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Discussion Starter · #1 ·
Within the last hour I received my Maelstrom X (DHL). The box was fairly beat-up, but upon initial inspection, the driver seemed unharmed, (and pretty amazing). Thanks Kevin.

I now have my Maelstrom X, my EP2500, and many sheets of MDF. I am ready to get started, but need some further input.

In regards to the enclosure, I am planning on building a sealed enclosure (smaller enclosure, easier WAF). There have been two sealed designs suggested thus far that I have seen, Kevin Haskins' (21" x 24" x 22" ~ 6.41ft^3 ~181.51 Liters), and Dan's (24"^3 = 8ft^3 ~ 226.53 Liters). Obviously, this is Kevin's product, so I trust his design fully, but Dan's design would be so much easier to build. Would the performance be much different/or better in either suggested enclosure when compared? The sub will be powered by an EP2500. Would a BFD be helpful/needed/worthwhile?

As for internal wiring, should the 8ohm DVC's should be wired in parallel producing a 4ohm load and should be powered by 1 channel of the amp for optimum (vs. wiring each voice coil to it's own channel on the amp)?

Internal speaker wire: 10 0r 12 gauge wire?

Suggested mounting hardware for driver?

Is a subsonic filter needed to protect the driver using the EP2500 in the above configuration?

Lastly, do you all have any other thoughts or suggestions? Any suggestions/advice would be greatly appreciated (measure twice, cut once).

Thanks,
DCartes
 

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I’m not a sub pro but I’ll throw in my $.02 because I have a similar build in mind...

What matters for the box you build is actually the internal volume of the box (minus bracing, and the volume that the driver takes up). I saw Kevin Haskin's design and I am guessing that the internal volume is around 4 cubic feet. The only reason I mention this is that the external dimensions of a subwoofer box can be misleading depending on the thickness of the box walls and extensiveness of internal bracing.

I’d recommend that you wire the voice coils in parallel and then run the EP2500 bridged into the resulting load. That should give you around 1500 “real” watts (depending on several factors).

Going back to the box size: according to Winisd, it looks like you won’t need a subsonic filter if the sealed box is around 4 or 4.5 cubic feet. That’s what I plan…for now…

As for the other questions: a BFD would probably be helpful although it depends on your room and placement (you could also do research on creating an L/T with a shelving filter with a Behringer DCX2496 or DEQ2496), I plan on using 12 gauge wire internally, and hurricane or t-nuts for mounting

Other advice: I highly recommend doubling up the front baffle for a woofer this size and with this much power. Hope that helps…
 

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Discussion Starter · #3 ·
Thank you ThatGuy for your timely and informative reply. I have a few follow up questions.

So you suggest a 4 or 4.5ft^3 sealed box (net or gross, after subtracting out bracing and driver volume)?

Also, should you flush mount the driver? If so, do you need to triple the front baffle so that the driver is mounted on to two complete thicknesses of MDF (the outer being mostly cosmetic)?

Thanks again for all of your suggestions. I can't wait to get started!

DCartes-
 

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I am going to go with 4.5 cubic feet and that's minus all bracing and driver volume (I'll have to guesstimate on the driver volume).

I'd say you're good with the 2 layers of MDF for the front baffle...even if the woofer is flushmounted and screwed into one baffle with enough glue the two baffles are still working together.

Glad I could help but wait and see what others suggest, too!
 

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I pretty much agree with what Thatguy said. The volume of the box is what is important and, as long as it is properly braced, the shape doesn't really matter. And the listed volume is minus all bracing, the amp, the driver, etc. Just the empty space. Flush mounting is a matter of personal taste - in subs the wavelengths are long enough it won't sound any different.

I also give a big +1 on the BFD. All rooms have room modes and with a nice driver like this you'll really want to flatten them out. Also, on a sealed sub there is a good chance you'll want to tweak the low end a bit.

As far as what volume to use I suggest running Unibox or WinISD for your driver in various volumes. This way you can see how FR and excursion change yourself. Not only will you end up building what you want but you'll learn something too. How fun! :bigsmile:
 

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Discussion Starter · #6 ·
I wanted to say thanks to all of you who helped me with suggestions and input for my Maelstrom-X sub build, especially to Army, 1080c, and Kevin Haskins. It's certainly nothing special to look at, and I have yet to hook up my EP2500 and fire everything up, but I should be up and running tomorrow.

As for specifics, the sub is 22" cubed (internal) ~ 6.16 ft^3, (not accounting for bracing and driver volume). There is one cross-brace parallel to the doubled up front baffle, as well as smaller side braces reinforcing the rear panel of the box. The box is stuffed with roughly 80 ounces of polyfill. The driver is wired in parallel, and will be run off the EP2500 bridged. I haven't decided on a finish for the box yet. I have filled and rough sanded the box though.

A few side notes - I initially thought that I would flush mount the driver, only to find out that my Jasper-Jig isn't capable of cutting an 18 1/2" hole. I didn't have the patience to build a jig, so I just mounted the driver to the outer baffle. I also purchased 1/4 20 allen head bolts and T-nuts, only to realize that the allen head bolts I had gotten were not long enough, so I wound up using #12 2 1/2" wood screws that I had already. While not ideal, I'm sure that the driver is still plenty well fastened. I can always add them later, (when I finish the box).

Anyway, I've posted a few pictures. Thanks again to all who helped me. It is very much appreciated. I will let you all know how it sounds soon.

Regards, MP-
 

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Discussion Starter · #8 ·
Update:

I was able to fire it up today. It is being driven by an EP2500 bridged. I set it up in my system that I use exclusively for music first, simply because it is far more easily accessible. The system is made up of 2 Polk Audio RTi 10's bi-amped using an HK 5800, with a Sherwood Newcastle AVP-9080 pre-pro.

My initial impressions were:

The sub is able to keep up effortlessly, even at ridiculously loud listening levels (no surprise there). It also seems to be fairly musical. The sub is also extremely accurate, and does not sound boomy at all (very tight bass). While it seems to excel in all areas, there were two facets that really seemed to impress me. The first was how incredibly well (and realistically) it reproduced bass (kick?) drum beats on rock tracks, and the second was the accuracy in which it played all different types of tracks at any listening level. I didn't have much time for auditioning and tinkering, to better integrate it into the system, but I hope that I will soon.

As for HT, I am very interested in seeing how well it will perform (as that is the primary use for which it was built). I hope to audition it in the HT soon. However, things have been incredibly busy as of late with a new job, several projects to do around the house, and a 2 1/2 year old keeping her parents always on the go. At this point, I'm just happy to be able to get some initial listening impressions.

Unfortunately, at this point, I have neither the equipment or knowledge to do much further testing, (response curves, SPL tests, etc.) I can say that this sub/amp combination (even in this relatively small sealed box) will not let you down, especially if you watch movies or listen to music at fairly high sound levels in larger than normal listening/viewing areas.

I also wanted to update the box specifics I posted earlier. The internal measurements of the enclosure are actually 21 3/4" x 21 3/4" x 21 1/4" (HWD). After subtracting out roughly 1 ft^3 for bracing and driver volume, the actual net volume of the box is 5.82 - 1 ~ 4.82 ft^3. It is also stuffed with 80 oz. of polyfill (16 oz./cubic foot) per Kevin Haskins' recommendation.

While not incredibly informative, I hope this post will at least give you some idea of how well this sub can perform in a small, sealed enclosure.

Regards, MP-
 

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Thanks for the kind words and the sub looks great!

I'm very glad to hear that it sounds good. Some people think we're all crazy for wanting such a big and powerful subs, but what they fail to understand (and you noticed) is that a sub this big can do a lot of things well - you don't have to push it as hard as you would a 10" or 12" sub.

Can't wait to get mine done...especially after hearing your impressions!
 

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Awesome build. I'm considering the (almost) exact same setup.

I've already got an EP2500 (best performance/price ratio in the amp area I think, no?), and a Shiva-X in a 120L ported box. Admittedly, the box isn't perfectly tuned (<22Hz at full volume, the port becomes noisy...).

Do you have any more pictures for us? :)
 
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Looks like an awesome build. I am very new to DIY subs/rather any speaker. I want to build a sub for my 7000 ft^3 area and I was suggested the Maelstrom with the EP2500. I am all pumped up on building this sub, but I have a few questions to the experts who have built it. Please excuse me if my questions sounds silly.
Do you have a shopping list that you used and where did you purchase the parts from (other than the driver and amp) ?
Do you have pictures of the wiring that was done inside to connect the driver to the outside plates ?
Would you have a circuit diagram or detailed instructions on wiring ?
Is it possible to integrate the amp into the sub instead of placing it on the top ? I was thinking of the plate amp that diycable has (500W), obvious this is not the best choice for this sub.
Do I need an equalizer if I am feeding the sub from a reciever ?
I see that the driver is exposed to the outside, is there a need to cover the driver with a potective speaker cloth or mesh ?
I appreciate any help you guys can provide.
 
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