Cascade "Quiet Kote" Damping Spray?

Per PE...
"Quiets vibration and rattles in vehicle body panels, doors, and plastic and fiberglass trim, or can be applied to the outside of a vehicle (fender wells, underbody, etc.)."

If you're building a sheet metal sub, this would be the stuff to use. If you can make straight, square cuts and use sufficient glue in construction, a plywood or MDF box would not benefit. A couple hardwood dowels between panel centers will be far more effective.

Have fun,
Frank

might be good for longer ports or end to end resonances in sono builds. I might give some a shot on my 6" inch pvc ports for the exact build I just mentioned!!!!

How is it going to do that? Resonances in long ports or tall sonos are acoustic, due to the length of the cylinder and not mechanical resonances in the structure.

That spray is for damping thin sheet panels.

in my particular sono, I can hear a resonance coming from the pvc vibrating since I didnt support it on the far end away from the port. damping the pvc OR supporting the free end of the port should take care of it.

How do you know that the resonance is due to the tube (physically) vibrating, and not a cavity resonance due to it's length? Modelled and measured to determine?