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post #1 of 44 Old 02-03-2013, 02:29 PM - Thread Starter
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It has been a long time since I have done a project, so let's get started, shall we? smile.gif

This project will involve three of these:



and one of these



and a lot of this



all wrapped up in a nice wrapper.


I started cutting wood today, and using my DowelMax to help line things up once glue-up happens. This will be large, so I will need everything lined up quickly and easily once glued. The wood is 23 3/4" x 48", and I am not cutting them down, just to give you an idea.

I got the dowel holes drilled into the four sides



Then did a test run



It lined up perfectly.

Progress will be slow, but I will keep it updated. Next issue is to cut 19 1/4" holes......the Jasper Jig isn't big enough....darn.
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post #2 of 44 Old 02-03-2013, 04:13 PM - Thread Starter
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It's already looking like a proper coffin.Just doing a test run to make sure everything fits and lines up well.

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post #3 of 44 Old 02-03-2013, 06:43 PM
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What type of bracing?
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post #4 of 44 Old 02-03-2013, 06:57 PM
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Look ghreat. I'm also curious about the bracing. It must be like fort knox!

Blasting brown notes for 10 years and counting!

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post #5 of 44 Old 02-03-2013, 07:07 PM
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what kind of passive are those?
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post #6 of 44 Old 02-03-2013, 09:25 PM - Thread Starter
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Quote:
Originally Posted by audiovideoholic View Post

What type of bracing?

Quote:
Originally Posted by N8DOGG View Post

Look ghreat. I'm also curious about the bracing. It must be like fort knox!

Stay tuned
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post #7 of 44 Old 02-03-2013, 09:26 PM - Thread Starter
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Quote:
Originally Posted by financethis View Post

what kind of passive are those?

Those are 21" PR's from Kevin Haskins. I don't recall if they were called Exodus or Maelstrom or ???
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post #8 of 44 Old 02-03-2013, 09:46 PM
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Are you finally doing that 8th order PR BP design with the 5100? Please say yes.
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post #9 of 44 Old 02-03-2013, 09:59 PM - Thread Starter
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Quote:
Originally Posted by Ricci View Post

Are you finally doing that 8th order PR BP design with the 5100? Please say yes.

6th order bandpass, and YES!
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post #10 of 44 Old 02-04-2013, 01:24 AM
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"What the....? indeed!

This project came out of nowhere. Interesting.

My Dual 18" LLT subs 120dB down to 10hz

 

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post #11 of 44 Old 02-05-2013, 03:45 PM
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Looks like a Mal-21 PR, as rare as an albino gorilla.
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post #12 of 44 Old 02-05-2013, 04:00 PM
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This looks like a fun project!

Kevin was supposed to sell me a bunch of those long ago but suddenly the PMs from him mysteriously stopped. frown.gif
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post #13 of 44 Old 02-05-2013, 08:57 PM
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Look forward to seeing progress and results.... Good luck....

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post #14 of 44 Old 02-09-2013, 01:18 PM - Thread Starter
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First off--if you don't know yet, this is a blatant rip-off of Mark Seaton's BMF design he did for that audio-company-who-shall-not-be-named many years ago. His design used a 15" driver with 18" PRs. Mine will use an 18" driver with 21" PRs. It's a VBMF! Mark knows how to design a sub, so the BMF was as compact as you could make it, and looked great. I don't know how to design a sub, so I made mine oversized so that I could add something solid to the insides if the volumes turned out to be too great, especially in the front chamber. Building it will be much easier than messing with the weights on the PRs and the volumes of the chambers.

Second--damn you Menards for no longer carrying baltic birch. I picked up this "Tigerply" that also has 13 layers in the 3/4" ply. Make that 13 layers of crap. Luckily I will be wrapping the whole thing in MDF so it will hide my shame.

Third--The Jasper Jig goes to 18 15/16" and I needed 19 1/4" for the PRs. What to do? Drill another hole in your Jasper Jig, of course! I just measured out 9 5/8" from the bit and drilled my own hole with the drill press and a 1/8" bit. Drilled like butter. The pic shows my test drilling--I had to go out further for the final hole.


Once the jig was done, I got all the driver holes routed and mocked up the box.



Next up, bracing
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post #15 of 44 Old 02-13-2013, 10:04 AM - Thread Starter
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I got some work done in the last few days--I can't glue it up all at once, so a few pieces at a time. Got the outsides glued up.



Got the inner mount for for the 5100 installed after drilling for the screws and installing the gasket. Added some bracing as well.




Still trying to figure out the rest of the bracing. Should be able to pop the top on soon, then laminate the whole thing with 1/2" MDF.
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post #16 of 44 Old 02-25-2013, 06:46 AM - Thread Starter
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Slow progress, but progress nonetheless. I got all the bracing done using a mix of ply scraps, Baltic Birch scraps, PL Premium, Titebond, pocket screws, etc.



Once all the bracing was set, I popped the top on, which went on perfectly since I had set it up to use dowels previously. I used Bowclamps to go across the spots where there was cross bracing. They worked fantastic.



Once this cures, I can go ahead and install the drivers and get to testing the different weights on the PR's. When that is set, I will pull the drivers out, laminate the entire box with 1/2" MDF, and either paint or veneer. I have set the big PR's into their cutouts--they are just ridiculously large!
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post #17 of 44 Old 02-25-2013, 07:16 AM
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Why are you going to laminate the box with 1/2" MDF? Wouldn't you rather use some real wood vener? Or is the 1/2" MDF strictly for making the enclosure more ridgid?
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post #18 of 44 Old 02-25-2013, 07:29 AM - Thread Starter
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There are several reasons I use the MDF. I like the surface better than this crappy ply for either painting or veneering. It adds rigidity. It seals. It countersinks the drivers.
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post #19 of 44 Old 02-25-2013, 10:59 AM
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Quote:
Originally Posted by Fatawan View Post

There are several reasons I use the MDF. It adds rigidity. It seals.

MDF is less stiff than ply, though better damped

Noah
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post #20 of 44 Old 03-13-2013, 02:14 PM - Thread Starter
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Slow but steady progress here. Getting the last of the MDF layered on. Let me reiterate that what is known as TigerPly is the most evil ply made by man. I was so happy to see the last of it disappear beneath the MDF. It truly is garbage.




Had to make a circle cutting jig to make the 21 1/4" cut outs for the PRs, and that worked perfectly.




I have the lead shot to use as weight in the PRs. Washers are just too unwieldy to work with. They would stick out a long way and it would take a ton of them to get the job done. I will mess with weight using the lead shot, then gorilla glue the shot in permanently when I settle on an exact weight.
I also ordered a gallon of Duratex as that is good enough for my dark theater, and this thing is too huge to veneer affordably.
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post #21 of 44 Old 03-13-2013, 02:21 PM
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If the 21" Exodus PR's are anything like the 18" wouldn't the max extra weight they can carry safely be about 1600 grams which is what is included in the mass kit? I don't have any 21" PR's but I do have the 18" and I remember there be a warning about using more than that.

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post #22 of 44 Old 03-13-2013, 05:37 PM - Thread Starter
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I do not have any washers from the mass kit. I bought these off of someone else and there were no washers included. All I have is a bolt and nuts/lock washers for each one. I bought some large fender washers and they were not very heavy--it would have taken a ton to load the PRs. I do not know the max weight on these. I have tried to get Kevin Haskins to answer questions, but no luck so far. I was just going to wing it. I will have to revisit my model now that it's time to test the drivers. If I recall correctly, I was going to add ~1800g to the rears and only 400 or so to the front.
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post #23 of 44 Old 03-19-2013, 07:16 AM - Thread Starter
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A couple coats of Duratex and it's now time to load the box with drivers.



The final volumes turned out to be about 10.2 cf for the rear chamber, and 2.8cf for the front chamber. That front chamber will need some solid filler to reduce the chamber volume to up the tuning point. My model abilities are limited. I was using WinISD with three different models going at once. I was using 2 PR models, one for each chamber, and a model for a 6th order bandpass. I made all volumes the same, and would change tuning points on the PR models and see how it affected a 6th order bandpass model. It is very crude but gives me a rough idea of how the entire box will perform with all the outputs combined. I am going to start out with about 2000g on the rear PR's, tuning at ~18Hz, and 400g on the front PR, with a volume of ~1.5cf, and tuning at ~56Hz. It's a start at least. I am not sure how I will measure and sum the three outputs from the PR's(any tips Ricci?), but one step at a time.
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post #24 of 44 Old 03-19-2013, 10:22 AM
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Wow, what a beast! Neat build.
Q's;
1) What is the expected weight of this when done with drivers/PR, 150lbs or so. You add handles to move a box this size?
2) So many people use Duratex, it's $55+ gallon, for HT use where you move the sub into its spot and there she sits is that overkill?
If you had to advise a value black flat paint (in the $25/gal range) to use instead of Duratex what would it be?
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post #25 of 44 Old 03-19-2013, 11:20 AM - Thread Starter
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Quote:
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Wow, what a beast! Neat build.
Q's;
1) What is the expected weight of this when done with drivers/PR, 150lbs or so. You add handles to move a box this size?

I'd guess closer to 200 pounds--I just add one large son and we lift it up and move it. There is only one spot where it will fit in the theater, so it's a one shot deal! I get him to help me spin it around in the shop so I can work on the various sides. Shop is in the basement, so we don't have far to travel

2) So many people use Duratex, it's $55+ gallon, for HT use where you move the sub into its spot and there she sits is that overkill?

This is my first Duratex use. Two coats on this monster probably use less than a 1/3 maybe a 1/4 of the gallon. It goes a long way. Try the trial size http://store.acrytech.com/Speaker-Cabinet-Texture-Coating-Duratex-Roller-Grade-Trial-Size-Kit-Black.html I don't know if it is overkill--it is easy to apply, gives a tough coat to the box, and should go a long way for more projects.

If you had to advise a value black flat paint (in the $25/gal range) to use instead of Duratex what would it be?

I have never actually done a flat black sub now that I think about it!
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post #26 of 44 Old 03-22-2013, 10:58 AM - Thread Starter
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Here is the 5100 all snugged in to its resting spot as seen through the front chamber



If I left the front chamber at its current volume, the tune on the front chamber would be way low, somewhere in the low 40's. So, I needed to remove some volume from that front chamber. Foam to the rescue!



I think I can beat down to the volume to somewhere near 1.5cf with this combo. With 400g on the PR, that would push my front chamber tune to ~57Hz and make for a pretty combination with the rear chamber 17 Hz tune
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post #27 of 44 Old 04-03-2013, 04:31 PM - Thread Starter
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Measuring out the lead shot



My trusty old scale from my veterinarian days keeps coming in handy!

I think I am going to bag the bolts and washers completely and just Gorilla Glue the shot into place. The inserts are kind of crooked, don't look all that sturdy, and my MDF rings I made as giant washers can't go in very well since the inserts are set in at odd angles, which makes the bolts skewed. Uggh.
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post #28 of 44 Old 04-08-2013, 04:16 PM - Thread Starter
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DONE!

Not without drama and trauma, but it is at least all assembled. It turns out that the round tube where the weights screw in will hold exactly 1870 grams of lead shot plus the gorilla glue to keep it in place. Oh, and gorilla glue foams up far more than I remember! It was a fountain held in check with duct tape. This what the rear PR's looked like when it had all cured.



The front PR only had 400g of lead shot added, so I used way too much gorilla glue and let it foam as much as it wanted.




Somehow, there is a stray piece of shot rolling around in a dust cap or somewhere else close by. I am hoping it wedges itself in somewhere and is never heard from again. Murphy's Law would counter that and say that it will shake and rattle and bother me forever more.

Here is the final product in its home. Those are 15" LMS5400's in the background to give you an idea of scale.



Tonight I will get it hooked up and at least fire it up for a listen and leak check.
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post #29 of 44 Old 04-08-2013, 04:39 PM
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Wow, that is a monster!

I am looking forward to your listening impressions.

Very unique and cool build, I can't think of another build like it.

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post #30 of 44 Old 04-08-2013, 08:08 PM - Thread Starter
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Crazy amounts of high quality bass. That's my first impression after listening to some multichannel Talking Heads. I only had a few minutes, but it made for a huge grin on my face. This was using this single sub in my theater where I normally have EIGHT subs going! Measurements to come when I can....
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