Try placing a brass weight, like those offered by Mapleshade, on top of the Black Cube.
The weights can sometimes be found used in the Audiogon listings. Or, you can often find brass weights (paper weights, scale weights, etc) on E-Bay.
The weights can sometimes be found used in the Audiogon listings. Or, you can often find brass weights (paper weights, scale weights, etc) on E-Bay.