A pair of OT112s and some T39s
-
- Posts: 26
- Joined: Thu May 24, 2012 8:18 pm
- Location: Joplin, MO
A pair of OT112s and some T39s
Well, I've lurked the forums for a couple of years, bought plans in January and started building a week or so back.
Started with the OT112s since they seemed smaller and easier to learn on. So far, that seems like a good decision. Got the structural stuff done last week and moved on to prepping the T39s. Assembly starts tomorrow!
Don't have many pix at this point simply because I was too busy scratching my head - plus, I was usually covered in sawdust, PL or both!
My wife has decided that since I'm a "woodworker" now, we can tackle new floors and a few other projects after this saga is complete. Actually looking forward to it, simply because I like this stuff!
Never built anything on this level before and am grateful for Bill's excellent plans and all the support here.
Here's a few shots...
Started with the OT112s since they seemed smaller and easier to learn on. So far, that seems like a good decision. Got the structural stuff done last week and moved on to prepping the T39s. Assembly starts tomorrow!
Don't have many pix at this point simply because I was too busy scratching my head - plus, I was usually covered in sawdust, PL or both!
My wife has decided that since I'm a "woodworker" now, we can tackle new floors and a few other projects after this saga is complete. Actually looking forward to it, simply because I like this stuff!
Never built anything on this level before and am grateful for Bill's excellent plans and all the support here.
Here's a few shots...
Re: A pair of OT112s and some T39s
Well done so far! Enjoy your build. And, yes, the skills can transfer over to house reno's.
BTW, welcome!
BTW, welcome!
TomS
-
- Posts: 3495
- Joined: Sat May 13, 2006 9:56 pm
Re: A pair of OT112s and some T39s
You're now a cabinetmaker
if I was you I'd build them a little off square or you'll be making new kitchens, not so much fun.

BAT10, Bad Auto Tuba. Reverse folded TAT to fit JBL 1014D, 350W driver, voltage limit unknown.
-
- Posts: 6912
- Joined: Mon Nov 28, 2011 11:12 am
- Location: Ilfracombe Queensland Australia
- Contact:
Re: A pair of OT112s and some T39s
Looking great so far!
Wanting to see this rig when it's all done...
Wanting to see this rig when it's all done...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...
-
- Posts: 26
- Joined: Thu May 24, 2012 8:18 pm
- Location: Joplin, MO
Re: A pair of OT112s and some T39s
I do have a question about damping material.
According to my plans, I'll (lightly) fill the area from the baffle forward with poly-fill - like pillow stuffing. Behind the baffle, convoluted foam is recommended and that is what I'd originally planned to use... then I had a thought...
Does anyone have any experience using fiberglass ceiling tiles as damping material? They're about 1/2-3/4" thick, compressed fiberglass insulation. You'd probably have to peel the surface layer off, but that's nothing. 1 or 2 thicknesses would be pretty easy and I think I could have an infinite supply of the material just for the asking.
Also, there's no mention in the plans for damping material in the T39...?
Just curious. Thanks.
According to my plans, I'll (lightly) fill the area from the baffle forward with poly-fill - like pillow stuffing. Behind the baffle, convoluted foam is recommended and that is what I'd originally planned to use... then I had a thought...
Does anyone have any experience using fiberglass ceiling tiles as damping material? They're about 1/2-3/4" thick, compressed fiberglass insulation. You'd probably have to peel the surface layer off, but that's nothing. 1 or 2 thicknesses would be pretty easy and I think I could have an infinite supply of the material just for the asking.
Also, there's no mention in the plans for damping material in the T39...?
Just curious. Thanks.
- Michael Ewald Hansen
- Posts: 638
- Joined: Tue Aug 16, 2011 10:43 am
- Location: Denmark
Re: A pair of OT112s and some T39s
I can't say about the fiberglass insulation, as im not familiar with it.rmediacraft wrote:I do have a question about damping material.
According to my plans, I'll (lightly) fill the area from the baffle forward with poly-fill - like pillow stuffing. Behind the baffle, convoluted foam is recommended and that is what I'd originally planned to use... then I had a thought...
Does anyone have any experience using fiberglass ceiling tiles as damping material? They're about 1/2-3/4" thick, compressed fiberglass insulation. You'd probably have to peel the surface layer off, but that's nothing. 1 or 2 thicknesses would be pretty easy and I think I could have an infinite supply of the material just for the asking.
Also, there's no mention in the plans for damping material in the T39...?
Just curious. Thanks.
There is no damping material needed in the T39

Authorized Builder - Denmark
Check out the BFM Facebook page
Check out the BFM Facebook page
-
- Posts: 6912
- Joined: Mon Nov 28, 2011 11:12 am
- Location: Ilfracombe Queensland Australia
- Contact:
Re: A pair of OT112s and some T39s
If there is any chance that the driver in action would make fibreglass fibres be emitted from the cab, that would be bad...
Just stick with what Bill recommends in the plans.
Just stick with what Bill recommends in the plans.
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...
- Bill Fitzmaurice
- Site Admin
- Posts: 28916
- Joined: Tue May 02, 2006 5:59 pm
Re: A pair of OT112s and some T39s
Rigid fiberglass is an excellent damping material, but not the least bit user friendly. You'd be reminded of that every time you put your hands through the ports to pick up the cab and stray fibers leave you itchy for the next day or so.rmediacraft wrote:
Does anyone have any experience using fiberglass ceiling tiles as damping material?
Re: A pair of OT112s and some T39s
One solution to the shedding nature of fibreglass is to use a dilute solution of PVA in a flower misting spray to lilghtly seal in the outer surface. It doesn't restrict the material from doing it's job. I used it on acoustic panels in my home studio with some success. You can also use acoustically transparent material such as "Voile" or muslin to face fibreglass to the same effect. Seems like more hassle than it is worth inside a cabinet though.
-
- Posts: 8538
- Joined: Fri Nov 27, 2009 11:37 am
- Location: New Braunfels, TX
Re: A pair of OT112s and some T39s
Gee, don't make this so hard....
Just go buy some mattress topper, cut it up and glue or staple it in - it's that easy.
The port holes aren't cut yet in the picture....
Just go buy some mattress topper, cut it up and glue or staple it in - it's that easy.
The port holes aren't cut yet in the picture....
6 - T39 3012LF
4 - OT12 2512
1 - T24
1 - SLA Pro
2 - XF210
"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."
-
- Posts: 26
- Joined: Thu May 24, 2012 8:18 pm
- Location: Joplin, MO
Re: A pair of OT112s and some T39s
Thanks Bill, for your reply. Clearly, I hadn't thought it through all the way...
Mattress topper it is!
Didn't build yesterday, spent some kid time instead.
Had a photo shoot this afternoon, but got several hours in and make a little progress.
The first T39 looks pretty gnarly inside (and out), but it's PL'd to the max and square. Nothing some sanding and paint won't fix... I think.
Probably gonna be a couple of days before I can do more. Another shoot in the morning and some lake time after that.
Thanks again everyone.

Mattress topper it is!
Didn't build yesterday, spent some kid time instead.
Had a photo shoot this afternoon, but got several hours in and make a little progress.
The first T39 looks pretty gnarly inside (and out), but it's PL'd to the max and square. Nothing some sanding and paint won't fix... I think.
Probably gonna be a couple of days before I can do more. Another shoot in the morning and some lake time after that.
Thanks again everyone.
Re: A pair of OT112s and some T39s
Better than porn 

-
- Posts: 26
- Joined: Thu May 24, 2012 8:18 pm
- Location: Joplin, MO
Re: A pair of OT112s and some T39s
Well, it's been a while since I posted any updates. The build has gone much slower than I wanted - mostly because of life. Summer, a house full of kids and me on Mr. Mom duty every other day doesn't help either!
Anyway, got the subs buttoned up and I'm currently plugging holes and sanding for finishing. Sure wish I'd paid more attention to the drying PL. It's virtually impossible to get off. Yes, I know the chisel trick, but it only goes so far. Sandpaper is almost useless. Through the build, I've discovered that about 30-60 minutes after application is the perfect time to clean up your PL mess. Slides right off the wood with a sharp chisel. It's a beautiful thing. Unfortunately, it's a little too late for that. Sigh...
Bolted a woofer in a cab last night to check for air leaks. So far so good. Too hot (105F) in the garage to work today, so I got around to unboxing my crossover components for the OT112s. I've attached a pic of my proposed layout if anyone cares to give it the once-over. You'll just have to imagine the solder joints. I could do the dual-board layout in the plans, but a central location makes more sense to me... for whatever that's worth.
Starting to feel like I might actually finish this project... maybe even this month!
Anyway, got the subs buttoned up and I'm currently plugging holes and sanding for finishing. Sure wish I'd paid more attention to the drying PL. It's virtually impossible to get off. Yes, I know the chisel trick, but it only goes so far. Sandpaper is almost useless. Through the build, I've discovered that about 30-60 minutes after application is the perfect time to clean up your PL mess. Slides right off the wood with a sharp chisel. It's a beautiful thing. Unfortunately, it's a little too late for that. Sigh...
Bolted a woofer in a cab last night to check for air leaks. So far so good. Too hot (105F) in the garage to work today, so I got around to unboxing my crossover components for the OT112s. I've attached a pic of my proposed layout if anyone cares to give it the once-over. You'll just have to imagine the solder joints. I could do the dual-board layout in the plans, but a central location makes more sense to me... for whatever that's worth.
Starting to feel like I might actually finish this project... maybe even this month!
- Attachments
Re: A pair of OT112s and some T39s
If you could stand your little inductor farther away from the big inductor, it will be better yet. The layout seems right as far as I can chase it.
TomS
-
- Posts: 3495
- Joined: Sat May 13, 2006 9:56 pm
Re: A pair of OT112s and some T39s
Should the right side +IN be labled -IN?
BAT10, Bad Auto Tuba. Reverse folded TAT to fit JBL 1014D, 350W driver, voltage limit unknown.