Find a shooting range or gun store in your area. The shot comes in various sizes. I would get the smallest (more dense) that they have. It usually comes in a 25lb bag and is not cheap. You'll be surprised at just how small a 25lb bag is!
The Arros are pretty small (that's an understatement) so you probably won't need too much to fill the compartment. I would DEFINITELY go with the shot instead of sand. Since these are floor-standers and the fill material is actually going INSIDE of your speakers, I wouldn't mess around with sand at all. The granuals are too fine and could find their way into your speakers.
Think about going to the beach. The sand finds its' way into every orophus. Don't mess with it!
The Arros are pretty small (that's an understatement) so you probably won't need too much to fill the compartment. I would DEFINITELY go with the shot instead of sand. Since these are floor-standers and the fill material is actually going INSIDE of your speakers, I wouldn't mess around with sand at all. The granuals are too fine and could find their way into your speakers.
Think about going to the beach. The sand finds its' way into every orophus. Don't mess with it!