"William Sommerwerck"

It's been done. William Michael Watson Dayton-Wright built conventional
dynamic speakers with bags of SF6 in the woofer box.

** For what advantage ?

The speed of sound is about half in SF6 but that is no help in a sealed box
where resonance depends only on the stiffness of the volume of gas trapped
behind the woofer.

The smaller the volume or the larger the woofer, the stiffer it becomes.

He got clean bass to below 16Hz from a small cabinet.

** Really ?



..... Phi