T39 maintenance

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Tom Smit
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T39 maintenance

#1 Post by Tom Smit »

Well, it has been 10 years since I built my air of BP102 loaded 20" T39s and I decided to check them out. I had never put full power to them nor did full sweeps because, back then I had to burn the midnight oil to get them completed on time, and the few times that I did use them it was for lower volume events. I did have them running near full tilt with a pair of TLAHPros, outdoors, a couple of months ago, for test and tune, and, I did notice that something seemed to be off with the subs. So, a few weeks ago I started at 40hz, gently cranked it up until I was near 30v. The first sub had air leaks at the Speakon connectors that are installed in the mouth. I pulled them out, applied a goodly amount of hot glue in and reinstalled. That took care of the air leaks. Yay! :hyper:
The next sub had a nasty rattle at 40 hz with 12v applied, or 50hz with 18v. I could get it to rattle if I wrapped #5 panel behind the driver so, I figured I must have a loose brace or two. Multiple holes were drilled and eventually I found the braces. I drove 2" screws to lock in the braces, installed the driver, ran the test, and.... it's still there. :wall: Now what!? Well, I thought of a member from a long time ago... Harley Dear. So, out came my hand saw
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Tom Smit
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Re: T39 maintenance

#2 Post by Tom Smit »

Then, it was time to cut the side panel free.
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Re: T39 maintenance

#3 Post by Tom Smit »

Everything seemed fine except for this jumper, so I glue in a small piece of foam underneath.
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Re: T39 maintenance

#4 Post by Tom Smit »

That was not the answer! I found some gaps in the small braces so I applied adhesive on any brace that I could find, and the retested. It doesn't rattle until I hit 27v. I am happy with that. I had it going at 50hz on 27v and my wife about 50ft away, in the house, and she said it was too much and hurting her ears (she IS sensitive that way).
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Tom Smit
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Re: T39 maintenance

#5 Post by Tom Smit »

I should add that those two cabs are the only two that I never really tested. All the other cabs that I have built were stress tested to make sure that they would perform properly.
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Seth
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Re: T39 maintenance

#6 Post by Seth »

First time I've ever seen the boards "Active Topics" go blank from inactivity since I've been a member here. Tom to the rescue! An enjoyable read I might add. I've always wondered how to get the side off, never thought long enough to think of using a hand saw. I don't think I've seen one in person in over 20 years! Great job Tom. Bummer it didn't get completely resolved, but sometimes good enough is good enough. Well done brother.
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

Bruce Weldy
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Re: T39 maintenance

#7 Post by Bruce Weldy »

Did you remove the covers and check the drivers? I'll bet they can be tightened after 10 years. Plus, this happened to me and my driver was shredded. It worked at low volume, then started farting out with more power.

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."

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Tom Smit
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Re: T39 maintenance

#8 Post by Tom Smit »

Indeed, I did Bruce. It was because of you that I thought that I should check the screws on the drivers. The screws did move a titch.
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Re: T39 maintenance

#9 Post by Tom Smit »

Seth wrote: Sun Sep 28, 2025 10:13 pm First time I've ever seen the boards "Active Topics" go blank from inactivity since I've been a member here. Tom to the rescue! An enjoyable read I might add. I've always wondered how to get the side off, never thought long enough to think of using a hand saw. I don't think I've seen one in person in over 20 years! Great job Tom. Bummer it didn't get completely resolved, but sometimes good enough is good enough. Well done brother.
Thanks Seth! I try! :D
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Joman116
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Re: T39 maintenance

#10 Post by Joman116 »

That was a good read. Thanks for sharing.
2x20" Titan 39 loaded with Eminence KAPPALITE 3012F
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Tom Smit
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Re: T39 maintenance

#11 Post by Tom Smit »

Joman116 wrote: Tue Sep 30, 2025 11:58 am That was a good read. Thanks for sharing.
You're welcome!
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