Best way to decrease the internal volume of a sealed speaker?

Sorry for the late reply.. the expandable foam will dry with a smooth surface, unless you mess with it. It will be flexible, though, so take Erik's advice into account. I'm not sure how flexible materials would effectively increase the internal volume, but Erik doesn't tend to talk out his butt and has much experience building speakers.

That said, nothing wrong with experimenting.

If you do use 2x4's, considering using blue tack to hold them in place until you're happy with the sound. Then, if the cabinets are unpainted MDF on the inside, consider wood glue. It is very strong when gluing wood together (duh) and would not be flexible like silicone, which could add too much damping. Or maybe you need the extra damping of the silicone.. I suppose you could start with silicone and, if it's over damped, cut it out and use wood glue.

By the way, those cabinets look quality. Let us know how it all turns out

Ozzy

Seal the sawdust and glue with something...varnish the inside a couple of coats or so.Tom

toddverrone, cliffkhz, theaudiotweak,

Thank you for the help and the posts.
The woofer I will be using will be located very close to the bottom of the cabinet. Because of this it will be near impossible to place wood at the bottom of the cabinet.

The upper inside top appears to be the best place for any type of cabinet internal volume reduction.
So, at this point, I am first going to try the Styrofoam route. I think I can glue a chunk of it to the inside top. If this rattles or comes loose then the next plan would be to change the front baffle so that the woofer can be raised up and allow the installation of wood or bricks etc. at the bottom.
The front baffle is 1" thick and cutting openings again for the ribbon tweeter and the woofer is not an easy task. 

ozzy