, 2x 500watts at 8ohms, 2x 1200watts at 2ohms, bridged 1x 1500watts at 8ohms, 1x 2400watts at 4ohms

EP4000: http://www.behringer.com/EN/Products/EP4000.aspx
2x 1400watts at 4ohms, 2x 750 W @ 8 Ohms, 2x 2000watts at 2ohms, 1x 2800 W @ 8 Ohm, bridged 1x 4000 watts at 4ohms

Pricedifference is: 67 dollars between the 2.

Question is: Will I end up with 2 amps eventually or will one EP4000 be enough for both drivers you think?

OR will 2 EP4000 in the end be ultimately better?:)
 

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Hey Claus, we haven't actually seen measurements yet, but its a good possibility that the EP4000's are just rebadged EP2500, but time will tell for sure, unless I missed someone doing some real world measurements of them already...

I have 3 Mal-X's sealed, and I am powering them with Crest 8002's each..... 4000w bridged, when you add the EQ boost to the Mal-X's, they will require a good deal more power then the EP amps can deliver, and you will end up clipping.

Keep your eyes open for some used 4000w amps like the Crown CE4000's, you won't be dissapointed with going bigger, I have 3 2500w amps laying around that I will need to sell now because I didn't think I would need this kind of power...

Unless you have a small - medium/small size room, I would be looking for a big amp for each one if you can afford it...
Another thought would be a QSC 3402 or something in that range
 

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It is confirmed that EP4000 is a rebadge of the EP2500. Same amp. Credible people have opened the EP4000 up and looked inside. Still a good one for the price.

Clausdk,

Go for 2 EP2500's one for each driver, or better yet some of the amps that Warpdrv mentioned.
 

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Discussion Starter #17
Thanks for the great advice.

I've looked over the prices new and used for both Crown and QSC and even used just one crown is the price of 2 new EP 2500 for me.
Might have 2 used QSC 3402 though. I send a mail inquirering about it, so I should know about it soon. Will still be more expensive than 2 EP2500, but not much, depends on what price I can get, used.

My room is 2500 cubic feet.

EP 2500 x 2 seems like very good value it's still. I can buy directly from germany and really get a very good price.

When modelling the performance using WINISD using 185 liters and inputting 1200w it show near xmax at 20hz, so EQing that area 3 db for instance then exceeds xmax.

So am I modelling incorrectly? or is 1200w not enough?
 

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I am running the Same boxes and drivers, are you applying EQ boost down low around 20hz, which will give you a flat response? I haven't modeled them for a while, and frankly I don't care what the model says, when I boost down low with EQ and runn the EP2500 full boar - I get clipping...

But remember I asked how large your room was, Mine is stupid big, so chances are that I have to push mine much more to get the SPL I like, which is usually more then most....

I would opt for the bigger amp, as they are so clean and I really like to push them... but that me...
 

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Discussion Starter #19
Very much appreciate you sharing your actual practical results. They tell us alot more than any theory might :)

As this is my first DIY project I think I will "settle" for 2 EP2500 which can be had for a 1/3 -1/4 of the price of any of the other amps.

As far as I can tell from reading around two maelstrom x in a reasonable sized closed box with each of its own EP 2500 will rock my 2500 cubic feet living room:)

If I find that it will be insuffecient, and economy allowing it, I can perhaps upgrade the amp down the line.

Warpdrv, do you have any in room measurements? I mean, how much SPL are you getting in your setup?
 
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