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post #1 of 32 Old 03-25-2013, 09:08 PM - Thread Starter
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So I've decided to build a subwoofer using the 15 inch Dayton Ultimax. I've decided to go a box that is 20.66" width, 21" height, 20" Depth. I think I might bump the height up to 23" so I can account for bracing. This would be 4 cubic feet. Is it preferable to use a 4 CU box or a 3 CU Box since I see the flatpacks sold for the Ultimax are 3 CU? So maybe I should just make a box that size? Also, how much polyfill should I use? This is a sealed enclosure. The bracing I plan to go with is the dowel method Bill has in his diagrams.

Finally, I'm wondering what subwoofer a 15 inch dayton ultimax build would compare to that's a retail subwoofer sold? I want to see how much I'm saving going with DIY to see if it's worth it for me. The wood is free which helps and I should be able to get access to wood working equipment at school.

I'm very close I feel to being ready to attempt this build so quite excited.
Here is a parts list I have so far.

Primer
http://www.homedepot.com/p/BEHR-Premium-Plus-1-Qt-Stain-Blocking-Interior-Primer-Sealer-07504/100117887?N=bt0tZ1z11cv2#.UVEZiRysh8E
$10
Polyurethane
http://www.homedepot.com/p/Minwax-1-qt-Gloss-Fast-Drying-Polyurethane-63000/100136801?N=25ecodZbbbpZ1z10lit#.UVEYmxysh8E
$11
Haven't Picked out paint.

Subwoofer
http://www.parts-express.com/pe/showdetl.cfm?partnumber=295-514
$170

Spikes
http://www.parts-express.com/pe/showdetl.cfm?partnumber=240-718 (Might substitute with something cheaper at first)
$30

Polyfill
http://www.parts-express.com/pe/showdetl.cfm?partnumber=260-317
$30

Speaker Grill Cloth
http://www.parts-express.com/pe/showdetl.cfm?partnumber=260-335
$14

Terminal (May just not use the cup though)
http://www.parts-express.com/pe/showdetl.cfm?partnumber=260-309
$5

External Amplifier
$350

So coming in at around $650. I guess you could say it's around $450 since I could power 2 subs with the external amplifier. Just wondering how much added benefit I'm getting from going DIY and whether or not I'd be better off just buying a 600 dollar subwoofer. What retail subwoofer would this build be comparable too so I can decide myself whether it's worth the trouble vs just purchasing a subwoofer. I can envision the end product though and I really like the thought of it.

Anyhelp finishing this project would be great!
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post #2 of 32 Old 03-26-2013, 07:30 AM
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What amp are you going with? 4 ft3 is more ideal, but dont worry so much about being exact with the volume, one of the benefits of a sealed design. Skip that polyfil, go down to walmart/target and buy 2-4 poly filled pillows for $2 ea.

As far as a commercial comparison, something like a HSU ULS15 would be a good one.
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post #3 of 32 Old 03-26-2013, 08:16 AM - Thread Starter
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Since I already own a Crown XLS 1500, I might buy another one of those. I'm open to any amp suggestions though as I know this sub can handle up to 800 RMS. I don't want an amplifier that I can only power 1 sub off of. I figured I could wire it in such a way that I could split the 1550 bridged mono mode between 2 subs which almost gets their RMS level of 800 but I knokw I could do a higher end Crown XLS or other amps.

Good call on the pillows didn't even think of that. I wasn't too worried about the volume being exact after playing with WinISD. If it compares with the HSU ULS15, then I'll be happy with the subwoofer. Especially since it will be exactly how I want it if I build it.

My last questions(that I can think of ) have to do with bracing and mounting the subwoofer.

Bracing I was going to use dowels. From what I read here it's easy and effective. Just curious as to how I slip them in though and glue them into place.

Can I glue them into place before hand and then assemble the box?

Or

do I need to slip them in, and cut those 1/16th indents so they just slide and lock in. If so how do I glue both sides so it stays?

Also for the subwoofer, how do I make the cut so I can mount it flush? And is flush mounting the subwoofer necessary? I've had some thoughts of just leaving it out and proud. Save some time, and it will be covered with a grill at all times. Besides, I think I may even like it mounted that way.

Ugh, so close til I can start actually building!
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post #4 of 32 Old 03-26-2013, 08:38 AM
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My build is still underway for my UM15, but I just went with 21" sides all around (cube) to keep the design and cuts a little simpler. It's just shy of 4 ft^3.

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post #5 of 32 Old 03-26-2013, 10:49 AM
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Quote:
Originally Posted by tential View Post

Since I already own a Crown XLS 1500, I might buy another one of those. I'm open to any amp suggestions though as I know this sub can handle up to 800 RMS. I don't want an amplifier that I can only power 1 sub off of. I figured I could wire it in such a way that I could split the 1550 bridged mono mode between 2 subs which almost gets their RMS level of 800 but I knokw I could do a higher end Crown XLS or other amps.

It's always best to buy double the amp power needed. This is especially true for class D designs that only list burst-power; unlike the old-school big-iron H amps that could probably be trusted to meet their RMS ratings indefinitely (or at least for the duration of a 6 minute song).

The amp will thank you when only having to run at -3 or -6db, as opposed to very-near clipping.
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post #6 of 32 Old 03-26-2013, 12:58 PM
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4 cu ft looks about ideal for this driver, although 3 cu ft ain't bad either. Don't sweat a little box volume.

The secret to dowel bracing is expanding glue. You cut the dowels before box assembly, but install them after. Sand the ends judiciously to get a good fit. Urethane glue (Gorilla glue) and PL Premium construction adhesive, among others, expand as they dry. You get a stiff foam where it squeezes out, and a good bond where it doesn't.
- Cut the dowels a little short, like 1/2 mm
- bevel one end a little on one side so it it fits between the panels. The bevel also forms a pocket to trap glue
- apply a bead of glue where you want the dowels
- stick one end in the glue pile
- swing the other end into place, trapping the glue under the bevel as you swing to perpendicular
- let dry completely

This type of brace works by connecting two sides, so they can't move out of phase. Since that's the only mode the speaker can drive, no resonance can occur. Think in terms of a balloon; add air and sides move away from each other - 180 degrees out of phase. Here's a god pattern.
http://techtalk.parts-express.com/showthread.php?236464-Subwoofer-Build-Questions&p=1898115#post1898115

Flush mounting a sub is optional, as are grills. One thing to consider is a double-thickness baffle. This side has a big hole in it, so extra support won't hurt.

For finish, consider truck bed liner. No priming, no sanding, looks really good when dry. There's also roll-on material with similar properties.

Get building, and...

HAve fun,
Frank
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post #7 of 32 Old 03-26-2013, 01:13 PM - Thread Starter
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Quote:
Originally Posted by fbov View Post

4 cu ft looks about ideal for this driver, although 3 cu ft ain't bad either. Don't sweat a little box volume.

The secret to dowel bracing is expanding glue. You cut the dowels before box assembly, but install them after. Sand the ends judiciously to get a good fit. Urethane glue (Gorilla glue) and PL Premium construction adhesive, among others, expand as they dry. You get a stiff foam where it squeezes out, and a good bond where it doesn't.
- Cut the dowels a little short, like 1/2 mm
- bevel one end a little on one side so it it fits between the panels. The bevel also forms a pocket to trap glue
- apply a bead of glue where you want the dowels
- stick one end in the glue pile
- swing the other end into place, trapping the glue under the bevel as you swing to perpendicular
- let dry completely

This type of brace works by connecting two sides, so they can't move out of phase. Since that's the only mode the speaker can drive, no resonance can occur. Think in terms of a balloon; add air and sides move away from each other - 180 degrees out of phase. Here's a god pattern.
http://techtalk.parts-express.com/showthread.php?236464-Subwoofer-Build-Questions&p=1898115#post1898115

Flush mounting a sub is optional, as are grills. One thing to consider is a double-thickness baffle. This side has a big hole in it, so extra support won't hurt.

For finish, consider truck bed liner. No priming, no sanding, looks really good when dry. There's also roll-on material with similar properties.

Get building, and...

HAve fun,
Frank
Thanks a lot, especially with the dowels stuff. After reading that I feel really confident to start this build. Hoping this turns out as good as people say it should. I think going to try the glossy finish. I don't have much to do other than school so if there is a time to sit and paint and sand its now. Besides, I love glossy finish. I plan on building a full setup with reflective white glossy speaker enclosures, if this works so that I can possibly use them later when I have money. Free wood makes this a lot less stressful.

Today though, going to put together the rest of the measurements I need to at least build the box.

Last thing I'm curious too actually is how do I cut the baffle hole to the right size. Should I assume it's exactly 15 inches or do I trace it first and cut from that or something?
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post #8 of 32 Old 03-26-2013, 01:19 PM - Thread Starter
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Originally Posted by BassThatHz View Post

It's always best to buy double the amp power needed. This is especially true for class D designs that only list burst-power; unlike the old-school big-iron H amps that could probably be trusted to meet their RMS ratings indefinitely (or at least for the duration of a 6 minute song).

The amp will thank you when only having to run at -3 or -6db, as opposed to very-near clipping.
Uhh sorry for double post I can't edit on my phone right now. Ya, km going to use the current crown xls to see how it manages. If I wire in parallel I'd get a 2ohm load with 2 subs so ill test that too before I potentially buy a larger amp that I don't use.
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post #9 of 32 Old 03-26-2013, 01:41 PM
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Originally Posted by tential View Post


Last thing I'm curious too actually is how do I cut the baffle hole to the right size. Should I assume it's exactly 15 inches or do I trace it first and cut from that or something?

You can use the dimensions from the PE link.

MOUNTING INFORMATION
Overall Outside Diameter 15.28"
Baffle Cutout Diameter 13.78"

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post #10 of 32 Old 03-26-2013, 02:04 PM - Thread Starter
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You can use the dimensions from the PE link.

MOUNTING INFORMATION
Overall Outside Diameter 15.28"
Baffle Cutout Diameter 13.78"
Oh wow thanks!
Now to find a woodworking place on campus (why it's so hard to find a public one when each college has one) or use a friends id(dumb I have to sneak into facilities I pay for).
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post #11 of 32 Old 04-07-2013, 03:36 PM - Thread Starter
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Ok just an update. I got clamps finally, apparently we can't check out the larger ones so I ended up buying some for 15 bucks. Glued together all the sides except the top and the front baffle.

I know how to put the Dowels in, but how many/what diagram to use? I saw the one posted in here but it's only showing a top down view. I assume I need to brace all 3 sides.

Also, as for filling the box with polyfill, how do I go about this? I assume I don't want it going everywhere and touching the actual subwoofer right?

Finally, as or finishinng, I'm trying to achieve a gloss red finish. I have the primer, and paint, and sand paper, but can I paint using a brush? I see everywhere that I should use a spray, but I don't have money to get all that haha. I was going to Prime, sand, prime, sand, prime, sand, red paint, sand, red paint, sand, red paint, then sand with 400, 600, 800, 1000. Just curious as to the actual details since I'm a complete DIY noob. I've built computers but never actually assembled anything before.

Edit: I was going to go with 1/2 inch dowels since they're really cheap at home Depot. 2 inch ones were like 8 dollars Compared to 1/2 inch for 2 dollars.
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post #12 of 32 Old 04-07-2013, 05:17 PM - Thread Starter
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Also, for cutting the hole for the driver drop in, do I just do that free hand?
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post #13 of 32 Old 04-07-2013, 05:23 PM
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There is a great thread with many of your questions answered in it, titled New to DIY? FAQ's in here.

I've read it 3-4 times and find tidbits every time I read it again.

Most people use a router and jig for cutting circles, though not needed, a jigsaw can do the job as well.
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post #14 of 32 Old 04-07-2013, 07:12 PM - Thread Starter
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I didn't see a dowel bracing diagram which is what I was looking for. I just saw some theory on dowel bracing but there are more than just bracing 2 sides together.
Also I see things on finish but not on gloss finish and I want to know about using a paint brush since everywhere I read talks about spray cans.
None of these were answered in there.
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post #15 of 32 Old 04-07-2013, 07:12 PM - Thread Starter
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I didn't see a dowel bracing diagram which is what I was looking for. I just saw some theory on dowel bracing but there are more than just bracing 2 sides together.
Also I see things on finish but not on gloss finish and I want to know about using a paint brush since everywhere I read talks about spray cans.
None of these were answered in there.
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post #16 of 32 Old 04-07-2013, 07:24 PM
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I didn't see a dowel bracing diagram which is what I was looking for..
Like this one?


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post #17 of 32 Old 04-07-2013, 07:53 PM - Thread Starter
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Like this one?


Yes. I wasn't sure how much to buy. I was going to buy the 1/2 inch ones because they're 46 inchces long and are only 2 dollars a piece. Will those work with that diagram?

Edit: Also, I tried to model cone excursion on winisd pro and I'm getting that I'll hit xmax, at 800 W input power, at 33 Hz. Does that sound right? This is in a 4 ft cubic sealed box. I followe to tutorial for inputting the numbers exactly and winisdpro accepted them.
Edit2: I also just realized the wood is .5 instead of .75 thick (I was skeptical the whole time because I was getting some overhang. This means I'll need more bracing right?
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post #18 of 32 Old 04-08-2013, 12:55 PM
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The plywood's 1/2"? And the dowels are 1/2"? Bill's always said you can build it light if you brace it right, but I think you're a little light using 1/2" dowel braces - 1" minimum, better 1.25 or 1.5". They don't work if they bend... 1/2" bends too easily as doens 3/4".

Fill goes everywhere, BUT right next to the driver. Give it a couple inches of breathing space all around. Fill also can be stuffed loose (0.5 lb/cu ft) or dense (4 lb/cu ft) affecting Q (denser is lower), which allows you to tune your box, if desired. At minimum, 2" on the walls is never bad, but some say a sub works fine empty...

HAve fun,
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post #19 of 32 Old 04-08-2013, 01:11 PM - Thread Starter
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Ya, I didn't pick the wood my friends get it free from class and they did the curs for me. I'll look around then for the cheapest option above an inch and buy that for the 12 braces I need along with 2 pillows with polyfill from Walmart.

Last thing I was wondering was how do u attach subwoofer spikes to this thing. Purely for aesthetic purposes, whether it helps or not is a bonus but I just wanted to get feet. Do I need to glue more wood to the box so I don't drill into it or is it ok to drill right into the box and put the feet into it. I couldn't find a thread about it, only threads about whether it helps or not.
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post #20 of 32 Old 04-08-2013, 01:43 PM
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The plywood's 1/2"? And the dowels are 1/2"? Bill's always said you can build it light if you brace it right, but I think you're a little light using 1/2" dowel braces - 1" minimum, better 1.25 or 1.5". They don't work if they bend... 1/2" bends too easily as doens 3/4".
You could get by with 1/2" dowels, but you certainly don't have to. But as for bending, they won't. The forces that are placed on the dowels try to stretch and compress them, not bend them. Unless you want to: the advantage to 1/2 inch is that you can drill sockets on the opposing panels to seat the dowels and bend them just enough to snap them into place.

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post #21 of 32 Old 04-08-2013, 02:14 PM - Thread Starter
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You could get by with 1/2" dowels, but you certainly don't have to. But as for bending, they won't. The forces that are placed on the dowels try to stretch and compress them, not bend them. Unless you want to: the advantage to 1/2 inch is that you can drill sockets on the opposing panels to seat the dowels and bend them just enough to snap them into place.

The thing is, the 1/2 inch dowels are more cost effective.
1/2 inch dowel is 48 inches l;ong is $1.54.
1 inch dowel is 48 inches long is $3.58.

No other sizes make much sense. I'm just not sure how much bracing to use given the size of the dowel.
Going off the diagram, and your other posts about bracing, I was going to use the 1 inch dowel right in the center of the box going up and down. Then 4 in a square formation on each side (13 braces total).

I'd use the 1/2 inch dowels if I can get away with it, but I'm not sure how much would be adequate.

Pretty much wondering how much bracing I need to use given a 1/2 dowel and a 1 inch dowel so I maximize my money and don't waste it on unnecessary braces.
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post #22 of 32 Old 04-08-2013, 03:05 PM
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I'm just not sure how much bracing to use given the size of the dowel.
The size of the dowel doesn't matter, a 1/2 inch will work just as well as a 2 inch. What matters is the distance between them. With a 1/2" plywood cab a 6 inch brace matrix spacing would be inert.

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post #23 of 32 Old 04-08-2013, 04:29 PM - Thread Starter
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The size of the dowel doesn't matter, a 1/2 inch will work just as well as a 2 inch. What matters is the distance between them. With a 1/2" plywood cab a 6 inch brace matrix spacing would be inert.

I wish I knew what that meant. I assume you mean that every 6 inches there is a brace for each side?
Google wasn't much help either and my own guesses didn't make any sense.

How many braces connect each side? In your diagram I see 4 connecting each side. My cabinet is 22x20x20 inches. I'm guessing it's between 4 and 6?
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post #24 of 32 Old 04-08-2013, 07:16 PM
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I wish I knew what that meant. I assume you mean that every 6 inches there is a brace for each side?
This would be the end on view of braces connecting 24 x 24 inch panels:



If you only used the red brace with 1/2" ply panels the stiffness would be the same as unbraced 1" panels. Using the blue braces the stiffness is the equivalent of unbraced 2" thick panels.

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post #25 of 32 Old 04-09-2013, 10:21 AM - Thread Starter
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Quote:
Originally Posted by Bill Fitzmaurice View Post

This would be the end on view of braces connecting 24 x 24 inch panels:



If you only used the red brace with 1/2" ply panels the stiffness would be the same as unbraced 1" panels. Using the blue braces the stiffness is the equivalent of unbraced 2" thick panels.

So I should use 9 braces to connect each side for a total of 27 braces? (26 I I guess since I couldn't use a red brace on the side where the subwoofer is).

Also, should I go over the edges with a woodglue/water solution? Or something else? I could take some pictures just to show, maybe it's my paranoia but now that box painting is comign close and close I want to make sure I didn't mess up anything lol.
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post #26 of 32 Old 04-09-2013, 10:39 AM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

You could get by with 1/2" dowels, but you certainly don't have to. But as for bending, they won't. The forces that are placed on the dowels try to stretch and compress them, not bend them. ....

Oddly enough, Bill, when I compress a thin dowel along its axis, it bends very nicely! All I have to do is push hard enough... no one makes 1/2" canes.

Clearly the amplitudes here are small, but the likelihood of enough compression force on the dowel to cause lateral center displacement is quite high. Remember this driver at rated Xmax swings internal volume by 15.5L (out of 112L). The resulting vacuum (assuming constant temp) puts 860 lb. of compressive force on each side which will easily cause 1/2" plywood to deform, transferring the force to the braces.

Budget a couple bucks extra per dowel, or plan on connecting all your braces in the center to get a stiff box. When you sit on the box, you want it to deform like a rock, not a drum head.

Have fun,
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post #27 of 32 Old 04-09-2013, 11:21 AM
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Oddly enough, Bill, when I compress a thin dowel along its axis, it bends very nicely! All I have to do is push hard enough... no one makes 1/2" canes.

Clearly the amplitudes here are small, but the likelihood of enough compression force on the dowel to cause lateral center displacement is quite high.
I can bend a 1/2" dowel easily enough too but only because I'm not applying force on a perfect axial vector. IME 1/2" dowels spaced 6 inches don't flex, but if one wants to tie them together as suggested it wouldn't hurt.

Bill Fitzmaurice Loudspeaker Design

The Laws of Physics aren't swayed by opinion.
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post #28 of 32 Old 04-09-2013, 12:35 PM
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I just finished my 15" sub, I used 3/4 MDF with a double thick baffle. I also added 4 -1" oak dowels in each little section. I used the bash 300W amp that PE had on their deal of the day ($99.00) that I couldnt pass up, mounted it on the outside. I think its plenty, I have only turned the gain up to half and it shakes the whole house - and this is sitting on a cement floor in the lower level. I used PE's stick-on black ash vinyl to finish it, looks ok but the edges were a pain.

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post #29 of 32 Old 04-09-2013, 01:28 PM - Thread Starter
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So how many 1 inch dowels should I use if I use an equal amount to brace each side. I was thinking 4 per side for a total of 12?
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post #30 of 32 Old 04-09-2013, 01:40 PM
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If you are doing like the picture a few posts back with dowels only - that sounds right. Dowels dont really add much weight or take up much space. i was thumping the sides after putting in the cross braces, you can hear if more bracing will help. This woofer really puts out some air and if you are only using 1/2 wood I dont think 12 is overkill.
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