4x T48 and 4x OT12 build

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dlv
Posts: 87
Joined: Sun Jun 09, 2024 6:39 pm
Location: Prescott AZ

4x T48 and 4x OT12 build

#1 Post by dlv »

It has officially begun.

Just picked up the BB today.
IMG_5164 Large.jpeg
The amp rack is coming together too. (Still need to put a caster board on it)
IMG_5169 Large.jpeg
And I've got a bunch of Eminence drivers on the way. 4x KL3015LF for the T48s, 4x DL2512/N210T HF for the OT12s. Seems the F151M-8s are on the way out. The 210s are a bit pricey but I like the 2" voice coil and sensitivity they have.

I've got a bunch of prep work to do before actually cutting pieces for cabs. I'm building a cutting table and, well, I have to clear space in my shop to do this thing! It's a bit of a mess. :roll: But the BB was on sale so I jumped on it. 20% off, saved me close to $300. (wood is stupid expensive!)

I plan to chronicle the adventure here. Sure to have some questions along the way but I've already learned a TON reading this forum.

Huge thank you to all of you for the wealth of information here.

-Dave
Builds:
4 x 24" Titan 48's loaded with 15's
4 x OT-12's with CD horns
Considering:
Simplex 10/12 wedges
Simplex subs
Simplex bass/guitar cabs

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Seth
Posts: 3008
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
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Re: 4x T48 and 4x OT12 build

#2 Post by Seth »

Awesome Dave! I look forward to progress reports.

One thing I'll mention before you get too far is, back in the day we all used to use T nuts or hurricane nuts and bolts to secure the drivers. It seems like the beefy and professional way to go. However, the plans no longer recommend them, and it's for good reason. I highly advise you stick to the plans and use the recommended screws to secure all your drivers. Save the money and save yourself the potential headache down the road.

Have fun!
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

dlv
Posts: 87
Joined: Sun Jun 09, 2024 6:39 pm
Location: Prescott AZ

Re: 4x T48 and 4x OT12 build

#3 Post by dlv »

Not a lot to report.
Amp rack has wheels now and I just need to wire it up. I'll paint the caster board when I do the speakers.
IMG_5185 Large.jpeg
Had some other shop projects I needed to work on to clear space to start this build. Did that and now have the BB in the shop and built my cutting table. Pretty much ready to start cutting panels. Santa in the brown truck comes tomorrow with all the drivers!
IMG_5189 Large.jpeg
Builds:
4 x 24" Titan 48's loaded with 15's
4 x OT-12's with CD horns
Considering:
Simplex 10/12 wedges
Simplex subs
Simplex bass/guitar cabs

dlv
Posts: 87
Joined: Sun Jun 09, 2024 6:39 pm
Location: Prescott AZ

Re: 4x T48 and 4x OT12 build

#4 Post by dlv »

Man I know it's said over and over again here but ... I'll put it in my build thread case someone like me is reading it.

Before you cut ...

1) Read the plans.
2) Read the plans.
3) Read the plans.

And when you've completed steps 1-3, Read the plans again! Every time check every part you need to cut before starting cutting.

I have been using CutList and painstakingly extracting details from the plans creating a spreadsheet of every panel and brace to track what I need to cut. This morning before I was going to start cutting, I reviewed it all one more time and found mistakes!!! 4 Titans involves over 100 parts to cut out! I had missed a panel in my list (x4). Luckily for me I had duplicated another as well so things are working out materials wise. In fact I may have bought extra. But that's ok. I'm betting this isn't the only mistake I'll make.

In fact I'm rethinking my plan to cut all the parts for all 4 subs in one go. Now I'm considering if I should cut just the parts for one sub and fully assemble it before cutting the parts for the other 3. Just to be sure I'm not making the same mistake 4 times over. Less efficient in both time and materials, but safer. Hmm.
Builds:
4 x 24" Titan 48's loaded with 15's
4 x OT-12's with CD horns
Considering:
Simplex 10/12 wedges
Simplex subs
Simplex bass/guitar cabs

User avatar
Bill Fitzmaurice
Site Admin
Posts: 28916
Joined: Tue May 02, 2006 5:59 pm

Re: 4x T48 and 4x OT12 build

#5 Post by Bill Fitzmaurice »

By all means do one first. You will find adjustments have to be made, if only because plywood thickness isn't exact. It's also a learning experience with the first cab. After that any additional are easy.

dlv
Posts: 87
Joined: Sun Jun 09, 2024 6:39 pm
Location: Prescott AZ

Re: 4x T48 and 4x OT12 build

#6 Post by dlv »

100%. Thanks Bill. Definitely what I'm going to do. FWIW turns out (after running this plan in CutList) expected material utilization isn't that different anyway.
Builds:
4 x 24" Titan 48's loaded with 15's
4 x OT-12's with CD horns
Considering:
Simplex 10/12 wedges
Simplex subs
Simplex bass/guitar cabs

dlv
Posts: 87
Joined: Sun Jun 09, 2024 6:39 pm
Location: Prescott AZ

Re: 4x T48 and 4x OT12 build

#7 Post by dlv »

What little time I had over the weekend I spent finishing up the wiring in the amp rack. It's ready to gig now.

Finally started cutting yesterday. Doesn't look like much but this is a solid half day in the shop.
IMG_5191 Large.jpeg
I'm going slow and following Bill's suggestion to cut and assemble one cab first. Then do the rest. I'm glad I am because I'm getting a list of questions how they'll actually need to be cut to fit as I cut panels. I'm writing questions and notes on each panel so when it comes time to fit it, I'll capture the results in my build notes and have a better idea when cutting for the rest of the cabs.

Btw I sprung for one of these for a saw sled. https://www.amazon.com/dp/B073PGP96S Man I'm glad I did. The clamp kit https://www.amazon.com/Kreg-Tool-KMS752 ... B0747T9MHJ is ridiculously another $23 but it is a must IMO. I know I could have made a sled cheaper but this thing is really nice. The track gives very nice cross cuts on a 4' sheet and my table saw is set up to final trim the inside panel dimension of 23" and I'm just leaving it there so every interior panel is exact.

:feedback: A question about DuraTex, I'm about to place an order. Do folks really get 200 sq in per gallon or is that a best case? Do you find a single coat is enough? I'm thinking a coat of cheap black primer will help with that. Any consideration for what kind of primer?

For 4x 24" T48s and 4x OT12s my maths say 40 sq ft per T48 and about 14 sq ft per OT12. (all 6 sides) That's 216 sq ft.

I'm hoping to put grills on all cabs so I'm thinking of painting the interior with something in flat black, maybe the primer if it covers well. Good or bad idea?

If I don't use DuraTex on the throats maybe I can squeeze all 8 cabs out of 1 gallon? But I don't want to get caught short and I'm also planning to make some speaker pole tops to put the OT12's on and I can coat them to match. I should also build a couple sub coupler V panels. Be nice to DuraTex those too so everything matches.

So probably going to order 2 gallons and lay it on good and heavy. Have plenty for other parts and of course touch ups.

Thanks!

-Dave
Builds:
4 x 24" Titan 48's loaded with 15's
4 x OT-12's with CD horns
Considering:
Simplex 10/12 wedges
Simplex subs
Simplex bass/guitar cabs

Bruce Weldy
Posts: 8539
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: 4x T48 and 4x OT12 build

#8 Post by Bruce Weldy »

:feedback: A question about DuraTex, I'm about to place an order. Do folks really get 200 sq in per gallon or is that a best case? Do you find a single coat is enough? I'm thinking a coat of cheap black primer will help with that. Any consideration for what kind of primer?
Use flat black paint as primer. It's the cheapest paint you can get at HD or Lowes...so, that's a plus. Put on a couple of coats of that. It doesn't have to be pretty as the Duratex will cover it.

I don't see why one gallon of Duratex won't do everything and still have some left over. I've done tons of speakers, boxes, racks, etc. And I'm only finishing up my second gallon.

Roll it on evenly finishing with a light touch to keep the nibs down. Do four cabs at a time....by the time you finish one coat on all four, you can start back over with the second coat. Or, do all the cabs and let totally dry and start over the next day. With a good primer coat(s), the duratex will go a long way.

When you put it away, put a sheet of food plastic wrap down inside the bucket and press it down right on top of the duratex. It will stay usable for months/years like that. Also, if you are going to take a break from painting, even overnight. Wrap the roller in plastic wrap and it will stay wet. I only clean my roller after the whole project is finished and it cleans right up with a sprayer on a garden hose.

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."

dlv
Posts: 87
Joined: Sun Jun 09, 2024 6:39 pm
Location: Prescott AZ

Re: 4x T48 and 4x OT12 build

#9 Post by dlv »

Thanks Bruce! Ok 1 gallon it is. Great tips on the plastic wrap. I've done that on paint cans but never a roller. Never thought of that!
Builds:
4 x 24" Titan 48's loaded with 15's
4 x OT-12's with CD horns
Considering:
Simplex 10/12 wedges
Simplex subs
Simplex bass/guitar cabs

Bruce Weldy
Posts: 8539
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: 4x T48 and 4x OT12 build

#10 Post by Bruce Weldy »

And you definitely want to use these.....

https://www.acrytech.com/product/4-text ... ck-refill/

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."

dlv
Posts: 87
Joined: Sun Jun 09, 2024 6:39 pm
Location: Prescott AZ

Re: 4x T48 and 4x OT12 build

#11 Post by dlv »

This might be a minor detail but I’m OCD about these things.

What are folks using to round off hand holds in the top and bottom of T48 full back cabs?

I’ve got a 3/8 in radius round off bit that looks good for the outside but the inside (except for where I the 1/4 round goes) is still pretty sharp. Once one side is rounded can’t use a round over on the other side. I guess I can just sand it some but wondering if any one has found a good solution.
Builds:
4 x 24" Titan 48's loaded with 15's
4 x OT-12's with CD horns
Considering:
Simplex 10/12 wedges
Simplex subs
Simplex bass/guitar cabs

User avatar
Bill Fitzmaurice
Site Admin
Posts: 28916
Joined: Tue May 02, 2006 5:59 pm

Re: 4x T48 and 4x OT12 build

#12 Post by Bill Fitzmaurice »

You can round both sides, you just need to clamp or screw a piece of plywood to the already rounded side for the router base to follow.

dlv
Posts: 87
Joined: Sun Jun 09, 2024 6:39 pm
Location: Prescott AZ

Re: 4x T48 and 4x OT12 build

#13 Post by dlv »

Ok why didn’t I think of that? I can just flip the template over to the other side.
Builds:
4 x 24" Titan 48's loaded with 15's
4 x OT-12's with CD horns
Considering:
Simplex 10/12 wedges
Simplex subs
Simplex bass/guitar cabs

dlv
Posts: 87
Joined: Sun Jun 09, 2024 6:39 pm
Location: Prescott AZ

Re: 4x T48 and 4x OT12 build

#14 Post by dlv »

Ok pic heavy update.

Things have been slow from a build perspective. Spending a lot of time on jigs, templates and just figuring things out. SO glad I followed Bill's advice to go all the way through one cab first, then build the others.

Built a small parts jig using MicroJig stuff.
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The jig at work.
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Minor setback when momentarily set my router on the table saw then proceeded to trip on the cord and SMACK it went on the concrete floor. There were plastic bits that didn't survive and it wouldn't come on. Damn. :wall: But thankfully I was able to mess with it and get it going. Just broke some plastic around the switch and it worked once I got it out. Thankfully didn't land on the bit and bend the shaft or something.

A wise friend once said; "Nothing ever fell off the floor".

Spent a lot of time figuring out just how I want to do the hand holds. Experimented around with several iterations on a router template. There may be better ways but this is what I came up with. Note using the Forster bit to remove some material really helps. If you've got a better router and better bit you might not need to but this helped with my wimpy router. I'm using a 1/4" trim bit with a bottom bushing so template has to go underneath the work.

The template is made so the edges is EXACTLY aligned with the edge of the top. Add a piece of 1/2" scrap when aligning with the back. The template cuts the hole so there's exactly the right clearance inside for the 1/4 round. I have a center line in the template that lines up with the centerline of the hole on the workpiece. I line up the template with clamps then mark the hole. Remove the template and use a slightly smaller Forster bit to remove some material. Clamp a sacrificial piece underneath to prevent blow out.

Realign the template edge & centerline and clamp it. Flip it over so it's on the BOTTOM. Screw it on from the top with flat head drywall screws and be sure the heads are below the surface so they don't interfere with the router. Now trim to the template.
IMG_5198 Large.jpeg
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Here's a hole rounded off with a 3/16" bit.
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Test fitting the Top & Back to see how it's looking.
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Then I realize I may not have left enough room between the handles for my NL4 connectors. So I check and it's really tight but I think they'll work. I had just picked an arbitrary distance (6" from the side) to center the handles because it looked good. Should have thought that one through a bit more.
IMG_5206 Large.jpeg
If only I'd set the handles 1" each way to the side I'd have 2" more there and be fine. I'll probably do that on the remaining 3 cabs even though this one will be different.

My plan is to inset the NL4 connectors so they're just flush and put a backer behind that for the screws to go into. This is me experimenting with that inset and test fitting in some scrap. Again, using Forster bits. A 2" in this case for the inset and a 1" for the center hole.
IMG_5205 Large.jpeg
There's really not much room behind panel #9 up in the top of the cab. But that seems like the most desirable (for me at least) place to put them.

Seems like I've been doing a lot and have yet to crack a tube of PL! Got a few more gluing jigs to make that'll fill the rest of today then (hopefully!) start gluing tomorrow.

-Dave
Builds:
4 x 24" Titan 48's loaded with 15's
4 x OT-12's with CD horns
Considering:
Simplex 10/12 wedges
Simplex subs
Simplex bass/guitar cabs

dlv
Posts: 87
Joined: Sun Jun 09, 2024 6:39 pm
Location: Prescott AZ

Re: 4x T48 and 4x OT12 build

#15 Post by dlv »

There's no doubt this jig is gonna be square. :lol:
IMG_5217 Large.jpeg
Builds:
4 x 24" Titan 48's loaded with 15's
4 x OT-12's with CD horns
Considering:
Simplex 10/12 wedges
Simplex subs
Simplex bass/guitar cabs

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