Constrained layer damping / thin metal / fibreglass layer

[RobWells]

Hi All,

I posted this in the loudspeaker section as this seems more about construction technique than specific car audio issues.

I'm in the process of doing a car audio installation, and the 'usual' solution to panel flex in the doors is to add a layer or two of dynamat (or equivalent) on the outer door skin, with another layer on the inner door skin between the door and the door trim panel.

What I'm asking is whether you guys think a couple of layers of fibreglass added to the outer door skin, then covered with deadening sheets will give a significant improvement ?. I have the fibreglass sheet / resin lying around so it won't cost me anything but time.

I'm thinking that the fibreglass will have a different resonant frequency to the door skin so they should damp each others resonances and give a decent improvement, but I don't think I've ever read of anybody doing this.

What d'ya think ?

Rob.

[GM]

Greets!

I think that a max impedance mis-match is desirable, so adding the FG 'fill' should reduce the Dynamat's effectiveness since it will be mass loading the door skin.

GM

[RobWells]

So that would explain why people don't do this then.!

Thanks GM.

Rob.

[454Casull]

It might be beneficial if you had the Dynamat in between the door and the fiberglass.