T39 20"

[whines]

Got two layers of paint in the mouth after putting tape down to keep the to-be-glued areas clean. It's annoying how far you can see up there if you look at JUST the right angle. :J One more coat and I'll call it good.

The mouth braces are now assembled...and then I remember that I forgot to put handholds in them. Dangit! I -should- just put handholds in the edge, and it's not too late to do that, I just don't like the way it looks. Which is silly, but. Hmm.

Panel 11 installed on one sub. I didn't realize you could turn the clamps around like that until I saw someone do that in a build log, very handy!

[whines]

Second panel 11 installed, PL scraped.

Mouth braces scraped and sanded, given the first coat of paint. Eventually I realized that they'd stand up on their own, started getting less paint on my hands at that point.

[whines]

Used bondo to fill in the center of the braces, used a file to get it in the right shape (thanks to whoever mentioned that!) and sanded it down. Two applications of bondo would have made it perfect, but...it's going to be facing the wall.

Cut the final side 1/2" large, matched the nice edge up with the open side and used a pencil to mark all the parts I could reach. Covered joints-to-be with masking tape in the mouth area and prepainted it, two layers of Kilz.

Drilled some holes along the boards I'd marked, test fit it and predrilled holes for the screws to fit in. On the corners I left the screws in, poking out just far enough to settle in the holes for alignment.

Put a good bead of glue on the edges, got my partner to help me set them in place and they're on!

[whines]

Lots of time for working on these babies over the three day weekend, even with goofing off thrown in!

After a day of drying, took the screws out and trimmed the second side, then did a roundover on all the edges.

Let the drivers burn in with 35hz at 10 volts for half a day, wired out of phase so they were pretty quiet.

driver-burnin.jpg (21.07 KiB) Viewed 2061 times

Bondo'd the screw holes, sanded, bondo again, sanded. Then first coat of paint. Inside, thank goodness, Texas is still too hot.

Used chisel to scrape the remaining PL away from the braces and other crevices in the mouth, sanded it down some, and gave it (and the outside) a second coat of paint.

Got of of those folding dollies from Harbor Freight for moving them around between the driveway for sanding and the living room for painting--I like it a lot (the big-ish wheels go over bumps great) but the black plastic leaves marks on the pristine white paint. Guh. For now I'll cover it with cardboard, but I need to treat these with kid gloves until I can get a protective coat of glossy acrylic on them.

I need to get the drivers in to leak test before I get any crazier with the finishing...

[howiez]

Got of of those folding dollies from Harbor Freight for moving them around between the driveway for sanding and the living room for painting--I like it a lot (the big-ish wheels go over bumps great) but the black plastic leaves marks on the pristine white paint.

I bought the carpet ones, thinking that plastic would be an issue, though the wheels and overall quality of the plastic ones seemed better.

Nice looking build!

[whines]

A little more sanding, a little more paint, and the last cuts of the build to make the access panels!

Leak tested (sans panels so far) and everything seems good.

[HugoMack]

Thanks for this thread, which I'm really enjoying.

Still trying to decide how wide to go.

I'd thought of 24 inches. My Jack 12 Lites are very loud, and don't need subs for most of my gigs (live band). So my logic was to match the subs to the optimal width of T39 so that when they are used the system is at its maximum potential. We could even get it all into my Volvo estate (as we use IE monitoring).

But having the T39's 4 inches slimmer does save vital space.

How was your system when using the 15 inch T39's?

[whines]

How was your system when using the 15 inch T39's?

Zero complaints with them, honestly, although my requirements are pretty low. I've never been able to let them rip at full volume without getting scared first.

I feel like the 20" ones are edging out of the comfortably handle-able solo range--at least to someone of my not-young age with back issues. Once the wheels are on it it'll be a cinch to roll around but every time I pick it up or turn it over to paint I'm reminded that I should be asking for help.

The 15" ones I'm fine with as long as I'm careful.

Definitely, definitely put in the handles as shown in the plans, they're so comfortable and solid-feeling that it's wonderful!

[HugoMack]

I'm wondering what the optimum width would be for use with Jack 12 Lites - using the subs to take up all the bottom end load.

I definitely re-think my intention to make 24's. But if anyone has words of wisdom regarding this, gratefully received. It would be pointless to lug around 24's or 20's if I'd need two more Jack Lites or DRMs to match the subs maximum output.

[Tom Smit]

Looking at the SPL Charts for the T39 and the Jack12, the T39 fills in the bottom octave. Hugomack, I think you would need a 3012LF in T39s just to keep up with your J12s, and they should be close to 20".

[HugoMack]

Thanks Tom.

I was thinking about 24 inch using the Lab 12, which displaces 659cc so is over 2x that of the 3012LF although 3 times heavier...

Bill talks very firmly about displacement being the critical factor, so I'm still not sure about judging how wide to make the T39s so as not to over-match my Jack 12 Lites.

I may be missing it, but I can't see any charts for the Lab 12. However, from what I can discover, the Kappalite 3012LF is better at around 80Hz, whereas the Lab 12 does a lot better at 40-50. Therefore I might be better off using the 3012LF for subbing my Jack 12 Lites for live band use....?

So if using 3012LFs, I'd need to build T39's at least 20 inches to match the Jacks...

SOrry to hijack this thread. I'll open a new one in the appropriate section.

[Tom Smit]

The Lab12 matches the 3012LF in output in the case (horn sub), so Xmax is not a point in this case. The 3012LF got ridiculously expensive in NA a few years ago, so the Lab12 became an option.

[whines]

As I understand it, the tradeoff between the 3012 and the Lab12 is dollars vs. pounds (of weight), and that the performance is similar.

[HugoMack]

I expect you've seen this, on page one of the T39 building notes:

"The 3010LF Vd 305cc, so it runs about 4dB louder than the BP102 or Delta 12 LF. The Lab 12 Vd (&12c) is 659cc, so it’s equivalent to three BP102 or Delta 12LF, justifying its weight and price. When comparing various drivers don’t look at the watts, look at the displacement."

Driver price doesn't bother me, as the time and effort of making the cabs makes me want the optimum result. Weight is definitely a factor though, although less so for the subs.

[Bruce Weldy]

I expect you've seen this, on page one of the T39 building notes:

"The 3010LF Vd 305cc, so it runs about 4dB louder than the BP102 or Delta 12 LF. The Lab 12 Vd (&12c) is 659cc, so it’s equivalent to three BP102 or Delta 12LF, justifying its weight and price. When comparing various drivers don’t look at the watts, look at the displacement."
.

That statement is pertaining to the other two drivers. The 3012LF is the same output as the Lab.....according to Bill and are both limited to the same voltage.