New Build of Old-style T39s

[lancemhorsley]

Nice work!

[Bruce Weldy]

Today's work began with another process that really helps to keep you focused and cut down on sawdust being tracked into the wifely domain.....it's called The Harley Effect.

Went to work on cutting the bottoms and the back to accept the casters and the jack plate.

After cutting the bevels on all of the horn panels all that was left was the braces. These can be a pain in the butt, but here's how I do 'em (notice the two buts in a row? Literary genius.)

First draw 'em out. Then cut 'em to length.

Next, I used a little quick made jig/sled to cut the angles. I first stumbled on this when making WH10s last year.

Take a piece of scrap plywood and set your rip fence....doesn't really matter where, just a little narrower than the scrap. Run the scrap through the saw. Now you have a straight edge that is perfectly in line with the blade.

Now, with the brace on the sled - sight down the line you drew and line that up with the edge of the sled. Use of couple of scrap blocks to make a jig for repeat cuts. Or, If you like, you can just shoot some brads in the piece to hold it in place, then pop 'em off after you cut.

You get repeatable cuts and it beats the heck out of trying to free hand 'em with a jig saw or circular saw.....and it's a lot safer too.

[Bruce Weldy]

Here's post cut....

And.....tada!!!!!

Other than drawing lines for the the brace placement on the panels and gluing up the driver spacers and the access cover cleat....I'm pretty much done until my t-nuts and bolts come in the mail.

[miked]

Your brace/angle cutting jig is a fantastic idea. Duly noted for my Titan build. Thanks for sharing your tricks!

[shawn_g]

Looking good!

[Bruce Weldy]

Glued up the driver spacer and the access cover cleat this morning. While giving it a little drying time, I took a little weight out of the big braces.

Then it was time to drill the holes and install the hurricane nuts. I know most of you now use the recex screws for the Neo drivers, but I'm building the old style and you just can't get a screw at the bottom of the speaker. For those of you that will use hurricane or T-nuts, Harley had a great idea how to keep 'em from turning.

I took a piece of scrap and drilled an oversized hole. Dropped in the nut, used a little hand clamp to keep it set and drilled a small hole in the flange. T-nuts are easier...you can just put a screw in the gap.

Here's one installed in the baffle.

Then is was epoxy over the edge of the flange and the screw. This is also a good time to draw alignment lines for the interior braces - a lot easier to line 'em up later.

These aren't going anywhere. Thanks for the idea, Harley.

[Bruce Weldy]

Time to start gluing up panels. Once again, I'll extol the use of the W-braces. Easy to make and much more exact than a guide board for keeping big panels square.

First just attach the top clamp, leaving the bottom loose so you can move it into place. Once you have it lined up, put on the bottom clamps. Then drive screws up into the panel. Take 'em back out, take off the bottom clamps and move the panel back. Apply adhesive and put it back. Replace the clamps and re-drive the screws into the pre-tapped holes. Instant alignment.

Then install the baffle. This keeps everything really square now. Used brad nails to tie the baffle to the top - screws to the side.

Installed the next two panels before calling it a night....

[miked]

Looking fantastic, Bruce! It's cool to see that though you're using the old plans, you're incorporating newer tips and tricks like the t-nut no-spin fix and the one piece access cover brace. I'll do the same when it comes to build my Titans.

BTW: In that last pic, the bottom two panels, the ones that form a "V"; are they just PL'd together or are there brad nails toenailed in there too?

[Bruce Weldy]

BTW: In that last pic, the bottom two panels, the ones that form a "V"; are they just PL'd together or are there brad nails toenailed in there too?

Yep, all the panels get shot with a few brads.

Sure you don't want to build T39s? We'd have one hell of a herd!

[miked]

Honestly, I've contemplated T39s, but I already have one brand new 3015LF that's been sitting here for more than a year. While I could sell it and put the funds towards 3012LFs, I'd have to take a small loss/eat the shipping.

Plus, the slightly lower freq response of the T48 is appealing to me since I'll be using them for DJ work vs. live sound reinforcement the majority of the time.

Thanks for letting me know about the brads; you know how I like to take notes before I start a project.

[DJPhatman]

Thanks for letting me know about the brads; you know how I like to take notes before I start a project.

Then pay very close attention to Bruce's W shaped clamping braces, and how they are used. Use the right adhesive, PL Premium, and dampen the plywood slightly just before gule-up time, as the PL needs moisture to cure and expand. And, we all know how dry it is in Texas!

Watch and learn, and plan to mimic his build. T48s are the same process, just larger scale, as the T39s.

but I already have one brand new 3015LF

This tells me you will only build one to "start". You are almost done with 4 OTop12s. You will need at least 4 T48s, so build them all at once. Do whatever you have got to do to afford the other 3 drivers. Talk to Leland Crooks, at Speakerhardware.com, he can help you get all the parts you need, and even some you might not have thought of.

[Bruce Weldy]

And, we all know how dry it is in Texas!

Yeah....it's dry here. I'm playing golf today - it'll be 70 degrees and I'll be sweating buckets.

[miked]

One T48? ONE? Oh no way, my friend! Horns work best in pairs, so I was planning on 2, v-plated of course, to start. The one 3015LF I have, I actually bought to build another bass cab with, but found I don't need it. The one I built (a fEARful...look it up ) is more than enough for me.

I know that two T48s will be much better than the two 18" direct radiating/ported subs (no name but they have Neo drivers) than I have now. I do know that I'll need 4 T48s to keep up with 4 OTops, particularly outdoors. It will take time to save up the scratch for 2 more drivers, plywood and all the incidentals, so 4 eventually, 2 to start.

[Bruce Weldy]

Got a little work done today....figured I'd post while some glue was setting up...


I didn't document all the rest of the panels. It's pretty straightforward and there's no special tips that I can think of, so let's get to the back. Up 'til now, the braces can push the panels a little bit here and there - but you don't want that on the back. To make sure I kept the back straight after installing it, I dry fitted the bottom with screws and the W-brace holding it all square.

Now you can check out whether the braces are gonna sit in there nice and tight without bowing the back. They needed some straightening, so I made quick work of in on this combo spindle/reciprocating belt sander:

After getting 'em squared up, I did something different this time. It's always tough to get these big braces in without 'em wanting to slide around. I shot three brad nails through the back to use as a shelf for the brace to rest on. Then I could hit it with a couple of brads on the inside panel, then a couple through the back. Much easier than last time.

[Bruce Weldy]

Now, on to the caster wells.

They are made up of a 1/2" face, 2x4 backer, and a couple of corners (cutoffs from the speaker spacer) to close the hole.

It takes a little work to get the angles right.

First put in the bottom corner piece flush with the opening. Then the plywood fits on that, then the 2x4 backer, and finish with the other corner on top.

There's a little protrusion past the bottom - no problem, that gets trimmed flush. This is kinda' nasty looking, but I like to smear some PL in the cracks. It'll be all cleaned up.