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Radian's T18 Build
Posted: Tue Sep 02, 2025 1:30 am
by Radian
Took hiatus from building T48's this past year to knock out a T18 for our new Compass. The original plan was a slim Truck Tuba using an HL-10A, and place it just behind the front seats in the rear passenger area. However, once she got used the four doors and keeping stuff in/on the rear seats rather than in the diminutive hatch area, the trunk came under strong consideration.
We took measurements, made a mock up and determined a classic T18 would be the perfect weapon for this CUV. That meant ordering the latest iteration of the MCM 55-2421 from Newark and commencing with the sawdust.
I had a can of WetLook left over from nearly a decade ago. I swore if I ever used the stuff again, I'd use a Preval sprayer (I've no cup gun, nor large compressor) instead of brushing this stuff on. But an immediately failed attempt to send this goo through these hopeless contraptions had me schlepping it on with a foam brush, once again. Looks like hell, but keeps the untreated cone from succumbing to mold and moisture. Note: Preval sprayers require very thin paints to function at all...a simple coat of clear poly would work better in hindsight
Re: Radian's T18 Build
Posted: Tue Sep 02, 2025 1:40 am
by Radian
This is 9 ply BB from a purchase about 4 years ago, before prices flew to coop for building materials. Remember when we thought $40 a sheet for this stuff was pricey?
Standard width and using 7.5mm 5 ply for the bracing means dados around the interior. Baffle milled out and prepped for Hurricane nuts to be epoxied in place. Tuba18 rear chamber is very tight space wise. Orientation of the bolt holes can make or break the install of the driver later on. As such, the design requires access from both sides just to get your mitts in there.
Re: Radian's T18 Build
Posted: Tue Sep 02, 2025 1:42 am
by Radian
Fitting up the remainder of the horn path. Keeping everything as damn square as possible.
Re: Radian's T18 Build
Posted: Tue Sep 02, 2025 1:45 am
by Radian
All glued up, cured, and screws removed. Corners and access holes routed. Onwards to filling holes, leveling imperfections, and sanding, then milling the access cover panels.
Re: Radian's T18 Build
Posted: Tue Sep 02, 2025 1:51 am
by Radian
Filled and sanded. Experiments with Duratex showed that a quality latex primer greatly reduces the required quantity of the final coating, in addition to improving the overall cosmetic appearance. Holes to attach the access cover panels had to be CAREFULLY drilled to prevent splitting the rear chamber panels.

Re: Radian's T18 Build
Posted: Tue Sep 02, 2025 1:54 am
by Radian
Placing the driver in its final home. Super tight at first glance, but Bill's got the dimensions just right to still allow a driver and hand to get in there to tighten things down.
Re: Radian's T18 Build
Posted: Tue Sep 02, 2025 1:57 am
by Radian
Access cover panels installed, terminal cup plumbed in, and everything screwed down. Couple coats of Duratex and it's ready to make some serious thump.
Re: Radian's T18 Build
Posted: Tue Sep 02, 2025 2:07 am
by Radian
Hero shot in an attempt to make it look as imposing as a Titan or larger Tuba perhaps. FWIW, 18 inches cubed isn't exactly THAT small, but next the Klipsch La Scala in the background, well.

And a closeup of the texture I was able to get out of the last bit of "Roll-on grade" Duratex I had from years back. Two coats and the foam rollers from Parts Express are a must in order to pull off this look. Thing pounds way above it's size. Get's stupid-loud, quick. Will have video and other data once we get it installed in the car. ....now it's back to building the remaining T48's
Re: Radian's T18 Build
Posted: Tue Sep 02, 2025 9:05 am
by Bruce Weldy
Great build!
Congrats.
Re: Radian's T18 Build
Posted: Tue Sep 02, 2025 11:43 am
by Seth
Nice. Well done! (as usual)
Re: Radian's T18 Build
Posted: Tue Sep 02, 2025 9:23 pm
by Tom Smit
Good to see you back!
Re: Radian's T18 Build
Posted: Wed Sep 03, 2025 3:43 am
by AntonZ
Wow, that looks totally lovely. Great finish with the roller. The woodwork looks quality as well. I love the dado way of building for the folded horns. I know it is more work but the way things just slide in place and stay there brings me both satisfaction and peace of mind. I built my T18 the same way. Mine got double braces, since I used 3/8" 9mm ply. Yes it is more work. Yes, it still is my most satisfying build to date. Thanks for sharing, you will enjoy this one.