Thoughts on "solid" spikes and GRAMMA-like products:

On a carpeted surface, which of these three situations would transfer the most kinetic energy to the sub-flooring? Which situation would transfer the least?

1: A very stiff table is placed on the carpet upside down so that the weight of the table is spread out across the fibers leaving them uncrushed and with some flexibility left in the carpet and carpet pad underneath. A bowling ball is dropped from one meter above the tabletop such that it lands on the exposed side of the tabletop near one end.

2: The same table is turned right side up and left to sit for a month. The pointed legs crush the relatively small amount of carpet and padding under them leaving no flexible material between the end of the leg and the sub-flooring. The bowling ball is dropped from one meter above the tabletop and lands on the very stiff tabletop near one end.

3: The same table, either right side up or up side down, has placed under each corner the following - a one foot square of ¼” plywood; on top of that, a good bath towel folded to 2” thick; next 2” thick sponges side-by-side to cover the folded towel; and then another layer of foot square of ¼” plywood. Again the bowling ball is dropped as before.

Got your answers yet?

Situation one is like a speaker without spikes and without extra vibration absorption.

Situation two is like a speaker with solid spikes. The cabinet vibrates less because some energy is transferred to the sub-flooring. If your sub-flooring is thick cement, you’ve probably done a good thing, little sound emission from the floor. If your sub-flooring is plywood or hardwood strips on wooden joists, your subwoofer has turned your sub-flooring into something like the surface of an acoustic guitar - if your spikes are solid end-to-end, the spikes are like a guitar’s bridge and the floor is a sounding board, plenty of sound emission from the floor.

Situation three is like a loudspeaker sitting on a multi-layer vibration absorber-dampener. The cabinet vibrates less because some if the kinetic energy goes into the layers. The floor vibrates less because the layers keep the kinetic energy isolated from the floor.

What’s your preference?