Another OT12 build

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Bruce Weldy
Posts: 8301
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: Another OT12 build

#16 Post by Bruce Weldy »

Chris_Allen wrote:
Bruce Weldy wrote:Looks like the newest plans don't show a different baffle for the 3012HO and the other drivers as far as the slots.
Yep, they disappeared in the 2011 set of the plans and aren't present in the JArray version either.
I got my first set plans in 2011, but before the change. Oh well......

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."

ctmullins
Posts: 195
Joined: Thu May 13, 2010 9:05 am
Location: MS Coast

Re: Another OT12 build

#17 Post by ctmullins »

Ok, then, that explains my confusion. Thanks for the clarification Bruce and Chris! :cowboy:
-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)

commander_dan
Posts: 461
Joined: Sun Feb 16, 2014 7:19 pm
Location: Perth, Western Australia

Re: Another OT12 build

#18 Post by commander_dan »

ctmullins wrote:So why exactly does it need to be sealed off?
I'd thought about this also when I built my otops, and sealed them with PL anyways. I figured since they're high power cabs, you want all the strength and rigidity you can get... not sealing the top hats could also be a potential rattle zone.
Built:
6 T30 (24", 3012LF)
2 OT12 (MA, 3012HO)
2 T24 (18", 3010LF)

Running:
DCX2496
XTi 2002
XTi 4002
TRAKTOR Z2
TECHNICS 1210 Mk5's

ripNdeb
Posts: 512
Joined: Fri Sep 24, 2010 4:57 pm
Location: Eureka, CA
Contact:

Re: Another OT12 build

#19 Post by ripNdeb »

ctmullins wrote: So why exactly does it need to be sealed off?
Because it's a horn. Can't have air leaks just like the subs can't have air leaks. Folks even plug the 1/4" jacks if they're not using them.
2X OTop 112, 3012HO, melded - 2X T39, 27", Lab 12 - XF 212 - 4 DR250, 2 melded, 2 straight
2 20" T39 3012LF - WH10 - WH8 - in the shop - 2 more 20" T39s
http://saltandlighteureka.org still need a trailer :)

ctmullins
Posts: 195
Joined: Thu May 13, 2010 9:05 am
Location: MS Coast

Re: Another OT12 build

#20 Post by ctmullins »

Made tiny bits of progress now and again over the last weeks. Got the horn panels trimmed flush - so glad I made the table saw sled!

Image

Cut out my phase plug pancakes from scrap, using a hole saw:

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Cut out my driver anchors using my state-of-the-art compass:

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Finally installed them tonight!

Image
-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)

ctmullins
Posts: 195
Joined: Thu May 13, 2010 9:05 am
Location: MS Coast

Re: Another OT12 build

#21 Post by ctmullins »

Eight side panels with port handles cut and routed, and installed. I even got all of the handles pointing the right way round!

Image

At this point I was curious about weight. I had been guessing that each finished cab would come in at between 40 and 50 pounds. So I grabbed one of the completed (well, almost completed; I still have to do the access panel flanges) shells and put it on my digital bathroom scale. It didn't even light up. So I weighed myself with and without the cab, and the difference is 19 pounds. Add a couple for flanges and piezos, and no more than eight for the 2512 and filters, and that's under 30. Wow! Oh, I forgot the nice beefy steel top hats. Okay, so maybe 32. That's fantastic! :hyper:
-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)

ctmullins
Posts: 195
Joined: Thu May 13, 2010 9:05 am
Location: MS Coast

Re: Another OT12 build

#22 Post by ctmullins »

Been doing the fiddly bits - handle half-rounds, access panel flanges. It's tedious, and takes up all my clamps. :conf:

Also putting together my piezo cutting jig. It's nearly time! :hyper:
-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)

ctmullins
Posts: 195
Joined: Thu May 13, 2010 9:05 am
Location: MS Coast

Re: Another OT12 build

#23 Post by ctmullins »

Alright, so here's the piezo cutting jig I threw together. It runs in the T-track, and one side is for the 90-degree cuts and the other is for the 45-degree cuts. A bungee cord holds the tweeters in position so that my fingers don't have to be so close to the blade. It didn't take me too long to figure out that I can cut two tweeters in a single pass on the 90-degree side!

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And here's my very first melded array all glued up. Looks great in the pic, but I assure you, there are hideous gaps all in it. I'm trying to dissolve some of the offcut with the glue to fill in those gaps. It'll be mostly hidden behind a grill anyway.

Image
-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)

ctmullins
Posts: 195
Joined: Thu May 13, 2010 9:05 am
Location: MS Coast

Re: Another OT12 build

#24 Post by ctmullins »

Oh my - does everybody's first melded array come out looking this hideous?

Image
-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)

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Bill Fitzmaurice
Site Admin
Posts: 28619
Joined: Tue May 02, 2006 5:59 pm

Re: Another OT12 build

#25 Post by Bill Fitzmaurice »

ctmullins wrote:Oh my - does everybody's first melded array come out looking this hideous?
Pretty much. Put masking tape over the joints, add cutoffs from the piezos to thinned cement to tint it black, fill the joints from the back. After it sets pull the tape, smooth the joints wet sanding with 240 grit paper.

ctmullins
Posts: 195
Joined: Thu May 13, 2010 9:05 am
Location: MS Coast

Re: Another OT12 build

#26 Post by ctmullins »

Haha, thanks Bill, thought it was just me! I'll follow your advice and report back. :hyper:
-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)

ctmullins
Posts: 195
Joined: Thu May 13, 2010 9:05 am
Location: MS Coast

Re: Another OT12 build

#27 Post by ctmullins »

Worked great! Doesn't look perfect from the front, but that's okay, since I'm going to use grills. But the array is structurally very sound now. Got it wired up too.

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Also got four crossovers wired up. I put the woofer section on the left and the tweeter section on the right. The inductors are spaced five inches edge-to-edge, seven center-to-center, which should be plenty, right?

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And thanks to whoever it was that suggested using terminal strips - that made the whole thing go a lot faster, and neater too! Only one solder point on each one, where all those thingies tie in on the tweeter side... 8)
-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)

ctmullins
Posts: 195
Joined: Thu May 13, 2010 9:05 am
Location: MS Coast

Re: Another OT12 build

#28 Post by ctmullins »

Not had a lot of time for these lately, but I am making slow progress. I got the piezo array brackets installed, and I got my grills cut out. I'm going for something slightly more stylish than flat grills along the front edge:

Image

Now that the grills are cut out I can glue in little cleats at each corner to screw them to, at the proper angle (it's not perpendicular). :D
-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)

ctmullins
Posts: 195
Joined: Thu May 13, 2010 9:05 am
Location: MS Coast

Re: Another OT12 build

#29 Post by ctmullins »

Back at these again after a bit of a hiatus. I have a bad habit of getting 90% done with something and then getting sidetracked... :bash:

Got all four sanded with 80 grit, nice and smooth and even now. Drilled the access panels for jacks. Cut up some cleats for grill mounting.

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Glued 'em in (love my big spreader clamps!).

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One in each corner, and two in the center for the straight array cabs.

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I eyeballed the angle; came out pretty good!

Image

Ready for Duratex!
-todd

5 and 8 string bass | SansAmp | Crown | 2 x J110
2 x W8 panel-mount
2 x T39 24" 3012LF
4 x OT12 2512 melded (finally done!)

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LelandCrooks
Posts: 7244
Joined: Thu May 04, 2006 9:36 am
Location: Midwest/Kansas/Speaker Nirvana
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Re: Another OT12 build

#30 Post by LelandCrooks »

I really like the grilles. Nicely done.
If it's too loud, you're even older than me! Like me.
http://www.speakerhardware.com

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