36" THT Low Profile, Warning lots of coffin pictures

[El dillo]

I am building a THT low profile, i will replace my two diy peerless xls 10" subs, hoping to get better low frequency impacts for movies. They say bigger is better... right? so decided to build the 36" version.
I´m halfway through the build.

Couldn´t find the PL glue here in europe but i found on the forum that someone recomended the Everbuild Lumberjack 30min Wood Adhesive gel. It´s a Polyurethane gel glue and it seems to work well.

[El dillo]

First i got confused about how many bracers to use with this width, the plans says 3 sets wider than 25". But more rigid is better so i used 4, have anybody had any problems with panels resonating?

[Grant Bunter]

Looking great so far

To many braces is way better than not enough!
Panel resonance is not always detectable, and it can account for a loss in output of around 3dB...

[El dillo]

Ok good to know , i was more worried about unwanted noise.
I think im going to try a different design for the cover...

Maybe laminate ply and mdf (and braced), I also want to use T-nuts and countersunk holes for screws.

[El dillo]

How much could the internal volume of the closed chamber vary from the original design (36") without affect the sound for the worse?

[Radian]

Stay away from MDF. It doesn't have enough rigidity for these applications.

[Grant Bunter]

How much could the internal volume of the closed chamber vary from the original design (36") without affect the sound for the worse?

It shouldn't vary at all, other than the tolerance of panels making it 1/16" to 1/8" out.
Stick to the plans.

The chamber size in the plans is the size the chamber needs to be...

[caddylackn]

That is going to be heavvvy

What driver are you using? What are you going to use for an amp?

[El dillo]

It shouldn't vary at all, other than the tolerance of panels making it 1/16" to 1/8" out.
Stick to the plans.

Ok, it just seems like the cover in a 36" needs more stabaility, Bracing it may be enough then.

That is going to be heavvvy

What driver are you using? What are you going to use for an amp?

I surely hope it will not exceed the wheight of my old concrete sub enclosures (80kg) i almost broke my back everytime i had to move them.
I think a sack trolley will do the job.

i will use the Dayton Audio RSS390HF-4 driver with an extra gasket connected to one channel from a stereo amp (upgrade comes later) and the crossover is in the AV- reciever.

[El dillo]

6/2 bracers

I was thinking it needed the airflow so i made all of the panel 6/2 bracers with an cutout (for the driver), the bracers that are not oppsite the driver should these be without?

[Tom Smit]

You can leave those 6/2 braces as is because it does not matter. The only reason for the notches is so that the driver will not contact the braces.

[El dillo]

Test fitting the other side panel...

Some misalignment to fix
I also had to do some planing and grinding on the width panels because of height differences.
It was all cut at the workshop

[El dillo]

Some Plastic Padding will fix it.
The other panels was almost perfect, but some had to be re drilled.
Bought 4 tubes of glue, almost 2 full that would be enough for the rest.

[El dillo]

haven´t found any leaks so far...

Hope this will work



Made the lid larger, i will do some routing later when the lid is in place to get exact fit.

I wonder if the connection panel need to be sealed with silicone or if it will be airtight just with a rubber seal.

[caddylackn]

I would add some braces perpendicular and in between those lid braces that would stiffen it up along the other axis. While those braces stiffened up the lid in the short direction, in the long direction you could get flex. If the final placement of the speaker will put the access panel in contact with the ground with the speaker throat pointing up, the extra bracing wouldn't be needed. The only way it could flex would be to lift up that 200 lb speaker

I wonder if the connection panel need to be sealed with silicone or if it will be airtight just with a rubber seal.

Follow the leakage test in the plans. It is easy to hear air leaks in the access panel with a hose to your ear. You can always use the rubber seal, test it, if it leaks seal the entire perimeter gap of the access with clear latex caulk. It goes on as white, and dries clear. It is paintable, water clean up, and easy to cut cleanly if you ever need the access panel off again. Silicon, makes a mess and isn't paintable. It is hard to cut cleanly, it wants to tear.