On my sub the mdf is 1 1/2" thick around the driver for the top 3 layers and 1" thick down the rest of the tube.
And at high volumes the cabinet vibrates quite a bit. As far as I can tell it's not audible but then it's pretty loud at that volume. At moderate volumes I can just barely feel the wall of the tube vibrate.
While I have no problems with the overall performance I am a little disappointed the tube resonates as much as it does. I should've gone thicker on the walls. Maybe 2" would've been more ideal. There's no fancy bracing inside either. I don't think the upward firing woofer suffers. But then I'm rocking the servo amp!
Next I'm gonna build the OB subs.
