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I'm noticing the main DIY Sub section seems to be getting more traffic then where my Maelstrom-X 21"build thread is in the Exodus section. I just want to bounce some ideas/thoughts off the more experienced builders before I cap this box (probably a bit late for some things, but it's good to know regardless).

I've built many car audio boxes, but that was back in the late 80's early 90's. Subs have come a long way since then! My current box is a dual 10" folded horn based on the Decware Wicked One design...I built this about 10 years ago now! http://lonelyraven.zenfolio.com/img/v2/p573447152-4.jpg

So I'm figuring it's time for me to upgrade since the LJ Audio 10" drop like a rock below 30Hz, and I'm 95% Home Theater and 5% background music lately. So I let Kevin of DIYCable.com talk me into a 21" Maelstrom-X in a sealed box. He recommended a 12ft^3 box, but I was having fun with numbers and caught some plywood on sale, so I decided to go a bit bigger. I know I'm beyond the point of diminishing returns, but it's a fun build and should show results regardless.

The box (airspace) is 41" X 37" X 23" (those who paid attention in class will recognize these are primes). I made all the bracing asymmetrical, and they are also on primes. All the bracing is installed in the box at prime number spacing...(11" 13" 17" 19" 23" etc) making sure brace to brace spacing isn't evenly divisible, and I've added a band of bracing around the middle of the side panels which breaks the height into 11" panels. So my questions:

Does this look like enough bracing considering the size of the box?





I grabbed some "deep pockets" fiberfill pillows for the airspace, but I have some rockwool acoustic blankets I could put in there...would the rockwool help damp 1/4 or 1/2 wave internal resonance??





I saw Ricci's sealed test enclosures, and I had already planned on doing a removable (3 layers of 3/4 ply) baffle similar to his. But his boxes made me feel like mine was underbuilt. I just wanted to get more sets of eyes looking at the build before I sealed it up for good.

I'm open to suggestions!
 

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Shoot...Looks good to me. BTW did you see how I did the baffle on the sealed boxes? Use 2x2 for the anchor for the baffle to mount to and overlap the last baffle layer while allowing the first 2 to drop inside the cab to meet the 2x2. Weather strip all of that. You may want to use threaded inserts instead of T-nuts if you do this. The T-nuts have given me horrible problems with spinning and cross threading on occasion.
 

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Discussion Starter #3
Shoot...Looks good to me. BTW did you see how I did the baffle on the sealed boxes? Use 2x2 for the anchor for the baffle to mount to and overlap the last baffle layer while allowing the first 2 to drop inside the cab to meet the 2x2. Weather strip all of that. You may want to use threaded inserts instead of T-nuts if you do this. The T-nuts have given me horrible problems with spinning and cross threading on occasion.
Thanks Ricci. I'd already started gluing and pinning the anchor strip when Callas suggested I triple or even quadruple baffle for the Mael-X 21". So short of starting to tear things apart, I'm kinda stuck with what I have now. I might go with inserts over T-nuts though. In fact, I already have to return the stainless screws I bought and buy some longer ones due to the increase in baffle thickness.

Food for thought, thanks.

Hey, what do you think about using the rockwool inside the box? I was thinking a 3" layer (it's similar to OC703 but a blanket rather then a panel) between a row of pillows. Just for damping, as I'm already over the airspace I need for a sealed box.
 

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Discussion Starter #5
The Rockwool should be fine. Keep us updated with pics. GL.
My build thread has tons. Photography is one of my many passions...though I've been pretty lazy about it lately.

Out of the blue, I got an offer on my folded horn with JL Audio speakers last night. I think I'm going to go ahead and sell them...though I'm practically giving them away at $450 with the enclosure.

With that money, or about $300 of it, I'm looking at getting some EQ in my system. Any recommendations? Kevin pushes the SMS-1, but I thought it had problems below 20Hz or something. I'm looking for something with lots of options so I'll keep it for years, I'm hoping $300 or there abouts is enough for a good bass EQ
 

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I vote for a Behringer DCX2496. About $250 last I checked. It is a swiss army knife of audio. More advanced but way more flexible. You cna only EQ down to about 15hz getting creative, but it just does so much. Do you have an SPL meter and REW? If not maybe try to get that going so you can evaluate what your sub and room is doing, which will help you implement the EQ.
 

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I vote for a Behringer DCX2496. About $250 last I checked. It is a swiss army knife of audio. More advanced but way more flexible. You cna only EQ down to about 15hz getting creative, but it just does so much. Do you have an SPL meter and REW? If not maybe try to get that going so you can evaluate what your sub and room is doing, which will help you implement the EQ.
I'm sorry, I should have clarified; I do in fact have the Ber mic and phantom power, and I've used REW before, but it's been over a year...so I have to relearn it.

I did wind up selling my old subs, so I have cash in my pocket that can either go towards bills, or EQ. :spend:
 

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Discussion Starter #8
Ricci,

What would the DCX2496 do for me that the $150 BFD doesn't do?

The box is built but not painted, I've been giving it some light duty work with Star Trek and lots of music. I want to dial it in better for the room and be done with it for now.
 

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DCX is capable of crossover slopes both high and lowpass of up to 48db octave at almost any frequency. It can EQ using parametric filters or do shelving or BP type filters. It can adjust the in and output gain of each channel, it can do dynamic EQ that adjusts things based on the volume of the signal. It can indepedantly adjust the distance (phase) of each channel. It can be controlled remotely by computer. It can do all of these adjustments independently for each channel. 3 in and 6 out.

Probably more power than you need, but I always favor having too much.

Down the road if you add another sub or whatever it can independently tweak out each one.
 

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DCX is capable of crossover slopes both high and lowpass of up to 48db octave at almost any frequency. It can EQ using parametric filters or do shelving or BP type filters. It can adjust the in and output gain of each channel, it can do dynamic EQ that adjusts things based on the volume of the signal. It can indepedantly adjust the distance (phase) of each channel. It can be controlled remotely by computer. It can do all of these adjustments independently for each channel. 3 in and 6 out.

Probably more power than you need, but I always favor having too much.

Down the road if you add another sub or whatever it can independently tweak out each one.
Wow, thanks for that!

It does sound a bit much for what I need now. I tend to overbuy so I'm not left wanting (hence the 21"), but the $150 version should suit me. Thanks for the recommendation!
 
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