Posted by Duke on December 23, 2005 at 00:59:27:
In Reply to: Has anybody ever tried to mass load the base cavity posted by Penguin on December 22, 2005 at 20:11:41:
I used to have eight 25-pound bags of lead shot (the original shot canvas bags were each inside a zip-lock freezer bag, liberally wrapped in duct tape, and for aesthetics hidden inside two thick black socks). I put 100 pounds on top of each backplate, and the difference was somewhere between small and imaginary at best.
Later I tried putting 50 pounds on top of each upright panel of my M-1s, at the outer corners. That improve the imaging, probably by lowering the frequency at which the panels would tend to rock back and forth a bit (imagine the panel as an upside-down pendulum). I kept the other 50 pounds on the backplates more for ballast than anything else.
Replacing the stock carpetglider feet with pointy cones made a bigger difference.
The A-1's panel-to-base junction is more rigid than that of the M-1, so I'd expect weighting the backplate and/or the panel to make less of a difference.
Duke