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Discussion Starter #41
who needs to drink his cofee now? ;)
The sad thing is, I've read Kevin's papers on the 21 probably a half-dozen times now.

I think I just read so much (when you include forums and books) that I get data-overload and forget more then I remember.

That said, I happen to be having my second cup right now at 1PM. :blink:
 

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It's not surprising you get data overload when you have a cold.
My head feels like it's stuffed with cotton wool when I have one.

That box is going to be impressive when it's finished. I usually cheat when making boxes by cutting the two sides exact and then using a trim router bit to match in the rest.
 

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Discussion Starter #43
It's not surprising you get data overload when you have a cold.
My head feels like it's stuffed with cotton wool when I have one.

That box is going to be impressive when it's finished. I usually cheat when making boxes by cutting the two sides exact and then using a trim router bit to match in the rest.
I thought about that as well, and I often do use a trim router to clean everything up, but with my table saw so finely tuned, I'm literally within 1/64th on all my cuts (assuming I head is in the game). The panels were slightly bowed, so the top and the bottom wont line up perfectly. To compensate, I tighten the clamps half way, then tap the panels into place using a rubber mallet (friction from clamps holds them where I tap them), then I full on clamp to keep the panels there. I was going to build this without nails or screws, but the warped panels made me use fine brads shot from my pneumatic nailer to help assure the tension of the warped panels glued straight wouldn't pop then loose under pressure (read bass).

I also used the warped panels to my advantage by putting the curve on the inside of the box to add tension between the bracing and (Warped) side panels. All this, plus quality adhesive, brads, silicone sealant (even on the bracing) should add up to a solid cab.
 

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Discussion Starter #44
OK, it's 1:30AM and I need to be up for work in 4 hours. So I'll try and make this quick.

I was PM'd and asked to take some photos AFTER I've glued the bracing in...it's not really any different then the dry fit, but I figured I'd take a few more photos...while I was staring at the box, I got a wild hair to divide the panels up a bit more, so I wedged a wooden waist line all the way around the box, right in the middle. I also added a rail around what will be the baffle of the box because I want to make the baffle removable in case the driver ever needs service. I'll be adding a couple more bracing pieces once I get the top of the box glued in.




I drove over to Walmart to pick up some Deep Pockets pillows. I'm not sure how heavy these are...I figure 2 pounds maybe? Well, I got six tonight (on sale for $2.50 this week), and I'll probably pick up 3-4 more once I get the top glued on.





I figured I'd load them in from the back going forward, so I could add the last few pillows after the top is on. They sure do say fiberfill on them! (I also broke the law by taking off all those do not remove under penalty of law tags...I'm such a rebel!)





Then I silicone adheasived, clamped, pinned with brads, clamped some more, and piled up the weight on top. There is an 80lb battery backup, and two 40lb buckets of kitty litter on there. I was tempted to throw my garage mini-fridge up there, but I'd be surprised if it was as heavy at the battery backup that was up there already.




I used 2X4 to help distribute the pressure of the parallel clamps across the top while I brad nailed the panels together. I'd tighten the clamps, nail like mad, move the clamps 6", then nail like mad etc.





I don't have photos of it, but I glued up two 3/4" panels for the baffle. I'll be adding a third panel tomorrow once I can take the clamps off the top of the box. I'm going to try and size up the baffle so it fits into and over the opening in the box like a cork. It's going to be pretty dern tight, plus I'll have some gasket material, and stainless industrial screws pulling it all together. OH! And I still need to decide where I'm going to put the binding posts!
 

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Love your work.

This is going to be one insane sub once finished. :devil:
 

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Discussion Starter #48
Thanks guys, that means a lot. A build this size is new to me as I'm used to smaller, more intricate builds. I still have things I feel like I'm fumbling through...so lets hope I get it all figured out in the end.
 

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As opposed to using screws, I'd imagine the mounting holes on the frame of the driver would be large enough to use 1/4" bolts, no? If not, a quick reaming with a 1/4" drill bit should do the trick. The advantage to bolts would be that you could use t nuts and allow for easier removal/re-attachment of the driver as well as less chance to strip the threading in the wood.
 

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Discussion Starter #52
As opposed to using screws, I'd imagine the mounting holes on the frame of the driver would be large enough to use 1/4" bolts, no? If not, a quick reaming with a 1/4" drill bit should do the trick. The advantage to bolts would be that you could use t nuts and allow for easier removal/re-attachment of the driver as well as less chance to strip the threading in the wood.
I was going to use 1/4" Allen Head bolts actually, with T-nuts glued into the backside. I was looking at 1/4" bolts, and I'm not sure the heads would make it past the lip on the mounting flange.

Either way, I'm going to make sure it's secure!! Having it come loose and break itself is a scary thought!
 

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Discussion Starter #55 (Edited)
Tonights update!

So early on I realized my Jasper circle jig just wasn't going to work for the 21" driver. I kinda giggled at that when I was looking at the jig and realized it ended just over 18"! So I cobbled one together with scraps on hand.







Many years ago I promised myself that when I get a house, I'm going to have a nice garage workshop with lots of tools. Tools are expensive...but when I bought this house last year, I set aside a $1500 budget for tools. $1500 didn't last long, but I made fine choices. So you'll notice a lot of Bosch tools in my photos and in the background. One of my favorite expenditures, was this awesome spiral router bit. 3 blades, and sharp enough to cut you if you look at it wrong! (note, thats red dust from bloodwood on there, not rust!)




Ready to roll with the Bosch plunge router and my wicked spiral bit (and home made circle jig!). You can see the 3" hole in the far corner of the baffle that will house the speaker jacks. Mind you, this is only two layers of the baffle, I'll cut the 3rd one after it's glued to this one. I did this for two reasons. First these two panels line up flush with the outer face of the box, so I wanted to line up the 3rd and final panel perfectly with the edges of the box. And Second, it's not very safe to router a 19.5" hole 2.25" deep!




I think I took about 6-7 passes lowering the bit each time. That bit dug through this like a warm spoon into ice cream. Slow, and smooth!





Then I had to test fit the driver of course! The hole is *exactly* 19.5" and the driver still has about 1/16" play. I may do the 3rd layer of the baffle at 19.44" to snug it up a hair. Either way, I have plenty of mounting surface for the 1/4" screws I got. (Note, I put the drill in the photo to help show scale...that drill is a HUGE 36v monster that weighs like 9lbs with the big battery)





And the two layer baffle press fit into the box. I had this thing dern near air tight by sanding the baffle to fit the slot, only to find out the top was sagging a little because of the weights I still had on it. :rant: My bad. The 3rd baffle and thin insulation tape I got should more then make up for the slim gap at the top. Otherwise, this thing is pretty snug and press fits in.







And before I go to bed, I drew out the lines showing how best to line up the 3rd layer to the baffle, and glued it up! Hopefully it didn't slip at all while gluing it down. Large panels like this tend to "float" on the glue till you get it clamped in two or more places. I think I got it pretty close!



While I was contemplating my next and hopefully final steps (besides painting, which will come at a much later date), I added more screws and nails to the layers of baffle, added a couple extra pieces of bracing around where the baffle meets the inside of the box, and siliconed the bracing and cleats the baffle will mount on to further insure it will remain leak free.


On a sad note, I got hit with a double whammy today. First (and least) the guys who were going to buy my old subs and box bailed on me...I was kinda counting on that money. And, my boss informed me today that I have a meeting with HR tomorrow...it looks like my company is letting more people go this week, possibly including me. :doh:
 

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On a sad note, I got hit with a double whammy today. First (and least) the guys who were going to buy my old subs and box bailed on me...I was kinda counting on that money. And, my boss informed me today that I have a meeting with HR tomorrow...it looks like my company is letting more people go this week, possibly including me. :doh:
awesome pic! wow. just WOW. I hope he makes a rubber gasket down the road to cover the mounting flange though.

sorry to hear that news, hope all works out well!
 

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Discussion Starter #57 (Edited)
Alright, another late night. It's 1:15AM as I'm writing this, and I have to be up at 5:30AM again. Coffee will be my friend.

On a positive note, the guys who were wanting my old JL Audio subs showed up with cash in hand, and I didn't get laid off from my job! Ahhh, the ebb and flow of life....

So tonights update. I'm going to try and make this quick as I'm just about asleep on my feets!

With the third layer added to my baffle, I start routing the counter-sink for the woofer, and the cutout.





Done and sealed with insulation. This stuff was thicker then I wanted, but I couldn't find any of the 1/16" closed cell foam tape I used to use back in the day. This is a better quality material, just too thick (as you'll see when I show the baffle installed).





I guess I forgot to take any photos of me physically installing the woofer. Hefting it around, plus being really cautious no tools slip into and stab the surround, I can see how I was ignoring the camera. Long story short, flange head 1/4" 20 X 2" (and 2.5" since I couldn't find enough 2") bolts, and 1/4" deep thread T-nuts glued in with Gorilla Glue, then torqued with a torque wrench to 2.5lb ft. I don't have an inch pounds torque wrench, but this felt right...and this being a cast frame, I wanted to make sure I tighten them equally *AND* like lug nuts. Meaning, you tighten them Top-Bottom-Left-Right-Lower left- Upper right-Upper left-Lower right. Not around the frame which would build tension in the metal and possibly crack it.





Tools to take care of the wiring.





Whilst the soldering iron was warming up, I decided to add a layer of Rockwool acoustic insulation, and the last row of Deep Pockets Pillows.










That took about 7-10 minutes, so the soldering iron was warm, and I put this together really quickly and easily. Either this is a good example of series wiring, or everyone on the intarwebs will laugh at me for forgetting how to wire in series. :D





And the input "cup". Terminals soliconed in, star washers and plated nuts holding everything together nice and tightly, and silver solder finishing the leads.




For the first time since I started this build, I pulled the box off the shop cart I've been building it on (grey thing in the background). Being that this was plywood rather then MDF, I was able to move it by myself. If this were MDF, I'd probably be dead under the thing right now. All that said, I will not use cheap plywood again in the future. It caused so many problems, and has a sloppy finish..even the layers are peeling up the more it's handled!! Oh, and insulation tape added to all parts that will be in contact with the baffle (even the bracing, for equal pressure all across).




I'm POSITIVE this thing is pretty air tight. When I placed the baffle on top, as it slipped into place, the woofer puffed out on it's suspension! That's a good sign I believe! Unfortunately, my stainless, self drilling (though I still pre-drilled), self counter sinking, hex-head screws were a little too short for this much baffle. With the thick insulation tape all around, I just couldn't get enough grip with 1.5" screws to pull the lid on, even with the weight of the woofer, and 80lb battery backup holding it all down. I'll have to pick up some nice 2.5" deck screws tomorrow, and I'll be giving it a test run tomorrow night!




Wish me luck!
 

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Thanks for all the effort in sharing the build with us mate.

Top marks :)
 

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Discussion Starter #59
Thanks for all the effort in sharing the build with us mate.

Top marks :)
It's my pleasure! I'm also geeked to be the first 21" build in the Exodus section!

Not many questions in this thread...so either I'm explaining things well, or nobody cares. :dontknow:

On my way home from work tonight I'll be picking up some quality stainless deck screws, locking the top down, and trying to figure out how to get this beast up stairs and into the home theater. I'll probably carry the box and the baffle/woofer up separately to make things easier on me.


Now, it's been over a year since I ran REW in my living room/home theater. I'm not even sure where I stored the tools to do so, or what laptop I connected the gear to. So I'll have to re-learn that with some guidance from those in the REW section. But I will take measurements. Unfortunately (well, fortunately from the financial standpoint), I sold my Wicked One folded horn with the JL Audio subs in there, so I can't do a side by side comparo with measurements. I'll have to just use last years measurements, of which I'm pretty sure I have a screen cap in my photo gallery. Honestly, I hold the folded horn in high regards. If I had 10" drivers that covered the sub-30Hz range better, I'd probably be keeping it. So the M-21 has to really impress me!

I'll have to look up how to configure my EP2500 to bridged Mono as I've been running the folded horn with one channel to each driver (but still mono). I also bought the cable components to make a better cable between my Onkyo 805 and the EP2500 (I have some mild ground loop noise), but that can wait till after I give the Maelstrom-X 21" a good run through. Ah! Speaking of which, I guess I'll need to run Audyssey again! Looks like some fun times tonight! :hsd:
 
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