Questions about pyroboards

[antmaster12]

So i am building a pyroboard (3d rubins tube) and need a material that will protect the speakers from catching on fire but not absorbing the sound. Any ideas?

 

[musical marv]

So i am building a pyroboard (3d rubins tube) and need a material that will protect the speakers from catching on fire but not absorbing the sound. Any ideas?

What is this exactly?

 

[ex_bubblehead]

http://en.wikipedia.org/wiki/Rubens%27_tube

2d version here: http://hackaday.com/2014/04/19/the-pyro-board-a-two-dimensional-rubens-tube/

The driver is never in the flame so no fireproofing is needed.